介孔片状NiO/Co_(3)O_(4)催化剂催化碳烟燃烧性能研究

Research on Enhanced catalytic soot combustion performance over NiO/Co_(3)O_(4)within mesoporous nanosheets

采用水热结合等体积浸渍法制备一系列NiO/Co_(3)O_(4)介孔纳米片催化剂,并以柴油机碳烟催化燃烧为模型反应评价其催化性能.研究表明,当Ni/Co物质的量比为12%时,所制备的催化剂12NiCo具有最佳碳烟颗粒催化燃烧活性,其Tm为347℃,CO_(2)选择性为100%,主要归因于以下原因:1)二维片状结构及其较高的比表面积有效增大了催化剂与碳烟颗粒的接触界面;2)纳米片具有丰富的介孔孔道,有利于降低传质阻力,进而促进气体反应物的吸附与扩散;3)NiO的引入增强了催化剂的氧化还原能力,促进了氧物种的吸附与活化生成活性氧物种,同时也促进了NO氧化形成氧化能力更强的NO2参与反应,进一步提升催化活性.此外,该催化剂12NiCo具有良好的循环使用性能,显示了一定的潜在实用价值.

A series of NiO/Co_(3)O_(4)catalysts within mesoporous nanosheets,synthesized by a facile hydrothermal combining wet-impregnation route,have been developed to catalyze diesel soot combustion.Results attest that,when the molar ratio of Ni/Co reached 12%,the catalyst of 12NiCo exhibited the optimal catalytic soot combustion performance,giving Tm of 347℃and 100%CO_(2 )selectivity,which can be chiefly credited to the synergetic effect of the following factors.Firstly,the unique 2D nanosheets together with high surface area enlarged the contact interface of catalyst-soot particles.Secondly,abundant mesopores within nanosheets favored the significant decrease in mass transfer resistance and then in turn promoted the adsorption and diffusion of gas reactants.Thirdly,the enhanced reducibility by introducing NiO not merely facilitated the adsorption and activation of oxygen species to form active oxygen species,but also benefited NO oxidation to produce NO2 with higher oxidative capability,thereby improving catalytic soot combustion performance remarkably.In addition,12NiCo also presented the excellent reusability,demonstrating good potential in future practical applications.