PETR 59 |
| In this study, powdered silicon dioxide, potassium dioxide and sodium dioxide were used as starting materials to prepare zeolites K-L. We examined the influence of reaction temperature, time and the content of the seeds on the formation of zeolites. A large scale synthesis was carried out in a 50-litre reactor under the optimized conditions. Treatment of the obtained zeolites KL with a series of ionic exchange and dealuminization led to the final solid products, which were characterized by the X-ray diffraction, TPD (Temperature-Programmed Desorption), TG, N2-BET, pyridine-adsorption IR, SEM, and chemical composition analysis. The zeolites L were prepared by heating a gel mixture of the starting materials in a high-pressure stainless steel autoclave at 150°C for 48 hours under the self-generated pressure. Zeolite L is a well-defined crystal: N2-BET surface area 407.65 m2/g, and particle size about 3 ƒÝm. It is stable at temperatures above 1000°C in the TG analysis. The decationization of zeolite L was carried out by exchanging its K+ ion with NH4+ ions from ammonium chloride, ammonium sulfate or ammonium nitrate. The ammonium-ion exchanged molecular sieves were then heated to drive off ammonia, resulting in the hydrogen form of Zeolites L. The effects of various ion-exchange conditions to the exchange degree and the framework of zeolites L including reaction temperature, time, solid/liquid ratio, and calcinations temperature were investigated in this paper. It has been found that the mass percent of the potassium oxide can be reduced to below 1.0% while the framework of the zeolites L retains intact. |
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Division of Petroleum Chemistry Poster Session
8:30 AM-10:30 AM, Monday, 11 September 2006 Moscone Center -- Hall D, Poster
Division of Petroleum Chemistry |