Metal nanoparticles as catalysts for oxidation reactions

• Autor(a) principal: Ying, Yu
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10400.13/1537
• topic: Gold nanoparticles; Carbon materials; Heterogeneous catalyst; Oxidation; Nanopartículas de ouro; Materiais de carbono; Catalisador heterogéneo; Oxidação; Nanochemistry and Nanomaterials; .; Faculdade de Ciências Exatas e da Engenharia; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia dos Materiais; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Química

Gold catalysts are currently a “hot topic” of research, as they show application in many reactions of industrial and environmental importance. The catalytic activity of gold nanoparticles supported on different carbon materials, as heterogeneous catalysts, was tested for the microwave-assisted solvent-free oxidation of 1-phenylethanol by tert-butyl hydroperoxide (TBHP). The catalytic performance was related to the support interaction, reaction time and temperature, quantity of catalyst, presence of additives, and other parameters. The possibility of recycling the catalysts was also investigated. Gold nanoparticles (1 wt. %) supported on a variety of carbon materials (activated carbon, graphite, silicon carbide, carbon xerogel, nanodiamonds, and microdiamonds), by two different methods (colloidal method and double impregnation), were used as catalysts for the oxidation of 1-phenylethanol. A maximum yield of acetophenone (99.9%) was obtained with Au nanoparticles supported on microdiamonds by colloidal method, while Au nanoparticles supported on silicon carbide by double impregnation method led to the minimum yield of 27.1%. Moreover, catalyst recyclability was tested up to six consecutive cycles at the optimized conditions for each catalyst, and it was observed that the catalytic activity of gold nanoparticles supported on microdiamonds, prepared by the colloidal method, maintains higher activity when compared with other catalysts after several reaction cycles. In addition, copper nanoparticles supported on carbon nanotubes were tested for degradation of dyes. However, the obtained results were not suitable to be presented and therefore are compiled in appendix.