Evaluation of the acid properties of aluminossilicate MCM-22 material synthesized under static conditions

Abstract

The hydrothermal synthesis of MCM-22 zeolite was carried out using silica, sodium aluminate and hexamethyleneimine, under static conditions at 150°C for a period of 10 days, followed by washing with deionized water, drying overnight and calcination at 650°C. The obtained material was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM). The XRD analysis evidenced that MCM-22 presented a well defined MWW structure. The FT-IR spectrum confirmed the efficiency of the hexamethyleneimine as an organic template used to direct the structure of the MCM-22 zeolite under static conditions. The SEM image indicated that the particles are spherical in shape, with a diameter of ca. 10 µm. The acid properties of the MCM-22 zeolite, as determined by n-buthylamine adsorption, were investigated in the temperature ranges of 105 to 300°C and 300 to 525°C, relative to medium and strong acid sites, respectively.

Influence of the methodology on the formation of zeolite membranes MCM-22 for the oil/water emulsion separation

“…Table II shows permeate flow and rejection coefficient data of the present study and some data presented in the literature. The zeolite membranes produced in this study (ZMDC and ZMVPT) presented satisfactory results when compared with the results found in the literature [50][51][52][53][54][55][56][57][58][59]. The results found for the zeolite membranes MCM-22 independent of the method used, dip coating or vapor transport, were similar, evidencing that the production method had no influence on the results.…”

“…This work is part of a line of research developed at the Laboratory of Development of New Materials-LABNOV of the UFCG. This line of research covered a series of studies on the synthesis of zeolite membranes in the oil/water emulsion separation process [50][51][52][53][54][55][56][57][58][59][60][61][62][63][64][65]. This study is an integral part of this line of research and proposes the development of efficient membranes for the oil/water emulsion separation process.…”

Síntese do percursor (P)MCM-22 e modificações térmica, deslaminação e acidificação

“…A metodologia utilizada foi baseada no trabalho dos autores (Rodrigues et al, 2015). Foi preparada uma solução de hidróxido de sódio com 1,93 g dissolvidos em 415 g de água deionizada.…”

“…A intercalação da hexametilenoimina (HMI) entre as camadas da amostra precursora conduz ao surgimento do pico indexado (002) em 2θ = 6,56° -7,78°, comprovando a morfologia de camadas lamelares característica deste material Research, Society and Development, v. 10, n. 14, e599101422539, 2021 (CC BY 4.0) | ISSN 2525-3409 | DOI: http://dx.doi.org/10.33448/rsd-v10i14.22539 10 (Ravishankar, et al, 2005). A formação do precursor foi então comprovada por seu difratograma de raios X apresentado na Figura 2a, o qual está em concordância com os trabalhos relatados na literatura (Lawton et al, 1996;Calgaroto et al, 2011;Carriço, et al, 2013;Elyassi, et al, 2014;Rodrigues, et al, 2015) mostrando tratar-se do precursor da zeólita MCM-22.…”

“…A superfície de cada dupla camada é formada por semicavidades MWW, que durante a calcinação a temperaturas elevadas (~ 450 °C) se condensam originando a cavidade MWW completa e eliminando o direcionador de estrutura (Lawton et al, 1998;Narkhede & Gies, 2009). Nosso grupo de pesquisa tem desenvolvido e publicado alguns trabalhos sobre a preparação de vários tipos de zeólitas (Leite, 2007;Leite, Sousa & Rodrigues, 2009;Silva et al, 2010;Barbosa et al, 2010;Sousa et al, 2010;Barbosa, 2011;Silva, 2012;Santos et al, 2012;Rodrigues et al, 2015;Lima, 2015;Santos et al, 2015;Lima et al, 2015;Severo et al, 2016;Quintela, 2016;De Paula et al, 2019;Silva et al, 2020;Araújo Filho et al, 2021 ).…”