Insight into the effect of manganese substitution on mesoporous hollow spinel cobalt oxides for catalytic oxidation of toluene
Insight into the effect of manganese substitution on mesoporous hollow spinel cobalt oxides for catalytic oxidation of toluene
复制标题
深入探讨锰取代对介孔空心尖晶石钴氧化物催化氧化甲苯的影响
DOI：
10.1016/j.jcis.2021.03.093
复制
发表时间：
2021
影响因子：
9.9
通讯作者：
Daiqi Ye
中科院分区：
文献类型：
--
作者：
Peng Liu;Yuxi Liao;Jingjing Li;Longwen Chen;Mingli Fu;Puqiu Wu;Runliang Zhu;Xiaoliang Liang;Tianli Wu;Daiqi Ye
The cobalt oxides and manganese oxides have high-activity potential for catalytic oxidation of volatile organic compounds (VOCs), while the mesoporous hollow morphology is crucial to the mass transfer of reactant and product. Therefore, it is worth investigating the effect of manganese substitution in mesoporous hollow cobalt oxides on catalytic oxidation. Herein, a partially disordered spinel structure is formed by the Mn substitution in Co3O4and the mesoporous hollow microsphere is improved in morphology homogeneity with the decrease of Co/Mn ratio in the range of 1.8–28.8. The 5Co1Mn (Mn-substituted Co3O4with Co/Mn at 5.4) exhibits outstanding catalytic activity for toluene oxidation with 50% CO2generation at 237 °C, which is 21 °C lower than Co3O4. Moreover, the 5Co1Mn displays satisfactory stability in reusability, lifetime, and water resistance. The small defective crystallite, mesoporous hollow morphology, and high specific surface area endow Mn-substituted Co3O4with more surface chemical adsorbed oxygen, enhancing the catalytic oxidation of toluene. Theoretical calculation on (3 1 1) plane of Co3O4reveals that Mn2+or Mn3+substitution increases the formation energy of oxygen vacancy and makes it difficult to adsorb gaseous oxygen on the defective surface. The interaction between Co and Mn impedes the improvement of toluene oxidation because the mobility of lattice oxygen, the surface distribution of Co3+, and the ratio of surface adsorbed oxygen to surface lattice oxygen are hindered by Mn substitution. The chemical adsorbed oxygen is more active than lattice oxygen in the oxidation of adsorbed intermediates (phenolate, benzoate species, etc.). The Langmuir-Hinshelwood mechanism dominates in the catalytic oxidation at 200–250 °C, while the catalytic oxidation follows both the Langmuir-Hinshelwood mechanism and Mars-van Krevelen mechanism above 250 °C. This work provides some enlightenment for exploring the role of surface oxygen species in VOCs oxidation and uncovering the interaction in binary spinel oxides.
