Bentonites Modified with Phosphomolybdic Heteropolyacid (HPMo) for Biowaste to Biofuel Production

Abstract

Two bentonites from Paraíba (Northeastern Brazil) were impregnated with heteropoly phosphomolybdic H3PMo12O40 (HPMo). The materials produced were characterized by various techniques such as N2 adsorption-desorption (specific surface area, SSA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), Thermogravimetric analysis (TGA/DTG), Scanning Electron Microscopy (SEM) equipped with Dispersive Energy X-ray spectroscopy (EDS), ultraviolet-visible spectroscopy (UV-vis), acid-base titration analysis. The catalytic activity of these materials was tested in the esterification of a waste from palm oil deodorization and the main results obtained (about 93.3% of conversion) indicated that these materials have potential to act as heterogeneous solid acid catalysts. The prepared materials exhibited satisfactory catalytic performance even after a very simple recycling process in three reuse cycles, without significant loss of their activities.

Acetylation of Eugenol over 12-Molybdophosphoric Acid Anchored in Mesoporous Silicate Support Synthesized from Flint Kaolin

“…The HPMo anchored to the AlSiM was synthesized by impregnation according to Pires et al [30] and Oliveira et al [28]. Each gram of AlSiM was dispersed under vigorous stirring in a 0.1 mol L −1 aqueous HCl solution, which already contained the desired amounts of HPMo (0.11 g, 0.25 g and 0.43 g).…”

“…The solid obtained was pulverized and dried at 120 °C for 12 h and finally calcined at 200 °C for 4 h at a heating rate of 10 °C min −1 . The samples obtained were designated as xHPMo/AlSiM, where x refers to the percentage of HPMo supported in the AlSiM, which varied in 10%, 20% and 30% by mass, according to Scheme 2 [28].…”

“…To eliminate excess HPMo on the surface of the material, which could contribute to homogeneous catalysis during the reaction, the xHPMo/AlSiM was subjected to a washing step. The xHPMo/AlSiM (3 g) was inserted into a Soxhlet extractor where it was washed with ethanol (300 mL) under constant reflux for 24 h, according to the procedure, adapted from the literature [28,51]. Thus, the measurement of HPMo in the washing solvent in the Soxhlet extractor also made it possible to indirectly estimate the amount of HPMo immobilized efficiently by ultraviolet-visible (UV-vis) spectroscopy [28,51].…”

“…Thus, the use of heterogeneous catalysts is particularly advantageous because they are versatile, possess high operational efficiency under moderate reaction conditions, and additionally they provide a more ecological and economical route for esterification reactions [25,26,27,28,29,30,31]. In recent years, some acidic solids have been used as catalysts for the esterification or acetylation of eugenol, for example modified acid zirconia (UDCaT-5) [2] and ionic resins [10,11,12], which not only can be easily recovered and reused, but also favored the development of continuous production processes for a series of industrially important productions.…”

“…Our research group has aimed to add value to wasted kaolinite as alternative to minimize environmental impacts. Previous studies showed wasted kaolinite as feedstock for catalyst synthesis [25,26,29,31], catalytic supports [30,49] and for mesoporous aluminosilicate synthesis [27], for all cases, they were efficient for the esterification of free fatty acids, directed to the field of the production of biofuels [25,26,27,28,29,30,31]. The flint kaolin also shows potential as a starting material for zeolite synthesis [47].…”