Silicotungstic acid (HSiW) encapsulated UiO-66 nanocatalyst have been successfully synthesized by one-pot synthesis strategy and used as a stable and highly efficient catalyst for esterification.

Phosphomolybdic acid was sequentially incorporated into a highly porous metal–organic framework by a one-pot synthesis method, and the prepared composite was used as an efficient and stable solid acid catalyst for biodiesel production.

An attempt has been made to optimize the preparation of biodiesel from the transesterification of oleic acid with methanol over iron(III)-doped phosphomolybdic acid (H 3 PMo) catalysts. The prepared doped H 3 PMo salts were characterized using powder X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. The detailed characterization results demonstrated that the doped H 3 PMo salts have a strong interaction between the iron(III) ions and metal oxygen cluster, well preserving a typical Keggin structure of heteropolyacids and possessing good thermal stability. The effect of esterification reaction parameters was investigated and optimized using single-factor experiments method in combination with response surface methodology (RSM). The doped catalyst exhibited good catalytic activity, affording the oleic acid conversion of 89.2% with single factor optimization and 95.1% with RSM. More importantly, the catalyst was simply separated by decantation and exhibited good stability, with the oleic acid conversion of 70.2% after three consecutive cycles. Besides, this catalyst can also catalyze the esterification of other free fatty acids. Therefore, the doped H 3 PMo catalyst is a promising candidate for eco-friendly production of biodiesel in industry.

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Direct conversion of fructose into 5-hydroxymethylfurfural (HMF) is achieved by using modified aluminum-molybdenum mixed oxide (S-AlMo) as solid acid catalysts. The synthesized catalyst was characterized by powder XRD, nitrogen adsorption-desorption isotherm, NH3-TPD, and SEM. As a result, the presence of strong acidity, mesostructures, and high surface area in the S-AlMo catalyst was confirmed by nitrogen adsorption-desorption isotherm and NH3-TPD studies. A study by optimizing the reaction conditions such as catalyst dosage, reaction temperature, and time has been performed. Under the optimal reaction conditions, HMF was obtained in a high yield of 49.8% by the dehydration of fructose. Moreover, the generality of the catalyst is also demonstrated by glucose and sucrose with moderate yields to HMF (24.9% from glucose; 27.6% from sucrose) again under mild conditions. After the reaction, the S-AlMo catalyst can be easily recovered and reused four times without significant loss of its catalytic activity.