复合氧化物用于汽车排气催化氧化的实验研究

本文制备出一种非贵金属复合氧化物催化剂 ,可用于治理汽车排气中的 CO和 HC,初步研究了其对 CO和 C3 H6的催化氧化效果 ,实验结果表明 ,该催化剂具有较好的催化氧化能力     

Selective catalytic reduction of NOx from exhaust of lean-burn engine over Ag-Al2O3/cordierite catalyst

A highly effective Ag-Al₂O₃ catalyst was prepared using the in-situ sol-gel method, and characterized by surface area using nitrogen adsorption, scanning electron microscopy (SEM), and transmission electron microscopy (TEM) techniques. The catalyst performance was tested on a real lean-burn gasoline engine. Only unburned hydrocarbons and carbon monoxide in the exhaust were directly used as reductant (without any external reductant), the maximum NO _x conversion could only reach 40% at 450°C. When an external reductant, ethanol was added, the average NO _x conversion was greater than 60%. At exhaust gas temperature range of 350–500°C, the maximum NO _x conversion reached about 90%. CO and HC could be efficiently oxidized with Pt-Al₂O₃ oxidation catalyst placed at the end of SCR converter. However, NO _x conversion drastically decreased because of the oxidation of some intermediates to NO _x again. The possible reaction mechanism was proposed as two typical processes, nitration, and reduction in HC-SCR over Ag-Al₂O₃.     

车用乙醇汽油和无铅汽油对电喷汽车排放性能的影响

分别对电喷车长时间燃用乙醇汽油、无铅汽油前后的喷油器流量进行了测试,并采用轻型汽车整车排放测试系统对燃用不同油时的主要污染排放物HC、CO和NO_x进行了分析.结果表明:与无铅汽油相比,乙醇汽油能有效降低发动机排放的CO和HC(均约10%)及经过三元催化转化器作用后HC、CO和NO_x的排放,燃用无铅汽油时整车在装有三元催化转化器下的排放达到或接近欧洲1号排放标准,换用乙醇汽油后,CO降低较明显,达30%左右,HC和NO_x分别降低约18%、10%,此时排放在欧洲1号排放标准之上或接近欧洲2号排放标准;乙醇汽油还具有优于无铅汽油的其它性能,如对喷油器有轻微的清净作用,发动机排放的CO和HC恶化趋势较慢,延长三元催化转化器的使用寿命.     

上海花园饭店污水处理装置的改进

1 概况 上海花园饭店,污水处理装置的全套设备从日本进口,占地面积约636m~2,采用接触曝气法处理污水。整套设施的主要技术指标包括:纳污量:800m~3/d;进水BOD≤250mg/L;进水SS≤250mg/L;出水BOD≤20mg/L;出水中大肠菌≤3000个/;制作泥饼307kg/d。     

Deactivation of Cu-SAPO-34 by urea-related deposits at low temperatures and the regeneration

Selective catalytic reduction(SCR) with urea catalyzed by Cu-SAPO-34 is an effective method to eliminate NO_x from diesel exhaust. However, urea-related deposits may form during cold-start and urban driving due to low exhaust temperatures. The activity of CuSAPO-34 at 175°C is significantly degraded by urea exposure, and 300°C is required for regeneration. Through in-situ diffuse reflectance infrared Fourier transform spectroscopy(DRIFTS) and temperature-programmed hydrolysis studies, the dominant stable deposit at 175°C is identified as biuret, which can be eliminated at 300°C. The urea-derived deactivation and regeneration mechanisms of Cu-SAPO-34 were compared with those of anatase-supported catalysts.     

Preparation of MnO2 decorated Co3Fe1Ox powder/monolithic catalyst with improved catalytic activity for toluene oxidation

In this paper, KMnO₄ was used to pre-treat Co₃Fe-layered double hydroxides (LDH) precursor to prepare MnO₂ decorated Co₃Fe₁O_x catalyst. The toluene oxidation performance of the catalyst was investigated systematically. The optimized 0.1MnCF-LDO catalyst exhibited the best catalytic performance, and the temperatures of 50% and 90% toluene conversion (T₅₀ and T₉₀) were 218 and 243°C, respectively. The apparent activation energy (E_a) was 31.6 kJ/mol. The characterization results showed that the pre-redox reaction by KMnO₄ could increase the specific surface area, Co³⁺ species amount and oxygen defect concentration of the catalyst, which are the main reason of the improved toluene catalytic activity. Besides, this method was also applied to enhance toluene oxidation of iron mesh based monolithic catalyst. The 0.1MnCF-LDO/Iron mesh (IM) catalyst showed a 90% toluene conversion at around 316°C which was much lower than that of without MnO₂ addition (359°C). In addition, the water resistant of all the catalysts was studied as well, all the samples showed relatively good water resistance. The toluene conversion still remained to be over >80% even in the presence of 10 vol.% water vapor.     

Iron-doped Mn-Ce/TiO2 catalyst for low temperature selective catalytic reduction of NO with NH3

The catalysts of iron-doped Mn-Ce/TiO 2(Fe-Mn-Ce/TiO 2) prepared by sol-gel method were investigated for low temperature selective catalytic reduction(SCR) of NO with NH 3.It was found that the NO conversion over Fe-Mn-Ce/TiO 2 was obviously improved after iron doping compared with that over Mn-Ce/TiO 2.Fe-Mn-Ce/TiO 2 with the molar ratio of Fe/Ti = 0.1 exhibited the highest activity.The results showed that 96.8% NO conversion was obtained over Fe(0.1)-Mn-Ce/TiO 2 at 180°C at a space velocity of 50,000 hr 1.Fe-Mn-Ce/TiO 2 exhibited much higher resistance to H 2 O and SO 2 than that of Mn-Ce/TiO 2.The properties of the catalysts were characterized using X-ray diffraction(XRD),N 2 adsorption,temperature programmed desorption(NH 3-TPD and NOx-TPD),and Xray photoelectron spectroscopy(XPS) techniques.BET,NH3-TPD and NOx-TPD results showed that the specific surface area and NH3 and NOx adsorption capacity of the catalysts increased with iron doping.It was known from XPS analysis that iron valence state on the surface of the catalysts were in Fe3+ state.The doping of iron enhanced the dispersion and oxidation state of Mn and Ce on the surface of the catalysts.The oxygen concentrations on the surface of the catalysts were found to increase after iron doping.Fe-Mn-Ce/TiO2 represented a promising catalyst for low temperature SCR of NO with NH3 in the presence of H2 O and SO2.     

南方-125摩托车消声器的改制

改制了南方 - 12 5摩托车消声器结构 ,建设了 5个空腔吸着段 ,建筑 4个空腔催化净化尾气段。通过试车结果得出 :消音器效果良好 ,最好在 5 0km h为 82dB(A) ,而尾气催化净化最好效果为HC全部催化为水蒸汽 ,而CO转化掉2 2 2 18% ,CO2 转换掉 2 4 72 7% ,空气含量也明显增加。此消音器改制简单易懂 ,有利于环境方面的要求 ,如果将此消音器加以推广 ,可有很高的经济价值     

铜锰基整体式催化剂对烧结烟气CO净化特性

基于改性铜锰氧化物作为CO催化活性组分,分别制备了催化剂原粉、以泡沫金属、堇青石为载体的两种整体式催化剂,在实验室配气条件下对比了3种样品的CO催化效率及稳定性,优选了堇青石整体式催化剂,并在某钢厂实际烧结烟气条件下测试了其在不同催化剂负载量、空速、温度下的CO催化效率、稳定性以及衰减后样品催化特性;最后批量制备了2m³优选整体式催化剂并开展了6000m³/h烧结烟气CO净化中试实验.结果表明,烟气高浓水蒸气显著抑制CO催化反应,经240h催化后T₉₀最大提升38℃;催化剂负载量越高,T₉₀越低,催化效率衰减时间越短,稳定后的效率越高,但随着空速增加,该优势减小;1440h(2个月)中试实验中,进气温度185~195℃下,CO催化效率大于85%(平均90%),出口CO浓度低于1000×10^-6,出口平均烟温达220℃,具有节能减排双重效益.     

Synergistic effects of Cu species and acidity of Cu-ZSM-5 on catalytic performance for selective catalytic oxidation of n-butylamine

In this work, a series of Cu-ZSM-5 catalysts with different SiO₂/Al₂O₃ ratios (25, 50, 100 and 200) were synthesized and investigated in n-butylamine catalytic degradation. The n-butylamine can be completely catalytic degradation at 350°C over all Cu-ZSM-5 catalysts. Moreover, Cu-ZSM-5 (25) exhibited the highest selectivity to N₂, exceeding 90% at 350°C. These samples were investigated in detail by several characterizations to illuminate the dependence of the catalytic performance on redox properties, Cu species, and acidity. The characterization results proved that the redox properties and chemisorption oxygen primarily affect n-butylamine conversion. N₂ selectivity was impacted by the Brønsted acidity and the isolated Cu²⁺ species. Meanwhile, the surface acid sites over Cu-ZSM-5 catalysts could influence the formation of Cu species. Furthermore, in situ diffuse reflectance infrared Fourier transform spectra was adopted to explore the reaction mechanism. The Cu-ZSM-5 catalysts are the most prospective catalysts for nitrogen-containing volatile organic compounds removal, and the results in this study could provide new insights into catalysts design for VOC catalytic oxidation.     

一种富稀土型三效催化剂的性能考察

对一种富烯土型三效催化剂的性能进行了考察，结果表明：该催化剂具有较好的三效活性和较好的启燃温度特性，具有较宛的空速适应范围，在空速为84000h^-1时，CO,NOx的转化率仍在90％以上，HC转化率仍在70％以上，该催化剂具有较好的耐老化性能，经实验室快速老化实验，即相当于实车行驶8万km,CO劣化系数，1.09,HC劣化系1．05，NOx劣化系数1．06，该催化剂经桑塔纳轿车整车28工况测试，其交化效果与该车配置的美国Engelherd公司的催化剂相当。     

Capture of carbon dioxide by amine-impregnated as-synthesized MCM-41

The novel carbon dioxide(CO2) adsorbents with a high capture effciency were prepared through impregnating the as-synthesized MCM-41 with three kinds of amines,namely diethylenetriamine(DETA) ,triethylenetetramine(TETA) and 2-amino-2-methyl-1-propanol(AMP) .The resultant samples were characterized by small angle X-ray diffraction and low temperature N2 adsorption.The synthesis way not only saves the energy or extractor to remove the template but also is environmentally friendly due to the absence of the potential pollutants such as toluene.CO2 capture was investigated in a dynamic packed column.The sample impregnated by TETA showed the highest adsorption capacity,approximately 2.22 mmol/g at 60°C due to its highest amino-groups content among the three amines.The CO2 adsorption behavior was also investigated with the deactivation model,which showed an excellent prediction for the breakthrough curves.     

纳米TiO_2-Al_2O_3负载CuMnO_x对甲苯的催化燃烧

研究采用改进的溶胶-凝胶法制备了TiO2-Al2O3复合载体,并用浸渍法制备CuMnOX/TiO2-Al2O3催化剂,通过对甲苯废气催化燃烧的实验,分别考察了Cu-Mn负载量、Cu/Mn摩尔比、焙烧温度及载体对催化剂制备过程及催化剂活性的影响。实验结果表明:活性组分负载量25%,铜锰活性组分的配比Cu:Mn=1:2,焙烧温度500℃是浸渍法制备CuMnOX/TiO2-Al2O3催化剂较佳的工艺条件;XRD衍射图谱表明,500℃下铜锰尖晶石的存在是催化剂催化活性优良的主要原因;由复合载体制备的CuMnOX/TiO2-Al2O3催化剂比单一载体制备的CuMnOX/Al2O3催化剂具有更高的甲苯转化率,其T99比单一载体要低20℃以上。     

Al2O3为载体的催化剂净化贫燃汽车尾气研究

在富氧条件下,考察了C₃H₆和C₂H₅OH在Ag/Al₂O₃、In/Al₂O₃、Sn/Al₂O₃、Co/Al₂O₃、Pt/Al₂O₃和Ag/Al₂O₃+Pt/Al₂O₃组合催化剂上选择性还原NO的性能.结果表明,Ag/Al₂O₃具有最高的NO还原活性.在负载型过渡金属氧化物催化剂上,会生成显著量的CO,其HC和CO氧化转化温度也远远高于Pt/Al₂O₃催化剂.串联组合Ag/Al₂O₃+Pt/Al₂O₃催化剂可显著拓宽活性温度范围,促进HC和CO氧化,降低N₂O和CH₃CHO生成量.     

Activity and hydrothermal stability of CeO2–ZrO2–WO3 for the selective catalytic reduction of NOx with NH3

A series of CeO_2–ZrO_2–WO_3(CZW)catalysts prepared by a hydrothermal synthesis method showed excellent catalytic activity for selective catalytic reduction(SCR)of NO with NH_3 over a wide temperature of 150–550°C.The effect of hydrothermal treatment of CZW catalysts on SCR activity was investigated in the presence of 10% H_2O.The fresh catalyst showed above 90% NO_x conversion at 201–459°C,which is applicable to diesel exhaust NO_x purification(200–440°C).The SCR activity results indicated that hydrothermal aging decreased the SCR activity of CZW at low temperatures(below 300°C),while the activity was notably enhanced at high temperature(above 450°C).The aged CZW catalyst(hydrothermal aging at 700°C for 8 hr)showed almost 80% NO_x conversion at 229–550°C,while the V_2O_5–WO_3/TiO_2 catalyst presented above 80% NO_x conversion at 308–370°C.The effect of structural changes,acidity,and redox properties of CZW on the SCR activity was investigated.The results indicated that the excellent hydrothermal stability of CZW was mainly due to the CeO_2–ZrO_2 solid solution,amorphous WO_3 phase and optimal acidity.In addition,the formation of WO_3 clusters increased in size as the hydrothermal aging temperature increased,resulting in the collapse of structure,which could further affect the acidity and redox properties.     

δ-MnO2 decorated layered double oxides in-situ grown on nickel foam towards electrothermal catalysis of n-heptane

Energy-saving and efficient monolithic catalysts are hotspots of catalytic purification of industrial gaseous pollutants. Here, we have developed an electrothermal catalytic mode, in which the ignition temperature required for the reaction is provided by Joule heat generated when the current flows through the catalyst. In this paper, Mn/NiAl/NF, Mn/NiFe/NF and Mn/NF metal-based monolithic catalysts were prepared using nickel foam (NF) as the carrier for thermal and electrothermal catalysis of n-heptane. The results indicated that Mn-based monolithic catalysts exhibit high activity in thermal and electrothermal catalysis. Mn/NiFe/NF achieve conversion of n-heptane more than 99% in electrothermal catalysis under a direct-current (DC) power of 6 W, and energy-saving is 54% compared with thermal catalysis. In addition, the results indicated that the introduction of NiAl (or NiFe) greatly enhanced the catalytic activity of Mn/NF, which attributed to the higher specific surface area, Mn³⁺/Mn⁴⁺, Ni³⁺/Ni²⁺, adsorbed oxygen species (O_ads)/lattice oxygen species (O_latt), redox performance of the catalyst. Electrothermal catalytic activity was significantly higher than thermal catalytic activity before complete conversion, which may be related to electronic effects. Besides, Mn/NiFe/NF has good cyclic and long-term stability in electrothermal catalysis. This paper provided a theoretical basis for applying electrothermal catalysis in the field of VOCs elimination.     

镍基催化剂的制备及其对垃圾气化产氢的催化活性

以陶粒为载体,采用常温浸渍法制备了负载型镍基催化剂,并利用X射线衍射分析(XRD)、X射线荧光分析(XRF)、BET、环境扫描电镜-能谱仪分析(ESEM-EDX)和元素分析等对其进行了表征,该催化剂BET表面积为101.3m2/g.活性组分NiO颗粒平均粒径约为2μm,均匀分散在载体表面.并在下吸式固定床气化炉中,进行水蒸气催化气化城市生活垃圾有机组分的实验来评价镍基催化剂的催化活性.结果表明,在镍基催化剂的作用下,H2和CO含量明显增加,H2含量最高达43.22%,CO2、CH4、C2H4和C2H6.平均含量降至1%以下.催化气化过程的产氢率远远高于气化过程,最高达19.9mol H2/kg,低温段催化气化的潜在产氢率高于气化过程,但高温段低于气化过程;高温有利于气化产气中H2和CO的生成,还可以促进CH4、C2H4和C2H6的分解.催化气化过程的焦油产率、灰渣产率明显低于气化过程,特别是焦油产率降至2%以下,而产气率则高于气化过程.     

Au/SnO_2/TiO_2催化氧化CO性能的研究

通过煅烧制备TiO2,用浸渍法负载SnO2,沉积沉淀法负载Au,制备不同SnO2含量的Au/SnO2/TiO2催化剂。采用BET、SEM、XRD等手段对催化剂样品进行表征并考察煅烧温度、SnO2的添加量等对Au/SnO2/TiO2催化剂催化CO氧化活性的影响。结果表明:Au/SnO2/TiO2催化活性比Au/TiO2明显提高;海绵钛在400℃煅烧后负载10%SnO2和1%的Au催化活性较好,在124℃左右能使气体中含量为2.94%的CO基本完全转化。     

Enhanced catalytic complete oxidation of 1,2-dichloroethane over mesoporous transition metal-doped γ-Al2O3

High-surface-area mesoprous powders of γ-Al₂O₃ doped with Cu^2 +, Cr^3 +, and V^3 + ions were prepared via a modified sol–gel method and were investigated as catalysts for the oxidation of chlorinated organic compounds. The composites retained high surface areas and pore volumes comparable with those of undoped γ-Al₂O₃ and the presence of the transition metal ions enhanced their surface acidic properties. The catalytic activity of the prepared catalysts in the oxidation of 1,2-dichloroethane (DCE) was studied in the temperature range of 250–400°C. The catalytic activity and product selectivity were strongly dependent on the presence and the type of dopant ion. While Cu^2 +- and Cr^3 +-containing catalysts showed 100% conversion at 300°C and 350°C, V^3 +-containing catalyst showed considerably lower conversion. Furthermore, while the major products of the reactions over γ-alumina were vinyl chloride (C₂H₃Cl) and hydrogen chloride (HCl) at all temperatures, Cu- and Cr-doped catalysts showed significantly stronger capability for deep oxidation to CO₂.     

NH3-SCR performance and the resistance to SO2 for Nb doped vanadium based catalyst at low temperatures

Niobium oxide as the promoter was doped in the V/WTi catalyst for the selective catalytic reduction(SCR)of NO.The results showed that the addition of Nb_2O_5could improve the SCR activity at low temperatures and the 6 wt.%additive was an appropriate dosage.The enhanced reaction activity of adsorbed ammonia species and the improved dispersion of vanadium oxide might be the reasons for the elevation of SCR activity at low temperatures.The resistances to SO_2of 3V6Nb/WTi catalyst at different temperatures were investigated.FTIR spectrum and TG-FTIR result indicated that the deposition of ammonium sulfate species was the main deactivation reason at low temperatures,which still exhibited the reactivity with NO above 200°C on the catalyst surface.There was a synergistic effect among NH_3,H_2O and SO_2that NH_3and H_2O both accelerated the catalyst deactivation in the presence of SO_2at 175°C.The thermal treatment at 400°C could regenerate the deactivated catalyst and get SCR activity recovered.The particle and monolith catalysts both kept stable NO_xconversion at 225°C with high concentration of H_2O and SO_2during the long time tests.