doctoralThesis
Síntese e caracterização de zeólita beta hierarquizada e materiais híbridos micro-mesoporosos aplicados no craqueamento de PEAD
Fecha
2013-11-29Registro en:
CALDEIRA, Vinícius Patrício da Silva. Síntese e caracterização de zeólita beta hierarquizada e materiais híbridos micro-mesoporosos aplicados no craqueamento de PEAD. 2013. 145 f. Tese (Doutorado em Físico-Química; Química) - Universidade Federal do Rio Grande do Norte, Natal, 2013.
Autor
Caldeira, Vinícius Patrício da Silva
Resumen
A catalyst of great interest to the scientific community tries to unite the structure of
ordered pore diameter from mesoporous materials with the properties of stability and acid
activity to microporous zeolites. Thus a large number of materials was developed in the past
decades, which although being reported as zeolites intrinsically they fail to comply with some
relevant characteristics to zeolites, and recently were named zeolitic materials of high
accessibility. Among the various synthesis strategies employed, the present research
approaches the synthesis methods of crystallization of silanized protozeolitic units and the
method of protozeolitic units molded around surfactant micelles, in order for get materials
defined as hierarchical zeolites and micro-mesoporous hybrid materials, respectively. As goal
BEA/MCM-41 hybrid catalysts with bimodal pore structure formed by nuclei of zeolite Beta
and cationic surfactant cetyltrimethylammonium were developed. As also was successfully
synthesized the hierarchical Beta zeolite having a secondary porosity, in addition to the
typical and uniform zeolite micropores. Both catalysts were applied in reactions of catalytic
cracking of high density polyethylene (HDPE), to evaluate its properties in catalytic activity,
aiming at the recycling of waste plastics to obtain high value-added raw materials and fuels.
The BEA/MCM-41 hybrid materials with 0 days of pre-crystallization did not show enough
properties for use in catalytic cracking reactions, but they showed superior catalytic properties
compared to those ordered mesoporous materials of Al-MCM-41 type. The structure of Beta
zeolite with hierarchical porosity leads the accessibility of HDPE bulky molecules to active
centers, due to high external area. And provides higher conversion to hydrocarbons in the
gasoline range, especially olefins which have great interest in the petrochemical industry