Preparation Of La-Ce-Mn Catalysts And V-W-Mn-Ti Catalysts And Research Of Their Nature In The Catalytic Combustion Of Chlorobenzene

Chlorinated volatile organic compounds （CVOCs） are hazardous pollutants, thesafe disposal of CVOCs pollutants has acquired great importance with the everincreasing concern for environmental protections. So far as we know, the catalyticoxidation of CVOCs is the best method for their degradation. The main results are likethe followings:1. A series of catalysts of different manganese and vanadium loading content ofMnO_x-VO_x-WO_x/TiO₂（MnVW/Ti） were prepared by wet-impregnation method usingnano-size TiO₂as support. Chlorobenzene（CB） was chosen as a model compound toevaluate the catalytic activity in a conventional fixed-bed quartz reactor. The catalystswere characterized by transmission electron microscopy（TEM）, X-raydiffraction（XRD）, H₂temperature-programmed reduction（H₂-TPR）. The resultsshowed that a certain amount of V、W were completely dispersed on the surface ofanatase TiO₂. When a small quantity of Vanadium was replaced by manganese （Mn/V=1/3, molar ratio） of MnVW/Ti catalyst, low and middle temperature catalyticactivity could be improved compared with VW/Ti catalysts in the catalyticcombustion of chlorobenzene because of excellent low temperature catalytic activityof manganese, but high temperature catalytic activity decreased. The tungsten couldreact with vanadium and generate highly active species, but manganese did not havethis property. That result in reduction of high temperature catalytic activity, when alarge amount of Vanadium was replaced by manganese （Mn/V=1/1、3/1）.2. CeMn and LaCeMn were prepared by the co-precipitation method.La wassupported on CeMn by the deposition-precipitation method,and its catalytic activityfor chlorobenzene oxidation was tested.The results showed that doping La in CeMncould improve its catalytic activity for chlorobenzene oxidation.The analyses of X-raydiffraction，temperature-programmed reduction further showed that the presence of Lain CeMn not only restrained the growth of CeO₂crystallites and ehhanced themicrostrain of CeO₂, but could also suggest the Mn ions incorporation in the CeO₂lattice to form a homogeneous Ce-Mn-O solid solution.The results of catalyst thermalstability test illustrated that doping La in CeMn could improve its thermal stability.