Using greenhouse gases in the synthesis gas production processes: Thermodynamic conditions

Abstract

The work concerns the thermodynamic analysis of CH4 reforming with various oxidants (CO2, H2O, O2) in the technological variants DRM (Dry Reforming of Methane) and TRM (Tri-reforming of Methane) technological variants. Both processes of synthesis gas production (raw material for the production of value-added products) are problematic in terms of environmental protection. In the process, two components of greenhouse gases are used as a substrate: CO2 and CH4. The influence of temperature, pressure, and the molar ratio of oxidants to methane on the efficiency of both processes was analyzed using the deterministic method: raw material conversion, product efficiency and selectivity - H2 and CO, and the value of the H2/CO ratio characterizing the suitability of the synthesis gas for various syntheses. The problem of carbon deposition tendency in DRM was minimized through the selection of operational process conditions, and in the case of TRM, it was fully reduced. The deterministic method of non-linear programming by defining the objective function with constraints helped formulate allowed one the values of TRM parameters: complete reduction of the coking problem, maintaining the H2/CO ratio at the desired level - 2 and CO2 conversion equal to 90%, led to a hydrogen efficiency of over 90%. This efficiency can be obtained at the process temperature T = 273 K, with a pressure of 1 atm, and the molar ratios of oxidants to methane: CH4/CO2/H2O/O2 = 1/0.36/0.77/0.01.