Acta Chim. Sinica ›› 2017, Vol. 75 ›› Issue (5): 439-447.DOI: 10.6023/A17020061 Previous Articles     Next Articles

Review

金属氧化物催化生物质衍生羧酸酮基化研究进展

丁爽, 葛庆峰, 祝新利   

  1. 天津大学化工学院 天津化学化工协同创新中心 天津 300072
  • 收稿日期:2017-02-16 出版日期:2017-05-15 发布日期:2017-04-12
  • 通讯作者: 祝新利 E-mail:xinlizhu@tju.edu.cn
  • 基金资助:

    项目受国家自然科学基金(Nos.21676194和21373148)和教育部新世纪优秀人才支持计划(NCET-12-0407)资助.

Research Progress in Ketonization of Biomass-derived Carboxylic Acids over Metal Oxides

Ding Shuang, Ge Qingfeng, Zhu Xinli   

  1. Collaborative Innovation Center of Chemical Science and Engineering, School of Chemical Engineering and Technology, Tianjin University, Tianjin 300072, China
  • Received:2017-02-16 Online:2017-05-15 Published:2017-04-12
  • Contact: 10.6023/A17020061 E-mail:xinlizhu@tju.edu.cn
  • Supported by:

    Project supported by the National Natural Science Foundation of China (Grant Nos. 21676194 and 21373148) and the Ministry of Education of China Program of New Century Excellent Talents in University (Grant No. NCET-12-0407).

With the increasing needs for transportable fuels and the growing concerns on environmental pollution, significant attention has been paid to the conversion of renewable lignocellulosic biomass to liquid fuels. As a major component of bio-oil from biomass depolymerization, organic carboxylic acids make the bio-oil acidic, corrosive and unstable, which are harmful for storage, transportation, and upgrading of bio-oil. Therefore, the removal of carboxylic acids is very important. Ketonization reaction, also called ketonic decarboxylation, converts two moles carboxylic acids to ketone (symmetrical or asymmetrical ketones), carbon dioxide and water, which removes oxygen efficiently and increases the carbon chain length without using hydrogen. In addition, ketones are important chemicals and have been widely used in chemical industry as organic solvent. The mechanism and active site for ketonization are still under debate. Various mechanisms have been proposed for the ketonization, based on different reaction intermediates evolved (i.e., β-keto-acids, ketene, carboxylates and acyl carbonium ions). Ketonization reaction is a surface-structure-sensitive reaction, thus reaction activity depends on surface-structure of the metal oxides (such as crystal surfaces and particle size). The concerted function of oxygen anions (Brønsted bases) and unsaturated metal cations (Lewis acids) is crucial for ketonization. The amphoteric oxides show better catalytic activity than pure acidic or basic oxides. Oxygen vacancy formed on the surface of metal oxides is a key factor for high ketonization activity, which can stabilize the reaction product and reduce the activation energy. This paper reviews the progress in ketonization from the aspects of reaction mechanism, and the effects of surface structure, acidity and basicity, and reducibility of metal oxides on ketonization. The β-keto-acids based mechanism and ketene based mechanism will be discussed in detail to understand how does the C—C coupling happen and the fundamental role of α-H. Finally, the importance of surface structure and properties of metal oxides on the carboxylic acids ketonization reaction is explained.

Key words: carboxylic acid, ketonization, metal oxides, surface-structure and property, reaction mechanism