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The activation of an adsorbent charcoal surface Brewer, Charles Patrick 1940

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THE ACTUATION OF AN ADSORBENT CHARCOAL SURFACE by C h a r l e s P. Brewer Under the D i r e c t i o n o f Dr. M. J . M a r s h a l l A T h e s i s s u b m i t t e d i n , p a r t Requirement f o r the Degree o f MASTER OF ARTS /. _ i n the Department o f CHEMISTRY THE UNIVERSITY OF BRITISH COLUMBIA A p r i l , 1940 CONTENTS Page I n t r o d u c t i o n 1 E x p e r i m e n t a l 7 Summary 15 B i b l i o g r a p h y 16 1 THE ACTIVATION OF AN ADSORBENT CHARCOAL SURFACE INTRODUCTION • I n a p r e v i o u s i n v e s t i g a t i o n c a r r i e d on at t h i s U n i v e r -s i t y ^ , a c h a r c o a l w i t h p e c u l i a r p r o p e r t i e s was d i s c o v e r e d . T h i s c h a r c o a l was found to reduce C 0 g t o CO, and the r e s u l t i n g gas c o u l d be pumped o f f the c h a r c o a l by r a i s i n g the temper-a t u r e . No known procedure o r process t o which the c h a r c o a l had been s u b j e c t e d c o u l d be o f f e r e d as an e x p l a n a t i o n of t h i s s t r a n g e a c t i o n , as the , r e s u l t s -were found to be non-reproduc-i b l e . T r i a l of s e v e r a l methods d i d not l e a d to a c o r r e c t ex-p l a n a t i o n or treatment f o r the p r o d u c t i o n of t h i s , 1 s u p e r - a c t -i v e " c h a r c o a l , a l t h o u g h the work o f - M i s s - F . Wright o f f e r e d a c l u e . I t was, t h e r e f o r e , the purpose o f t h i s i n v e s t i g a t i o n t o t r y (anqt determine a method or s e r i e s o f t r e a t m e n t s which would produce a " s u p e r - a c t i v e " c h a r c o a l — i . e . , i n t h i s case, a c h a r c o a l s u r f a c e .capable, as McMahon 1 found, o f r e d u c i n g C0 g t o CO. Befor e g i v i n g an account o f the e x p e r i m e n t a l p r o c e d u r e , i t would be w e l l , perhaps, t o pre s e n t and d i s c u s s some of the t h e o r i e s and methods of a c t i v a t i o n of c h a r c o a l . I t has been found by experiment t h a t the hydrocarbons and other f o r e i g n s u b s t a n c e s , which are pre s e n t on the s u r f a c e o f a c h a r c o a l formed by d e s t r u c t i v e d i s t i l l a t i o n at low temp-e r a t u r e s , " w i l l prevent the a d s o r p t i o n o f gases and vapors and ' w i l l hence i n a c t i v a t e the c h a r c o a l . T h e r e f o r e , i t i s neces-s a r y t o s u b j e c t the s u r f a c e t o some p r o c e s s , u s u a l l y o x i d a t i o n or d i s t i l l a t i o n j which w i l l remove . the f o r e i g n m a t e r i a l from, the c h a r c o a l and thus produce an a c t i v e adsorbent surface-. The most f a c i l e p rocess i s a c t i v a t i o n by a i r , which o x i d i z e s away any f o r e i g n m a t e r i a l , and a l s o some of the char-c o a l . Lamb, W i l s o n and Ghaney 3 gave 350°-450°G as the best 4 temperature ranges but McBain s t a t e s t h a t any temperature be-er o tween 350 -1150 C i s p e r m i s s i b l e , the best r e s u l t s b e i n g ob-5 t a i n e d hear the two l i m i t s . On the o t h e r hand, Burrage , from a c o n s i d e r a t i o n of t h e - s t r u c t u r e o f the b a s i c m a t e r i a l s " which make up the c h a r c o a l / p o i n t s out t h a t a i r a c t i v a t i o n w i l l g i v e r i s e t o a c h a r c o a l , poor a t low p r e s s u r e s and perhaps a l s o a t h i g h p r e s s u r e s . , 'Since a i r a c t i v a t i o n may be opera t e d at a low temper-a t u r e , i t w i l l thus have advantages i n , ' i t s f a v o r . " .Ho?^ever, the o x i d a t i o n o f hydroca r b o n s , and of amorphous carbon i s an exothermic p r o c e s s , and so l o c a l o v e r h e a t i n g w i t h a consequent consumption o f c h a r c o a l appears* A n o t h e r , and more e f f e c t i v e method of a c t i v a t i o n i s t h a t employing superheated steam as the a c t i v a t i n g agent. T h i s " i s used i n the commercial a c t i v a t i o n p r o c e s s . Steam at temper-a t u r e s from 800° t o 1000°Cis passed over the c h a r c o a l , and g i v e s a f a i r l y good adsorbent s u r f a c e . A l t h o u g h the r e g u l a t i o n o f steam a c t i v a t i o n i s r a t h e r d i f f i c u l t , s i n c e i t operates at h i g h t e m p e r a t u r e s , the r e a c t i o n between carbon and steam i s " 3 endothermic, and thus a s t a b l e s t a t e i s reached, as no l o c a l o v e r h e a t i n g appears. Controneo" 1" 0 however, i n h i s s t u d i e s of steam a c t i v a t i o n of v a r i o u s n u t - s h e l l s , found t h a t the l o s s i n weight o f the m a t e r i a l s i n c r e a s e d as temperature and time of a c t i v a t i o n were i n c r e a s e d , and that these two must not go beyond c e r t a i n l i m i t s or the a c t i v a t i o n f a i l e d . He a l s o n o t -i c e d t h a t an i n c r e a s e i n steam f l o w improved a c t i v a t i o n . Bur-5 rage a g a i n -points out t h a t steam, be i n g a m i l d e r o x i d i z i n g agent than a i r , would not a t t a c k the b a s i c m a t e r i a l s , c e l l u l o s e and l i g n i n ^ as d r a s t i c a l l y as a i r , and thus ?/ould g i v e r i s e t o a b e t t e r a c t i v e c h a r c o a l . Another process ' i n v o l v e s the use of carbon d i o x i d e and steam t o g e t h e r . Chemicals are sometimes used to prepare a c i v e c h a r c o a l , and among these z i n c c h l o r i d e i s perhaps the most i m p o r t a n t . The wood, or other s t a r t i n g m a t e r i a l , i s f i r s t t r e a t e d w i t h z i n c c h l o r i d e , which i s a s o l v e n t f o r c e l l u l o s e , arid i s then p r o c e s s e d by some oth e r a c t i v a t i o n method. However, the main f a u l t i n the use of c h e m i c a l s i s the d e p o s i t i o n of s l i g h t am-ounts o f i n o r g a n i c m a t e r i a l i n the pores of the c h a r c o a l — a m -ounts which cut the adsorbent power t o a low l e v e l . I n a l l these methods mentioned above, the e s s e n t i a l procedure has been the breakdown or c o n v e r s i o n of hydrocarbons of h i g h b o i l i n g p o i n t i n t o more v o l a t i l e p r o d u c t s , and the r e -moval of these p r o d u c t s . Hence i t i s r e a s o n a b l e t o suppose t h a t the a c t i v e c h a r c o a l i s u n d e r l y i n g s e v e r a l l a y e r s of hydro-carbons. I n c o n n e c t i o n w i t h t h i s , i t would be w e l l to examine the t h e o r y of Ghaney and h i s a s s o c i a t e s ' . T h i s t h e o r y s t a t e s t h a t elementary carbon c o n s i s t s of two f o r m s — - a c t i v e and i n a c t i v e or OC and ^ . A l l unact-i v a t e d c h a r c o a l c o n s i s t s of hydrocarbons adsorbed on a base of a c t i v e OC carbons. A c t i v e carbon i s supposed t o be formed whenever a compound i s decomposed belo\¥ 50G°-600° t o g i v e c a r -bon. An example i s : -200 — G 0 2 + C which proceeds a t 300°G. u s i n g FegOg as a c a t a l y s t , 6 and g i v e s a c h a r c o a l w i t h h i g h a d s o r p t i v e power. Hydrocarbons which de-compose above 700°C g i v e the i n a c t i v e c a r b o n - - l i k e g r a p h i t e . S i n c e amorphous a c t i v a t e d c h a r c o a l can be i n a c t i v a t e d by s p r e -a d i n g a t h i n f i l m o f g r a p h i t e over i t s s u r f a c e , i t i s reaso n -a b l e t o assume t h a t the a e t i v e carbon i s formed f i r s t i n des-t r u c t i v e d i s t i l l a t i o n , and then i t ^ adsorbs a q u a n t i t y of hydro-carbons i n such a way t h a t t hey are h e l d at temperatures above t h e i r b o i l i n g p o i n t s . T h e r e f o r e , the a c t i v a t i o n process must c o n s i s t i n removing these hydrocarbons from the a c t i v e carbon. 9 Leaker s u p p o r t s t h i s view, when he showed t h a t the d i f -f e r e n c e between c h a r c o a l and a c t i v e carbon was accounted f o r by the presence o f hydroca r b o n s , which he removed by e x t r a c t i n g h i s m a t e r i a l w i t h s e l e n i u m o x y c h l o r i d e i P r e v i o u s l y he found t h a t pure carbon and s e l e n i u m o x y c h l o r i d e do not r e a c t . H i s " e & t r a c t e d " carbon showed the same a c t i v e p r o p e r t i e s as a steam a c t i v a t e d . c h a r c o a l . T h e r e f o r e Ghaney concluded t h a t a c t i v e carbon was c a r -bon f r e e from a l l adsorbed h y d r o c a r b o n s , and a l s o f r e e from any carbon d e p o s i t e d by t h e , d e c o m p o s i t i o n of hydrocarbons. Briggs" 1- 1 o b j e c t s to Ghaney's t h e o r y on the grounds t h a t , the optimum temperature of a c t i v a t i o n advocated by 3 Chaney , i s not h i g h enough to remove the r e s i d u a l h y d r o c a r -bons. . He suggests t h a t any d i s r u p t i o n by h e a t i n g the s u r f a c e atoms I n carbon i s r e n d e r e d permanent i f some oxygen, from a i r or steam, i s p r e s e n t , but i n an i n e r t atmosphere t h i s does not take p l a c e * The d i s r u p t i o n of the s u r f a c e atoms l e a d s t o a c t i v a t i o n . 20 B a r k e r ' s work, t o o , o f f e r s another o b j e c t i o n t o Chaney's t h e o r y , f o r the former found t h a t a c t i v a t e d c h a r c o a l showed the d i f f r a c t i o n r i n g s ; o f g r a p h i t e , under exposure t o X - r a y s , w h i l e i n a c t i v e carbon d i d n o t . T h i s would l e s s e n the importance o f the adsorbed hydrocarbon t h e o r y as i t would seem t o show t h a t the a c t i v a t i o n was due t o a d i f f e r e n t s t a t e t a k e n up by the carbon atoms. ,, 12 13 14 Many c l a i m s ' ' ' have been made as to the best temperature f o r a c t i v a t i o n , and the r e s u l t s are. t h e r e f o r e apt t o be c o n f u s i n g . These d i f f e r e n c e s p r o b a b l y r e s u l t from de-f i n i t e d i f f e r e n c e s i n t e c h n i q u e and a p p a r a t u s , and i t i s t o be r e g r e t t e d t h a t the l a t t e r a r e not, s t a n d a r d i z e d or p u b l i s h e d . However, M i s s W r i g h t , working at t h i s u n i v e r s i t y , has e s t a b -l i s h e d . t h a t t h e r e d u c t i v e c a p a c i t y of a c h a r c o a l i s a d i r e c t and almost l i n e a r f u n c t i o n o f the time of h e a t i n g and out-g a s s i n g a t temperatures over 1100°C. T h i s i s i n d i r e c t con-16 17 t r a d i e t i o n t o the work of Lawry and Bemon who a p p a r e n t l y d i d not heat l o n g enough, as they note a d e a c t i v a t i o n on h e a t -i n g above 1000° f o r any c o n s i d e r a b l e l e n g t h o f time* 6 18 19 S e v e r a l experimenters ' ' have o f f e r e d e x p l a n a t i o n s • of a c t i v a t i o n of a c h a r c o a l s u r f a c e as caused by the removal 8 20 22 23 of adsorbed oxygen. Others ' ' ' ' have drawn a p a r a l -l e l between decrease i n hydrogen content and i n c r e a s e i n a c t -i v i t y . B r i e f l y , the former t h e o r y s t a t e s t h a t oxygen i s bound c h e m i c a l l y t o " p o i n t s " of d i f f e r e n t a d s o r p t i o n p o t e n t i a l , and t h a t on r a i s i n g the temperature, t h i s bound oxygen i s l i b e r -a t e d , l e a v i n g behind an u n s a t u r a t e d s u r f a c e f o r c e . The l a t t e r 24 25 t h e o r y , as s t a t e d by Lowry ' ' h o l d s t h a t the removal o f hydrogen from a G—H bond which cannot then o r i e n t i t s e l f i n t o a g r a p h i t e l a t t i c e , i s i n s t r u m e n t a l i n i n c r e a s i n g the s u r f a c e a c t i v i t y . I f , on the oth e r hand, so much hydrogen i s removed t h a t a g r a p h i t e l a t t i c e can be formed by the re m a i n i n g carbon atoms* d e a c t i v a t i o n t a k e s p l a c e , and t h i s i s the e x p l a n a t i o n o T f e r e d by Lowry f o r the apparent d e a c t i v a t i o n which he n o t i -o 1 ^  ced on h e a t i n g a c h a r c o a l over 1000 C. M i s s Wrights work has, however, o f f e r e d another and more l o g i c a l e x p l a n a t i o n o f t h i s e f f e c t . EXPERIMENTAL As s t a t e d b e f o r e , the aim of t h i s i n v e s t i g a t i o n was t o determine what treatment or treatme n t s are n e c e s s a r y t o produ ce a s u p e r - a c t i v e charaoal--one which w i l l reduce COg t o CO at room temperature. A r e p r o d u c i b l e p r o c e s s was sought f o r , as o t h e r w i s e i t s use would be c u r t a i l e d . The apparatus used 1 15 was the same as t h a t of McMahon and M i s s Wright i f o l l o w i n g McMahon'a"** work, the c h a r c o a l was f i r s t o u t -gassed, then t e s t e d w i t h G0 g f o r r e d u c t i v e power. Outgassing was c a r r i e d on f o r about 12 hours at 1000°G. The r e d u c t i v e c a p a c i t y of the c h a r c o a l was determined at 18.1 mieromoles/g. The c h a r c o a l was then outgassed f o r 22 hours at 1000°C and a s m a l l amount o f gas (.818mm/g) added. McMahon had found t h a t on r a i s i n g the temperature of t h e c h a r c o a l w h i l e gas was ad-so r b e d , the p r e s s u r e over the c h a r c o a l r o s e a l s o , and i f the temperature was r a i s e d , t h e n kept s t e a d y , the p r e s s u r e f i r s t r o s e , then f e l l o f f a b r u p t l y , and f i n a l l y more s l o w l y t o an e q u i l i b r i u m v a l u e . He n o t i c e d t h a t t h i s e f f e c t , w h i l e r e p r o -d u c i b l e f o r a s t e a d y r i s e i n temperature would not be r e p r o d -uced t w i c e i n the same temperature range. I t was de c i d e d t o i n v e s t i g a t e the p r e s e n t c h a r c o a l w i t h rega.rd t o t h i s phenom-enon, as i t was f e l t t h a t i t might o f f e r some measure o f a c t -i v a t i o n A c c o r d i n g l y j the temperature was r a i s e d by v a r i o u s s t e p s t o a c o n s t a n t v a l u e t w h i l e p r e s s u r e r e a d i n g s were taken 8 Graphs o f the form shown i n F i g . I were o b t a i n e d f o r a l l tem-p e r a t u r e s ranged from 62°-700°C» I n a l l c a s e s , the maximum pr e s s u r e reached i n the 2nd t r i a l was g r e a t e r than the e q u i l -i b r i u m p r e s s u r e reached i n the f i r s t , showing t h a t some gas had l e f t the s u r f a c e . However, i f the c h a r c o a l was s u b j e c t e d to a l o n g h e a t i n g at one temperature ( f o r s e v e r a l d a y s ) , the e f f e c t was no ' l o n g e r n o t i c e a b l e on a 2nd t r i a l . An e x p l a n a t i o n o f f e r e d f o r the phenomenon i s t h a t the gas l e a v e s the l e s s a c t i v e and adsorbs on the more a c t i v e s p a c e s , at each temperature. Hence, i t might be p o i n t e d out t h a t , i n a temperature range where a c t i v a t e d a d s o r p t i o n a l o n e i s supposed t o o c c u r , the d i f f e r e n c e between the maximum p r e s -s u r e on the 1 s t and 2nd t r i a l s r e p r e s e n t s the number of gas mo l e c u l e s adsorbed from the gas phase ( c a l c u l a t e d by pv ; nRT) and thus r e p r e s e n t s the number of " a c t i v e spaces" c r e a t e d by h e a t i n g at the known temperature f o r a known t i m e . T h i s i s t r u e , of c o u r s e , o n l y i f we assume u n i m o l e c u l a r a d s o r p t i o n . A f t e r t h i s p r o c e d u r e , the c h a r c o a l was outgassed f o r 22 hours at 1125°C, then was kept a t 25°C i n a t h e r m o s t a t -c o n t r o l l e d b a t h , and the r e d u c t i v e c a p a c i t y determined. The f o l l o w i n g t a b l e g i v e s a t y p i c a l r e s u l t f o r a d e t e r m i n a t i o n : -9 TABLE I Increment of G0 o T o t a l OOo T o t a l P r e s . P r e s . L i q -a i r On % G0 2 —•• —' UJ "' .9816 .9816 212 x 1 0 ~ 5 0 fo 1.291 2.372 33 x 1 0 ~ 4 1.018 3.390 51.X 1 0 ~ 4 — — _ . 1.082 4.472 -4 83 x 10 — 1,079 5,551 138.5 x 1 0 ~ 4 1,201 6.752 238 x. 1 0 ~ 4 1,374 8.126 -4 380 x 10 _ _ _ 1.391 9.517 565 x 1 0 " 4 1.367 10.884 1,44 11.324 2.371 13.69 328.5 x 1 0 " 4 1.475 15.17 470 x 1 0 ~ 4 1.43 16.60 529 x 1 0 * 4 507 x 1 0 ~ 4 4.13$ When the p r e s s u r e grew too g r e a t t o be read, on the.McLeod gua-ge, the guage was pumped down, then shut o f f w h i l e the gas was added t o the c h a r c o a l , and f i n a l l y opened when the char-c o a l was c l o s e d o f f a f t e r 10 m i n u t e s . The procedure f o l l o w e d i n making a t e s t was as f o l l o w s : A s m a l l a d d i t i o n o f gas was made and l e f t 10 minutes i n con-t a c t w i t h the c h a r c o a l . Then the c h a r c o a l was c l o s e d o f f and a d e t e r m i n a t i o n of the C 0 2 c o n t e n t o f the gas made. Ylhen the p r e s s u r e rose too h i g h t o be re a d i n the McLeod guage, the method o u t l i n e d i n the p r e c e d i n g paragraph was used. U n f o r t -10 u n a t e l y , the apparatus suddenly broke a f t e r the l a s t t e s t and exposed the c h a r c o a l t o the a i r f o r some time. A f t e r r e p a i r s were e f f e c t e d , the c h a r c o a l was outgassed a g a i n f o r 17 hours at 1000°C, and then a r e d u c t i o n t e s t a g a i n made. The r e d u c t -i v e power was found to have dropped to almost o n e - h a l f the p r e v i o u s v a l u e — i . e . , t o about 8.08 micromoles/g. As t h i s d i d not seem t o i n d i c a t e a f u r t h e r i n c r e a s e i n r e d u c t i v e power w i t h time of o u t g a s s i n g , i t was decid e d t o i n v e s t i g a t e another p o s s i b l e e x p l a n a t i o n f o r the a c t i v i t y . 26 D e v i l l e found t h a t on p a s s i n g CO through a r e d hot p o r c e l a i n tube, s u p p l i e d w i t h a s m a l l water condenser r u n n i n g through t h e m i d d l e , he,was ab l e t o d e p o s i t carbon on the con-denser tube, and to i d e n t i f y the i s s u i n g gas as C0g« I n an-o t h e r experiment, he passed pure CO over lampblack a t a temp-e r a t u r e " j u s t below the f u s i o n p o i n t o f s i l v e r " (960.5°C) and found the lampblack i n c r e a s e d i n we i g h t , w h i l e the i s s u i n g gas was a g a i n COg. 27 Woltereck a l s o worked on the therm a l d i s s o c i a t i o n o f CO, and found i t t o be i m p o s s i b l e even at h i g h temperatures, 28 when water was p r e s e n t . M. B e r t h e l o t i n v e s t i g a t e d t h i s de-c o m p o s i t i o n o f CO, and came t o the c o n c l u s i o n t h a t the de-p o s i t i o n o f carbon was due t o the decom p o s i t i o n of a complex of carbon and oxygen, g i v e n by the f o l l o w i n g e q u a t i o n : -10C0 > 2 C 4 0 S 2C0 2 2 G 4 ° 3 -*3C0 2 4" 5C 29 A, G a u t i e r d i s a g r e e s w i t h B e r t h e l o t ' s r e s u l t s , f o r he c a r r i e d 11 out a s e r i e s of experiments, and found no carbon was d e p o s i t e d . A c c o r d i n g t o aim-,-any carbon t h a t d i d appear was due to hy-drogen i m p u r i t i e s i n the 00 used. On the other hand* B e r t h e l -o t ' s experiments were c a r r i e d out w i t h much care* so h i s r e -s u l t s would seem t o be t r u s t w o r t h y . From the r e s u l t s g i v e n above, i t may be concluded t h a t GO w i l l decompose a t c e r t a i n temperatures t o g i v e GO and carbon. I t was t h e r e f o r e d e c i d e d t o t r y and c a r y out t h i s procedure i n the presence of the c h a r c o a l , as i t was thought the d e p o s i t e d carbon would be of h i g h a c t i v i t y . Another p o i n t t o be c o n s i d e r e d was the f o r m a t i o n o f T h i s gas, reduced by the c h a r c o a l s u r f a c e , would remove a carbon atom fr.om the s u r f a c e , and I n the f u r t h e r d e c o m p o s i t i o n of the carbon mon-oxide formed> t h i s carbon atom would a g a i n be d e p o s i t e d on the s u r f a c e , but most p r o b a b l y i n a d i f f e r e n t a r e a . T h i s constant rearrangement of the s u r f a c e carbon atoms might be an e x p l a n -a t i o n o f the a c t i v i t y o f the s u r f a c e . A c c o r d i n g l y , an optimum, temperature f o r the r e a c t i o n 2C0 — > GO -j- G 50 was sought, and was c a l c u l a t e d from f r e e energy data . The r e l a t i o n g i v i n g the f r e e energy change of the above r e a c t i o n was as f o l l o w s t -A F° = -40,910 +-4.9.T I n T - . 00495T 2-t-51 x 1 0 ~ 8 T 3 + 12.66 T and f o r temperatures o f 527° and 627°C, t h i s r e l a t i o n l e d t o v a l u e s o f the e q u i l i b r i u m c o n s t a n t o f 110 and 6.18 r e s p e c t -i v e l y , by making use of the e q u a t i o n : -12 - -RT I n K I t was d e c i d e d to t r y these two temperatures, p a r t i c -u l a r l y as they l i e i n the range where the decomposition of 28 GO was noted by B e r t h e l o t T h e r e f o r e the c h a r c o a l was heated t o 526°G and kept constant at t h a t temperature. The gas p r e v i o u s l y used i n the r e d u c t i o n t e s t was l e f t on the s u r f a c e , c o m p r i s i n g about 16 micromoles CO per gram. D u r i n g the r u n a t 526°C, the p r e s -sure and percentage of COg were noted at v a r i o u s i n t e r v a l s , a l t h o u g h the former was so h i g h the r e a d i n g s were taken w i t h a cathetometer. The r e s u l t s of the f i r s t r u n are shown below i n Table I I , i n which'the r a t e c o n s t a n t , k, i s c a l c u l a t e d f o r a 2nd ord e r r e a c t i o n , as most s u r f a c e r e a c t i o n s are of t h i s t y p e . TABLE I I Time ( h r s ) % of CO Converted _k 5 10.8 242.0 27 . 29.4 154 96 5. 5 6.15 148 10.0 7.5 155 16.4 12.65 172 13.9 9.4 192 13.9 8.4 319 11.46 4.06 341 13.9 4.74 I t i s obvious from the r e s u l t s shown t h a t the r e a c t i o n i s c e r t a i n l y not second o r d e r , k i s c a l c u l a t e d from the e q u a t i o n f o r a 2nd order r e a c t i o n k = 1 x c o t °o " x where C 0 " i n i t i a l c o n c e n t r a t i o n x Z amount changed i n time t I f the r e a c t i o n i s 2nd o r d e r , a s t r a i g h t l i n e s h o u l d be o b t a i -ned by p l o t t i n g x a g a i n s t t , and t h i s i s not the 0 o ( C o - x ) case. However, a change i n the percentage of COg was observed, and t h i s s h o u l d i n d i c a t e the need f o r f u r t h e r experiments, t o determine how l a r g e a change w i l l occur. The p r e s s u r e was a l s o observed t o drop, and t h i s i s i n l i n e w i t h what was ex-p e c t e d , as the r e a c t i o n 2 C 0 - — > C 0 2 + G i n d i c a t e s a p r e s s u r e drop. I n the 2nd r u n , a t 612°C, the f o l l o w i n g v a l u e s were ob-t a i n e d : -Time (hr s ) % CO changed x k -' ' " - C Q ( G 0 - X ) 1.5 17.6 251 x 1 0 ~ 4 167.5 74.5 19,6 288 x 1 0 ~ 4 3.87 141 20.8 311 x 1 0 ~ 4 2.24 where th e symbols have the same meanings as above. Here on p l o t t i n g x a g a i n s t , t , we do o b t a i n a very n e a r l y C 0 ( G 0 - x ) s t r a i g h t l i n e . T h i s would i n d i c a t e t h a t the r e a c t i o n a t 612°C i s almost 2nd order i n p a r t o f i t s course a t l e a s t . However, much more da t a i s n e c e s s a r y b e f o r e a d e f i n i t e statement can be 14 made. F o l l o w i n g these p r o c e d u r e s , another r e d u c t i o n t e s t was made a f t e r o u t g a s s i n g f o r 15 hours at 1090°G and i t was found t h a t the c h a r c o a l had not changed i n a c t i v i t y from the t e s t p r e v i o u s t o the above p r o c e s s — i . e . , i t s t i l l would reduce o n l y about 8 micromoles per gram. 15 SUMMARY I . I n v e s t i g a t i o n of the p r o p e r t i e s of the c h a r c o a l under c o n s i d e r a t i o n showed i t t o be l e s s a c t i v e than t h a t used by McMahon"1". As such, the p r e s s u r e - t i m e curves at one temp-e r a t u r e , were found t o be r e p r o d u c i b l e t o a c e r t a i n e x t e n t , and i t i s supposed that the r e v e r s i b i l i t y or i n v e r s i b i l i t y of these curves i s a measure of the a c t i v a t i o n of the c h a r c o a l . As f a r as was no t e d , h e a t i n g had no grea t e f f e c t on the a c t -i v i t y of the c h a r c o a l , e s p e c i a l l y a f t e r i t had been exposed f o r some time t o the a i r , f o l l o w i n g a break i n the apparatus. I I . The r e a c t i o n 2CQ >C02-\- G was i n v e s t i g a t e d w i t h r e g a r d to a new t h e o r y of a c t i v a t i o n . R e s u l t s o b t a i n e d were i n d i c a t i v e o f s u c c e s s , but more data must be o b t a i n e d . Only s m a l l amounts of CO were used i n the ru n s , and l a r g e r amounts might g i v e b e t t e r r e s u l t s . I t i s the i n t e n t i o n of the w r i t e r t o i n v e s t i g a t e t h i s p o s s i b i l i t y a t the e a r l i e s t p o s s i b l e t i m e . 16 BIBLIOGRAPHY I . McMahon, H. 0., T h e s i s , IT. B. 0., 1937* 3. Lamb, W i l s o n , Chaney, J o u r . Ind. Eng. Ghem. 11, 420, 1919 4. McBain, J o u r . Phys. Ghem., 34, 1439, 1939 5. Bu r r a g e , L. J . , Trans. Ear. Sac. , 29, 448, 1932. 6. Chaney, Trans. Am. Ele c t r o c h e r a . Soc. , 36, 91, 1919. 7. Chaney, Ray & S t . John, J o u r . I n d . Eng. Chem., 15, 1244, 1923. 8. Ray, Chem. Neb. Eng., 28, 977, 1923. 9. Lember, J . A. C. S., 44, 1644, 1922. 10. Gontroneo, Ghem. A b s t r a c t s , 9 5 6 0 8 , 1939. I I . B r i g g s , R. R. S. Lond. A.- C, 88, 1921. 12, H e r b s t , Biochem. Z., 115, 214, 1921. 13.. Howard & H u l e t t , S. Phys, Chem., 28, 1092, 1924. 14. D r i v e r & F i r t h , J o u r . Chem. S o c , 121, 2409, 1922. 15. M i s s F. Wr i g h t , T h e s i s , 17. B. C. , 1938. 16. Lowry & H u l e t t , J . A. G. S., 42, 1393, 1920. 17. Lemon, II. B. , Phys, Rev., 14, 281, 1919. 18. Allmand & P a t t i c k , P. R. Soc. Lond., A, 130, 197, 1930 19. Almand & C h a p l i n , P. R. Soc. Lond. A, 129, 235, 1930 20. B a r k e r , Ind. Eng. Chem., 22, 926, 1930, 22. P h i l i p & Jerman, J o u r . Phys. Chem., 28, 346, 1924. 23. Burgham & S t a f f o r d , J o u r . Chem, S o c , 117, 362, 1920 24. Lowry, H, H., J , A. C. S., 46, 824, 1924. 17 '••Bibliography cont'd 25. Lowry, H, K. • J o u r . Phys. Chem., 33, 1332, 1929. 26. D e v i l l e , H. S t . C l a i r e , Compt. Rend., 59, 873, 1864. 27. W o l t e r e c k , H. C., . Compt. Rend., 147, 460, 1909 28. B e r t h e l o t , M., Compt. Rend. , 112, 594. 29. G a u t i e r , A., Compt. Rend.,' 150, 1383. 30. Lewis & R a n d a l l * Thermodynamics. 

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