钴基复合氧化物氧化降解甲苯的结构与催化性能

采用溶胶-凝胶法制备了钴基复合氧化物A-Co（A=Cu,Mn,Ce）,测定和评价了A-Co复合催化剂氧化降解甲苯的催化性能.结果表明,二元钴基复合氧化物氧化降解甲苯的催化活性均优于纯钴氧化物催化剂,其中,Ce-Co氧化物的t10和t90(分别为达到10%和90%的甲苯转化的温度)分别为221,238 ℃,催化活性最高.在240 ℃连续使用50 h,Ce-Co氧化降解甲苯降解转化率仍为99%以上,具有较好的催化稳定性.应用X射线衍射、氮气吸脱附、扫描电子显微镜、氢气程序升温还原和X射线光电子能谱等表征技术，研究了钴基催化剂的结构与催化性能的关系,在Ce-Co催化剂上形成的Ce⁴⁺/Ce³⁺和Co³⁺/Co²⁺氧化还原对促进了催化剂上氧的迁移,提高了表面氧的可还原性,在甲苯氧化降解过程中产生协同作用.

Structure of the Cobalt-Based Oxide and Its Catalytic Performance in Oxidation of Toluene

Cobalt-based oxides A-Co (A=Cu,Mn,Ce) and pure cobalt oxide prepared by using sol-gel method have been tested for toluene oxidation.It is found that all binary cobalt-based oxides showed higher catalytic performance in the oxidation of toluene than pure cobalt oxide.The most efficient catalyst was Ce-Co with t10 and t90 (the temperature required for achieving 10% and 90% conversion of toluene,respectively) values of 221 and 238 ℃,respectively.In addition,the stability of the Ce-Co oxide was evaluated at 99% of toluene conversion at 240 ℃ for 50 hours.The characterization techniques of X-ray diffractometry,nitrogen adsorption-desorption,scanning electron microscope,H2 temperature programmed reduction and X-ray photoelectron spectroscopy were used to explain the improved catalytic performance.The results indicated that Ce⁴⁺/Ce³⁺ and Co³⁺/Co²⁺ redox couples in the Ce-Co catalyst facilitated the mobility of oxygen and improved the reducibility of surface oxygen accounting for the synergetic effect in the oxidation of toluene.