Selective Hydrogenolysis of Erythritol over Ir−ReO<sub><i>x</i></sub>/Rutile‐TiO<sub>2</sub> Catalyst
Minyan Gu, Lujie Liu, Yoshinao Nakagawa, Congcong Li, Masazumi Tamura, Zheng Shen, Xuefei Zhou, Yalei Zhang, Keiichi Tomishige
Abstract
Abstract Partial hydrogenolysis of erythritol, which can be produced at large scale by fermentation, to 1,4‐butanediol (1,4‐BuD) is investigated with Ir−ReO x /SiO 2 and Ir−ReO x /rutile‐TiO 2 catalysts. In addition to the higher conversion rate over Ir−ReO x /TiO 2 than over Ir−ReO x /SiO 2 , which has been also reported for glycerol hydrogenolysis, Ir−ReO x /TiO 2 showed higher selectivity to 1,4‐BuD than Ir−ReO x /SiO 2 , especially at low conversion levels, leading to high 1,4‐BuD productivity of 20 mmol 1,4‐BuD g Ir −1 h −1 at 373 K (36 % conversion, 33 % selectivity). The productivity based on the noble metal amount is higher than those reported previously, although the maximum yield of 1,4‐BuD (23 %) is not higher than the highest reported values. The reactions of various triols, diols and mono‐ols are tested and the selectivity and the reaction rates are compared between catalysts and between substrates. The Ir−ReO x /TiO 2 catalyst showed about twofold higher activity than Ir−ReO x /SiO 2 in hydrogenolysis of the C−OH bond at the 2‐ or 3‐positions in 1,2‐ and 1,3‐diols, respectively, whereas the hydrogenolysis of C−OH at the 1‐position is less promoted by the TiO 2 support. Lowering the loading amount of Ir on TiO 2 (from 4 wt % to 2 or 1 wt %) decreases the Ir‐based activity and 1,4‐BuD selectivity. Similarly, increasing the loading amount on SiO 2 from 4 wt % to 20 wt % increases the Ir‐based activity and 1,4‐BuD selectivity, although they remain lower than those for TiO 2 ‐supported catalyst with 4 wt % Ir. High metal loadings on the support seem to be important.