Reaction and Raman spectroscopic studies of alcohol oxidation on gold-palladium catalysts in microstructured reactors
Reaction and Raman spectroscopic studies of alcohol oxidation on gold-palladium catalysts in microstructured reactors
复制标题
DOI：
10.1016/j.cej.2010.08.082
复制
发表时间：
2011-03-01
影响因子：
15.1
通讯作者：
Gavriilidis, Asterios
中科院分区：
文献类型：
--
作者：
Cao, Enhong;Sankar, Meenakshisundaram;Gavriilidis, Asterios
在硅玻璃微填充床反应器（MPBRs）中，以1%（Au-Pd）/TiO 2为催化剂，无溶剂、纯氧为氧化剂，研究了苯甲醇的氧化反应。微反应器芯片的总体尺寸为23 mm x 23 mm，反应通道尺寸为0.6 mm（W）x 0.3 mm（H）x 190 mm（L）。在反应通道的出口附近引入柱结构（60 μ m（W）× 1 mm（L）40 μ m间隔的小矩形柱）以保留催化剂。在80-120 ℃的温度范围和高达5巴（a）的入口压力下研究反应。在MPBR中获得的在80和120 ℃下的苯甲醇转化率和苯甲醛选择性除了在120 ℃下的选择性之外，与来自常规玻璃搅拌反应器（GSR）的那些非常接近。甲苯在无氧条件下生成，在有氧条件下生成量增加。增加压力提高了转化率和苯甲醛选择性。对MPBR的传质阻力进行了实验研究。当气液体积流量比大于100时，在给定的液体流速（0.003mL/min）下，外部传质阻力可以忽略不计。用两种粒度范围：53-63 μ m和90-125 μ m考察催化剂粒度对反应的影响。在粒径为90-125 μ m时转化率较低，表明存在内部传质阻力。在MPBR中的原位拉曼测量使用具有不同微反应器配置的特别设计的微反应器阶段进行。从沿着反应通道的不同点处的液体袋获得的拉曼光谱可以用于获得沿着催化剂床的苯甲醛浓度分布。在催化剂表面上观察到由于形成高度无序的石墨碳而产生的谱带。(C)2010 Elsevier B. V.保留所有权利。
Oxidation of benzyl alcohol in the absence of solvent on 1% (Au-Pd)/TiO2 catalyst with pure oxygen was performed in silicon-glass micropacked-bed reactors (MPBRs). The overall size of the microreactor chip was 23 mm x 23 mm with a reaction channel dimension of 0.6 mm (W) x 0.3 mm (H) x 190 mm (L). A pillar structure (small rectangular posts of 60 mu m (W) x 1 mm (L) 40 mu m apart) was incorporated near the outlet of the reaction channel to retain the catalyst. The reaction was studied in the temperature range of 80-120 degrees C and at inlet pressures up to 5 bar(a). Benzyl alcohol conversion and benzaldehyde selectivity at 80 and 120 degrees C obtained in MPBRs were very close to those from conventional glass stirred reactors (GSRs) apart from the selectivity at 120 degrees C. Toluene was formed in the absence of oxygen, and its production was enhanced in the presence of oxygen. Increasing pressure improved both conversion and benzaldehyde selectivity. Mass transfer resistance in MPBRs was evaluated experimentally. The external mass transfer resistance could be ignored at a volumetric flow ratio of gas (STP) to liquid above 100, at a given liquid flow rate (0.003 mL/min). The effect of catalyst particle size on the reaction was examined with two ranges of particle size: 53-63 mu m and 90-125 mu m. Lower conversion was obtained with particle sizes of 90-125 mu m, indicating the presence of internal mass transfer resistances. In situ Raman measurements in MPBRs were performed using a specially designed microreactor stage with a different microreactor configuration. Raman spectra obtained from liquid pockets at different points along the reaction channel could be used to obtain the benzaldehyde concentration profile along the catalyst bed. Bands due to formation of highly disordered graphitic carbon were observed on the catalyst surface. (C) 2010 Elsevier B.V. All rights reserved.