MnCr_(2)O_(4)催化剂的制备方法及其SCR脱硝性能研究

Preparation of MnCr_(2)O_(4) catalysts and their NH3-SCR performance

为了探明不同方法制备Mn-Cr尖晶石型催化剂的可行性,通过水热法、沉淀法和溶胶凝胶法分别制备了MnCr_(2)O_(4),确定了该催化剂的较佳制备条件,并对所制得的催化剂的脱硝效率和N2选择性进行了测试对比。此外,比较了不同制备方法所得催化剂的物相组成,同时对催化剂的构效关系进行了探究与分析。结果表明,溶胶凝胶法制备的MnCr_(2)O_(4)催化剂不仅具有纯尖晶石相,且展现出最佳的脱硝性能。在反应空速为60000 h^(-1)时,溶胶凝胶法制备的催化剂样品在169~341℃下脱硝效率高于90%。与水热法、沉淀法相比,溶胶凝胶法制备的MnCr2O4催化剂选择性催化还原(SCR)活性最佳的原因在于其具有高摩尔分数的Mn^(4+)、Cr^(5+)及Oα,数量较多且酸性较强的酸位点,以及较强的可还原性。

In order to investigate the feasibility of preparing Mn-Cr spinel-type catalysts by different methods,MnCr_(2)O_(4) was prepared by hydrothermal,precipitation and sol-gel methods,respectively.The optimal preparation conditions were determined,and the de-NOx efficiency and N2 selectivity were studied.In addition,the phase compositions of the catalysts obtained were compared,and the structure-activity relationship of the catalysts was explored and analyzed.The results show that the MnCr_(2)O_(4) catalyst prepared by the sol-gel method demonstrates pure spinel phase and exhibits the best de-NOx performance.De-NOx efficiency of the catalyst prepared by the sol-gel method was over 90%within 169-341℃under gas hourly space velocity of 60000 h^(-1).Compared with hydrothermal and precipitation methods,the best SCR performance of the MnCr_(2)O_(4) catalyst from the sol-gel method can be attributed to its high abundant of Mn^(4+),Cr^(5+),and Oα,the largest acid sites,and the strongest reducibility.