Highly Dispersed Pt Atom Catalysts Prepared By Reducing A Perovskite-type Oxide Precursor For CO Oxidation

With the development of mankind's industrialization,the emission of CO has increased substantially,and it has caused serious harm to humans and other biological organisms on the earth.Therefore,the control and elimination of CO emissions is imminent.CO oxidation is widely used in various fields as a method for eliminating CO.For example,the elimination of CO at room temperature and atmospheric humidity has a strong practical value in automotive exhaust gas treatment,air purification,sensors,sealing systems?manned space shuttles,nuclear submarines,etc.?and civilian equipment.In addition,as CO oxidation is simple and representative,it is often used as a probe reaction in scientific research.Supported noble metal catalysts are widely used in the industry due to their excellent catalytic properties.The size of the metal particles is an important factor for catalytic activity.In order to increase the utilization and efficiency of precious metal atoms,higher dispersion is worth pursuing.Aiming at the problem that high-dispersion noble metal catalysts are difficult to efficiently produce,a new method for preparing supported high-dispersion catalysts is proposed in this paper.Highly dispersed Pt catalysts were prepared by supported perovskite oxide precursors.Catalysts were characterized by BET,TPR,XRD,TEM,CO-TPD and TOF.CO oxidation was tested as a probe reaction.A series of supported perovskite oxides LaCo_1-xPt_xO₃/SiO₂?x=0.03,0.05,0.07,0.09,0.10?were prepared by the citric acid complex method and the equal volume impregnation method.Pt atoms were reduced at low temperatures.When x<=0.05,the catalysts with the highest Pt dispersion can be obtained.After the activity testing,the catalyst can remove CO completely at lower temperatures?around 230°C?.It can maintain stability at 400°C for 250 h.Considering the preparation scheme,the reason why the catalyst can be highly dispersed and stably exists is:Firstly,the presence of a supported Pt-containing perovskite allows Pt to be uniformly dispersed in the perovskite nanocrystallites at the atomic scale.Secondly,Pt atoms migrate from the interior of the perovskite to the surface after low temperature reduction.The highly dispersed catalyst can be stably present as the strong interaction between the Pt atoms and the perovskite.A series of supported perovskite oxides LaNi_1-xPt_xO₃/SiO₂?x=0.03,0.05,0.07,0.09,0.10?were prepared by the same method.The catalysts were tested after the low temperature reduction.The test results show that the relative activity and stability of the catalysts are the best when x=0.05.The reason why it can exist steadily is similar to the former.In this paper,a highly dispersed Pt atom catalyst was successfully prepared by a simple method.