Role of naphthalene during the induction period of methanol conversion on HZSM-5 zeolite

The role of methylnaphthalenes in a methanol to hydrocarbons (MTH) reaction on HZSM-5 zeolite was systematically studied on a fixed-bed reaction system. As this is a polycyclic aromatic species, it was interesting to find that co-feeding a small amount of naphthalene could also promote methanol conversion at a low temperature. For the first time, methylnaphthalenes were found to be able to act as initial active HCP species on HZSM-5. The introduced naphthalene could help generate more active methylbenzene HCP species and enhance the aromatic-based cycle during the induction period. As a result, ethene selectivity was promoted due to the co-fed naphthalene. Moreover, despite the large molecular size of naphthalene, it can still function as an active HCP species on the internal acid sites of the HZSM-5 catalyst.