Propane hydrocracking and dehydrogenation

Abstract

Hydrocracking and dehydrogenation reaction of propane have been investigated over catalysts in a packed bed reactor. Hydrocracking of propane was carried out over silicaalumina catalyst with no added hydrogen. A brief studies of the mechanism of propane hydrocracking were carried out and coke formation was discussed. Also, the effects of space velocity and temperature on conversion, selectivities and catalyst activity were experimently investigated. In hydrocracking, higher conversion revealed the decrease of propylene yield. At lower conversion the ratio of propylene to ethylene in the product gases was nearly 1.0, and it can be seen that ethylene and propylene were the primary cracking products. But the ratio of ethylene to ethane was about 14.8. Thus, we can see the hydrogenation activity of silica-alumina is low. At relatively higher temperatures, the conversion was more than 90\%, but the selectivity to propylene sharply decreased, while selectivity to ethylene increased nearly to 0.45 at 99\% conversion. In the dehydrogenation of propane over chromia-alumina catalyst, propylene and hydrogen were the main products. At several temperatures, W/F of about 30-35gr.cat/gr propane/hr. was the optimum space velocity to maximize yield of propylene. Maximum yield of propylene. Maximum yield of propylene was about 0.30 at $600\,^\circ\!C$ and 35 W/F. From analog computer simulation, reaction rate constants of each reactions were obtained. The Calculated values of the activation energy from Arrhenius plot were as follows: $$E_a = 47,090 cal/mol$$ $$E_a^{\prime} = 12,790 cal/mol$$ $$E_b = 62,860 cal/mol$$ $$E_c = 47,760 cal/mol$$