Novel Noble Metal Catalyst Via Ce/Mn Doping For Low Temperature Actone Catalytic Oxidation

Volatile organic compounds（VOCs）is one of the main air pollutants,which is an important precursor that can lead to photochemical smog and ozone hole.It is severely harmful to human health and living environment.Acetone as the typical VOCs,is mainly generated from the pharmaceutical and chemical industry.However,compared to carcinogenic VOCs（e.g.benzene and toluene）,acetone has not attracted public attention.Low temperature catalytic oxidation is a main technology to eliminate VOCs and the core of this technology is to develop high efficent low-temperature catalyst.The noble metal catalyst,with good low-temperature activity,high selectivity,thermal stability and other excellent characteristics,has attracted more attention.In this research,we prepared two novel catalysts（i.e.PtCe/TiO₂ and PdMn/TiO₂）for acetone oxidation.XRD,TEM,TPR,XPS and other tests were used to characterize the synthetized catalysts.The physicochemical properties,the catalyst structure and surface element valence state were analyzed to illustrate the relationship between structure and performance.The catalysts with and without additives（Ce and Mn）were analyzed and compared to speculate the catalytic oxidation mechanism.The main conclusions are listed as follows:（1）Novel catalysts with different proportion of noble metal/additives were prepared.Acetone,as a probe reactant,was used to test the catalytic oxidation performance.The results showed that the Pt_0.01Ce_0.2/TiO₂ displayed the optimal catalytic performance with the conversion temperature of T₅₀ and T₉₅ at 200℃ and237℃.The main products were H₂O and CO₂ without other impurity by-products.The characterization results indicated that the catalyst added Ce presented a higher Pt⁰ ratio as well as an intensified bond between carrier and active components.The alloy particles can be evenly distributed on the surface of the carrier.（2）Except Pt catalysts,performance of Pd catalyst for acetone has also been studied.The results demonstrated that the Pd_0.01Mn_0.2/TiO₂ showed the optimal catalytic performance with the conversion temperature of T₅₀ and T₉₅ at 219℃ and 276℃.Meanwhile,the addition of Mn increased the Pd⁰ content in the catalyst,which proved that valence of noble metal particles is an important factor affecting the catalytic activity.（3）To verify the influence of metal state,comparative study of the catalytic performance of modified Pt and Pd based catalyst after H₂ pretreatment were carried out.The experiment result indirectly verified that metal state of noble metal particles were the main active species.Through the observation of valence changing on the surface of the catalyst via XPS and the reaction between active component and the support function via TPR,it can be concluded that the preliminary mechanism of acetone catalytic oxidation is in accordance with MVK mechanism.In addition,the catalyst stability test showed that the catalytic activity could last for more than 48 h.