Estudo te?rico da rea??o entre wustita e ?gua durante o processo de reforma em loop qu?mico

• Ano de defesa: 2019
• Autor(a) principal: Cordeiro, Giuliano de Mesquita
• Orientador(a): Silva, Clarissa Oliveira da
• Banca de defesa: Silva J?nior, Ant?nio Marques da, Rodrigues, Victor de Oliveira
• Tipo de documento: Dissertação
• 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 Qu?mica
• País: Brasil
• Palavras-chave em Português: Produ??o de hidrog?nio molecular; Processo de reforma em loop qu?mico; ?xido de ferro; Teoria do funcional de densidade
• Palavras-chave em Inglês: Molecular hydrogen production; Chemical looping reforming process; Iron Oxide; Density functional theory
• Área do conhecimento CNPq: Qu?mica
• Link de acesso: https://tede.ufrrj.br/jspui/handle/jspui/5053

Reliable energy supply is a key issue for global economic growth and development. Currently, most of the global energy is produced from fossil fuels, constituting a inadequate environmental choice and a questionable bet in a mid and long term future. In this context, the adoption of hydrogen as a new energy matrix emerges as a promising alternative to diminish greenhouse emissions and accordingly the climate change. In this dissertation, it is proposed the theoretical study of an iron-based catalyst that is able to perform efficiently the reactions of chemical looping reforming process. Because this process, when thus driven, eliminates the need for molecular hydrogen purification (produced pure in the first stage of the process) and provides carbon beneficiation, generating CO, which may be used in various synthetic reactions. The quantum-mechanical calculations were performed using the density functional theory. In the description of the chemical system under study, it was decided to employ the chemical cluster approach. The cluster model is justified by the small size that the catalyst particles must have (nanoparticles), so that they are efficient in the chemical loop process. As for the investigation of the reaction between the metal oxide and the water, it was verified that it takes place in two stages. Initially, the dissociative adsorption of the water in the metallic cluster occurs. Subsequently, the combination of the hydrogen atoms is performed to form the H2 molecule. The modeling of the electronic structures of the clusters presented in this study were performed both by the spin restricted Kohn-Sham orbitals description (for spin multiplicity equals 1) and by the spin unrestricted Kohn-Sham orbitals description. Based on energy and geometric evaluations, it was possible to infer that the unrestricted treatment is more adequate for the description of the reaction under study.