催化学报 ›› 2019, Vol. 40 ›› Issue (8): 1168-1177.DOI: 10.1016/S1872-2067(19)63371-1

• 论文 • 上一篇    下一篇

氧化铌高效催化生物质衍生物的羟醛缩合反应制备燃料前驱体

景亚轩, 辛宇, 郭勇, 刘晓晖, 王艳芹   

  1. 华东理工大学化学与分子工程学院, 工业催化研究所, 上海市功能材料化学重点实验室, 上海 200237
  • 收稿日期:2019-02-26 修回日期:2019-04-06 出版日期:2019-08-18 发布日期:2019-06-21
  • 通讯作者: 王艳芹, 郭勇
  • 基金资助:
    国家自然科学基金(21832002,21872050,21808063);中央高校基本科研业务费专项资金(222201718003);上海市自然科学基金(18ZR1408500,10dz2220500);华工理工大学“张江树优博”培育计划.

Highly efficient Nb2O5 catalyst for aldol condensation of biomass-derived carbonyl molecules to fuel precursors

Yaxuan Jing, Yu Xin, Yong Guo, Xiaohui Liu, Yanqin Wang   

  1. Shanghai Key Laboratory of Functional Materials Chemistry, Research Institute of Industrial Catalysis, School of Chemistry and Molecular Engineering, East China University of Science and Technology, Shanghai 200237, China
  • Received:2019-02-26 Revised:2019-04-06 Online:2019-08-18 Published:2019-06-21
  • Supported by:
    This work was financially supported by the National Natural Science Foundation of China (No. 21832002, 21872050, and 21808063), the Fundamental Research Funds for the Central Universities (222201718003), the Science and Technology Commission of Shanghai Municipality (18ZR1408500, 10dz2220500), and the "Zhang Jiangshu" Excellent Ph.D. Project of ECUST.

摘要: 生物质是自然界唯一可再生的有机碳来源,其催化转化制备燃料和精细化学品受到广泛关注.一般从生物质衍生的小分子出发制备航空煤油和柴油等高碳数燃料包括两步:首先通过碳链增长反应如羟醛缩合和烷基化等制备目标链结构的燃料前驱体,然后对所得燃料前驱体进行完全脱氧加氢得到燃料组分.在目前报道的碳链增长反应中,羟醛缩合反应应用最多,因为生物质衍生的羰基化合物众多,而且丙酮、糠醛及环己酮等羰基化合物已经实现了工业化生产.羟醛缩合反应的催化剂以碱性材料为主,但是碱性催化剂具有不抗二氧化碳、不抗水等缺点,因此开发高活性的固体酸催化剂至关重要.
本文选择糠醛和4-庚酮的羟醛缩合反应作为模型反应,发现氧化铌材料对该反应具有优异的催化活性,活性明显高于常见的氧化钙、氧化镁、镁铝水滑石等固体碱和氧化铝、氧化锆等固体酸.并采用N2吸附-脱附、二氧化碳程序升温脱附(CO-TPD)、吡啶吸附红外光谱(Py-FTIR)、程序升温氨脱附(NH3-TPD)和丙酮的原位吸附傅立叶变换红外光谱等表征手段研究了氧化铝,氧化锆和氧化铌催化性能差异的原因.结果表明,这三种催化剂的比表面积和酸性质与反应活性没有明显关联.为了解释反应活性的差异,我们采用丙酮原位吸附红外光谱探究了这三种催化剂对羰基的活化.发现相比于氧化铝和氧化锆催化剂,氧化铌对丙酮的C=O双键有更强的活化能力,使C=O双键结构更容易转化为烯醇式结构,进而促进羟醛缩合反应的进行.基于此,我们提出了氧化铌催化羟醛缩合的反应机理.另外,底物拓展实验发现,在其他生物质相关的羟醛缩合反应体系中,氧化铌催化依旧可以得到可观的收率.循环套用实验表明,由于积碳导致催化剂失活,通过简单的煅烧即可恢复活性.
我们之前的研究发现负载金属的铌基催化剂具有很好的断裂呋喃环上碳氧键的能力,是很好的脱氧加氢催化剂.基于以上研究和我们之前的结论,我们设计并制备了多功能的Pd/Nb2O5催化剂,对该催化剂进行了结构表征,并对羟醛缩合和脱氧加氢过程进行了设计整合,一锅实现了羟醛缩合和后续的脱氧加氢.

关键词: 羟醛缩合, 氧化铌, C=O活化, 燃料前驱体, 生物燃料, 一锅过程

Abstract: Aldol condensation is of significant importance for the production of fuel precursors from biomass-derived chemicals and has received increasing attention. Here we report a Nb2O5 catalyst with excellent activity and stability in the aldol condensation of biomass-derived carbonyl molecules. It is found that in the aldol condensation of furfural with 4-heptanone, Nb2O5 has obviously superior activity, which is not only better than that of other common solid acid catalysts (ZrO2 and Al2O3), more importantly, but also better than that of solid base catalysts (MgO, CaO, and magnesium-aluminum hydrotalcite). The detailed characterizations by N2 sorption/desorption, NH3-TPD, Py-FTIR and DRIFTS study of acetone adsorption reveal that Nb2O5 has a strong ability to activate the C=O bond in carbonyl molecules, which helps to generate a metal enolate intermediate and undergo the nucleophilic addition to form a new C-C bond. Furthermore, the applicability of Nb2O5 to aldol condensation is extended to other biomass-derived carbonyl molecules and high yields of target fuel precursors are obtained. Finally, a multifunctional Pd/Nb2O5 catalyst is prepared and successfully used in the one-pot synthesis of liquid alkanes from biomass-derived carbonyl molecules by combining the aldol condensation with the sequential hydrodeoxygenation.

Key words: Aldol condensation, Nb2O5, C=O activation, Fuel precursor, Bio-liquid alkane, One-pot process