I. Introduction 447 II. Viewpoints on Chemical Mechanisms 448 III. The Mechanism 450 A. Adsorption Steps 450 1. Hydrogen Adsorption 450 2. Carbon Monoxide Adsorption 451 3. Carbon Monoxide Dissociation 451 B. Initial Reactions among Chemisorbed 454 Species 1. Reactions of C and O with H 455 2. Reactions of Undissociated CO 456 C. Reactions of Hydrocarbon and H-C-0 457 Intermediates D. Product Formation 460 1. Organic Products 460 2. Water 462 3. Carbon Dioxide 462 4. Unreactive Carbon 462 5. Metal Carbides and Oxides 463 IV. Comparison with Previously Proposed 463 Mechanisms A. Carbide Mechanism 464 B. Bureau of Mines Mechanism 464 C. Pichler-Schulz Mechanism 465 D. Mechanisms Based on Complex Chemistry 465 E. Ponec Mechanism 466 F. The Fischer-Tropsch Synthesis as a 466 Polymerization Reaction V. Extension to Other Systems 467 A. Carbon Monoxide Disproportionation 467 B. Water-Gas Shift Reaction 467 C. Methanation 468 D. Isosynthesis and Kolbel-Engelhardt 469 Synthesis E. Homogeneously Catalyzed Reactions

This report was prepared as an account of work sponsored by the United States Government. Neither the United States nor the United States Atomic Energy Commission, nor any of their employees, nor any of their contractors, subcontractor*, or their employees, makes any warranty, express or implied, or essumes any tegel liability or responsibility for the accuracy, completeness or usefulness of any information, apparatus, product or process disclosed, or represents that its use would not infringe privately owned rights. In the interest of prompt distribution, this LAMS report was not edited by the Technical Information staff.

INTRODUCTION The a b s o r p t i o n spectrum o f UF6 between 3400 and 4200 8, i s wellb u t t h e r e g i o n below 3400 ; h a s not been s t u d i e d i n any d e t a i l . 4200 A t h a t shows s i g n i f i c a n t s t r u c t u r e below 3400 A . The absorpt i o n i n t h i s r e g i o n must b e observed a t v e r y low p r e s s u r e s and r e l a t i v e l y s h o r t p a t h l e n g t h s . EXPERIMENTAL W e p r e s e n t h e r e a spectrum of UF6 between 2000 and 0 0 The a b s o r p t i o n c e l l was of s t a i n l e s s s t e e l , 5.5 cm long, and was c o n t a i n e d i n a c r y o s t a t of d e s i g n similar t o t h a t o f Ref. 4 . Sapphire windows were used on t h e c e l l , and q u a r t z windows on t h e c r y o s t a t j a c k e t . f l u o r i n e and subsequent o v e r n i g h t exposure t o UF6. The c e l l was c o n d i t i o n e d by o v e r n i g h t exposure t o The c e l l was f i l l e d w i t h 91.5 t o r r o f UF6, and t h e c r y o s t a t was cooled t o temperatures corresponding t o a p p r o p r i a t e vapor p r e s s u r e s f o r measuring t h e i n t e n s e a b s o r p t i o n . F i l l p r e s s u r e s of 65.1 and 5 2 1 Copyright 0 1975 hy Marcel Dekkcr. IncNcillicr this work n o r a n y p i r i may be reproduced or transmitted i i i a n y form or by any means. electronic or i~i e c l i a i~~c~i l , includiiip photocopying, microfilming. d i i d recording. or hy any infoi mation storage and retrieval systctn. without permission in writing from the publisher All Riphta Rescrvcd Downloaded by [University of Waterloo] at 03:45 15 December 2014 DE POORTER AND ROFER-DE POORTER 522 31.0 t o r r were a l s o used t o d e t e c t any p r e s s u r e e f f e c t s t h a t might r e s u l t from t h e design o f t h e c e l l . None were a p p a r e n t . Temperat u r e s ranged from 29G°K t o 228'K. The s p e c t r a were taken on a Becknian ACTA MIV spectrophotometer o p e r a t i n g i n the du:i1 -hcdm nioclc. through a dummy c e l l w i t h s a p p h i r e and q u a r t z windows spaced simil a r l y t o t h o s e i n t h e c r y o s t a t and g a s c e l l . Absorbances were manually recorded i n t e r v a l s o f 1(1 A o v e r tlic rLiii:1,c-of i n t e r c~~t . DATA IIANDLING Thc r-cfcrencc hc,lin 1~1 5 5 c d The c o n d i t i o n i n g o f t h e c e l l produced a c o a t i n g on t h e windows t h a t remained c o n s t a n t from one f i l l t o t h e n e x t . T h i s background was recorded, and a computer program was w r i t t e n t o

No abstract

No abstract