Heterogeneous hydroconversion of levulinic acid over silica-supported Ni catalyst
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Silica-supported Ni catalyst (6.6 wt% Ni) was prepared and tested in solvent-free hydroconversion of levulinic acid (LA) using flow-through fixed-bed tube-type microreactor at 250 and 275 °C in the pressure and space time range of 1–30 bar and 0.1–1.0 gcat g LA −1 h, respectively. The catalyst was characterized by XRD, adsorption/desorption N2 isotherms, temperature-programmed H2-reduction (H2-TPR), FT-IR spectra of adsorbed pyridine (Py), and temperature-programmed H2 desorption (H2-TPD). At 250 °C and 1 bar total pressure LA was dehydrated to α-angelica lactone (AL) intermediate that was hydrogenated to γ-valerolactone (GVL). At space time 0.25 gcat g LA −1 h 82% GVL selectivity was achieved at virtually full LA conversion. The GVL became partially converted to pentanoic acid (PA). At longer space time, 1.0 gcat g LA −1 h, the PA selectivity increased to 37%. At pressure > 1 bar the favored reaction of GVL was the hydrogenolysis of its ester bond and dehydration of the intermediate 1,4-pentanediol (1,4-PD) to 2-methyltetrahydrofuran (2-MTHF). At 250 °C and 30 bar the yield of 2-MTHF was 56 mol%. The product distribution is controlled by the relative activity of the Ni/SiO2 catalyst in the hydrogenolysis of the GVL C–O bonds.
KeywordsLevulinic acid hydroconversion Ni/SiO2 catalyst γ-valerolactone hydrogenolysis 2-Methyltetrahydrofuran Pentanoic Acid
The authors acknowledge the financial support of the project of the Economic Development and Innovation Operative Program of Hungary, GINOP-2.3.2-15-2016-00053: Development of liquid fuels having high hydrogen content in the molecule (contribution to sustainable mobility). The Project is supported by the European Union. Thanks are also due to the Indo-Hungarian project entitled “Biochemicals and biofuels from lignocellulosic biomass by Green catalytic processes” (Grant No. TÉT_15_IN-1-2016-0034) and the Argentine-Hungarian project entitled “Development of catalytic processes for the agro-environmental protection and agro technology” (Grant No. TÉT_15-1-2016-0089) financed by the National Research, Development and Innovation Office of Hungary. Further thanks is due to COST Action FP1306 (LIGNOVAL).
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