TITLE: Chemical Trapping of CO/H sub 2 Surface Species.

AUTHOR: J. A. Williams;   D. G. Blackmond;   I. Wender.

INST.  AUTHOR: Pittsburgh Univ., PA. Dept. of Chemical and Petroleum Engineering.

SPONSOR: Department of Energy, Washington, DC.

LANGUAGE: English

PUB.  TYPE: Technical Report

PUB.  COUNTRY: United States

SOURCE: Department of Energy [DE],  1985,  6p.

NTIS ORDER NO.:  DE86011591/INW

ABSTRACT:

CO hydrogenation reactions over supported metal catalysts can produce a wide spectrum of hydrocarbon and oxygenated compounds depending to a large extent on the type of metal used. Elucidating the nature of the intermediate species formed on metal surfaces may provide the key to understanding the pathways through which these reactions proceed on different metals. The investigators are using a trapping technique which involves introducing an alkylating reagent onto the catalyst surface after it has been contacted with the CO/H sub 2 reactants. It is postulated that the reagent reacts with the surface intermediate species by alkylating it at each point of former attachment to the catalyst surface. Identification of the products of this alkylation reaction may then lead to back-deduction of the identity of the surface species itself. Preliminary chemical trapping experiments were carried out in-situ under CO hydrogenation conditions on a 3% RuKY zeolite catalyst. The addition of CH sub 3 I to a CO/H sub 2 reaction stream resulted in a profound alteration of the typical ASF product distribution for this catalyst. A dramatic decrease in C sub 1 to C sub 3 hydrocarbons was observed concomitant with a similarly sharp increase in C sub 4 to C sub 6 hydrocarbons. The distribution of C sub 4 products was also significantly altered. These results indicate that addition of the trapping reagent causes perturbations in the observed CO/H sub 2 products which may be caused by alkylation of surface species by the reagent. However, the complexity of the results make it difficult to clearly identify surface species or to understand the action of the trapping reagent on these surface species.  Investigations are continuing using model organometallic complexes for the catalyst-adsorbate systems. 7 refs., 3 figs. (ERA citation 11:035420)

REPORT  NUMBER: DOE/PC/80526-T4

CONTRACT  NUMBER: FG22-85PC80526