Selective Poisoning by Coke Formation on Pt/AL2O3

Influence of Calcium Addition on Catalytic Properties of PtSn/ZSM-5 Catalyst for Propane Dehydrogenation

“…The first peak at low temperature has been assigned to coke deposited on metallic centers, which is more reactive to oxygen. The second peak appears at higher temperature and corresponds to coke deposited on the support [17,35]. These results imply that the nature of coke could be different on metal and support sites in all catalysts.…”

Characterization of coke deposited on Pt/alumina catalyst during reforming of liquid hydrocarbons

“…This may suggest that steam inhibits the kinetics of the coke formation. This is reasonable since the transformation of the reactants to coke is a sequential process, beginning with dehydrogenation on the metal sites and subsequent cyclization (for tetradecane) and condensation reactions [6,16,28,30,31]. If this is the case, the kinetics of the coking reactions are faster for the POX reaction than for SR.…”

“…Although the CO 2 peaks differ in magnitude, each reaction produced three peaks at about $100, 420, and 550 8C. Low temperature coke (<200 8C) formation is the result of condensation and rearrangement steps and its composition depends on the reactant, whereas the components of high temperature (>350 8C) coke are polyaromatic and result from hydrogen transfer and dehydrogenation reactions [6,16,28,30,31]. The small peak at $80-100 8C can be attributed to reactive coke with a relatively high H/C ratio, which is probably polymeric in nature.…”

Potential of Ni supported on clinoptilolite catalysts for carbon dioxide reforming of methane

“…It has been reported that there is a relationship between the oxidation temperature and the distance between the coke on the metal and the support. Therefore, those carbon deposits left near the metallic particle will be more easily oxidized at a lower temperature than the coke on the support because the coke combustion by oxygen spillover can be catalyzed on the metal [20,21]. The low-temperature peaks observed in TPO of coked Pt/Al 2 O 3 catalysts have been ascribed to the carbon near the metal particles, while those at high temperatures have been ascribed to the carbon over the support [22].…”