氧化钴纳米球与低载银的相互作用及其对炭烟氧化的影响

The interaction between cobalt oxide nanospheres and low-loaded silver and its effects on soot oxidation

通过水热法合成纳米球状的钴氧化物和锰氧化物载体,并利用浸渍法制备出低载银量(质量分数0.9%~1.5%)的Ag/Co_(3)O_(4)和Ag/Mn_(2)O_(3)催化剂。在紧密接触条件下,Ag/Co_(3)O_(4)的T_(10)值、T_(50)值和T_(90)值分别为250℃、284℃和311℃,表现出优异的炭烟催化氧化活性。采用XRD、H_(2)-TPR、TG、EPR、XPS等技术对制备的催化剂进行表征,结果表明:当钴氧化物和锰氧化物中分别引入Ag后,Ag/Co_(3)O_(4)表现出更好的炭烟燃烧性能,这是由于Ag与Co_(3)O_(4)之间具有更强的金属-载体相互作用,使Ag/Co_(3)O_(4)呈现出更多Co^(3+)物种及适量氧空位,增加了其表面活性氧数量,提高了氧的迁移率,进而有效提升了Ag/Co_(3)O_(4)氧化炭烟的能力。此外,Ag的金属性质和催化剂的纳米球状形貌都有利于炭烟催化氧化反应的进行。

In this paper,nano-spherical cobalt oxide and manganese oxide supports were synthesized by hydrothermal method,and the Ag/Co_(3)O_(4)and Ag/Mn_(2)O_(3)catalysts with low silver loading(0.9%~1.5%,mass fraction)were prepared by impregnation method.Under tight contact conditions,the T_(10),T_(50)and T_(90)values of Ag/Co_(3)O_(4)were 250℃,284℃and 311℃,showing excellent catalytic activity for soot oxidation.The prepared catalysts were characterized by XRD,H_(2)-TPR,TG,EPR,XPS and other techniques.The results showed that when Ag was introduced into cobalt oxide and manganese oxide,respectively,Ag/Co_(3)O_(4)exhibited better soot combustion performance.This is due to the stronger metal-support interaction between Ag and Co_(3)O_(4),which creates more Co^(3+)species and appropriate oxygen vacancies on Ag/Co_(3)O_(4),increases the surface active oxygen numbers and the oxygen mobility,and effectively improves the ability of Ag/Co_(3)O_(4)to oxidize soot.In addition,the metallic properties of Ag and the nano-spherical morphology of the catalysts are also conducive to the catalytic oxidation of soot.