Reaction engineering of oxidative coupling of methane: Experimental observations and analysis of the impacts of operating parameters

Abstract

Performance of Oxidative Coupling of Methane (OCM) reactor using the research benchmark Mn-Na2WO4/SiO2 catalyst under various sets of operating conditions was experimentally investigated. In particular, the impacts of varying the operating parameters (630 combination-sets) namely; reactor set-temperature (in 6 levels in the range of 750–875 °C), feed flow-rate (in 5 levels in the range representing GHSV -Gas Hourly Space Velocity- of 9600-19200 cm3 g−1 h−1), methane-to-oxygen ratio (CH4/O2 in 7 levels in the range of 1.5–10), and inert gas dilution (in 3 levels at 0%, 25% and 50%) on the recorded trends of methane-conversion and selectivity and yield of the desired products (C2: C2H4&C2H6) were systematically reviewed. The performed experimental analysis enabled determining the impact of each investigated parameter as well as their interactive impacts through a carefully designed set of experiments. The novel proposed contour graphs visualized how the temperature and methane-to-oxygen ratio for instance directly influence the contribution of the catalyst or indirectly affect the reactor performance in synergy with the variation of dilution and feed flow due to their thermal impacts via affecting the intensity of the gas-phase and catalytic reactions in reactor-scale. It was demonstrated that in wide ranges of variation of these operating parameters, the recorded OCM reactor performance for instance in terms of the observed selectivity represent the interactive impacts of the intrinsic characters of the catalyst and the reactor’s characteristics such as its dimension and thermal capacity. Therefore, these aspects should be carefully considered in design of experiments and in the interpretation of the experimental observations for the research purposes as well as in the design and operation of large-scale reactors.