Cu-Co催化剂中Ce、La的添加对催化燃烧降解正庚烷性能的影响

Effects of Ce and La in Cu-Co Catalysts on Catalytic Combustion of n-Heptane

采用共沉淀法制备了系列MxCu1.5-xCo6-O复合氧化物催化剂(M=Ce,La;x=0.3～0.7)。借助N2吸脱附实验、X射线衍射(XRD)、扫描电子显微镜(SEM)、H2程序升温还原(H2-TPR)、O2程序升温脱附(O2-TPD)和X射线光电子能谱(XPS)对催化剂进行表征,并在反应体积空速15000 h-1,氧气体积分数10%,150～275℃温度范围内,以体积分数0.18%正庚烷为降解底物,于固定床连续反应器-气相色谱在线检测装置上考察了催化剂对正庚烷的催化燃烧降解活性。结果显示,适量Ce、La的添加能提高催化剂比表面积、氧化还原性能及吸附氧能力,进而提高催化剂的活性。其中Ce0.5Cu1Co6-O与La0.7Cu0.8Co6-O相对催化活性最优,正庚烷转化率达90%时的最低转化温度分别为180.80和184.73℃,相比于未改性Cu-Co催化剂分别降低15和10℃。稳定性考察结果表明,Ce0.5Cu1Co6-O与La0.7Cu0.8Co6-O具有一定的稳定性。

MxCu1.5-xCo6-O（M=Ce, La; x=0.3-0.7） catalysts were prepared via co-precipitation, which were characterized by N2 adsorption-desorption, X-ray diffraction（XRD）, scanning electron microscopy（SEM）, H2 temperature programmed reduction（H2-TPR）, O2 temperature programmed desorption（O2-TPD） and X-ray photoelectron spectroscopy（XPS）. The catalytic activity of the catalysts for oxidative degradation of 0.18% n-heptane was investigated in a continuous fixed bed reactor with GHSV of 15000 h-1 and oxygen concentration of 10%. The results show that certain amount of cerium and lanthanum doping can enhance surface area, reducibility and oxygen-adsorptive capacity of the catalysts,which improves the performance of the mixed oxides. Ce0.5 Cu1 Co6-O and La0.7 Cu0.8 Co6-O are the most active catalysts with activity of 90% n-heptane conversion at 180.80℃ and 184.73℃, respectively, which are 15℃ and 10℃ lower than those of undoped Cu-Co catalysts. Ce0.5 Cu1 Co6-O and La0.7 Cu0.8 Co6-O also show good stability in this study.