摘要
以生物质稻壳为原料,采用CO2,H3PO4活化方法,并经NH4Br溶液改性,分别制备了稻壳热解焦、活化焦和改性焦,并将其作为脱汞吸附剂.采用N2吸附/脱附、SEM-EDS、FTIR等方法研究吸附剂的微观物理化学特性,结果表明:CO2活化使稻壳焦的孔隙结构显著改善,增强了吸附剂对汞的物理吸附能力;H3PO4活化使稻壳焦表面生成大量酸性含氧官能团,有利于汞的化学吸附;NH4Br改性使Br元素有效负载到稻壳焦表面,促进了单质汞向氧化态汞的转化.固定床汞吸附实验结果表明:改性后的稻壳热解焦与活化焦的脱汞效率分别提高了60%与90%,实验120min后,CO2,H3PO4活化改性焦的汞吸附效率仍分别保持在90%与80%以上.生物质稻壳经CO2/H3PO4活化和NH4Br溶液改性后可作为燃煤电厂烟气喷射脱汞的廉价高效吸附剂.
Rice husk was pyrolyzed,activated by CO2 and H3 PO4 and modified by NH4 Br separately to prepare rice husk char,rice husk activated char and rice husk modified char as sorbents for remov-al of mercury.Microstructures of the prepared rice husk chars were characterized based on instru-mentations of nitrogen adsorption,SEM-EDS （scanning election microscope energy dispersive spec-trometer）and FTIR （Fourier transform infrared）.The experimental results indicate that CO2 activa-tion benefits a more developed microporous structure with higher physisorption capacity;H3 PO4 acti-vation produces a large number of surface acidic oxygen functional groups on the surface of rice husk chars,which are beneficial for the mercury chemisorption;As shown in the EDS spectrum after trea-ted by NH4 Br,bromine is loaded on the rice husk char surface,indicating that elemental mercury will be easily transformed into the oxidized state.Mercury adsorption capacity was evaluated in a fixed bed.The results are summed as follows：after modification,the Hg0 removal efficiency of the rice husk pyrolyzed char is improved over 60% while the activated char is increased by 90%.The mercury adsorption efficiency of CO2 and H3 PO4 activated cokes remains above 90% and 80%,re-spectively,after 120 min of adsorption.The modified CO2 and H3 PO4 activated rice husk chars can be used as the high-efficient and low-cost sorbents for the demercuration process of activated carbon injection applied in coal-fired power plants.
出处
《东南大学学报（自然科学版）》
EI
CAS
CSCD
北大核心
2014年第2期321-327,共7页
Journal of Southeast University：Natural Science Edition
基金
国家自然科学基金资助项目(51376046
51076030)
江苏省环保科研课题基金资助项目(201113)
江苏省产学研联合创新资金资助项目(BY2013073-10)
江苏省研究生科研创新计划资助项目(CXZZ13_0093)
中央高校基本科研业务费专项资金资助项目
关键词
活化
改性
稻壳焦
脱汞
吸附剂
activation
modification
rice husk char
mercury removal
sorbent
