Controlled Synthesis Of Silver Based Catalyst And Research Into Catalysis Reactions

As one of the most commonly used catalyst material,silver based materials has been widely used into the area of electrochemical catalysis reactions,industrial catalysis reactions and also environmental catalysis reactions,etc.It has been widely used into large scale use and also industrialization,for the superior performance,low cost and also good stability.P-nitrophenol,as a pollutant in waste water,has caused several severe problems,such as water pollution.And also,the problem of water pollution not only has a great influence on agricultural products,but makes a great threaten to human health.In industry,to deal with the pollutant of p-nitrophenol,except for physical method and biological method,for example,the physical adsorption or organisms to deal with p-nitrophenol directly,meanwhile,the chemical methods to deal with p-nitrophenol is still widely used today,for low cost and high effiency.When using chemical methods to deal with the problem of the reduction of pnitrophenol,it should be attached strong attention that,when using sodium borohydride as reducing agent,using silver based material as catalyst to promote the reaction.In this thesis,we use traditional imprgnation method to prepare a series of silver based catalyst samples,mainly adjusting the silver particle size,suface valence state and also other element addition and the influence of support to the silver particles.It provides with us a new strategy to prepare silver based catalyst with variation of regulation and addition to the reduction of p-nitrophenol.The mainly research content is as follows:(1)By adjusting the calcination conditions,we can easily regulate the particle size of silver partilces supported on aluminum oxide support.We adapted mainly the strategy of varying the calcination time and calcination temperature.When adapting the method of varing the calcination time to tune the particle size,we can find it’s really hard to tune the electron on the surface of silver,the variation of the performance to the reduction of pnitrophenol mainly comes from bigger particle size,for negative effect on adsorption of reactant,the bigger the silver particle size,the worse performance the particle will be.Then adapting the method of varing the calcination temperature,when the temperature rises,the particle size of silver particles will not only turn bigger,but the surface valence state will also rise as well.Now,the electron effect will turn to be effective;(2)Aluminum oxide is oftern used as support in the petrochemical industry.Here,the reduction reaction of p-nitrophenol was investigated here,with promotion effect of promoters.We consider to use promoter of Cu,Cs and Re,also their loading weight,to further consider their influence on the reduction reaction and also the catalysis mechanism.By the variation of loading weight,the three promoters of Cu,Cs and Re appears different effect on tuning the surface electron state,and also there are optimize loading ranges.When locating in the optimize loading weight of the promoters,the valence state of silver will turn to be a higher one,which will promoter the reaction of the reduction of p-nitrophenol.Also,we also inverstigate the inner reason of the promotion effect of different promoters,we can find out that the promoter can absolutely effect the adsorption and desorption ability of oxygen of silver particles;(3)When using aluminum oxide,carbon,silicon oxide,ceric oxide and titanium oxide to be as the supports in the investigation,we further investigate the influence of different support to the catalysis reaction of the reduction of p-nitrophenol.We can obviously discover that,when it has a large BET surface area of a support,the performance of the catalyst to the reaction of the reduction of p-nitrophenol will have a positive promotion.Otherwise,the bigger BET surface area will have a positive effect on the dispersion of silver particles,and furthermore,it will have a small particle size.While,the smaller size of silver particles will promote the performance of the catalyst.What’s more,the acidity of the support will also have a huge influence on the performance of the catalyst.The alkalinity oxide will have a negative influence on the reduction of pnitrophenol,while the acid oxide and amphoteric oxide will have nearly no influence on the reduction reaction.Meanwhile,the negative effect of alkalinity oxide will take the main place.