合成体系中NO- 3与HMT的物质的量比对AlOOH结构及催化性能的影响

来源期刊:中南大学学报(自然科学版)2017年第1期

论文作者:吴旭 阴青青 黄艳丽 杜亚丽 谢鲜梅

文章页码:39 - 47

关键词:HMT水热分解;AlOOH;催化性能;苯甲醛;安息香乙醚

Key words:HMT hydrolysis; AlOOH; catalytic performances; benzaldehyde; benzoin ethyl ether

摘    要:采用HMT水热分解法,通过调控 与HMT的物质的量比(n( )/n(HMT))在不同合成体系下制备AlOOH催化剂,并就其在苯甲醛和乙醇一步合成安息香乙醚中的催化性能进行评价。通过XRD,FT-IR,TG-DTG,BET,TEM及NH3-TPD-MS对催化剂进行表征。研究结果表明:调控合成体系中n( )/n(HMT)可以制备出结构和形貌不同的勃姆石。合成环境在构建AlOOH组成结构的基础上进而影响着其催化性能。取苯甲醛3 mL、乙醇40 mL、不同n( )/n(HMT)制备的AlOOH催化剂0.2 g,当反应温度为70 ℃,时间为40 min时,安息香乙醚的选择性均可达100%。高n( )/n(HMT)下制备的AlOOH能使苯甲醛的转化率达68.9%,低n( )/n(HMT)下制备的AlOOH仅使苯甲醛的转化率为32.3%,而调控n( )/n(HMT)使最终合成体系为中性条件下制备的AlOOH几乎没有催化活性(苯甲醛的转化率仅为3.08%)。不同的催化性能与制备所得AlOOH结构和形貌密切相关,而AlOOH催化剂酸量的不同构建是催化差异的本质原因。

Abstract: AlOOH were fabricated by hexamine (HMT) hydrolysis method through modulating the molar ratio of NO3- to HMT (n(NO3-)/n(HMT) and their catalytic performances toward synthesis of benzoin ethyl ether from benzaldehyde and ethanol were evaluated. Samples obtained at various molar ratio of to HMT were characterized by XRD, FT-IR, TG-DTG, BET, TEM and NH3-TPD-MS. The results show that AlOOH obtained at different molar ratios of NO3- to HMT has different structures and morphologies. The further evaluation of catalytic activity demonstrates that ambient atmosphere can alter the structure of AlOOH, which has a significant effect on the catalytic behavior. All synthesized catalysts present 100% selectivity of benzoin ethyl ether under following reaction condition: temperature 70 ℃, benzaldehyde 3 mL, ethanol 40 mL, catalyst 0.2 g, reaction time 40 min, at higher molar ratio of to HMT, AlOOH displays fine catalytic activity (68.9% conversion of benzaldehyde), while at lower molar ratio of NO3- to HMT a poor activity (32.3% conversion of benzaldehyde) is obtained and at neutral ambient atmosphere there is almost no catalytic activity (3.08% conversion of benzaldehyde). The totally different catalytic activity has close relation to the structures and morphologies of AlOOH synthesized under different pH values, and the amount of acid is responsible for the different catalytic performances.

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