beneficial effects of cobalt addition to ni-catalysts for oxidative conversion of methane to syngas

8/10/2019 Beneficial Effects of Cobalt Addition to Ni-catalysts for Oxidative Conversion of Methane to Syngas

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: . \ ; : . : ( 5

E L S E V I E R

Applied Catalysis A: General 162 (1997) 235-238

~ PPLED

C T LYSS

A : G E N E R A L

B e n e f i c i a l e f f e c t s o f c o b a l t a d d i ti o n to N i c a t a l y s t s f o r

o x i d a t i v e c o n v e r s i o n o f m e t h a n e t o s y n g a s

V . R . C h o u d h a r y * , V . H . R a n e , A . M . R a j p u t

C h e m i c a l E n g i n e e r i n g D i v i s i o n N a t i o n a l C h e m i c a l L a b o r a to r y P u n e - 4 1 1 0 0 8 I n d i a

Received 9 July 1996; received in revised form 25 February 1997; accepted 26 February 1997

A b s t r a c t

Addition of cobalt to NiO/Yb203, NiO/ZrO2 and NiO/ThO2 catalysts causes a drastic reduction in the rate of carbon

formation and also results in a large decrease in the reaction start or the catalyst activation) temperature in the oxidative

conversion of methan e to syngas. ,~f: 1997 Elsevier S cience B .V.

Keywords

Methane-to-syngas convers ion; CoO-NiO-Yb203; CoO-NiO-ZrO2; CoO-NiO-ThO2; Oxidat ive convers ion of

methane

1 I n t r o d u c t i o n

N i c k e l c a t a l y s t s h a v e h i g h a c t i v i ty a n d s e l e c t iv i t y i n

t h e r e f o r m i n g o f h y d r o c a r b o n s t o s y n g a s i .e . CO a n d

H 2 ) a n d a l s o h a v e l o w c o s t [ 1 - 3 ] . H e n c e , t h e s e c a t a -

l y s t s a r e c o mmo n l y u s e d i n t h e s y n g a s p r o d u c t i o n

p r o c e s s e s . T h e s e c a t a l y s t s a r e , h o w e v e r , a l s o k n o w n

f o r w h i s k a r t y p e c a r b o n d e p o s i t i o n o n t h e m i n t h e

h y d r o c a r b o n r e f o r mi n g p r o c e s s e s , c r e a t i n g t e c h n i c a l

p r o b l e ms [ 1 ,2 ]. T h e c o k e d e p o s i t i o n o n n i c k e l i s mu c h

fas t e r than tha t on nob le meta l s [4 ] . In our ear l i e r

s t u d i e s [ 5 , 6 ] , N i O / Y b 2 0 3 c a t a l y s t s h o w e d h i g h

a c t i v i t y a n d s e l e c t i v i t y b u t s h o w e d f a s t c a r b o n

f o r ma t i o n i n t h e o x i d a t i v e c o n v e r s i o n o f me t h a n e

t o s y n g a s a t e x t r e me l y l o w c o n t a c t t i me . O u r

p r e l i m i n a r y s t u d i e s o n t h i s r e a c t i o n o v e r N i O / Z r O 2

a n d N i O / T h O 2 c a t a l y s t s a ls o i n d i c a te d t h a t t h e s e t w o

*Corresponding author.

0926-860X/97/ 17.00 ,~ 1997 Elsevier Science B.V. All rights reserved.

P I I

S0926 -860X (97) 00 1 0 1 -4

c a t a l y s t s a r e h i g h l y a c t i v e a n d s e l e c t i v e b u t c a r b o n

d e p o s i t i o n o n t h e m i s v e r y f a s t . I n t h i s c o mmu n i c a -

t ion , we sh ow tha t , becau se o f the add i t ion o f coba l t t o

N i O / Y b 2 0 3 , N i O / Z r O 2 a n d N i O / T h O 2 c a t a l y s t s , t h e

ra t e o f carbon depos i t ion on these ca t a lys t s in the

o x i d a t i v e c o n v e r s i o n o f me t h a n e t o s y n g a s i s d r a s t i -

c a l l y r e d u c e d a n d a l s o t h e r e a c t i o n o v e r t h e s e c a t a l y s ts

s t a r ts i .e . the ca t a lys t i s ac t iva ted ) a t l owe r t emp era-

ture.

2 E x p e r i m e n t a l

T h e N i O / Y b 2 0 3 , N i O / C o O / Y b 2 0 3 , N i O / Z r O 2 ,

N i O / C o O / Z r O 2 , N i O / T h O 2 a n d N i O / C o O / T h O 2 c a t a -

l y s ts T a b l e 1) w e r e p r e p a r e d b y t h o r o u g h l y mi x i n g

f ine ly g round n icke l n i t ra t e wi th o r wi thou t coba l t

n i t ra t e and Yb203 Aldr i ch ) , z i rcony l n i t ra t e o r tho r -

i u m n i t r a t e i n r e q u i r e d p r o p o r t i o n s w i t h d e i o n i z e d

w a t e r t o f o r m a t h i c k p a s t e , d r y i n g a n d d e c o mp o s i n g


2/4

V .R . C h o u d h a r y e t a l . / A p p l i e d C a t a l y s i s A : G e n e r a l 1 6 2 1 9 9 7 ) 2 3 5 - 2 3 8

o

> N i O / Z r O 2 > N i O / Y b 2 0 3 . H o w e v e r , t h e a d d i -

t ion o f coba l t t o these ca ta lys t s resu l t s in a d ras t i c

r e d u c t i o n i n t h e c a r b o n f o r ma t i o n , t h u s i n c r e a s i n g

the i r s t ab i l i ty and a l so causes a l a rge decrease in the i r

r e a c t i o n s t a r t t e mp e r a t u r e , m a k i n g t h e c a t a l y s t a c t iv a -

t ion eas ie r i .e . a t l ow er tem pera tu re) in the ca ta ly t i c

p rocess .


4/4

238

V . R. C h o u d h a ~ e t a l . / A p p l i e d C a t a l y si s A : G e n e r a l 1 62 1 9 9 7 ) 2 3 5 - 2 3 8

cknowledgements

V . H . R a n e i s g r a t e f u l t o t h e C o u n c i l o f S c i e n t i f i c

a n d I n d u s t r i a l R e s e a r c h , N e w D e l h i , f o r t h e a w a r d o f a

P o o l O f f i c e r s h i p .

References

[2] S.C. Tsa ng, J.B. Claridge, M .L.H. G reen, Catal. Today 23

1995) 3.

[3] S.S . Bhardwaj, L.D. Schmidt , Fuel Process. Tech. 42 1995)

109.

[4] J .B. Claridge, M.L.H. Green , S.C. Tsang, A .P.E. York , A.T.

Ashcroft, P.D . Ba ttle, Catal. Lett. 22 1993) 299.

[5] V.R . Choudhary, V.H. Rane, A.M. Rajput , J . Phys. Chem. 96

1992) 8686.

[6] V.R. Choudhary, V.H . Rane, A .M. Rajput , Catal . L ett. 22

1993) 289.

[1] J.R. Rostrup-Nielsen, Catal. Today 18 1993) 305.

beneficial effects of cobalt addition to ni-catalysts for oxidative conversion of methane to syngas

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