The Role of Carbonaceous Residues in Platinum Catalysed Hydrocarbon Reforming Reactions

[摘要] The effect of the deposition of carbonaceous residues on the performance of two different Pt/g-Al2O3 bifunctional reforming catalysts has been studied during continuous flow experiments performed at 500C and 9. 5 atm. using n-heptane as a model hydrocarbon feedstock. With both catalysts, the deposition of carbonaceous residues resulted in an overall decline in catalytic activity. This decline occurred most rapidly during the early stages of the reaction but progressively slowed with increasing time-on-stream until eventually a stable catalytic activity was attained. Significant variations in catalyst selectivity were observed to occur as a consequence of the deposition of carbonaceous residues. Increases in isomerisation selectivity of 11% and 16% occurred for the two catalysts. Corresponding decreases occurred in the aromatisation selectivities (4% and 10%) and hydrocracking selectivities (5% and 6%) of the catalysts, whilst the selectivities with respect of hydrogenolysis remained essentially constant. These selectivity changes are interpreted in terms of a coking process in which the metallic function of the bifunctional reforming catalysts is more selectively poisoned than the acidic function. It is therefore deduced that carbonaceous residues preferentially reside on the metallic function of bifunctional reforming catalysts. Differences in the nature of the individual product yield and selectivity changes observed for the two different catalysts with the deposition of carbonaceous residues, are interpreted in terms of the different metal loadings of the catalysts. In addition, pulse-flow experiments have been performed with n-heptane at 500

[发布机构] University:University of Glasgow

[关键词] Inorganic chemistry