8 - Do an Shinichi (2!6!2012)_Finish

7/31/2019 8 - Do an Shinichi (2!6!2012)_Finish

1/68

n tt nghip Trng i hc M- a cht

M U

Hin nay, ngun du th cung cp cho cc nh my lc du phn ln l nhng

sn phm du nng, cha nhiu lu hunh, nit v cc d nguyn t khc. Do u

cn phi s dng n qu trnh HP thc hin qu trnh lc du. Nh vy, lngxc tc s dng cho qu trnh ny ngy cng gia tng v ng ngha vi vic lng

xc tc thi ca qu trnh HP ngy cng nhiu. Theo c tnh nm 2007, lng cht

xc tc thi b t qu trnh HP thi ra trn ton Th gii l khong 150000 n

170000 tn [Ref.]. V vi d kin lng xc tc tiu th hng nm s tng ln 5%

khi lng xc tc thi pht sinh t qu trnh HP ny s vt qu 200000 tn mi

nm trong vi nm ti.

nc ta, nh my lc du u tin i vo hot ng tnh cho ti nay c 5 nm. Nh vy, nh my tri qua mt chu k hot ng ca cc loi xc tc

trong c xc tc ca qu trnh HT. Va qua nh my lc du Dung Qut tin

hnh bo dng v i vo giai on sn xut mi, mt lng ln xc tc qua s

dng c thi ra, iu ny c nh hng nhiu ti mi trng. Do vy, vn t ra

cho cc nh khoa hc v cc nh sn xut l phi ti ch lng xc tc ny s dng

cho nhiu mc ch khc nhau nhm gii quyt vn mi trng v mang li hiu

qu kinh t.

c nhiu cng ngh s dng cho qu trnh ti ch ngun kim loi c gi tr

t xc tc thi ca qu trnh HP nh: cng ngh tch, chit cc kim loi qu,ng

dng cho cc mc ch khc nhau nh s dng cho cc nh my luyn kim, hoc s

dng ch to cht xc tc cho cc qu trnh x l kh, v cc qu trnh cng ngh

khc[51].

Mt trong nhng cng ngh quan trng trong nh cc nh my lc du l qu

trnh HP, nht l i vi nc ta ang hi nhp vi cc quc gia trn th gii th tiu

chun v hm lng lu hunh trong nhin liu cng phi ph hp vi xu hng ca th

gii. Hn na, trong tng lai cc nh my lc du ca Vit Nam s s dng ngun

nguyn liu du th cha 50% du chua ca Trung ng c hm lng lu hunh cao

nn qu trnh hydro ha kh lu hunh l khng th thiu trong cc nh my lc du

hin nay.

Chnh v vy, cn phi tin hnh nghin cu tng bc nm bt v ch ng

cng ngh cho qu trnh hydro ha kh lu hunh trong nhin liu. V sm a ra

phng n x l, ng thi tn dng ngun xc tc thi b nhm ti ch thnh xc tc

SV. Nguyn B Duy 1 GVHD: TS.Phm Xun Ni


2/68


mi cho qu trnh ny va mang li hiu qu kinh t va m bo cc vn mi trng

ca Vit Nam trong giai on hin nay.

Chnh v vy, mc tiu ca n tin hnh: "Nghin cu, tng hp xc tc

CoMo/-Al2O3 t ngun xc tc thi b s dng cho qu trnh hydro ha kh luhunh trong nhin liu.

n s thc hin cc ni dung sau:

Tch Mo, Co ra khi xc tc s dng v xc nh hiu sut thu hi

kim loi .

Ti ch cht mang -Al2O3 v c trng cc tnh cht ho l ca cht

mang.

iu ch xc tc CoMo/-Al2O3 v c trng cc tnh cht ho l caxc tc.

Th nghim hot tnh xc tc trong phn ng hydro ho kh lu hunh

nhin liu diesel.



3/68


CHNG 1 TNG QUAN L THUYT

1.1 Tng quan v xc tc thi ca nh my lc du

Lng xc tc c s dng cho qu trnh ny ngy cng gia tng do cc

ngun du th cung cp cho cc nh my lc du hin nay c xu hng l nhng sn

phm du nng, cha nhiu S, N, cc d nguyn t do u cn phi dng n qu

trnh HP thc hin qu trnh lc du. Nm 2004, lng xc tc thi s dng cho

cc quy trnh HP l 120000 tn v d kin tng 4.4% mi nm [50]. Sau mt thi

gian s dng cc cht xc tc b mt hot tnh nn cn c ti sinh li tip tc s

dng hoc khi khng th ti sinh th b thi b nh nhng cht thi rn. Theo c

tnh, nm 2007 lng cht xc tc thi ca qu trnh HP thi ra mi nm trn ton th

gii l khong 150000 n 170000 tn. V vi d kin lng tiu th xc tc hngnm tng 5% th lng xc tc thi ca pht sinh ca cc qu trnh HP s vt qu

200000 tn mi nm trong vi nm na [49]

Vic x l cht xc tc thi i hi phi tun th nhng yu cu nghim ngt

v mi trng do cht xc tc thi ca qu trnh HP c c quan bo v mi

trng EPA ca Hoa K xp vo nhm cht thi nguy hi. Cc kim loi nh Co, Ni,

V trong xc tc thi c th c ngm vo nc sau khi x l v gy nhim mi

trng, cc kim loi khc nh: As, Cr, Cd, Hg, Se, Pb cng c th c mt. Cht xc

tc thi cng c lit k theo cc iu khon kim sot ca Cng c Basel v t

chc hp tc kinh t v pht trin (OECD) quy nh. Do cn phi c bin php ti

to li cc cht xc tc ny nh sn xut cc hp nht nhm, ct liu tng hp,

anorthite thy tinh, gm, xi mng vt liu chu la t cc cht xc tc thi HP cng

c tp trung vo pht trin gn y.

Tnh ti nay, cng c nhiu nghin cu v thu hi kim loi t cht xc tc thi

HP c pht trin nhm mc ch thng mi qu trnh thu hi kim loi t cht xc

tc thi. T vic thu hi kim loi trong cht xc tc thi chng ta c th ch to ranhng cht xc tc mi cho qu trnh loi b S trong nhin liu. Trong du m lun

tn ti cc hp cht cha lu hunh. Cc cht ny l nhng cht khng mong mun

trong qu trnh ch bin cng nh s dng du m v cc sn phm ca n. Lu

hunh trong du th, khi ch bin s gy n mn thit b, gy ng c xc tc, gy

nhim mi trng. Lu hunh trong nhin liu, khi chy s to ra kh SOx, gy

nhim mi trng (ma axit), n mn ng c. V vy cn phi loi lu hunh ra

khi du m v cc sn phm du m.

Yu t quan trng nht nh hng n qu trnh tch lu hunh l phi loic gn nh hon ton lu hunh trong khi vn gi c cc tnh cht tt ca



4/68


nguyn liu. Mt tnh cht khc ca lu hunh l gy ng c xc tc rt mnh vi

hu ht cc loi xc tc thng thng. V vy xc tc cho qu trnh HDS c quan

tm c bit v lin tc c ci tin. Hin nay xc tc ang c ng dng rng ri

v cho hiu qu cao l xc tc c s Co, Mo mang trn cht mang nhm oxit hot

tnh.

1.2 Xc tc thi ca qu trnh HDS

1.2.1 Cc c tnh nguy him ca xc tc thi

Theo t chc bo v mi trng - EPA, cht thi nguy him c xc nh

chc chn hoc c kh nng gy nguy him ti sc khe con ngi v mi trng

nu khng c qun l. C hai tiu chun thng c s dng nhn bit cht

thi nguy him, nh: Cc c tnh c th ch ra bng cc tnh cht l - ha hc m rc thi gy ra

nguy hi.

Cc tnh cht xc nh c tnh nguy hi phi c o lng v nh lng

bng cc bng bo co kim tra v phi c nhn thy l pht sinh cc cht

thi nguy hi.

Cc thnh phn c kh nng gy hi lin quan ti xc tc thi, trong danh

sch hng dn dng, c ch ra bng 1.1.

Bng1.1 Cc thnh phn rn c kh nng gy hi [1]

Cc hp phn c Be, V, He, Cr, Co, Ni, Cu, Zn, As, Se, Te, Ag, Cd, Sn, Sb, Ba, Hg,

Pb v Ta.Cc axit v cCc sulphit v cCc hp phn Flo v c, loi tr CaF2Cc Cyanit v cCc Phenol

Cc EteCc hp phn thm; Polycyclic v HeterocylicCc thnh phn Nito hu c, c bit l cc Amin thm v AliphaticCc hp phn sulphua hu cCc thnh phn c th gy nCc hp phn Halogen hu c

T chc EPA thm xc tc thi HT v xc tc thi hydrorefining vo loi

cht thi nguy hi vo thng 8 nm 1998[2] bi kh nng t pht nhit v thnh phn



5/68


ha hc c hi. Xc tc hydrocracking cng c thm vo danh sch nm

1999[3].

Bng 1.2 Cc c tnh nguy hi [1]

Gy nBt chyC th gy chyn mnC c tnhGii phng cc kh c khi tip xc vi khng kh v ncC kh nng, bng bt c l do no tr thnh cc nguyn liu mm d phn ng

Hin nhin l cc c tnh nguy hi trong bng 1.2 [1], cc cht thi nguy hi

c lu tm v kh nng pht sinh ca cc cht c vo khng kh v/hoc nc.

Cc c tnh, nh gy n, chy v bt chy khi c tc nhn u c phng hnch thp nht tip xc vi khng kh trong trng hp xc tc thi khng c loi

coke v sy kh. Cht c c th pht sinh vo kh quyn hoc vo nc ngm gy

hi cho sc khe cho con ngi khi b nh hng ca thi tit. Cc quy tc c bit

v cc vn bn ban hnh v nh hng ca cc hot ng lin quan ti xc tc thi

nh: thi, cha, vn chuyn, vi lp cng phi c ch .

Cc phng php phn tch c s dng xc nh tnh cht nguy hi

c nh gi bi McKenna v Pickering [4]. V d, n mn c th xc nh n

gin bng phng php o pH cht rn. Kim tra phn ng cyanide, cc mu c

gi trong h thng kn v c acid ha ti pH bng 2, cc kh pht sinh c ra v

phn tch. Vi phn ng vi sulphide, cc mu c acid ha trong h thng kn, cc

kh pht sinh cng c ra v phn tch. Mc ch ca phn ng kim tra cyanide

v sulphide l xc nh kh nng pht sinh kh HCN v H2S.

Kh nng pht nhit ca xc tc thi c th c xc nh s dng phng

php Pensky-Marten, phng php ny c th c s dng rng ri trong cng

nghip lc du xc nh kh nng bt chy ca nhin liu. Theo phng php ny,

mt mu c gia nhit vi p sut kh quyn trc tip xc nh nhit bt chy.

Nhit thp nht, khi mu bay hi bt chy, n c gi l im chp chy. Mt

im chp chy xy ra nhit thp c th do l xc tc cha c loi du v sy

kh. Nh vy, kh nng pht nhit ca xc tc thi s cao.

1.2.2 Pht n trong khng kh

Mt s phn ng pht sinh kh c v mt s pht sinh nhit c th gy n

trong khng kh hoc khi c mt ca nc. Cc thnh phn hu c (coke) v v c



6/68


cha trong xc tc thi, u c kh nng pht n mc d phng thc kh khc nhau.

Phi ch rng cc phn ng ny xy ra tc rt chm, nh th nh hng ca

chng c th ch nhn ra sau mt thi gian di.

1.2.3 Phn ng ca khng kh vi cokeKhi n trong khng kh, kh nng bt chy v pht nhit ca xc tc thi l

nhn t cn ch u tin. Nh nhn thy trn, xc tc thi c th pht nhit nu

p sut bay hi cc kh d bt chy trn b mt ca n. Cc kh d chy c th

l H2 v cc hydrocarbon b by trn b mt coke. Kh nng bt chy c th hn ch

ti mc thp nht khi thc hin tin x l xc tc thi, nhloi du v sy kh

bng trong H2 trong kh tr. Qu trnh c th thc hin song song nh my lc du

vi mc ch hn ch cc tc hi ca xc tc thi vi t nhin.

1.2.4 Phn ng ca khng kh v xc tc

Khi tip xc vi khng kh iu kin kh, cc nguyn liu ca xc tc thi

xy ra qu trnh oxi ha chm thm ch vi nhit mi trng. Tuy nhin, khi xem

xt vi trch nhim php l v thi hn, th s xy ha chm cng cn phi c ch

nu n pht sinh nhng thnh phn c hi. Nh vy, qu trnh xy ha cc hp

cht sulphua v c trong rc thi rn (coke) phi c ch khi tip xc vi

khng kh ngay c sau hn 50 nm.

Khi tip xc vi khng kh, cc dng sulphide kim loi b chuyn ha thnh

dng oxit. Qu trnh ny rt chm v c th km theo s thay th cc nguyn t S

bng cc nguyn t O hnh thnh oxysulphide trung gian trc khi qu trnh oxy

ha hon ton xy ra. V d, vi MoS2 m t theo cc phn ng sau:

MoS2 + O2 MoSO + SO

MoSO + O2 MoO2 + SO

2SO + O2 SO2

MoO2 + 0.5O2 MoO3

Tng th ca qu trnh chuyn ha l MoS2 thnh MoO3:

MoS2 + 3.5O2 MoO3 + 2SO2

Tuy nhin, s oxy ha hon ton ca MoS2 khi vi lp trong t din ra rt

chm. C th xy ra phn ng chuyn ha MoS2 thnh Mo(SO4)2:

MoS2 + 2O2 Mo(SO4)2



7/68


Mc d s khuch tn O2 l chm bi cc lp coke bm trn b mt ngn cn

phn ng trn xy ra. Nhng cc sulphide kim loi, mt phn ca cc xc tc thi

HP, c th vn xy ra s chuyn ha tng t thnh cch oxit kim loi tng ng qua

cc hp cht oxosulphide kim loi trung gian. V d vi qu trnh oxy ha Ni 3S2 c

th xy ra nh sau:

Ni3S2 + O2 Ni3SO + SO

Ni3SO + 1.5O2 3NiO + SO

2SO + O2 2SO2

Ni3S2 + 3.5O2 3NiO + 2SO2

Tng th chuyn ha ny l Ni3S2 thnh NiSO4 nh sau:

Ni3S2 + 4.5O2 2NiSO4 + NiO

Bi trc khi t c gii hn bn, cc sulphide hoc oxysulphide kim loi

chuyn hon ton thnh SO sau vi O2 thnh cc dng bn hn SO2 v nu O2

s chuyn thnh SO3.

Vi s c mt ca nc, cc phn ng khi xc tc tip xc vi khng kh c

th to ra cc sn phm c d on trc nh:

SO2 + H2O H2SO3

H2SO3 + 0.5O2 H2SO4

S hnh thnh H2SO4 c th l mt trong cc l do phn loi xc tc HP l loi

cht thi n mn. Hn na, s c mt ca H2SO4 c th nh hng nhiu ti xc tc

thi bi kh nng pht sinh H2S khi cc sulphide kim loi khng c chuyn

ha:

MoS2 + H2SO4 Mo(SO4)2 + H2S

Vi phn ng tng t, H2S s pht sinh t vic chuyn ha cc sulphide kim

loi khc c trong thnh phn xc tc thi. Kh nng pht sinh H2S l mt c tnh

c ca xc tc thi. Vi vic oxy ha trc cc nguyn liu rn, s dng H2O2 trc

khi vi lp, c th gim ng k hm lng sulphidic, sulphur [5]. Nh th, s pht

sinh H2S vo mi trng c th hn ch thp nht. S hnh thnh H2SO4 cng tng

kh nng thm v n mn. Vi s c mt ca H 2SO4 pht sinh cc cht c nh

HCN, cng ng phi quan ngi.

Nghin cu ca Afonso[6] l s b sung hu ch cho cc l lun trn. Tc giny vi xc tc NiMo/Al2O3 trong cc hp kim loi xung lng t ( su 30



8/68


50 cm) cho tip xc vi mi trng trong khong 40-70 ngy. Sau xc nh s

thay i cc thnh phn cu nguyn liu v cc hp cht hu c trong xc tc thi.

Sau 14 thng, Al v cc phosphate khng b ha tan trong khi hu ht cc sulphua b

chuyn ha thnh sulphate. Kh nng chuyn Ni v Mo thnh pha lng tng ng k.

St xut hin trong pha lng lm tng n mn cc kim loi thnh phn. Cng vi ,

kh nng ha tan ca coke trong dicloromethane b gim nhiu, nhng kh nng tan

ca coke trong methanol li tng. Kh nng tan trong methanol tng c trng cho s

hnh thnh cc nhm cha oxy nh cc axit, cc ete, cc este v cc phenol. Sau 6

thng, to thnh cc l trn b mt hp kim loi, c th on c hnh thnh

cc hp cht n mn nh.., H2SO4. V cng xc nh c trong nc ngm c

cha Ni, Fe, Mo dng sulphate.

Cc pha hot tnh cha Co(Ni)-Mo(W) S [7] c th vn tn ti trong xc tcthi HP. Cc kim loi Ni v Co nh trn cc tinh th MoS 2 hoc WS2 d dng thc

hin phn ng oxy ha:

Ni(Co) Mo(W)-SX + O2 NiO(CoO) + Mo(W)-SX

S oxy ha Mo(W)-SX s dn ti cc phn ng nh ni trn.

S c mt ca floride v phosphate cng nhn c s ch . Bi v chng s

nh hng ti cht mang Al2O3. Tuy khng c bt k d liu thc nghim no c

cung cp nhng s pht sinh HF c th c d on trc nu nng H 2SO4 ln v khi xc xc tc thi tip xc vi khng kh v nc. Tng t, Al 2O3 vi

phosphorus c th chuyn thnh Al2(SO4)3 dng khng bn.

C kh nhiu hp phn c cha As (Arsene) trong du m [8]. Trong qu

trnh HP, mt phn As s bm ln b mt xc tc, dng sulphidic v c th pht

sinh kh AsH3. Tng t nh qu trnh oxy ha vi cc sulfide kim loi khc, c th

to ra arsene sulphide ri arsene oxit ri cc arsenic s ngm vo nc ngm lm

tng c t trong t nhin.

1.3 Cc nghin cu trong phng th nghim v ti sinh kim loi t cc xc tc

HP thi

Cc nh my lc du phi ch ti cc xc tc HP thi c bit t khi chng

c coi l rc thi nguy him c hi. Trng tm ca cc nghin cu l quy trnh ci

tin ti ch cc kim loi v cc phng php loi b gii quyt c cc vn



9/68


nhim mi trng ca cc xc thi. Cc nghin cu c a ra vi mc ch

tng hiu qu thu hi cc kim loi khi s dng cc phng php c cp hoc

pht trin phng php khc. Cc nghin cu v phng php chit s dng cc tc

nhn v c nh cc dung dch axit v bazo mnh, cc hp phn c cha amoni v cc

dung dch acid hu c. Cc xc tc thi c nung vi mui natri hoc kali c tc

dng ci thin tan ca mt s kim loi trong nc t chng c th c thu

hi, dng nguyn cht, cng nh kt ta chn lc hoc chit s dng cc tc nhn

khc. Cc phng php ha tan chit sinh hc v in ha hc ca cc kim loi cng

c c cp. Cc qu trnh thng mi, bao gm chit loi cc kim loi hoc

nung ha tan cc kim loi tan c trong nc. m bo mi trng, la chn

cui cng l vi lp nhng yu cu cc xc tc thi phi tri qua quy trnh tin x l.

Nhiu phng nghin cu cng nghip v cc vin nghin cu c gng ara cng ngh gim lng xc tc thi pht sinh cng nh cc phng php gim

gi thnh cho ti ch nguyn liu xc tc thi nhiu nht c th. Cc nghin cu

ch ra mt s qu trnh c th s dng t c tiu chun v mi trng ca xc

tc thi. Cc qu trnh c th phn loi vo 4 nhm sau:

Hn th thp nht lng xc tc thi pht sinh

ng dng sn xut cc xc tc mi v cc nguyn liu hu dng

Ti ch v thu hi cc kim loi

X l cc xc tc thi vi lp an ton

Hu ht cc nghin cu v ti sinh cc kim loi t cc xc tc HP u tri

qua quy trnh ngm chit vi cc dung mi tc nhn v c v hu c. Ngm chit vi

axit, vt liu micro,..., ngm chit sinh hc cng c trnh by v dnh c nhiu

s quan tm. Kh nng ha tan cc kim loi trong nc c tng cng khi nung

cc xc tc thi vi mt lng kim loi kim nh natri v kali. Kh nng ha tan cc

kim loi c th d dng hn khi thc hin theo cng ngh clo ha. Cc th nghim

pht trin thnh cc phng php c th cnh tranh vi cc phng php thng

thng ti sinh kim loi.



10/68


Hnh 1.1 Mt s dung mi chit trong thng mi

Vi dung mi, cc kim loi c th b tch v dng tinh khit s dng cc

phng php thng dng trn c s lng chn lc. Trong nhiu thp k, cc th

nghim tch cc kim loi c thc hin bi nhiu dung mi khc nhau bao gm c

cc tc nhn chit. Mt s dung mi chit s dng trong thng mi c ch ra

hnh 1.1.

1.3.1 Chit vi dung dch amoni v mui amoni

Dung dch amoni v cc mui amoni c s dng trong nhiu nghin cu

chit cc kim loi nh Mo, V, Co v Ni t cc xc tc thi. Cng ngh pht trin bi

Gutnikov (1971), s dng dung dch amoni cacbonate ngm chit cc kim loi t

cc xc tc thi v ti sinh c hn 90% Mo v V, v 60 -70% Ni. Thi gian ngm

chit v nhit ngm chit s dng trong nghin cu ny l: 1h v 150oC. Mt cng

ngh tng t c a ra bi Millsap v Reisler [9] chit cc kim loi qu t xc

tc Ni-Mo/Al2O3. Xc tc u tin c nung v sau ngm chit vi dung dch

amoni hydroxit v amoni cacbonate chit Mo v Ni cn Al 2O3 dng rn. Ni c

kt ta dng mui cacbonate sau khi phn tch lng d amoni t cc dung dch

ngm chit. Mo c ti sinh bi dung mi chit tch v kt ta dng mui Mo.

Marcantonio [10] s dng mt dung dch ca amoni, mui amoni v hydro

peroxide chit cc kim loi (V, Mo, Ni v Co) t cc xc tc thi. Cc mui amonic s dng nghin cu l (NH4)2CO3 v (NH4)2SO4. Vi pH ban u, nng



11/68


amoni, mui amoni v H2O2 trong hn hp c nh hng ln trong khong chit cc

kim loi. Cc sn phm chit V v Co c thm H2O2 vo tc nhn amoni + mui

amoni, trong khi cc cht chit Mo v Ni khng nh hng bi H 2O2. Kt qu chit

c 93% Mo, 88%V, 80% Ni v 78% Co khi ngm chit vi cc tc nhn c pH ban

u l 10.4, nng amonia, mui amoni v H2O2 tng ng l 2; 0.5 v 0.14.

Mt nghin cu khc gn y ca Marcantonio [11] s dng k thut chit p

sut amoni c s xut hin oxy to thnh amoni Mo, amoni Meta V (AMV) v

amoni Ni sunphite t cc xc tc HP c cha Mo,V v Ni. Cc phn ng xy ra trong

qu trnh nh sau:

MoS2 + 4.5O2 + 6NH3 + 3H2O (NH4)2MoO4 + 2(NH4)2SO4

V2S3 + 7O2 + 6NH3 + 3H2O 2NH4VO3 + 3(NH4)2SO4NiS + 2O2 + 6NH3 Ni(NH3)6SO4

Dung dch c kt ta trng dng amoni meta V c lc v chuyn ha thnh

V2O5 khi nung. Dung dch cha Mo v Ni dng thm tc nhn chit to ra V

pentoxit, Mo amoni v Ni sunphate l sn phm cui trong qu trnh ny.

1.3.2 Chit vi axit

Cc quy trnh chit kim loi c mt trong xc tc thi bng axit c

nghin cu kh nhiu v c tng kt bng 1.3.

Bng 1.3 Hiu sut chit kim loi t mt s xc tc thi bng phng php

chit axit

Kim loi c

trong xc tc

thi

Tc nhn chit Kim loi thu hi (% Klg) Tham khoMo V Ni Co Al

Mo, V, Ni, Co,

Al2O3H2SO4

99,

7

92,

5- - - [12]

Mo, Ni, Al2O3 H2SO4 93 - 98 - 96 [13]Co, Mo Dung dch SO2 100 - - 100 [14]Co, Mo H2SO4 + HNO3 (3:1) 96 - - 96 - [14]

Co, MoH2SO4 + Al2(SO4)3

hoc (NH4)2SO492 - - 97 - [15]

Mo, Co, Ni H2SO4 + H2S - - - - - [16]Mo, V, Co, Ni H2SO4 >90 - - >90 - [17]Mo, V, Ni, Al Axit Oxalic + H2O2 90 94 65 - 33 [18]

Mo, V, Ni Axit Tartaric 93 94 83 - - [19]Mo, V, Ni Axit Citric 94 94 85 [19]



12/68


Mo, V, Co, Ni,

AlH2SO4 - - - - - [20]

iu ny chng t rng cc axit v c nh: HCl, H2SO4 v HNO3 c s

dng lm dung mi chit rt nhiu. Tuy vy, vi cc tc nhn hu c, dung dch axit

v c, dung mi acid hu c cn phi cn nhc chc chn cc vn mi trng v

yu cu quy trnh thc hin an ton hn.

1.3.2.1 Cc axit v c

Trong cng ngh thng mi c pht trin bi Hyatt [16], xc tc thi

(CoMo/Al2O3) c x l vi H2SO4 vi s c mt ca H2S di p sut (7.5-15 atm)

trong autoclave 100 200oC. S c mt ca H2S khi chit vi H2SO4, lm xut hin

kt ta ca Mo v Co dng sulphide trong khi Al2O3 c chuyn sang dng ha

tan c l Al2(SO4)3. Cc sulphide kim loi c tch khi dung dch Al 2(SO4)3 v

c oxy ha di p sut trong autoclave chuyn ha MoS2 thnh acid molybdic

rn v CoS thnh CoSO4. Axit molybdic c tch bng phng php lc t dung

dch CoSO4. Cobalt c thu hi bng phng php trao i Ion. S khi ca qu

trnh c ch ra hnh 1.2.



13/68


Lc kt ta trong Autoclave150oC ; 150 psig H2S

Tch lng/rn

Dung dch cha Mo-Ni,Co sulfide

Oxy ha trong Autoclave

Lc/ra

Thc c Cation trong keo ban u

ThCation trong keo t ch

H2O

H2O

O2

H2O

H2S

H2SO4 98%

Dung dchAl2(SO4)3

MoO3.H2O

Keo tun hon

Cht lng tun hont i Autoclave

H2SO4

Dung dch Co-Ni

Hnh 1.2 Bc u tin ca quy trnh tch kim loi trong xc tc HDS thi bng

H2SO4 vi s c mt ca H2S [16]

Toyabe [20] ci tin qu trnh chit vi axit (H2SO4) chit hon ton v

thu hi tt c cc thnh phn (bao gm c Al) ca cc xc tc thi HP cha Mo, C,

Ni, Co trn cht mang Al2O3. Cng ngh bao gm cc bc sau:

Nung xc tc thi khong nhit 400-1000oC thu c sn phm nung

Ha tan sn phm nung vi axit sulphuric vi s c mt ca kim loi (Al)

nh l mt xc tc ha tan

Tch mt phn ln Al t dung dch ha tan v thu hi Al dng amoni alumi

sulphate t dung dch, sau dung dch tip tc x l loi b st.

Chit molybdenum dng mui molybdate bng dung mi chit t dung dch

sau khi tch v thu hi Al.



14/68


Chit vanadium dng vanadate bng dung mi chit t dung dch cha cn

sau khi chit molybdenum.

Thu hi nikel v cobalt dng hydroxide t cn chit sau khi loi b

vanadium.Cng ngh c pht trin bi cng ty ha cht Hall (Ohio), axit clohydric

c s dng chit cc kim loi t xc tc thi HDS [21]. Xc tc thi c ha

tan hon ton trong HCl sau Mo c kt ta trc tin dng sulphide bng cch

cho thm H2S. Tip , V c tch ra bng dung mi chit, khi cho thm nc soda,

v kt ta thu c dng vanadium pentoxide. Nickel c tch bi dung mi

chit, v sau thu hi dng sulphate khi cho thm axit sulphuric. Cobalt c tn

dng ty theo mc ch ngi s dng.

Rabah [22] s dng hn hp dung dch axit sulphuric v axit nitric (3:1)

chit Mo v Co t xc tc thi HDS. Sau khi chit, cc kim loi c tch ra dng

hydroxide, sau c nung trong khng kh thu c cc oxit tng ng. Qu

trnh kh cc oxit Mo v Co trong hydro nhit tng ng l 1100 oC v 900oC,

thu c cc kim loi dng bt vi tinh khit cao. Hiu sut thu hi ti a c th

t c l 96%.

S dng dung dch nc SO2 chit cc kim loi t xc tc thi HDS

CoMo/Al2O3 c nghin cu bi Raisoni and Dixit [14]. C Co v Mo u b hatan nhanh t xc tc thi nung bi dung dch nc SO 2 c pH = 1 v chit c

100% c hai kim loi thi c trong 8-10 pht trong nhit mi trng. Xc tc

thi c s dng trong nghin cu ny cha Co3O4 6,12%; MoO3 10,83%; Al2O3

65,15%; SiO2 17,7%, S 0,10% v C 0,35%. Cc phn ng ca Co v Mo vi dung

dch nc SO2 xy ra trong qu trnh ha tan:

2Co + 3SO2 + 4H2O CoSO4 + CoS2O6 + 8H+

4Mo + 12SO2 + 16H2O 2Mo(SO4)2 + 2Mo(S2O6)2 + 16H+

1.3.2.2 Cc axit hu c

Chit cc kim loi c trong xc tc thi vi cc acid hu c c nghin cu

kh nhiu. Beuther [23] so snh hiu sut chit ca mt s axit hu c nh oxalic,

lactic, citric, glycolic, phthalic, malonic, succinic, salicyclic v tartaric chit cc

kim loi (V, Mo, Ni, Co) t mt s xc tc thi. Nghin cu s dng dung dch axit

1% , nhit mi trng v p sut kh. Chit bng axit oxalic thu c hiu sut

cao nht vi bn kim loi l 47% V; 58% Mo; 60% Co v 56%.



15/68


Hnh 1.3 nh hng ca H2C2O4 ti hiu sut chit kim loi 50oC vi tc

nhn H2O2 3.0M khi chit trong 4h [18]

Mt nghin cu c cng b bi Mulak [18] tp trung vo ti u ha cc

thng s ca cng ngh chit Mo, Ni, V v Al t xc tc HDS thi s dng dung dch

axit oxalic cng vi H2O2. nh hng ca nng axit oxalic, nng H 2O2 v tc

khuy ca qu trnh chit kim loi cng c nghin cu. Cc kt qu ch ra rng

khi thm H2O2 vo axit oxalic ti khi H2O2 t ti 3M th kh nng chit tng ngk, v sau n khng i. Thay i nng ca dung dch axit oxalic trong khong

0,25 - 0,7M lm tng dn kh nng chit ca tt c cc kim loi ti 0,5M v sau

gim nh khi tng ti 0,7M (hnh 1.3). Hiu sut chit cc kim loi cao nht t xc

tc thi ( 50oC, 4 gi, tc nhn H2C2O4 0,5M v H2O2 3M) c xc nh l 90%

Mo, 94% V, 65% Ni v 33% Al.

1.3.3 Chit bng kim

Chit xc tc thi vi dung dch (NaOH hoc Na2CO3) c cng b trong

mt s nghin cu. Rokukawa [24] a ra cng ngh dng dung dch kim ca

Na2CO3 cng vi H2O2 nh l mt tc nhn oxi ha s dng chit Mo v V chn

lc t xc tc thi cha nung. Hn 99% Mo v khong 85% V c thu hi trong

cng ngh trong khi lng Ni, Co v Al chit c l thp.



16/68


Gimkch c(100 micron)

Chit 20%PD,RT,1h

Hp ph CpH =0,75;3h40% PD

Nhhp ph30%PD , 3h

Cc nguyn liu

Nung 450 oC

Na2CO3(40g/L)H2O2(6% V)

C hot tnh

NH4OH15%V

HCl

Cn

N- c lc

C t i sinh

N-c lc

LL, pH =4

Hp ph C

AmoniMolybdate

Kt ta AmoniMolybdate

MoO 3Tinh khit (99,4%)

Xc t c thi

Hnh 1.4 S khi ca cng ngh chit Mo t xc tc thi bng Na2CO3 +

H2O2 [25]

Nghin cu ny c ci tin gn y bi Park [25, 26] cho qu trnh chit

chn lc cho tinh khit cao MoO3 t xc tc thi HDS s dng hn hp Na 2CO3

v H2O2. Kt qu thu c ch ra rng hiu sut thu hi Mo ph thuc nhiu vo

nng ca Na2CO3 v H2O2, axit (pH) ca dung dch chit. Qu trnh chit l ta

nhit v hiu sut chit ca Mo gim khi tng t l rn/ lng. Vi quy m chit ln,

di cc iu kin ti u (khi lng ring 20%, 85 g/l Na2CO3, 10% th tch H2O2

v thi gian phn ng 1gi), c th thu hi c 84% Mo. Dung dch chit thu c

cha (g/l): Mo 22; Ni 0,015 v Al 0,82; P 1,1; Si 0,094 v mt lng V 8mg/l, As v

Co < 1mg/l. Kt tinh dung dch lc bng cch hp th C pH khong 0,75 v nh

hp ph molybdate vi 15% NH4OH thu c molypdate vi tinh khit cao v

cui cng thu c MoO3 vi tinh khit 99,4% sau khi nung. Quy trnh chit c

trnh by hnh 1.4



17/68


1.3.4 Chit hai bc

Cng ngh c thc hin bi Jong [27] c hai bc. Bc u tin l chit xc

tc thi NiMo/Al2O3 vi dung dch NaOH chit Mo v mt t Al, trong khi phnln Al v Ni d trong cn. Mo c tch ra t dung dch chit NaOH bng phng

php kt ta vi CaCl2. Trong bc th hai, cn ca bc th nht c chit vi axit

sulphuric chit Ni. Nc lc ca bc ny c x l vi NH4OH v (NH4)2SO4

kt ta Al v cc kim loi tp cht khc. pH 10, Ni c thu hi bi dung mi

chit. Bc chit NaOH thu c 81 91% Mo. Bc chit H2SO4 chit c 92-98%

Ni. Ton b quy trnh thu c hn 84% Mo v 99%Ni.

Sun [28] s dng dung dch ammonia c c trong bc u tin v 10% H2SO4trong bc th hai chit Mo v Co t xc tc thi CoMo/Al2O3. Hiu sut chit l

83% Mo, 77% Co v 4% Al. Trong mt nghin cu khc, tc gi ny c th thu hi

83% Mo v 44%Ni t xc tc thi NiMo/Al2O3 s dng amonia trong bc u tin v

H2SO4 trong bc th hai.

1.3.5 Chit sinh hc

Chit sinh hc c cp ti trong nhiu bo co thu hi kim loi t nhiu

cht thi rn. N da trn kh nng ca mt s vi khun chuyn i cc hp cht rn

vo dung dch chit. Trong trng hp ny, cc vi khun c th to ra cc axit hu c

v v c cha xc nh trong qu trnh ha tan kim loi. Chit sinh hc c s dng

trong cng nghip thu hi kh nhiu kim loi t cc ngun nguyn liu c hm

lng thp. Thm vo , cng b bi Santhiya [29] cho thy mt lot cc nguyn

liu thi nh, tro bay, bn thi, pin thi v cc nguyn liu in, ngay c xc tc FCC

v HP c coi nh l cc cht thi rn c tim nng c th thc hin chit sinh hc.

Hu ht cc vi khun thng thng c kh nng ha tan cc kim loi bao gm cc

loi nh Thiobacillus Ferrooxidans v T.thiooxidans, v cc loi nm Aspergillus vPenicilium [30].

C s khc nhau cht t trong hiu sut chit sinh hc gia bc 1 v bc 2

c cp trong trng hp xc tc l NiMo/Al2O3. Thc nghim, cc phn t nh

hn (v d, 100-150 m v < 37 m), ha tan Ni v Mo th cao hn Al. Khi

ng knh trung bnh khong 2,97 m th nm chuyn khi thp hn cc axit hu

c. Khi chit sinh hc khong 70 ngy vi kch thc Ni



18/68


1.3.6 Chit vi cc hp cht kim

Kh nng tan ca mt s kim loi (nh Mo,W v V) trong nc c th ctng ln bi vic nung xc tc thi vi cc hp phn cha cc kim loi kim. Sau khi

nung ton b Ni v Co thu c dng cn rn khng tan sau khi chit bng nc.

Mt s phng php c s dng tch cc kim loi khi dung dch nc. Cc

hp cht cha Na v K u c s dng lm tc nhn nung.

1.3.6.1 Nung vi mui Na

Nung xc tc thi vi mui Na (Na2CO3, NaCl v NaOH) bng phng php

chit v tch cc kim loi c cp trong nhiu nghin cu.

Wang [31] nghin cu thu hi Mo, Co v Al 2O3 t xc tc thi CoMo/Al2O3

s dng nung kim sau dng Ammonia v axit chit. Xc tc thi lc u c

loi coke v sau nung vi soda (Na2CO3). Sau khi nung, hn hp chit bng dung

dch ammonia thu c dung dch cha thnh phn chnh l Mo v cht rn thu c

ch yu l alumina v Co. Sau dung dch c x l vi axit nitric v ammonia

thu c ammonium molybdate c tinh khit cao. Cn c ha tan bi axit

sulphuric, v aluminum sulphate trong dung dch c kt tinh vi ammoniumsulphate hnh thnh ammonium alum. Co c chuyn thnh ion phc bi

ammonia bo ha v sau c thu hi dng bt Co c tinh khit cao bng

cch kh vi bt Zn. H s thu hi Mo, alumina v Co tng ng 90%, 85% v 90%.

Di cc iu kin thc nghim chn la (nung xc tc thi vi 12% soda

600oC trong 30 pht bng phng php chit vi nc) 92% Mo c chit dng

natri molybdate. Dung dch natri moblydate c x l vi HCl iu khin pH ti

2 v sau kt tinh bng phng php hp ph trn than hot tnh vi ammonia v

dung dch sy nhit 90oC thu c MoO3 (99,9%) c tinh khit cao. S

tng th qu trnh c ch ra hnh 1.5.



19/68


Xc t c thi

Na2CO3 +Khng kh, 600oC

Chit 90oC

Lc

N c lc Na2MoO4

X l ha hc

iu chnh pH =2

Amoni polymolybdate

Nung 450oC

Cn

Hp ph

iu chnh pH =2

Hp ph C

Nh hp ph, NH4OH

Nung 450oC

N c thi

MoO3

HCl

Amoni

MoO3

HCl

Gia nhitAmoni polymolybdate

Hnh 1.5 S tch MoO3 c tinh khit cao t xc tc thi Hydro- Refining

[32]

Trong mt nghin cu gn y [33], xc tc thi nung vi NaCl xc nhcc yu t nh hng thu hi Mo t xc tc HDS cha 21,8% MoO3; 4,97% NiO;

1,54% Co3O4; 60,4% Al2O3 v 5,06% SiO2. S khi ca qu trnh c ch ra

trong hnh 1.6. Di cc iu kin thc nghim ti u (nhit nung 900 oC, thm

20% khi lng NaCl vo nguyn liu v thi gian khong 60 pht). Hiu sut chit

t c l 90% Mo.



20/68


Xc t c thi

NaCl +Khng kh, 900oC

Chit bng n c

Lc

N c lc, Na2MoO4 Cn (Ni, Co v Al)

X l ha hc n c lc

iu chnh pH =2

Amoni polymolybdate

Nung 450oC

MoO3

HCl

Amoni

Hnh 1.6 S chit Mo t xc tc thi bng phng php nung mui

1.3.6.2 Nung vi mui Kali

Hn hp KHSO4 c s dng thu hi Mo, Ni, Co v Al ca cc xc tc

CoMo/Al2O3 v NiMo/Al2O3 [11]. Trong cng ngh ny, Mo, Ni, Co v Al chuyn

vo hn hp c th ha tan khi nung nhit cao (500 oC) vi KHSO4 theo cc

phn ng sau:

NiO + 2KHSO4 NiSO4 + K2SO4 + H2O

CoO + 2KHSO4 CoSO4 + K2SO4 + H2O

Al2O3 + 6KHSO4 Al2(SO4)3 + K2SO4 + H2OMoO3 + 2KHSO4 MoO2SO4 + K2SO4 + H2O

Cc kim loi c ha tan, sau c thu hi bng phng php kt ta

thng thng bng cc dung mi chit. Vi cng ngh ny, hn 96% Mo trong xc

tc thi c thu hi dng tinh th ammonium hepta molybdate dng

[(NH4)7Mo6O24.4H2O]. Hiu sut chit ca Ni, Co, Mo v Al trong qu trnh ny c

a ra trong bng 1.4. Cng ngh yu cu cht thi pht sinh trong qu trnh c c

tnh thp v c th coi l rc cng nghip hoc c ti sn xut thnh cc tc nhn.



21/68


22/68


V, Mo, Ni, Co,

AlNa2CO3 + H2O2 99 85 - - - [24]

Mo, Ni, Al, C, S Na2CO3 + H2O2 85 - 65 - - [25]

V, Ni, Mo, AlNaOH(10%); pH

8,891,8 88,5 20 - 35 [34]

V, Ni, Mo, AlNaOH(10%); pH

8,498,8 92,7 10 - 20 [37]

V, Ni, Mo NaOH (1atm, 2 bc) 97 92 - - - [38]

V, Ni, Mo, AlDung dch NH3

(17M)- 98,8 - - - [34]

Ni, Mo, AlNaOH (bc 1)

&H2SO4 (bc 2)84 - 98 - - [27]

Ni, Co, Mo, Al

NaOH (bc 1)

&H2SO4 (bc 2) 97 - 92 92

65-

75 [35]V, Mo, Ni, Co,

Al

Na2CO3(nung +

chit H2O)

90-

95

90-

95- - - [36]

V, Mo, Ni, Co,

Al

NaOH nung +

H2SO4 chit98,9 95,8 98,2 98,5 90,6 [39]

Mo, Ni, Al2O3NaCl nung + H2O

chit90 - - - - [33]

Mo, Ni, Co, AlKHSO4 nng chy +

H2O chit

96 - 90 90 85 [40]

V, Mo, Ni, CoDung dch (NH3 +

NH4CO3+H2O2)93 88 80 78 - [10]

Mo, V, Ni Axit Citric 94 94 85 - - [19]V, Mo, Ni, Al Axit Oxalic + H2O2 90 94 65 - 33 [18]

Thng thng, chit sinh hc c hiu sut chit cao hn t 3-20% chit ha

hc. Nhng tng quan th chit sinh hc khng th cnh tranh vi cc phng php

chit khc. Thi gian yu cu trong qu trnh chit sinh hc t c hiu sut

chit ln c th l tr ngi chnh ca phng php chit sinh hc.Vn mi trng c th c vai tr quyt nh tnh ton, so snh cc qu

trnh thng mi thu hi kim loi. V d, qu trnh nung v kh clo pht sinh cc

kh thi, yu cu cn c x l. Nu mt phng php khng c kh thi pht sinh,

th c th thay th cho bc chit u tin ca phng php nung v kh clo. y c

th l mt ci tin quan trng trong phng php chit so snh vi cc phng

php chit khc. Sau khi tch kim loi t dung dch chit s pht sinh cc cht lng

thi yu cu lm sch trc khi thi ra mi trng. Cng cn ch rng, khi loi

coke xc tc thi pht sinh cc kh nh SOx, NOx, NH3 phi loi b chng trong kh



23/68


thi. V vy phi cng on ny thng c ch trong tt c cc cng ngh thu hi

kim loi.

1.3.8 Phng php vi lp an ton

Khi quy trnh thu hi kim loi khng kh thi, vi lp l s la chn cui cngcho cc xc tc thi. Tuy nhin, xc tc thi ch c vi lp vo t ch khi n

khng gy nguy him cho t. V th cn c cc cng on tin x l xc tc thi

trc khi vi lp.

C c nguyn liu

Trn

Chuyn kim loi thnhdng trhoc nnh ha hc cao

Lc

Thu gom cn v i lp

Hn h p t c nhn c bit

Hnh 1.7 S khi cc bc ca qu trnh x l xc tc thi bng phng

php vi lp

Hnh 1.7, ngi ta thm cc tc nhn ha hc chuyn ha cc thnh phn

kim loi trong xc tc thi thnh cc hp phn cc kh tan, khng gy nguy him cho

mi trng.

1.3.9 Th trng v gi c cc kim loi trong xc tc thi HP

Th trng v gi c cc kim loi c trong xc tc thi (Mo, W, Co v Ni)

c ch tm c bit. Alumina c tm quan trng trong cc hot ng lc du,

alkyl ha, Claus, hn ch kh clodo gi c khng qu cao nn thng l vi lphn l thu hi. Tuy vy nhng nm gn y, cc quy trnh ti ch Alumina t xc tc



24/68


HP thi pht trin mnh do gi c n trn th trng tng cao. Cc quy trnh thu hi

cc kim loi t cc xc tc HP hoc cc phng hng hu dng khc c trnh by

trong tt c trong bng tng kt ca cng nghip lc du. D bo rng nhu cu v cc

xc tc HP s tip tc tng khong 4% HT v 8% hydrocracking hng nm. So snh

trn thc t, gi ca xc tc ca HT v hydrocracking ln lt vt qu 10 v 30

USD/kg (2008). Ch rng gi c xc tc ph thuc vo hm lng c kim loi c

trong xc tc v gi c th trng ca cc kim loi.

1.3.9.1 Molybdenum (Mo)

Cng nghip thp l khch hng ln nht ca Mo, khong 75% lng tiu

dng nm 2002 c s dng ch to hp kim thp vi rt nhiu ng dng nh:

tuabin kh, thn my bay, tn la, cc thit b cng ngh ha hcT nm 2000,

thp khng g tng 4-5% mi nm. Cc ng dng khng luyn kim ca Mo tng

khong 3-5% mi nm, chnh l do tng nhu cu xc tc hydro processing. V c

tnh ca nguyn liu, vic m rng v nng cao hiu sut lc du nn nhu cu tiu th

tng. Mt phn Mo c s dng to mui molybdenum sulphide ch to du

bi trn cho xe chy ng xa v nhit cao. Bi nhit nng chy cao (2610oC),

Mo c ng dng lm bng n, thn l nung hoc in cc catot Mo trong ngnh

in. Lng Mo thu hi v ti s dng ca M trong nm 1998 c trnh by chi

tit trong thng k ca Blossom [41].Gi ca Mo tng mnh t gia nm 2002 ti u nm vo khong 12

USD/kg. Thm vo s ng ca m Trung Quc thc y gi tng ln

16USD/kg. Theo hi Price-Waterhouse-Coopers, Mo c mc tng trng quan trong

nht trong nm 2004, tng 209%. Trong giai on ny, gi trung bnh ca Mo khong

14 40 USD/kg. Trong nm 2005, gi vo khong 70USD/kg. D tnh gi s tng

khong 20% nm. Nm 2009, trung bnh khong 40 USD/kg. Nm 2012, tnh trung

bnh ti thng 5 khong 31 USD/kg [43].

1.3.9.2 Cobalt (Co)

Co c s dng trong sn xut siu hp kim ch to tuabin kh v ng

c my bay. Co cng c s dng chng n mn v hp kim chng dnh, thp c

tn s lm vic cao, nam chm, xi mng cacbua v cc dng c kim cng. Co l

thnh phn ca kh nhiu xc tc, n c vai tr quan trng trong cng nghip lc du.

Trong nm 2003, trong lnh vc tiu dng chim 11% lng Co trn th trng [42]

Gi Co kh n nh cho ti nhng nm 1970. Sau tng nhanh ti hn

80USD/kg, bi cc ngun cung cp Co. Sau khi n nh mc 20USD/kg, gi ca



25/68


Co tng ti 60USD/kg vo nhng nm 1990 bi s bt n trong ngoi giao ca cc

quc gia cung cp. Vo nhng nm 1996-1998 c th nhn thy s dao ng v gi

c trn th trng nh sau: 45USD/kg (1996), 40 -50USD/kg (1997), 25-50 USD/kg

(6/1998), 45USD/kg (1998), 50USD/kg (2004), 40 USD/kg (2005), 49 USD/kg

(2009) v 31USD/kg (5/2012) [43].

1.3.9.3 Alumina (Al2O3)

Alumina l thnh phn chnh ca xc tc hydro processing cha hn 70%

khi lng xc tc mi. Ph thuc vo thnh phn m lng alumina trong xc tc

thi vo khong di 60%. Cng phi ch rng lng alumina thu hi t xc tc

thi khng phi l la chn hp dn. Bi vic ch alumina ti ni nu Al th khng

kh thi. Tuy nhin, thu hi alumina tinh khit li c ch trng bi ng dng rng

ri ca n trong cc ngnh cng nghip. Gi ca alumina vo khong 1USD/kg

(2008) v Al vo khong 3USD/kg (5/2012) [43].

1.4 Tng quan qu trnh kh lu hunh trong nhin liu Diesel

1.4.1 Cc quy nh v hm lng lu hunh trong nhin liu

Nhin liu cha lu hunh khi chy s to ra kh thi c cha SOx gy n mn

thit b, gy ma axit v gy c hi cho ngi. Cc hp xc tc khng th x l

c cc kh SOx ny. Do gim thiu cc tc ng xu n sc khe v mi

trng ca kh thi ng c, cn phi gim hm lng lu hunh trong nhin liu.

Cc bng sau y ch ra mt s tiu chun v hm lng lu hunh trong nhin liu

mt s nc tin tin trn th gii [44].

Bng 1.6 Tiu chun chu u v hm lng lu hunh trong nhin liu

Loi nhin liu Nm Hm lng lu hunh (ppm)

Xng

2000 150

2002 2005 < 50

2005 2011 < 10

Diesel

2000 350

2002 2005 < 50

2005 - 2011 < 10

Bng 1.7 Tiu chun M v hm lng lu hunh trong nhin liu



26/68


Nhin liu 2000 2003 2004 2005 2006 2008-2010

Xng 250 < 150 120 90 30 < 5

Diesel 450 250 150 30 15 < 10

Bng 1.8 Cc tiu chun mt s quc gia khc

Quc gia/ Nm 2000 2005 2006

Nht

Triu Tin

c

an Mch

500 ppm

500 ppm

< 15 ppm

< 15 ppm

50 ppm

30 ppm-diesel/ 50 ppm-xng

Hin nay Vit Nam, tiu chun v hm lng lu hunh trong nhin liu

cn rt cao so vi tiu chun cc nc trong khu vc v trn th gii. V d, hm

lng lu hunh trong xng khng ln hn 1500 ppm, trong diesel l khng ln hn

5000 ppm. m bo sc khe cho con ngi, m bo cc tiu chun v mi

trng v hi nhp th bt buc chng ta phi gim hm lng lu hunh trong

nhin liu. Khi tiu chun mi trng ngy cng cht ch v cng thm vic s dng

nguyn liu cha 50% du chua Trung ng cho nh my lc du Dung Qut th

chng ta buc phi s dng cc cng ngh kh lu hunh su. Chnh v vy vic

nghin cu mt cch c h thng cng ngh kh lu hunh nng cao cht lng

nhin liu l yu cu cp bch gp phn chun b cho vic pht trin cng nghip lc

v ha du ca nc ta trong tng lai.

1.4.2 Cc hp cht cha lu hunh trong nhin liu

Cc hp cht c lu hunh c mt trong hu ht cc phn on du th. C

th phn loi cc hp cht ny theo cc nhm chnh nh sau:

Mecaptan (R S H)

Cc hp cht sunphua: R1-S-R2, R1-S-S-R2,R1-S-S--R2

Cc hp cht d vng cha lu hunh: thiophen, benzothiophen v cc dn

xut ca chng.

Trong cc sn phm lc du, cc phn on c nhit si cao hn thng

cha nhiu lu hunh hn v cc hp cht lu hunh thng c phn t lng cao



27/68


hn. Hot tnh ca cc hp cht ny thay i ty theo cu trc ca chng v v tr ca

nguyn t lu hunh trong phn t. Phn on du th c nhit si thp cha ch

yu cc hp cht c lu hunh mch thng: mecaptan, sunphua, disunphua. Cc hp

cht ny rt hot tnh trong cc qu trnh x l hydro hin hnh v chng c th d

dng b loi hon ton khi nhin liu. Cc qu trnh khc nh Merox c th c p

dng chit mecaptan v disunphua ra khi xng v cc phn on nh.

i vi cc phn on du th c nhit si cao hn nh naphta nng chng

ct trc tip, diesel chng ct trc tip v naphta nh FCC, cc hp cht c lu

hunh thng cha cc vng thiophen. Cc hp cht ny gm cc thiophen, cc

benzothiophen v cc dn xut ca chng. Cc hp cht cha vng thiophen ny kh

b chuyn ha hn cc mecaptan v sunfua. Cc phn on nng hn nh naphta

trong sn phm y ca FCC, naphta ca qu trnh cc ha, diesel ca FCC v caqu trnh cc ha thng cha cc hp cht alkylbenzothiophen, dibenzothiophen

(DBT) v cc alkyldibenzothiophen cng nh cc hp cht c lu hunh a vng c

ngha l cc hp cht lu hunh km hot tnh nht trong phn ng HDS.

Trong phng th nghim, vic xc nh tt c cc hp cht lu hunh c mt

trong nhin liu (xng v diesel) l mt vic v cng kh khn v c rt nhiu hp

cht khc nhau. Chnh v vy, ngi ta chn gii php sau y: tin hnh HDS

nhin liu n mt mc kh lu hunh nht nh ri phn tch nh dng cchp cht lu hunh cn li. Kt qu cho thy, i vi xng nh, cc phn t lu

hunh cn li, cha b kh thng l cc hp cht thiophen. i vi diesel, cc hp

cht lu hunh kh b kh nht thng l dibenzothiophen hoc cc dn xut ca

dibenzothiophen. Chnh v vy, i vi cc th nghim HDS su trong phng th

nghim trn cc phn t model, thiophen c la chn nh mt i din ca cc

phn t cha lu hunh c mt trong xng nh cn dibenzothiophen hoc dn xut

ca dibenzothiophen i din cho cc phn t cha lu hunh c mt trong cc phn

on nng hn nh du ha, du diesel. Nghin cu qu trnh HDS su nhin liuchnh l nghin cu qu trnh kh cc hp cht lu hunh kh b kh nht trong

nhin liu. V vy, cn phi tin hnh nghin cu qu trnh HDS trn cc phn t i

din ny trc khi tin hnh nghin cu trn nguyn liu thc.

1.4.3 C ch, ng hc v nhit ng hc ca phn ng HDS

HDS cc hp cht c lu hunh model cng nh nguyn liu thc l i

tng ca rt nhiu nghin cu. V cc iu kin phn ng nh: kiu thit b phn

ng, cht xc tc v thnh phn nguyn liu thay i ty theo tng nghin cu nncc kt qu thu c khng phi lc no cng khp nhau. Tuy nhin, mt vi kt



28/68


lun chung v c ch phn ng v hiu qu ca xc tc c th c a ra da vo

cc s liu c cng b.

Bng 1.9 a ra mt s hp cht lu hunh thng gp trong cc phn on

du m v trong nhin liu nh: mecaptan, sunphua, disunphua thiophen,benzothiophen v cc dn xut alkyl ha ca chng, ng thi trnh by c ch phn

ng HDS c xut. Tt nhin hydro ha kh lu hunh su cc sn phm

lc du, cc hp cht hu c a vng cha lu hunh cng cn c quan tm. Tuy

nhin, do chng bn hn di nhng iu kin HDS hin hnh nn chng ti khng

lit k chng trong bng 1.9 [45].



29/68


Bng 1.9 Cc hp cht c lu hunh in hnh v c ch HDS

Hp cht c lu

hunhC ch phn ng x l bng hydro

Mecaptan R-S-H R-S-H + H2 R-H + H2S

Sulfua

R1-S-R2R1-S-R2 + H2 R1-H + R2-H + H2S

DisulfuaR1-S-S-R2 R1-S-S-R2 + H2 R1-H + R2-H + H2S

Thiophen

S

S

H2 S

-H2S

-H2S

H2

Benzothiophen

S

-H2S

-H2SS

H2

S

H2

H2

Dibenzothiophen

(DBT)

S

S

S S

H2 H2

-H2S

-H2S

H2H2

H2



30/68


Dn xut cadibenzothiophen

(4,6-DMDBT)

SCH3 CH3

SCH3 CH3

CH3 CH3

SCH3 CH3

S

CH3

4,6-DMDBT

SCH3 CH3

CH3 CH3

TH_DMDBT BIPH

HH_DMDBT

CHB

CH3

Cc phn ng HDS l cc phn ng ta nhit v din ra hon ton v mt

nhit ng hc. Phn ng HDS cc hp cht thiophen xy ra theo hai hng. Hng

th nht, nguyn t lu hunh b loi trc tip khi phn t (c ch hydro phn).

Hng th hai, vng thm b hydro ha v sau lu hunh b loi (c ch hydro

ha). C hai xu hng phn ng xy ra song song vi nhau nh s dng cc tm hot

tnh khc nhau trn b mt cht xc tc. Hng phn ng no chim u th ph thuc

vo bn cht ca hp cht cha lu hunh, iu kin phn ng v cht xc tc cs dng. cng nhng iu kin phn ng, dibenzothiophen c xu hng phn ng

qua con ng hydro phn, trong khi , dibenzothiophen b alkyl ha cc v tr

4,6 phn ng theo c hai c ch hydro ha v hydro phn.

Mt hp cht c lu hunh in hnh c trong du m l dibenzo thiophen

S

(DB), cht ny thng c mt trong cc phn on nng hn ca du

m, c mt nhiu trong diesel. Ta tm hiu c ch hydro kh lu hunh ca dibenzothiophen vi h xc tc CoMo/ -Al2O3 trn hnh 1.8 v hnh 1.9



31/68


Hnh 1.8 C ch HDS ca DBT trn xc tc CoMo/-Al2O3

Hnh 1.9 Lng cc cht sau khi tin hnh phn ng HDS [45]

Nh vy trn hnh 1.9 ta thy sn phm biphenyl l sn phm chnh. Do

phn ng:

Dibenzothiophen + H2 Biphenyl + H2S

l phn ng chnh ca qu trnh hydro ha kh lu hunh ca DBT.

Phn ng ny c:

H0298 = - 47,98 kJ/mol



32/68


S0298 = - 51,54 J/mol.K

G0T = - 47,98 + 51,54.10-3.T (kJ/mol)

Bng 1.10 Tc phn ng ca mt s dn xut ca DBT trn xc tc

NiMo/Al2O3 [45]

n v tnh 10-8 mol/g.s

Cht Tc chuyn haTc desunfua

haTc hydro ha

S

Dibenzothiophen

180 157 23

4 metyl

dibenzothiophen

57 24 33

4,6 dimetyl

dibenzothiophen

30 3 27

2,8 dimetyl dibenzo

thiophen

400 - -

1.4.4 Tng quan v xc tc cho phn ng HDS

Ni chung, xc tc cho qu trnh HDS ca ngnh cng nghip lc du l dng

kim loi chuyn tip/cht mang. Cc kim loi chuyn tip 3d, 4d, 5d s dng lm

xc tc kh lu hunh c nghin cu. Hnh 1.10 cho thy hot tnh ca cc kim

loi chuyn tip ny i vi phn ng hydro kh lu hunh. Trn hnh 1.10 ta thy



33/68


cc kim loi qu nh: Ru, Os, Pt, Rh, Re c hot tnh cao hn so vi cc kim loi

nh: Mo, W, Cr, Co, Ni, Fe Tuy nhin, nh chng ta bit th lu hunh l mt

cht gy ng c xc tc rt mnh. Ngi ta kt lun rng xc tc CoMo/cht mang

v NiMo/cht mang sau khi c bin tnh (sunphua ha) th c kh nng chng ng

c tt nht. Do vy hin nay ngi ta tp trung vo nghin cu cc xc tc

CoMo/cht mang, NiMo/cht mang v c th phn tn thm mt hoc mt s kim

loi khc nh: W, Cr, Ga, K tng hot tnh xc tc.

u, nhc im ca mt s xc tc HDS ph bin hin nay:

CoMo: hot ng tt p sut thp, gi thnh r nht

NiMo: hot ng tt p sut hydro cao, thch hp cho qu trnh

hydro ha NiW: t tin, hot ng tt p sut cao, kh sunfua ha

Cc kim loi qu: rt t tin, p dng tt vi hm lng lu hunh

rt thp

Hnh 1.10 Hot tnh ca cc kim loi chuyn tip trong phn ng HDS

Trong cc loi xc tc trn th xc tc CoMo/-Al2O3 c s dng nhiu nht

hin nay v va c gi thnh thp li va c hot tnh cao vi phn ng hydro kh

lu hunh, do n cng c tp trung nghin cu nhiu nht. Hnh 1.11 ch ra cc

dng ca Co, Mo phn tn trn Al2O3 [45].



34/68


Hnh 1.11 Cc dng tn ti ca Co v Mo trong xc tc CoMo/-Al2O3

Hnh 1.11 ch ra rng sau khi sunfua ha to xc tc th Co, Mo tn ti cc

dng coban nitrat, CoMoS, Co9S8, MoS2. Trong ch c 2 dng CoMoS v MoS2 l

c hot tnh cao vi phn ng HDS, cn 2 dng cn li l sn phm khng mong

mun ca qu trnh tm v sunfua ha xc tc.

Khi tin hnh phn ng hydro desunfua ha nguyn liu diesel vi xc tc

CoMo/-Al2O3 ngi ta thu c kt qu th hin trn hnh 1.12 [45].



35/68


Hnh 1.12 Sc k sn phm ca qu trnh hydrodesulfurization cc nguyn

liu diesel trn xc tc CoMo/-Al2O3

Cc cht xc tc thng dng sunphua. S quan tm i vi cc cht xc tc

ny c bt u t trc nhng nm 90 do nhng vn ng c xc tc bi lu

hunh khi tin hnh hydro ha than hoc chuyn ha cc sn phm du m, trong khi

vic loi lu hunh trc khi phn ng xc tc l rt tn km nn mt gii php mi

c a ra: s dng cc sunfua kim loi chuyn tip lm cht xc tc.

Ngay trc v trong chin tranh th gii th hai, cc cht xc tc cha lu

hunh bt u c s dng chuyn ha cc sn phm du m nhng ch n

khong nm 1950, qu trnh x l bng hydro mi thc s pht trin.

Cc cht xc tc l cc sunfua molypden hoc vonfram c kch ng bi

cc sunfua ca cc kim loi nhm VIII, cobalt hoc niken. Cc pha hot tnh ny

c mang trn cc cht mang c din tch b mt ring ln: thng l oxit nhm.

Trong s cc cht mang, -Al2O3 c s dng nhiu nht do c din tch b mt

ring trong khong 170-240 m2/g v th tch l xp trong khong 0,5 0,8 ml/g. Cht

mang oxit silic lun lun km hot tnh hn. Hn hp SiO2 - Al2O3 c tnh axit cao

nn c khuynh hng xc tin s to thnh cc v v th lm cho xc tc rt nhanh b

mt hot tnh.

Cc cht xc tc cng nghip thng dng p n, bi hoc vin. Kch thc

ca cc ht v cu trc l xp ca cc cht mang nh hng n cc tnh cht xc tc

nht l khi tin hnh phn ng trn cc nguyn liu l cc phn on du nng. Cc



36/68


cht xc tc ny cha nhng lng ln pha hot tnh (n 20% trng lng oxit

coban v oxit molypden). Trong cng nghip chng c cung cp di dng oxit ri

c sunfua ha trc tip trong thit b phn ng hoc bi mt qu trnh c tn

SULFICAT.

Phng php thng dng nht iu ch xc tc HDS l phng php tm

mui kim loi ln trn cht mang. Cc mui s dng cn phi tan c trong dung

mi phn tn tt trong khi cht mang v cn phi c phn hy mt cch d

dng chuyn thnh dng trung gian l oxit, ri thnh dng sunfua sau qu trnh

sunfua ha. i vi xc tc cha molypden v vonfram, cc mui thng s dng

nht l amoni paramolypdat v amonimetavonfram. Qu trnh iu ch xc tc gm

cc cng on chnh sau:

Tm mui ln trn cht mang, c th tm ln lt, tm ng thi c hai

mui.

Sy lm bay hi nc

Nung chuyn sang dng oxit

ci thin hot tnh xc tc, tt c cc bc qu trnh ch to xc tc nh

chn tin cht ca pha hot tnh, chn cht mang, quy trnh tng hp v x l xc tc

cn phi c xem xt.1.5 Tnh hnh nghin cu Vit Nam

1.5.1 iu ch

Vit Nam qu trnh hydro ho kh lu hunh c quan tm nghin cu

trong thi gian gn y. C th PGS. TS L Vn Hiu v cc cng s [46] tin

hnh cc nghin cu ch to xc tc NiMo/-Al2O3 cho phn ng ny. Kt qu cho

thy cht mang -Al2O3 c din tch b mt ring l 200 m2/g, ng knh l xp

khong 100 Ao thch hp cho phn ng HDS. Cc tc gi cng a ra c hmlng kim loi thch hp tm ln cht mang trong nghin cu ca mnh, l: 2%

NiO v 12% MoO3, ng thi nhm tc gi c trng c cc tnh cht ca h

xc tc qua cc kt qu phn tch BET, TPR, XRD, SEM, EDS (EDX) v TEM.

Mt s cng trnh nghin cu rt c gi tr na l ca PGS.TS V Th Thu H

v cc cng s [44], [45], [47]. Cc tc gi nghin cu cng ngh hydro ho kh

lu hunh cc hp cht cha lu hunh c mt trong nhin liu (benzothiophen,

dibenzothiophen) s dng xc tc cng nghip. Trn c s cc kt qu thu c, cctc gi tin hnh qu trnh HDS nhin liu diesel c hm lng lu hunh ban u



37/68


l 9500 ppm trn cc xc tc cng nghip . Sau qu trnh HDS, kt qu phn tch

cho thy hm lng lu hunh gim xung ch cn 170 ppm, thp hn nhiu so

vi tiu chun Vit Nam qui nh. Cng trnh cng xut qui trnh cng ngh

HDS su c kh nng thc tin s c t hp trong cc nh my lc du sn xut

cc loi nhin liu c hm lng lu hunh thp p ng cc tiu chun v mi

trng.

Thi gian gn y, nhm tc gi ny nghin cu iu ch xc tc CoMo/-

Al2O3 cho qu trnh HDS [44], [45] v c nhng kt qu ha hn trong vic tng

hp cht mang nhm oxit hot tnh theo phng php mi sol-gel.

Cc kt qu t nhng cng trnh nghin cu trn cho thy vic s dng cc

xc tc c iu ch ti Vit Nam vi cng ngh ca Vit Nam hon ton c kh

nng p ng c yu cu trong cng nghip v cht lng ca sn phm thu c

sau qu trnh HDS tho mn nhng qui nh ngy cng kht khe v nhin liu hin

nay ca Vit Nam v th gii.

1.5.2 Ti ch thu hi kim loi

Hin nay tnh hnh nghin cu ti ch thu hi kim loi qu xc tc thi

nc ta cha thc s thu ht ng mc nhng ta phi xc nh tnh cp thit ca vic

x l xc tc thi khi c thi ra.



38/68


CHNG 2 THC NGHIM

2.1 Tch kim loi Mo, Co v ti ch -Al2O3

2.1.1 Ha cht v dng c

Ha cht

Xc tc thi;

NaOH rn 98%;

Ba(OH)2 rn 98%;

Dung dch BaAl2O4 1M;

Dung dch NH4OH 25%;

HNO3 65%;

H2SO4 98%;

Dung dch (NH4)2SO4 1M;

Dng c

Thit b loi coke;

Thit b nung;

T sy;

My khuy t;

Cc nung;

Cc 500ml, bnh nn 250ml;

a thy tinh, nhit k, giy lc, giy pH;

2.1.2 Quy trnh thc hin

Xc tc thi ban u trc tin c loi coke loi b C, S v mt s tp

cht c th b oxy ha.

Hp cht N NOx

Hp cht S SOx

Hp cht C COx

Sau trn c trn vi NaOH v nung trong t nung.



39/68


MoO2 + 2NaOH + O2 Na2MoO4 + H2O

Al2O3 + 2NaOH 2NaAlO2 + H2O

Cht rn khng tan thu c (hp cht Co v cc tp cht) dng dung dch

HNO3 65% chit ly Co dng dung dch Co(NO3)2 ( thi gian phn ng 4h, tc khuy l 800 rpm).

CoO + 2HNO3 Co(NO3)2 + H2O

Dung dch chit thu c thm BaAl2O4 ( 80oC v thi gian phn ng l 40

pht) sau c tch lng rn.

Na2MoO4 + BaAl2O4 BaMoO4 + 2NaAlO2

Cht rn thu c l BaMoO4 cho thm dung dch (NH4)2SO4 (cng vi cht

tr l H2SO4), lc cht rn BaSO4, ta thu c dung dch mui Amoni Molybdate.

7MoO42- + 8H+ Mo7O246- + 4H2O

6NH4+ + Mo7O246- (NH4)6Mo7O24

Ba2+ + SO42- BaSO4

Dung dch chit thu c sau khi cho BaAl2O4 c thm NH4OH kt ta

Al(OH)3, lc Al(OH)3 sau nung ta thu c -Al2O3.

AlO2- + OH- + 2NH4+ Al(OH)3 + 2NH3

Quy trnh tng quan c trnh by trn hnh 2.1.



40/68


Xc t c thi

Loi cc

Trn

Nung

Ha tan

Tch lng/rn

Dung dch

Tch lng/rn

Aluminat

Lc kt ta

-Al2O3

Lc

BaMoO4

Co/Tp cht

Co(NO3)2

Tch

Mui Amoni Mo

HNO3

(NH4)2SO4

BaSO4NH4OH

BaAl2O4

NaOH

Tp cht

Hnh 2.1 Quy trnh tch Co,Mo v -Al2O3 t xc tc HDS thi

2.2 iu ch xc tc CoMo/-Al2O3

2.2.1 Ha cht v dng c Ha cht

- Al2O3 dng bt (thu hi t xc tc thi)

Mui (NH4)6Mo7O24.4H2O (thu hi t xc tc thi)

Mui Co(NO3)2.6H2O (thu hi t xc tc thi)

Nc ct

Dng c



41/68


a ng mu

Bm ht chn khng

Cc c m

Xilanh v kim nh git

T sy

Thit b nung

2.2.2 Quy trnh thc nghim

Tin hnh iu ch xc tc CoMo/-Al2O3 bng phng php tm kh: tm

ln cht mang -Al2O3 mt lng dung dch mui c th tch bng th tch l xp ca

cht mang. Sau khi tm xong vt liu mang vn c v kh. Sau tin hnh sy mu

110oC trong 2 gi, ri nung nhit 4500C t nht trong 4h.

Dung dch Amoni Molydate Dung dch Cobalt Nitrat

Hn hp sau tm

Hn h p sau sy

CoMo - Al2O3

Sy 110oC

Nung 450oC, 4h

n nh nhit phng trong 5h

-Al2O3

Tm nh git

Hnh 2.2 Quy trnh tm mui Mo, Co ln cht mang - Al2O3

Mt cch c th iu ch xc tc CoMo/-Al2O3 cha 14% MoO3, 3% CoO

cn tin hnh cc bc chnh sau:

+ Chun b dung dch mui (NH4)6Mo7O24.4H2O v Co(NO3)2.6H2O trong nc.

+ Chun b cht mang -Al2O3 (sau khi dc nung 5000C).

+ Cho t t dung dch mui Co v Mo vi th tch bng th tch l xp ca chtmang (v d: s dng 5 g cht mang c Vxp = 1.4 cm3/g th s nh t t 5 1.4 = 7



42/68


cm3 dung dch mui). Trong qu trnh nh dung dch cn phi lc hoc trn u cht

mang dung dch ngm u vo.

+ Sau khi kt thc qu trnh nh git, sy sn phm 110 oC ri nung 4500C

trong 4 gi phn hy cc mui (NH4)6Mo7O24.4H2O v Co(NO3)2.6H2O thnhMoO3 v CoO.

Thc nghim iu ch xc tc

Tin hnh thc nghim iu ch xc tc CoMo/-Al2O3 vi t l CoO/MoO3

nh sau:

Mu 1: CoO 3% v MoO3 18%.

Mu 2: CoO 3%, MoO3 14%.

Mu 3: CoO 3%, MoO3 10%.

Sau khi nh gi hot tnh ca xc tc th nhn thy mu 2 c hot tnh n nh

hn c, gn vi xc tc thng mi.

2.3 Cc phng php ha l c trng tnh cht xc tc

2.3.1 Phng php nhiu x Rnghen (XRD)

Phng php nhiu x Rnghen l mt phng php hin i v c ng

dng mt cch ph bin nghin cu vt liu c cu trc tinh th, nh phng phpny ngi ta c th nhn din nhanh chng v chnh xc cu trc ca mt loi tinh

th ng thi s dng nh lng pha tinh th vi tin cy cao.

Ph nhiu x Rnghen ca cc mu c chp trn my CPM- Bruker D8-

Advance, gc qut thay i t 10-700C, tc qut 0,0050C/pht, ti Trng i

Hc Khoa Khc T Nhin H Ni.

2.3.2 Phng php phn tch cu trc (BET)

Cc cht xc tc d th hin nay s dng trong cng nghip u l vt liu rn

xp. Tnh cht xc tc quyt nh mt phn vo bn cht b mt nh cu trc mao

qun, b mt ring, phn b l xp. nghin cu c trng ca b mt vt liu rn

xp ta cn xt cc i lng sau:

B mt ring ca vt liu: l b mt tnh cho mt n v khi lng (m2/g)

Th tch l xp ring: l khong khng gian rng tnh cho mt n v khi

lng (m3/g)

Phn b kch thc mao qun



43/68


Hnh dng mao qun: mao qun hnh tr, hnh cu, hnh khe, hnh c chai

Qu trnh o b mt ring v phn b l xp ca cc mu nhm hydroxit v -

Al2O3 c thc hin trn my Micromerictics ASAP 2010 ti phng th nghim

cng ngh lc ho du v vt liu xc tc, Khoa Cng Ngh Ha Hc, Trng iHc Bch Khoa H Ni.

2.3.3 Phng php phn tch EDX (EDS)

Phng php phn tch EDX l phng php phn tch hin i dng xc

nh thnh phn (khi lng, nguyn t)ca cc cht c trong hn hp. N ch a ra

thnh phn tng cht nhng khng cung cp dng lin kt hoc cu trc.

Mu c phn tch trn my JSM 6490 JED 2300, JEOL, Nht Bn, ti

Trung tm nh gi h hng vt liu, COMFA Vin Khoa Hc Vt Liu.

2.3.4 Phng php qut cu trc b mt (SEM)

Phng php qut SEM l phng php phn tch hin i dng chp nh

vi cu trc b mt ca vt cn chp vi phn gii cao v su trng quan ln.

Mu c chp nh qua knh hin vi in t qut trn my SEM-JEOL-JSM

5410 LVC (Nht Bn), vi phng i 200 000 ln, ti phng th nghim vt l cht

rn, Trng i Hc Khoa Hc T Nhin-i Hc Quc Gia H Ni.

2.3.5 Phng php pht x hunh quang tia X (XRF)

Phn tch thnh phn nguyn t ca vt liu m khng ph thuc vo lin kt

ha hc ca chng, khng ph v cu trc ca vt liu, thi gian phn thch nhanh

(ch 15 pht ng lot cho kt qu ca cc nguyn t). My o c cc trng thi

mu rt a dng: rn, lng, bt, polymer, mng mng... My pht x hunh quang tia

X c th bn nh lng c tt c cc nguyn t c trong bng tun hon t Natri

ti Uranium.

Mu Diesel sau khi thc hin phn ng HDS s c o bng my XRF ti

Vin Khoa Hc Vt Liu (thuc Vin Khoa Hc Cng Nghip Vit Nam).

2.4 nh gi hot tnh xc tc

Sau khi tng quan ti liu v cn c vo tnh hnh thc t Vit Nam cng

nh cc tiu chun mi trng thi k trung hn v di hn ca Vit Nam v hm

lng lu hunh trong nhin liu, cng ngh kh lu hunh c la chn kho

st l cng ngh hydro ha kh lu hunh su nhin liu diesel trn xc tc CoMo/-



44/68


Al2O3. Trc khi tin hnh phn ng xc tc cn c hot ha chuyn t dng

oxit sang dng sunfua hot tnh.

2.4.1 Sunfua ha xc tc

Trc khi tin hnh phn ng cn tin hnh chuyn xc tc t dng oxit thnhdng sulfua. Giai on sunfua ha rt quan trng v hot tnh ca xc tc ph thuc

vo trng thi sunfua ha ca xc tc v s phn tn ca pha sunfua.

Qu trnh sunfua ha c tin hnh 3800C trong 3h vi hn hp sunfua ha

l H2S/H2. Sau khi hot ha xong, xc tc c thu hi v lu gi trong mi trng

kh tr trnh b oxi ha tr li. Quy trnh hot ho bao gm cc bc sau: cho xc

tc vo trong ng sulfua ho ri cho vo l ra nhit, nng nhit ca l ln n

380

0

C, ng thi thi N2 qua lp xc tc ui ht cc kh v hi nc b hp phtrong xc tc. Sau ng van bnh N2 v m van cc bnh kh H2, H2S, iu chnh

lu lng k sao cho lu lng tng t 4 l/h v lu lng H 2 t 0,6 l/h. Duy tr

nhit ca thit b phn ng 3800C trong 3h, sau h nhit ca thit b v

nhit phng trong khi vn ng thi thi kh N2, ri ly xc tc ra cho vo mt

bnh cha y kh tr Ar lu gi.

2.4.2 Phn ng kh lu hunh diesel

Trn thc t, vic nh gi cc cht xc tc HDS trn nguyn liu thc trong

mt thit b phn ng qui m pilot thng b hn ch bi khi lng xc tc v bi

chi ph lp t h thng phn ng. Hn na, vic phn tch nguyn liu trc v sau

khi phn ng l kh phc tp. Chnh v vy, hu nh cha c cng trnh no cng b

v kt qu nghin cu ng hc ca qu trnh HDS trn nguyn liu thc. Mi y,

do s pht trin mnh m ca k thut thit b phn ng, c s xut hin cc h

thit b micro pilot cho php tin hnh cc phn ng xc tc trong iu kin tng t

nh cc iu kin s dng trong cng nghip. Trong n ny chng ti s dng

h thng micro pilot ny nghin cu qu trnh HDS trn nguyn liu thc.Trong thit b ny, nguyn liu lng c phun trc tip vo trong ng phn

ng trn ln vi kh hydro ri hn hp cht phn ng i qua lp cht xc tc rn

m ti phn ng HDS c din ra. Chnh v vy, h thit b phn ng ny c tn

l h thit b ba pha hay h thit b chy tia. Sau khi ra khi ng phn ng, hn

hp sn phm c a qua thit b tch p sut cao tch sn phm lng v kh

ri cho qua sc k kh phn tch thnh phn sn phm.

Mu diesel thng phm s dng trong nghin cu ny l diesel nhp khuca Petrolimex vi hm lng lu hunh tng ban u l 0,05 % (500 ppm), cht xc



45/68


tc s dng l CoMo/-Al2O3. Cc thc nghim u tin trn nguyn liu diesel lin

quan n vic xc nh bc v hng s tc phn ng tch loi lu hunh. Cc thc

nghim tip theo lin quan n vic xc nh hot tnh ca xc tc cng nh cc

thng s thch hp ca qu trnh HDS su nhin liu diesel.

Hnh 2.3 H thit b phn ng ba pha

Qu trnh th nghim c thc hin trong cc iu kin sau:

- p sut tng thay i trong khong 10 40 bar

- T l hydro/hydrocacbon l 250l/l

- Ty theo mc ch ca thc nghim, nhit phn ng v tc

khng gian (l th tch ca cht phn ng i qua mt n v th tch

xc tc trong thi gian 1 gi - vit tt l VVH) c th thay i.

Hm lng lu hunh trong nguyn liu v trong sn phm phn ng c

xc nh trn my phn tch lu hunh. chuyn ha ca cc hp cht lu hunhtrong diesel c xc nh nh sau:

100S So

XS

=

Trong :



46/68


X: chuyn ha %

S: Hm lng lu hunh tng ban u

So: Hm lng lu hunh cui

Trong trng hp diesel S = 500 ppm



47/68


CHNG 3 KT QU V THO LUN

3.1 Thnh phn xc tc HDS kho st

Xc tc thi l xc tc HDS CoMo/-Al2O3 nhn t Nh My Lc Du DungQut Vit Nam. Xc tc c cc thnh phn ch yu tn ti dng: Co 3O4, CoO,

MoO3, Al2O3, MoS3, Co3S4, S, C [48]. Thnh phn ca mu xc tc thi ban u c

thng bo trong bng sau.

Bng 3.1 Thnh phn xc tc thi kho st [ph lc 3]

Thnh

phnC S O Na Al Co Mo Tng

% Klg 0,35 0,10 37,65 0,23 42,06 7,21 12,40 100

Hnh 3.1 XRD ca mu xc tc thi ban u [ph lc 5]

Nh ta thy khi dng XRD kim tra mu xc tc thi th c ti 76% Al2O3 tn

ti dng syn Al2O3 dng ny th din tch b mt gim, gim hot tnh ca xc

tc HDS. V th mu xc tc ny khng th ti sinh n thun m phi thi b hoc

s dng lm nguyn liu cho cc qu trnh ti ch.



48/68


3.2 Nghin cu cc iu kin thc nghim

3.2.1 iu kin nhit loi coke

Thi gian: 5 h

Nhit : 500 700oC

Bng 3.2 Kt qu thc nghim loi coke [ph lc 3]

Thc nghimNhit

(oC)

Thi gian

(h)

Hm lng Coke (%klg)C S

1 500 5 0,12 0,072 550 5 0,07 0,063 600 5 0,04 0,024 650 5 0,04 0,015 700 5 0,038 0.01

Trong bng 3.2 ta nhn thy rng khong nhit t 550 oC 650oC l thch

hp nht. Hm lng coke v S gim ng k v t ti mc s c mt ca Coke v

S khng nh hng ti kh nng ti ch. Khi nhit ln ti 700oC th hm lng C

c gim xong gim khng ng k. Khng ti u khi ta phi mt kh nhiu nng

lng nng v gi nhit 700oC trong 5h. Nhit ti u l 600oC trong 5h.

3.2.2 Kho st cc yu t lin quan ti ti ch kim loi

3.2.2.1 T l NaOH trn vo xc tc, nhit nung - Phng php nung kh

Th nghim vi 5g xc tc thi loi coke

Thi gian nung l 5h

T l mol Xc tc/NaOH (vi xc tc tnh qua mol Al2O3) : 1/1, 1/2, 1/3, 1/4,

1/5

Nhit : 500 750oC



49/68


Bng 3.3 Kt qu thc nghim phng php nung kh

Thc nghimT l NaOH/Xt

(mol/mol)

Nhit nung

(oC)

Hm lng kim loi thu c

(g)

Co Mo1 1 500 - 0,4572 2 600 0,120 0,4603 3 700 0,230 0,4624 4 750 0,353 0,5735 5 750 0,357 0,573

Qua bng 3.3 ta thy khi nhit tng t 600oC - 750oC th lng Co v Mo

thu c tng nhanh ti 750oC th t kh cao. Khi tng t l NaOH/xt cng khng

tng ng k lng kim loi thu c. Nguyn nhn l do lng Co, Mo thu hi

c t ti hn 90%, lng cn li rt kh thu hi hon ton. Nu tip tc

tng nhit v t l NaOH/xt th khng u vit. Vy ta chn t l NaOH/Xt = 4 v

nhit l 750oC l ti u vi phng php nung kh.

3.2.2.2 Thi gian, nhit ca qu trnh ha tan xc tc NaOH Phng php

thy nhit

T l NaOH/Xt = 4

Nhit : 110 200o

C Thi gian: 2h 5h

Bng 3.4 Kt qu thc hin phng php thy nhit

Thc nghimNhit

(oC)

Thi gian

(h)

Hm lng kim loi thu c

(g)Co Mo

1 110 2 - -

2 150 3 - 0,1403 180 4 0,150 0,3204 200 5 0,163 0,3625 250 6 0,170 0,362

Mt s th nghim khng tnh ton lng Co v Mo l do lng tp cht trong

hn hp qu nhiu. Phi thm mt s cng on khc mi xc nh c (cn Co cn

qu nhiu phi thm bc thm NaOH vo tip tc ha tan Al2O3, thm NH4OH

tch ring Al(OH)3 ) nn tc gi khng kho st. Qua bng 3.4 ta thy nhit

l 200oC v thi gian 5h l ti u vi phng php thy nhit.

So snh 2 phng php:



50/68


So snh 2 phng php nung kh v thy nhit th thy r rng phng php

nung kh c u th hn vi hm lng kim loi thu c ln hn v thi gian ngn

hn. Vi phng php thy nhit, do lng Al2O3 tan t, li qu nhiu cn, mt

khc l phng php ny kh ta gia nhit cao v thc hin phc tp hn. Ta chn

phng php nung kh thu hi v s dng cho cc cng on tip theo.

Hnh 3.2 XRD ca mu xc tc sau khi nung vi NaOH

vi t l mol NaOH/xt = 4, T = 750oC v thi gian nung l 5h [ph lc 6]

Ta thy Mo v Al chuyn i sang dng hp cht d tan: Na 2MoO4.2H2O,

NaAlO2.xH2Oc th dng nc chit tch. Qua d dng loi b c Co

khng tan.

3.2.3 nh hng ca tc khuy ti tinh th BoehmiteTc khuy c kho st trong khong t 30 vng/pht n 100 vng/

pht. Sau mi ln phn ng, tin hnh xc nh tinh th ca sn phm bng

phng php nhiu x tia X (XRD). Cc kt qu c trnh by trong hnh sau:



51/68


Hnh 3.3 nh hng ca tc khuy n s to thnh tinh th

boehmite

Cc kt qu c trnh by trong bng trn cho thy tc khuy thch hp

quy m nh nm trong khong 50 vng/pht. tc khuy thp (< 40 vng/pht)

dng axit v dng aluminat natri trn ln khng u, dn n phn ng axit km.

tc khuy cao (> 80 vng/pht), cc mm tinh th to ra pht trin mnh nn khnng pht trin to boehmite km. Ti tc khuy khong 50 vng/pht, dng axit

v dng nhm aluminat va trn u va n nh cc mm tinh th pht trin

thnh tinh th boehmite. Gi tr tc khuy ny c chn cho cc thc nghim

tip theo.

3.2.4 Kho st thi gian gi ha Boehmite

Thi gian gi ha kt tinh c nh hng ln n kh nng kt tinh ca

boehmite. V nguyn tc thi gian gi ha cng lu tinh th cng cao. Tuy nhin,cng khng nn ko di thi gian gi ha v lm th va tiu tn thi gian va tiu

tn nng lng. Chng ti kho st s nh hng ca thi gian kt tinh n

tinh th ca boehmite. Kt qu c th c th hin trong hnh sau:



52/68


Hnh 3.4 nh hng ca thi gian kt tinh ti tinh th ca Beohmite

Khi thi gian gi ha thp, nhiu mm tinh th cha pht trin ht thnh tinh

th do tinh th thp. khi thi gian gi ha tng, tinh th tng ln. n 120

pht nu tip tc tng thi gian kt tinh th tinh th gn nh khng i. Do vy,

chng ti chn thi gian gi ha thch hp l 120 pht.

3.2.5 nh hng ca pH ti cu trc Boehmite

Trong qu trnh axit ha dung dch aluminat, vi cc pH khc nhau th s

to ra c cc dng khc nhau ca nhm hydroxit. Vi mc ch to ra c nhm

hydroxit dng boehmite c tinh th cao v b mt ring ln, chng ti kho st

pH ca mi trng phn ng ti cc im pH = 7, 8, 8.5, 9, 10. Nu nhm

hydroxit thu c c tinh th boehmite cng cao th - Al2O3 thu c c tinh

khit cng cao v b mt ring cng ln. V vy chng ti kho st nh hng ca

pH thng qua kt qu o b mt ring ca ca mu - Al2O3 thu c. Kt qu thuc th hin hnh 3.5.



53/68


Hnh 3.5 nh hng ca pH n cu trc Boehmite

Qua hnh 3.5 ta thy pH thch hp nht ca qu trnh axit ha to boehmite

l pH = 8,5.

3.2.6 nh hng ca nhit phn ng axit ha n tinh th Boehmite

Bng cch gi nguyn cc iu kin v pH (8-9), tc khuy (50 vng/pht),

thi gian gi ha (2h) chng em tin hnh phn ng ti cc nhit khc nhau: 600C,

700C, 900C, v 1000C. Cc kt qu c trnh by trong hnh sau:

Hnh 3.6 nh hng ca nhit phn ng axit ha n tinh th

boehmite



54/68


nhit di 700 C qu trnh kt tinh boehmite din ra khng hon ton.

tinh cha cao. Tng nhit ln 800C, qu trnh kt tinh din ra tt boehmite kt tinh

gn nh hon ton. Tip tc tng nhit , tinh th ca boehmite khng tng. V

vy nhit thch hp nht l 800C

3.2.7 Kho st ch nung to -Al2O3

Trc khi tin hnh nung mu boehmite chuyn thnh dng - Al2O3 chng

ti tin hnh kho st nhit trng lng v nhit vi sai (TG/DTA) ca mu boehmite.

Kt qu nghin cu c th hin trn hnh 3.7

Qua hnh 3.7, ng TG(ng mu m) ta thy sau khi nung mu mt

khong 30% trng lng, y l lng nc hp ph vt l v nc cu trc mt i.

Trn gin DTA(ng mu nht) ta thy c cc pic c trng ti cc nhit khong 1000C, 2500C v 5000C. Pic ti nhit gn 1000C tng ng vi qu trnh

thu nhit, mt nc hp ph vt l, cn cc pic ti khong 250oC v 500oC c trng

cho mt nhit cu trc xy ra khi chuyn t boehmite sang -Al2O3.

Hnh 3.7 Gin TG/DTA ca boehmite

Da trn gin TG/DTA chng ti chn nhit nung thch hp to ra -

Al2O3 t boehmite l: sy 1000C trong 5 gi, nung 2500C trong 3 gi, nng ln

n 5000C v gi trong 5 gi.

Quy trnh thc nghim tip tc vi 5g xc tc thi thu c 3,26g -Al 2O3 ti

ch t 81,5% -Al2O3. Trn hnh 3.8 ta thy xut hin r nt cc pic c trng ca -Al2O3. Nh vy, -Al2O3 thu c c th s dng lm cht mang cho xc tc.



55/68


Hnh 3.8 Ph XRD mu -Al2O3 ti ch [ph lc 7]

Mu -Al2O3 to ra tiu chun ta c th s dng lm cht mang cho

xc tc HDS.

Hnh 3.9 Mu SEM ca -Al2O3

Ta thy mu -Al2O3 c kch ht kh nh v kh u nhau. Nh th din tch

b mt ca mu kh ln, rt thun li cho vic tm pha hot tnh ln cht mang -

Al2O3.



56/68


Bng 3.5 Thuc tnh ca -Al2O3 ti ch [ph lc 9]

Thuc tnh Din tch b mt Th tch mao qunKch thc mao

qun

Thng s 273,5 m2/g 0,76 cm2/g 103 Ao

Hnh 3.10 ng ng nhit hp ph v nh hp ph theo BET ca - Al2O3

[ph lc 9]

Qua hnh ng nhit hp ph v nh hp ph ta thy khi p sut hp ph tng

th s lm tng dung lng hp ph c. Vi ng hp ph, khi t ti p sut p o,

dung lng hp ph tng ln rt nhanh. Vi ng nh hp ph, khi p sut tng dn

th kh nng nh hp ph gim. Qua ng hp ph ta thy mao qun -Al2O3 khbn vng, thun li cho qu trnh ti sinh nhiu ln xc tc khi xc tc b mt hot

tnh.

3.2.8 nh gi hm lng kim loi thu hi c

Thnh phn mu xc tc sau loi coke tnh theo khi lng (g)

Mu xc tc ly 5g

Loi coke 600o

C/ 5hBng 3.6 Thnh phn mu xc tc sau loi coke [ph lc 3]



57/68


Thnh

phnC S O Na Al Co Mo

g 0,002 0,001 1,89 0,011 2,111 0,362 0,623

Hm lng kim loi thu hi trong thc nghim (g)

Bng 3.7 Hm lng kim loi thu hi trong thc nghim

Thnh

phnC S O Na Al Co Mo

g - - - - 1,73 0,353 0,573

Mu Co thu c dng CoO [ph lc 1]

Hnh 3.11 Hnh nh SEM ca CoO thu c

Hnh 3.12 Ph phn tch EDX mu CoO thu c

Bng 3.8 Thnh phn nguyn t ca mu CoO thu c


100 m100 m100 m100 m100 m


58/68


Thnh

phnC O Na Al Si Ca Co Tng

% Klg 2,35 35,64 0,23 0,36 0,25 0,15 61,02 100

Qua bng thnh phn nguyn t ca mu CoO thu c ta thy rng CoO thu

c c tinh khit rt cao. C th dng to Co(NO3)2 tham gia vo qu trnh

tm ln cht mang -Al2O3.

Mu Mo thu c dng BaMoO4 [ph lc 2]

Hnh 3.13 Hnh nh SEM ca mu BaMoO4 thu c

Hnh 3.14 Ph phn tch EDX mu BaMoO4

Bng 3.9 Thnh phn nguyn t ca mu BaMoO4 thu c


100 m100 m100 m100 m100 m


59/68


60/68


61/68


Hnh 3.17 Xray mu xc tc khi tm Mo v Co ln -Al2O3 [ph lc 8]

Kt qu X-ray cho thy qu trnh tm Co v Mo ln -Al2O3 l kh tt. Hm

lng mui Co tm ln l nh, khng th hin trn gin pic. Nh vy cc giai

on tm, sy, nung khi iu ch xc tc khng lm thay i cu trc xp ca cht

mang.

Kt qu phn tch hm lng nguyn t ca mu xc tc CoMo/-Al2O3 sdng cht mang l nhm oxit iu ch bng phng php kt ta cho thy hm lng

Mo, Co trn thc t v theo l thuyt c s sai khc rt nh v qu trnh iu ch xc

tc l tng i tt.

Bng 3.10 Hm lng nguyn t ca mu xc tc CoMo/-Al2O3 [ph lc 4]

Mu xc tc% Mo % Co

L thuyt Thc t L thuyt Thc t

CoMo/-Al2O3 4,7 4,5 1,0 0,96

Tm li, vi hm lng pha hot tnh l 0,9 - 1% Co v 4 - 5% Mo, qu trnh

iu ch xc tc l tng i tt: cc oxit MoO3 v CoO c phn b ng u trn

cht mang nhm oxit, cu trc xp ca cht mang hu nh khng b thay i v hm

lng pha hot tnh t yu cu lm xc tc cho qu trnh HDS.



62/68


3.2.10 Hot tnh ca xc tc ti phn ng HDS nhin liu Diesel

3.2.10.1 nh hng ca nhit

Kt qu nghin cu s nh hng ca nhit n chuyn ha ca cc

hp cht lu hunh c trnh by trong hnh 3.17.

Hnh 3.18 nh hng ca nhit ti qu trnh kh lu hunh su nhin liu

Diesel

nhit 320

0

C, chuyn ha cc hp cht lu hunh trn xc tc iuch t 24 %. Nng nhit thm 400C, chuyn ha tng n 82 % v hm lng

lu hunh trong nguyn liu gim xung ch cn 90 ppm, thp hn nhiu so vi tiu

chun Vit Nam qui nh hm lng lu hunh trong diesel thi k di hn. Tip tc

nng nhit thm 10K, chuyn ha tng n 90 % v hm lng lu hunh

trong sn phm gim xung 50 ppm. C th thy rng nhit trong khong t 350-

4000C l nhit thch hp cho phn ng HDS su nhin liu diesel. Vng nhit

xc nh tin hnh phn ng HDS ty thuc vo mc ch s dng sn phm cng

nh h thit b dng cho phn ng v cht xc tc dng trong qu trnh. iu ny cth l gii nh sau: nhit qu cao, phn ng cracking to cc trn xc tc c

u tin, phn ng ny bt li cho qu trnh HDS, lm gim thi gian lm vic ca xc

tc. Tri li nhit thp, lin kt C-S ca cc hp cht c lu hunh km hot

ng nh dibenzothiophene v cc dn xut ca n cha b yu i to iu kin thun

li cho phn ng HDS, do phn ng din ra kh khn v khng t hiu sut cng

nh chuyn ha mong mun.

T cc yu t c phn tch trn, chn c nhit thch hp choqu trnh HDS vi xc tc iu ch c l 3600C.



63/68


3.2.10.2 nh hng ca p sut

Hnh 3.19 S ph thuc chuyn ha cc hp cht lu hunh trong diesel

vo p sut lm vic

nghin cu s nh hng ca p sut hydro n qu trnh HDS, phn ng

c tin hnh nhit 3600

C, tc th tch 2 h-1

, p sut thay i trong khong10 30 bar. Cc kt qu thu c c biu din trn hnh 3.20

Nhn thy rng, p sut thp hn 30 bar, khi p sut tng th chuyn ha

cc hp cht lu hunh tng nhanh theo t l gn tuyn tnh. Tuy nhin, bt u t 30

bar, khi p sut tng ln, chuyn ha tng nhanh khng ng k.

iu ny c th gii thch nh sau: p sut tng ln trong ng phn ng l do

vic a kh H2 cng vi dng nhin liu vo, s tng p sut ca ng phn ng bi

H2 c li cho phn ng HDS v mt ng hc. C th, cn bng ca phn ng s dchchuyn v pha to sn phm mong mun ngha l v pha loa d nguyn t. Nguyn

liu cng nng th th p sut hi ring phn ca H2 cng phi ln do p sut chung

ca h cng tng. n mt p sut nht nh th chuyn ha ca cc hp cht

sunfua trong diesel tr nn bo ha, vic tng p sut khng c tc ng r rt n

phn ng na. Vic s dng nhiu hydro ngn cn phn ng to cc nn hot tnh

ca xc tc cng gi c lu hn, sn phm thu c c t mu hn. Tuy nhin theo

quan im kinh t, tit kim cho ph vn hnh th qu trnh cn c tin hnh



64/68


p sut thp nht c th (v chi ph vn hnh tng vi h s 1,5 so vi p sut ca qu

trnh). Chnh v vy, p sut lm vic c la chn trong trng hp ny l 30 bar.

Ta cng xc nh c t s ca H2/nguyn liu l 250l/l. T s ny ph hp

vi p sut c to ra trong ng phn ng cng nh chuyn ha thch hp canguyn liu.

3.2.10.3 So snh hot tnh ca cc cht xc tc

Tin hnh phn ng HDS s dng cht xc tc iu ch c v mt s cht

xc tc cng nghip ti cc iu kin c th nh sau:

Nhit phn ng: 3600C.

p sut phn ng: 30 bar.

Tc khng gian: 2 h-1.

T s H2/nguyn liu l 250l/l.

Lp xc tc l c nh.

H thit b phn ng l h thit b ba pha.

Phn ng ban u c tin hnh trong 10h n nh xc tc, sau

mi thc hin vic ly mu.

Bng 3.11 Kt qu so snh mt s ch tiu quan trng ca nhin liu

trc v sau qu trnh HDS

MuHm lng

lu hunhT trng nht

Ch s

xetan

Diesel ban u 500 ppm 0,84 3,5 cSt 53

Diesel sau phnng (xc tc iu

ch)

90 ppm 0,83 3,4 cSt 55

Diesel sau phn

ng (xc tc cng

nghip)

88 ppm 0,82 3,3 cSt 55

T kt qu so snh trn nhn thy xc tc iu ch c c hot tnh tng

ng vi xc tc i chng dng trong cng nghip.



65/68


3.2.11 Vn mi trng ca quy trnh ti ch

Vic x l v ti ch xc tc thi qu trnh HDS ngoi vic thu ngun li v

kinh t cn c th gim s nhim mi trng do ngun cht thi rn ny sinh ra. V

vy, quy trnh cng ngh phi m bo c cc sn phm khi thi ra mi trngkhng gy nhim mi trng hoc c mc nguy hi nh hn mc nguy hi ca

xc tc thi. Trong qu trnh thu hi kim loi trong xc tc thi b, mt s ha cht

c s dng mt s tc nhn nh: NaOH, HNO3, H2SO4, NH4OH. Tuy nhin c th

thu hi v s dng li chng nhm m bo an ton v mi trng. i vi quy trnh

khng th thu hi th c th s dng tc nhn trung ha nhm to ra mi trng trung

tnh khng gy nguy hi cho mi trng.

S xut quy trnh x l cht thi sau ti ch c a ra hnh 3.20:

Xc t c thi

Loi cc

Trn

Nung

Ha tan

Tch lng/rn

Dung dch

Tch lng/rn

Aluminat

Lc kt ta

-Al2O3

Lc

BaMoO4

Co/Tp cht

Co(NO3)2

Tch

Mui Amoni Mo

HNO3

(NH4)2SO4

BaSO4NH4OH

BaAl2O4

NaOH

B n khoan

ThuhiNaOH

H2O

Thu hi NH3

Tp cht

Hnh 3.20 S x l, thu hi cc cht thi ca quy trnh ti ch



66/68


Ngoi ra th cng cn ch ti qu trnh loi coke cng lm pht sinh cc kh

nh COx, NOx cng l cc kh gy nhim mi trng. Trong iu kin lm trong

phng th nghim, quy m nghin cu th cha cn thu cc kh ny nhng khi s

dng cng ngh vi quy m cng nghip th cn c phng php thu cc kh pht

sinh trong qu trnh loi coke m bo cc quy nh v an ton mi trng.



67/68


CHNG 4 KT LUN

Vi mc ch nghin cu, tng hp h xc tc CoMo/-Al2O3 cho qu trnh

hydro ha kh lu hunh trong nhin liu tn dng t ngun xc tc thi b. n thu c mt s kt qu sau:

tng quan tng c cc kt qu nghin cu mi nht v cc quy trnh cng

ngh ti ch xc tc thi HDS trn Th gii.

ti ch c cc kim loi Co, Mo v ti sinh c -Al2O3 bng phng php

nung kh vi NaOH vi cc iu kin sau:

Loi coke xc tc thi: t = 600oC ; t = 5 gi ;

Nung kh xc tc thi vi NaOH theo t l: Xc tc/NaOH = 1 :4; t =

750oC v thi gian t = 30 pht ;

Tc khuy ti tinh th Boehmite: 50 vng/pht ;

pH trong phn ng axit ha to Boehmite: 8,5 ;

Nhit phn ng axit ha to Boehmite: 80oC ;

Thi gian gi ha Boehmite: 120 pht ;

Nhit thc hin phn ng axit ha to tinh th Boehmite: 80oC ;

Ch nung Boehmite thu -Al2O3:

- Tc gia nhit 10C/pht ;

- Nung 2500C trong 3 gi;

- Nung 5000C v duy tr trong 5 gi;

Hiu sut tch:

- Mo (dng mui Molybdate): 92% ;

- Co (dng mui Cobalt Nitrate): 98%;

- Al (dng -Al2O3 81,5% ): 82%;

Xc nh c cc c trng ha l ca nhm oxit iu ch:

Th tch l xp trung bnh l 0,76 cm3/g;

ng knh l xp khong 103 Ao;



68/68


Din tch b mt ring: ~ 273,5 m2/g.

iu ch c xc tc CoMo/-Al2O3 cho phn ng HDS trn c s nhm oxit

vi thnh phn cc pha hot tnh nh sau: 0,9-1% Co v 4- 5% Mo (14% MoO3 v3%

CoO). tin hnh cc phn ng hydro ha kh lu hunh vi ngun nguyn liu thc

l diesel. V a ra c s nh hng ca cc thng s ca qu trnh n kh nng

tch loi lu hunh i vi nhin liu diesel. iu kin lm vic thch hp c

xut l:

Nhit phn ng: 3600C;

p sut phn ng: 30 bar;

Tc khng gian: 2 h-1;

T s H2/nguyn liu l 250l/l;

cc iu kin lm vic nh trn xc tc iu ch c c hot tnh tng

ng vi xc tc i chng c s dng trong cng nghip.

8 - Do an Shinichi (2!6!2012)_Finish

Documents

Transcript of 8 - Do an Shinichi (2!6!2012)_Finish