Selective Hydrogenation Of 1,3-butadiene On Au/SBA-15 Catalysts

C4 hydrocarbons are important chemical resources,being produced from such technologies as catalytic cracking,steam cracking and methanol to olefins.C4components are mixtures and the relative volatility of the products is very close,indicating that they are not easy to be separated.The separated 1-butylene product always contents about 0.5%of butadiene using the traditional separation methods such as acetonitrile,dimethyl formamide and N-methyl pyrrolidone.Further separation is not worthy,so catalytic hydrogenation of butadiene is a more effective method.The specific conclusions are as follows:?1?In this thesis,a serious of catalysts with same content of Au based on the Si O₂?Ti O₂and Al₂O₃were researched for the selective hydrogenation of butadiene.It was found that Au/Si O₂catalyst had better conversion of the selective hydrogenation of butadiene,which was about 10%.And during the process,the amount of each product was stable on the Au/Si O₂catalyst.By deeper research of the different mesoporous structures carrier,it was found that 1%Au/SBA-15 catalyst had an excellent catalytic activity,for the conversion was up to 25%and the selectivity of the single product n-butene can be above 65%.Therefore,the mesoporous SBA-15prepared by template method was selected as the carrier in this thesis.?2?This thesis used the method of template preparation to produce the catalyst carrier of mesoporous silica SBA-15.A serious of Au/SBA-15,Ag/SBA-15 and Cu/SBA-15 catalysts were produced by impregnation method to study the catalytic behavior in the reaction of butadiene hydrogenation.Used the testing method of gas chromatography,DRIFT,BET,SEM,TEM and XPS,Au/SBA-15,Ag/SBA-15 and Cu/SBA-15 catalysts of the same contents and Au/SBA-15 with different contents are investigated.The result showed that the catalyst carrier of mesoporous silica SBA-15can effectively disperse metal active components because of the large specific surface area.Among these different kind of metal-based catalysts,3%of Au/SBA-15 catalyst has the best catalytic activity.Specifically,it has the highest conversion rate at the same temperature.The selectivity of n-butene can reach to 60%and the selectivity of butane is lower than 5%.?3?Comparing the catalytic performance of the different contents of Au/SBA-15catalysts,it is found that 3%Au/SBA-15 has the best catalytic activity than the 1%Au/SBA-15 and 5%Au/SBA-15 catalysts with little difference in selectivity at the same temperature.For the characterization of these catalysts,it can be seen from the TEM and SEM figures that 3%Au/SBA-15 catalyst is dispersed more evenly than other catalysts,so the catalyst has the best catalytic activity.According to the DRIFTs of Au/SBA-15 catalyst,the hydrogenation reaction is easy to happen because of the low energy barriers for butadiene selective hydrogenation which are 20 k J mol^-1,17 k J mol^-1,55 k J mol^-1,20 k J mol^-1,respectively.It can be seen that adding the third H has the highest energy barriers,resulting in it be the speed-control step,so the selectivity of butane is good.