金属改性对SAPO-34低温还原NO性能的影响

采用浸渍法制备金属改性SAPO-34分子筛催化剂,分析比较了不同单金属（Cu或Co）及不同比例双金属（Cu：Co=1：1、3：1、5：1,质量比）改性催化剂对NO的催化还原性能,评价了不同催化剂的N₂选择性,并采用扫描电子显微镜（SEM）、比表面积测试、X射线衍射分析（XRD）、NH₃-程序升温脱附（NH₃-TPD）等表征手段对催化剂的物化性能进行了分析.结果表明,单金属Cu改性催化剂具有较宽的温度区间,在250~450℃范围内NO的转化率始终保持在100%;双金属改性使NO转化率保持为100%的最低温度下降了25~50℃,显著拓宽了低温段窗口,其中,Cu₃Co₁/SAPO-34催化剂的低温催化还原性能最好,200℃即可实现100%的NO转化率,175℃下的转化率也高达80%以上.Cu-Co双金属改性SAPO-34分子筛催化剂具有优异的低温催化还原NO性能,具有在机动车尾气、工业废气的低温脱硝治理领域应用的潜力.     

改性钒基整体式催化剂的制备及其对燃煤烟气中甲苯与一氧化氮的同步去除性能

采用工业上简易可行的单组分浸渍法和多组分浸渍法制备了一系列Cu/Fe/Mo改性的钒钛基整体式催化剂,考察了不同整体式催化剂制备工艺及浸渍液浓度对催化剂在模拟燃煤烟气中对甲苯和NO同步去除的性能,并优选出适应燃煤烟气的改性催化剂制备工艺及配方.结果表明,使用单组分浸渍法制备的浸渍液浓度为0.5%的Fe改性钒钛基整体式催化剂具有最优的活性和选择性,在350℃下对甲苯和NO的转化率分别达到99%和94.9%,对CO_x和N₂的选择性分别为88%和96.4%,XRD和SEM-EDS-Mapping结果表明,改性组分（Cu/Fe/Mo）均匀分散在钒基整体式催化剂表面,Fe改性材料具有最大的比表面积和孔容,因而可提高甲苯和NO的同步脱除性能.     

汽车尾气净化催化剂Ag/SAPO-34选择性催化还原NO

评价了Ag/SAPO-34分子筛催化剂选择性还原NO的活性,并运用漫反射红外光谱原位研究NO在Ag/SAPO-34催化剂上的选择性催化还原机理.结果表明Ag/SAPO-34有良好的低温活性,在氧气浓度为3.6%和温度为573K～673K时NO还原成N2的转化率达70%;催化剂活性随C3H6浓度的增加而升高,随空速的增加而稍有下降.基于漫反射红外光谱,认为反应机理为:NO、丙烯和氧反应,在Ag/SAPO-34催化剂上生成吸附的有机-氮氧化物,再由这些吸附物种分解成N₂,催化还原的关键是形成有机-氮氧化物中间体.氧的作用是充分促进丙烯活化以及增加NO_x吸附态含量,并且氧的存在是有效产生一系列中间物不可缺少的条件.     

六氨合钴溶液治理NO废气污染研究

将可溶性钴盐溶解在氨水溶液中生成六氨合钴离子([Co(NH₃)₆]²⁺),利用[Co(NH₃)₆]²⁺能络合NO和活化氧分子的特性,实现NO的吸收和氧化同时进行,从而将NO从废气中脱除掉并转化为硝酸根和亚硝酸根.用活性炭作催化剂实现[Co(NH₃)₆]²⁺离子的再生,保持[Co(NH₃)₆]²⁺溶液能长时间高效率地脱除废气中的NO.研究结果表明:用活性炭催化还原[Co(NH₃)₆]³⁺的转化率随着温度的升高而增大;在固定床催化反应器中,活性炭颗粒的大小对催化效果的影响不大;[Co(NH₃)₆]²⁺溶液能有效地脱除废气中的NO,废气中的氧有利于NO的脱除,采用活性炭催化再生[Co(NH₃)₆]²⁺后,0.02mol/L[Co(NH₃)₆]²⁺溶液脱除NO的效率能长期保持在80%以上.该法是一种经济、高效、简便的NO污染治理方法.     

钙钛矿LaMnO3负载贵金属在催化氧化碳烟中的作用

采用共沉淀法制备钙钛矿LaMnO₃,并用浸渍法在LaMnO₃上负载不同的贵金属得到系列催化剂.利用程序升温氧化反应对催化剂催化氧化碳烟的性能进行了测试.程序升温还原(H₂-TPR)、BET、XRD、SEM和FT-IR等表征手段对催化剂进行了表征.结果表明,当Pd的负载量在0.5%时,催化剂Pd/LaMnO₃的催化性能最好,和单独的LaMnO₃相比,最高燃烧速率温度降低了40℃.当负载量较小和较多时,碳烟起燃温度反而会比LaMnO₃高.在5种贵金属负载的催化剂中,其中Pd催化性能最好,依次为Au、Ru、Pt和 Rh.TPR测试表明贵金属的负载有助于钙钛矿中Mn⁴⁺的还原,对高温时Mn³⁺的还原作用不大.XRD衍射角向低角度出现了少许偏移,显示负载在表面的贵金属部分进入钙钛矿LaMnO₃的晶格结构中,使其晶粒增大;BET和SEM结果表明催化剂在反应后出现了轻微团聚现象.IR图谱显示反应前后,主要特征红外吸收带没有明显变化, 表明催化剂具有较好的结构稳定性.适量的贵金属在钙钛矿LaMnO₃上负载,能够有效地提高催化燃烧碳烟的活性.     

低温条件下Nano-MnOx上NH3选择性催化还原NO

采用流变相法制备了无载体Nano-MnO_x催化剂,在低温条件下(50～150℃)以NH₃为还原剂系统考察了氮氧化物的选择催化还原特性.结果表明,流变相法制备的Nano-MnO_x催化剂具有良好的低温催化活性.实验条件下,80℃即可获得98.25%的NO转化率,100～150℃内NO几乎完全转化;SO₂和H₂Ｏ会与NO和NH₃在催化剂表面产生竞争吸附,导致催化活性下降,但该影响是可逆的.经分析,较大的比表面积和较低的晶化度是Nano-MnO_x具有良好低温活性的2个主要原因.     

CO还原NO海泡石铜族金属催化剂的研究

以改性海泡石为载体,负载IB族金属(Cu,Ag,Au),制备CO还原NO的催化剂.用正交实验确定载体海泡石的改性条件.研究考察该催化剂在有氧条件下的催化还原性能,并用XRD、TGA、H2 TPR、BET等对该催化剂进行表征.研究发现,在有氧条件下,IB族金属(Cu,Ag,Au)催化剂中,Cu 海泡石对CO还原NO反应的催化活性最好;Cu负载量为5%、灼烧温度为400℃的催化剂表现出较高的活性;Cu 海泡石催化剂中加入Ce和Sm可以改善催化剂的性能.在实验条件基本相同的情况下,Cu 海泡石的催化活性好于Cu ZSM 5催化剂.     

以堇青石蜂窝陶瓷为载体的新型钒氧化物脱氮催化剂研究

以TiO₂/Al₂O₃/堇青石蜂窝陶瓷为载体,以V₂O₅-MoO₃-WO₃为活性组分,用于氨法选择性催化还原烟气中NO的新型催化剂,并对该催化剂的活性性能和微观结构进行了评价和表征.同时,将该催化剂的活性性能与其它几种活性组分相同但载体、制备方法、结构不同的催化剂进行了对比.对比结果表明,该新型催化剂能取得最好的选择性催化还原氮氧化物催化性能BET、FT IR、XPS表征实验结果表明,其高催化活性得益于大比表面积及大孔体积,而TiO₂/Al₂O₃/堇青石蜂窝陶瓷载体及其制备方法对获得好的催化剂构型起了至关重要的作用.     

掺杂La或Si对Ag/Al2O3催化剂热稳定性和脱NO活性的影响

利用 BET比表面测定和 X-射线衍射技术考察了掺杂 La或 Si的 Ag/Al₂O₃催化剂的热稳定性 ,并研究了富氧条件下 ,丙烯在这些催化剂上选择性还原 NO的活性 .结果表明 ,掺杂 La或 Si能抑制 Al₂O₃相变 ,使 γ-Al₂O₃完全转化为 α-Al₂O₃的温度升至 1100℃以上 .相应地 ,延缓催化剂比表面下降 ,从活性角度来看 ,当焙烧温度为 1100℃时 ,与掺杂 La或 Si相比 ,不掺杂 La或 Si的 Ag/Al₂O₃催化剂活性要低得多 ;当焙烧温度低于 1000℃时 ,掺杂少量 La(2 % La₂O₃)对 Ag/Al₂O₃催化剂活性影响不大 ,但是 ,掺杂 Si(2%或 8% SiO₂)或较高含量 La(8% La₂O₃)会导致催化剂活性降低 .综合考虑热稳定性和富氧条件下的 NO还原活性 ,认为掺杂较低含量 La(2% La₂O₃)的 Ag/Al₂O₃催化剂性能最佳 .     

Ce/Zr系列催化剂上碳颗粒物燃烧行为

分别在TG和TPO上考察了CeO₂,ZrO₂及不同Ce/Zr比的CexZr1-xO₂固溶体催化剂上soot的燃烧性能,同时考察了反应气氛对活性的影响.结果表明:Ce基催化剂能明显降低soot的起燃温度,Ce/Zr比的不同导致Ce_xZr_1-xO₂催化剂性能的差异.反应的速度控制步骤随O₂浓度的不同而改变;H₂O对Ce_0.5Zr_0.5O₂上soot的氧化活性基本没有影响;由于NO氧化产生的NO₂具有更强的的氧化能力,因此NO对soot的燃烧具有促进作用,起燃温度降低了30℃.催化剂上的β氧种参与了soot燃烧过程.     

Integrated removal of NO and mercury from coal combustion flue gas using manganese oxides supported on TiO2

A catalyst composed of manganese oxides supported on titania(MnO_x/TiO_2) synthesized by a sol–gel method was selected to remove nitric oxide and mercury jointly at a relatively low temperature in simulated flue gas from coal-fired power plants. The physico-chemical characteristics of catalysts were investigated by X-ray fluorescence(XRF), X-ray diffraction(XRD), and X-ray photoelectron spectroscopy(XPS) analyses, etc. The effects of Mn loading,reaction temperature and individual flue gas components on denitration and Hg~0 removal were examined. The results indicated that the optimal Mn/Ti molar ratio was 0.8 and the best working temperature was 240°C for NO conversion. O_2 and a proper ratio of [NH_3]/[NO]are essential for the denitration reaction. Both NO conversion and Hg~0 removal efficiency could reach more than 80% when NO and Hg~0 were removed simultaneously using Mn0.8 Tiat 240°C.Hg~0 removal efficiency slightly declined as the Mn content increased in the catalysts. The reaction temperature had no significant effect on Hg~0 removal efficiency. O_2 and HCl had a promotional effect on Hg~0 removal. SO2 and NH_3were observed to weaken Hg~0 removal because of competitive adsorption. NO first facilitated Hg~0 removal and then had an inhibiting effect as NO concentration increased without O_2, and it exhibited weak inhibition of Hg~0 removal efficiency in the presence of O_2. The oxidation of Hg~0 on Mn O x/TiO_2 follows the Mars–Maessen and Langmuir–Hinshelwood mechanisms.     

非热等离子体结合CuO催化剂或Ca(OH)2吸收剂去除氮氧化物

采用非热等离子体结合催化或现场化学吸收的2种方法来去除气流中的NO_x.结果表明,非热等离子体结合催化,反应器内的CuO催化剂能有效地促进NO的还原反应;相对于催化还原NO而言,脉冲电晕作用下能有效地降低NO催化还原的反应温度.当催化剂为CuO,脉冲电压为18kV,反应温度为200℃,还原剂为1%CO及NO进口浓度为719 mg/m³条件下,NO的去除率达到了100%.非热等离子体结合现场化学吸收方法,是一种在常温下从气流中净化氮氧化物的有效方法,NO的去除率远远高于反应器内没有吸收剂的情况.可以认为反应器内的Ca(OH)₂吸收剂通过与NO的氧化产物NO₂或NO₃的吸收反应促进了NO的去除.当反应器内有Ca(OH)₂吸收剂存在时,在脉冲电压为18kV,O₂浓度为2%及NO进口浓度为1 050 mg/m³条件下,NO的去除率达到了100%.     

废茶活性炭脱硫脱硝性能的应用研究

为探讨废茶活性炭对于SO2和NO脱除作用的制约因素,分别考察了材料孔径结构、石墨化程度及表面结构对其脱硫脱硝性能的影响,同时研究了其吸附机制及动力学过程.结果表明,较高的石墨化程度是影响材料脱硫性能的主要因素,微孔径较小且含氮碱性基团较高时有利于SO2的脱除;发达的中孔结构是制约NO脱除效率的关键因素,含氮碱性基团对NO的脱除具有一定的促进作用;烟气中SO2和NO共存时,材料的脱硫脱硝性能均有所降低,氧气和水蒸气的加入能够改善其脱硫脱硝效率;废茶活性炭在无水环境下对于SO2和NO的吸附作用均以物理吸附为主,水蒸气的存在促进了材料对SO2的化学吸附;通过动力学模型的拟合发现,Bangham吸附模型能够很好地描述材料脱硫脱硝的动力学过程,其R2均高于0.989,材料对于SO2和NO的吸附速率常数均随氧气和水蒸气的加入而减小.     

Effect of preparation parameters on catalytic properties of Pt/graphite

Catalytic ozonation of aqueous solutions of oxalic acid was examined in the presence of graphite-supported platinum catalysts. The catalytic activity of graphite was significantly enhanced by loading platinum. The removal efficiency of oxalic acid was 3.0%, 47.6% and 99.3% for ozonation alone, graphite catalytic ozonation and Pt/graphite catalytic ozonation in 30 min under the experimental condition, respectively. The influence of support pretreatment, solvent, impregnation time, platinum loading amount and reduction temperature on the activity of Pt/graphite catalyst was investigated. The pretreatment of graphite support had no effect on activity improvement of Pt/graphite catalyst. Solvent and impregnation time also no great effect on the activity. Platinum loading amount and reduction temperature influenced the catalyst activity significantly. The optimal catalytic performance of Pt/graphite was obtained when 1.0% platinum loading and 623 K of reduction temperature was adopted. The Pt/graphite catalyst was used for five times with no significant decrease in its activity and more than 90% oxalic acid removal was obtained. __________ Translated from Environmental Science, 2007, 28(6): 1258–1263 [译自: 环境科学]     

生物法废气脱硝研究

将城市生活污水处理厂活性污泥中的反硝化细菌培养挂膜到填料塔中,进行从模拟废气中脱除ＮＯｘ的效果性能实验研究,该生物膜填料塔能有效地脱除废气中的ＮＯｘ,ＮＯ２的去除率可达９９％以上,ＮＯ的去除率可达９０％左右。该法最适宜的温度为３０￣４５℃,进口ＮＯ浓度（５０￣５００ｍｇ／ｍ＾３）对其去除率几乎没有影响,随着废气流量的增加,ＮＯ的去除率逐步降低。     

Characterization and performance of Pt/SBA-15 for low-temperature SCR of NO by C3H6

Pt supported on mesoporous silica SBA-15 was investigated as a catalyst for low temperature selective catalytic reduction(SCR) of NO by C 3 H 6 in the presence of excess oxygen.The prepared catalysts were characterized by means of XRD,BET surface area,TEM,NO-TPD,NO/C 3 H 6-TPO,NH 3-TPD,XPS and 27 Al MAS NMR.The effects of Pt loading amount,O 2 /C 3 H 6 concentration,and incorporation of Al into SBA-15 have been studied.It was found that the removal efficiency increased significantly after Pt loading,but an optimal loading amount was observed.In particular,under an atmosphere of 150 ppm NO,150 ppm C 3 H 6,and 18 vol.% O 2,0.5% Pt/SBA-15 showed remarkably high catalytic performance giving 80.1% NOx reduction and 87.04% C 3 H 6 conversion simultaneously at 140°C.The enhanced SCR activity of Pt/SBA-15 is associated with its outstanding oxidation activities of NO to NO 2 and C 3 H 6 to CO 2 in low temperature range.The research results also suggested that higher concentration of O 2 and higher concentration of C 3 H 6 favored NO removal.The incorporation of Al into SBA-15 improved catalytic performance,which could be ascribed to the enhancement of catalyst surface acidity caused by tetrahedrally coordinated AlO 4.Moreover,the catalysts could be easily reused and possessed good stability.     

Removal of nitric oxide from simulated flue gas via denitrification in a hollow-fiber membrane bioreactor

A hollow-fiber membrane bioreactor(HMBR) was studied for its ability to treat nitric oxide(NO) from simulated flue gas. The HMBR was operated for 9 months and showed a maximum elimination capacity of 702 mg NO/(m2·day) with a removal efciency of 86%(gas residence time of 30 sec, inlet NO concentration of 2680 mg/m3, pH 8). Varying operation parameters were tested to determine the stability and response of the HMBR. Both the inlet NO concentration and gas residence time influenced the removal of NO in the HMBR. NO elimination capacity increased with an increase in inlet NO concentration or a shortening of gas residence time. Higher removal efciency of NO was obtained at a longer gas residence time or a lower inlet NO concentration. Microbial communities of the HMBR were sensitive to the variation in pH value and alkalescence corresponding to an optimum pH value of 8. In addition, NO elimination capacity and removal efciency were inversely proportional to the inlet oxygen concentration. Sulfur dioxide had no great influence on elimination capacity and removal efciency of NO. Product analysis was performed to study N2O and N2 production and confirmed that the majority of the microorganisms were denitrifying bacteria in the HMBR. Compared to other bioreactors treating NO, this study showed that the denitrifying HMBR was a good option for the removal of NO.     

疏水型H-ZSM-5分子筛上NO氧化反应的研究

针对NO低温氧化催化剂的抗水汽性差的问题,以疏水型高硅H-ZSM-5分子筛为NO氧化催化剂,在温度为10~90℃、NO进口浓度为0.05%~0.08%,及相对湿度为0~100%条件下,考察了NO的氧化反应.结果表明,H-ZSM-5分子筛的硅铝比由50提高至300时,湿气条件(水汽含量1.18%)下,NO氧化率由20%升高至56%;干气下,低温有利于NO氧化;湿气下(水汽含量1.18%),NO氧化率随着温度的升高先增加后减少,最佳反应温度为20℃,与NOx工业废气的排放温度相近.200h的稳定性试验结果显示,在30℃、NO进口浓度0.08%、空时0.5s、保持相对湿度为50%或100%时,NO氧化率可维持在60%和50%,催化剂具有良好的稳定性.     

Regeneration performance and carbon consumption of semi-coke and activated coke for SO2 and NO removal

To decrease the operating cost of flue gas purification technologies based on carbon-based materials, the adsorption and regeneration performance of low-price semi-coke and activated coke were compared for SO₂ and NO removal in a simulated flue gas. The functional groups of the two adsorbents before and after regeneration were characterized by a Fourier transform infrared (FTIR) spectrometer, and were quantitatively assessed using temperature programmed desorption (TPD) coupled with FTIR and acid–base titration. The results show that semi-coke had higher adsorption capacity (16.2% for SO₂ and 38.6% for NO) than activated coke because of its higher content of basic functional groups and lactones. After regeneration, the adsorption performance of semi-coke decreased because the number of active functional groups decreased and the micropores increased. Semi-coke had better regeneration performance than activated coke. Semi-coke had a larger SO₂ recovery of 7.2% and smaller carbon consumption of 12% compared to activated coke. The semi-coke carbon-based adsorbent could be regenerated at lower temperatures to depress the carbon consumption, because the SO₂ recovery was only reduced a small amount.     

不同光源下TiO2/ACF同时脱硫脱硝实验研究

实验室制备了负载型二氧化钛光催化剂TiO₂/ACF,利用自行设计的光催化反应器,在紫外和可见2种光源下进行了同时脱硫脱硝试验,确定了最佳的试验条件,比较了2种不同光源下的脱除效率.结果表明,烟气中氧含量、反应温度、烟气含湿量、光照强度等是影响光催化的主要因素,在紫外光源的照射下,负载型TiO₂/ACF光催化剂脱除SO₂和NO的效率分别达到99.7%和64.3%,在可见光源的照射下,负载型TiO₂/ACF光催化剂脱除SO₂和NO的效率分别达到97.5%和49.6%, 5次平行试验结果表明,平行数据的标准偏差S较小.通过反应后吸收液的离子色谱分析,推测了2种不同光源下同时脱硫脱硝的反应机制.