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

In the present work, an efficient and stable WO _X /MCM-41 solid acid catalyst was prepared by the wet impregnation method. The characterization of powder X-ray diffraction, transmission electron microscopy, ultraviolet-visible, H₂ temperature-programmed reduction, X-ray photoelectron spectroscopy, NH₃ temperature-programmed desorption, and N₂ adsorption-desorption isotherms confirmed that the impregnation amount and calcination temperature of WO _X speciation affected the dispersity and acidity of the resulting catalyst. This WO _X /MCM-41 solid acid catalyst was subsequently applied in the ketalization reaction of glycerol and acetone to produce solketal. By catalyst screening and reaction condition optimization, WO _X /MCM-41 obtained by impregnating 20 wt % and calcining at 350 °C exhibited the highest solketal yield and catalytic stability.

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

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.

Continuous Flow Upgrading of Selected C2-C6 Platform Chemicals Derived from Biomass

The ever increasing industrial production of commodity and specialty chemicals inexorably depletes the finite primary fossil resources available on Earth. The forecast of population growth over the next 3 decades is a very strong incentive for the identification of alternative primary resources other than petro-based ones. In contrast with fossil resources, renewable biomass is a virtually inexhaustible reservoir of chemical building blocks. Shifting the current industrial paradigm from almost exclusively petro-based resources to alternative bio-based raw materials requires more than vibrant political messages; it requires a profound revision of the concepts and technologies on which industrial chemical processes rely. Only a small fraction of molecules extracted from biomass bears significant chemical and commercial potentials to be considered as ubiquitous chemical platforms upon which a new, bio-based industry can thrive. Owing to its inherent assets in terms of unique process experience, scalability, and reduced environmental footprint, flow chemistry arguably has a major role to play in this context. This review covers a selection of C₂ to C₆ bio-based chemical platforms with existing commercial markets including polyols (ethylene glycol, 1,2-propanediol, 1,3-propanediol, glycerol, 1,4-butanediol, xylitol, and sorbitol), furanoids (furfural and 5-hydroxymethylfurfural) and carboxylic acids (lactic acid, succinic acid, fumaric acid, malic acid, itaconic acid, and levulinic acid). The aim of this review is to illustrate the various aspects of upgrading bio-based platform molecules toward commodity or specialty chemicals using new process concepts that fall under the umbrella of continuous flow technology and that could change the future perspectives of biorefineries.