(Ga, Al)-H-MFI\nCatalysts with Highly Dispersed Ga\nSites and Proximal Protonic Sites Enable Methane–Propane Coaromatization

Methane–propane coaromatization (MPCA) upgrades\ntwo abundant\nand inexpensive light alkanes into value-added aromatic products.\nWhile Ga-loaded MFI zeolites represent by far the most promising catalysts\nfor MPCA reaction, they often contain a sizable portion of Ga species\nat the external surface of zeolites, which are remote from the Brønsted\nacid sites (BAS) within MFI pores and thus inefficient for MPCA. Here,\nwe show that Ga can be introduced into MFI pores at fairly high loadings\nvia a simple cocrystallization approach, yielding catalysts possessing\nwell-dispersed Ga sites predominantly residing inside the pores and\nframework. Adjacency between Ga and BAS within the constraints of\nMFI channels makes these (Ga, Al)-H-MFI catalysts more active toward\nmethane and propane activation and more selective toward aromatics\ncompared to the Ga/MFI counterparts prepared by impregnation that\ninevitably leaves a large fraction of Ga at the external surface (i.e.,\nwithout confinement and few adjacent BAS). Further, the effects of\nthe Si/Al ratio on MPCA performance have been investigated for (Ga,\nAl)-H-MFI catalysts. Due to the multifold roles of BAS in the overall\nreaction sequence, an increased BAS concentration generally results\nin higher propane conversion and productivity of aromatics together\nwith lower net methane conversion and severer coking.