La_(1-x)Ce_xFe_(0.7)Co_(0.3)O_(3-δ)网状多层纳米纤维对碳烟催化燃烧性能研究

Multilayer arrangements of La_(1-x)Ce_xFe_(0.7)Co_(0.3)O_(3-δ) nanofiber webs for effective soot catalytic combustion

采用静电纺丝法制备了一系列钙钛矿催化剂La_(1-x)Ce_xFe_(0.7)Co_(0.3)O_(3-δ)(x=0、0.1、0.2、0.3和0.4),并采用XRD、SEM、FT-IR、H2-TPR和O_2-TPD等技术分析了Ce掺杂量对催化剂结构、微观形貌及理化特性的影响.同时,采用程序升温氧化(TPO)技术评价了催化剂对碳烟的催化燃烧活性,探讨了催化剂对碳烟的催化燃烧机理.结果表明:在La_(1-x)Ce_xFe_(0.7)Co_(0.3)O_(3-δ)中掺杂适宜的Ce有助于提高催化剂活性,改善催化剂比表面积和孔容积.在催化剂与碳烟松散接触条件下,当Ce掺杂量(质量百分比)为0.3时,所制备的La_(0.7)Ce_(0.3)Fe_(0.7)Co_(0.3)O_(3-δ)对碳烟的起燃温度(T_(ig))、最大燃烧温度(T_m)和燃尽温度(T_f)分别为329.5、409.8和421.1℃,呈现良好的催化氧化活性.碳烟最大转化效率为98.7%,平均活化能为123 kJ·mol^(-1),CO_2选择率为98.2%,实现了对柴油机碳烟排放污染物有效"过滤+催化燃烧"的双重目标.

Perovskite-type La（1-x）CexFe0.7Co0.3O3-δx = 0,0.1,0.2,0.3,0.4） catalysts were prepared by electrospinning method,and the catalysts were characterized by x-ray diffraction（ XRD）,scanning electron microscope（ SEM）,Fourier transform infrared spectroscopy（ FTIR）,X-ray photoelectron spectroscopy（ XPS）, H2-temperature-programmed reduction（ H2-TPR） and O2-temperature-programmed desorption（ O2-TPD）. The catalysts performances were optimized in a micro fixed-bed reactor through doping appropriate amount of Ce into A sites of La（1-x）CexFe0.7Co0.3O3-δ Soot catalytic combustion activities of catalysts were evaluated by temperature programmed oxidation（ TPO）. The test results showed that catalytic activity of La（1-x）CexFe0.7Co0.3O3-δas improved through doping appropriate amount of Ce,and the specific surface area and pore volume of catalysts increased accordingly. When doping amount of Ce was 0.3,the resultant La0.7Ce0.3Fe0.7Co0.3O3-δresented good catalytic combustion activity for soot. Under the loose contact condition of catalyst and soot,light-off temperature（ Tig）,maximum combustion temperature（Tm） and total conversion temperature（Tf） of La0.7Ce0.3Fe0.7Co0.3O3-δwere 329.5,409.8 and 421.1 ℃,respectively. Maximum soot conversion efficiency was 98.7%,average activation energy was 123 kJ·mol-1,and CO2 selectivity rate reached 98. 2%. Therefore,it is verified that La0.7Ce0.3Fe0.7Co0.3O3-δatalyst had better catalytic combustion activity in reducing soot emissions from diesel engine exhaust.