Analysis On Key Factors Of Methanol Catalyst Deactivation And Study On Preparation Of Sulfur Tolerant Catalyst

Methanol is an extremely important basic chemical raw material,mainly used for the production of dimethyl ether,gasoline,formaldehyde,etc.,and can also be used as a potential vehicle fuel alcohol alcohol fuel,methanol plant growth promoter.In this process,the catalyst is the key.However,at present,the service life of corporate catalysts generally reaches only about 1/3 of the designed life of catalyst manufacturers,which seriously increases the operating costs of the company.Therefore,finding the key cause of catalyst deactivation and proposing a solution with practical application value are the key issues that enterprises need to solve urgently.In response to this problem,this article starts with the composition and content of syngas and catalyst deactivation factors.With the help of XRF,XRD,BET,XPS and other means,the element content,particle size,and Dispersion degree,distribution mode,etc.,to determine the influence of synthesis gas composition and content on the physical and chemical properties of the catalyst,and provide a theoretical basis for the subsequent selection and development of the catalyst.The specific research contents are as follows:Study the key factors of catalyst deactivation.Characterization and analysis of the composition and content of impurities S,Cl,Fe,etc.on the used old and new methanol catalysts,the active components CuO/Cu,the size and distribution of the nanoparticles of the additive ZnO/Zn since normal operation.The results show that the new catalyst contains a very small amount of Fe,Ni and other elements,and does not contain S and Cl.However,new impurities S and Cl were produced on the catalyst after use,and the Fe content was significantly higher than that of the new catalyst.From the top of the tower to the kettle,the S and Cl contents on the catalyst gradually decrease after use,and the Fe content increases first and then decreases.A very small amount of S,Cl and Fe on the catalyst is a major cause of catalyst poisoning and deactivation.Study the reaction mechanism of syngas to methanol.Using the micro-reaction process of in-situ infrared on-line synthesis gas to methanol,the influence law of synthesis gas impurity components on the methanol synthesis reaction mechanism was determined.The results show that HCOO-Zn is a key intermediate in the synthesis of methanol,and the rate-limiting step in methanol synthesis is the hydroxylation of CH3O-Zn.In the reduction process of the enterprise catalyst,not only the reduction of CuO is carried out,but also the reaction of CO₂ and H₂ on the surface of the catalyst.During the reaction,the carbonate species are first hydrogenated to form formate species,and then hydrogenated to form Methoxy species,and finally methanol.The presence of poisons in the micro-reaction of syngas to methanol hinders the formation of formate intermediates,leading to the disappearance of hydroxy species and finally affecting the formation of methanol.The effect of the addition of cerium oxide on the catalytic performance of copper,zinc and aluminum catalysts in enterprises was studied.Co-precipitation method was used to prepare CZCA catalyst.In a fixed-bed reactor?5 MPa?,CO conversion and methanol selectivity were measured by gas chromatography.The results show that the catalytic performance of the catalyst CZCA is even better,with CO conversion,methanol selectivity and methanol space-time yield STY reaching 15%,89.37%and0.17g MeOH h^-1gcat^-1,respectively.After 8 hours of H₂S poisoning,the percentage of CO conversion in the catalyst of the enterprise decreased by about 46%,and the selectivity of methanol decreased by about 14.3%.However,under the condition of H₂S poisoning on the CZCA catalyst for 8 hours,the CO conversion rate decreased by about 29.3%,and the methanol selectivity decreased by about 9.6%.Therefore,the sulfur resistance of the CZCA catalyst was slightly better than that of the enterprise catalyst.