离子溶液修饰SAPO-34分子筛膜及其H2/CO2分离性能研究

采用离子溶液修复法来对传统二次生长法制备的分子筛膜进行修饰,制备出了缺陷较少、气体分离选择性能优越的分子筛膜。以四乙基氢氧化铵为模板剂,在220℃下水热晶化24h得到SAPO-34分子筛晶种。利用二次生长法在氧化铝载体表面水热合成了SAPO-34分子筛膜,并通过离子溶液浸渍,对分子筛膜缺陷进行修饰。通过X射线衍射及扫描电子显微镜对分子筛进行表征分析。通过气体分离装置对SAPO-34分子筛膜进行气体分离性能研究。结果表明:在298K,0.1MPa下分子筛膜对H_2/CO_2的分离因子从5.27提高到了6.76。     

模板法制备中孔炭及其负载氧化铈的SCR脱硝性能研究

以硅铝比为38的分子筛为模板,蔗糖为前驱体,用模板法制备了中孔炭材料,并对制备的材料进行了表征。重点探讨了以制备的碳材料为载体,Ce为活性组分的催化剂的脱硝性能。结果表明,制备出的碳材料存在部分中孔,平均孔径为2.9nm;负载了Ce的催化剂,NH3选择性催化还原(Selective catalytic reduction,SCR)脱硝性能比未负载的脱硝性能好,表明Ce具有催化作用;将制备的碳材料经硝酸预处理,发现Ce负载量为10%的催化剂脱硝活性最好,在380～450℃之间保持60%以上的NO转化率。     

咪唑/镍(Ⅱ)改性SAPO-34的制备及其催化CO_2加氢制备乙烯

按异丙醇铝:磷酸:硅溶胶:四乙基氢氧化铵:水:改性剂=1.0:0.8:0.6:2.0:52:0.01的质量比,先将异丙醇铝和磷酸溶于水,再加入硅溶胶和四乙基氢氧化铵的混合液,30℃搅拌4 h后加入摩尔比为1:1的咪唑和硝酸镍,60℃搅拌8 h,室温陈化24 h,在不锈钢水热合成反应釜中200℃晶化24 h,固体在120℃干燥12 h,550℃焙烧6 h,制得咪唑/镍(Ⅱ)改性SAPO-34分子筛。用X射线粉末衍射(XRD)、扫描电镜(SEM)、能量色散X射线(EDS)和N2吸脱附对咪唑/镍(Ⅱ)改性SAPO-34进行了表征。将改性后的SAPO-34分子筛与CuO-ZnO-Al_2O_3按质量比1:1机械混合制备了复合催化剂。在固定床微分反应器上测定了复合催化剂对CO2加氢制备低碳烯烃的催化性能。在温度400℃,压强3.0 MPa,碳氢体积比为1:3,空速为1800 m L/(gcat·h),复合催化剂用量为1.0 g时,二氧化碳的转化率达到73.8%,乙烯的选择性为67.7%,显示了较高的催化活性,并且当温度继续升高至450℃时,乙烯的选择性并未下降,显示了一定的耐高温性能。     

Sn掺杂MCM-41介孔分子筛的制备、表征及催化性能研究

在低模板剂浓度和弱碱介质中合成催化材料Si-MCM-41、Sn-MCM-41,并用XRD、N2物理吸附-脱附、FT-IR、ICP-AES和TEM等手段对催化材料进行了表征.研究了合成方法对制备Sn掺杂MCM-41介孔分子筛的影响,结果表明:水热晶化法(DHT)合成的Sn-MCM-41,Sn物种主要进入分子筛的骨架中;而模板离子交换法(TIE)合成的Sn-MCM-41,Sn物种主要位于分子筛的表面.Sn-MCM-41介孔分子筛催化环己酮Baeyer-Villiger氧化反应结果表明,n(H2O2):n(酮)=3:1,30g1,4-二氧六环为溶剂,H2O2为氧源,70℃反应6h,环己酮的转化率可达40.02%,ε-己内酯的选择性为45.69%.     

SAPO-17分子筛的合成、表征及催化性能研究

采用水热合成法成功合成出SAPO-17分子筛,并用XRD、SEM、N2吸附脱附、FT-IR、DTA/TG和NH3-TPD等方法研究了样品的物化性能。结果表明:合成的SAPO-17分子筛呈针状结构,并且具有较好的热稳定性。经过BET算法得到的比表面为406.71m2/g,孔径为0.65nm。合成不同硅铝比(Si/Al=0.05、0.08、0.11)的SAPO-17分子筛,均具有较好的MTO催化性能,其中硅铝比为0.11的SAPO-17分子筛催化性能最好,甲醇的转化率为100%,乙烯、丙烯收率分别为59.51%、26.35%。     

Cu含量对Cu/ZSM-5催化剂氨选择性催化还原NO影响的研究

采用浸渍法将铜(Cu)负载在ZSM-5分子筛上,制备了一系列不同Cu含量的Cu/ZSM-5分子筛催化剂。对ZSM-5及Cu/ZSM-5分子筛催化剂的氨选择性催化还原一氧化氮(NO)性能进行评价,并对Cu/ZSM-5分子筛催化剂进行表征分析。结果表明,Cu含量变化对Cu/ZSM-5分子筛催化剂的氨选择性催化还原反应(NH3-SCR)活性影响较大,Cu含量为0.75%(wt,质量分数)制得的Cu/ZSM-5具有最佳的中低温活性,在190℃条件下对NO的转化率为91%。     

不同硅铝比对Fe-Beta分子筛选择性催化还原性能的影响

采用离子交换法制备Fe-Beta分子筛,重点研究不同硅铝比对Fe-Beta的低温性能影响。以NO、NH_3、H_2O、CO_2为反应物的小样催化性能评价显示,当硅铝比为30时,Fe-Beta分子筛催化剂展现出优异的催化活性。研究表明,自主制备的Fe-Beta可有效降低NOx排放,副产物生成量极低。采用X射线衍射、扫描电镜、氮气吸附、氨气程序升温脱附、固体紫外光谱等手段研究分子筛物相结构与分子筛催化剂活性之间关系。结果表明,当控制Beta硅铝比为30,Fe负载量为1.3%时,Fe-Beta具有适宜的比表面积、酸性位及优异的NH_3-SCR活性。UV-vis谱图显示,分子筛中存在不同的Fe物种,通过分峰计算发现,孤立的Fe~(3+)、低聚物、高聚物大颗粒3种同时存在,其中孤立的Fe~(3+)、低聚的Fe■O_y为Fe-beta的SCR活性位点。高性能Fe-Beta催化剂的制备对指导满足非道路四阶段排放法规的高效环保SCR催化剂开发具有重要的理论及实践意义。     

三维有序介孔结构氧化钼制备及催化性能

以三维有序介孔分子筛KIT-6为模板剂制备碳模板, 七钼酸铵为钼源, 采用超声辅助下的真空浸渍法, 合成了三维(3D)有序介孔、蠕虫状介孔MoO₃。采用TEM、HRTEM、SAED、XRD、TG/DT、N₂吸脱附等对材料物理性能进行了表征。采用H₂-TPR、甲苯和一氧化碳完全氧化等对催化性能进行了评价。研究发现: 制备的三维有序介孔MoO₃为正交相晶体结构, 比表面积194 m²/g; 在转化率分别为50%、90%、100%时, 甲苯的起燃温度分别为203℃、215℃、225℃; CO起燃温度分别为114℃、158℃、180℃。3D-MoO₃优良的催化性能与高比表面和三维有序介孔架构密切相关。     

新型催化材料——介孔氧化铝分子筛的合成、表征以及应用前景

与传统的γ-Al2O3相比,介孔氧化铝分子筛具有较大的比表面积和较窄的孔径分布,作为工业催化剂或催化剂载体,具有更为广阔的应用前景.本文重点介绍了介孔氧化铝分子筛的不同合成方法、结构表征方法和催化性能,分析了模板剂类型、凝胶pH值、洗涤方法、焙烧方式等制备条件对其结构的影响.并对其催化应用进行了评述和展望.     

多级孔SAPO-34催化剂合成与应用的研究进展

SAPO-34分子筛被广泛应用于催化甲醇制取烯烃(MTO),但单一微孔结构沸石在催化过程中极易失活。多级孔结构沸石结合了微孔沸石和介孔材料的优点,在不影响微孔沸石固有的催化活性和选择性的前提下,增强了分子扩散和传质能力,极大增加分子筛催化寿命。该文综述了近年来多级孔分子筛的合成策略与催化性能表征。第一部分简介了分子筛结构,并阐明了其催化性能与扩散的关系。第二部分对目前多级孔SAPO-34的不同合成方法进行了对比与总结。最后针对目前多级孔分子筛不同合成方法做出总结与展望。     

活化晶种调节SAPO-34的性质及其对甲醇制烯烃反应催化寿命的增强

无溶剂法合成沸石法在多个方面优于常规水热合成法, 近年来引起广泛关注, 但是采用该方法合成的微孔SAPO-34沸石催化剂的催化寿命较短, 无法满足甲醇制烯烃工业应用的要求。本研究中开发了一种改良的无溶剂法, 使用该法合成了具有优异甲醇制烯烃反应性能的SAPO-34催化剂。该法在合成体系中引入酸活化晶种, 通过调节沸石晶化动力学来调控催化剂的物理化学性质。采用不同技术对无溶剂法合成的系列SAPO-34催化剂的结构性质进行了分析表征。结果表明：与未引入晶种合成的父代样品相比, 添加晶种得到的子代SAPO-34样品具有更高的结晶度、比表面积及低的强酸中心密度, 对甲醇制烯烃反应的催化寿命可延长到480 min, 远远优于对应的父代样品(40 min)。这一结果证实了无溶剂合成中晶种的使用可有效调节沸石的性质, 可见该方法在提高沸石催化性能方面具有巨大潜力。     

CoMOR zeolite catalyst prepared by buffered ion exchange for effective decomposition of nitrous oxide

Co contained MOR zeolite catalysts with high Co loadings were successfully synthesized by buffered ion exchange at pH 8, and were tested for N(2)O catalytic decomposition. The high exchange level of synthesized CoMOR(x)-BIE catalysts probably benefits from the maximizing hydroxycomplexes Co(OH)(+) ion in the buffered solution, which is more preferred for the ion exchange with the zeolites. It has been found that the novel CoMOR(x)-BIE catalysts exhibit excellent catalytic activities, which is attributed to the large population of isolated Co(2+) ions on ion exchange positions. The most active CoMOR(130)-BIE catalyst shows high resistance to the inhibition of oxygen, NO and water vapor. Furthermore, stability tests indicate that the CoMOR(130)-BIE catalyst has no obvious deactivation under simulated emission conditions after reaction for more than 100 h. This extraordinary durability could be related to its high Co(2+) content and low Br?nsted acidity sites in the catalyst, which facilitate the stability of active isolated Co(2+) on ion exchange positions. Thus, the CoMOR(130)-BIE catalyst shows a great potential as a cost-effective catalyst for N(2)O elimination in future applications.     

Fe-PPy-TsOH/C用作质子交换膜燃料电池氧电极催化剂的研究

氧电极催化剂是制约质子交换膜燃料电池(PEMFCs)发展和应用的一个重要因素, 开发低价高效的非贵金属催化剂对PEMFCs来说已成为当务之急。本研究选择氮掺杂的碳载过渡金属(M-N/C)类催化剂为研究对象, 以铁盐作为金属前驱体, BP2000为碳源, 聚吡咯(PPy)为氮源, 对甲基苯磺酸(TsOH)为掺杂剂, 合成了非贵金属催化剂Fe-PPy-TsOH/C, 探究了不同的热处理温度及钴原子的掺杂对其氧还原催化性能的影响。研究结果表明: 800℃制备的Fe-PPy-TsOH/C催化剂因结晶度高、颗粒大小适中且分布均匀而具有最佳的氧还原催化性能; 一定量的钴原子取代可以改善Fe-PPy-TsOH/C的氧还原催化性能, 当钴的掺杂量为33.33%时(铁钴原子比为2︰1), 催化剂的性能达到最优。     

Nitrogen oxides removal by catalytic methods

 Nitrogen oxides are harmful compounds, dangerous to the natural environment. This review reports on progress in studies of catalytic processes to promote nitrogen oxide decomposition as well as catalytic NO reduction from mobile exhaust sources. The activities of catalysts receiving attention in the technical literature range from metallic ones to transition metal oxides supported on zeolites, metal oxides and magnesium fluoride. Also the current ideas on the mechanism of catalytic decomposition and reduction of nitrogen oxides are reviewed. Received: 11 February 1999 / Accepted: 1 June 1999     

1,2 -二氯乙烷在担载铈钛复合氧化物的蜂窝陶瓷催化净化——催化组分颗粒大小的影响

采用溶胶-凝胶法制备担载 TiO2 和 CeTiOx 复合氧化物涂层的堇青石蜂窝陶瓷整体式催化剂,并考察 1,2-二氯乙烷(DCE)在上述催化剂上的催化效果。结果表明:TiO2 和 CeTiOx 复合氧化物涂层材料对DCE 的催化燃烧均具有很好的催化活性, 前者在 400 ℃时,DCE 的转化率为 93.1%,后者已达 98.5%,可见,CeTiOx 可以更有效地催化燃烧处理 DCE。譬如,在 300 ℃时,在 CeTiOx 涂覆的催化剂上 DCE 的转化率为 85.6%。但随着催化剂处理温度的升高,CeTiOx 催化活性组分的颗粒变大,导致 CeTiOx 蜂窝陶瓷催化剂对于 DCE 的催化活性降低。     

Incorporation of mixed metals into SAPO-34 frameworks by the dry-gel conversion method using mixed templates: investigating catalysts characterisation and performance

The crystallisation of the MeAPSO-34 material was studied under dry-gel conversion conditions and using two and three templates. This study has been focused on the effect of the incorporation of a mixture of Ni and Mn into the SAPO-34 framework. The MeSAPO-34 samples were characterised by X-ray diffraction, energy-dispersive X-ray spectrometer, scanning electron microscope, temperature-programmed desorption and Brunner–Emmett–Teller. The influence of metal incorporation into the framework of SAPO-34 (MeAPSO-34) on methanol conversion was investigated in this study. The performances on methanol conversion for these catalysts were different according to the properties of metals incorporated into the SAPO-34 structure. The catalytic performance demonstrated high activity and light olefins selectivity for the prepared catalysts. Among the light olefin products, Mn and Ni incorporation is helpful for propylene generation, but samples with a mixture of Ni and Mn favour the ethylene production.     

Kinetic study of trichloroethylene combustion on exchanged zeolites catalysts

In this paper is presented a kinetic study of the catalytic combustion of trichloroethylene (TCE) over Y-zeolites exchanged with several cations. The catalysts, based on zeolite, were prepared by ion exchange and characterized by means of physico-chemical techniques and then tested under kinetic conditions. The kinetic results obtained were interpreted using kinetic models of power-law type and Eley-Rideal. The results obtained indicate that catalyst Y-Cr is more active than Y-Co catalyst. The greater activity of catalyst exchanged with Cr can be attributed to the higher acidity that presented these catalysts.     

Metal encapsulation in zeolite particles: A rational design of zeolite-supported catalyst with maximum site activity

Zeolite-supported metal catalysts have been proven effective in many important catalytic reactions, such as hydrogenation, Fisher-Tropsch synthesis, automobile exhaust catalysis, selective catalytic reduction and many others. Despite the successful preparation of the catalyst through widely adopted methods, including ion exchange and impregnation, the metal dispersion over the zeolite is lack of control with high randomness. This renders the so-called “catalytic performance” an overall contribution from the metal sites located inside the zeolite micropores and those located on the external surface. This is exceptionally true for small to medium pore zeolites with typical free apertures of 0.3–0.6 nm (such as LTA and MFI). A more rational design of zeolite-supported metal catalysts is by encapsulating the metal nanoparticles or clusters within zeolite pores prior to the zeolite formation. Encapsulation of metals in zeolite prevents them from sintering and sulphur poisoning by cage confinement and molecular exclusion (via well-defined pore size and shape), respectively. This paper gives a new perspective on using metal clusters and nanoparticles as catalysts and the design of an effective zeolite-supported catalytic system.     

Decolorization of KN-R catalyzed by Fe-containing Y and ZSM-5 zeolites

Decolorization of an anthraquinone dye, Reactive Brilliant Blue KN-R by hydrogen peroxide was examined using Fe-containing Y and ZSM-5 zeolites as heterogeneous catalysts. Catalysts were prepared by ion-exchange and coprecipitation methods, and calcined at different temperatures. The surface morphologies, crystalline phases, and chemical-state of the catalysts were characterized by scanning electron microscopy, X-ray diffraction and X-ray photoelectron spectroscopy. Influences of reaction conditions, such as dye concentration, catalyst dosage and solution pH, were evaluated and the relations between catalytic capacity and surface microstructures were discussed. The results showed that Fe-containing Y and ZSM-5 zeolites generally exhibited similar or better catalytic efficiency compared with homogeneous Fenton reagent, with Fe-containing ZSM-5 being more efficient. Synthesis method and calcination temperature affected catalytic efficiency and the stability of catalysts. Fe-containing ZSM-5, which was prepared by coprecipitation and calcined at 450 degrees C, displayed the greatest decolorization capacity. Under the conditions of initial pH 2.5, 30.0 mmol/L H(2)O(2) and 4.0 g/L catalyst, 250 mg/L KN-R could be decolorized over 90% within 20 min.     

Application of mixed oxide catalysts to the removal of lean NOx and N2O using transient-mode cyclic operations

The storage and reduction of NO and N2O in the presence of excess O2 have been investigated over two mixed oxide catalysts. The catalysts, which were prepared via coprecipitation of solutions of mixed metal nitrates, followed by calcination, were found to have plenty storage capacities for nitrogen oxides. The storage and reduction performances varied with the catalyst composition and the duration of cycle time: the AlCoPd (1/1/0.05) mixed oxide catalyst exhibited higher efficiency for NO, and an AlCoFe (1/1/2) mixed oxide catalyst exhibited higher efficiency for N2O. The adsorptions of NO and N2O onto the mixed oxide catalysts progressed without an oxidation step, and the adsorptivity of NO surpassed that of O2. The mixed oxides showed spinel structures with sizes of 10-100 nm, and with well-developed mesopores that were formed by the evaporation of H2O and CO2 from layered double hydroxide (LDH) precursors. The storage and reduction of lean NOx and N2O over the mixed oxide catalysts were carried out via cyclic operations in a transient mode at 300 degrees C and at space velocities of around 30,000 h(-1). The removal efficiency of the cyclic operations generally increased with reduced adsorption cycle time, and reached 90% for NOx and N2O with the respective catalysts.