催化学报 ›› 2020, Vol. 41 ›› Issue (3): 404-414.DOI: 10.1016/S1872-2067(19)63505-9

• 论文 • 上一篇    下一篇

Cu/SBA-15-SO3H催化木糖一锅转化制备糠醇

邓天宇, 许光月, 傅尧   

  1. 中国科学技术大学化学与材料科学学院, 合肥微尺度物质科学国家实验室, iChEM(能源材料化学协同创新中心), 安徽省生物质洁净能源重点实验室, 安徽合肥 230026
  • 收稿日期:2019-07-27 修回日期:2019-08-29 出版日期:2020-03-18 发布日期:2019-11-19
  • 通讯作者: 傅尧
  • 基金资助:
    国家重点研发计划(2018YFB1501600);国家自然科学基金(21572212,51821006,51961135104);安徽省科技重大专项(18030701157);中国科学院战略性先导科技专项(CAS(XDA21060101));广东珠江人才计划地方创新研究团队项目(2017BT01N092).

One-pot cascade conversion of xylose to furfuryl alcohol over a bifunctional Cu/SBA-15-SO3H catalyst

Tianyu Deng, Guangyue Xu, Yao Fu   

  1. Hefei National Laboratory for Physical Sciences at the Microscale, iChEM, CAS Key Laboratory of Urban Pollutant Conversion, Anhui Province Key Laboratory of Biomass Clean Energy, University of Science and Technology of China, Hefei 230026, Anhui, China
  • Received:2019-07-27 Revised:2019-08-29 Online:2020-03-18 Published:2019-11-19
  • Supported by:
    This work was supported by the National Key R&D Program of China (2018YFB1501600), the National Natural Science Foundation of China (21572212, 51821006, 51961135104), the Major Science and Technology Projects of Anhui Province (18030701157), the Strategic Priority Research Program of Chinese Academy of Sciences (XDA21060101), and the Local Innovative and Research Teams Project of Guangdong Pearl River Talents Program (2017BT01N092). The authors thank the Hefei Leaf Co., Ltd. for free samples that helped us conduct this study.

摘要: 糠醇是一种重要的高附加值化学品,目前工业上由含半纤维素或木聚糖的生物质原料经过酸脱水先制备糠醛,糠醛再进一步加氢制备糠醇.在实际生产中,这两步反应分别在不同的设备中进行,增加了分离纯化和运输成本目前也很少有研究偶联这两步反应.本工作中,我们制备了一种多功能介孔Cu/SBA-15-SO3H催化剂用于一锅法一步转化木糖到糠醛,并且通过X射线粉末衍射(XRD)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)、热重分析(TGA)、电感耦合等离子体发射光谱(ICP-OES)、X射线荧光(XRF)、NH3-程序升温脱附(NH3-TPD)和N2物理吸附等表征检测了负载的酸和金属位点的可用性以及催化剂的物理化学性质,优化了反应温度、氢气压力、反应时间和溶剂体系等反应条件,研究了酸和金属位点的比例以及介孔尺寸对合成糠醇的影响.
XRD表征和TEM及HRTEM图像均表明,在负载了磺酸和Cu之后,均会一定程度上破坏SBA-15的形貌,但是依然可以保持原本的有序介孔结构.XPS表明还原后的Cu主要以+1价的形式存在,也有少量的0价和+2价.红外光谱表明磺酸基团和SBA-15载体以共价键形式紧密结合.氮气吸脱附和相关的BET和BJH计算表明,我们的原位制备方法相比于传统浸渍法,磺酸位点的含量提高了7倍以上.
通过对反应条件的优化,该体系在140℃和4 MPa H2下可以实现62.6%的糠醇收率.过高的温度会引起产物过度加氢生成2-甲基呋喃,而过高的压力会导致原料过度加氢生成木糖醇.合适的溶剂也是反应的关键因素,使用1:3的水/丁醇双相体系,一方面可以有效促进糖的溶解,另一方面可以有效萃取产物,保证了反应的碳平衡.
在对催化剂的筛选中发现,单独的SBA-15几乎无催化活性,Cu/SBA-15主要催化木糖加氢生成木糖醇,SBA-15-SO3H主要催化木糖脱水生成糠醛,而物理混合的Cu/SBA-15和SBA-15-SO3H的效率远不如双功能Cu/SBA-15-SO3H催化剂.通过调节磺酸含量和探究产物时间曲线发现,提高酸性位点可以促进木糖转化,但是过多的酸性位点会导致结焦,降低糠醇收率.共同存在的磺酸酸性位点和铜金属位点保持平衡,协同催化串联反应进行.通过调节SBA-15的孔道结构发现,4nm的孔道最适合反应进行,孔道过大会降低反应的整体碳收率和糠醇收率.
本催化体系实现了从木糖一锅多步法制糠醇,并对催化剂的构效关系进行了研究,对反应条件进行了系统的优化,有希望实际应用到糠醇生产中.

 

关键词: 生物质, 糠醇, 多相催化, 一锅法合成, 木糖

Abstract: The conversion of hemicellulose-derived xylose to furfuryl alcohol is a practical procedure for producing value-added chemicals from biomass. In this study, a bifunctional Cu/SBA-15-SO3H catalyst was employed for the one-pot catalytic conversion of xylose to furfuryl alcohol with a yield of up to 62.6% at the optimized conditions of 140℃, 4 MPa, and for 6 h in a biphasic water/n-butanol solvent. A high reaction temperature resulted in further hydrogenation to 2-methyl furan, while a high hydrogen pressure led to a side hydrogenation reaction to xylitol. The biphasic solvent allowed xylose solvation as well as furfuryl product extraction. The acidic -SO3H sites and Cu sites co-existed, maintained a balance, and cooperatively catalyzed the cascade conversion. Excessive acidic sites and large pores could promote the xylose conversion, although a low furfuryl alcohol yield was obtained. This catalytic system could be potentially applied to the one-pot synthesis of furfuryl alcohol from hemicellulose-derived xylose.

Key words: Biomass, Furfuryl alcohol, Heterogeneous catalysis, One-pot synthesis, Xylose

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