Synthesis And Catalytic Properties Of Micro-mesoporous Zeolites

Micro-mesoporous zeolites has attracted widely attention in potential applications, itcombines advantags of mesopore structure with strong acidity and high hydrothermalstability of micropore structure, and it has large specific surface area. Many scientists areworking on exploring new synthetic methods in order to optimize the bimodal porousstructure, increase the specific surface area, enhance its surface acidity and its hydrothermalstability. This paper synthesized micro-mesoporous zeolites ZSM-5 with a new method andsynthesized different size of PMMA as template agent to synthesize micro-mesoporousmolecular sieve Beta, we also investigated the catalytic properties of the two kinds ofmicro-mesoporous zeolites in catalytic reactions.We successfully synthesized micro-mesoporous zeolites ZSM-5 using TEAOH andCTAB as template agents, adding ethanol as assisted-template agent in this paper. The effectof synthesis mode, synthesis time, synthesis temperature, different templates and theconcentration of the templates to the as-synthesized zeolites’ structure and morphology wasdiscussed in the paper too. The results showed that: the micro-mesoporous zeolites ZSM-5had multi-level pore structure and strong thermal stability. Its BET surface area was 598.03m2·g-1 with concentrated mesopore size 9.2nm. The zeolites synthesised is composed ofuniform nanoparticles heaped with layer structure which formed connectivethree-dimensional mesoporous channel. In the aldolization reaction of benzaldehyde andglycol, the conversion of benzaldehyde was 80%, showed stronger catalytic performance oncatalysis reactions compared to ordinary ZSM-5 zeolite under the same condition.We synthesized micro-mesoporous zeolites Beta using PMMA with regulated grain sizeas template agents by hydrothermal synthesis method in this paper. The effect of synthesistemperature, different silicon source, the grain size and concentration of the PMMA templatesto the as-synthesized zeolites’ structure and morphology was discussed in the paper too. Theresults showed that: the micro-mesoporous zeolites Beta had multi-level pore structure andstrong thermal stability. Its BET surface area was 456.42 m2·g-1 with concentrated mesoporesize 5.33 nm. The zeolites synthesised is composed of uniform nanoparticles heaped withlayer structure which were consist of smaller hollow sphere. In the aldolization reaction ofbenzaldehyde and glycol, the conversion of benzaldehyde was 83%, showed strongercatalytic performance on catalysis reactions compared to ordinary Beta zeolite under thesame condition. What’s more, the structure of the micro-mesoporous zeolites Beta can changeto other spencial structure by changing synthesis temperature, the grain size andconcentration of the PMMA template, which can be applied to a lot of macromoleculecatalytic reaction.In this paper, we explored a new method of synthesising micro-mesoporous zeolitesZSM-5 and a mew template of synthesising micro-mesoporous zeolites Beta. The researchmentioned above not only has high values for exlporing new method and template, but alsocan found a good base to the further fundamental study on the control of zeolitesmorphology.