One-pot synthesis of confined structure Ru3Sn7 alloy on alumina for an exceptionally rapid and selective hydrogenolysis furfuryl alcohol to 1,5-pentanediol

Abstract

A facile and one-pot synthesis for confined structure Ru3Sn7 alloy catalysts on Al2O3 for highly efficient and selective synthesis of 1,5-pentanediol (1,5-PeD) from furfuryl alcohol (FFalc) has been developed. Three types of Ru-Sn alloy catalysts were synthesised via three approaches; (i) a one-pot (op) method from ruthenium and tin salt solutions and Al(OH)3 hydrargillite-type at 150 oC for 24 h; (ii) coprecipitation-hydrothermal (cop) procedure and (iii) wet-impregnation (imp) ruthenium and tin salt solutions and Al2O3-500, followed by reduction with H2 at 400 oC for 2 h, and produced (op)Ru-(x)Sn@Al2O3, (cop)Ru-(1.30)@Al2O3-500, and (imp)Ru-(1.23)Sn@Al2O3-500 catalysts, respectively. This obviously allowed the highest yield of 1,5-PeD (97%) with the highest productivity of 1,5-PeD (3.67 mmol 1,5-PeD/gcat. min) from FFalc in water at 140 oC, 10 bar H2, and 3 h. In this kind of (op)Ru-(1.30)Sn@Al2O3 catalysts, the presence of Ru3Sn7 or Ru-SnOx can catalyse the partial hydrogenation of the furan ring of FFalc to form 4,5-dihydrofuranmethanol (4,5-DHFM) and acidic species of SnOx or Snn+ or acidic Al2O3 could serve for activating the C2-O for ring opening processes, while Ru0 works for the following hydrogenation, led to high yield of the final product 1,5-PeD. This is recorded as the first and the highest 1,5-PeD yield compared to the state-of-the-art catalysts in the hydrogenolysis of FFalc to diols under mild reaction conditions. Though catalytic performance of the recycled (op)Ru-(1.30)Sn@Al2O3 catalyst can be restored after the reactivation with H2 at 400 oC for 1 h, the low amount of recyclability of the catalyst remains as the main drawback. Therefore, systematic investigations to overcome the low recyclability of catalyst after repeated reactions are substantially necessary.