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In the present study, phosphomolybdic acid (HPMo) supported on Cu-BTC Metal-organic frameworks (MOFs) were prepared and utilized as a solid acid catalyst. The structure of the synthesized materials was characterized by using powder XRD, FT-IR, N2 adsorption-desorption, SEM, TEM, TG, and NH3-TPD techniques. These results exposed that HPMo was successfully encapsulated in the Cu-BTC cage and the Keggin structure of HPMo was maintained in the composite catalyst. In addition, the catalytic activity and recovery properties of the HPMo/Cu-BTC catalyst for the esterification of oleic acid with methanol into biodiesel were evaluated. These results showed that the HPMo/Cu-BTC catalyst exhibited high conversion (93.7%) and excellent reusability due to its mesoporous structure, excellent acidic activity, high BET surface area, large pore volume, and good thermal stability. Meanwhile, the kinetic studies of the esterification reaction revealed that it follows pseudo-first-order kinetics with a low activation energy of 37.5 KJ/mol. More interestingly, it shows potential application for esterification of free fatty acids (FFAs) or pretreatment of low-cost feedstocks contain high FFAs content for the green production of biodiesel. [ABSTRACT FROM AUTHOR]

In this study, the silver-exchanged heteropolyacids were prepared by a simple and environmentally friendly ion exchange method, were found to be active in the esterification of oleic acid with methanol to produce biodiesel. The catalysts were characterized by X-ray diffraction (XRD), Fourier transform infrared (FT-IR) and scanning electron microscopy (SEM), separately. The effect of various factors was investigated to optimize the reaction conditions. The results showed that the oleic acid conversion can reach 91.3% after reacting for 3 h at 70°C, with oleic acid to methanol ratio of 1:10 and the amount of catalyst of 5 wt.%. Moreover, the catalyst could be easily separated from the reaction mixture and used repeatedly for five cycles with the oleic acid conversion over 50.1%, due to its relative stability. In particular, this catalyst can also catalyze other esterification of fatty acids with different chain length of carboxylic acid and high acid value non-edible oils, which may provide significant benefits for developing an environmentally benign and continuous process for synthesizing biodiesel in the future. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]