The original crystalline structure of clay minerals can be altered in a controlled way, through acid or thermal treatments, resulting then in suitable products to be used as catalysts. This paper aims to characterize the red smectite clays of Boa-Vista, Paraíba (Brazil) in their natural form, and after chemical, thermal and acid treatments by X-ray fluorescence, differential thermal analysis, dynamic X-ray diffraction, classic X-ray diffraction analysis, scanning electron microscopy, nitrogen adsorption and model reaction. The results show that acid treatment partially altered the structure of the montimorillonite. An important increase in the surface area of the solid obtained was observed. The obtained reaction for the treated material showed that the clay was more acid than the natural one, yielding a better catalytic activity.
ResumoEste trabalho tem como objetivo caracterizar a argila de Toritama, estado de Pernambuco, na sua forma "in natura" após ativação térmica a 500 °C visando sua utilização na remoção de Cd 2+ . A argila "in natura" foi caracterizada por meio de espectrometria de raios X por energia dispersiva (EDX), difração de raios X e análise textural usando adsorção física de nitrogênio (BET). As argilas ativadas termicamente (100, 200, 300, 400 e 500 °C) foram caracterizadas por difração de raios X. A argila ativada termicamente a 500 °C foi caracterizada por EDX e BET. A remoção do Cd 2+ pela argila ativada termicamente foi realizada em sistema de banho finito. O tratamento térmico modificou levemente a área, como mostrou a análise de área de superfície específica, mas não modificou a distribuição de diâmetro de poros. Os dados experimentais para o sistema de banho finito se ajustaram aos modelos estudados, Langmuir e Freundlich; no entanto, o modelo de Freundlich foi mais satisfatório. O processo de remoção de cádmio em sistema de banho finito pela argila de Toritama ativada termicamente a 500 °C só atinge o equilíbrio depois de 120 min e apresenta um percentual de cerca de 86,8% de remoção de cádmio.Palavras-chave: tratamento térmico, caracterização, argilas, metais pesados, adsorção. (100, 200, 300, 400
Abstract
The purpose of this study is to characterize the clay of Toritama (Pernambuco, Brazil), in its form "in nature", and also after thermal activation at 500 °C, aiming its use in the removal of Cd
2+ . The clay "in nature" was characterized byg X-ray spectrometry by dispersive energy (EDX), X-ray diffraction (XRD), and surface area measurement by physical adsorption of nitrogen (BET). The thermally activated clay
Organophilic clays were prepared using a bentonite from the town of Boa Vista, state of Paraíba, Brazil, and a quaternary ammonium salt (Genamin CTAC-50). The materials obtained were characterized by X-ray diffraction and infrared spectroscopy. The results showed a good gasoline, toluene, diesel fuel and kerosene adsorbing capacity
Current specifications for gasoline impose strong restrictions on the content of aromatic compounds. Isomerization of normal paraffins to isoparaffins is considered an important petroleum reaction for the production of clean gasoline to improve its Research Octane Number (RON) and Motor Octane Number (MON). The isoparaffins are considered as an alternative to the use of oxygenated and aromatic compounds, whose maximum contents are subjected to strict regulations in order to protect the environment. In this work, catalysts supported on mordenite were obtained by competitive ion exchange using aqueous solutions of platinum complexes. Different concentrations of platinum were tested for the isomerization of n-hexane. All the catalysts obtained were shown to be selective to the formation of isomers with high-octane number, which are the products of greatest interest in the oil refining industry. The highest conversion and the best selectivity for 2,3-dmC 4 di-branched component, the isomer with the highest octane number, were found with the 1.10 wt% Pt/HMOR.
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