A Study into the γ-Al2O3 Binder Influence on Nano-H-ZSM-5 via Scaled-Up Laboratory Methanol-to-Hydrocarbon Reaction

Abstract

Development of a laboratory selected zeolite into an industrial zeolite-based catalyst faces many challenges due to the scaling-up of reaction which requires many upgrades of the as-prepared catalyst such as an enhanced physical strength. To meet this requirement zeolite powders are normally mixed with various binders and then shaped into bulky bodies. Despite the fact there are a lot of reports on the positive features brought by the shaping treatment, there is still a great need to further explore the zeolite properties after the binder introduction. In this case, a lot of studies have been continuously conducted, however, many results were limited due to the usage of much smaller laboratory samples rather than a real factory plant, and more importantly, the maximal/minimal proportion of zeolites in the shaped catalyst. In this research, our shaped catalysts are based on nano-H-ZSM-5 zeolites and alumina (γ–Al2O3) binder while keeping the zeolite content to a maximum. H-ZSM-5 samples and Al-H-ZSM-5 samples are compared in the designed methanol-to-hydrocarbons reaction. With a reduced weight-hourly-space-velocity (WHSV = 1.5 h−1) and a higher reaction pressure (6 bar) favorable for aromatization, together with the tailored instruments for catalyst volume scale-up (20 g samples are tested each time), our tests focus on the early period catalytic performance (during the first 5 h). Unlike a normal laboratory test, the results from the scaled-up experiments provide important guidance for a potential industrial application. The role of the γ–Al2O3 introduced, not only as binder, but also performing as co-catalyst, on tailoring the early time product distribution, and the corresponding coke deposition is systematically investigated and discussed in details. Notably, the Si/Al ratio of H-ZSM-5 still has a decisive influence on the reaction performance of the Al-H-ZSM-5 samples.