V2O5/WO3/TiO2催化剂制备及其SCR性能研究

本文通过浸渍法制备了V2O5/TiO2系列筛选催化剂及V2O5/WO3/TiO2负载型催化剂,并在模拟评价装置上考察了上述催化剂在SCR反应巾的催化性能.结果表明,V2O5在涂材料中应该低于3wt.%;钒系催化剂对NOx的净化效率随反应温度的升高,先增加而后减小,存在一个适宜反应温度窗口;随反应温度升高, NH3泄漏量逐渐降低,在温度达到350°C之后,NH3泄漏世不再随温度的升高而变化;SCR反应温度较低时HC和CO浓度基本不变,但从450°C开始,HC浓度逐渐降低,而CO浓度则急剧升高;随NOx/NH3比例增加,NOx转化效率逐渐降低.     

负载型Fe-Ce催化剂低温SCR脱硝性能的研究

以氧化铝为载体,负载不同比例的金属组分Fe、Ce制作单组分及多组分的负载型催化剂。实验研究在不同反应温度、氧含量和空速比下,此类负载型催化剂的SCR脱硝性能。结果表明:由于稀土元素Ce的加入,多组分的8Fe-2Ce/Al_2O_3的催化脱硝效率明显高于单组分的8Fe/Al_2O_3,在240℃时可达94%,而且具有比单组分催化剂更好的抗硫性能。但Ce的加入并不是越多越好,Ce的过量加入反而会影响催化剂的催化脱硝效率。催化剂的制备方法与其催化脱硝效率有关,沉淀法制备的催化剂的催化脱硝效率高于浸渍法制备的催化剂,以450℃煅烧制备的催化剂的催化脱硝效率高于550℃煅烧的催化剂。脱硝实验条件影响催化剂的催化脱硝效率,3%氧含量下的催化脱硝效率高于无氧条件下的,低空速比时脱硝效果高于高空速比的。     

氧化物替代对钒钛SCR催化剂性能影响研究

采用浸渍法制备了La_2O_3、Ce_2O_3和Co_2O_3等金属氧化物部分替代V_2O_5的氧化物-MoO_3-TiO_2型催化剂,并进行了理化性能和催化活性表征。结果表明:替代型催化剂的比表面积与钒型催化剂差别不大。在NH_3-SCR反应中,镧型和铈型催化剂不仪低温活性较高而且NO_x净化率在500℃时才开始衰减,具有最宽的活性温度窗口;钴型催化剂虽然低温活性最好,但其NO_x净化率在400℃即开始衰减,导致其活性温度窗口较窄,但还是比钒型催化剂宽。此外,反应温度是影响HC和CO排放变化的主要因素,而催化剂种类对其影响较小。1×10~5 h~(-1)以下时,不同空速对NO_x净化率影响较小;而空速达到3×10~5 h~(-1)时,NO_x净化率显著下降。     

RuO2/TiO2复合光催化剂的制备及性能研究

采用溶胶-凝胶-浸渍法制备了RuO2/TiO2复合光催化剂, 以紫外灯为光源, 直接耐晒黑G溶液的光催化降解为模型反应, 研究了RuO2/TiO2的光催化性能. 结果表明 掺杂量ω(RuO2)为0.16%、煅烧温度500 ℃、催化剂投加量为5.00 g·L-1时, RuO2/TiO2复合光催化剂催化活性最高. 直接耐晒黑G降解反应遵从Langmuir-Hinshelwood动力学模型, 测得反应速率常数为4.94×10-3 mmol(L·min)-1和吸附常数14.2 L·mmol-1.     

Tm-SO2-4/TiO2的催化酯化性能及XRD和IR表征

制备了固体超强酸催化剂Tm-SO4^2-／TiO2,用于柠檬酸与正丁醇的酯化反应。考察焙烧温度对TmSO4^2-／TiO2催化酯化性能的影响及其在酯化反应中的稳定性,用XRD与IR研究其结构与性能的关系。结果表明,焙烧温度为600℃条件下制得的催化剂,其催化选择性达99．2％;锐钛矿TiO2(A)晶相的形成与完善是提高催化选择性的关键因素。催化剂Tm-SO4^2-／TiO2具有良好的稳定性,重复使用5次后反应的转化率仍高达93．1％;负载Tm能显著降低催化剂表面的积碳量,且有效抑制SO4^2-的流失。     

煅烧温度对Cu/HMOR催化剂结构及其催化二甲醚羰基化反应性能影响

采用离子交换法在不同煅烧温度下制备HMOR负载Cu(Cu/HMOR)催化剂,用于催化二甲醚(DME)羰基化合成乙酸甲酯(MA)反应. 活性测试结果表明430 oC煅烧制得Cu/HMOR具有较好催化活性,在210 oC、1.5 MPa、空速4883 h^-1下DME转化率为97.2%,MA选择性为97.9%. 对催化剂进行X射线衍射、N₂物理吸附、NH₃程序升温脱附、CO程序升温脱附及拉曼方法表征. 催化剂经一定的煅烧温度有利于Cu离子迁移及扩散和硝酸铜完全分解,从而使HMOR载体具有较多的酸性活性位、大比表面、适宜的微孔结构以及更多的CO吸附位.     

Pr掺杂TiO2光催化剂的制备及其对酸性品红降解反应的催化性能

以钛酸四丁酯为前躯物,采用溶胶-凝胶法制备了掺杂不同含量Pr的TiO2光催化剂,利用XRD,TG-DTA,AFM,UV-Vis,FTIR等手段对催化剂进行了表征。并通过酸性品红光催化降解实验对其光催化性能进行了评价,考查了实验条件,如催化剂用量,烧结温度,掺杂量等对催化剂催化活性的影响。Pr2O3的掺杂阻碍了TiO2晶相由锐钛矿型向金红石型的转变,使TiO2的粒径减小,比表面积增大,催化活性增强。当Pr掺杂量为0.8%,催化剂用量为0.03g,烧结温度为500℃时,酸性品红的降解率达到97%以上,酸性品红的降解反应为准一级反应。     

负载Cu的镁铝复合金属氧化物催化合成碳酸丙烯酯

通过浸渍法制备了负载Cu的镁铝水滑石类化合物Cu/HT,经过450℃焙烧得到负载Cu的镁铝复合金属氧化物Cu/LDO,利用X射线衍射(XRD)、红外光谱(FTIR)分析等技术对催化剂的结构进行了表征。研究了其对尿素与1,2-丙二醇合成碳酸丙烯酯的催化性能。考察了反应温度、反应时间、催化剂用量等工艺条件对反应性能的影响。结果表明,以水滑石为前躯体的负载Cu的镁铝复合金属氧化物cu/LDO对尿素与1,2-丙二醇合成碳酸丙烯酯具有比较好的催化活性。当反应温度为170℃、1,2-丙二醇与尿素的摩尔比为4:1、催化剂用量为原料总质量的1.0%、反应时间为3h时,碳酸丙烯酯的收率达到95.2%。     

Pd-Cu双金属催化剂上加氢反应的仲氢诱导超极化研究

本文通过多相催化-仲氢诱导超极化（HET-PHIP）核磁共振（NMR）技术研究了Pd-Cu/SiO₂双金属催化剂上丙炔选择性加氢反应.首先利用等体积浸渍法和连续浸渍法合成了一系列不同Pd/Cu比例和形貌的Pd-Cu/SiO₂双金属催化剂.通过ALTADENA（Adiabatic Longitudinal Transport After Dissociation Engenders Net Alignment）方法发现,催化剂的Pd/Cu比例和形貌均对PHIP的极化效率有较大影响.随着Pd-Cu双金属催化剂中Pd比例的增大,PHIP极化效率降低,同时反应活性增强.在同Pd/Cu比例下,相对于等体积浸渍法,连续浸渍法制备的层叠形貌催化剂具有较弱的极化效率以及较强的催化活性,这是由于催化剂表面暴露出的Pd数量增多,导致催化活性增强;同时单个Pd集簇表面积增大,使得氢原子移动范围扩大,从而造成极化效率降低.     

TiO2/5A光催化降解水中CN-的催化活性

采用溶胶-凝胶-浸渍法制备TiO2/5A型催化剂,以其对水样中CN-降解率的大小来评价催化剂的光催化活性,并与P25型纳米TiO2催化效果作比较,从而探讨5A型分子筛负载纳米TiO2的百分含量、催化剂加入量、水样的pH值及CN-初始浓度对TiO2/5A光催化降解水中CN-催化活性的影响.结果表明:5A型分子筛负载纳米TiO2的量为20％、加入量为1.5g/L、pH=10、CN-初始浓度为50mg/L,反应时间为3h时,降解率达88.64％,且优于P25型纳米TiO2的降解效果.     

TiO2光催化剂的光谱研究

采用sol-gel法制备了纳米TiO2光催化剂,运用FTIR,FT－Ranam,DSR等光谱技术对催化剂进行了表征,以光催化解油酸作为模型反应考察光催化活性。实验结果表明,催化剂的烧结温度对催化剂的晶相结构、半导体能带结构、光吸收性能及光催化活性均产生显著的影响,当烧结温度为400℃时,TiO2光催化剂具有最好的表观吸光度,最大的吸收带边,以及最佳的光催化活性。     

Low-temperature Catalytic Reduction of Nitrogen Monoxide with Carbon Monoxide on Copper Iron and Copper Cobalt Composite Oxides

通过共沉淀法, 在低温下制备了铜铁复合氧化物CuO/Fe2O3和铜钴复合氧化物CuO/Co3O4．利用GC微反应器评价了这些复合氧化物的催化活性和热稳定性,结果表明, CuO/Fe2O3和CuO/Co3O4的NO100%转化温度分别为80和90 ℃,该催化活性和热稳定性在较宽的温度和较长的时间范围内都能得以保持．此外,还系统研究了试剂的摩尔比率、NaOH的体积、陈化时间、煅烧温度和煅烧时间对该复合氧化物催化活性的影响．     

Reactive dye degradation by combined Fe(III)/TiO2 catalyst and ultrasonic irradiation: Effect of Fe(III) loading and calcination temperature

The development of Fe(III)/TiO(2) catalysts for sonocatalytic degradation of Reactive Blue 4 (RB4) dye in water was carried out using sol-gel method. Their surface morphology, phase transformation and surface characteristics were studied using SEM, XRD and surface analyzer, respectively. Phase transformation from amorphous to anatase occurred at 500°C and transformation of anatase to rutile phase occurred at 700°C. Complete rutile phase was formed at 900°C with corresponding increase in the particle size. Increasing in Fe(III) loading led to a reduction in the anatase phase and with the formation of weaker and broader of diffraction peaks. Surface morphology of the prepared catalyst was clearly observed with increasing calcination temperature. Surface area of the prepared catalyst decreased with increasing calcination temperature or increasing Fe(III) loading. The combination of 0.4 mol% of Fe(III)/TiO(2) with ultrasonic irradiation gave the highest sonocatalytic activity in the removal of RB4 from the aqueous solution. On the other hand, the presence of even small amount of rutile inhibited the catalytic activity of catalyst. 1.5 g/L was the optimum amount of catalyst that led to the highest sonocatalytic degradation of RB4 with an efficiency of 90%. Aeration significantly accelerated the reaction rate. Higher removal at 96% could be achieved with the combination of 0.4Fe(III)/TiO(2) and aeration under ultrasonic irradiation.     

Selective hydrogenation of furfural to furfuryl alcohol over catalysts prepared via sonochemistry

Copper-chromite oxide and TiO2-supported copper-chromite oxide catalysts are prepared by various methods. They are characterized with ICP, BET, XRD, XPS, SEM, and TEM, etc. Their catalytic performance for liquid phase hydrogenation of furfural to furfuryl alcohol is also valuated. The catalysts prepared by ultrasound exhibit good performance. Catalytic activity of TiO2-supported catalysts is higher than that of catalyst without TiO2, notwithstanding they are all prepared by ultrasound. It is worth stressing that after reduced the TiO2-supported catalysts, which are X-ray amorphous, display good performance at 140 degrees C, while the catalysts without TiO2 show no activity under the same condition. Obtained results indicate that the catalytic performance of catalysts depends upon the amount of reducible copper ions and the activity decay is related to the loss of metal elements on the surface of catalyst.     

过渡金属氧化物催化剂上NH3 分解Claus反应机理研究

运用浸渍法制备了七种过渡金属氧化物催化剂 .对于NH3 分解反应均可获得很高的NH3 转化率 ;对于NH3 分解Claus反应则可以获得较高的SO2 转化率和单质硫选择性 .通过比较发现Co3 O4 TiO2 和Fe2 O3 TiO2 催化剂的低温活性比较高 .经过XRD表征发现 ,在NH3 分解Claus反应中 ,催化剂的活性相可能是过渡金属硫化物 .结合活性评价和XRD表征结果提出了NH3 分解Claus反应的机理 .     

Effect of Preparation Method on the SCR Activity of Fe-Doped CoCr Oxide Catalysts

Fe-doped CoCr oxide catalysts are prepared by solid-phase mixing method, coprecipitation method, mechanical mixing method, and citric acid method, respectively, and their catalytic activity in the selective catalytic reduction of nitrogen oxides with NH₃ (NH₃-SCR) is tested. The Fe_0.5CoCrO_x catalysts prepared by all preparation methods have good water resistance and sulfur resistance when the calcination temperature is 400 °C. Fe_0.5CoCrO_x prepared by coprecipitation method by calcination at 400 °C (CP-400) is shown to have the optimum catalyst activity. In addition, the catalysts are characterized by a series of characterizations. The characterization results show that CP-400 has the largest specific surface area, which makes the active and acidic sites highly dispersed on the surface of CP-400, resulting in stronger redox and acidity and improved SCR activity. The removal of NO by NH₃-SCR over CP-400 at 150 °C follows the Eley-Rideal (E R) and Langmuir-Hinshelwood (L H) mechanisms.     

费-托合成制清洁燃料用担载纳米钴基催化剂制备中热处理对其结构和催化性能的影响

" 应用浸渍法在不同的焙烧条件(90~500 ℃)制备了一系列Al2O3担载钴基催化剂(质量含量为15%);采用XRD、XPS、程序升温还原对其进行了结构表征和分析,考察其在一氧化碳选择加氢制备清洁燃料用长链烷烃的反应中的催化性能．XPS结果表明,对于在90~200 ℃焙烧的催化剂,仍可观察到未完全分解的硝酸钴的存在;对于在200~500 ℃焙烧的几个催化剂可观察到Co3O4的物相．对于经过几种热处理制备的氧化铝担载的四个纳米钴基催化剂(200~500 ℃热处理),XRD和XPS结果表明四个样品中主要是9     

Mechanism for enhancing dispersion of Co3O4 nanoparticles in Co/SiO2 Fischer–Tropsch synthesis catalyst by adding glycol to impregnating solution: a quick‐XAFS study

In situ Co K‐edge quick‐EXAFS (QEXAFS) coupled with temperature‐programmed oxidation as well as ex situ XAFS was applied to investigating the mechanism for enhancing the dispersion of Co₃O₄ nanoparticles in a calcined Co/SiO₂ Fischer–Tropsch synthesis catalyst prepared by adding triethylene glycol (TEG) to a Co(NO₃)₂.6H₂O impregnating solution. Ex situ Co K‐edge XAFS indicated that, regardless of whether the catalysts were prepared with or without using TEG, the hexaaqua Co (II) complex was formed in impregnated samples which then underwent the dehydration process to some extent during the subsequent drying step at 393 K. In situ QEXAFS and ex situ EXAFS results also indicated that small oxide clusters were formed in the TEG‐modified catalyst calcined at ～400–470 K which interacted with polymer species derived from TEG. Since the Fischer–Tropsch synthesis activity of the TEG‐modified catalyst increased with an increase in the calcination temperature in a similar temperature range [Koizumi et al. (2011), Appl. Catal. A, 395 , 138–145], it was suggested that such an interaction enables the clusters to be distributed over the support surface uniformly, resulting in enhancing their dispersion. After combustion of polymer species, Co₃O₄‐like species were formed, and agglomeration of the Co₃O₄‐like species at high calcination temperatures was suppressed by the addition of TEG to the impregnating solution. It was speculated that the addition of TEG induced the formation of some surface silicate which worked as an anchoring site for Co₃O₄ and Co⁰ nanoparticles during calcination and H₂ reduction, respectively.     

Effect of Calcination Temperature on La-Modified Al2O3 Catalysts for Vapor Phase Hydrofluorination of Acetylene to Vinyl Fluoride

利用沉积沉淀法制备出了La改性Al₂O₃催化剂,研究不同焙烧温度对La改性Al₂O₃催化剂用于乙炔气相氢氟化合成氟乙烯反应性能的影响．利用NH₃-TPD、Pyridine-FTIR、XRD和Raman等技术对不同温度焙烧的催化剂进行表征,发现焙烧过程能改变催化剂结构的同时也能调变催化剂表面的酸量．经400 °C焙烧的催化剂显示出最高的乙炔转化率(94.6%)、最高的氟乙烯选择性(83.4%)和较低的积炭选择性(0.72%)．催化剂的高活性与其表面的高酸量有关,同时积炭的选择性也与其表面的酸中心数量有关．