CuMnCeO_(x)/Al_(2)O_(3)/CH催化剂的制备及微波催化燃烧VOCs性能

Preparation and performance of CuMnCeO_(x)/Al_(2)O_(3)/CH catalyst in microwave catalytic combustion of VOCs

针对整体式催化剂载体比表面积小和涂层脱落等问题,采用聚乙二醇200 (PEG200)为粘结剂在蜂窝堇青石(CH)载体表面涂覆氧化铝(Al_(2)O_(3))涂层,等体积浸渍法制备CuMnCeO_(x)/Al_(2)O_(3)/CH催化剂,微波催化燃烧VOCs以考察其催化性能。结果显示,当酸铝比(nH+/n(Al^(3+)))为0.262 5、mPEG200/mAlOOH为1.5时,PEG200与AlOOH以氢键连接得到分散度高的铝溶胶,涂覆煅烧后PEG的造孔效应改善了载体形貌,为活性组分的负载提供了更多附着位点。在甲苯初始质量浓度1 000 mg·m^(-3)和处理气量0.12 m^(3)·h^(-1)的实验条件下,CuMnCeO_(x)/Al_(2)O_(3)/PEG(1.5)/CH催化剂降解甲苯的T90为200℃,比CuMnCeO_(x)/CH和CuMnCeO_(x)/Al_(2)O_(3)/PEG(0.0)/CH催化剂分别降低了62℃和53℃。SEM、BET和XRD等表征发现,片状γ-Al_(2)O_(3)涂层增大了载体比表面积和孔容,活性粒子更均匀地分布于催化剂表面,为VOCs氧化提供更多的有效活性位点;过渡金属氧化物表面丰富的活性位点和Cu^(+)/Cu^(2+)与Mn^(3+)/Mn^(4+)间价态转化产生的氧空穴提高了催化剂的催化活性和VOCs的矿化效果。该研究结果可为高活性催化剂的制备及其微波催化燃烧VOCs技术应用提供参考。

To solve the problems of small specific surface area and coating detachment for the carrier of monolithic catalyst,polyethylene glycol 200(PEG200)was selected as a binder to prepare alumina(Al_(2)O_(3))coating onto the surface of cordierite honeycomb(CH)carrier.Subsequently,CuMnCeO_(x)/Al_(2)O_(3)/CH catalyst was prepared by an equivalent–volume impregnation method,and its activity was checked by microwave catalytic combustion of VOCs.Results showed that PEG200 and AlOOH were connected by hydrogen bond to form aluminum sol with high dispersion under conditions of 0.2625 of acid aluminum ratio()and 1.5 of mPEG200/mAlOOH,and the carrier morphology was improved by the pore-forming effect of PEG after coating and calcinations,which provided more attachment sites for the load of active components.Under experimental conditions of gas flow rate at 0.12m^(3)·h^(-1) and initial concentration of toluene at 1000 mg·m^(-3),the T90 of CuMnCeO_(x)/Al_(2)O_(3)/PEG(1.5)/CH catalyst for toluene degradation was 200℃,which lessened by 62℃and 53℃while compared with CuMnCeO_(x)/CH catalyst and CuMnCeO_(x)/Al_(2)O_(3)/PEG(0.0)/CH catalyst,respectively.Based on characterization of SEM,BET and XRD,it was revealed that plate-likeγ-Al_(2)O_(3) coating increased the specific surface area and pore volume of the carrier,which promoted more uniform distribution of active particles on the catalyst surface and provided more effective active sites for VOCs oxidation.The abundant active sites on transition metal oxides’surface along with oxygen vacancies that generated by valence transformation between Cu^(+)/Cu^(2+)and Mn^(3+)/Mn^(4+),enhanced effectively catalytic activity of the catalyst and mineralization performance of VOCs.The study provides a theoretical base on the preparation of high-performance catalyst and the application of microwave catalytic combustion technology for VOCs treatment.