Supported rhenium catalysts for the hydrogenation of levulinic acid derivatives: limits and potential

Abstract

Levulinic acid derivatives, such as alkyl levulinates, are suitable starting reactants for the production of fuel components, namely γ-valerolactone (GVL), alkyl valerates, pentanol, and pentylvalerate (PV). The reactions were performed...

Efficient hydrodeoxygenation of methyl levulinate into pentanoic biofuels over Ru/USY catalysts

“…Similar to the tendency of the acid concentrations of different Ru/USY catalysts, a gradual decrease in the overall amount of Al IV , Al V and Al VI species can be observed with increasing Si/Al ratio, further confirming the decrease in the quantity and strength of acid sites of Ru/USY catalysts. Additionally, the 27 Al MAS NMR spectrum of the spent Ru/ USY-15 catalyst after six consecutive runs shows a similar pattern to the fresh Ru/USY-15 catalyst (Fig. S6 †), further indicating the limited dealumination and validating the good stability of the Ru/USY-15 catalyst.…”

“…As shown in Fig. 4a, the 27 Al MAS NMR spectra of Ru/USY catalysts show three resonances (Al IV , Al V and Al VI ). In detail, the Al IV resonance, possessing an isotropic shift of around 57 ppm, is assigned to the tetrahedral framework aluminium (FAl) species.…”

“…With increasing Si/Al ratios, the amounts of weak and strong acid both gradually decreased, and reduced to 160 and 100 µmol g −1 for the Ru/USY-40 catalyst, respectively. As a powerful tool to differentiate Al speciation in zeolites, 27 Al MAS NMR was employed to analyse the four Ru/USY catalysts. As shown in Fig.…”

“…[15][16][17][18][19][20][21][22][23][24][25] To alleviate the severity of the reaction medium for catalysts, alkyl levulinate, instead of LA, has been used as the benign substrate, which can be applied with a high substrate concentration up to a neat substrate for the efficient production of pentanoic biofuels. 26,27 Still, the optimal ratio balance between metal and acid functions with the zeolite-confined metal-acid intimacy is rarely reported for the efficient HDO of LA or alkyl levulinate into PA/PEs. Herein, four distinct 1 wt% Ru/USY catalysts with different Si/ Al ratios, possessing confined site proximity, have been successfully prepared via an improved impregnation method.…”

“…In addition, no apparent drop in the catalytic performance of Ru/ USY-15 has been evidenced upon six consecutive runs, indicating the good stability of Ru/USY-15. By a combination of scanning transmission electron microscopy (STEM), temperature-programmed desorption of ammonia (NH 3 -TPD), solid-state 27 Al magic angle spinning nuclear magnetic resonance ( 27 Al MAS NMR) spectroscopy and Fourier transform infrared spectroscopy (FT-IR) studies using CO as a probe molecule, an optimal site balance with a metal/strong acid ratio of 0.19 (ca. 1 : 5) can be depicted for the excellent performance of Ru/USY-15.…”