V2O5/炭基材料用于烟气脱硫脱硝的研究进展

燃煤烟气污染是我国可持续发展需要重点解决的环境问题.目前国内外使用的均是偏离排烟温度的单一污染物控制技术,几种技术串连实现多种污染物排放控制的成本较高.炭基材料由于其独特的性质,不仅可在排烟温度范围脱除烟气主要污染物--硫、硝、汞等,而且可以实现这些污染物的同时脱除.活性焦作为较为廉价的炭基材料,已经在国外实现了工业应用.过去10余年的研究表明,V2O5/活性焦的脱硫、脱硝、脱汞活性显著优于活性焦自身,也优于其他金属氧化物改性的活性焦,有望成为新一代烟气污染物排放控制技术的核心催化剂.本文总结了过去10年中V2O5/活性焦的研究进展,重点展示了脱硫和脱硝过程中的原理性认识,得出V2O5的低温氧化性是其促进多种污染物脱除的共性原因.可以看出,我国在这方面的研发中做出了重要贡献,形成了系统、深入的研究成果.     

V2O5/TiO2基SCR脱硝催化剂的制备及其催化性能

采用纳米TiO₂为催化剂载体原料,V₂O₅为催化剂,通过混合、球磨、干燥和焙烧等工艺制备选择性催化还原脱硝法催化剂,研究了催化剂的制备工艺和催化性能。通过差热分析研究催化剂的相变和烧结温度,通过模拟烟气分析装置表征催化剂的催化性能。结果表明,加入V₂O₅可以提高催化性能,以6%V₂O₅-94%TiO₂为配方的催化剂对NO的脱除率达97.5%,温度窗口为（300～420） ℃。     

氨法选择性催化还原脱硝催化剂的研究

采用浸渍法,以TiO₂为载体,负载P₂ O₅、V₂O₅和MoO₃或WO₃制备选择性催化还原(SCR)催化剂,研究了不同磷含量以及水蒸汽对催化剂性能的影响。结果表明,随着催化剂中磷含量增加,P₂O₅-V₂O₅-MoO₃/TiO₂催化剂的SCR活性呈先上升后下降的趋势,其中,含质量分数0.5%P₂ O₅催化剂的活性较好。反应体系中水蒸汽的存在对催化剂的低温活性有明显的抑制作用。     

V2O5/Al2O3上异丁烷脱氢反应研究

用浸渍法制备了质量分数为12%V₂O₅/Al₂O₃负载型催化剂，考察了催化剂的活化气氛，反应中异丁烷与氢气的比例和反应温度对异丁烷脱氢活性的影响。结果表明，用N2作活化气，反应中异丁烷与氢气的体积比为1∶1时，在质量分数为12%的V₂O₅/Al₂O₃催化剂上异丁烷脱氢转化率和选择性较好，在625 ℃时，转化率达到52%，选择性为80%。     

三氟乙醇催化氧化合成三氟乙醛

研究了三氟乙醇催化氧化合成三氟乙醛的钒系催化剂。以V₂O₅为活性组分,考察了以ZrO₂为载体,并在此基础上通过添加MoO₃、SnO₂和WO₃等助催化剂进行性能调变。结果表明,以ZrO₂为载体, n（V₂O₅）∶n（ZrO₂）=5,SnO₂作为助催化剂,在反应温度290 ℃、空速0.33 h^-1和原料配比n（O₂）∶n(三氟乙醇）=11.69最佳工艺条件下,三氟乙醇转化率达89.06%,三氟乙醛选择性达97.14%。     

负载氧化钼催化剂催化氧化脱硫研究

浸渍法制备了MoO₃/TiO₂催化剂,并对其进行了X射线衍射以及拉曼光谱分析。以正辛烷为溶剂,二苯并噻吩为模型硫化物组成模拟油品,以MoO₃/TiO₂为催化剂（以MoO₃/Al₂O₃作对比）,在H₂O₂-CH₃COOH体系中对模拟油品的氧化脱硫进行了研究。考察了活性组分MoO₃负载量、氧化剂用量、乙酸用量、反应时间以及反应温度等因素对二苯并噻吩脱除的影响。实验结果表明,相对MoO₃/Al₂O₃,MoO₃/TiO₂具有更好的催化氧化脱硫性能;同时MoO₃负载量、乙酸加入量和过氧化氢加入量以及反应温度对二苯并噻吩的氧化脱除均有影响。     

SO2及水蒸汽对新型钒氧化物脱氮催化剂活性的影响

以TiO₂/Al₂O₃/堇青石蜂窝陶瓷为载体、V₂O₅-MoO₃-WO₃为活性组分，采用溶胶-凝胶法和浸渍法制备了用于氨法选择性催化还原烟气中NO的新型催化剂，考察了SO₂和水蒸汽对其脱氮活性的抑制作用。结果表明，SO₂和水蒸汽对其活性抑制不明显，催化剂在最佳温度仍然能保持90%的脱氮率。运用红外表征手段对活性抑制后的催化剂表面进行研究，发现有微量的硫酸盐生成。     

烟气脱硫活性炭纤维毡催化剂的研究

将活性炭纤维毡用浸渍法进行处理,实验确定的浸渍条件为：浸渍混合液中含NH₄VO₃ 质量分数为197%, CsNO₃质量分数为068%,浸渍液温度70 ℃,1 250 mL浸渍液浸渍活性炭纤维（ACF） 20 g,每次浸渍时间6 h,重复浸渍3次。随后在N₂保护下于250 ℃焙烧50 min,冷却至室温得到ACF催化剂。在实验室模拟试验装置上对ACF催化剂的烟气脱硫反应特性进行测试。实验结果表明,对烟气脱硫的反应活性次序为：KI-ACF＞V₂O₅-Cs₂O-ACF＞空白-ACF。并且在烟气中含 SO₂0.225 mol·m^－3,空速为2 400 h^－1,反应温度348 K,测取实验数据,回归得到烟气在V₂O₅-Cs₂O-ACF上脱除硫的反应动力学方程:dc_SO2/dt=0.072exp(－7.843×10³/RT)c_SO2^1.025·c_O2^0.579。     

溶胶-凝胶法制备掺杂型V2O5/TiO2脱硝催化剂

以十二胺表面活性剂为模板剂,钛酸四丁脂为无机母体源,采用溶胶-凝胶法制得稳定的TiO₂凝胶,经焙烧得到掺杂型V₂O₅/TiO₂脱硝催化剂粉末。分别用热重分析、X射线衍射、拉曼光谱和氮气吸附脱附法对催化剂进行了结构、比表面积和孔径的表征。在固定反应床,对氮氧化物的脱除活性进行了考察。结果表明,催化剂为锐钛矿,呈介孔结构,比表面积为118.5 m^₂·g^_-1,孔径（6～8） nm。钒以V=O键形式单层分布于TiO₂中。催化活性评价结果表明,制备的催化剂在空速10 000 h^-1和温度（180～450） ℃有较好的催化活性,空速对催化活性的影响主要在270 ℃以下。     

γ-Al2O3在CeO2-La2O3催化还原SO2中的作用

考察了反应温度对γ-Al₂O₃、CeO₂-La₂O₃和CeO₂-La₂O₃/γ-Al₂O₃催化CO还原SO₂到单质硫活性的影响。采用XRD表征了催化剂反应前后的物相变化。结果表明，温度过低或过高均不利于γ-Al₂O₃催化CO还原SO₂的反应。γ-Al₂O₃的介入提高了CeO₂和La₂O₃的分散性，使Redox 和COS两种反应机理在同一催化剂上的协同作用增强，使CeO₂-La₂O₃/γ-Al₂O₃在催化还原SO₂的反应中具有更低的反应温度和更高的活性。     

SO2 and NO removal from flue gas over V2O5/AC at lower temperatures — role of V2O5 on SO2 removal

Supporting V₂O₅ onto an activated coke (AC) has been reported to significantly increase the AC's activity in simultaneous SO₂ and NO removal from flue gas. To understand the role of V₂O₅ on SO₂ removal, V₂O₅/AC is studied through SO₂ removal reaction, surface analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FTIR) techniques. It is found that the main role of V₂O₅ in SO₂ removal over V₂O₅/AC is to catalyze SO₂ oxidation through a VOSO₄-like intermediate species, which reacts with O₂ to form SO₃ and V₂O₅. The SO₃ formed transfers from the V sites to AC sites and then reacts with H₂O to form H₂SO₄. At low V₂O₅ loadings, a V atom is able to catalyze as many as 8 SO₂ molecules to SO₃. At high V₂O₅ loadings, however, the number of SO₂ molecules catalyzed by a V atom is much less, due possibly to excessive amounts of V₂O₅ sites in comparison to the pores available for SO₃ and H₂SO₄ storage.     

O2/CO2气氛下煤燃烧SO2/NO析出特性

在水平管式炉上研究了O₂浓度、CO₂浓度、温度及石灰石添加等各参数对O₂/CO₂气氛下徐州烟煤和龙岩无烟煤燃烧过程中SO₂/NO排放特性的影响。结果发现,O₂/CO₂气氛下,烟煤和无烟煤燃烧SO₂/NO的析出规律与空气气氛下不同,同等O₂浓度下析出量比空气气氛下小。O₂/CO₂气氛下,随着O₂浓度的提高,烟煤和无烟煤SO₂/NO排放量均增大;随着CO₂浓度的升高, SO₂/NO排放量均减小。O₂/CO₂气氛下,石灰石添加对SO₂排放的抑制作用低于空气气氛下;石灰石添加对NO的排放有一定减排作用。对煤灰的元素分析显示O₂/CO₂燃烧对SO₂的抑制主要是由于煤灰的自固硫能力增强,而对NO的减排作用则是促进燃料N向其他含N气体的转换。     

负载型K2CO3/Al2O3二氧化碳吸收剂的碳酸化反应特性

The carbonation characteristics of K₂CO₃/Al₂O₃ supported sorbent for CO₂ capture was investigated with thermogravimetric apparatus（TGA）,X-ray diffraction（XRD）,scanning electron microscopy analysis（SEM）and N₂ adsorption.The results showed that the carbonation rate of K₂CO₃ before being loaded on Al₂O₃ was slow.However,the K₂CO₃/Al₂O₃ upported sorbent showed excellent carbonation performance.The difference in carbonation behavior between K₂CO₃ nd K₂CO₃/Al₂O₃ supported sorbent was analyzed from the microscopic view.The analytical reagent K₂CO₃ sample was of monoclinic crystal structure and could react quickly with H₂O in the experimental carbonation environment to produce K₂CO₃•1.5H₂O,which was unfavorable to carbonation reaction.When K₂CO₃was loaded on Al₂O₃,the surface area and porosity of the sorbent was improved greatly.So the carbonation properties of the K₂CO₃/Al₂O₃ supported sorbent was also improved.     

Gas-phase elemental mercury capture by a V2O5/AC catalyst

Gas-phase elemental mercury (Hg⁰) capture by an activated coke (AC) supported V₂O₅ (V₂O₅/AC) catalyst was studied in simulated flue gas and compared with that by the AC. The study on the influences of V₂O₅ loading, temperature, capture time and flue gas components (O₂, SO₂, H₂O and N₂) shows that the Hg⁰ capture capability of V₂O₅/AC is much higher than that of AC. It increases with an increase in V₂O₅ loading and is promoted by O₂, which indicates the important role of V₂O₅ in Hg⁰ oxidation and capture; it is promoted slightly by SO₂ but inhibited by H₂O; it increases with an increase in temperature up to 150 °C when Hg desorption starts. X-ray photoelectron spectroscopy analysis and sequential chemical extraction experiments indicate that the main states of Hg captured on V₂O₅/AC are HgO and HgSO₄. Temperature programmed desorption experiments were also made to understand the stability of the Hg captured.     

O2/CO2气氛煤焦的燃烧及其孔隙结构变化

采用热力工况与实际煤粉炉相近的沉降炉实验装置,制备了不同环境气氛下（O₂/N₂及O₂/CO₂气氛）、不同燃尽率的煤焦试样,并采用低温氮吸附仪和扫描电子显微镜测定了其孔隙结构和表面形貌。结果表明,在相同的操作条件下,相同O₂浓度的O₂/CO₂气氛下煤焦的燃烧速率较慢、燃尽率较低,各试样的孔比表面积和比孔容积均较小。两种气氛下燃尽过程孔结构参数（SBET和VBJH）均呈减小趋势,且在孔径变化较明显的区域内（<5 nm）在CO₂气氛下煤焦的孔径分布较小且与煤种相关。SEM图像显示CO₂气氛下的煤焦表面致密,孔隙较少,其定性结果与N₂吸附法的定量测量结果吻合较好。     

US/H2O2系统协同降解苯酚的动力学研究

超声波/过氧化氢（US/H₂O₂）复合氧化过程在废水处理领域有很广泛的应用前景，但在动力学方面的研究很少，为此研究了US/H₂O₂工艺降解苯酚的动力学.结果表明，苯酚在单独超声波辐射（US）、过氧化氢（H₂O₂）氧化和超声波/过氧化氢（US/H₂O₂）协同下的降解均符合表观一级动力学.在单独的超声波辐射或者过氧化氢氧化下苯酚去除率很小，而在复合氧化过程US/H₂O₂工艺中有显著的提高，表明协同效应存在.苯酚去除的速率常数增强因子可达到6.904.进一步从US/H₂O₂系统中存在US、H₂O₂和羟基自由基（&#8226;OH）3部分协同作用的降解机理，推导出了简化的机理动力学模型，很好地反应过氧化氢浓度过量条件下苯酚的降解.     

辉光放电等离子体增强制备甲烷催化燃烧的高分散Pd/Al2O3催化剂

A novel Pd/Al₂O₃ catalyst prepared by glow discharge plasma technology is reported.The results of H₂-chemisorption indicate that palladium dispersion of the plasma-prepared Pd/Al₂O₃ reaches 29.7%,which is about 5 times higher than Pd/Al₂O₃ prepared by conventional preparation.Meanwhile,the particle diameter of the plasma-prepared catalyst is 3.8 nm, but the particle diameter of the conventional catalyst is 20.4 nm.Such plasma-prepared Pd/Al₂O₃ catalyst shows a higher activity for catalytic combustion of methane than the conventional catalyst.Methane conversion reaches 90% at 400 ℃, but it is only near 30% for the conventional catalyst at the same temperature.     

TiO2-V2O5纳米纤维光催化氧化烟气中的Hg0

对静电纺丝法制备的TiO₂和TiO₂-V₂O₅纳米纤维进行光催化脱除模拟烟气中Hg⁰的研究。对纳米纤维进行了SEM、TEM、XRD、BET和UV-Vis检测。结果表明TiO₂-V₂O₅纳米纤维为锐钛矿,V₂O₅高度分散在TiO₂中。纤维直径在200 nm左右,由粒径为10 nm左右的微粒组成。掺杂V₂O₅后,纤维的吸光范围扩大,在可见光范围内的吸光度比纯TiO₂时有了很大提高。实验研究了不同光照条件、V₂O₅的掺杂量和循环次数对脱汞的影响,分析了TiO₂-V₂O₅催化脱汞的机理。当V₂O₅的质量含量为3%时,TiO₂-V₂O₅在可见光下的脱汞率可达到66%,比纯TiO₂时的7%有了显著提高;纤维的脱汞性能稳定,多次循环后紫外光和可见光下的脱汞率仍分别保持在80%和65%左右。电子的跃迁和电子、空穴的快速分离是TiO₂-V₂O₅在可见光下脱汞率提高的主要原因。     

Elemental sulfur production through regeneration of a SO2-adsorbed V2O5-CoO/AC in H2

H₂ regeneration of an activated carbon supported vanadium and cobalt oxides (V₂O₅-CoO/AC) catalyst–sorbent used for flue gas SO₂ removal is studied in this paper. Elemental sulfur is produced during the H₂-regeneration when effluent gas of the regeneration is recycled back to the reactor. The regeneration conditions affect the regeneration efficiency and the elemental sulfur yield. The regeneration efficiency is the highest at 330 °C, with SO₂ as the product. The production of elemental sulfur occurs at 350 °C and higher with the highest elemental sulfur yield of 9.8 mg-S/g-Cat. at 380 °C. A lower effluent gas recycle rate is beneficial to elemental sulfur production. Intermittent H₂ feeding strategy can be used to control H₂S concentration in the gas phase and increase the elemental sulfur yield. Two types of reactions occur in the regeneration, reduction of sulfuric acid to SO₂ by AC and reduction of SO₂ to elemental sulfur through Claus reaction. H₂S is an intermediate, which is important for elemental sulfur formation and for conversion of CoO to CoS that catalyzes the Claus reaction. The catalyst–sorbent exhibits good stability in SO₂ removal capacity and in elemental sulfur yield.     

沉淀法SiO2包覆纳米CaCO3吸附剂性能

以CO₂为沉淀剂,Na₂SiO₃为硅源,制备了SiO₂包覆纳米CaCO₃吸附剂。TEM测试证实纳米CaCO₃表面包覆一层SiO₂膜, 用SEM & EDX 测试5个包硅样品Si含量为0.67%～4.93%。采用TGA考察吸附剂的分解温度及600℃、20% CO₂条件下的吸附性能。结果表明：采用CO₂沉淀法包覆SiO₂后,与未包硅的纳米CaCO₃相比,分解温度降低9～42℃。纳米SiO₂/CaCO₃吸附剂的循环吸附率、吸附容量、吸附速率均随Si含量的减小先增加后降低。Si含量为1.05%的纳米SiO₂/CaCO₃吸附剂显示最佳吸附性能,第1、5次循环吸附容量分别为8.9、6.0 mol·kg^-1,与未包覆SiO2的纳米CaCO₃相比,分别提高11%、50%,同时在第5次循环快反应段吸附速率较纳米CaCO₃提高10%。与纳米CaCO₃相比,包硅后的吸附剂具有较高的吸附容量和循环吸附率,循环稳定性较好。