Euro Petrochemistry 2019: Conversion of CH4 into Value-added Chemicals by Plasma-Catalysis-Yanhui Yi-Dalian University of Technology

Methane (CH4), the main component of natural gas and shale gas, has a large reservation and wide distribution in the world, and thus it has been considered as an alternative energy source for oil. However, due to high stability (439 kJ/mol C-H bond energy), negligible electron affinity and low polarizability of CH4？molecule, catalytic conversion of CH4？into value-added chemicals is considered the “holy grail” of catalytic chemistry, and thus effective utilization of CH4？has attracted much attention. Herein, we report a CH4/NH3？plasma reaction promoted by Pt and Cu catalysts for synthesis of hydrocyanic acid (HCN) at low temperature (400？oC).？ HCN, an important chemical in organic chemistry, is widely used in pesticide, medicine, metallurgy, fuel and polymer, but it is currently produced through Andruddow process (1000-1100？oC,？ Pt-Rh alloy gauze catalyst), the reaction of CH4, NH3, and O2, or BMA process (1300？oC, Pt mesh catalyst), the reaction of CH4？and NH3？at atmospheric pressure. That is, the plasma catalysis technology has dramatically lowered the reaction temperature for HCN synthesis. We also report a CH4/O2？plasma reaction promoted by Ni/Al2O3？catalysts for production of CH3OH. Under the conditions of 85a？？, 2:1 CH4/O2？molar ratio, 0.393 s residence time and 30 W discharge power, 66.6 % methanol selectivity is achieved with 6.4 % methane conversion. The Ni/Al2O3？catalysts were characterized by TPR, XRD, XPS and HRTEM, and the results show that the production of CH3OH is mainly attributed to the highly dispersed NiO phase which has a strong interaction with Al2O3？support. In addition, 0D modelling (ZD-Plaskin) results show that CH3OH is mainly produced through the radical reactions CH4？+ O(1D) → CH3O + H？？？CH3O + H → CH3OH and CH3O + HCO → CH3OH + CO Chemical transformations of CO2？into valuea？？added chemicals and fuels have been regarded as a key element for creating a sustainable lowa？？carbon economy in the chemical and energy industry. A particularly significant route that is currently being developed for CO2？utilization is catalytic CO2？hydrogenation. This process can produce a range of fuels and chemicals, including CO, formic acid, methanol, hydrocarbons, and alcohols; however, high H2？consumptions (CO2+3？H2→CH3OH+H2O) and high operating pressures (ca. 30–300a？？bar) are major challenges associated with this process. Instead of using H2, the direct conversion of CO2？with CH4？(dry reforming of methane, DRM) into liquid fuels and chemicals (e.g., acetic acid) represents another promising route for both CO2？valorization and CH4？activation.