Gas-phase dehydration of glycerol to acrolein catalysed by caesium heteropoly salt
Gas-phase dehydration of glycerol to acrolein catalysed by caesium heteropoly salt
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DOI：
10.1016/j.apcata.2010.01.043
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发表时间：
2010-04-15
影响因子：
5.5
通讯作者：
Kozhevnikov, Ivan V.
中科院分区：
文献类型：
--
作者：
Alhanash, Abdullah;Kozhevnikova, Elena F.;Kozhevnikov, Ivan V.
12-钨磷酸铯，Cs2.5H0.5PW12O40（CsPW），具有强布朗斯台德酸中心，是在275 ℃和1巴压力下在气相法中甘油脱水成丙烯醛的活性催化剂。在98%丙烯醛选择性下，初始甘油转化率为100%，然而，由于催化剂焦化，随着运行时间显著降低（6小时后为40%），而不损害丙烯醛选择性。用铂族金属（PGM）（0.3-0.5%）掺杂CsPW与共进料氢气一起改善催化剂对失活的稳定性，同时保持对丙烯醛的高选择性。发现铂族金属的增强效应按Ru <Pt < Pd的顺序增加。催化剂0.5%Pd/CsPW在甘油转化率为79%时，丙烯醛选择性为96%，在275 ℃和5小时的反应时间下，丙烯醛的比生成速率为23 mmol h（-1）g（cat）（-1），超过了以前报道的负载型杂多酸的比生成速率（5-11 mmol h（-1）g（cat）（-1）/总催化剂质量）。证据是关于甘油脱水丙烯醛所需的酸性网站的性质，支持强布朗斯台德网站的重要性，这个反应。(C)2010爱思唯尔有限公司版权所有。
Caesium 12-tungstophosphate, Cs2.5H0.5PW12O40 (CsPW), possessing strong Bronsted acid sites is an active catalyst for the dehydration of glycerol to acrolein in the gas-phase process at 275 C and 1 bar pressure. The initial glycerol conversion amounts to 100% at 98% acrolein selectivity, however, decreases significantly with the time on stream (similar to 40% after 6 h) due to catalyst coking, without impairing acrolein selectivity. Doping CsPW with platinum group metals (PGM) (0.3-0.5%) together with co-feeding hydrogen improve catalyst stability to deactivation, while maintaining high selectivity to acrolein. The enhancing effect of PGM was found to increase in the order: Ru similar to Pt < Pd. The catalyst 0.5%Pd/CsPW gives 96% acrolein selectivity at 79% glycerol conversion, with a specific rate of acrolein production of 23 mmol h(-1) g(cat)(-1) at 275 C and 5 h time on stream, exceeding that reported previously for supported heteropoly acids (5-11 mmol h(-1) g(cat)(-1) per total catalyst mass). Evidence is presented regarding the nature of acid sites required for the dehydration of glycerol to acrolein, supporting the importance of strong Bronsted sites for this reaction. (C) 2010 Elsevier B.V. All rights reserved.