Luiz Di Souza

Catalytic cracking of sunflower oil under Zr catalysts using thermogravimetry

Catalytic cracking of vegetable oils is an alternative method for the production of biofuels. The use of catalysts such as MCM-41 with zirconium results in the presence of acid sites that favor the cracking reactions, where their catalytic activity can be evaluated by thermogravimetric analysis. The present work aimed to prepare and determine the physicochemical properties of a catalyst based on MCM-41 incorporated with different percentages of zirconium. The materials were characterized by X-ray diffraction, adsorption and desorption of N2, energy-dispersive X-ray, scanning electron microscopy, thermogravimetry (TG) and differential thermogravimetry (DTG). In addition, their catalytic behavior has been evaluated in the catalytic cracking of sunflower oil, through the TG/DTG/DSC thermal analysis techniques. The amount of the zirconium oxide incorporated into MCM-41 support has not destroyed the typical structure of MCM-41, and the insertion promoted a change to the pore diameter and pore volume, indicating the presence of oxide inside the pores and on the external area. All catalysts developed activity in sunflower oil cracking, even at low percentage of ZrO2, especially the Zr2-MCM-41 sample, which obtained more efficiency. Thus, all catalysts are promising for use in cracking, and thermogravimetric analysis has been proved effective for monitoring the catalytic activity.Graphical Abstract

Polyethylene catalytic cracking by thermogravimetric analysis

Polymer degradation by the catalytic cracking process has been investigated as an important way of hydrocarbon recovery with high added value. In addition, the effects of the catalyst properties and their behavior during the catalytic degradation of polyolefins have been studied using thermogravimetric analysis. In this context, the present work compares the interactions between the polymeric molecules and the contact surface of zeolitic catalysts (hierarchical and standard Beta zeolites, Y zeolite, ZSM-5, ZSM-12 and MCM-22) with different properties, in the catalytic cracking reactions of low-density polyethylene. It was also possible to evaluate distinct reaction mechanisms in function of the thermal homogenization procedure employed by thermogravimetric analysis. Among the zeolites with large pore diameters, the hierarchical Beta showed superior external area due to the use of a bulky silanized agent (phenylaminopropyl-trimethoxysilane) in the synthesis. In cracking reactions, the polymeric macromolecules mainly react in the external surface of the catalysts due to the several diffusional limitations imposed. Thus, the zeolitic catalysts exhibited behaviors respective to a combination of accessibility to the active centers and selectivity in function of the acid strength of the centers. So, based on this process, zeolites with larger external area values (hierarchical Beta, standard Beta, ZSM-5 and MCM-22) promoted the lower values of degradation temperature with high efficiency of conversion.Graphical Abstract

Síntese e Caracterização do Material Mesoporoso SBA-15 Obtido com Diferentes Condições de Síntese

Os materiais mesoporosos tem recebido muita atencao devido as suas caracteristicas promissoras na area de catalise, adsorcao e troca ionica. Dentre esses materiais se destaca o SBA -15 que possui uma estrutura hexagonal e unidirecional, grande estabilidade termica e hidrotermica e alto diâmetro medio de poros. A sintese desse material ocorre em meio acido, utilizando o P123 como direcionador orgânico e o TEOS como fonte de silica. Apesar de utilizar somente um direcionador orgânico, outros materiais a base de silica, como o KIT-6, utilizam um alcool como codirecionador de estrutura, reduzindo o tempo de envelhecimento em ate 24 horas em relacao ao SBA-15. O presente trabalho tem como objetivo sintetizar o SBA-15 utilizando o Butanol no processo de sintese, a fim de se obter um material em um menor tempo e caracteriza-lo com o intuito de avaliar a utilizacao do Butanol na sintese atraves dos materiais obtidos . As amostras foram sintetizadas conforme Zhao et al. (1998a) e com modificacoes utilizando o Butanol e caracterizados por DRX, TG/DTG, adsorcao/dessorcao de nitrogenio e MEV. O material sintetizado com o butanol apresentou propriedades texturais , estruturais e morfologicas semelhantes a amostra padrao, tipicas de materiais do tipo SBA-15, mesmo com a reducao de 24 horas de sua sintese. Os materiais sintetizados com o uso do alcool, apresentaram paredes mais espessas o que confere a esse material uma maior resistencia. Foi possivel reduzir o tempo de sintese do SBA-15 em 24 horas, obtendo-se materiais de alta qualidade, utilizando o Butanol durante a sua sintese.

Thermal and catalytic pyrolysis of vacuum gas oil using HZSM-5: TG and PY-CG/MS study

ABSTRACT The zeolite HZSM-5, was synthesized in the absence of an organic template. The characterization of zeolite HZSM-5 was performed by X-ray diffraction, N2 adsorption/desorption isotherms and scanning electron microscopy. For catalytic tests, applying the free kinetic model, it was observed that the activation energy for the pyrolysis of pure VGO was of 82 kJ mol−1 and for VGO/HZSM-5, the value decreased to approximately 60 kJ mol−1, demonstrating the effectiveness of the acid sites effect of zeolite ZSM-5 for the VGO pyrolysis resulting in production of gas, gasoline and diesel.

EXTRAÇÃO, HIDRO-ESTERIFICAÇÃO E METILAÇÃO DOS LIPIDIOS DA MACROALGA GRACILARIA CAUDATA, APLICANDO CATALISE HETEROGENEA NA PREPARAÇÃO DO BIODIESEL

O biodiesel se enquadra perfeitamente nas exigencias ambientais requeridas por ser um biocombustivel renovavel, biodegradavel e nao-toxico apresentando-se como uma possivel solucao para amenizar os problemas atuais provocado pela dependencia do petroleo pela sociedade, reduzindo alguns efeitos causadores do aquecimento global. O presente trabalho relata a extracao dos lipidios da macroalga Gracilaria caudata e a utilizacao dos mesmos na preparacao do biodiesel. A metodologia utilizada para extracao dos lipidios foi extracao a quente usando hexano como solvente e tambem o metodo de extracao a frio, usando a mistura de solventes, cloroformio/metanol numa proporcao de 2:1. O metodo de conversao foi hidro-esterificacao usando iodo sublimado na presenca de alcool, etilico ou metilico. Com essa metodologia pode-se obter resultados interessantes para a aplicacao do biodiesel feito a partir da materia prima.