Continuous Flow Synthesis of a ZSM-5 Film in Capillary Microchannel for Efficient Production of Solketal

Abstract

This work presented the microfluidic preparation of zeolite film in a capillary microchannel with different length-to-diameter ratios. In the quartz capillary with an inner diameter of 0.53 and 0.32 mm, Zeolite Socony Mobil-5 (ZSM-5) film was prepared by a continuous flow hydrothermal method. Considering the chemically inert surface of quartz capillary and the difficulty of preparing uniform and continuous zeolite film by conventional static synthesis, the ZSM-5 seed layer was precoated as active sites to induce film growth. The parameters of length-to-diameter ratio, seed coating, feed flow rate, and synthesis time were investigated. It revealed that the crystallinity of the ZSM-5 film was significantly affected by the capillary length-to-diameter ratio and seed coating in this flow system. The film morphology and thickness could be precisely controlled by adjusting the feed flow rate and synthesis time. This hydrogen form of the ZSM-5 (HZSM-5) film capillary microreactor was applied in the ketalization reaction of glycerol with acetone to produce solketal. The single-pass yield of solketal could reach ∼30% under mild conditions. This work provided a convenient stratagem of preparing zeolite catalytic coating or other support coatings in closed microchannels with a high length-to-diameter ratio and the potential application in valuable transformation of biomass glycerol.

Sustainable Upgrade of Bioderived Glycerol to Solketal through Acetalization over Metal-Free Mordenite Catalysts

“…Therefore, the development of a metal-free economical catalytic process for glycerol acetalization is desirable. In this regard, a few metal-free catalysts have been explored for the glycerol-to-solketal conversion. − For example, SiO 2 -supported p -phenolsulfonic acid showed 86% glycerol conversion with 97% solketal selectivity . Even so, sulfur leaching was observed during the reaction.…”

Preparation of the WOX/MCM-41 Solid Acid Catalyst and the Catalytic Performance for Solketal Synthesis

“…Finally, the oven temperature reduced rapidly to 100 °C. The yield of solketal was calculated by an external standard method, in which the external standard reagent was DMF . The expression was as follows: Y SKT was the solketal yield, f SKT was the relative correction factor of solketal versus DMF, A SKT was the area of the solketal peak, A DMF was the area of the DMF peak, m DMF was the added mass of DMF, m GLY was the mass of glycerol, M GLY was the relative molecular mass of glycerol (92.09 g/mol), and M SKT was the relative molecular mass of solketal (132.16 g/mol). …”

Catalytic Enhancement of Cyclohexene Hydration by Ga-Doped ZSM-5 Zeolites

“…The acidic properties of ZSM-5 zeolites are related to the presence of protons compensating the negative charge generated by the trivalent Al atom substituting Si atoms in tetrahedral sites (T-sites). The resulting acidic bridging hydroxyl (Si–(OH)–Al) sites, also known as Brønsted acid sites, have opened zeolites as solid acid catalysts in the ketalization of glycerol with acetone, aromatization of methanol, oligomerization of propene, and methanol-to-olefins and cyclohexene hydration reactions. − The acidity of ZSM-5 zeolites is considered to provide active sites to tailor conversion and selectivity in a given reaction. Surprisingly, isomorphous substitution of Al atoms in tectosilicate frameworks is not the only pathway to improve the catalytic properties of zeolites.…”