Continuous Heterogeneously Catalyzed Oxidation of Benzyl Alcohol in a Ceramic Membrane Packed-Bed Reactor
Continuous Heterogeneously Catalyzed Oxidation of Benzyl Alcohol in a Ceramic Membrane Packed-Bed Reactor
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DOI：
10.1021/acs.oprd.5b00220
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发表时间：
2015-12-01
影响因子：
3.4
通讯作者：
Gavriilidis, Asterios
中科院分区：
文献类型：
--
作者：
Constantinou, Achilleas;Wu, Gaowei;Gavriilidis, Asterios
采用陶瓷膜反应器对苯甲醇连续催化氧化反应进行了研究。反应器具有同心构造。内管形成用于催化剂填充床（0. 9 wt % Au-Pd/TiO 2，粒度90-125 μ m）的环形空间，液相（纯苯甲醇或溶于邻二甲苯的苯甲醇）流过该环形空间。随后是管状陶瓷膜，其由氧化铝层和氧化锆顶层组成，标称平均孔径为50 nm。膜的作用是为气体和液体接触提供界面。将纯氧进料到反应器外壳中的膜的相对侧。温度影响转化率，但不影响选择性，这可能是因为氧气供应不足。然而，增加催化剂接触时间或降低苯甲醇浓度可以提高选择性和转化率，这表明关键参数是膜的氧气供应与反应的氧气需求之间的平衡。通过调整操作参数，反应性能得到改善。在3.2bara的气体压力、24444 g（催化剂）·s/g（醇）催化剂接触时间、0.5M苯甲醇浓度和120 ℃的温度下获得苯甲醛的选择性88%和苯甲醇的转化率75%。该性能与模拟滴流床操作相当，其中氧气和底物在进入催化剂填充床之前预混合。膜反应器提供了更安全的操作，因为避免了在滴流床中形成的易燃氧气/有机混合物。
A ceramic membrane reactor was investigated for the continuous catalytic oxidation of benzyl alcohol with oxygen. The reactor had a concentric configuration. An inner tube created an annulus for the catalyst packed-bed (0.9 wt % Au-Pd/TiO2, particle size 90-125 mu m) through which the liquid phase (benzyl alcohol, neat or dissolved in o-xylene) flowed. This was followed by the tubular ceramic membrane, which consisted of layers of alumina and a zirconia top layer with a nominal average pore size of 50 nm. The role of the membrane was to provide an interface for gas and liquid to come in contact. Pure oxygen was fed to the opposite side of the membrane in the outer shell of the reactor. Temperature affected conversion but not selectivity, possibly because of insufficient supply of oxygen. However, increasing catalyst contact time or decreasing benzyl alcohol concentration improved selectivity and conversion, indicating that a key parameter was the balance between oxygen supply by the membrane vs oxygen demand by the reaction. By adjusting the operating parameters, reaction performance improved. Selectivity to benzaldehyde 88% and conversion of benzyl alcohol 75% were obtained at 3.2 bara of gas pressure, 24444 g(cat).s/g(alcohol) catalyst contact time, 0.5 M benzyl alcohol concentration, and temperature of 120 degrees C. This performance was comparable to simulated trickle bed operation, where oxygen and substrate were premixed before entering the catalyst packed bed. The membrane reactor offers safer operation, since flammable oxygen/organic mixtures formed in the trickle bed are avoided.