Preparation Of Pt/SDB Catalyst And Study On The Mechanism Of Surface Residual Double Bond

The prospect of the use of nuclear energy lies in its ability to replace fossil fuels on a large scale and reduce environmental pollution.With the rapid development of the nuclear industry and the establishment of various types of nuclear reactors and nuclear power plants,large amounts of heavy water are generated every year.Although the current PWR nuclear power plant has a low level of thorium,the amount of waste water is extremely large.Life-producing brings great harm,so the discharge of waste water containing rubids need to be solved urgently.Hydrogen-water exchange reaction is an effective hydrogen isotope separation route.With a high separation factor,process equipment is relatively simple,and it has a very wide range of application prospects in the development and utilization of nuclear energy.In this paper,styrene-divinylbenzene(SDB)carrier,Pt/SDB catalyst and Pt/SDB/CC catalyst were prepared.The carrier and catalysts were characterized and analyzed.The hydrogen isotope exchange reaction was performed in a gas-steam paralled flow test using a laboratory hydrogen-deuterium catalyst exchange apparatus.The results showed that the physical properties of the SDB carrier prepared by the mixed porogen toluene and isooctanol were better.The addition of the linear oligomer polypropylene glycol(PPG)as the porogen can increase the average pore size.Introduction of carbon tetrachloride as a porogen can increase the content of suspended double bonds in the carrie.The addition of initiator benzoyl peroxide(BPO)can increase the content of carrier suspended double bonds.But the use of equal mass azoisobutyronitrile(AIBN)and BPO together as the initiator physical parameters and carrier forming effect are better.Compared with liquid-phase reduction of Pt/SDB catalyst,the catalyst activity obtained by gas phase reduction is very high,and the platinum particle size is small and evenly distributed and a small amount of agglomeration occurs.When the quality of the hydrophilic filler and catalyst are used as a catalyst,the catalyst activity is higher.Increasing temperature and hydrogen flow rate can improve the activity of all catalyst.In addition,the life of the prepared Pt/SDB catalyst was tested,the H-D exchange rate reduced by about 12% for 150 days.The results can basically meet the industrial requirement.For Pt/SDB/CC catalysts,the straight channel structure of cordierite ceramics provides more reaction sites for hydrogen isotope exchange experiments.When facilitates reactions at low hydrogen flow rates(less than 100 mL/min),the hydrophilic filler of the same mass as the catalyst is added in a wrap-around manner,so that the catalyst activity is better.And at high hydrogen flow rates(greater than 100 mL/min),the catalyst without hydrophilic filler show better activity.After carrying out the tableting infrared and titration analysis on different double bond content carriers,it was found that when the amount of double bonds is more,the more double bond-platinum are formed.The double bond platinum is more conducive to hydrogen isotope exchange reaction than benzene-platinum.Different loadings for the same load carrier,the proportion of double bond platinum is increased when increasing platinum content,platinum is more selective for suspended double bonds.