Título:	Estudo da adsorção de álcoois e gás de síntese em óxido de magnésio, óxido de zinco e zeólita H-ZSM-5
Autor(es):	Costa, Rogério José da
Orientador(es):	Martins, João Batista Lopes
Coorientador(es):	Castro, Elton Anderson Santos de
Assunto:	Óxidos Zeólitas Química computacional Catálise heterogênea
Data de publicação:	18-Jun-2019
Data de defesa:	10-Dez-2018
Referência:	COSTA, Rogério José da. Estudo da adsorção de álcoois e gás de síntese em óxido de magnésio, óxido de zinco e zeólita H-ZSM-5. 2018. 139 f., il. Tese (Doutorado em Química)—Universidade de Brasília, Brasília, 2018.
Abstract:	Several molecules, present in the atmosphere and in industrial inputs and products, are of interest to the environmental and energetic impacts. Among the gases, such as hydrogen, carbon monoxide, carbon dioxide, water and methane, they are involved in the synthesis gas as well as in the water gas shift process, or even in the production of hydrogen, an important part of energy matrix. On the other hand, alcohols can be an important gasoline production industry, in addition to other important ones such as isomerization and dehydration process. These processes are catalyzed on zeolites, while the former are catalyzed on oxide surfaces. The theoretical study of the systems can be done through periodic methods and through clusters. The use of cluster is a technique widely used for the treatment of systems such as zeolites and oxides. However, it must be taken into account the periodic environment of the system studied. The ways to solve a surface by using clusters is carried out through the ONIOM hybrid method. This method has the main goal of working different levels of accuracy in the same system, reducing the computational impact, bringing important knowledge of the studied system. It is important to define the boundary conditions for this level, the partitioning, in addition to the theoretical level to use for each layer. Thus, this work brings an evaluation of different adsorption systems of small molecules, i.e., H2, CO, CO2, CH4 and H2O, as well as molecules with higher number of atoms, such as methanol, ethanol, propanol and butanol, as adsorbates. DFT methods, with B3LYP, M06-2X, wB97X-D functionals, were selected for the higher layer for the model system. The semi-empirical PM6 was also used for the high and low layers, and UFF for the low layer. The adsorption energy and adsorbate geometry were evaluated. For both the oxides and the zeolites, the relaxation of the surface of interest was achieved, always using the same procedure, either by optimizing a surface by stages, expanding a region of interest to bring a better representation of the environment where the adsorbate was studied . The PM6 method is used for the complete system, and the results are overestimated for the adsorption energy, however the use of the ONIOM method has enhanced the theoretical accuracy. In the case of zeolite, it was possible to access a greater number of systems and methods used, due to the behavior of the system and to the covalent character in the adsorbent. In total, the studies have a consolidated protocol for the study of adsorption in solids and zeolites. Allowing in the future, treat the mechanisms involved.
Unidade Acadêmica:	Instituto de Química (IQ)
Informações adicionais:	Tese (doutorado)—Universidade de Brasília, Instituto de Química, Programa de Pós-Graduação em Química, 2018.
Programa de pós-graduação:	Programa de Pós-Graduação em Química
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