Ce-O和Fe-Ce-O催化剂的固相合成及其CH_4催化燃烧性能

以(NH4)2Ce(NO3)6为原料,选用葡萄糖为络合剂,采用研磨固相法制备了在不同温度下焙烧的氧化铈(Ce-O)和掺杂铁的氧化铈(Fe-Ce-O)催化剂。用X射线衍射法表征了催化剂的结构;用程序升温还原法测试了催化剂的还原性能;考察了经不同温度焙烧后,掺杂铁对Ce-O催化剂的CH4催化燃烧活性的影响。实验结果表明,掺杂铁后的Fe-Ce-O催化剂的粒径变小、还原性能增强、CH4催化燃烧活性提高。经400℃焙烧的Fe-Ce-O催化剂呈现单一的CeO2物相,属立方晶系;经800℃和 1 200℃焙烧的Fe-Ce-O催化剂以CeO2为主要物相,并有少量Fe2O3物相。与未掺杂铁的Ce-O催化剂相比,Fe-Ce-O催化剂具有较高的CH4催化燃烧活性。

Solid-Phase Synthesis of Ce-O, Fe-Ce-O Catalysts and Their Catalytic Activities in Methane Combustion

Cerium oxide ( Ce-O) and Fe doped cerium oxide ( Fe-Ce-O) catalysts were prepared separately by solid-phase milling of(NH4)2Ce(NO3 )6 with glucose as complex agent and by solid-phase milling of (NH4)2Ce(NO3)6 +Fe(NO3)3 with glucose as complex agent. The milled mixtures were calcined at 400,800, and 1 200 ℃ for 3 h respectively. The obtained catalysts were characterized by means of XRD and TPR. Activities of catalysts were evaluated by methane combustion reaction. Doping of Fe led to particle size decreasing, improving of catalyst activities, and enhancing their reductibility. XRD spectra showed that single phase cubic CeO2 existed in Fe-Ce-O catalyst calcined at 400℃. With increasing of calcination"temperature,the diffraction peaks of tetragonal Fe2O3 appeared, indicating the improvement of crystal structure of Fe-Ce-O catalyst. But CeO2 was still the main phase of Fe-Ce-O catalyst calcined at 800℃ and 1 200℃. Fe-Ce-O catalyst was higher in catalytic activity for methane combustion than Ce-O catalyst.