Conversão de furfural sobre zeólitas (Hf, Al)-ZSM-5 hierárquicas: controle da relação de sítios ácidos de Lewis e Brønsted e seu efeito na seletividade a produtos ; Furfural conversion over hierarchical (Hf, Al)-ZSM-5 zeolites: control of Lewis and Brønsted acid sites and their effect on selectivity to products

One-pot catalytic processes using heterogeneous acid catalysts have been a promising strategy for the valorization of platform molecules from lignocellulosic biomass, such as the transformation of furfural (Fur) to γ-valerolactone (GVL), levulinic acid (AL), levulinate esters, angelic lactones, etc., which can be used for the production of biofuels and additives, "green" solvents and chemical intermediates. Among the catalysts used in these processes, zeolites with Lewis acidity (L) and Brønsted (B) have demonstrated remarkable activities for coupling reactions by Meerwein Ponndorf-Verley transfer hydrogenation (MPV), hydrolysis/ alcoholysis and lactonization, which are routes of synthesis used in the conversion of molecules derived from lignocellulosic biomass. However, in the conversion of Fu, there are still limitations to be overcome, such as the development of more selective heterogeneous catalysts and with more active and accessible sites capable of performing the stages of hydrogenation by MPV and hydrolysis/alcoholysis. For MPV transfer hydrogenation reactions, zeolites with incorporated tetravalent metals (Ti, Sn, Zr, and Hf) have shown high activities, with those Hf-incorporated being the most active. In this context, this work proposes to develop hierarchical ZSM-5 zeolites containing L acid sites generated by Hf and B acid sites to be used as catalysts for the conversion of Fur in the presence of 2-propanol to more valuable products. For this purpose, hierarchical ZSM-5 zeolites with acidity of L and B were prepared by post-synthesis strategies of desilication, dealumination, and incorporation in liquid phase of Hf4+ cations. Analyses from XRD, DRS-UV-Vis, N2 physisorption, and FTIR in situ with adsorbed pyridine proved that the synthesis methods employed are capable to obtain micro-mesoporous ZSM-5 zeolites with both types of acid sites. In the catalytic tests, the hierarchical zeolites were able to catalyze the Fur conversion by in series reactions, generating mainly products such as GVL, AL, ...