Dissertation > Excellent graduate degree dissertation topics show

Hierarchical ZSM-5 Zeolite: Synthesis and Catalytic Application

Author: YuSuXia
Tutor: WangJinQu；YangJianHua
School: Dalian University of Technology
Course: Chemical processes
Keywords: Methane dehydroaromatization nanocrystal zeolite hierarchical zeolite nanocrystal aggregation ZSM-5 zeolite
CLC: O643.36
Type: Master's thesis
Year: 2009
Downloads: 611
Quote: 2
Read: Download Dissertation

Abstract


The direct conversion of methane into aromatics such as benzene and toluene under non-oxidative conditions opens a new approach to the catalytic transformation of methane into high value-added chemicals and the comprehensive utilization of nature gas.Mo/HZSM -5 catalyst is regardes as one of the best catalsyst for methane dehydroaromatization.The acidity and the pore structure of HZSM-5 plays an important role in the methane activitation and benzene formation.However,the microporous chracteristics restricted the diffusion of molecules to internal catalytic sites,particularly when the diffusion in the micropores is significantly slower than the reaction.Nano and hierarchical structure zeolite posess both the microporous and mesoporous pores is explored to overcome this problem.The study on zeolite nano and hierarchical structure crystals were of significance for the methane dehydroaromatization.In this dissertation,the ZSM-5 nanocrystals were synthesized with the hydrothermal method,and the effect of SiO2/Al2O3 and H2O/SiO2 and temperature and the addition of NaCl on the crystal size of the ZSM-5 were studied.Hierarchical ZSM-5 microspheres were synthesized through controlling the synthesis conditions without any secondary templat and their catalytic performance for methane dehydroaromatization was investigated.Getting some enlightenment from this,the hierarchical ZSM-5 nanospheres were synthesized without any secondary template.Finally hierarchical ZSM-5 zeolites were synthesized by using carbon nanotubes as template,which was assembly by ZSM-5 rod-shaped nanocrystals.The hierarchical ZSM-5 zeolites were applied in methane dehydroaromatization and the good results were obtained.The main results and conclusion obtained in this dissertation were as follows:（1） The effect of SiO2/Al2O3 and H2O/SiO2 and temperature and the addition of NaCl on the crystal size of the ZSM-5 were studied.The crystal size of zeolite was minished with the decrease of the SiO2/Al2O3 and H2O/SiO2 and temperature,and ZSM-5 zeolite with size of 100-200 nm were synthesized,and the size of ZSM-5 zeolite was decreased to 65 nm when NaCl was added.（2） Hierarchical ZSM-5 microspheres with the size of 10-15μm were synthesized without any secondary template,and the microspheres were the assembled by many rod-shaped crystals layer-by-layer.When used in methane dehydroaromatization the microsphere Mo/HZSM-5 catalyst exhibited good performance,the initial CH4 conversion and benzene yield was 18.5%and 9.5%,which is higher than the conventional catalyst（CH4 conversion is 12%）,when the reaction duration came to 24 h,the CH4 conversion and benzene yield was 10%and 5%.（3） The hierarchical ZSM-5 nanospheres with the size of 200-300 nm were synthesized without any secondary template,which were assembled by many sheet-nanocrystals.When used in methane dehydroaromatization the nanosphere Mo/HZSM-5 catalyst exhibited good performance,the initial CH4 conversion and benzene yield was 16%and 8.5%,when the reaction duration came to 24 h,the CH4 conversion and benzene yield was 9%and 4.5%.（4） The hierarchical ZSM-5 nanosperes-like with the size of 300-400 nm were synthesized use carbon nanotube as secondary template,which was the assembly of many rod-shaped nanocrystals of 30-40nm.When used in methane dehydroaromatization the nanosphere Mo/HZSM-5 catalyst exhibited good performance,the initial CH4 conversion and benzene yield was 19.5%and 10.5%,when the reaction duration came to 24 h,the CH4 conversion and benzene yield was 10%and 5%.Compared to the conventional catalysts,the percentage increases of CH4 conversion is 62.5%.

Related Dissertations

  1. Mixing two shape-selective cracking of cumene,TQ244.2
  2. Synthesis of Fe-ZSM-5 and Application in the Hydroxylation of Phenol,TQ203
  3. The Study of Ethylene Protonation on HZSM-5 Zeolite with Neighboring Br(?)nsted Acid Sites,O621.25
  4. Study of Theoretical Calculation of Ethylene Dimerization Reaction on Ga(Al)/HZSM-5 Zeolite,O621.25
  5. Study on Synthesis and Catalytic Performance of Zeolite ZSM-22,O643.36
  6. Moidification and Application of New Catalytic Material for Hydrogenation and Modification of Gasoline,TE624.93
  7. Study on the Catalyst for Producing More Light Olefines by Catalytic Cracking Process,TE624.41
  8. Study on the Acidities of the Modified HZSM-5 Zeolites,O643.36
  9. The Reaction Mechanisms of Ethylene Aromatization in H-ZSM-5 Zeolite: from C4 to C6 Intermediates,O643.12
  10. Synthesis Hierarchical ZSM-5 Zeolite and Membrane Reactor in Methane Dehydroaromatization,O643.36
  11. C4 LPG Low-temperature Aromatization without Using H2 as Carrier Gas,O643.32
  12. Study on the Low-temperature Aromatization of C4 Liquified Petroleum Gas over Nano-sized ZSM-5 Zeolite,O643.32
  13. Catalytic Performance of Nano-ZSM-5 Zeolite in the Reaction of Aromatization and Cyclamination,O643.36
  14. Low-temperature Aromatization of C4 Liquified Petroleum Gas over Nano-zeolites,O643.32
  15. Aromatization of Butenes in C4 LPG Over Nano-sized ZSM-5 Zeolite,O643.32
  16. Preparation, Characterization, Application of Nitrogen-Incorporated ZSM-5 Zeolites and Its Density Functional Theory Study,O643.36
  17. Quantum Chemistry Study on the Reactions of Light Hydrocarbons Conversion over Cation-Exchanged Zeolites,O643.32
  18. The Study of N2O Catalytic Decomposition and One-Step Oxidation Benzene to Phenol over Zeolites,O643.32
  19. Studies on the Crystallization and Modification of Zeolites in Various Gel Systems, and Catalysis of Ethanol Dehydration,TQ424.25
  20. Organotemplate-free Synthesis of ZSM-34 Zeolite and Its Analogue Containing Framework Heteroatoms in the Presence of Zeolite L Seeds Solution,O643.36

CLC: > Mathematical sciences and chemical > Chemistry > Physical Chemistry ( theoretical chemistry ),chemical physics > Chemical kinetics,catalysis > Catalytic > Catalyst
© 2012 www.DissertationTopic.Net  Mobile