过渡金属改性OMS-2催化燃烧二氯甲烷性能研究

Catalytic combustion dichloromethane on OMS-2 with different transition metals doped

本文以DCM催化燃烧为模型反应,研究了Sr、Cr、Ce、V四种不同过渡金属掺杂的隐钾锰矿型MnO2(OMS-2)对其的催化燃烧活性和产物选择性,并通过XRD,N2-吸脱附,HR-TEM以及Raman光谱进行了系列表征。结果显示,Cr掺杂OMS-2对DCM有良好的催化燃烧活性和HCl选择性,且能显著抑制TCM和CTC多氯副产物的生成,而DCM在Sr,Ce和V掺杂的OMS-2上转化时,会生成一定量的多氯副产物。Raman光谱分析显示Cr掺杂增大了OMS-2上的氧空位缺陷浓度,对气相氧的吸附和交换更加容易,因此对DCM有优良的低温燃烧活性和HCl选择性。

Four different types of transition metals(Sr,Cr,Ce,and V)doped manganese oxide octahedral sieves(OMS-2)were prepared by one-step reflux heating method and used in dichloromethane(DCM)combustion.Their physicochemical properties were investigated in detail by X-ray diffraction,N2-physisorption,high-resolution transmission electron microscopy,and Raman spectroscopy analyses.The results showed that DCM could be completely converted between 150℃and 450℃on these investigated catalysts,and the main chlorinated products were HCl,trichloromethane(TCM),carbon tetrachloride(CTC)and also a little amount of Cl2 aroused from Deacon reaction.However,their relative activity and the products selectivity were far from identical.The high selectivity of HCl was observed when DCM combustion on the Cr doped OMS-2,meanwhile,the polychlorinated byproducts such as TCM and CTC were deeply restrained.On the contrary,these troublesome byproducts generated easily when DCM converted on the other OMS-2 doped with Sr,Ce and V.The high oxygen vacancy defects concentration on the Cr doped OMS-2 benefited the adsorption and exchange of oxygen from air as confirmed by Raman spectroscopy analyses,thus,this sample showed excellent low-temperature combustion activity and good HCl selectivity when DCM combustion on it.