【作者】 刘树青；

【导师】 刘振宇； 刘清雅；

【作者基本信息】 北京化工大学 ， 化学工程， 2009， 硕士

【摘要】 燃煤烟气污染已成为制约我国社会经济可持续发展的重要因素,烟气脱硝是解决其中氮氧化物污染问题的重要技术手段。活性炭烟气脱硝技术可在锅炉排烟温度下操作,烟气无需再热,是适合我国国情的烟气脱硝新技术。目前在烟气脱硝技术中应用较多的活性炭材料是颗粒状活性炭,这种炭材料在实际操作中最突出的问题是床层压力大、抗粉尘堵塞能力弱。因此开发新型活性炭对解决现行炭法烟气脱硝技术中存在的问题具有重大的意义。蜂窝状活性炭是一种新型的活性炭,其最大的优点是流体力学性能好,在烟气脱硝领域中具有广阔的应用前景。本文创造性地开发了以煤为主要原料,添加煤焦油兼作为低温和高温黏结剂,不加其他任何添加剂,通过物料混合、真空练泥、整体挤出成型、干燥、炭化、水蒸汽活化等工序制备蜂窝状活性炭的新工艺,采用变形度测试、N₂吸附、抗压强度测试等表征手段,研究了煤泥制备、挤出成型工艺参数、炭化和活化条件对最终蜂窝状活性炭外形结构的变化、孔隙结构以及机械强度的影响规律,并探讨了煤基蜂窝状活性炭作为催化剂载体在催化还原烟气中氮氧化物（NO_x）的可行性,为实现蜂窝状活性炭在烟气脱硝中的工业化提供了理论基础。有关实验及主要结果如下:1.煤焦油与煤粉通过整体挤出成型法能够得到蜂窝坯体。文献认为,水溶性有机粘合剂能够提高煤粉泥料的可塑性,可避免煤基蜂窝坯体在干燥过程中开裂现象的发生;润滑剂的加入能够减少煤粉泥料与模具之间的摩擦阻力,两者被认为是煤基蜂窝挤出成型必不可少的成分。事实上,流动性良好的低温煤焦油具有上述两者的功能,采取合适的工艺可以与煤制备出性能优异的蜂窝状活性炭。2.微波干燥是保持蜂窝坯体结构完整性的重要手段。3.在相同炭化温度不同炭化升温速率下得到的蜂窝半焦收缩率无明显差异,蜂窝半焦的收缩率取决于炭化温度;而蜂窝半焦的径向弯曲率与炭化温度和炭化升温速率均无明显关联。4.活化温度和活化时间显著影响蜂窝状活性炭的孔隙结构和机械强度。随着活化时间的增加,蜂窝状活性炭总孔容增大,机械强度降低。5.负载V₂O₅后硫化处理是提高煤基蜂窝状活性炭低温脱硝活性的有效手段。当烟气中存在SO₂时,反应生成的H₂SO₄及硫酸氨盐沉积在活性炭孔隙中,覆盖了活性点,造成有效比表面积降低,使得脱硝活性快速下降。切断SO₂后,脱硝活性缓慢上升但不能完全恢复,并且之后相当长一段时间内有SO₂逸出,说明脱硝活性的下降起源于SO₂在载体上的吸附,由SO₂吸附引起的这部分活性的降低能够恢复。更多还原

【Abstract】 The pollution of NO_x from flue gas has become a critical factor that restricts the development of economy and society in China.It is very important to find flue gas DeNO_x technology to solve the problem of NO_x pollution.DeNO_x technology by activated carbon can be operated under the temperature of flue gas,the flue gas need no reheating,which make it fit the situation of our country.Granule activated is the main materials used in the flue gas DeNO_x in recent years.Its shortcoming is that it has high pressure drop and bad anti-dust blocking ability when used in packed bed.So exploiture a new activated carbon material have great significance in solving questions which exists in current technology of flue gas DeNO_x.Activated carbon honeycomb is a new activated carbon,which has good hydrodynamic performance.So this material has bright prospect in flue gas DeNO_x.In this dissertation,a series of ACH was prepared through bulk extrusion of a kind of anthracite and coal tar,followed by carbonization and activated in steam.In this technology,coal tar is used as the adhesive and no other organic additive is added.The properties of ACH were characterized by nitrogen adsorption,deformation、shrinkage test and mechanical strength test.Activity of ACH supported V₂O₅ catalyst in selective catalytic reduction of nitric oxide with ammonia was also studied.All the results can offer some theoretics bases for realizing industrial application of activated carbon honeycomb in the field of flue gas DeNO_x. Relative experiments and the main results are listed below.1.ACH monoliths were prepared by extruding of a mixture of anthracite and coal tar.In previous work,the water-soluble organic adhesive and lubricating oil were thought to be necessary additives in extrusion of coal-based honeycomb.In this work,we use coal tar which has good liquidity as the only adhesive to prepare ACH monoliths.2.Microwave drying is an important way to maintain the structural integrity of the honeycomb monoliths.3.The semi-coke under the same carbonization temperature but different carbonization heating rate have no significant difference in contraction,the shrinkage rate of char depends on the carbonization temperature.The carbonization temperature and carbonization heating rate have no significant associated with radial bending of semi-coke.4.Activation temperature and activation time have a great impact on the pore structure and mechanical strength of coal-based ACH.With the increase in activation time,the total pore volume of activated carbon honeycomb increases,lower mechanical strength.5.The SCR activity of ACH catalyst can be improved by supporting V₂O₅ and further sulfating treatment.The NO conversion would be suddenly drop in the present of SO₂,which results from pore plugging from deposition of ammonium-sulfate salts such as NH₄HSO₄ and（NH₄）₂S₂O₇ on the catalyst surface formed by SO₂ oxidation.The SCR activity can be partly resumed after SO₂ is cut off,we also found SO₂ in the out gas.From the phenomena, we can conclude that the reduction of NO conversion is caused by the adsorption of SO₂ on the surface of the catalyst,which can be removed out.更多还原