PHAN Q N G OXI H O A a-PINEN TREN HE XUC TAG DA OXIT V2O5-ZRO2/MCM-4I OXIDATION OF a-PINEN OVER OXIDE SYSTEM V2O5-ZRO2/MCM-4I

IRAN THI NHLTMAI, NGUYEN THI HA,

NGUYEN THI MINH THU,

Khoa Hod - DH KHTN-DHQG Ha Ngi

NGO QUOC TUAN

Tong Cong ty Hoa ddu Viet Nam

Abstract

V20s-Zr02/MCM-41 catalyst has been prepared, characterzied by by IR, XRD, N2 adsorption, HPT EM, TPR and applied as a bifimctional catalyst to oxidation of a-pinene via a-pinene oxide using O2IH2O2 as an oxidant. Besides main epoxide products, the reaction leads to formation of ally lie oxidation products like verbenol and verbenon. To suppress the formation of byproducts, the control of effects of temperature, time, solvent is essential for conversion of a-pinene to a-pinene oxide.

1. Gidi thieu

a-pinen, la loai hgp chat cd nhieu trong tu nhien. Su oxi hda a-pinen dugc quan tarn Idn bdi cac san pham ciia nd cd nhieu ling dung quan trgng, vi du nhu verbenon, diing de tong hgp taxol, la mot tac nhan dugc ly. Con cac san ph^m tecpenic andehyt, rugu, este va epoxi dugc xem nhu cac cha't dau lam dugc pham, tao ra nude hoa, cha't tao huong...Dac biet la cac chat epoxi dugc diing rdng rai nhu la

997

cac nguyen lieu thd cho cac loai nhua epoxi, sou, uao L/iyi n* ^..„i .xv.«i dgng be mat, lam chat phu gia chdng oxi hoa hoac phu gia cue ap va cac chat trung gian trong tong hgp hiru ca tinh khiet [1,2,3,4].

Trong hda hoc tecpen, su epoxi hoa chgn Igc la ra't quan trgng. Cac chat oxi hoa theo ti le hgp thiic dung cho phan ling thudng la cac peaxit hiru ca, phuang phap nay tao ra nhieu san pham phe thai, han nira khdng chgn Igc vdi cac epoxi nhay axit. Tranh hien tugng nay, nhieu nghien ciiu che tao he xuc tac khac nhau nhu cac hgp chat ciia vonfram, xiic tac nhdm silicat mang titan, peroxovonframphotphat, molypden, phiic vanadi, mangan,... da dugc sir dung cho nhieu mii"c do thanh cdng cung nhu la han che khac nhau. Nghien cu:u tim hieu kha nang oxi hoa chgn Igc tao cac san pham oxi hoa rieng biet a-pinen la va'n de it dugc thuc hien d Viet Nam. Trong cdng nghe che tao phu gia, chat boat dgng be mat, nhi6u tac gia mudn thuc hien qua trinh epoxi hoa hoac hidroxi hda cac hgp chat chiia nd'i ddi tao ra cac san pham cd gia tri ling dung mdi. Qua trinh oxi hoa olefin tren cac he xiic tac khac nhau dang thu hiit nhieu tac gia tren the gidi quan tarn [2,6] do san pham da dang, phirc tap, vi vay viec tim dugc he xdc tac cd hieu qua, chgn Igc... la di6u can thie't. He vat lieu da kim loai oxit vdi nhieu hieu irng va nhiing tinh nang xiic tac mdi hien dang dugc chii y. Vanadi oxit dugc quan tam khi che tao to hcfp vdi cac oxit kim loai khac de tao ra xiic tac vdi cac hieu ling mdi. Trong nghien ciiu nay thuc hien che tao he xiic tac V205-Zr02/MCM-41, nghien ciiu dac trung vat ly tinh chat xiic tac da oxit va mdi quan he giira ca'u true va tinh chat ciia qua trinh oxi hoa a-pinen nham tim ra nhiing di6u kifen chgn Igc cho san pham a-pinenoxit.

2. Thi/c nghiem

Mau MCM-41 dugc tong hgp tii tetraetylorthosilicat Si(OC2H5)4va chat hoat dgng be mat BRIF-56 la xetylpolietilenoxit C,6H33(OC2H4),oOH: Chat hoat dgng be mat khdng ion xetylpolietilenoxit BRIJ-56 dugc hoa tan trong lugng nude cat vira dii. Sau dd dugc them vao lugng amoniac du de tao mdi trudng kiem (pH~9). Dung dich nguon Silic dung de tong hgp (thuy tinh long, tetraorthosilicat TEOS...) dugc nho

998

tut tii v^o dung dich cha't hoat ddng be mat cr trSn, ddng thdi khua'y manh trong 2 gid. K6't qua thu dugc gel mau trang due, Igc san ph^m thu dugc bang cdn dS'n mdi trudng pH~7. Sa'y khd san phdm qua dem d 90''C va sau dd nung d 550°C trong 4 gid de loai cha't tao ca'u triic thu dugc bgt min, xd'p.

Tien hanh dua oxit ciia vanadi va zirconi len vat lieu MCM-41 da tong hgp dugc. Ham lugng phiic ciia vanadi (vanadioxalat) hoac amonivanadat dugc tinh toan dii de che tao ra he 10%V2O5 -10%Zro2/MCM-41 dugc tam vao lugng 10% Zr02 tren MCM-41 da di^u ch6' d tren, de yen 24 gid d nhiet do phdng, sa'y khd d 120"C trong 6 gid va hoat hoa d 450''C trong 3 gid.

Xiic tac sau khi dugc xir ly hai nude dugc nghien ciiu trang thai phan tan ciia cac oxit tren MCM-41 bang phuang phap khir H2 theo chuang trinh nhiet do; nhilu xa tia X trong viing gdc hep, pho hong ngoai, do ha'p phu nita tren may ASAP 2010 (Micromeritics Autochem II-USA) d nhiet do 77 K; hien vi dien tir truyen qua phan giai cao dugc chup tren may JEM 1010 d hieu dien the 80-110 KV. Phuang phap khir hoa theo chuang trinh nhiet do dugc diing de nghien ciiu trang thai oxy hoa khir ciia be mat va khdi chat ran. Qua trinh khir hoa dugc tien hanh tren may AutoChem II 2920 Micromeritics. Phan ling epoxi hoa a-pinen tren xiic tac 10%V2O5-ZrO2/MCM-41 dugc thuc hien trong pha long. Ket qua phan ling dugc phan tich tren he may GCMS, HP 6890.

3. Ket qua va thao luan

MCM-41 thudc ho vat lieu mao quan trung binh MS-41S cd cau triic luc lang. Vat lieu MCM-41 cd dudng cong ha'p phu-giai hap N2 ma theo su phan loai ciia lUPAC la dang dudng dang nhiet ha'p phu-khir ha'p phu ling vdi VLMQ. Dudng cong nay cd vdng tre la dudng cong dac trung cho VLMQTB cd kich thudc mao quan tiir 20-500A. Dudng phan bd kfch thudc mao quan ciia miu cho ta thay dudng kinh

O

mao quan trung binh ban dau la 38A, sau khi dua cac oxit kim loai len O

giam cdn 30A. Viec mang cac oxit len MCM-41 dugc nghien ciiu bang phuang phap khir hoa H2 theo chuang trinh nhiet do. Phuang

999

khdi chat rdn. Ket qua tren gian dd kuu mcu i.-uuvjiig im.n imxy,. ^y ,.,«« mau 10%V2O5-ZrO2/MCM-41, cho thay hai pic d nhiet do thap han la 510"C va pic d 430"C tuang irng vdi qua trinh khir V5+ — - V4+ va V4+ — - V3+, va phan anh su ciing ton tai ciia hai dang monovanadat biet lap (VOJ va polyvanadat ([VOJ)[2,3]. Difeu nay cho tha'y: Khi ham lugng vanadioxit phan tan thap vao mao quan MCM-41 cd kha nang dat trang thai dan lap va ton tai d dang monovanadat biet lap (VO^) va polyvanadat ([VOJ). Chinh sir phan tan deu tren be mat Zr02 -SiO 2 nen nd d6 bi khir, la hai dang ton tai nay ciia vanadioxit c6 kha nang lam xiic tac tot va cd tinh chat rieng biet cho qua trinh oxi hoa. Tren gian dd khdng thay xuat hien pic khir dac trung cho ZrOz, chiing to trong viing nhiet do nghien ciiu, ZrOjChua bi khir.

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700

650

600

550

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500 "o"

4 5 0 ^

.400

350

^300

30 35 ^0 45 50 '\\\ii\ g j a P (h) 70 75 80 B6

Hiiihl: Phuang phap khu hod theo chuang trinh nhiet do cua mau lOVZIMCM-41

Anh hirdng cua cac dieu Men phan litig oxi hoa a-pinen tren cac he xuc tac hon hgp oxit Zr02-V20s tren vat lieu MQTB.

Phan ling oxi hoa a-pinen la mot phan irng khd kiem soat, va cho san pham vd ciing phiic tap. Ngoai ban chat xiic tac, cac dieu kien phan ling ve nhiet do, chat oxi hoa, dung mdi... deu anh hudng den ket qua phan ling. Vdi mong mudn che tao ra vat lieu cd hieu qua xuc tac chgn Igc san pham epoxi, dieu kien tong hgp xuc tac va phan ling

1000

ket qua phan ling. Vdi mong mudn che tao ra vat lieu cd hieu qua xiic tac chgn Igc san pham epoxi, dieu kien tong hgp xuc tac va phan ting da dugc khao sat. Phan ling oxi hoa a-pinen bang tac nhan O2/H2O2 di6n ra theo hai hudng quan trgng: epoxi hda va oxi hoa allyl. Phan ling epoxi lien quan den su tan cdng electiophin vao ndi ddi, trong khi phan ling oxi hoa d vi tri allyl la ket qua cua sir the hidroxi [4,7,10]. Cac hudng san pham phu thudc vao trang thai hoat ddng, tuang tac be mat, luc axit ciia xiic tac, dieu kien phan irng va kich thudc ciia epoxi, dac biet hoat tinh oxi hoa ciia xiic tac, lire axit, dung mdi, nhiet do phan ling anh hudng Idn den qua trinh ddng phan hoa san pham tao ra. Cac san pham cd the thu dugc tu' qua trinh oxi hoa a-pinen la: Verbenol, verbenon, a-pinen oxit, campholenandehit, trans-carveol, isopinocampheol, trans-sobreol, p-xymen... [1, 8,9,10,11,12].

Anh hitcing cua nhiet do phan ung tol phan ung oxi hoa a -pinen Trong cac phan ii:ng hoa hgc thi nhiet do ludn la mot yeu to anh

hudng quan trgng den tinh chat san pham phan ling... dac biet ddi vdi phan ling cd nhieu hudng va cac hudng phu thudc nhieu vao nhiet do. Phan ling thuc hien trong khoang nhiet 50"C-100"C.

Bang 1: Anh hudng cua nhiet do phan irng tdi phan ling oxi hoa

a-pinen

Nhiet do ("c) •

50

60

80

100

Do chuye'n hoa a-pinen(%)

-

6,73

25,64

25,77

Thanh phan san pham chuyen hoa(%)

Verbenol

-

30,28

29,85

25,14

Verbenon

-

6,55

17,00

26,37

a-pinenoxit

-

45,44

43,39

28,31

San pham khac (campholenandehit, trans-carveol...)

-

28,31

9,76

20,18

Nhiet do anh hudng nhieu de'n tinh chat ciia san pham oxi hoa. 6 nhiet do 50"C, phan ling hau nhu khdng xay ra, xiic tac chua cd hoat tinh d nhiet do tha'p. Tang nhiet do, kha nang phan irng tang len. Khi tang len 60°C, xuat hien ddng thdi ciia ca hai hudng phan ung oxi

1001

hoa a-pinen: a-pinen oxit; Verbenol va verbenon... tnann pnan epoxi chiem uu the. Khi tang nhiet do len 80"C, do chuyen hoa a-pinen tang, san pham cdng va the' deu tang. Han nira, nhiet do tang, san pham verbenol giam dan thay vao dd la sir tang len ciia verbenon, dieu dd cho thay d nhiet do cao han, verbenon cd the la san ph^m oxi hoa Ian lugt qua giai doan tao verbenol, hoac la san pham oxi hoa sau han, va kha nang chuyen hoa a-pinen cang tang theo nhiet do. San pham epoxi giam dan, trong khi dd cac san ph^m khac nhu campholenandehit, trans-carveol... tao thanh nhieu han, cd the a nhiet do cao han 80"C, a-pinen oxit tao thanh bi ddng phan hda tao ra cac san pham sap xep lai vdng a-pinen oxit la campholenandehit, trans-carveol... San pham campholenandehit la san pham ddng phan hoa vdng oxiran d ciing dieu kien khi dung xiic tac cd tinh axit Lewis cdn san pham trans-carveol la san pham thu dugc khi ddng phan hoa a-pinen oxit dudi tac dung cua cac tam axit Bronsted tren xiic tac [4,7,9].

Anh huang cua thdi gian phan ling tdi phan ling oxi hoa a -pinen Viec nghien ciiu anh hudng cua thdi gian cho thay mot so thong

tin ve kha nang chuyen hoa so ca'p va thii ca'p. Day cung la nhiing thong so quan trgng de dinh hudng san pham mong mudn.

Thai gian (gia)

0,5

1

2

7

Do chuyen hoa a-pinen (%)

9,47

23,1

25,64

29,17

Thanh phan san pham chuyen hoa (%)

Verbenol

43,72

40,28

29,85

23,13

Verbenon

2,13

6,55

17,00

28,38

a-pinenoxit

49,44

45,44

43,39

18,31

San phalm khac (campholenandehit,

trans-carveol...) 4,71

7,73

9,76

30,18

Bang 2: Anh hudng cua thdi gian phan urng tdi phan iirng oxi hoa

a -pinen

Dudi ciing di6u kien xiic tac, nhiet do,... cho tha'y do chuyen hoa

ciia phan ling oxi hoa a-pinen tang khi thdi gian tang. Su tang nhay

1002

vgt khi thdi gian tang tir 0,5 gid len 1 gid, lugng a-pinen chuyen hoa cang tang cao. Song song vdi su tang do chuyen hoa cho thay san phdm campholenandehit, trans-carveol... cung tang len, chii'ng to la theo thdi gian, cac san phdm chuyen hoa thii cap ciia a-pinen oxit cung tarig len. Tuang tu san pham oxi hoa allylic cung tang dan, va su giam cua verbenol tuang irng vdi sir tang ciia san pham verbenon-san pham oxi hoa thii ca'p ciia verbenol theo thdi gian. Ban chat xiic tac, cac dieu kien nhiet do, thdi gian deu anh hudng tdi tinh chat san ph^m, ben canh dd dung mdi cung la mot ye'u to quan trgng anh hudng de'n phan ii'ng. dieu nay se dugc thao luan trong cac nghien ciru tie'p theo.

Tir san pham thu dugc va cac thdng tin vat ly ciia xiic tac, cho thay phan ling oxi hoa a-pinen tren ciing he xiic tac V205-Zr02/MCM-41, trong cung dieu kien nhiet do, thdi gian phan irng, tdc do ddng khdng khi, trong ti le a-pinen: HjOj la 10:1 ludn dien ra theo hai hudng song song. Va san pham thu dugc theo so dd sau:

the hidroxi

tj-pinsne

epoxi hoa

OH

verbenol

i verbenone

. <

"J a-ptneni oxit

.OH

HjO/H- / / X N,

•• / H' \ HjO/H'

-OH

1.2-pinarMdio) -.i*^'^- ./'('"OH

trans carveol trans sobrero!

isopinocampheol

v tam axit

" ^

. O

isopinocamphone

\ / O campholen>c aidehyt

\

•A / k

Isomefic aldehyde

1003

Hinli 2: Sa do tong qudt ciia qua trlnn cnuycn nuu Lx.-;yt/ic#. .< <,,. „y ..vm. .m. 1 OWoV^Os-ZrOJ MCM-41

Cac tac gia trudc day khi thuc hien phan ling oxi hoa a-pinen bang tac nhan H2O2 tren cac he xiic tac khac chi thu dugc san pham hidroxyl, hau nhu khdng thu dugc san pham epoxi trung gian [4,7]. Cac san pham epoxi hoa trung gian de dang bi ddng phan hoa bdi tam axit Bronsted hoac axit Lewis cd mat tren be mat xiic tac oxit tao ra nhieu san pham khac nhu 1,2-pinancol, trans-carveol, trans-soberol, campholendehyt... Vdi su han che' tao san pham ddng phan hoa va tren ca sd thuc hien khir hoa Hj ciia mau xiic tac cho thay VjOj-ZrOj phan tan tren nen SiOj trong MCM-41 cho thay tinh cha't vat lieu khac so vdi cac tac gia trudc khi mang V2O5 ciing vdi Ti02, ket qua khii Hj theo chuang tinh nhiet do xuat hien cac pic khir tha'p han so vdi he V2O5 -TiOj dac trung cho su ton tai d hai dang monovanadat biet Mp (VOJ va polyvanadat ([VOJ) tren cha't nen khdng mang tinh axit [2,3]. Su to hgp oxit V2O5 vdi Zr02 tao ra mot he vat lieu cd luc axit yeu xiic tac chgn Igc cho qua trinh oxi hoa a-pinen tao thanh a-pinen oxit. Tir cac ke't qiia tren cho phep dinh hudng cac nghien ciiu tie'p che tao vat lieu oxit cd hieu qua cao ddi vdi qua trinh oxi hoa rieng biet.

4. Ket luan

Da tong hgp ra vat lieu mao quan trung binh MCM-41 va thanh cdng trong viec dua cac oxit lim loai vanadi va zirconi len vat lieu mesopo. Vat lieu tong hgp dugc dugc nghien ciiu dac trung vat ly bang phuang phap khir hoa H2 theo chuang trinh nhiet do. Phan ling oxi hoa a-pinen cho do chgn Igc a-pinen oxit va do chuyen a-pinen hoa td't tren xiic tac 10%V2O5-ZrO2/MCM-41.

Tai lieu tham khao

1. Oxana A. Kholdeeva, Tatiana A. Trubitsina, Maria N. Timofeeva, Gennadii M. Maksimov, Raisa I. Maksimovskaya, Vladimir A. Rogov (2005). The role of protons in cyclohexene oxidation with H2O2 catalysed by Ti(N)-monosubstituted Keggin polyoxometalate, Journal of Molecular Catalysis A: Chemical, 232, pp.173-178.

1004

2. Pham Thanh Huyen, Hoang Trgng Yem, Dao Van Tudng (2003). Influence of some transition metal oxides on the properties of vanadialtitania catalyts for the oxidation of toluen, EP073, 10"" Asian Chemical Congress, S"* Eurasia Conference on Chemical Sciences, 2003.

3. Nguyen Van Hoa, Nguyln Hiru Phii. Nghien ciiu cau true he xuc tac WjOsfTiOj bang mot sd phuang phap phd (2003). Hoi nghi hoa hgc toan qudc Ian thii IV, Ha Ndi-Viet Nam, 2003.

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5. V. Gonzalez-Pena, C. Marquez-Alvarez, I. Diaz, M. Grande, T. Blasco, J. Perez-Pariente (2005). Sol-gel synthesis of mesostructured aluminas from chemically modified aluminum sec-butoxide using non-ionic suifactant templating, Microporous and Mesoporous Materials, 80, pp.173-182.

6. P. Oliveira, A.M. Ramos, I. Fonseca, A. Botelho do Rego, J. Vital (2005). Oxidation of limonene over carbon anchored transition metal Schiff base complexes: Effect of the linking agent. Catalysis Today, in press.

1. Peng Wu, Yueming Liu, Minyuan He, Takashi Tatsumi (2004). A novel titanosilicate with MWW strctiirc C ' 'lytic Properties in selective epoxidation of diallyl ethei with jdrogen peroxide, Joiwnal of Catalysis, 228, pp.183-191.

8. Markus Klawonn, Man Kin Tse, Santosh Bhor, Christian Dobler, Matthias Beller (2004). A convenient ruthenium-catalyzed alkene epoxidation with hydrogen peroxide as oxidant, Journal of Molecular Catalysis A: Chemical, 218, pp.13-19.

9. Paul A. FitzGerald, Matthew W. Carr, Tim W. Davey, Algirdas K. Serelis, Chris H. Such, and Gregory G. Warr (2004). Preparation and dilute solution properties of model gemini nonionic swfactants. Journal of Colloid and Interface Science,

1005

275, pp.649-658.

10. Matteo Guidotti, Nicoletta Ravasio, Rinaldo Psaro, Giovanni Ferraris, and Giuliano Moretti (2003). Epoxidation on titanium-containing silicates: do structural features really affect the catalytic performance, Journal of Catalysis, 214, pp.242-250.

11. P.A. Robles-Dutenhefner, M.J. da Silva, L.S. Sales, E.M.B. Sousa, E.V. Gusevskaya (2004). Solvent-free liguyd-phase autoxidation of monoterpenes catalyzed by sol-sel ColSiO^. Journal of Molecular Catalysis A: Chemical, 217, pp.139-144.

12. Matteo Guidotti, Nicoletta Ravasio, Rinaldo Psaro, Giovanni Ferraris, and Giuliano Moretti (2003). Epoxidation on titanium-containing silicates: do structural features really affect the catalytic performance, Journal of Catalysis, 214, pp.242-250.

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