The objective of this work was the development of structured zeolite catalysts by growing of ZSM-5 and Y zeolites layers on the pre-treated FeCrAlloy wires, which could now offer technical advantage in catalytic application. The advantages of implementation of zeolitic coatings in industrial applications are that they have; lower pressure drop, high heat and mass transfer rates compared to standard pelleted or extruded catalysts. The key focus of this research was the generation of thin films of zeolite ZSM–5 and Y zeolite catalysts on the surface of a FeCrAlloy metal substrate. Using in-situ hydrothermal synthesis, the influence of the synthesis parameters such as substrate oxidation and crystallisation time on the zeolite crystallisation process in both the bulk phase (powder) and on the structured zeolite was studied and optimised. Then powder and structured Na-ZSM-5 and Na-Y were treated by calcination and ion exchange in post-synthesis treatment. Further post-synthesis modification was required in the zeolite Y case to improve the catalytic properties. The post synthetic modification of zeolite Y was carried out using acidified ammonium nitrate which was optimised to produce dealuminated zeolite Y with good crystallinity and a Si/Al = 8. Characterisation was performed after each stage of this work to optimise catalyst development using XRD, SEM, EDAX, BET, MAS-NMR, and TGA. Once the optimised zeolite Y and ZSM-5 structured catalysts prepared, cracking of n-heptane was carried out to assess the in catalytic performance compared with Y and ZSM-5 pellets in a fixed-bed reactor under the same operation conditions. The cracking of n–heptane over the pellets and structured catalysts for both ZSM–5 and Y zeolite showed very similar product selectivities for similar amounts of catalyst with apparent activation energy of around 60 kJ mol-1. This research demonstrates that structured catalysts can be manufactured with excellent zeolite adherence and when suitably activated/modified give comparable cracking results to the pelleted powder forms. These structured catalysts will improve temperature distribution in highly exothermic and endothermic catalysed processes.

Comparative studies over micro-/mesoporous Cu-containing zeolites ZSM-5 prepared by top-down treatment involving NaOH, TPAOH or mixture of NaOH/TPAOH (tetrapropylammonium hydroxide) were conducted. The results of the catalytic data revealed the highest activity of the Cu-ZSM-5 catalyst both in the absence and presence of water vapor. The physico-chemical characterization (diffuse reflectance UV-Vis (DR UV-Vis), Fourier transform infrared (FT-IR) spectroscopy, electron paramagnetic resonance (EPR) spectroscopy, temperature-programmed desorption of NOx (TPD-NOx), and microkinetic modeling) results indicated that the microporous structure of ZSM-5 effectively stabilized isolated Cu ion monomers. Besides the attempts targeted to the modification of the textural properties of the parent ZSM-5, in the next approach, we studied the effect of the co-presence of sodium and copper cations in the microporous H-ZSM-5. The presence of co-cation promoted the evolution of [Cu–O–Cu]2+ dimers that bind NOx strongly with the desorption energy barrier of least 80 kJ mol−1. Water presence in the gas phase significantly decreases the rate of ammonia oxidation, while the reaction rates and activation energies of NH3-SCR remain unaffected.

Made available in DSpace on 2014-12-17T15:41:53Z (GMT). No. of bitstreams: 1 ViniciusPSC_DISSERT.pdf: 2657914 bytes, checksum: beb97c8aaf506ef6b97930de865d3dd2 (MD5) Previous issue date: 2011-02-25 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior / The catalytic processes play a vital role in the worldwide economy, a business that handles about US$ 13 billion per year because the value of products depends on the catalytic processes, including petroleum products, chemicals, pharmaceuticals, synthetic rubbers and plastics, among others. The zeolite ZSM-5 is used as catalyst for various reactions in the area petrochemical, petroleum refining and fine chemicals, especially the reactions of cracking, isomerization, alkylation, aromatization of olefins, among others. Many researchers have studied the hydrothermal synthesis of zeolite ZSM-5 free template and they obtained satisfactory results, so this study aims to evaluate the hydrothermal synthesis and the physicochemical properties of ZSM-5 with the presence and absence of template compared with commercial ZSM-5. The methods for hydrothermal synthesis of zeolite ZSM-5 are of scientific knowledge, providing the chemical composition required for the formation of zeolitic structure in the presence and absence of template. Samples of both zeolites ZSM-5 in protonic form were obtained by heat treatment and ion exchange, according to procedures reported in the literature. The sample of commercial ZSM-5 was acquired by the company Sentex Industrial Ltda. All samples were characterized by XRD, SEM, FTIR, TG / DTG / DSC, N2 adsorption and desorption and study of acidity by thermo-desorption of probe molecule (n-butylamine), in order to understand their physicochemical properties. The efficiency of the methods applied in this work and reported in the literature has been proved by well-defined structure of ZSM-5. According as the evaluation of physicochemical properties, zeolite ZSM-5 free template becomes promising for application in the refining processes or use as catalytic support, since its synthesis reduces environmental impacts and production costs / Os processos catal?ticos desempenham um papel vital na economia mundial, um neg?cio que movimenta aproximadamente US$13 bilh?es por ano, pois o valor dos produtos depende dos processos catal?ticos, incluindo os produtos petrol?feros, qu?micos, farmac?uticos, borrachas sint?ticas e pl?sticos, entre outros. A ze?lita ZSM-5 ? utilizada como catalisador em rea??es nas ?reas petroqu?mica, petrol?fera e qu?mica fina, destacando-se as rea??es de craqueamento, isomeriza??o, alquila??o, aromatiza??o de olefinas, entre outras. Muitos pesquisadores t?m estudado a s?ntese hidrot?rmica da ze?lita ZSM-5 ausente de direcionador org?nico estrutural e obtiveram resultados satisfat?rios, assim, este estudo visa avaliar a s?ntese hidrot?rmica e as propriedades f?sico-qu?micas da ZSM-5 com a presen?a e aus?ncia de direcionador org?nico estrutural, em compara??o com ZSM-5 comercial. Os m?todos para a s?ntese hidrot?rmica da ze?lita ZSM-5 s?o de conhecimento cient?fico, fornecendo a composi??o qu?mica necess?ria para a forma??o da estrutura zeol?tica em presen?a e aus?ncia de direcionador org?nico estrutural. As amostras de ambas as ze?litas ZSM-5 na forma prot?nica foram obtidas atrav?s de tratamentos t?rmicos e troca i?nica, de acordo com procedimentos relatados na literatura. A amostra de ZSM-5 comercial foi concedida pela empresa Sentex Industrial Ltda. Todas as amostras foram caracterizadas por DRX, MEV, FTIR, TG/DTG/DSC, Adsor??o e dessor??o de N2 e estudo da acidez por termodessor??o de mol?cula sonda (n-butilamina), a fim de compreender suas propriedades f?sico-qu?micas. A efici?ncia dos m?todos aplicados no presente trabalho e relatados na literatura foi comprovada pela estrutura bem definida da ze?lita ZSM-5. Conforme a avalia??o das propriedades f?sico-qu?micas, a ze?lita ZSM-5 ausente de direcionador org?nico torna-se promissora para aplica??o em processos de refino ou utiliza??o como suporte catal?tico, visto que, sua s?ntese reduz os impactos ambientais e custos de produ??o