Synthesis and characterization of bifunctional transition-metal/silica-alumina catalysts for the chloromethane conversion to hydrocarbons

• Autor(a) principal: Rojas, Leopoldo Osvaldo Alcazar
• Data de Publicação: 2008
• Outros Autores: Nascimento, José Carlos, Ruiz, Juan Alberto Chavez, Benachour, Monhad, Sousa, João Fernandes de
• Tipo de documento: Artigo
• Idioma: eng
• Título da fonte: Repositório Institucional da UFRN
• Texto Completo: https://repositorio.ufrn.br/handle/123456789/40837
• topic: Fixed-bed reactor; Desorption energy; Chloromethane; Olefins; Silica alumina

In this work bifunctional (metal-acid) catalysts of Fe, Ni, Fe2O3 and NiO over amorphous silica alumina support were characterized (acidity) and evaluated for the conversion of chloromethane in a fixed bed reactor. Temperature program tests TPD (Temperature Programmed Desorption) and TPR (Temperature Programmed Reduction) were performed to characterize the quimissorption sites for the impregnated and unimpregnated support. New adsorption sites were created on the metal supported catalysts. The conversion yield of chloromethane was evaluated for the five materials. The highest conversion conversion (85%) was observed for the unmodified support (SiAl) after 6 of reaction at 860 K and a WHSV (Weight Hourly Space Velocity) of 4,5 h-1. The best selectivity toward desirable hydrocarbons (C3, C4) was found for the Fe-SiAl catalyst. C3 was also found in the products stream when Ni/SiAl and NiO/SiAl catalyts were tested. Ni catalysts were the most favorable to methane production. The catalytic tests showed coke formation in all materials. For the SiAl support the desorption energy of chloromethane, determined by TPD runs, was 101,9 KJ/mol. The metals presented lower desorption energies (75,2 KJ/mol for Ni and 133,4 KJ/mol for Fe) than the oxides (190,1 KJ/mol for Fe2O3 and 322,4 KJ/mol for NiO)