Optimization Of Amplification Process Of PI-MCM-22 Molecular Sieve And Study On Catalyst Forming Process

MCM-22 molecular sieve has a unique supercage structure,which makes it have the unique advantages of high selectivity,not easy deactivation and long service life in the field of industrial catalysis.It has been widely used in alkylation of benzene with ethylene and propylene to produce alkylbenzene.At present,the highly toxic hexamethyleneimine is used as the template for the synthesis of pure phase MCM-22 molecular sieve in industry.In order to improve this shortcoming,researchers have made many attempts,such as using ionic liquid template,cyclohexylamine and hexamethyleneimine mixed template,etc.Although some achievements have been achieved,there is no industrial report.The research group has explored the process conditions of synthesis of MCM-22 molecular sieve using piperidine as template and made some progress.Based on the previous research of the research group,the synthesis process of MCM-22 was scaled up and the synthesis conditions of the scale-up reactor were optimized.Then,using MCM-22 molecular sieve synthesized in the scale-up reactor as raw material,the strip MCM-22 catalyst was prepared by extrusion molding method,The effect of molding process on the performance of formed catalyst was investigated;the difference of catalyst properties between hydrogen MCM-22 molecular sieve and ammonium MCM-22 was compared,and the optimized molding conditions were obtained;finally,the long-term reaction evaluation of the prepared strip MCM-22 catalyst was carried out.The results of synthesis study of amplification reactor show that the mass transfer and heat transfer of MCM-22 molecular sieve synthesized in 1000 m L and2000 m L scale-up reactors are different from that in 100 m L small reactor;pure MCM-22 molecular sieve can be obtained by dynamic crystallization method and static crystallization method,and the effect is better when the stirring speed is less than 100 r/min by dynamic crystallization method;the effect is better when the stirring speed is less than 100 r/min by scale-up reverse crystallization method In the reactor,crystallization temperature and crystallization time are still the most important synthesis conditions.In this study,the optimal crystallization condition is 150 ℃crystallization for 3 days.If the crystallization time is too short,incomplete crystallization will occur,and if the crystallization time is too long,the phenomenon of crystal transformation will appear.The agitator form in the scale-up reactor has little effect on the crystallization of molecular sieve,and the main purpose of stirring is to make the crystallization mother liquor heat and mass transfer uniform.The results of catalyst forming conditions show that different kinds of binders have little effect on the activity of the formed catalyst;the amount of binder has a certain effect on the properties of the catalyst.The amount of binder is small,the activity of the catalyst is high but the mechanical strength is low;the amount of binder is large,the activity of the catalyst is low but the mechanical strength is high The results show that the mass ratio of raw powder to binder is about 7:3;the type of glue solvent has a certain influence on the properties of the catalyst;oxalic acid and acetic acid can up regulate the structure and acidity of the nodal pore to a certain extent,and improve the conversion of ethylene,but their glue solubility is poor;the catalyst prepared with nitric acid as glue solvent has better mechanical strength,but the conversion of ethylene is slightly lower;the addition of nitric acid has a certain influence on the acidity of the catalyst The results show that the pore structure and acidity of the catalyst prepared from H-MCM-22 and ammonium MCM-22 are changed to some extent,which is more suitable for the alkylation of benzene with ethylene Better catalytic activity.The MCM-22 catalyst prepared in this study is used for alkylation of benzene and ethylene.The one-way ethylene conversion rate is nearly 90%,and the selectivity of ethylbenzene is more than 80%.The catalytic performance of MCM-22 catalyst is basically consistent with that of imported industrial catalysts.Finally,the long period evaluation of the formed strip catalyst was carried out in three-stage reactor series.After 348 h of reaction,the conversion and selectivity of the catalyst did not significantly decrease,which indicated that the indicators of the MCM-22 molecular sieve prepared in this study basically met the requirements of industrial application,and further promoted its industrial application process.