Zeolite-catalyzed isomerization of triose sugars.
Zeolite-catalyzed isomerization of triose sugars.
复制标题
DOI：
10.1002/cssc.200900099
复制
发表时间：
2009-07
期刊：
影响因子：
8.4
通讯作者：
Esben Taarning;S. Saravanamurugan;M. Holm;Jianmin Xiong;R. West;C. Christensen
中科院分区：
文献类型：
--
作者：
Esben Taarning;S. Saravanamurugan;M. Holm;Jianmin Xiong;R. West;C. Christensen
乳酸是一种重要的化学物质，用于生产可生物降解的聚合物和溶剂。乳酸的工业生产是以微生物发酵葡萄糖和蔗糖的厌氧发酵为基础的与此过程相关的主要并发症是在发酵过程中需要用化学计量量的碱中和乳酸，以及从水发酵液中产生乳酸的能量密集型工作。然而，基于三糖二羟基丙酮（DHA）和甘油醛（GLA）的异构化，可以设想一种不同的乳酸生成途径。该工艺可以以甘油为原料，分别通过发酵[3]和催化氧化[3]转化为GLA和DHA。本文中，我们报道了路易斯酸沸石，如sn - β，在三糖异构化成乳酸和异构化-酯化成乳酸酯方面表现出惊人的高活性和选择性。这一发现代表了一种最具选择性的沸石催化的生物质底物转化。此外，我们证明了Lewis酸和Brønsted酸对产物选择性的重要作用，并提出异构化反应涉及仅由Lewis酸催化的Meerwein-Ponndorf-Verley还原和Oppenauer氧化（MPVO）型氧化还原步骤。
Lactic acid is an important chemical that is used for production of biodegradable polymers and solvents. The industrial production of lactic acid is based on the anaerobic fermentation of glucose and sucrose using microbial fermentation.[1] The major complications associated with this process are the need to neutralize lactic acid with a stoichiometric amount of base during the fermentation process and the energy-intensive work-up of lactic acid from the aqueous fermentation broth. However, a different route to lactic acid, based on the isomerization of the triose sugars dihydroxyacetone (DHA) and glyceraldehyde (GLA), could be envisioned. Such a process could be based on glycerol as a raw material, which can be converted to GLA and DHA by fermentation [2] or catalytic oxidation,[3] respectively.Herein, we report that Lewis-acidic zeolites such as Sn-Beta show surprisingly high activities and selectivities for the isomerization of trioses to lactic acid, and for the isomerization–esterification to form lactate esters. This discovery represents one of the most selective zeolite-catalyzed transformations of a biomass substrate. Furthermore, we demonstrate the important role that Lewis and Brønsted acidity have on the product selectivity and we propose that the isomerization reaction involves a Meerwein–Ponndorf–Verley reduction and Oppenauer oxidation (MPVO)-type redox step that is catalyzed only by Lewis acids.