Formação de mesoporos em material zeolítico MCM-22 para o craqueamento catalítico do polietileno de alta densidade

• Ano de defesa: 2024
• Autor(a) principal: Lima, Rafael Barbalho de
• Orientador(a): Pergher, Sibele Berenice Castella
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal do Rio Grande do Norte
• Programa de Pós-Graduação: PROGRAMA DE PÓS-GRADUAÇÃO EM QUÍMICA
• País: BR
• Palavras-chave em Português: Química; Zeólita; MWW; Dessilicação; Hierarquização; Degradação
• Área do conhecimento CNPq: CIENCIAS EXATAS E DA TERRA::QUIMICA
• Link de acesso: https://repositorio.ufrn.br/handle/123456789/65848

Plastics are becoming more and more indispensable in everyday life, so they have interesting properties. However, the extensive use of these materials becomes a serious problem due to the inappropriate disposal of plastic waste. Catalytic cracking is presented as an appropriate method for chemical recycling of plastic waste. The zeolites are made from this process because they present unique characteristics that lead to obtaining desired products, better yields and providing lower temperatures. However, the presence of a uniquely microporous structure (pores até 2 nm) restricts its use in reactions that involve bulky molecules. A solution has been used to obtain hierarchical zeolites that present a combination of microporosity, with an additional level of porosity that can be in the range of mesopores (pores between 2 nm to 50 nm) or macropores (above 50 nm), allowing a greater accessibility. The alkaline treatment by means of the desilicação process promotes the formation of a secondary porosity by means of the removal of silicon atoms from the zeolitic structure. Without alkaline treatment, various factors of the zeolitic structure can influence the formation of secondary porosity, such as Si/Al ratio, morphology, structure, poredirecting agents, among others. This work was carried out by alkaline treatment in MCM-22 zeolite with Si/A ratio equal to 15 and 50, of two-dimensional and threedimensional structure, obtained in a rotational and static way, and with different types and quantities of pore-directing agents for degradation thermocatalytic highdensity polyethylene (HDPE). All synthesized materials present crystalline phases referring to the MWW zeolitic structure. The rotational form presents the morphology of agglomerates of thin, rounded platelets, while the static form presents more homogeneous and thick rounded platelets. The type of structure, type of pore directing agent and quantity, also because Yes/Al influences the alkaline treatment. Embora alkaline treatment has not been provided with the formation of secondary porosity, as our two-dimensional samples with 0.3g of Cetyltrimethylammonium Brometh present superior textural properties. All catalysts show lower degradation than thermal degradation of HDPE, with emphasis on catalysts that demonstrate larger external areas.