https://repositorio.ufba.br/handle/ri/7282
Tipo: | Artigo de Periódico |
Título: | Liquid-Phase Selective Hydrogenation of Hexa-1,5-diene and Hexa-1,3-diene on Palladium Catalysts. Effect of Tin and Silver Addition |
Título(s) alternativo(s): | Journal of Catalysis |
Autor(es): | Sales, Emerson Andrade Mendes, Mario de Jesus Bozon Verduraz, François |
Autor(es): | Sales, Emerson Andrade Mendes, Mario de Jesus Bozon Verduraz, François |
Abstract: | The liquid-phase hydrogenation of hexa-1,5-diene and hexa-1,3-diene on alumina-supported palladium catalysts is investigated with special attention paid to the effects of tin or silver addition. All catalysts show a global selectivity near 100%; these high values persist at total conversion when the reactant is hexa-1,3-diene but decrease to about 70% in the case of hexa-1,5-diene. In the hexa-1,5-diene hydrogenation, monometallic palladium catalysts give mainly 1-hexene at conversions lower than 80% and E-hex-2-ene at higher conversions. The fractional selectivity to 1-hexene is significantly improved by tin or silver addition; however, significant yields are observed only on Pd–Sn catalysts with a low Sn/Pd atomic ratio (≈0.1) and when the intermetallic compound Pd3Sn is present. On the other hand, in the hexa-1,3-diene hydrogenation, hex-1-ene is preferentially formed on monometallic catalysts with low dispersion; on bimetallic Pd–Sn or Pd–Ag catalysts, the selectivity to E-hex-3-ene is enhanced and this isomer is even predominant up to 100% conversion on the Pd–Sn catalysts containing the Pd3Sn intermetallic compound. These results are explained by the geometric effect of dilution of Pd atoms, which delays the palladium double-bond isomerization ability. The proposed mechanism suggests that strongly adsorbed alkadienes react with dissolved hydrogen, following a zero-order kinetics. |
Palavras-chave: | Pd catalysts Pd–Sn catalysts Pd–Ag catalysts Selective hydrogenation Hexa-1,5-diene Hexa-1,3-diene |
Editora / Evento / Instituição: | Elsevier |
URI: | http://www.repositorio.ufba.br/ri/handle/ri/7282 |
Data do documento: | Out-2000 |
Aparece nas coleções: | Artigo Publicado em Periódico (Química) |
Arquivo | Descrição | Tamanho | Formato | |
---|---|---|---|---|
Sales.pdf Restricted Access | 133,77 kB | Adobe PDF | Visualizar/Abrir Solicitar uma cópia |
Os itens no repositório estão protegidos por copyright, com todos os direitos reservados, salvo quando é indicado o contrário.