制备条件对LaMnO3催化氧化碳黑活性的影响

通过改变煅烧温度、煅烧时间和前驱体溶液pH值,在不同条件下用溶胶凝胶法制备了LaMnO3钙钛矿型催化剂。使用BET、XRD等实验手段对催化剂进行了表征测试,利用热重分析仪对催化剂催化氧化碳黑的活性开展了程序升温氧化实验研究,并用Coats-Redfern方法进行了反应动力学分析。实验结果表明,煅烧温度对LaMnO3钙钛矿催化剂的形成起到关键作用,973K煅烧的催化剂可以获得最大的反应活性;煅烧时间对钙钛矿的形成也有一定影响,煅烧超过6h的催化剂活性较高;前驱体溶液pH值呈碱性时,可以获得最大的催化剂表面积以及表面活性位密度,从而提高催化剂的整体活性。

Effect of preparation conditions on catalytic activity of LaMnO3 on oxidation of carbon black

Various LaMnO_3 perovskite-type catalysts were prepared using the Sol-Gel method with various sintering temperatures, sintering times, and pH of the precursor solutions. The catalysts were characterized by BET and XRD. The catalytic activities of LaMnO_3 on carbon black oxidation were measured using Temperature Programming Oxidation (TPO) on TGA, with the Coats-Redfern method used for the dynamic analysis. Experimental results show that the sintering temperature is a key parameter affecting the formation of LaMnO_3 perovskite-type catalysts, with the catalyst sintered at 973 K more active than those sintered at 773 K or 1173 K. The sintering time also affects the LaMnO_3 formation, with better and more stable catalytic activity for sintering time longer than 6 hours. Increasing pH values of the precursor solution increased the specific surface area of the catalyst, the active site concentration on the catalyst surface and the catalytic activity.