SCS法制备Co_(3)O_(4)催化氧化低浓度甲烷

Catalytic Oxidation of Low Concentration Methane by Co_(3)O_(4)Prepared via SCS Method

前驱物中氧化剂(硝酸钴)/燃料(柠檬酸)配比对溶液燃烧法制备的Co_(3)O_(4)催化氧化低浓度甲烷性能的影响极大。随着燃料占比的增多,Co_(3)O_(4)的比表面积逐渐增大,氧化还原性能逐渐增强。其中当氧化剂/燃料比为1∶2时所得的Co3O(4命名为Co1CA2)具有最小的晶体尺寸、较高的比表面积。此外,该催化剂不仅具有较好的氧化还原能力,同时表面有更丰富的Co^(2+)以及吸附氧物种,并且此时的Co-O键更容易断裂,意味着可以提供更多的活性氧物种。在低浓度甲烷的催化氧化测试中,Co1CA2表现出了最好的催化活性,其T90值为370℃,相较于直接煅烧硝酸钴得到的Co_(3)O_(4)降低68℃。在经过3次非连续的稳定性测试后,Co1CA2对甲烷的去除率仍旧稳定在90%以上,表现出良好的耐性。

The ratio of oxidant(cobalt nitrate)to fuel(citric acid)in the precursor could exert great influence on the catalytic oxidation of low concentration methane of Co_(3)O_(4),which was prepared by solution combustion synthesis.With the increasing of fuel proportion,the specific surface area of Co_(3)O_(4)and the catalytic performance gradually increased.Among all of the obtained Co_(3)O_(4)samples,the one obtained by setting the oxidant/fuel ratio to be 1∶2(named as Co1CA2)showed the smallest crystal size and higher specific surface area.In addition,the Co1CA2 displayed not only better reducibility,but also a richer surface of Co^(2+)and Oads,and the Co-O bond in this catalyst is more likely to break,which means more reactive oxygen species can be provided and thus would bring benefit to the catalytic activity of Co_(3)O_(4)during the methane oxidation.Therefore,in the catalytic oxidation of low concentrations of methane,Co1CA2 performed the highest catalytic activity with a T90 value of 370℃,which is 68℃lower than the Co_(3)O_(4)obtained by calcining oxidant directly.After three discontinuous stability tests,the removal rate of methane by Co1CA2 was still above 90%,showing good water resistance,repeatability,and durability.