THE INFLUENCE OF MODIFICATIONS TO THE SURFACE GROUPS OF BROWN COAL CHARS ON THEIR FLUE-GAS CLEANING ABILITY

The preparation and performance of brown coal derived chars for flue gas desulphurization and denitrogenation were investigated. Starting materials were a commerical char produced from Yallourn briquettes and a high surface area active carbon produced from Loy Yang brown coal by potassium hydroxide treatment. It was found that modification of the commercial Yallourn char surface functionalities via sulphuric acid activation followed by ammonia treatment at 673 K produced a carbon with a higher denitrogenation activity than that of polyacrylonitrile-based active carbon fibre (PAN-ACF) and 60% of the desulphurization ability of the most active PAN-ACF. The high surface area Loy Yang carbon did not produce any significant increase in denitrogenation activity after identical pretreatment. This behaviour is believed to result from the low chemical reactivity of the high surface area carbon towards the pretreatment process.