钙钛矿催化材料La_(1-x)Ce_xCoO_(3+δ)的制备、表征及甲烷燃烧催化性质

Preparation and physico-chemical characterisation of La_(1-x)Ce_xCoO_(3+δ) perovskite catalyst and its methane catalytic combustion

采用柠檬酸发泡法制备了钙钛矿LaCoO3催化材料;研究了Ce对La进行掺杂替代对催化材料性能的影响;通过BET、XRD、SEM等手段对催化材料进行了物性表征;以甲烷完全燃烧为目标反应,研究了钙钛矿La1-xCexCoO3+δ的催化性能。结果表明:铈掺杂对材料晶相有较大影响,当掺杂量x小于0.3时,粉体晶型基本不变,而当掺杂量达到0.5时,有明显CO3O4晶相出现,LaCoO3钙钛矿晶相完整性遭到破坏,当掺杂量大于0.7时,钙钛矿晶相大大弱化甚至消失;LaCoO3是一种性能优良的甲烷燃烧催化材料,Ce的掺杂替代对催化材料活性有明显影响,并增强了催化材料的高温稳定性能,铈最佳掺杂量为0.3;前驱体经700℃焙烧形成了较为完整的钙钛矿晶型,经800℃焙烧后,催化材料最高活性为:t10%=390℃,t90%=603℃。

Perovskite oxides LaCoO_3 methane catalytic materials were prepared with citrate complexation and bubbling method. The cerium doping effect was studied in series La_1-xCe_xCoO_3+δ materials by BET, XRD and SEM techniques. And their catalytic behaviours were also studied with methane catalytic complete combustion as probe reaction. The results show that doped cerium has great effects on the crystal phase formed. When doped cerium content x is less than 0.3, the phases of powders are little changed. When doped cerium x is up to 0.5, obvious Co_3O_4 phase is discovered, and the integrity of LaCoO_3 perovskite crystal phase is broken. When x is over 0.7, perovskite crystal phase is greatly weakened or completely disappeared. Considering the crystal phase of powders, the optimum cerium doping content is about 0.3. Perovskite oxides LaCoO_3 are good methane catalytic materials. Doping cerium has some positive activity effect and the thermal stability of the material is also enhanced. The perovskite oxide can be formed at lower calcination temperature, about 700 ℃, and when x is 0.3, the best catalytic activity is acquired as t_10%=390 ℃ and t_90%=603 ℃ in series of La_1-xCe_xCoO_3+δ materials calcinated at 800 ℃.