The Synthesis And Research Of MCM-49 Zeolites

In this experiment,MCM-49 zeolites were synthesized to investigate some factors on the mode of action and action mechanism of MCM-49 zeolite.Around related issues,a series of experimental methods and characterization analysis were used to achieve the purpose of the experiment.MCM-49 zeolite samples with high purity was synthesized in the experiment.In this paper selects the liquid silica sol as silicon source,using HMI as a single template agent,according to a certain proportion by gel,dynamic hydrothermal synthesis of MCM-49 zeolite samples,after the crystallization of the product by cooling,multiple filtration to neutral and got MCM-49 powder.Then after the muffle furnace roasting with ammonium nitrate solution is acidified finally got white powder of HMCM-49,the subsequent processing of zeolite samples through a series of characterization were determined the MCM-49 zeolite with high purity.In addition,some factors which affect the crystallization process of zeolite,such as its morphology,structure and acidity distribution,were studied in this paper.(1)The effect of template agent content: with the increase of HMI content,the crystallinity is getting bigger,when the molar ratio of HMI and silica was 0.35,samples obtained the maximum crystallinity.When the content of HMI was more than 0.35,the crystallinity decreased,but the SBET calculated by BET has been on rise,the catalytic activity of the surface increases gradually.This study can be used to control the amount of template agent to achieve the purpose of saving production costs and improving the catalytic activity of zeolite.(2)The effect of crystallization time: through a series of experiments to control the crystallization time then formation and growth of MCM-49 grainsduring the crystallization process can be obtained.When crystallization started,the system was mainly presented in the amorphous state,with the deepening of the hydrothermal synthesis,crystal size of MCM-49 zeolite was increasing,after 72 h dynamic heating system,almost all of the system was MCM-49,and then increase the heating time,the system with misoriented grain,this study provides the basis for the shorten the synthesis time of zeolite.(3)The effect of crystal seed: by adding a little amount of MCM-49 in the crystallization process of the product as a kind of homogeneous crystal,it can obviously accelerate the crystallization process of the zeolite,increase the crystallinity and reduce the formation of the misoriented grain.Its practical significance lies in shortening the synthesis cycle of the zeolite,solving the problem of long time of synthesis of the traditional zeolites,saving the production costs and improving the synthesis efficiency.(4)The grain size effect of silicon sol: using silica sol with different particle size for experiments,due to crystal size into raw materials required for the nucleation and growth process will inevitably affect the size of the final product crystals,which affects the whole system of the crystallization of zeolite synthesis,so the research on the grain size of silica sol and its great significance...