用于NO_x低温下吸附还原的CoO_x/CeO_2二元氧化物的制备

研究了以多孔二氧化硅微球和活性炭为载体制备NOx吸附/还原催化剂的方法,摸索了最佳Ce/Co物质的量的比例。采用低温氮吸附方法测定了样品的BET比表面和孔容,利用XRD方法表征了样品中所掺杂的金属元素的晶型。研究发现:当nCe/nCo=75/25时,材料获得最佳NOx吸附能力,当以多孔二氧化硅微球作载体时,材料对于NOx的吸附主要来自CoOx和CeO2的二元氧化物;当以活性炭作为载体时,活性炭参与了NOx的吸附,因此其吸附容量大大提高。对NOx的吸附机理进行了探讨,并研究了样品的NH3还原性质。

Preparation of CoOx/CeO2 Binary Oxides for NOx Storage and Reduction at Low Temperature

The preparation of NO_x storage and reduction catalyst using porous silica bead and active carbon as the support was studied. The optimized molar ratio of Co to Ce was obtained. The low temperature nitrogen adsorp-desorption was employed to measure the surface area and pore volume of the samples. The crystal structure of the metal element in the catalyst was investigated by XRD analysis.The results indicate that the best NO_x adsorption performance is achieved when the n_Ce/n_Co=75/25. When porous silica sphere is utilized as the support, the NO_x is mainly adsorbed by the binary oxide composed of CoO_x and CeO₂; however, when the active carbon is used as the support, it makes obvious contribution in NO_x adsorption, as a result, the NO_x adsorption capacity of the sample is greatly increased. An adsorption mechanism upon NO_x is also proposed and the NH₃ reduction behavior of the sample was investigated.