High-Temperature Reaction of Kaolin with Sulfuric Acid

• Published in: Industrial & engineering chemistry research Vol. 41; no. 17; pp. 4168 - 4173
• Main Authors: Colina, Fernando G, Esplugas, Santiago, Costa, Jose
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 21.08.2002
• Subjects: Chemistry; Exact sciences and technology; Inorganic chemistry and origins of life; Kinetics and mechanism of reactions; Conversion rate; Reaction product; Specific surface area; High temperature; Experimental study; Sulfuric acid; Characterization; Inorganic acids; Aluminium Sulfates; Chemical reaction; Reaction mechanism; Kinetics; Kaolin
• ISSN: 0888-5885; 1520-5045
• DOI: 10.1021/ie010886v

A new procedure is described in which kaolin and a small amount of concentrated sulfuric acid are heated in a furnace at temperatures between 150 and 1000 °C. Parameters studied were reaction temperature and time, proton to alumina molar ratio, calcination temperature and time, and amount of water in the reaction medium. Al yield grew sharply until reaching a maximum at a reaction temperature of 700 °C and decreasing sharply beyond this temperature. Ti reaction yield values were lower than the Al reaction yield, showing a maximum at 200 °C and decreasing steadily as the reaction temperature was increased. Fe reaction yield showed a maximum in the same range of reaction temperature as Al. Previous calcination of kaolin produced only slight increases in reaction yields. Brunauer−Emmett−Teller (BET) surface area tests indicated an increase of the BET surface area for short reaction times, reaching values above 100 m2/g. Products of the reaction were mostly Al2(SO4)3.