LAUSR

Partial hydrogenolysis of erythritol, which can be produced in large scale by fermentation, to 1,4-butanediol (1,4-BuD) was investigated with Ir-ReOx/SiO2 and Ir-ReOx/rutile-TiO2 catalysts (4 wt% Ir). In addition to the higher conversion rate over Ir-ReOx/TiO2 than over Ir-ReOx/SiO2 which has been also reported in glycerol hydrogenolysis, Ir-ReOx/TiO2 catalyst showed higher selectivity to 1,4-BuD than Ir-ReOx/SiO2 especially at low conversion levels, leading to high productivity of 1,4-BuD: 20 mmol1,4-BuD gIr-1 h-1 at 373 K (36% conversion, 33% selectivity). The productivity based on noble metal amount is higher than those reported in the literature, although the maximum yield of 1,4-BuD (23%) is not higher than the highest ones in the literature. The reactions of various triols, diols and mono-ols were tested and the selectivity and the reaction rates were compared between catalysts and between substrates. The Ir-ReOx/TiO2 catalyst showed about two-fold higher activity than Ir-ReOx/SiO2 in hydrogenolysis of C-OH bond at 2- or 3-positions in 1,2- and 1,3-diols, respectively, while the hydrogenolysis of C-OH bond at the 1-position is less promoted by TiO2 support. Lowering the loading amount of Ir on TiO2 (from 4 wt% to 2 or 1 wt%) decreased the Ir-based activity and 1,4-BuD selectivity. Similarly, increasing the loading amount on SiO2 from 4 wt% to 20 wt% increased the Ir-based activity and 1,4-BuD selectivity, although they were still lower than those of TiO2-supported catalyst with 4 wt% Ir. The high concentration of loaded metals on support is important.