焙烧温度对Ni/MgO催化剂结构及其在甲苯二氧化碳重整反应中催化性能的影响(英文)

考察了焙烧温度对 Ni/MgO 催化剂结构及其在甲苯二氧化碳重整反应中催化性能的影响. 由于 NiO-MgO 固溶体的形成,样品的 X 射线衍射谱中没有出现明显的 NiO 衍射峰, 而在拉曼光谱中出现明显的散射信号. X 射线光电子能谱、氢气程序升温还原和 H2脉冲吸附结果表明, 高温焙烧过程中 Ni 向催化剂体相扩散, 与 MgO 发生强互相互作用, 使得 Ni 物种难以还原,但部分位于催化剂表面的 Ni 物种能够还原; 高温焙烧后催化剂表面活性 Ni 物种明显减少, 致使催化剂重整活性降低. 重整反应后, 催化剂表面存在少量多核芳烃类积炭, 这很可能是高温焙烧催化剂稳定性差的原因.

Effect of Calcination Temperature on Characteristics and Performance of Ni/MgO Catalyst for CO2 Reforming of Toluene

A Ni/MgO catalyst for CO2 reforming of toluene was prepared by impregnating MgO with Ni(NO3) 2.During calcination,some of the NiO diffused into the MgO and formed a solid solution structure of NiO-MgO,which was analyzed by Raman spectroscopy.In the temperature-programmed reduction with hydrogen analysis,only a small part of the Ni species in the outermost layer was reduced to metallic Ni at 700℃.The calcination temperature played a key role in determining the subsequent catalytic activity of Ni/MgO,consequently the catalyst calcined at 600℃ had the highest activity.This catalyst also had the highest surface concentration of reduced Ni,which probably accounted for its high activity.During the reforming tests,a small amount of coke was deposited on Ni/MgO catalyst.Polyaromatic compounds were observed by Raman spectroscopy.The coke was probably responsible for the activity loss of Ni/MgO.