Thesis (M.Eng.)--Chulalongkorn University, 1997

The effect of reactants on coking formation in dehydrogenation over 0.3wt%Pt-0.3wt%Sn-0.6wt%K/Al2O3 was investigated in this research. The reactions were carried out at the temperature range of 200-600 ํC and pressure of 1 atm. Pairs of alkanes and alkenes (C3, C5-C8) are chosen as reactants. Carbonaceous deposits produced during the process were analyzed by temperature programmed oxidation (TPO) technique. Consider activities, amount of coke, and selectivities of coke formation for entire species, reactants having three carbon atoms produce coke in series pathway and reactants having five through eight carbon atoms produce coke following parallel pathway. With the same amount of coke, the TPO profiles of the series coke formation do not necessary match completely, while those of the parallel coke formation are nearly matched. A simplify model of coke formation is proposed and found to be useful in practice.