Pore Size and Adsorptive Capacity of Unburned Carbon Affected by Gasification with Carbon Dioxide

Abstract

Gasification of unburned carbon by using CO₂ gas at temperatures of 950–1100°C was performed, in order to modify the pore size distribution and adsorptive capacity of the carbon. Equipments such as N₂ adsorption apparatus, mercury pore size analyzer, and SEM were used, where yield, specific surface area and methylene blue number for adsorptive capacity, pore size, and appearance of the carbon were analyzed. Results show that gasification of unburned carbon produces larger adsorptive capability as well as a larger specific surface area. While reacting with CO₂ at 1100°C for 45 min, the methylene blue numbers reach to 54–154 mg/g, and the specific surface areas reach to 113–235 m²/g, which signify the actual utility. All carbons in gasification form new pores in a mutual size approximately 0.1–0.01 µm, whose majority affects the adsorptive capacity and specific surface area of the carbon. Besides, their group appearance complies with the obvious flow-like pattern, containing carbon ingredients with various degrees of crystallinity in the surface of unburned carbon. The new pore, conclusively, forms from the lower crystalline carbon ingredient that gasified with CO₂ earlier, in the flow-like pattern.

Keywords:

• Unburned carbon
• Gasification
• Adsorptive capacity
• Specific surface area
• Pore size

Acknowledgment

This work was supported by Ministry of Economic Affair, R.O.C. (Project No. 91-EC-17-A-10-S1-007).