Hu Pan

Efficient conversion of furfuryl alcohol to ethyl levulinate with sulfonic acid-functionalized MIL-101(Cr)

Catalytic ethanolysis of furfuryl alcohol (FA) to ethyl levulinate (EL) with MIL-101(Cr)–SO3H, prepared by simple one-pot hydrothermal treatment, is presented for the first time. The as-prepared catalyst with high surface area, hydrothermal and chemical stability, good dispersion, and feasible accessibility of –SO3H Bronsted acid sites was found to show superior performance to other sulfonic acid-functionalized solid catalysts. Besides the special textural properties, the obtained good catalytic activity of 79.2% EL yield and 100% FA conversion were also dependent on the density and strength of the Bronsted acid and the reaction parameters. A slight loss of catalytic activity after five consecutive recycles and the hot filtration experiment confirmed the good stability of MIL-101(Cr)–SO3H. Two coexisting reaction paths for the ethanolysis of FA to EL catalyzed by MIL-101(Cr)–SO3H were proposed, wherein 2-ethoxymethylfuran (2-EMF) was observed to be the dominant intermediate.

MIL-100(Fe)-catalyzed efficient conversion of hexoses to lactic acid

MIL-100(Fe) was used for the first time in the catalytic transformation of hexose sugars into lactic acid (LA). The as-synthesized MIL-100(Fe) was systematically characterized, and its superior morphological and textural properties were demonstrated to contribute greatly to the pronounced catalytic performance in fructose-to-LA conversion (up to 32% yield), as compared with other catalysts like Cu-BTC and MIL-100(Cr). The effects of reaction conditions including temperature, reaction time, and substrate loading were explored. In addition, MIL-100(Fe) could be easily reused for 4 cycles with no evident decrease in catalytic activity.

Polyoxometalate-MgF2 hybrids as heterogeneous solid acid catalysts for efficient biodiesel production

A series of highly active and stable Keggin heteropolyacid catalysts were prepared through mixing of 12-tungstophosphoric acid (TPA) with magnesium fluoride (MgF2). Among those acidic catalysts, the Mg20F39TPA-1.0 hybrid with moderate acidity (0.96 mmol g−1) and good dispersion of active sites presented pronounced catalytic performance in esterification of oleic acid (up to 95% oleic acid conversion). Particularly, Mg20F39TPA-1.0 was also efficient for the transesterification of Jatropha oil with a high acid value, giving biodiesel in 93% yield. Moreover, the catalyst showed good durability and reusability for at least five consecutive cycles.

Production of Biodiesel via Simultaneous Esterification and Transesterification

Biodiesel is considered as a substitute for fossil-based diesel fuels because of its renewability and environmental friendliness. Biodiesel is generally produced by transesterification of oils or esterification of free fatty acids with methanol. In these production procedures, basic and acidic catalysts enhance biodiesel yields under mild conditions. Particularly, heterogeneous acids promote simultaneous (trans)esterification in a single pot for biodiesel production (free of soap formation) from cheap raw materials containing high contents of free fatty acids, which cannot only avoid complex separation processes involved in pre-esterification, but also simplify catalyst separation and reuse, thus greatly reducing the cost. This chapter reviews the synthesis of biodiesel via simultaneous (trans)esterification catalyzed by mixed metal oxides, acidic ionic liquids, carbon-based solid acids, magnetic solid acids and hybrid solid acids. Advantages of heterogeneous catalytic reaction systems are discussed. Guidance is given on improving the performance of heterogeneous acid catalysts for production of biodiesel.

Mesoporous (Ta, Nb)3W7 Modified with Stearic Acid Used as Solid Acids for Esterification

Mesoporous solid acids Ta3W7 and Nb3W7 were prepared from TaCl5 and NbCl5 with WCl6 in the presence of stearic acid (SA) via a sol-gel method, respectively. For comparison, mesoporous Ta3W7-P123 mixed oxides and mesoporous Nb3W7-P123 mixed oxides were synthesized in the same way. The catalysts were characterized through TGA, XRD, SEM, TEM, BET, and NH3-TPD. Experimental results showed that Ta3W7-SA and Nb3W7-SA exhibited several advantages such as higher activity, shorter preparation period, lower cost, stronger acid sites, and higher surface area, which had potential to be used as mesoporous heterogeneous catalysts in biodiesel production.