Rational methods for processing of chromia-alumina catalyst

The possibility to utilize one of the types of bulky wastes from oil refineries – spent chromia-alumina catalyst (SCAC) for dehydrogenation of low-molecular hydrocarbons – was considered. Methods for recycling of the spent catalyst were analyzed and implemented, namely, leaching with a NaOH excess, sintering with NaOH, and sintering of the catalyst with Na2CO3. Sintering with Na2CO3 was shown to be the most efficient method of SCAC processing because the stripping degree reached 92%. The alkaline filtrate treated with H2O2 was carbonized by carbon dioxide to recover Al2O3 with trace amounts of Cr. After evaporation of the chromate solution, sodium chromate containing 0.04-0.5% Al was recovered.