Alquila??o do tolueno com metanol sobre ze?litas modificadas com cations alcalinos e aipons

• Ano de defesa: 1997
• Autor(a) principal: Machado J?nior, H?lio Fernandes
• Orientador(a): Ferreira, Jos? Carlos Netto
• Banca de defesa: Ferreira, Jos? Carlos Netto, Cardoso, Dilson, Frety, Roger, Silva, Maria Isabel Pais da, Fraiz Junior, Silas Varella
• Tipo de documento: Tese
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal Rural do Rio de Janeiro
• Programa de Pós-Graduação: Programa de P?s-Gradua??o em Qu?mica
• Departamento: Instituto de Ci?ncias Exatas
• País: Brasil
• Palavras-chave em Português: ze?litas; Alquila??o; Cat?lise b?sica; AlPONs; nitreta??o
• Área do conhecimento CNPq: Qu?mica
• Link de acesso: https://tede.ufrrj.br/jspui/handle/jspui/4227

Styrene is not only one of the most important monomers for rubber production but it is also used in the production of polystyrene plastics. Polystyrene is one of the oldest synthetic resins and the third in volumetric production. It is largely used as packaging foam and in the production of plastic sheets. In the traditional process ethylbenzene is dehydrogenated to produce styrene. This ethylbenzene is produced through the alkylation of benzene with ethene over an AlCl 3 catalyst, H3PO4 or silica-alumina catalysts (Friedel-Crafts alkylation). Due to the high cost of this process some studies on the alkylation of toluene with methanol over basic catalysts have been made, in particular with zeolites through ionic exchange with alkaline cations. In this work the effects of the basic sites incorporated to zeolites Y and ZSM-5 over the catalytic activity were studied for the selective production of styrene and/or ethylbenzene through the alkylation oftoluene with methanol. The same study was conducted with amorphous aluminophosphates treated with ammonia at high temperatures. The zeolite Y exchanged with Cs presented the highest selectivity for the production of ethylbenzene and styrene in the reactions of basic catalysis. The exchanges made in the zeolites ZSM-5 were not effective for the particular reaction of basic catalysis as they produced preferentially xylenes and polialkylates, a typical result of an acid catalysis reaction. The aluminophosphates with a great nitrogen content, i.e., with a great number of basic sites, did not favored the production of ethylbenzene nor styrene. In this case methanol was preferentially decomposed. The analysis of the whole set of results allow us to conclude that the ideal catalyst for the alkylation of the toluene's side chain with methanol should have an intermediate basic strength together with a mild acidity in a regular crystalline structure.