In this work, the transesterification of soybean oil with methanol using layered heterogeneous catalysts to produce biodiesel was studied. The zinc hydroxy acetate salt Zn₅(OH)₈(CH₃COO)₂·4H₂O (abbreviated Zn–Ac) and the zinc hydroxy nitrate salt Zn₅(OH)₈(NO₃)₂·2H₂O (abbreviated Zn–Nit), which have a layered structure, were synthesized (chemical precipitation) and characterized by X-ray diffraction, infrared spectroscopy, scanning electron microscopy, particle size distribution measurements, specific surface area determination and thermogravimetric analysis. Zn–Ac and Zn–Nit were tested in the transesterification of soybean oil at 100 °C for 2 h. Zn–Nit presented 83.9% oil conversion with 51.5% FAME yield, and it was stable in three consecutive tests, showing good tolerance to aqueous content. Zn–Ac was not stable. The salts transformed into Zn glycerolate at 140 °C in the reaction medium.

In this work, the degradation of methylene blue (MB) in aqueous solution by a heterogeneous Fenton-like process was studied. Nb₂O₅ supported on an anodized aluminum monolith was used as catalyst. The Nb₂O₅ coating generated during the catalyst synthesis was uniform and porous, with a thickness of 7 μm. Response surface methodology was used to study the relationship between process variables and MB degradation and chemical oxygen demand (COD) reduction. The optimal operating conditions were: initial MB concentration of 45 mg L^− 1, initial H₂O₂ concentration in the reaction medium of 40 mM, catalyst loading of 7.85 $$ {\mathrm{kg}}_{{\mathrm{Nb}}_2{\mathrm{O}}_5} $$kg Nb 2 O 5 m^− 3, and pH 4, reaching a MB degradation of 98% and a COD reduction of 79% at 150 min. The high activity of the Nb₂O₅ monolith catalyst remained constant after 10 catalytic tests.

The term biorefinery is related to the sustainable production of value-added bioproducts and bioenergy from biomass. Esters from fatty acids are important compounds synthesized from by-products of the oleochemical industry. In agreement with the biorefinery concept, it is important to search for catalysts that reduce the consumption of energy and water, using moderate operation conditions and low reaction times. In this work, response surface methodology (RSM) was used to optimize the enzymatic synthesis of pentyl oleate using Candida antarctica lipase B (CALB) immobilized on a polyethylene-aluminum structured support. A factorial design was employed to evaluate the effects of several parameters on the ester yield. To obtain a model with a good fit, an approach to reaction mechanism and enzyme kinetics was taken into consideration. Experimental findings were correlated and explained using equations of a ping-pong bi-bi kinetic model and considering the inhibitory effects of both substrates. The developed model was consistent with the experimental data predicting an increase in pentyl oleate production with increasing temperature and a decrease with higher oleic acid amounts and alcohol to acid molar ratios. This model could be useful in a future industrial application of CALB/LLDPE/Al to minimize the costs in oleochemical biorefineries.