Preparation Of Pt/porous Catalyst And Its Application In Catalytic Decomposition Of Formaldehyde In Coatings

In order to make the living and working environment beautiful,people use a variety of materials such as paint,furniture and soft decoration to decorate their houses and offices.Thus,a large number of air pollutants are hidden around us.According to statistics,indoor environmental pollutants mainly contain formaldehyde,volatile organic compounds（VOC）,benzene,ammonia,radon and so on,known as“decoration five poisons”.The formaldehyde is the first of“the five poisons”.In order to get an environmental protection and healthy living environment for people,formaldehyde treatment has become a hot topic that people pay more and more attention to,and the problem of excessive formaldehyde in indoor environment needs to be solved urgently.At present,the methods of formaldehyde treatment are photocatalytic method and chemical reagent reaction method,but it can not be widely used because of the need for certain ultraviolet intensity and chemical reagent toxicity.The catalytic decomposition of formaldehyde by precious metal catalyst supported by porous materials has many advantages,such as high efficiency,no secondary pollution,green and safe reaction process and no illumination reaction conditions.Porous materials have broad application prospects because of their advantages of simple synthesis method,cheap materials and easy availability.This thesis selects different natural and artificial porous materials as the carriers,loading Pt by impregnation.The prepared noble metal catalysts are used to catalytically decompose formaldehyde.A variety of porous materials and structure,composition and morphology characteristics of catalysts were studied in detail.The catalytic activity to formaldehyde in the coating was evaluated.The main research results are as follows:1.Using natural porous materials washed diatomite and calcined diatomite as carriers,after simple pretreatment,Pt/washed diatomite catalyst and Pt/calcined diatomite catalyst were prepared by impregnation method respectively,and added into the coating.The influence of each factor on the catalytic decomposition formaldehyde was studied in detail.By means of transmission electron microscopy（TEM）,X-ray diffraction（XRD）and specific surface area,the mechanism of the different catalytic activity of two kinds of diatomite as carriers after different treatment methods was speculated.The effects of H₂ reduction temperature and Pt loading on the catalytic decomposition ability of formaldehyde were also studied.2.Considering the specific surface area,the source of porous materials and the cost of support,the Silicalite-1 molecular sieve was selected as the support and Pt/Silicalite-1 molecular sieve was synthesized by impregnation method.The influence of specific surface area of Silicalite-1 molecular sieve carrier,Pt loading and morphology on the sizes and dispersion of Pt nanoparticles have been investigated.By changing Pt loading and adding catalyst into the coating,it showed a high catalytic activity to formaldehyde.3.Considering the pore volume,carrier and the source of the porous material cost factors,commercial common synthetic porous materials of 4A molecular sieve were chosen as the carrier,Pt/4A catalyst was prepared by impregnation method.The pore volume,H₂ reduction temperature and synthetic carrier on the influence of particle size and dispersion degree of Pt nanoparticles were studied.It was found that the specific surface area and pore volume of 4A molecular sieve were small,and a small part of Pt particles appeared agglomeration phenomenon.The results of catalytic activity test show that different H₂ reduction temperature and different concentration of Pt loading have great influence on the decomposition performance of formaldehyde.