Conversion of acetylene and ethylene into higher molecular weight hydrocarbons over HZSM-5 catalysts.

摘要

This research is part of a newly developed process to convert methane into liquid fuels. It consists of two main units, a methane pyrolysis reactor and a catalytic fixed bed reactor. The effluent of the first reactor enters the catalytic reactor where the mixture of gases reacts over a solid acid catalyst to produce liquid fuels. The catalytic fixed bed reactor is the focus of this dissertation.; Reactions of acetylene or ethylene over HZSM-5 are investigated. The effect of the feed composition on the catalyst activity, product distribution, average carbon number, and conversion is studied. Co-feeding methane with acetylene decreases the rate of catalyst deactivation compared to the effect of co-feeding nitrogen.; The effect of alumina binder on the activity of HZSM-5 (30) is investigated. HZSM-5 powder gives a higher average carbon number than that obtained from alumina-bound HZSM-5, however, alumina-bound HZSM-5 experiences slower deactivation rate.; The effect of modifying the catalyst with different transition metals is studied. HZSM-5 (30) was modified with palladium, platinum, nickel, cobalt, nickel-cobalt, or copper-gallium. Impregnating the catalyst with transition metals prevents catalyst deactivation. Palladium-loaded HZSM-5 (30) shows superior results over all other metal-loaded catalysts. (Cobalt-nickel)-ZSM-5 (30) gives a slightly lower average carbon number and slightly more heavy components in the product stream compared to those obtained from palladium-loaded HZSM-5 (30). Nickel-loaded HZSM-5 (30) also yields a significant amount of heavy products that is lower than that obtained by Pd/ZSM-5 (30) and (CoNi)/ZSM-5 (30) but greater than that obtained by non-loaded alumina-bound HZSM-5 (30). Platinum-loaded HZSM-5 (30), cobalt-loaded HZSM-5 (30), and (copper-gallium)-loaded HZSM-5 (30) give lower amounts of heavy products compared to those obtained from the catalysts mentioned earlier.; The strength, density, and nature of the acid sites for HZSM-5 with different silica to alumina ratios are determined. In addition, the surface area and pore volume are also determined. The effect of alumina and silica binders on the acidity, surface area, and pore volume of the catalysts is investigated.; A kinetic model is developed and the kinetic parameters for acetylene reaction are determined from the experimental data using modeling and simulation software (Simusolv).