Development of an Active and Mechanically Stable Catalyst for the Oxidative Coupling of Methane in a Gas–Solid Vortex Reactor

Abstract

The high gas−solid slip velocity and the resulting intensified heat and mass transfer make gas−solid vortex reactors (GSVR) a promising reactor technology for the oxidative coupling of methane (OCM). The short gas residence time and high solid velocity in the GSVR require a highly active catalyst with strong attrition resistance. Conventional Sr/La 2 O 3 catalysts possess sufficient activity; however, these materials lack mechanical strength. In this study, a novel active and mechanically strong catalyst is developed by supporting a conventional Sr/La 2 O 3 OCM catalyst on a porous SiC support. The Sr−La−O/SiC catalyst shows a very high activity for the OCM in a fixed-bed lab-scale reactor. More importantly, the Sr−La−O/SiC catalyst displays high attrition resistance in standardized attrition tests and forms a stable rotating fluidized bed in the GSVR during a hot flow experiment at 946 K for more than 1 h. Shape characterization of the catalyst particles collected from a hot flow experiment suggests friction rather than fragmentation as the dominant attrition mechanism. Finally, the Sr−La−O/SiC catalyst was successfully tested under reactive conditions in the GSVR at 1080 K, showing a methane conversion of around 6% and a C 2 yield of 2% for an estimated space-time of 0.25 kg cat s mol CH 4 −1 .

Numerical Investigation of the Effect of Inhomogeneous Flow Behaviors inside a Particle Cluster in the OCM Reaction

“…Selecting applicable reactors is as critical as choosing appropriate catalysts for improving the selectivity and yield of the OCM reaction, which has been a key focus in the OCM research field. Fluidized bed reactors are employed for the OCM reaction to effectively remove excessive reaction heat and prevent deep oxidation of hydrocarbons, compared with conventional fixed bed reactors. − However, a distinct challenge of fluidized bed reactors is the presence of particle cluster (or agglomeration), which lead to the decline of gas–solid contact and heat transfer efficiency, impeding efficient catalysis and resulting in the formation of byproducts. Marco et al noted that the formation of particle clusters was linked to the high-temperature melting of catalyst particles, which may lead to undesirable side reactions.…”