The effect of metallic salt additives on direct sulfation of calcium carbonate and on decomposition of sulfated samples

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• 作者：Fuertes ; A.B. ; Fernandez ; M.J.
• 关键词：Additives ; Calcium carbonate ; Metallic salts ; Sulfation ; TGA
• 刊名：Thermochimica Acta
• 出版年：1996
• 出版时间：April 25, 1996
• 年：1996
• 卷：276
• 期：Complete
• 页码：257-269
• 全文大小：640 K

文摘

The effect of different types of metallic salt additives (Nab>2b>COb>3b>, Lib>2b>COb>3b>, Kb>2b>COb>3b>, Nab>2b>SOb>4b>, NaF, NaCl, ZnSOb>4b>, Ca(NOb>3b>)b>2b>, Csb>2b>COb>3b> and Alb>2b>(SOb>4b>)b>3b>) on direct sulfation of calcium carbonate is investigated. The experiments were carried out in a thermogravimetric analyzer under isothermal conditions at temperatures between 700 and 875°C. An ultrapure calcium carbonate sample with a mean size of 17 μm and a specific surface area of 0.43 m² g⁻¹ was used. From the sulfation tests some additives (Nab>2b>COb>3b>, Lib>2b>COb>3b>, Kb>2b>COb>3b>, Nab>2b>SOb>4b>, NaF, NaCl) enhanced the sulfation capacity and sulfation rate with respect to the undoped sample. All these additives correspond to alkaline compounds. The effect of additives on the decomposition of CaSOb>4b> in sulfated samples was also investigated. In this case nonisothermal experiments with a heating rate of 4 K min⁻¹ were performed in a COb>2b> atmosphere. The results indicate that presence of some additives has a catalytic effect on sulfate decomposition.