A study of the rates of carbon-carbon dioxide reaction in the temperature range 839 to 1050 C

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h e t e r o gH e n e o u s r e a c t i oE n of c a r b o n with c a r b o n T d i o x i d e g a s h a s b e e n the s u b j e c t of n u m e r o u s s t u d i e s o v e r the p a s t s i x d e c a d e s . Much of the i n t e r e s t in t h i s r e a c t i o n can be d i r e c t l y l i n k e d to the i m p o r t a n t r o l e it p l a y s in a n u m b e r of i n d u s t r i a l a p p l i c a t i o n s of c a r b o n . In a r e c e n t p u b l i c a t i o n , 1 one of t h e p r e s e n t a u t h o r s c o n f i r m e d the e a r l i e r view 1~ that the r a t e of the C-4202 r e a c t i o n , in effect d e t e r m i n e s the o v e r a l l k I n e t i c s of r e d u c t i o n of h e m a t i t e by c a r b o n . O t h e r i n s t a n c e s 2'a w h e r e i n the s a m e r e a c t i o n w a s n o t e d to e x e r c i s e c r i t i c a l influence on the o v e r a l l r a t e s a r e the g e n e r a t i o n of w a t e r g a s and the p r o d u c t i o n of p r o d u c e r g a s . T h i s p a p e r r e p o r t s on the r a t e s of t h e u n c a t a l y z e d r e a c t i o n b e t w e e n p o r o u s c a r b o n p e l l e t s and c a r b o n d i o x i d e g a s in t h e t e m p e r a t u r e r a n g e 839 ~ to 1050~ An a n a l y s i s of the influence of the m a s s t r a n s p o r t of CO2 (and CO) on t h e r e a c t i o n k i n e t i c s i s p r e s e n t e d . The w o r k p r e s e n t e d h e r e i n should b e v i e w e d in the c o n t e x t of a l a r g e r study d e v o t e d to the i n v e s t i g a t i o n of the c a t a l y t i c e f f e c t s of a l k a l i - m e t a l c o m p o u n d s on the C-CO2 r e a c t i o n . The r e s u l t s of the l a t t e r w o r k w i l l b e r e p o r t e d in a s u b s e q u e n t p a p e r . The i n t e r p r e t a t i o n of the r a t e d a t a on the g a s / c a r b o n r e a c t i o n s i s c o m p l i c a t e d by t h e fact that a p r e d o m i nant p a r t of the r e a c t i n g i n t e r f a c e m a y l i e within t h e p o r e s of the c a r b o n . A s i m p l i f i e d p i c t u r e of the s u c c e s s i v e s t e p s i n v o l v e d in t h e c a r b o n - c a r b o n d i o x i d e r e a c t i o n i s given h e r e . Y. K. RAO is Associate Professor, Henry Krumb School of Mines, Columbia University, New York, N . Y . B . P . JALAN, formerly Graduate Student, Henry Krumb School of Mines, Columbia University, is now Research Metallurgist, Gulf Chemical and Metallurgical Corp., Texas City, Texas. Manuscript submitted August 23, 197 I. METALLURGICAL TRANSACTIONS

1) T r a n s p o r t of CO2 to the e x t e r i o r s u r f a c e of the carbon pellet. 2) Diffusion of CO2 into t h e i n t e r i o r of the p o r o u s p e l l e t , v i z . , p o r e diffusion of r e a c t a n t . 3) C h e m i s o r p t i o n of CO2 on the p o r e s u r f a c e a s w e l l a s on the e x t e r n a l s u r f a c e . 4) S u r f a c e r e a c t i o n . 5) D e s o r p t i o n of CO, the p r o d u c t of r e a c t i o n . 6) O u t w a r d diffusion of CO f r o m the i n t e r i o r of t h e p e l