Examinando por Autor "Moreno, I."
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Ítem Catalytic hydrodeoxygenation of m-cresol over Ni2P/hierarchical ZSM-5(Elsevier B.V., 2018) Berenguer, A.; Bennett, J.A.; Hunns, J.; Moreno, I.; Coronado, J.M.; Lee, A.F.; Pizarro, P.; Wilson, K.; Serrano, D.P.Bifunctional catalysts comprising Ni2P supported over a hierarchical ZSM-5 zeolite (h-ZSM-5) were synthesized and applied to the hydrodeoxygenation (HDO) of m-cresol, a model pyrolysis bio-oil compound. Surface and bulk characterization of Ni2P/h-ZSM-5 catalysts by XRD, TEM, DRIFTS, TPR, porosimetry and propylamine temperature-programmed desorption reveal that Ni2P incorporation modifies the zeolite textural properties through pore blockage of the mesopores by phosphide nanoparticles, but has negligible impact of the micropore network. Ni2P nanoparticles introduce new, strong Lewis acid sites, whose density is proportional to the Ni2P loading, accompanied by new Brönsted acid sites attributed to the presence of P–OH moieties. Ni2P/h-ZSM-5 is ultraselective (97%) for m-cresol HDO to methylcyclohexane, significantly outperforming a reference Ni2P/SiO2 catalyst and highlighting the synergy between metal phosphide and solid acid support. m-Cresol conversion was proportional to Ni2P loading reaching 80 and 91% for 5 and 10 wt% Ni respectively. Turnover frequencies for m-cresol HDO are a strong function of Ni2P dispersion, evidencing structure sensitivity, with optimum activity observed for 4 nm particles.Ítem Insights on the acetic acid pretreatment of wheat straw: Changes induced in the biomass properties and benefits for the bio-oil production by pyrolysis(Elsevier B.V., 2023) Pagano, M.; Hernando, H.; Cueto, J.; Cruz, P.L.; Dufour, J.; Moreno, I.; Serrano, D.P.This work discloses how the pretreatment of wheat straw with acetic acid (AA) solutions modifies the biomass composition, strongly affecting the pyrolysis product distribution. AA in diluted solutions is a renewable and eco-friendly reagent, being also one of the main components of the pyrolysis bio-oil* (water-free basis). In comparison with water and diluted ammonia treatments, AA washing leads to a higher removal degree of alkali and alkaline-earth elements (AAEMs) from the biomass ash. In addition, the AA pretreatment reduces the content of char and gas precursors, as is the case of soluble lignin and extractives. Consequently, the bio-oil* yield is drastically increased up to ∼53 wt% during the pyrolysis of the AA washed wheat straw, being much higher than the value obtained for the raw biomass (∼35 wt%). Likewise, the bio-oil* composition is highly improved by the pretreatment with AA, dramatically increasing the concentration and yield of levoglucosan, which is a valuable precursor to produce both advanced biofuels and bio-based chemicals. In contrast, the opposite occurs during the pyrolysis of the extracted matter samples, recovered from the washing solutions, since its high content of AAEMs, lignin and extractives promotes the formation of char and gases in the detriment of the bio-oil fraction. Based on a preliminary technoeconomic analysis, it is concluded that pretreatment with AA solutions may improve significantly the economic performance of the wheat straw pyrolysis process. This is due to the increased incomes coming from the higher yield of both bio-oil* and levoglucosan that largely compensate the additional capital and fresh AA costs.Ítem Tailoring the properties of hierarchical TS-1 zeolite synthesized from silanized protozeolitic units(2012) Serrano, D. P.; Sanz, R.; Pizarro, P.; Moreno, I.; ELSEVIERHierarchical TS-1 zeolites, characterized by having a secondary porosity within the supermicro/mesopore region (1.5-6 nm), have been synthesized following a procedure based on the silanization of protozeolitic units, which are previously generated by means of a precrystallization step. The silanization agent, phenylaminopropyltrimethoxysilane (PHAPTMS) acts as crystal growth inhibitor, hindering partially the protozeolitic units growth and aggregation during the crystallization treatment. Both the duration of the precrystallization step and the proportion of the organosilane compound added to the synthesis gel have a significant influence on the physicochemical and textural properties of the resultant materials. Thus, the best precrystallization time, leading to the most enhanced textural properties, is comprised between 22-24 hours. Using this time an appropriate balance between the number of protozeolitic units formed and their size is reached. On the other hand, by controlling the organosilane compound proportion added to synthesis gel, the contribution of the secondary porosity can be tailored. Likewise, amounts of organosilane larger than 5 mol% provide to a secondary porous system more uniform in size. The catalytic activity of these materials was evaluated in 1-octene and cyclohexene epoxidation reactions, using tert-butylhydroperoxide (TBHP) as oxidant. The olefin conversion and TOF values reached by hierarchical TS-1 zeolites are remarkably superior to that obtained with the conventional microporous TS-1 zeolite, being higher when the modification degree of the textural properties is more pronounced. These results can be ascribed to the higher accessibility of both TBHP and olefin to the titanium active sites located in the secondary porous system. Likewise, these zeolites exhibit a high oxidant efficiency and total selectivity to epoxide, parameters which are not affected by the presence of the secondary porosity.