Conversion of sugars to ethylene glycol with nickel tungsten carbide in a fed-batch reactor: high productivity and reaction network elucidation
作者:Roselinde Ooms、Michiel Dusselier、Jan A. Geboers、Beau Op de Beeck、Rick Verhaeven、Elena Gobechiya、Johan A. Martens、Andreas Redl、Bert F. Sels
DOI:10.1039/c3gc41431k
日期:——
Bifunctional nickel tungsten carbide catalysis was used for the conversion of aqueous sugar solutions into short-chain polyols such as ethylene glycol. It is shown that very concentrated sugar solutions, viz. up to 0.2 kg L−1, can be converted without loss of ethylene glycol selectivity by gradually feeding the sugar solution. Detailed investigation of the reaction network shows that, under the applied reaction conditions, glucose is converted via a retro-aldol reaction into glycol aldehyde, which is further transformed into ethylene glycol by hydrogenation. The main byproducts are sorbitol, erythritol, glycerol and 1,2-propanediol. They are formed through a series of unwanted side reactions including hydrogenation, isomerisation, hydrogenolysis and dehydration. Hydrogenolysis of sorbitol is only a minor source of ethylene glycol. To assess the relevance of the fed-batch system in biomass conversions, both the influence of the catalyst composition and the reactor setup parameters like temperature, pressure and glucose addition rate were optimized, culminating in ethylene glycol yields up to 66% and separately, volume productivities of nearly 300 gEG L−1 h−1.
双功能镍钨碳化物催化剂用于将水溶性糖溶液转化为乙二醇等短链多元醇。结果表明,通过逐渐加入糖溶液,可以转化非常高浓度的糖溶液(高达0.2 kg/L),而不会损失乙二醇的选择性。详细研究反应网络显示,在应用的反应条件下,葡萄糖通过逆醛醇反应转化为甘油醛,甘油醛进一步通过氢化反应转化为乙二醇。主要副产物是山梨醇、赤藓糖醇、甘油和1,2-丙二醇。它们是通过一系列不希望的副反应(包括氢化、异构化、氢解和脱水)形成的。山梨醇的氢解只是乙二醇的次要来源。为了评估批量进料系统在生物质转化中的相关性,优化了催化剂组成和反应器设置参数(如温度、压力和葡萄糖添加速率),最终乙二醇的收率高达66%,体积产率接近300 gEG/L/h。