Study On Novel Hybrid Nano-structure Pt Catalyst For Water Gas Reaction

With the world to coal and oil,methane and other fossil fuels consumption,as well as the environmental pollution and global warming.The search for environmentally sound alternatives has become a top priority.Hydrogen energy is considered to be the most environmentally friendly energy of the future,not only can be stored and transported easily,but also burns without pollution.The water gas shift reaction can be used to treat industrial waste gas containing CO or to produce hydrogen for use without causing pollution to the environment.The industrial water gas shift reaction（WGSR）generally adopts the"two-stage method",the first stage is the high temperature transformation reaction（HTS）stage,the catalyst is generally Fe-Cr high temperature catalyst;The second stage is the low temperature transformation reaction（LTS）stage,and the catalyst is Cu-Zn-Al.The two-stage method is generally applicable to large industrial reaction units,but it has some disadvantages.Fe-Cr catalyst contains Cr highly toxic substances,large use is not environmental protection.Cu-Zn-Al catalyst is prone to poisoning and deactivation,which requires frequent replacement of the catalyst.It is also difficult to preserve and has poor stability.With the development of hydrogen energy industry needs to explore a new type of efficient catalyst is the key problem to improve the conversion rate of water gas shift reaction.In this paper,we propose a strategy to prepare a novel hybrid nano-structure Pt catalyst by anchoring nano-noble metal Pt on semiconductor film.According to the principle of spontaneous monolayer dispersion,SBA-15 was coated with CeO₂ and ZrO₂ in monolayer or multilayer dispersion by impregnation method,and TiO₂was also coated with CeO₂ dispersion.Composite support CeO₂/SBA-15,ZrO₂/SBA-15 and CeO₂/TiO₂ were prepared,and then Pt nanoparticles were anchored on the composite support coated with semiconductor film by photochemical reduction method.Three catalysts,Pt/@-Me O_x/SBA-15（Me O_x:CeO₂ or ZrO₂）and Pt/@-CeO₂/TiO₂,were prep-ared and characterized by XRD,TEM and N₂ adsorption-desorption methods.The res-ults showed that the catalysts had special interfacial electronic effects.Pt nanoparticles loaded with small particle size and good dispersion.The catalytic performance of the catalyst under various water gas reaction conditions was systematically investigated.The CO conversion rate of 2%Pt/@-10%ZrO₂/SBA-15 can reach 99.92%under the conditions of pretreatment temperature350^oC,pretreatment time 2h,20%H₂/80%N₂,water vapor ratio V（CO）:V（H2O）=1:8,and reaction temperature up to 320^oC.When the reaction temperature is 320^oC,the conversion of 2%Pt/@-10%CeO₂/SBA-15 can reach 100%CO.Under the conditions of pretreatment temperature 300^oC,time 2h,20%H₂/80%N₂,water vapor ratio V（C-O）:V（H₂O）=1:4,and reaction temperature up to 275^oC,0.5%Pt/@-15%CeO₂/TiO₂ can reach 100%CO conversion.Compared with traditional supported Pt catalysts（Pt/ZrO₂,Pt/CeO₂,Pt/TiO₂ and Pt/SBA-15,etc.）,the catalytic activity of the catalysts with this structure is significantly better because of the special electronic effect on the surface,and it can be maintained for a long time without deactivation.