DRL No. 161 DRD L h e Item No. SE-2

DOE/JPL 956061- 6 Distribution Category UC-63

FLAT-PLATt SOLAR ARRAY PROJECT ADVANCED MATERIALS RESEARCH TASK

Q U A R T E R L Y R E P O R T

INVESTIGATION OF THE HYDROCHLORINATION OF SrCq

(Covering the Period October 9, 1982 to Januery 8, 1983.)

JPL CONTRACT N O , 956061

T O

JET PROPULSION LABORATORY C A L I F O R N I A I N S T I T U T E OF TECHNOLOGY

BY

J E F F R E Y Y , P , MU1

January 18, 1983, n r n r I r n

(NASA-CR-17C235) I N Y E S I I G A T I C 6 C E 'THE NE:-23699 HYCRCCHKCRIEBTICN CF S i c 1 0 C u a r t c r l j Report, 9 Cct. 1982 - 8 Jar. lC , f3 (So lare lec tron ics , Inc.) 45 F HC L C 3 / P l F A C I Unclar

CSCL 10A G 3 / I ( U C 3 4 1 5

The JPL Flat-Plate Solar Array Projec'L is sponsored by the U. S . Pepartment of Energy and forms part of the Solar Photovoltaic Conversion Program t o in i t ia te a major e f fort toward the develop- ment of low-cost solar arrays. T h i s work was performed for the Jet Propulsion Laboratory, California Institute of Technology by agreement between NASA and DOE.

S O L A R E L E C T R O N I G S , I N C , P . O . B@X 141, BELLINGHAM, MASS. 02019

FLAT-PLATE SOLAR ARRAY PROJECT

ADVANCED MATERIALS RESEARCH TASK

"Invest igat ion of the Hydrochlorination o f SiC14"

SIXTH QUAR!i!ERLY REPORT

January 18, 1983. hY

J e f f r e y Y. P. hi

SOLARELECTRONICS, INC. Bellingham, Mass.

ABSTRACT

A bas ic , experimental study on the hydrochlorination of s i l i c o n t e t r a c h l o r i l e and meta l lurg ica l grade s i l i c o n w i t h hydrogen gas t o form t r i c h l o r o s i l a n e has been ca r r i ed out t o g r e a t l y expand the range of reac t ion conditions. These r eac t ion k i n e t i c measuremen;s were reported i n previous Quar t e r ly Reports. During t h i s qua r t e re the equilibrium constant, K f o r t h e hydrochlorination reac t ion w a s measured as a funct ion of tem- perature, pressure and concentration. The v a r i a t i o n of t h e equilibrium constant as a funct ion of temperature provided the measurement on the heat of reac t ion ,AH, by the Second Law Method. The value ofAH was measured t o give 10.6 Kca;/mole. The equilibrium c m s t a n t w a s a l s o s tud ie s as a functior, o f concentration, In agreement w i t h t he theory, the equilibrium c m s t a n t remained ccinstant w i t h respect t o the varying H2/S iC14 feed ratios. On the other hand, the e f f e c t of pressure on the equilibrium constant was found t o be more complex. A t the lower pressure range o f 25 psig t o 100 psig, t he equilibrium constant remained constant within experimental e r ro r . However, a t t h e

higher pressure range of 150 ps ig t o 500 psig, t he equilibrium cmc',ant showed a much higher value. T h i s phenomenon is not

P'

i

fully understood at the present time.

Previous kinetic modeling of the hydrochlorination reaction has shown that the experimental rate data obeyed a psuedo-first order kinetics. The rate constant, kl, for the psuedo-first order rate equation was then measured as a function of temperature, pressure and concentration. The variation of the rate constaqts as a function of temperature provided the measurement on the activation energy,&& which was reported in the last Quarterly Report to give a value of 13.2 Kcal/mole. The effect of pressure on the rate constant was studied this quarter. The rate constant, kl, decreases as a function of increasing pressure. On the other hand, the concentration (HJSiC1, feed ratio) shows a small effect on the reaction rate. The rate constant slightly increases at a higher H,/SiC14 feed ratio. An attempt to develop a generalized rate equation applicable to the entire range of reaction conditions is in progress.

Construction of the quartz hydrochlorination reactor system has been completed. This quartz reactor is designed for the deuterium kinetic isotope effect study. The reactor system has been successfully started up. Some preliminary experiments on the deuterium kinetic isotope effects were carried out. More experi- mental work is in progress.

ii

TABLE OF CONTENTS PaRe No.

ABSTRACT i

TABLE OF CONTENTS iii

I INTRODUCTION

11. DISCUSSION A. Equilibrium Constant Measurements

(1) Equilibrium Constant as a Function of Temperature

(2 ) Heat of Reaction,AH (3 ) EQuilibrium Constant as I Function o f

Concentration ( 4 ) Equilibrium Constant as a Function of

Pres sure

1

1 1

4

4

B. Rate Constant Measurements 5 (1) Rate Constant as a Function of Temperature 6 ( 2 ) Rate Constant as t. Function of Concentration 6 ( 3 ) Rate Constant as a Function of Pressure 7

C. Reaction Mechanism Study 8 9 (1) The Quar tz Hydrochlorination Reactor

D. Summary o f Progress 9

111. PROJECTED SEvENTH QU4RTER ACTIVITIES 10

I V . REFERENCES 10

V. APPENDIX Program Plan Table I Equilibrium Composition of Chlorosilane Products

a t 100 psig, H2/SiCllt of 2.0 and a t Various Temperatures

Table I1 Equilibrium Constants a t Various Temperatures Table I11 Equilibrium Constants a t Various H2/SiC14

Table I V

Table V

Feed Ratios Equilibrium Constants a t 5OO.C and a t Various Pressures and H,/SiC14 Feed Ratios Equilibrium Constants a t 45OoC and a t Various Pressures and H,/SiC14 Feed Rat ios

i ii

Table V I

Table V I 1 Rate ConstaiLt a t 100 psig, SOO'C and H2/SiC14 = 4.0 Table V I 1 1 Rate Constant at 100 psig, SOO'C and H2/SiC14= 2.8 Table I X Rate Constant. a t 100 psig, 500'C and H,/SiC14 = 2.0 Table X Rate Constant a t 100 psig, 5OO'C and H2/SiC14 = 1.0 Table X I Summary of Rate Constants a t 100 psig, 500'C and

a t Various H,/SiC14 Feed Rat ios Table X I 1 Rate Constant a t 25 psig, 500'C and H2/SiC14 = 2.0 Table X I I I Rate Constant a t 100 psig, 5OO'C and H2/SiC14 = 2.0 Table X I V Rate Constant a t 200 psig, 500'C and H2/SiC14 = 2.0 Table XV

Figure I P l o t of t h e Van't Hoff Equation Figure I1

Figure I11 Plo: of t h e Psuedo-First Order Rate Equation, 100 psig,

Figure I V P lo t o f t h e Psuedo-First Order Rate Equation,

Figure V Plot of t h e Psuedo-First Order Rate Equation

Figure V I P lo t of t h e Psuedo-First Order Rate Equation

Figure V I 1 P lo t of t he Psuedo-First Order Rate Equation

Figure V I 1 1 Hydrochlorination o f Sic14 and M.G. S i l i c o n a t 500'C, H,/SiC14 = 2.0 and a t Various Pressures

Figure I X Plot o f t h e Psuedo-First Order Rate Equation 25 p s i g , 500'C and H2/SiC14 Feed Ratio of 2.0

Figure X P l o t o f t h e PFuedo-First Order Rate Equation 100 psig, 500 C and H2/SiC14 Feed Rat io of 2.0

Figure X I P l o t of t h e Psuedo-First Order Rate Equation

Figure X I 1 P lo t o f kl versus Pressure Figure X I 1 1 Schematic o f t he Quar tz Hydrochlorination Reactor

Rate Constant a t 100 psig, SOO'C and H,/SiC14 Feed Ratio of 4.7

Summary o f Rate Constants a t 5OO'C and a t Various H2/SiC14 Feed Rat ios and Pressures

Hydrochlorination of SiClg and M.G. S i l i c o n a t 100 psig, 500°C and a t Various H2/SiC14 Feed Rat ios

500 C and H2/SiC14 Feed Ratio o f 4.7

100 psig, 500'C and HZ/SiC14 Feed Rat io of 4.0

100 psig, 500°C and H2/SiC14 Feed Rat io o f 2.8

100 psig, 500°C pad H2/SiC14 Feed Rat io of 2.0

100 psig, 500'C and H2/SiC14 Feed Rat io o f 1.0

200 psig, 500°C and E2/SiC14 Feed Rat: '0 o f 2.0

i v

I. INTRODUCTION

A basic research and development program has been carried out to study the hydrochlorination of SX14 and metallurgical grade (m.g.) silicon to form SiHCl The hydrochlorination re- action was shown to be an efficient process for the production of trichlorosilane which is an important starting material for the manufacturing of high purity, electronic grade silicon metal. Experimental work was carried out in accordance with the SC-I Program Plan in the Appendix. The laboratory study was exnanded to include a wide range of reaction conditions. These additional reaction kinetic measurements provided the needed experimental data for the subsequent theoretical studies to develop a rate equation for the hydrochlorination reaction and to provide a basic understanding on the reaction mechanism. This Quarterly Report is the sixth in the series. Activities in this quarter includes the equilibrium constant and the rate constant measure- ments as a function of temperature, pressure and concentration. Thermodynamic functions, such as AH, are alto determined from these experimental data. Results are summarized in the following discussion.

3'

11. DISCUSSION

A . Equilibrium Constant Measurements

The hydrochlorination of SiC14 and m.g. SiHCl is an equilibrium reaction. The overall 3 written as,

3 SiClb + H2 Si 4

silicon to form reaction may be

SiKC13 (1)

The equilibrium constant, K, based on mole fraction of reactants and products, is defined in accordance with the stoichiometry of the hydrochlorination reaction (1).

K = J

(SiC14j3 (H2J2

1

i.;:. . : dF cCu:r \ - - * t = * J 41

. r ... . (

The a c t i v i t y (concentrat ion) o f elemental silicon 18 taken as unity. The equilibrium constant, partial pressure of r eac t an t s and products, is given by,

expressed i n terms of KP,

The p a r t i a l pressure i s obtained by multiplying the mole f r a c t i o n w i t h t h e t o t a l pressure, P. Thus,

The equilibrium constants were measured as a funct ion of temper- a tu re , concentration and pressure.

(1) Equilibrium Constant as a Function o f Temperature

A s e r i e s o f experiments on the hydrochlorination of SiC14 and m.g. s i l i c o n was ca r r i ed out a t 100 psig, H2/SiC14 feed r a t i o o f 2.0 and a t var ious reac t ion temperatures. S u f f i c i e n t l y long residence times were allowed f o r t he experiment s o t h a t the hydrochlorination r eac t ion was well within equilibrium. The reac t ion product composition was then measured by the in- l ine gas chromatograph (G.C. ) a t the reac t ion temperature of 500’C, 525’C, 5 5 O o C and 575’C, respect ively. Resul ts of the G.C. measure- ments a r e summarized i n Table I. The mole $ of S i H C l and o f SiC14 i n Table I was converted t o mole f r zc t ions . The concentration of hydrogen i n the reac t ion product mixture was not experimentally determined. However, i t can be ,*easily calculated. Since one mole of hydrogen is consumed f o r every two moles of SiHCl produced

and s ince one mole of hydrogen is consumed f o r every mole o f S i H 2 C 1 2 produced, the concentration of hydrogen at equilibrium i s given by,

3

3

- C HZ = a - ’ ‘SiHC13 S ~ H ~ C l2

2

where % The valugs of K and K data and from the p a r t i a l pressure data obtained a t equilibrium. Resul ts a r e summarized i n Table 11. As t h e r e s u l t s i n Table I1 show, t h e equi l ibr ium constants f o r t h e hydrochlor inat ion r eac t ion increase as a func t ion of increas ing reLCtion temper- ature .

i s the i n i t i a l hydrogen concentrat ion i n t h e feed. were ca l cu la t ed from t h e mole f r a c t i o n P

( 2 ) Heat of Reaction, A H

The heat o f reac t ion ,AH, is ca lcu la ted by t h e Second Law Method. S t a r t i n g from t h e equation,

A F = -RT 1 n K

by d i f f e r e n t i a t i o n w i t h respec t t o T ,

- s d A F - - - dT

one obtains t h s well-known Van't

2 d l n K AH = RT d T

Hoff equation,

where,AF is the Free Energy, R i s t h e i d e a l gas constant , T i s the temperature and S i s the Entropy. By s u b s t i t u t i n g dT = - T d ( l / T ) , one obtains , 2

Yhus, the slope o f a In K versus ( 1 / T ) p l o t is -.II\H/R. The logarithm of t he equilibrium constant K i n Table I1 i s then p lo t ted aga ins t the inversed temperature, 1/T. R e s u l t s a r e given i n Figure I. The p l o t i n f i g u r e I g ives a s t r a i g h t l i n e . 'The heat of reac t ion , A H , is then determined from the s lope

3

o f t he s t r a i g h t l i n e t o give a value of 10.6 Kcal/mole f o r t h e hydrochlorination reac t ion . Thus, the hydrochlor inat ion of SiC14 and m a g . s i l i c o n t o SiHCl is a s l i g h t l y endothermic reac t ion . 3

( 3 ) EQuilibrium Constant as a Function of Concentration

A set of experimental data previously obtained from t h e hydrochlorination o f SiC14 experiments a t 100 ps ig , 500'C and a t var ious H2/S iC14 feed r a t i o s ( s e e Figure V, fou r th Q i a r t e r l y Report, Apr i l 9 t o J u l y 8, 1982) was analyzed. These experimental data are reproduced i n Figure X I . The equi l ibr ium S i H C l con- vers ions a t var ious H2/SiC1,, feed r a t i o s were d i r e c t l y measured f rom the p l o t s a t t h e point where the k i n e t i c curves l e v e l o f f . The mole % data were converted t o mole f r a c t i o n s as shown i n Table 111. The equi l ibr ium constar.ts, K and K were ca l cu la t ed i n the same manner as described i n Sect ion A (1). Resul ts a r e summarized i n t h e last two columns i n Table 111. The equi l ibr ium constants i n Table I11 remain e s s e n t i a l l y constant within experi- mental e r r o r a t the var ious H2/SiC14 feed r a t i o s ranging f rom 1 . 0 t o 4.7. The standard devia t ions f rom t h i s s e t of equi l ibr ium constant values are w e l l wi th in 2 10%. Thus, t h e equi l ibr ium constant f o r t he hydrochlor inat ion r eac t ion is constant w i t h respec t t o concentration. T h i s observation i s i n agreement with the t h e o r e t c i a l considerat ion.

3

P'

(4) Equilibrium Constant as a Function of Pressure

e expressed i n terms o f p a r t i a l pressures should a l s o be a consta,,c value w i t h respec t t o pressure A c o l l e c t i o n of equilibrium data previously obtained from the hydrochlorination of SiC14 and m.g. s i l i c o n a t 500°C and a t var ious pressures (from 25 ps ig t o 500 ps ig) and H2/SiC14 feed ra t ios (from 1.0 t o 4.7) i s summarized i n Table I V . The equi l ibr ium moles of SiHCl was obtained d i r e c t l y from t h e var ious k i n e t i c curves 3 a t the point where the '% SiHCl 3 residence times. These k i n e t i c curves have been published i n

KP The equilibrium constant ,

conversion leve led o f f at long

4

ORIGINAL PACE IS OF POOR QUALITY

previous Quar t e r ly Reports and i n t h e work carried out a t t h e Massachusetts I n s t i t u t e of Technology''). The mole % data were converted t o mole f r a c t i o n s and partial pressures. The va lues of K and K were then ca lcu la ted and l i s t ed i n the last two columns i n Table I V . Results i n Table I V show t h a t the e f f e c t of pressure on the equilibrium constant K i s r a t h e r complex, A t t he lower pressure range of 25 ps ig t o 100 psig, t he value of K remains constant a t about 0,65 x atm. . However, a t the higher pressure range of 150 ps ig t o 500 psig, t he value of K increases by a f a c t o r of two o r more, e.g., 1.3 x atmOF1 a t 500 psig. The reason f o r t he increase of the value of K a t the higher pressure range is not f u l l y understood a t the present time. Nevertheless, the v a r i a t i o n of K w i th respect t o pressure is reproducible by similar experiments on the hydrochlorination reac t ion a t a lower temperature. Table V summarizes t h e resul ts of the equilibrium constant measurements at 4 5 O o C and a t the similar ranges of pressures and H Z / S i C l 4 feed r a t i o . A t the lower pressure range of 25 ps ig t o 100 psig, the value of K about 0.35 x 10-3 a t m . of 150 psig t o 500 psig, the values o f K increase t o a much higher number, e .g . , 0.66 i- a t m . a t 500 psig.

P

P -1

P

P P

remains constant wi th in experimental e r r o r a t . Again, a t the higher pressure range P -1

-1 p

B. Rate Constant Measurements

The experimental r a t e data obtained from the hydrochlo- r i n a t i o n o f SiCl4 and m.g. s i l i c o n was found t o obey the psuedo-first order k ine t ics . The psuedo-f i rs t order r a t e equation f o r the hydrochlorination r eac t ion was described i n the last Quar t e r ly Report.

kl

k- 1 SiC1& . b SiKCl3

'e v- - k l a xe In xe - x

5

3 where x is the concentration (or partial pressure) of SiHCl at time t, xe is the concentration of SiHCl a is the initial concentration of SiClq in the feed, A p l ~ ~ the logarithm the experimental rate data obey the psuedo-first order kinetics. The rate constant, kl, is then determined from the slope of thr! straight line, which equals to ki a/xe.

at equilibrium and 3 L~

of xe/xe - x versus time t gives a J-traig. i. if

(1) Rate Constant as a Function of Temperature

The effect of temperature on the psuedo-first order rate constant, ki, was reported in the last Quarterly Report. The variation of kl with respect to reaction temperature provided a measurement on the ,ctivation energy,AE, for the hydrochlo- rination reaction by plotting the logarithm of kl versus the inversed temperature, l/T, in the Arrhenius equation. The value of A E was found to be 13.2 Kcal/mole. The effect of concentration (H2/SiC14 feed ratio) and pressure on the reaction rate was studied this quarter,

(2) Rate Constant as a Function of Concentration

A set of rate data obtained from the hydrochlorination of SiC14 and m.g. silicon at 100 psig, 500°C and c t vmious H2/SiClk feed. ratios (1.0 to 4.7) was analyzed by the psuedo-first order kinetics. These experimental data are shown by -he kinetic curves in Figure 11. The SiHCl conversions at various residence times of 10, 20, 30, 40 and 60 seconds were directly measured from these kinetic curves. The mole % conversion data were converted to mole frations and partial pressures as summarized in Table VI, Table VII, Tab12 VI11 arid Table IX for the experiments with the H2/SiC14 feed ratio of 4.7, 4,0, 2.8, 2.0 and 1.0, respectively. The equilibrium composition of SiHC13, xe, was taken at the point where the kinetic curves leveled off. The initial partial pressure of SiC14, a, was calculated from the composition of the H2/SiClI, feed. The logarithm xe/xe-x was calculated from the partial pressure data and pltrted against the reaction time t as shown

3

6

in Figure 111, Figure IV, Figure V , Figure VI and Figure VI1 f o r t h e experiments wi th the H2/SiC1,, feed r a t i o of 4.7, 4.0, 2.8, 2 .0 and 1.0, respec t ive ly . Resul t s i n thesa Figures show t h a t a straight l i n e was obtained i n each of t h e p lo t . The rate constant , kl, was ca lcu la ted from the s lope of t h e s t r a i g h t l i n e , which equaled t o kia/xe. Results a r e summarized i n Table XI. Data i n Table XI show t h a t the rate constant s l i g h t l y increases a t a h igher H 2 / S i C 1 4 feed ratio. These r e s u l t s suggest ' that t h e hydrochlor inat ion of S1C14 and m . g . s i l i c o n t o SiHCl proceeds a t a s l i g h t l y faster r a t e a t a higher concentration of hydrogen gas.

3

( 3 ) Rate Constant as a Function o f Pressure

A similar t h e o r e t i c a l treatment o f the r eac t ion k i n e t i c data obtained f r o m the hydrochlor inat ion o f SiC14 and m.g. s i l i c o n a t var ious pressures was performed. A s e t of k i n e t i c curves obtained a t 500°C and w i t h a H2/SiC14 feed r a t i o of 2.0 a t var ious pressures of 25 psig, 100 ps ig and 200 p s i g i s reproduced i n Figure VIII. The ra te of S i H C l formation 3 mole% conversion) was d i r e c t l y read from these smcoth I r i , _ i c curves a t 10, 20, 30, 4r) and 60 seconds residence time. Tne mole $ data were converted t o mole f r a c t i o n s and par t ia l pressures f o r H2, SiHCl Table X I 1 1 and Table XIV f o r t h e corresponding experiments a t 25 psig, 100 ps ig and 200 ps ig , respec t ive ly . The equilibrium conversion o f S i H C l xe, was neasured a t the point where the k i n e t i c curves leveled of f a t loRg residence times. The i n i t i a l SiC14 pa r t i a l pressure, a, was ca lcu la ted from the H 2 / S i C 1 4 feed r a t i o and the r eac to r pressure. The loga r i thm of xe/xe-x was ca lcu la ted and p lo t t ed aga ins t the r eac t ion time t as shown i n Figure I X , F igwe X and Figure XI f o r t he corresponding experiments at 25 psig, 100 psig and 200 ps ig respes t ive ly . A s t r a i g h t l i n e was obtained from each o f t he p lo t i n these Figures. The r a t e constant , kl, was ca lcu la ted from the slope

and SiC14 and summarized i n Table XII, 3

3'

of the straight l i n e , which equaled t o kla/xe. Results of t h e r a t e constant measurements a r e summarized i n TableXV. Two more data poin ts on the r a t e constant at 73 peig and a t 500 ps ig were obtained by the same reac t ion k ine t i c treatment. These experi- mental r a t e data were obtained a t a s l i g h t l y higher H2/SiC14 feed r a t i o (2.8 ins tead of' 2 . 0 ) . The r a t e constants measured a t 73 psig and a t 500 psig a r e a l s o summarized i n Table XV. Results i n TableXVshow t h a t the psuedo-first order r a t e constant, kl, gradual ly decreases as a funct ion of increas ing pressure. The r a t e constants i n TahleXVwere p lo t t ed againwt the pressure ( i n atmospheres) as shown i n Figure XII. The graph i n Figure XI1 shows t h a t the e f f e c t of pressure on t 5 e hydrochlorination reactioiz r a t e ( r a t e constant) is not l i n e a r . An attempt i s i n progress t o incorporate the pressure e f f e c t i n t o the rat2 equation. The ul t imate goal is t o develop a generalized r a t e equation applicable t o the e n t i r e range of r eac t ion condi.tlons s tud iea t n c s far.

C . Reaction MechaniEm Study

Previous experimental studies") on the hydrochlorination o f SiC14 and m a g . s i l i c o n mechanism may involve two

SiC14 + H2

3 H C 1 + S i

showed t h a t a p laus ib le reac t ion stepwise reac t ions ,

s l o w S i H C 1 3 + H C 1

fast +' S i H C 1 3 + H2

The hydrogenation o f a Si-C1 bond by hydrogen t o f o rm S i H C l H C l was postulated as the s l o w , rate-determining s tep. By replacing hydrogen w i t h deuterium i n the hydrochlorination r e a c t i m , a posit?ve k ine t i c isotope e f f ec t may provide use fu l informations on the nature o f the ac t iva t ed complex and on the mechanism of t h e reac t ion pathway.

and 3

(1) The Quartz Hydrochlorination Reactor

Construction of t h e quar tz hydrochlorination r eac to r system was completed. T h i s quartz r eac to r was designed for the deuterium k i n e t i c isotope e f f e c t s study. The apparatus is schematically shown i n Figure X I I I . The design and operation of t h i s quartz r eac to r system were d ~ s c r i b e d i n detail i n t h e l a s t Quar t e r ly Report. Instruments and flowmeters were ca l ibra ted and standardized. The r eac to r system was successfu l ly started up. Hydrogen as used i n t h e i n i t i a l runs t o check out the system. These i n i t i a l experiments a l s o served t o "ciean" and t o s t a b i l i z e the f r e sh s i l i c o n metal mass bed by consuming some s i l i c o n i n the process. A s e r i e s of experiments on the hydrochlorination of SiClll and m.g . s i l i c o n w i t h tydrogcn and deuterium is planned. The r e l a t i v e r eac t ion r a t e s o-tween hydrogen and deuterium w i l l be studied as a funct ion of t e m - perature and H2/SiC14 o r D,/SiClb feed ratios. More experimental work is i n progress.

D. Summary of Progress

Experimental work on t h e JPL Contract No. 956061 has progressed i n accordance wi th the Program Plan. Theoret ical treatment of experimental r a t e data on the hydrochlorination react ion was car r ied ou t f o r the development of a r a t e equation and f o r the determination o f thermodynamic functions. Equilibrium constants f o r the hydrochlorination of SiC14 and m.g. s i l i c o n t o S i H C l were measured as a funct ion o f reac t ion temperatura, pressure and concentration. The heat of react ion, AH, was determined from the change o f the equilibrium constant as a function of temperature. The r a t e da ta obtained from the hydrochlorination =act ion was found t o obey the psuedo-first o r d e r k ine t i c s , The r a t e constants f o r t he psuedo-f i rs t order rate equation were measured as a funct ion of temperature, pressure and concentration. Variation of the r a t e constants as a function o f temperature provided a measurement on the

3

9

activation energy, AED for the hydrochlorination reaction. More work is in progress in an attempt to develop a generalized rate equation for the hydrochlorination of SiClq as2 m.g. silicon to include the entire range of reaction conditions studied so far. Construction cf the quartz hydrochlorination reactor system has been completed. This quartz reactor was successfully started up. Experiments on the deuterium kinetic isotope effects are in progress.

111. PROJECTED SEVENTH QUARTER ACTIVITIES

Planned activities for the seventh quarter (January - March) include

0 complete the experiments on the deuterium kinetic isotope effects study,

complete the theoretical treatment of the reaction kinetic data obtained from the hydrochlorination reaction,

0 complete the reaction mechanism study on the hydro- chlorination of SiC14 and m.g. silicon,

0 Final Report.

IV . REFERENCES

(1) Final Report, JPL Contract No. 955382, "Investigation of the Hydrogenation of SiC14" by Jeffrey Y. P. Mui and Dietmar Seyferth, Massachusetts Institute of Technology, April 15, 1981.

V. APPENDIX

Program P l a n SC-1

Table I to XV

Figure I to XI11

10

9

m m

c y -

d

I P I 01

H n n I R I,

I

: I s

I 0

ri & e 9 h u a

a u c n

I u 4 c

u u rl

&

4 0 tn

- 2 e e a

Q t

TABLE I

BQUILIBRIUM COYPOSITIONS OF CHLOROSILANE PRODUCTS FOR THE HYDROCHLORINATION OF SiCl,, AND M a c . SILICON NETAL AT 100 PSIG, HZ/SiC14 = 2.0 AND AT VARIOUS TEQdPERATURES

Sample Reaction Residence ‘remperatr: e Time

NO

I I I I

I1 I1 I1 I1

I11 I11 I11 I11

Iv Iv I’V

IV

‘C Second ~

lib8 148 148 140

Average =

138 138 138 138

Average =

101 101 101 101

Average =

98 98 98 98

Average =

Product Composition, Mole #

SiH2C12 SiHC13 SiCl,+

0.3326 0 8 3596 0.3779 0.3600

0 . 3675 0.4781 0.3651 0.4141 0 4359 0 4233

0.5730 0.5125 0 5099 0,5650

0 . 5406

0 5857 0 . 5294 0 . 5070 0.4828

0.5262

22 . 29

22.15 22. ii

22.13

21.98

23 25 22.98 22 92 22.93 23.02

24.05 23.99 24.21 23 98 24.06

24.89

24.85 24.92

24.88

2’4 84

~~ ~

77 33 77 66 77 47 77 53 77 30

76.27 76 . 66 76 . 66 76.64

76.56

75.38 75.51 35 28 75.45 75.40

74.53 74.63 74.64 74.60

74.60

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TABLE X I RATE CONSTANTS FOR THE HYDROCHLORINATION OF SiCl4 AT 100 PSIG, 5OO'C AS A FUNCTION OF HZ/SiC14 FEED RATIO

H2/SiC14 Equilibrium Composition Rate Constant Feed Mole $ kl Ratio SiHCl? sic14 x 10-3 Sec. -1

4. 7 28.0 72.0 12.7

4.0 26.8 73 .2 12.2

2.8 24.5 75.5 11.4

2.0 22.8 77.2 10.9

1.0 18.8 81.2 9.30

I

0

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X

1 5 I ?

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m rr

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drl I

rn 4 u X *rl VI

a0

b CD

cy

cy .1

H H X

w 4 E

d al U

r(

0 Y l-1 0

dtDX 0

X

4 = 5 u

@Ix I2 c r4

rl c) *l-i rn

X"

0, . 0

3 m L a 8 0 cv

TABLE XV SUMMARY OF RATE CONSTANTS FOR THE HYDROCHLORINA?I3N OF SiC14 AT 500.C AS A FUNSTION OF REACTOR PRESSUS-

Reactor Hz/SiC14 Pressure Ratio

psig. A t m .

25 2.70 2.0

73 5.97 2.8

100 7.80 2.0

200 14.6 2.0

500 35.0 2.8

Equilibrium Re .s Constant Mole % kl

SiCl4 1 0 - 3 ~ ~ ~ . -1 SiHCl

10.4 81.6 14.5

23.4 76.6 13.0

22.9 77.1 12.2

31.0 69.0 8.33

37.5 62.5 7.06

'3RlGlNkL PAGE Is CF POOR QUALITY

-4,6

- 4 8 7

-4 #8

- 4 8 9

-5.0

-5.1 SL

z A -5.2

-5.3

-5.4

-5.5

I 1.15

FIGURE - I PLOT OF THE VAN'T HOFF EQUATION LN K VERSUS INVERSED TEMPERATURE, A / T

- AH R

O H

I #

A F = -RTM

= Slope - - -4.890 + 5.425

(1.20-1.30) x

= -5.35 x 10 3

= 10.6 Kcal/mole

I I ' I '- 1.20 1,25 1.30

d s n I-

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v) ;rO A -

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w w

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n v)

+ N I

+ 3 A V

v)

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w

0 ln cu

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VI 0

OR(GIN,L P:\zL OF POOR QUALITY

FIGURE I11 PLOT OF THE PSUEDO=FIRST ORDER RATE EQUATION FOR THE HYDROCHLORINATION OF SIC14 AT - 100 B I G , 500 O C AND HZ/SICl4 RATIO 4 .7

kla t 'e xe - x In

a = 20.12 psia

x = 6.139 psia e

/ 0,0416 kl

xe Slope

= 12.7 10%~:~ kl

I 1 I 1 I I m I

0 10 20 30 40 50 60 70 80

Reaction Time, t Second

X"

4.0

3 . 0

2.0

X I

X"

r: d

1.0

0

FIGURE IV PLOT OF THE PSUEDO-FIRST ORDER RATE EQUATION FOR THE HYDROCHLORINATION OF SiC14 AT - 100 PSIG, 500 O C AND H,/SIC14 RATIO 4.0

xe. - - k l a xe xe - x In

a = 22.94 psia

x = 6.683 psia e

= 0.0418 kl a xe

Slope =

0 10 20 30 40 30 60 70 80

Reaction Time, t Second

FIGURE V

E: rl

1.0

0

PLOT OF THE ?SUEDO-FIRST ORDER RATE EQUATION FOR THE HYDROCHLORINATION OF SiCllc AT 100 PSIG, 500 'C AND H2/SiC14 RATIO 2.8

k. a

= 0.0428 kl a e X Slope =

k, = 11.4 x 10-3se~? I

- r- I I I I I

0 10 20 30 40 50 60 70 80

Reaction Time, t , Second

4.0 *

.

2.0

c rl

1.0

0

FIGURE V I PLOT OF THE PSUEDO-FIRST ORDER RATE EQUATION FOR THE HYDROCHLORINATION OF SiC14 AT - 100 PSIG, 500 *C AND H2/SiC14 RATIO 2 . 0

xe - - k l a x e xe - x In

= 0.0442 kl a xe

Slope =

= 10.9 1 0 - 3 , ~ ~ ~ ~ kl

0 10 20 30 40 50 60 70 80

Reaction Time, t Second

@ X

4.0

3.0

2.0

X I

*@ G d

1.0

0

FIGURE VI1 PLOT OF THE PSUEDO-FIRST ORDER RATE EQUATION FOR THE HYDROCHLORINATION OF SiC14 AT 100 PSIG, 500 O C AND H2,/SiS14 RATIO 1.0

xe - - kl a t xe - x In

/ a = 57.35 psia

x - = .11.60 psia

Slope = = 0.0460 k1 a xe

kl = 9.30 x lO'3sec?

0 10 20 30 40 50 60 70 80

Reaction Time, t Second

4 0 0

Y U

U > w Qs

c3 L L U

W c3 W v) v) v)

Y Y U

e e e

t3 v) e 0

Y

2

c3

v, e In cv

Y

0 0 In d 0 N cv 4

M J u =

II

U

v )

+ N I m +

b

3 0 0 M

- 0

0

0

3 V

v)

M

U

.O U. 4

52 0 0 w v,

'0 In

0

0

01 x

6.

5 .

4.

x I

xW3. d rl

2.

1.

0

FIGURE IX PLOT OF THE PSUEDO-FIRST ORDER RATE EQUATION FOR THE HYDROCHLORINAT'?N OF SiC14 AT 25 P X G 500 'C AND H2/SiC14 FEED RATIO OF 2.0

k t a t X - - e X e xe - x In

a = 13.23 ps i a

= 2.594 p s i a 'e

Slope = = 0.07ic-0 xe

kl = 14.5 x 10'3sec,i

0 10 20 30 40 60

iieaction Time t Second

a: x

4.0

3.0

2.0

x I

Q, x

E; rl

1.0

0

FIGURE X PLOT OF THE PSUEDO-FIRST ORDER RATE EQUATION FOR THE HYDROCFLORINATION OF SiCllc AT 100 PSIG, 500 O C AND H2/SIC1b RATIU 2.0

e e

a = 38.23 psia

x = 9.479 psia e

Slope = ki a = G.0492 xe

J 10 20 30 40 50 60 70 80

Reactjon Time, t , Second

X

FIGURE X I

x a l l

xu

PLOT OF THE PSUEDO-FIRST ORDER RATE EQUATION FOR THE HYDROCHLORINATION OF SiC1,+ AT

200 PSIG, 500 OC AND H2/SiClk RATIO 2.9

= 0.0241 kl a X Slope =

e

kl = 8 . 3 3 x 10-3sec,1

0 20 40 60 80 100 120 140 160

Reaction T i m e , t , Second

4 Y

L

0

ZT

0

-0

. r

. 0

O M

D -

W w I Q, v)

I-

o z N -

w 3 v) v) w pc: e

a

c ro -0 < -

a

w I- s

U

L I

L 0

I 1 ' I 1

0 In A

0

0 0 4

-

0 0 d

-

1