Thermocatalytic Conversion of Natural Gas to Petrochemical Feedstocks Via Non-oxidative Methods: Theoretical and Experimental Approaches

Requirement of efficient technologies to convert natural gas (methane) into value-added products such as ethylene, aromatics (BTX), methanol and DME is prompted due to recent discovery of large reserves of shale and natural gas. To date, different direct and indirect processes have been explored involving all oxidative/non-oxidative routes. Direct conversion of methane into liquid aromatic hydrocarbons under oxygen-free environment (non-oxidative routes) is one of the promising approaches for natural gas upgradation. Direct methane to aromatic conversion which is also known as methane dehydroaromatization (MDA) reaction is performed at a temperature above 600 °C and atmospheric pressure producing benzene as major product and hydrogen as by-product. Lower thermodynamic equilibrium conversion and fast catalyst deactivation are the major challenges with the reaction which restricts its commercialization. Mo/HZSM-5 and Mo/HMCM-22 are the well-known catalysts used for this reaction showing >90% benzene selectivity with 11% methane conversion at 700 °C. Fast catalyst coking due to carbonaceous deposits results in a lower yield of aromatic products. This can be controlled via different experimental treatments such as tuning in catalytic constituents, co-feeding with H2 and oxygenates (CO2, CO, steam) and reactor design including catalyst regeneration protocol. Mechanistic studies of MDA reaction also provide insights to control coke content by identifying active sites. With this purpose, here we intend to deliver insights on MDA reaction catalysed by zeolite-supported molybdenum catalyst and investigations on catalyst stability controlling coke deposition by providing an overview of combined theoretical and experimental studies. In this book chapter, different ways to control the catalytic activity and stability have been discussed based on catalytic parameters and reactor configurations.