Hydrogenation and hydrodeoxygenation of difurfurylidene acetone to liquid alkanes over Raney Ni and the supported Pt catalysts

Abstract

Direct HDO process for difurfurylidene acetone dimer (F2A) conversion to liquid alkanes (C8C14) at 260°C in a batch reactor was investigated over different material supported 1wt%Pt catalysts, including SAPO-11, HZSM-5, SiO2Al2O3, MCM-22, and home-made SiO2ZrO2. C8C14 alkanes of 55.8% was obtained over the optimized 1wt%Pt/SiO2ZrO2 due to its proper pore size of 9.0nm and moderate acidic centers, together with more than 10% carbon yield of the oxygenated hydrocarbons, including C11C13 chain alcohols & ketones and the hydrogenated F2A dimers with furan ring (H-F2A dimers). To improve the liquid alkane yield, a two-step process for F2A conversion was also investigated, which included low-temperature hydrogenation at 50°C over Raney Ni catalyst in a batch reactor and the subsequent high-temperature hydrodeoxygenation (HDO) at 280°C over 1wt%Pt/SiO2ZrO2 in a fixed-bed reactor. The selectivity of 1,5-di(tetrahydro-2-furanyl)-3-pentanol (II-c) was the highest of 83.0% among the hydrogenated intermediates of H-F2A dimers due to the protonation effect of methanol as the solvent and the hydrogenation of CC bonds by Ni active centers. In the same time, the high content of this saturated alcohol H-dimer of II-C increased the solubility and stability of the intermediates in methanol solvent. High carbon yield of C8C14 alkanes of 82.9%(mol) was obtained after oxygen atom removal from H-F2A dimers via. the second-step HDO reaction. Long time operation showed the stability of 1wt%Pt/SiO2ZrO2 as HDO catalyst, deduced from the steady phase structure, acidity of SiO2ZrO2 support and Pt active centers by catalyst characterization.