Design Of Cerium-Based Oxygen Storage Catalysts And Research On The Performance Of Chemical Chained Ethylbenzene Oxidative Dehydrogenation

Styrene is one of the most important chemicals in the petrochemical industry and is widely used in the production of polymers.However,the ethylbenzene dehydrogenation process is one of the very important petrochemical raw materials production processes.At present,the industrial ethylbenzene dehydrogenation production process has some unsolved problems,for example,the ethylbenzene dehydrogenation reaction process is limited by thermodynamics,energy consumption is too high,catalyst deactivation,carbon deposition problems,and the selectivity of styrene Lower defects.Therefore,the use of chemical chain ethylbenzene oxidative dehydrogenation technology is an effective way to solve the above problems.The research content of this paper is:the influence of transition metal doping,adjustment of cerium-iron ratio and alkali metal loading on the performance of ethylbenzene oxidative dehydrogenation.First,Ce O₂ is used as a substrate to do（Fe,Mn,Cu,Ni,Co,etc.）transition metal ion doping.Secondly,adjust the ratio of Ce O₂ to transition metal Fe to determine the best ratio of cerium to iron.Third,the alkali metal（Li,Na,K）impregnation screens the best impregnated metal.Finally,the loading of alkali metal K is changed.Through XRD,H₂-TPR,SEM,CO₂-TPD,TEM and other series of characterization of the above catalysts.At the same time,the activity of the catalyst prepared above was evaluated.The above characterization and testing are summarized as follows:The study found that catalysts doped with different transition metals have quite different effects on the performance of ethylbenzene dehydrogenation reaction.Through the comparison of the reaction performance of this series of catalysts,it is found that the Ce-Fe catalyst has the best reaction performance,with an ethylbenzene conversion rate of about 65% and a styrene selectivity of 89%.Finally,it is modified with a catalyst doped with iron.Then,through the activity test,it was found that when the Ce/Fe ratio was 4:1,the conversion of Ce_0.8Fe_0.2O₂ catalyst to ethylbenzene during the reaction was78.2%,and the selectivity of styrene was 93%.Through research,it is found that alkali metal loading can improve the activity of Ce_0.8Fe_0.2O₂ catalyst,and different alkali metal loadings have different effects on catalyst performance.After testing,it was found that the 20wt.%K/Ce_0.8Fe_0.2O₂ catalyst performed best,among which the conversion rate of ethylbenzene was about 85%,and the selectivity of styrene was 92%.The loading of K affects the acid and basic sites of the catalyst.The CO₂-TPD characterization found that as the loading of K increases,the basic sites of the catalyst also increase further,but when the loading of K is 30wt%,The reaction performance is that the best ethylbenzene conversion rate reaches 89.6%,and the styrene selectivity is 93%.Therefore,30wt%K/Ce_0.8Fe_0.2O₂ was used as the research object for 20 cycles stability test.The stability of the catalyst before and after the cycle is very good,and there is no obvious change in the phase of the catalyst.The loading of K affects the acid and basic sites of the catalyst.The CO₂-TPD characterization found that as the loading of K increases,the basic sites of the catalyst also increase further,but when the loading of K is 30wt%,The reaction performance is that the best ethylbenzene conversion rate reaches 89.6%,and the styrene selectivity is93%.Therefore,30wt% K/Ce_0.8Fe_0.2O₂ was used as the research object for 20 cycles stability test.The in-situ infrared test is mainly used to clarify the ethylbenzene oxidative dehydrogenation reaction process:the adsorption of ethylbenzene,the production of styrene,the production of carbonate and the production of water.Among them,the30wt%K/Ce_0.8Fe_0.2O₂ catalyst showed a very obvious trend in the process of ethylbenzene adsorption,styrene production and water production.