Infrared study of carbon deposits on bimetallic catalysts. Final report, 1 September 1986--30 May 1994

摘要

The study investigated coke deposited on alumina, on platinum/alumina, and on bimetallic/alumina catalysts. The interest in coke is based on coke deposition being the limited factor in the processes used to produce gasoline. The success of the bimetallic catalysts can be related to their effect on coke deposition. The consensus view has been that coke deposits on catalysts are a complex species composed of carbon and hydrogen in which the hydrogen/carbon ratio is inversely related to the temperature to which the coke has been heated. A new factor was introduced when infrared studies detected bands at 1580 and 1470 cm(sup 1), Isotropic substitution studies showed that these bands are due to an oxygenated species similar to a carboxylate. During the fifth year of the project, it was shown that the oxygen needed to convert hydrocarbons to carboxylate are provided by the more basic hydroxyls on the alumina surface. Carboxylates were not observed in coke deposited on zeolites under conditions which produced carboxylates on alumina. This difference is attributed to the absence of strongly basic hydroxyl groups in zeolites. During the final sixth year this work was extended to show that treatment of alumina with hydrogen sulfide eliminates carboxylate formation. Results from this study are discussed. (ERA citation 19:033776)