Utilization of methane: methylation of benzene with methane and gas-to-liquids (GTL) via fischer-tropsch synthesis

Abstract

During the past decades, studies on the conversion of methane, a main component of natural gas, into more valuable fuels or chemicals have received much attention. This is because liquid-petroleum reserves are becoming scarcer, while natural gas (e.g., methane) reserves are abundant; moreover, methane can be generated by fermentation of organic materials. Previously, methane was predominantly used for heating, in both industry and in households. Once the gas-to-liguids (GTL) technology for the conversion of methane into higher valued liquid products (e.g., gasoline, diesel, and methanol) was accomplished, it has largely inspired many researchers to widen research in this area by either developing a new approach of utilizing methane or improving the performance of existing technologies. In this thesis, the work is divided into two parts. First, methylation of benzene with methane, a novel and challenging approach is aimed at directly using methane as an alkylating agent to react with the benzene ring into methylated product, especially xylenes, in a one-step process. Ag/HZSM-5 and Mo/HZSM-5 were studied as catalysts. The second study was on the heart of GTL technology, Fischer-Tropsch synthesis, a reaction to produce long chain hydrocarbons, which can be hydrocracked to produce gasoline, diesel, jet fuels, and waxes, from synthesis gas derived from methane/natural gas. The capability of some transition metals as metal promoters for Co/AI2O3 Fischer-Tropsch catalyst was demonstrated. Moreover, reoxidation of tiny cobalt crystallite at the onset of the reaction was explored and proposed as one of the modes of catalyst deactivation for very small Nano crystallites.