CIESC Journal ›› 2021, Vol. 72 ›› Issue (6): 3084-3094.DOI: 10.11949/0438-1157.20201682

• Special column for comprehensive utilization of salt lake resouces in Qinghai • Previous Articles     Next Articles

Preparation and property of high specific surface solid base catalyst based on LiAl-LDH /C hybrid precursor

SONG Yihui1(),LEI Zhiyi2,FAN Guoli1(),YANG Lan1,LIN Yanjun1,3(),LI Feng1   

  1. 1.State Key Laboratory of Chemical Resource Engineering, Beijing University of Chemical Technology, Beijing 100029, China
    2.School of International Culture and Communication, Beijing City University, Beijing 100083, China
    3.College of Chemical Engineering, Qinghai University, Xining 810016, Qinghai, China
  • Received:2020-11-25 Revised:2021-02-19 Online:2021-06-05 Published:2021-06-05
  • Contact: FAN Guoli,LIN Yanjun

基于LiAl-LDH/C杂化前体制备高比表面固体碱催化剂及其催化性能研究

宋奕慧1(),雷志轶2,范国利1(),杨兰1,林彦军1,3(),李峰1   

  1. 1.北京化工大学化工资源有效利用国家重点实验室,北京 100029
    2.北京城市学院国际文化与传播学部,北京 100083
    3.青海大学化工学院,青海 西宁 810016
  • 通讯作者: 范国利,林彦军
  • 作者简介:宋奕慧(1995—),女,硕士研究生,yihuisong_951206@163.com
  • 基金资助:
    国家自然科学基金项目(21991102)

Abstract:

A series of LiAl-CO3-LDH/C hybrid composite precursors were prepared by a novel separate nucleation and aging steps we developed previously, glucose molecules were introduced as carbon source during the crystallization process of LDHs nuclei to fabricate LDHs/C hybrid composite precursor with controlled composition and structure. LiAl composite oxide based solid base catalyst with high specific surface area was obtained by topological transformation of precursors and removal of amorphous carbon components under high temperature treatment. Using XRD, FT-IR, BET, TEM, SEM, CO2-TPD and other characterization methods, the composition, structure, texture properties and surface basicity of the catalyst were studied in detail. Knoevenagel condensation reaction of benzaldehyde and ethyl cyanoacetate was used as the probe reaction to investigate the alkali catalytic performance of the prepared catalyst. The results indicate that molar ratio of glucose to Al3+, hydrothermal temperature and calcination temperature are the main factors affecting the activity of catalysts, and higher hydrothermal temperature or calcination temperature has negative impact on the exposure of basic sites. The LiAl-MMO-150-3-500 catalyst, calcinated at 500℃ with the molar ratio of glucose to Al3+ was 3 in the corresponding precursor, has a surface area of about 229 m2·g-1, the total basic sites of about 855 μmol·g-1 based on phenol adsorption method, and thus exhibits the highest catalytic performance with the conversion of benzaldehyde reach up to 88.21% under our experimental conditions.

Key words: layered double hydroxides, hybrid precursor, high specific surface areas, solid base catalyst, Knoevenagel condensation reaction

摘要:

采用成核-晶化隔离法制备LiAl-CO3-LDHs晶核,在LDHs晶核晶化的过程中引入葡萄糖分子作为碳源,构筑组成和结构可调的LDHs/C型杂化复合前体。通过高温处理,实现前体的结构拓扑转变及无定形碳组分的去除,得到高比表面积的LiAl复合金属氧化物型固体碱催化剂。采用XRD、FT-IR、BET、TEM、SEM、CO2-TPD等表征手段对催化剂的组成、结构、织构性能、表面碱性进行了详细研究,并以苯甲醛和氰基乙酸乙酯间的Knoevenagel缩合反应为探针反应系统地研究了催化剂的碱催化性能。研究结果表明,LDHs/C杂化前体制备过程中葡萄糖与金属离子的摩尔比、水热晶化温度以及焙烧温度是影响催化剂活性的主要因素,晶化温度和焙烧温度的提升不利于碱性位的充分暴露。在150℃的水热晶化温度下,葡萄糖与Al3+的摩尔比为3时的杂化复合前体经500℃焙烧得到的LiAl-MMO-150-3-500固体催化剂比表面积高达229 m2·g-1,苯酚吸附测得催化剂的总碱量为855 μmol·g-1,对苯甲醛的转化率高达88.21%。

关键词: 层状双金属氢氧化物, 杂化前体, 高比表面积, 固体碱催化剂, Knoevenagel缩合反应

CLC Number: