Preparation of activated carbon from Canadian coals using a fixed-bed reactor and a spouted bed-kiln system

Abstract

Several western Canadian coals (Bienfait lignite, Roselyn, Montgomery, Atlas-Century and Egg Lake subbituminous coals, and Coal Valley and Smoky River bituminous coals) were activated with steam to produce granular activated carbons. Activation times and temperatures were 0.5–4.0 h and 650–850°C. The iodine number was used as a primary indicator of product quality. Activated carbons having iodine numbers of ≥ 500 mg g −1 carbon were produced from each coal except Smoky River. Bienfait lignite was found to be relatively reactive, the highest iodine number developed being 545 at a yield of 29 wt% and at 650°C. Products from Montgomery and Atlas-Century coals showed iodine numbers of 620 and 579 at yields of 36 and 37 wt% respectively, at 700°C. When activated at 650°C for 3 h, Roselyn coal gave a product with an iodine number of 730. The products from Coal Valley coal, the least reactive, had an iodine numbers which increased from 370 on activation at 650°C for 2 h to 571 on activation at 760°C for 1.0 h, the product yield decreasing from 59 to 45 wt%. The high ash of the products, 23–67 wt%, limits their quality. The performances of fixed-bed and spouted bed-kiln reaction systems were compared by analyses of the properties of the products from Coal Valley coal. The fixed-bed system generally gave products with higher sorptive capacities under operating conditions which caused higher carbon burnoff.