改性半焦烟气脱硫的机理研究

THE MECHANISM OF MODIFIED SEMICOKE IN PROCESS OF SO_2 REMOVAL FROM FLUE GASES

本文对海拉尔褐煤半焦及其水蒸气活化和高温氧化改性后的烟气脱硫性能进行了研究,通过苹甲酸和联苯胺吸附、元素分析、BET和XPS测试,在2%O_2+N_2,720℃—770℃,1—2h条件下,改性的半焦是理想的烟气脱硫吸附剂,其脱硫能力比未处理半焦及水蒸气活化半焦强.改性后半焦氧含量增加.表面碱性基团增加,表面酸性基因减少 高温氧化改性半焦的比表面积有所增加,但比水蒸气活化半焦的比表面积少得多 半焦表面具有C—O—C(弱碱性),O=C—O—C=O(酸性),—C—O—C—O—C—(强碱性)和=C=O(碱性)几种表面含氧基团.其中—C—O—C—O—C—是SO_2在半焦表面的活性吸附位 高温氧化改性可显著增加SO_2活性吸附位的比例.

A semicoke from a pilot for Hailaer lignite pyrolyzed is modified by steam activation or thermal oxidation. The properties of the modified semicoke are investigated by adsorption of SO2 from flue gases, benzoic acid and benzidine adsorption, element analysis, BET and XPS analysis. Results show that the semicoke treated under 2%O2+N2, 720℃-750℃,1-2 hours is an ideal adsorbent for SO2 removal from flue gases, the oxygen content of thermal oxidization semicoke increases, surface basic oxide groups increase with rising of thermal oxidation temperature, whereas surface acid oxide groups decrease, the BET specific surface area of thermal oxidation semicoke is several tens m2 @ g-1', much lower than that of steam activation semicoke, several surface oxides including C-O-C(weak basic oxide),O=C-O-C=O(acid oxide),-C-O-C-O-C ( strong basic oxide ) are produced in thermal oxidization semicoke, the oxide -C-O-C-O-C-is the active site of SO2 adsorption.