细长柱形Cu-Mn/Al_(2)O_(3)催化剂的控制合成及其对甲烷催化燃烧的影响

Controllable synthesis and catalytic performance of the slender Cu-Mn/Al_(2)O_(3) monolithic catalyst on the methane combustion

为提高煤矿风排瓦斯的处理和利用效率,采用溶胶凝胶法控制合成条件以制备三维交联通透型的多级孔道细长柱形Al_(2)O_(3),并以其为载体用水热合成法制备负载量极低的非贵金属Cu-Mn/Al_(2)O_(3)整体柱催化剂。对催化剂的结构和物理化学性质进行BET、SEM、XRD和XPS表征,并采用微型固定床反应器测试催化剂对低浓度甲烷燃烧的转化效率。结果表明,通过控制模具形状、尺寸以及干燥温度等条件可实现对催化剂形状的控制合成。减小陈化过程的凝胶尺寸和降低干燥过程中的水分和溶剂脱除速率等均可得到细长柱形Cu-Mn/Al_(2)O_(3)催化剂。催化剂负载活性组分Cu、Mn的摩尔比为1:2时,柱形催化剂的比表面积更高,可达174.5m^(2)/g,比块状催化剂比表面积高54.8m^(2)/g;催化剂活性组分负载量极低的情况下,柱形催化剂活性较高,T_(90)为560℃,比块状催化剂低50℃。细长柱形的催化剂内部具有独特的微观孔结构即传质通道,该传质通道有利于催化剂与物料的充分接触以增加反应效率,此外柱形催化剂整体成型具备较高机械强度,因此为实际矿井中用于加快风排瓦斯的燃烧效率的催化剂应用奠定了基础。

The paper is inclined to synthesize the slender column of the Cu-Mn/Al_(2)O_(3) monolithic catalyst by using the slender Al_(2)O_(3) with the 3D cross-linked multi-stage channel by the sol-gel method as the carriers and the Cu-Mncomposite as active components so as to reduce the non-CO2 greenhouse gas emission and improve the efficiency of the gas treatment and utilization. For the said synthesis of the slender column Al_(2)O_(3) in the sol-gel process,we have prepared to adopt the hydrothermal synthesis method with very low load for the Cu-Mn/Al_(2)O_(3) monolithic catalyst. At the same time,we have also managed to characterize the structure and the physicochemical properties of the carrier and the catalyst via the BET,SEM,XRD and XPS. Moreover,the conversion efficiency of the low concentrated methane component has also been tested in the micro-fixed bed reactor. Thus,the results of our synthesis show that the shape and the size of the Al_(2)O_(3) carriers can be controlled by choosing the suitable model shape and its size by managing to change the drying temperature and the other factors concerned. And,since the slender column of Al_(2)O_(3) carrier can be prepared successfully both by decreasing the sol size of the aging process and the abatement of the removal rate of the water and solvent content in the drying process,the hydrothermal synthesis of Cu-Mn/Al_(2)O_(3) should be taken prior to the impregnation method in reference to the crystallizing temperature and pressure when Cu-Mnactive components are loaded. The results of our above synthesis show that the specific surface area of the slender column Cu-Mn/Al_(2)O_(3) catalyst can be made much higher,to be exact,as high as 174. 5 m^(2)/g when the mole ratio of Cu: Mn = 1: 2,which is equal to 54. 8 m^(2)/g,that is,much higher than the bulk catalyst,whose catalytic performance of the Cu-Mn/Al_(2)O_(3) can be taken to be related to the shape of the catalyst with its slender column to get much higher.And,when,T_(90) is 560 ℃,or,even if the loading amount of the active component tends to be rather low,say,50 ℃ lower than that of the bulk catalyst. This kind of slender column catalyst can be regarded as the uniquely microscopic structure and able to provide for a fast massive transfer channel and highly conducive to the uniform and full contact with the feed. Moreover,the high mechanical strength of the slender Cu-Mn/Al_(2)O_(3) catalyst can also help to enhance the application prospect in the field of VAM catalytic combustion with the vast ventilation air quantity.