Ti-MOR钛硅分子筛催化甲乙酮氨氧化反应性能

以TiCl4蒸气处理深度脱铝的丝光沸石,采用气固相同晶置换制备了含钛丝光沸石(Ti-MOR),并以H2O2作为氧化剂,考察了釜式反应器中Ti-MOR催化甲乙酮(MEK)与氨的液相氨氧化反应合成甲乙酮肟(MEKO)的性能,进而在连续淤浆床反应器中评价了Ti-MOR的稳定性和选择性.结果表明,在优化的反应条件下,Ti-MOR催化剂上MEK连续氨氧化反应的转化率和MEKO选择性分别达到95%和99%以上,优于传统的钛硅分子筛TS-1;同时,MEK转化率、MEKO选择性、催化剂耐积炭性以及稳定性等指标接近结构重排改性的Ti-MWW催化剂.     

钛硅分子筛TS-1合成晶化气氛的影响

考察了不同晶化气氛(N2、H2、A ir、O2)对合成钛硅分子筛TS-1的影响,用XRD、IR和N2吸附/脱附对所合成的钛硅分子筛进行结构表征,发现在H2气氛下合成的TS-1结晶度最高,锐钛矿的含量最少;O2气氛下合成的TS-1中锐钛矿含量最高.以氯丙烯氧化为模型反应,考察了不同晶化气氛下合成的钛硅分子筛的催化活性和双氧水的利用效率.结果表明,在H2气氛下所合成的钛硅分子筛的双氧水的利用效率最高.     

BEA/MOR两相共生分子筛的酸性及其催化性能

 用NH3-TPD方法研究了相同硅铝比不同相组成的BEA/MOR (β沸石与丝光沸石两相共生分子筛)样品的酸性,并考察了其对甲醇脱水制二甲醚反应的催化性能. 结果表明,不同相组成的共生分子筛样品的NH3-TPD谱中均出现两个NH3脱附峰,分别对应于NH3在沸石骨架中弱酸中心和强酸中心上的脱附. BEA/MOR的高温脱附峰温与其丝光沸石含量呈火山形曲线关系,而β沸石与丝光沸石机械混合物的高温脱附峰温与丝光沸石含量呈线性关系; 当丝光沸石相含量超过50%时, BEA/MOR强酸强度明显高于机械混合物,含丝光沸石65%的BEA/MOR样品的强酸强度最强,这表明共生分子筛与机械混合物间存在明显的区别. 用于催化甲醇脱水制二甲醚反应时, BEA/MOR样品上甲醇转化率与丝光沸石含量也呈火山形曲线关系,而机械混合物上甲醇的转化率与丝光沸石含量呈线性关系. 丝光沸石含量超过40%的BEA/MOR样品的催化活性都高于HM, 含丝光沸石65%的BEA/MOR样品活性最高. 硅铝比为11的HM虽然初活性高,但反应60 h后即很快失活,而硅铝比为53的HBEA/MOR初活性稍低,但其稳定性好.     

钛硅分子筛催化1-丁烯环氧化研究

自1983年Taramasso等报导TS-1的合成以来，钛硅分子筛的合成及应用一直是分子筛催化领域的热点。经典TS-1合成方法采用四丙基氢氧化铵（TPAOH）为模板剂，合成成本较高、条件苛刻，限制了其应用。用四丙基溴化铵（TPABr）为模板剂代替TPAOH，能够成功地合成TS-1。不同孔道结构的钛硅分子筛，如Ti-β、Ti-MCM-41、Ti-HMS等弥补了TS-1较小孔径的缺点，进一步扩大了钛硅分子筛的应用。本文以不同合成方法得到的TS-1及中孔Ti—HMS为催化剂，双氧水为氧化剂，1-丁烯环氧化合成1，2-环氧丁烷，研究了不同钛硅分子筛对1-丁烯环氧化反应的催化性能。     

用无机钛源合成Ti-MCM-41的研究

采用无机络合剂稳定钛酰离子的方法,用多种无机钛源合成出了中孔Ti-MCM-41型分子筛,采用XRD,低温N2吸附和FT-IR等方法对合成的含钛分子筛进行了物性的表征。以苯乙烯的H2O2氧化作为模型反应,考察了合成的Ti-MCM-41分子筛的催化性能。结果表明,钛原子已进入分子筛骨架,用Ti(SO4)2和TiCl4为钛源合成的Ti-MCM-41分子筛在960cm^-1处存在较强的红外吸收,并对苯乙烯的H2O2氧化表现出较高的催化活性。     

丙烯环氧化反应中失活钛硅分子筛的无氧脱附研究

采用无氧脱附方法对丙烯环氧化中失活的薄层钛硅分子筛(即Spent EPO-4)和环氧丙烷(PO)与丙二醇单甲醚(MME)浸渍的TS-1催化剂(即PO／TS-1和MME／TS-1)进行了研究，脱附产物由气相色谱定性分析，无氧脱附后的催化剂以丙烯环氧化为探针反应进行再生性能评价，同时在无氧条件下考察了TS-1在300℃时催化裂化PO反应．实验结果表明：PO浸渍TS-1可使其活性明显下降，PO在TS-1上不是简单的弱吸附，存在着化学强吸附和自聚．失活催化剂(Spent EPO-4和PO／TS-1)经无氧脱附后，其催化活性可显著恢复．通过对失活催化剂脱附产物的比较，推测了丙烯环氧化反应过程中钛硅分子筛失活原因．     

Ti-ZSM-5骨架钛的表征和催化活性的研究

采用TiCl4二次合成法,合成了不同肽含量的Ti-ZSM-5分子筛,用XRD,UV－Vis,XPS,IR等方法对分子筛进行了表征,XRD,XPS及UV－Vis证明分子筛所载的钛进入分子筛骨架,但IR却出现与文献报道不同的结果：钛硅分子筛的IR在960cm^-1上没有吸收峰;同时利用该分子筛催化苯乙烯氧化反应,发现其催化活性随分子筛载钛量的增加而增大。     

多级孔FAU型钛硅酸盐沸石的合成及其高效的氧化脱硫催化性能

通过硝酸脱铝和干法浸渍法成功地合成了具有多级孔结构的Ti-USY分子筛。脱铝过程可以将介孔引入沸石分子筛而不会破坏其骨架结构。通过X射线粉末衍射、傅里叶变换红外光谱、UV-Vis光谱、N2吸附-脱附等温线以及扫描/透射电子显微镜表征技术证实多级孔Ti-USY中具有骨架四配位的钛物种。与微孔TS-1分子筛相比,多级孔Ti-USY分子筛在二苯并噻吩(DBT)的氧化脱硫反应中显现出更加出色的催化性能,在60℃下1h内脱硫效果达到99.0%。结果表明,多级孔Ti-USY分子筛在深度氧化脱硫领域具有潜在的应用前景。     

液相酸溶液后补钛合成Ti-MWW分子筛

首先在含钠体系硼酸与哌啶用量较少的条件下水热合成B-MWW分子筛前驱体, 然后对其进行液相酸溶液后补钛, 合成了高结晶度的Ti-MWW分子筛. 利用粉末X射线衍射、 氮气吸附-脱附分析、 紫外-可见漫反射光谱和紫外拉曼光谱等技术考察了硅钛比、 温度等后补钛参数对所合成Ti-MWW分子筛的织构性质、 钛物种周围配位环境及催化1-己烯环氧化性能的影响, 确定适宜液相后补钛的硅钛比为30, 温度为373 K. 并且发现, 在后补钛体系中添加少量氟化铵可显著提高所合成Ti-MWW分子筛对1-己烯环氧化的催化活性. 本研究不仅证实了酸处理Ti-MWW分子筛前驱体的脱硼补钛机制, 也为Ti-MWW分子筛的合成提供了一种新的方法与思路.     

钛硅沸石合成中各组分作用研究

1983年Ｔａｒａｍａｓｓｏ等[1]报导了钛硅沸石ＴＳ-1的合成。由于在用稀Ｈ2Ｏ2为氧化剂的低温氧化反应中ＴＳ-1的突出催化性能,所以近年来钛硅沸石的合成、表征及催化应用研究一直是热点课题。经典的钛硅沸石合成需要采用昂贵的模板剂-不含碱金属离子的四丙基氢氧化铵(Ｔ...     

核壳结构碳化钨复合微球催化剂对甲醇电催化性能

以偏钨酸铵微球为前驱体,在不同反应时间和CO/CO₂气氛条件下,通过原位还原碳化反应制备了具有核壳结构碳化钨复合微球。采用X射线粉末衍射（XRD）、X射线光电子能谱（XPS）和扫描电镜（SEM）等对催化剂的形貌和结构进行了表征分析。硼氢化钠还原法将平均粒径为4.6 nm的Pt纳米粒子均匀分布在其表面,得到核壳结构碳化钨复合催化剂。采用循环伏安和计时电流法研究了在酸性溶液中催化剂对甲醇的电催化氧化性能。结果表明,与Pt/WC-15 h和JM Pt/C催化剂的电化学性能相比,Pt/WC-6 h催化剂对甲醇呈现出更高的电催化氧化活性和稳定性。碳化钨复合微球表面少量WO₂成分的存在有利于甲醇在其表面的电催化氧化过程的发生。     

Low energy ion bombardment of Ti and TiNx films

The influence of low energy ion bombardment on TiN_x film growth and film properties was investigated. The discharge was characterized using Langmuir probe technique as well as energy resolved mass spectrometry with a plasma monitor (Hiden HAL 301 S/EQP). The deposited films were investigated by means of X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Increasing the N₂ gas flow as well as increasing the negative substrate voltage at constant gas flow effect an increase of the N/Ti ratio in the films determined by XPS. The influence of the energy flux to the surface due to ion bombardment was mainly recognized in the substructure of the films. In addition, pure Ti films were modified by nitrogen ion bombardment after deposition using an ion gun. An increase of the N/Ti ratio was observed with increasing ion energy. Finally saturation is reached.     

胶原纤维为模版制备TiO2及La/TiO2纳米纤维及光催化活性研究

以胶原纤维为模版分别负载钛(Ti4+)或钛(Ti4+)和镧(La3+),在高温下煅烧制得TiO2和La/TiO2纳米纤维。通过扫描电镜(SEM)、场发射扫描电镜(FESEM)、X-射线衍射(XRD)、比表面积和孔径分析、X-射线光电子能谱(XPS)、紫外可见光谱(UV-Vis)等对这2种纳米纤维的结构和物理性能进行了表征。结果表明,TiO2和La/TiO2较完整地保持了胶原纤维的纤维状结构。在600~800℃范围内随着煅烧温度的升高,TiO2和La/TiO2的晶粒尺寸逐渐增大,晶格常数发生各相异性的变化。La/TiO2的相变温度在700~800℃之间,明显高于未掺杂TiO2的相变温度。N2吸附-脱附等温线按Langmiur分类为Ⅳ类,表明TiO2和La/TiO2纳米纤维具有介孔结构。与Degussa P25相比,TiO2和La/TiO2吸收光谱范围明显红移。当以可见光为光源进行酸性橙Ⅱ光助催化降解反应时,TiO2和La/TiO2纳米纤维均表现出比Degussa P25更高的催化活性。     

Synthesis, crystallization mechanism, and catalytic properties of titanium-rich TS-1 free of extraframework titanium species

A new route to the synthesis of TS-1 has been developed using (NH4)2CO3 as a crystallization-mediating agent. In this way, the framework Ti content can be significantly increased without forming extraframework Ti species. The prepared catalyst had a Si/Ti ratio as low as 34 in contrast to the ratio of 58 achieved with the methods A and B established by the Enichem group (Clerici, M. G.; Bellussi, G.; Romano, U. J. Catal. 1991, 129, 159) and Thangaraj and Sivasanker (Thangaraj, A.; Sivasanker, S. J. Chem. Soc., Chem. Commun. 1992, 123), respectively. The material contained less defect sites than the samples synthesized by the other two methods. As a result, it showed much higher activity for the oxidation of various organic substrates, such as linear alkanes/alkenes and alcohols, styrene, and benzene. The crystallization mechanism of TS-1 in the presence of (NH4)2CO3 was studied by following the whole crystallization process with X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), thermogravimetry/differential thermal analysis (TG/DTA), inductively coupled plasma atomic emission spectrometry (ICP), Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), diffuse reflectance UV-vis spectroscopy, and (29)Si MAS (magic-angle spinning) NMR spectroscopy techniques. It was shown that the presence of (NH4)2CO3 not only drastically lowered down pH, slowing down the crystallization process and making the incorporation of Ti into the framework match well with nucleation and crystal growth, but also modified the crystallization mechanism. It seems that the solid-phase transformation mechanism predominated in the crystallization process initiated by dissociation, reorganization, and recoalescence of the solidified gel although a small amount of nongelatinated Ti shifted to the solid during the crystal growth period. In contrast, a typical homogeneous nucleation mechanism occurred in the method A system. Thus, although in the method A system most of Ti cations was inserted into the lattice after the crystallization was nearly completed, the inclusion of Ti started at the earlier nucleation period in the presence of (NH4)2CO3. This is favorable for the incorporation of Ti into the framework, resulting in a more homogeneous distribution of Ti in the framework. Oxidation of 1-hexene and 2-hexanol over the samples collected during the whole crystallization process indicated that condensation of Ti-OH and Si-OH proceeded even after the crystallization was completed. This resulted in an increase in hydrophobicity and an overall improvement in microscopic character of Ti species and consequently a great increase in the catalytic activity with further progress of crystallization.     

Synthesis and morphological studies of nanocrystalline MOR type zeolite material

A number of nanosize mordenite (MOR) analogues with particle size ranging from 5 to 50 nm were synthesized by the hydrothermal method. The effect of various growth parameters like: alkalinity of the medium, type of silica source, etc. on crystal morphology and the crystal size of MOR type of zeolites was investigated. Specific surface and micropore volume were investigated by the Brunauer-Emmett-Teller (BET) method. XRD, SEM, TEM studies indicate nanosize growth of the MOR type crystals. Electron diffraction patterns confirm the crystalline nature of the nanoparticles and the results of their indexing prove that the material is MOR. These synthesized materials show microporous as well mesoporous character. In the case of MOR material synthesized using sodium silicate, it was found that an increase in the alkalinity of the medium led to changes in the morphology and crystal size of the material. For low concentrations of NaOH, the crystallites were spherical in shape whereas at high concentrations, they were in the shape of nanorods of diameter 25 to 50 nm. The morphology of the MOR material synthesized using tetraethyl orthosilicate (TEOS), on the other hand, did not change when the NaOH concentration was increased beyond 2.0 molar.     

溶胶-凝胶-水热晶化法制备锐钛矿TiO2纳米膜的耐蚀性能

以钛酸正丁酯为前驱体, 采用溶胶-凝胶-水热晶化法在不锈钢(SS)表面制备TiO₂纳米膜. 利用X射线衍射(XRD)、Raman光谱、场发射扫描电子显微镜(SEM)、原子力显微镜(AFM)和俄歇电子能谱(AES)表征了TiO₂纳米膜的晶型、表面形貌和表面化学组成. 通过极化曲线和电化学阻抗谱(EIS)研究了TiO₂纳米膜的耐蚀性能. 170 °C下水热晶化制备的锐钛矿TiO₂与450 °C焙烧制备的锐钛矿TiO₂的结晶度类似, 但两种TiO₂薄膜的表面结构存在明显差异, 水热晶化法制备的TiO₂纳米膜在3.5% (w) NaCl溶液中的耐蚀性能优于焙烧法制备的.     

纳米氧化锰负载钛基电催化膜制备及处理含酚废水性能研究

以多孔钛膜为基膜,醋酸锰为锰源,采用溶胶凝胶法制备出负载纳米氧化锰的钛基电催化膜（nano-MnO_x/Ti膜）. 运用X射线衍射(XRD)、 X射线光电子能谱(XPS)、场发射扫描电子显微镜(FESEM)、循环伏安法(CV)、交流阻抗法（EIS）和计时电流法(CA)等测试手段,对MnO_x/Ti膜电极的微观形貌、晶型、电化学性能等进行表征. 结果表明：所得催化剂是由直径为50 nm的γ-MnO₂和Mn₂O₃纳米棒所组成,且均匀分布于Ti膜上,负载催化剂后钛膜电极电化学性能和催化性能明显提高,催化剂与基体之间键合的形成提高其稳定性. 以棒状nano-MnO_x/Ti膜电极为阳极构建电催化膜反应器(ECMR)处理含酚废水,当苯酚溶液浓度为10mmol·L^-1,电流密度为0.25mA·cm^-2、停留时间为15 min时,COD去除率可达95.1%.     

含有乙醚的无胺无氟反应物体系中高硅丝光沸石的合成

本文研究含有乙醚的Na2O-Al2O3-SiO2-H2O反应物中高硅丝光沸石在413-453K下的水热合成。乙醚的存在能有效促进丝光沸石的结晶过程,且有助于提高产物结晶度和硅铝比。反应物胶体中硅铝比与碱度对产物的生成有关键作用。合成原料使用不同铝源,体系结晶规律相近,但产物的形貌和硅铝比有差异。在优化的反应条件下合成的高硅丝光沸石硅铝比达30左右。低温氮吸附与27Al魔角旋转核磁谱表征证实该沸石骨架结构完美,孔道开放畅通,其水热稳定性优于低硅丝光沸石。     

Direct conversion of methane to methanol over Cu exchanged mordenite: Effect of counter ions

Direct conversion of methane(CH4)to methanol(DMTM)is a promising,but very challenging process for the utilization of abundant CH4 as a low carbon resource.In this context,Cu loaded zeolites,mordenite(MOR)in particular,were recognized as the most effective system to perform DMTM.In this work,different Cu salts were used to exchange with MOR,by which the effect of counter ions on the catalytic performance towards DMTM was investigated.The prepared catalysts were characterized and evaluated systematically.It was found that the counter ions affected the speciation of Cu sites,probably due to their capability in extraction of protons from MOR and the influence on the hydrolysis state of the Cu2+in aqueous solution.These behaviors adjusted the association between Cu2+and the exchangeable protons in MOR.As a result,varied DMTM performance was observed.Among the used Cu salts,Cu(CH3COO)2 exchanged MOR showed the highest performance,achieving stable CH3 OH yield of 117±28μmol/g in 5 consecutive cycles,these values are among the highest for Cu loaded MOR zeolites in open publications.     

Electropolymerization of Metallophthalocyanines Carrying Redox Active Metal Centers and their Electrochemical Pesticide Sensing Application

In this study, modified electrodes were constructed with the electropolymerization of metallophthalocyanines (MPcs) carrying redox active metal cations and electropolymerizable substituents. Then these electrodes were tested as selective and sensitive electrochemical pesticide sensors. Incorporation of the redox active Co(II) (CoPc(MOR‐NAF)), Cl–Mn(III) (MnPc(MOR‐NAF)), and Ti(IV)O (TiOPc(MOR‐NAF)) metal cations into Pc cavity increased the redox activity of Pc ring. Moreover, redox active and electropolymerizable 5‐{[(1E)‐(4‐morpholin‐4‐ylphenyl)methylene]amino}‐1‐naphthoxy substituents (MOR‐NAF) on the Pc ring triggered coating of the complexes on the electrode surface with the electropolymerization reactions. Therefore, modified electrodes GCE/MPc(MOR‐NAF) were constructed with the electropolymerizations of MPcs. These electrodes illustrated reasonable redox activity and conductivity for the potential applications in different fields of the electrochemical technologies. Pesticide sensing measurements indicated that changing the metal center of the complexes significantly altered their sensing activities. Among the complexes, GCE/CoPc(MOR‐NAF) electrode behaved as the most sensitive and selective electrode and it sensed the parathion with good selectivity and sensitivity. GCE/CoPc(MOR‐NAF) electrode showed a wider linear range (0.075‐5.75 μmoldm⁻³) and smaller LOD (0.025 μmoldm⁻³) and higher sensitivity (3.46 Acm⁻²M⁻¹) for the parathion sensing. Although GCE/TiOPc(MOR‐NAF) electrode also sensed the parathion with a high sensitivity, its selectivity was poor and the linear range of this sensing was very narrow. Differently GCE/Cl–MnPc(MOR‐NAF) electrode only sensed eserine with reasonably sensitivity.