Coke formation over Pt-Sn-K/Al2O3 in C-3, C-5-C-8 alkane dehydrogenation

The effect of reactants on coke formation during dehydrogenation (DH) over 0.3 wt.%Pt-0.3 wt.%Sn-0.6 wt%K/Al2O3 was investigated. The reactions were c arried out in the temperature range 200-600 degrees C at 1 atm with pairs o f alkanes and alkenes (C-3, C-5-C-8). The carbonaceous deposits formed duri ng the process were analyzed using the temperature-programmed oxidation (TP O) technique. With the same amount of coke, the TPO profiles of the short a lkane and alkene (C-3) did not match completely, while those of the larger chain alkanes and alkenes (C-5-C-8) were virtually identical. From these re sults, a simple model of coke formation has been proposed. Short alkane DH provides coke in series and larger alkane DH generates coke in series and c onsecutive modes. (C) 2000 Elsevier Science S.A. All rights reserved.