Synthesis of 5-hydroxymethylfurural from carbohydrates using large-pore mesoporous tin phosphate

Integrated, cascading enzyme-/chemocatalytic cellulose conversion using catalysts based on mesoporous silica nanoparticles

This article reports a novel approach to deconstructing cellulose into 5-hydroxymethylfurfural (HMF) with a high yield (46.1%) by integrating a sequential enzyme cascade technique in an aqueous system with solid acid catalysis in an organic-solvent system. We executed the rational design and synthesis of mesoporous silica nanoparticles (MSNs) with various pore sizes and surface functionalities, which proved to be useful for the immobilization of various enzymes (i.e., cellulase and isomerase) and nanoparticles (i.e., magnetic Fe3 O4 ) and for functionalization of various acid groups (i.e., H2 PO3 , COOH, and SO3 H). We separately applied the synthesized biocatalysts (i.e., cellulase-Fe3 O4 @MSN and isomerase-Fe3 O4 @MSN) and chemical catalysts (i.e., HSO3 -MSN) in a sequential cellulose-to-glucose, glucose-to-fructose, and fructose-to-HMF conversion, respectively, across both aqueous- and organic-solvent systems after the optimization of reaction conditions (e.g., reaction temperature, water ratio, catalyst amount). The integrated enzymatic and chemocatalytic concept in this study could be an effective and economically friendly process for various catalytic applications.

One-pot, one-step synthesis of 2,5-diformylfuran from carbohydrates over Mo-containing Keggin heteropolyacids

In this work, a one-pot strategy for directly converting fructose into 2,5-diformylfuran (DFF) over Mo-containing Keggin heteropolyacids (HPAs) in open air is developed. H3 PMo12 O40 HPA is found to show high activity and selectivity to the formation of DFF owing to its higher Brønsted acidity and moderate redox potential. The partial substitution of the H(+) in H3 PMo12 O40 with Cs(+) leads to the heterogenization of the HPA by forming its cesium salts Csx H3-x PMo12 (x=0.5, 1.5, and 2.5). A satisfactory yield of 69.3% to DFF is obtained over Cs0.5 H2.5 PMo12 polyoxometalate after deliberate optimization of the reaction conditions. The heterogenized polyoxometalate could be recycled and reused without significant loss of catalytic activity for five runs. The produced DFF could be separated from the resulting mixture by an adsorption-desorption method using activated carbon as the adsorbent and furfural as the desorbent. A highest isolated yield of 58.2% is obtained.

Efficient solid acid catalyst containing Lewis and Brønsted Acid sites for the production of furfurals

Self-assembled nanoparticulates of porous sulfonated carbonaceous TiO2 material that contain Brønsted and Lewis acidic sites were prepared by a one-pot synthesis method. The material was characterized by XRD, FTIR spectroscopy, NH3 temperature-programmed desorption, pyridine FTIR spectroscopy, field-emission scanning electron microscopy, high-resolution transmission electron microscopy, N2 -sorption, atomic absorbance spectroscopy, and inductively coupled plasma optical emission spectroscopy. The carbonaceous heterogeneous catalyst (Glu-TsOH-Ti) with a Brønsted-to-Lewis acid density ratio of 1.2 and more accessible acid sites was effective to produce 5-hydroxymethylfurfural and furfural from biomass-derived mono- and disaccharides and xylose in a biphasic solvent that comprised water and biorenewable methyltetrahydrofuran. The catalyst was recycled in four consecutive cycles with a total loss of only 3 % activity. Thus, Glu-TsOH-Ti, which contains isomerization and dehydration catalytic sites and is based on a cheap and biorenewable carbon support, is a sustainable catalyst for the production of furfurals, platform chemicals for biofuels and chemicals.

Synthesis and evaluation of stable polymeric solid acid based on halloysite nanotubes for conversion of one-pot cellulose to 5-hydroxymethylfurfural

Based on halloysite nanotubes (HNTs), precipitation polymerization and Pickering emulsion polymerization were firstly adopted to synthesize two composites i.e. HNTs–polystyrene(PSt)–polydivinylbenzene(DVB)(i) and HNTs–PSt–PDVB(ii), respectively.