Article

Synthesis of zeolitic materials from natural clinker: A new alternative for recycling coal combustion by-products

School of Applied Sciences, The University of Wolverhampton, Wulfruna Street, Wolverhampton WV1 1LY, UK
Fuel (Impact Factor: 3.52). 09/2008; 87(12):2482-2492. DOI: 10.1016/j.fuel.2008.03.014
Source: OAI

ABSTRACT

In this study, we report an innovative process of zeolite synthesis through transforming of natural raw clinker (NRC) via (1) conventional hydrothermal alkaline activation and (2) alkaline fusion prior to hydrothermal reaction. Both methods were evaluated at 100 °C as a function of the alkaline agent, although in the first method other variables such as concentration of the activation solution and reaction time were selected, whereas in the second method similar ratios of alkaline activator/NRC and H2O/alkali fused product during different reaction times were used. Experimental results indicate that the method, alkali activator, concentration and time have a strong effect on the type and degree of crystallinity of the synthesized zeolite. Low-silica sodium or potassium zeolitic materials were synthesized, which include Na-phillipsite, hydroxysodalite and hydroxycancrinite, K-chabazite, zeolite K-F, faujasite and zeolite Linde Type A. The use of a recycling process of NRC in zeolite synthesis could become an area of important interest and research, playing an active role in encouraging and promoting technological advances, research and technology transfer related to the use and disposal of mining wastes, remaining after the natural and spontaneous combustion of coal seams. NRC-based zeolites (NRCZs) synthesized under well-optimized experimental conditions could be used in applications for environmental waste treatment.

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    • "Its structure consists of a framework of 4-and 6-membered rings of SiO 4 and AlO 4 tetrahedra, and the Si:Al ratio equals 1:1, which is the lowest possible ratio for zeolite group minerals. There are many reports for the synthesis of hydroxysodalite from various raw materials, such as coal fly ash [6]-[13], paper sludge ash [14-[23], oil shale ash [24], [25], waste sandstone cake [26]-[29], natural kaolinite [30], metakaolin [31], expanded perlite [32], waste porcelain [33], natural clinker [34], thermally treated sediment [35] and so on. Hydroxysodalite has recently been proposed as an adsorbent of hydrogen chloride from high-temperature incinerator exhaust gases. "

    Preview · Article · Aug 2016
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    • "The synthesis of zeolites developed using two types of alkaline fusions prior to two aging methods and the hydrothermal treatment. Optimal conditions for the synthesis of zeolites from coal by-products with a maximum value of cation exchange capacity are a coal by-product/alkaline activator ratio of 1:1.2 [17] [18]. Therefore, alkali hydroxide powder was mixed with natural clinker using two methods, one with dry alkali and the other with alkali dissolved in water forming a saturated solution. "
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    ABSTRACT: A sample of Colombian natural clinker was evaluated as a raw material in a laboratory-scale synthesis of zeolitic materials using two methods of alkaline fusion, followed by two aging methods, and finally hydrothermal treatment during three different periods of time. Fusion was carried out with solid and aqueous NaOH and followed by static or ultrasonic aging. The process ended with a hydrothermal reaction. Natural clinker was converted into several zeolitic materials. The characteristics of the resulting zeolitic materials and the effects of experimental variations are discussed.
    Preview · Article · Oct 2015 · Dyna (Medellin, Colombia)
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    • "Se han desarrollados otros métodos de síntesis para disminuir los tiempos del procesos hidrotermal, la técnica de sembrado fue usada por Mignoni et al [8] para la obtención de zeolita tipo mordenita de altas relaciones Si/Al ~20 y ZSM-5 por medio de la introducción de fuentes de Si y Al adicionales al metacaolín. La técnica de ultrasonido fue usada por Park y Kim [9] para reducir los tiempos de síntesis y la temperatura de reacción obteniendo productos como zeolita A con mayor grado de cristalinidad al obtenido por medio del método de síntesis hidrotermal; la síntesis por microondas, en el cual se aprovecha la energía del microondas para la etapa inicial de calentamiento durante la síntesis y a diferencia del método hidrotermal en la cual se elimina el gradiente de temperatura en la mezcla [10] y el método denominado hidrotermal con previa fusión, en el cual el caolín es calcinado en soluciones alcalinas en presencia de NaOH o de KOH alrededor de los 600ºC y posteriormente se sigue con la síntesis hidrotermal, este método ha sido aplicado igualmente a otros materiales de partida [11]. "
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    ABSTRACT: The utilization of Exhausted Fluid Catalytic Cracking Catalysts, (FCC), as raw materials for the low-silica zeolite synthesis was analyzed. The FCC, is mainly composed aluminosilicates orders of up to 90%, and has a chemical composition similar to that metakaolin. Therefore, the same synthesis parameters (Na2O/SiO2 and H2O/Al2O3 molar ratios, temperature and time), obtained in previous studies for obtaining zeolites from the thermal activation of a natural kaolin are used in the process. The zeolites obtained were characterized by scanning electron microscopy and X-ray diffraction. The Cation Exchange Capacity was also determined. The results indicate that is possible to recover the FCC for obtaining zeolites type A, with Cation Exchange Capacity 341,47 mequiv/100g. The results obtained in this study provide an important perspective for the reusing of FCC in the production of zeolitic materials considering that in Colombia the zeolites are imported and are of high demand in the industrial sector. It should be noted that the exchange capacity of the zeolites obtained from kaolin by the same process parameters is 442 mequiv/100g, and zeolites imported for use in the domestic industry is 408 mequiv/100g.
    Full-text · Article · Apr 2015 · Revista Latinoamericana de Metalurgia y Materiales
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