碱催化促进Ni-W/β分子筛催化剂氢解纤维素产1,2-丙二醇的研究

为提高纤维素催化氢解产醇类产物中1,2-丙二醇(1,2-PG)的收率,采用等体积浸渍法制备了以β分子筛为载体负载Ni和W的催化剂。结果表明,当7Ni-20W/β分子筛作为催化剂时,在240℃反应温度和6.0 MPa H_2的条件下反应30 min后,纤维素实现完全转化,1,2-PG和乙二醇(EG)产率分别达到19.3%和45.3%;不同于其他载体催化剂,β分子筛可以明显提高1,2-PG选择性。当不同碱催化剂加入到Ni-W/β分子筛催化剂反应体系后,可以进一步提高1,2-PG的选择性。尤其是当加入Ba(OH)_2后,1,2-丙二醇产率从19.3%提高了32.5%。为了探究碱催化剂在反应中的作用,以葡萄糖为底物进行了一系列的碱催化反应。结果表明,碱催化剂主要作用是有助于将葡萄糖异构化为果糖,从而促进纤维素转化为1,2-PG。催化剂在两次回收重复利用之后1,2-PG的收率只下降3.9%,乙二醇产率收率下降4.1%。

Study on the synthesis of propylene glycol through cellulose hydrogenation using alkaline promoted Ni-W/β-zeolite catalysts

A series of Ni-W/β zeolite catalysts were prepared via incipient impregnation method in order to improve the yield of 1,2-propylene glycol (1,2-PG) in the alcohol products of cellulose hydrogenation. Under the reaction conditions of 240℃ and 6.0 MPa H₂ for 30 min, the complete conversion of cellulose was obtained and the yields of 1,2 propylene glycol and ethylene glycol (EG) were 19.3% and 45.3%, respectively. Different from other supports, the selectivity of 1,2-PG was highly improved when β zeolite was used. The selectivity of 1,2-PG was further improved after the addition of alkaline, and the yield of 1,2-PG was up to 32.5% especially for Ba(OH)₂. The function of alkaline catalysts in the reaction was also discussed based on a series of reactions using glucose as the substrate, indicating that alkaline was favorable for the isomerization of glucose to fructose and thus promoted the conversion of cellulose into 1,2-PG. After two cycles of reuse, the yield of 1,2-PG and EG slightly decreased (3.9% and 4.1%, respectively).