An effective and sustainable process capable of simultaneously execute desulfurization and denitrogenation of fuels is in fact an actual necessity in the refinery industry. The key to achieve this goal is the parallel oxidation of sulfur and nitrogen compounds present in fuels, which is only achieved by an active and recovered catalyst. A novel heterogeneous catalyst was successfully prepared by the encapsulation of an imidazolium-based polyoxometalate (POM) into a ZIF-8 framework ([BMIM]PMo12@ZIF-8). This composite material revealed exceptional catalytic efficiency to concurrently proceed with the oxidative desulfurization and denitrogenation of a multicomponent model fuel containing various sulfur and nitrogen compounds. A complete removal of all these compounds was achieved after only one hour and the catalyst system was able to be reused for ten consecutive cycles without loss of efficiency. In fact, an ionic liquid POM was incorporated in the ZIF-8 for the first time, and this composite compound was originally applied as a catalyst for simultaneous oxidative desulfurization and denitrogenation processes.

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Biodiesel is one of the most significant and valuable alternatives to fossil fuels. In the process of transesterification to produce biodiesel from various feedstocks, glycerol is one of the side products obtained, in a high glycerol: biodiesel weight ratio (1:10). Therefore, the growing world demand for biodiesel prompted a glycerol surplus. It is, thus, of interest to find new and added-value paths for the transformation of this abundant chemical. One of the most auspicious glycerol applications is the production of fuel additives, namely cyclic acetals and ketals, from aldehydes and ketones, respectively. In this work, coordination polymers based on nitrile (trimethylphosphonic acid) and Ln3+/Eu3+ are used as catalysts for the acetalization of the bio-renewable glycerol into oxygenated fuel additives. Solketal is the major product obtained from the reaction of glycerol with acetone. This product improves the cold flow properties, lowering the viscosity of biodiesel, improving combustion, and boosting the octane number. The stability of the materials is studied as well as their recovery and reuse.

Four lignocellulosic materials (walnut shell, chestnut shell, pine wood and burnt pine wood) were analyzed as biosorbents to remove nickel ions in aqueous solution. The optimal pH condition was determined. Due to this, a range of different pHs (3.0 to 7.5) was tested. The adsorption isotherms and kinetics were established. To plot Langmuir and Freundlich isotherms, batch adsorption tests were made with variable nickel concentrations (5 to 200 mg L−1). The pseudo-first order, pseudo-second order, Elovich and intraparticle diffusion models were used to describe the kinetics, batch adsorption tests were carried out with 25 mg L−1 of nickel solution and agitation time varied from 10 to 1440 min. The specific surface area of the different materials was between 3.97 and 4.85 m2g−1 with the exception for wood with 1.74 m2g−1. The pore size was 26.54 nm for wood and varied between 5.40 and 7.33 nm for the remaining materials. The diffractograms analysis showed that all the lignocellulosic materials presented some crystalline domains with the exception of burnt pine wood which was completely amorphous. The best pH was found to be around 5.0. At this pH the adsorption was higher for chestnut shells, walnut shells, burnt pine wood and wood, respectively. All samples fitted the Langmuir model well, with R2 of 0.994 to 0.998. The sorption kinetics was well described by the pseudo-second order equation with R2 between 0.996 and 1.00. No significative differences on the surface of the materials before and after adsorption could be observed by SEM. Finally, all materials tested were able to remove nickel ions in aqueous solution.