不同方法制得的ZnCr 2 O 4尖晶石纳米氧化物的理化性质和催化活性的研究

通过XRD，FTIR，SEM和TPR对通过溶胶-凝胶燃烧，共沉淀和pechini方法获得的亚铬酸锌尖晶石的理化性质进行了研究，并研究了其作为甲苯催化燃烧的催化剂。通过pechini方法获得的样品在甲苯的催化燃烧中表现出最高的活性。基于ZSM-5和γ-Al系支持亚铬酸锌样品2 ö 3通过用尖晶石的比例的Pechini方法制备支持2:1。负载型催化剂提高了甲苯转化率，这归因于负载型催化剂中较高的表面积和亚铬酸锌的更大还原性。这些因素也说明了ZnCr 2 O 4 / ZSM-5比ZnCr更好的催化性能。2 O 4 -Al 2 O 3。用响应面法研究了合成因子对催化剂活性的影响。该模型预测因素的相对重要性如下：煅烧温度> [柠檬酸根/硝酸根比]> [柠檬酸根/ EG比]。通过遗传算法预测了最佳条件，其中最佳条件分别在煅烧温度分别为[柠檬酸盐/硝酸盐]，[柠檬酸盐/硝酸盐]和[柠檬酸盐/ EG]的水平上达到–1 、、 – 1和0。

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Physicochemical properties of zinc chromite spinel obtained by sol–gel combustion, co-precipitation, and pechini methods were characterized by XRD, FTIR, SEM and TPR and studied as catalysts for the catalytic combustion of toluene. The sample obtained by pechini method showed the highest activity in the catalytic combustion of toluene. Supported zinc chromite samples based on ZSM-5 and γ-Al2O3 were prepared by the pechini method with the ratio of spinel to support 2:1. Supported catalysts increased the rate of toluene conversion which is ascribed to a higher surface area and greater reducibility of zinc chromite in the supported catalysts. These factors also explain the better catalytic performance of ZnCr2O4/ZSM-5 compared than ZnCr2O4–Al2O3. The effects of synthesis factors on activity of catalysts were studied by response surface methodology. The model predicted that the relative importance of factors is as follows: calcination temperature > [citrate/nitrate ratio] > [citrate/EG ratio]. The optimization condition was predicted by genetic algorithm where the optimum conditions were resulted at levels –1, –1, and 0 of calcination temperature, [citrate/nitrate], and [citrate/EG], respectively.