The morphologies of CuO/CeO2-ZrO2 catalysts were successfully controlled by simply changing the synthesis temperature using hydrothermal method. The catalytic performance for toluene oxidation was correlated with the characterization results of HRTEM, BET, XRD, H2-TPR, Raman, and O2-TPD. It was found that toluene can be oxidized into CO2 and H2O completely over the obtained catalysts, and the rod-like Cu/Ce-Zr-100 exhibits the best activity and CO2 selectivity. The rod-like CeO2-ZrO2 supports preferentially exposes (110) and (100) crystal planes of CeO2, which provides more oxygen vacancies and stronger interaction between CuO and the support in Cu/Ce-Zr-100. And the strong synergetic effect in Cu/Ce-Zr-100 promotes the dispersion of CuO on the support surface, leading to the enhancement of reducibility, oxygen vacancy concentration, adsorption and activation of gaseous oxygen, which are responsible for the good catalytic performance of toluene oxidation.

采用溶胶凝胶法制备了双主金属、双助剂的CuxMn1-xCe0.75Zr0.25Oy催化剂,在固定床反应器中评价了催化剂降解甲苯的性能,并采用XRD、H2-TPR、O2-TPD和Raman对催化剂进行表征.试验结果表明:催化剂中Cu含量的增加有助于增强Cu-Ce金属之间的相互作用,增加催化剂中的氧空位浓度和晶格氧含量,提高催化剂低温还原性,从而促进催化活性的提高.Cu1CeZr催化剂降解甲苯活性最好,其完全降解甲苯的温度(T100)为220℃,比Mn1CeZr催化剂低60℃.

以TiO2为载体,采用等体积浸渍法制备了负载型CuxMn1-xCe0.75Zr0.25/TiO2(x=1.0、0.75、0.5、0.25、0)负载型催化剂,采用XRD、H2-TPR、O2-TPD和XPS等方法对催化剂进行了表征,并通过低温等离子体协同催化剂对大流量的甲苯模拟废气进行了催化降解反应研究.结果表明,Cu和Mn单主金属催化剂的活性优于Cu-Mn双主金属催化剂,其原因是双金属催化剂中Mn的添加减弱了Cu与助剂Ce之间的相互作用,使得催化剂的晶格氧减少,低温还原性能降低.在反应初期,甲苯降解主要依赖于催化剂的活性,具有较好的低温还原性以及丰富的氧空穴和晶格氧含量的CuCe0.75 Zr0.25/TiO2的活性最好;Mn具有较强的O3分解能力,当等离子体比能密度(SED)增加到一定值后,等离子体与催化剂的协同作用增强,从而使得MnCe0.75 Zr0.25/TiO2催化剂活性高于CuCe0.75 Zr0.25/TiO2,强化了甲苯的脱除.

The self-sustained combustion of toluene on the Cu-Ce-Zr based catalysts with different activity has been carried out in a micro-tube with inner diameter of 4 mm. It was shown that the lean-combustion limits over CuCe0.75Zr0.25Ox-BC catalyst with the higher activity were less than that on CuCe0.75Zr0.25/TiO2 catalyst at the same flow rate, and the minimum of equivalence ratio (?) was 0.024 under the flow rate of 200 ml/min. The residence time of the mixed gas on the catalyst surface declined with the increasing of flow rate, making the highest surface wall-temperature range shift to the back of catalyst bed. Toluene could maintain self-sustained combustion even when the heat loss was as high as 91.9%. Combined with the theoretical model, the heat transport of toluene self-sustained combustion in micro-tube was calculated. The self-sustained combustion in a fixed-bed reactor was realized with reducing the upper limit of temperature runaway??s impacts for the reactor and catalysts.

A series of CuCe0.75Zr0.25Ox catalysts (CCZ) were synthesized based on the environmental-friendly bacterial cellulose (BC) by using the sol-gel method. The corresponding synthesis mechanism, physicochemical properties of the catalysts and catalytic performances for toluene oxidation were comprehensively studied. In the presence of BC without sugar, the CCZ-A synthesized by ethanol-gel exhibits better catalytic activity than the CCZ-W synthesized by water-gel, which may be due to the different roles of BC in different solvents. However, it is worth noting that the graft copolymerization between BC and active metal (Ce4+, Cu2+) is the same process in both water-gel and ethanol-gel. The activity of CCZ-SW synthesized by water-gel using BC with sugar is obviously higher than that of CCZ-W and CCZ-A. The temperature of complete degradation of toluene over CCZ-SW is 205 degrees C, which is 35 degrees C lower than that of CCZ-W. The results from BET, Raman and H-2-TPR indicate that the larger the specific surface area, the more oxygen vacancies and better low-temperature reducibility, that are mainly responsible for the excellent activity of CCZ-SW. The existence of sugar in BC could hinder the agglomeration of active metal particles during the calcination process. Combined with the results of insitu DRIFT, the adsorbed toluene on the catalyst surface is oxidized into alkoxide, aldehydic and carboxylic acid species as intermediates before the complete oxidation into CO2 and H2O.((1))