Y分子筛/介孔Al-SBA-15复合材料与脱铝Y分子筛的表征和重油加氢裂化性能

采用两步法和水热-化学方法制备了具有高水热稳定性的Y分子筛/介孔Al-SBA-15复合材料和含有介孔的脱铝Y分子筛,用浸渍法制备了加氢裂化催化剂,并利用XRD、N2 吸附、SEM、XRF和TEM等分析手段对Y分子筛/介孔Al-SBA-15复合材料、含有介孔的脱铝Y分子筛及其催化剂的物化性质进行了对比分析。相同条件下催化剂的重油加氢裂化性能对比评价结果表明,以Y分子筛/介孔Al-SBA-15复合材料为载体的加氢裂化催化剂的中间馏分油收率和中油选择性高达66.21%和84.5%,比以脱铝Y分子筛为载体的催化剂分别提高了5.68%和5.7%。     

Nafion-H as catalyst for isobutane/2-butene alkylation compared with a cerium exchanged Y zeolite

A solid superacidic Nafion-H polymer was examined as a catalyst for isobutane/2-butene alkylation and compared with a cerium-exchanged Y zeolite. Both catalysts demonstrate initial alkylation activity with rapid decrease in alkylation selectivity. The total product distributions were found to be significantly different after three hours of reaction. Nafion-H showed less selectivity towards iso-octanes, but formed relatively more 2,2,4-trimethylpentane. The differences between the two catalysts suggest dissimilar favoured reaction mechanisms.     

Stellerite-seeded facile synthesis of zeolite X with excellent aqueous Cd2+ and Ni2+ adsorption performance

Zeolite X was synthesized by a two-step hydrothermal method using natural stellerite zeolite as the silicon seed, and its adsorption performance for Cd²⁺ and Ni²⁺ ions was experimentally and comprehensively investigated. The effects of pH, zeolite X dosage, contact time, and temperature on adsorption performance for Cd²⁺ and Ni²⁺ ions over were studied. The adsorption process was endothermic and spontaneous, and followed the pseudo-second-order kinetic and the Langmuir isotherm models. The maximum adsorption capacitiesfor Cd²⁺ and Ni²⁺ ions at 298 K were 173.553 and 75.897 mg·g^-1, respectively. Ion exchange and precipitation were the principal mechanisms for the removal of Cd²⁺ ions from aqueous solutions by zeolite X, followed by electrostatic adsorption. Ion exchange was the principal mechanisms for the removal of Ni²⁺ ions from aqueous solutions by zeolite X, followed by electrostatic adsorption and precipitation. The zeolite X converted from stellerite zeolite has a low n(Si/Al), abundant hydroxyl groups, and high crystallinity and purity, imparting a good adsorption performance for Cd²⁺ and Ni²⁺ ions. This study suggests that zeolite X converted from stellerite zeolite could be a useful environmentally-friendly and effective tool for the removal of Cd²⁺ and Ni²⁺ ions from aqueous solutions.     

MoS2/Y分子筛微生物电解池阴极材料制备及其电化学性能

采用水热法合成了一系列不同比例的MoS₂/Y分子筛复合物,并将其制成碳基复合电解池阴极。线性扫描伏安法（LSV）测试表明,当MoS₂和Y分子筛质量比为5∶2、碳纸负载量为1.5mg/cm²时,阴极催化析氢性能最佳。通过SEM、TEM、XRD、XPS和BET对复合材料进行表征,SEM测试表明MoS₂/Y分子筛为片状和八面体相互交织叠加的云状形貌。BET测试表明其具有排列规整的微孔-介孔多级孔道结构,利于加速H⁺还原和H₂扩散。本文还考察了以MoS₂/Y分子筛作为微生物电解池（MEC）阴极的析氢性能。在MEC运行5个周期的产氢实验中,MoS₂/Y分子筛所产生的平均最大电流密度、氢气产率和产氢量等都高于Pt电极,且具有长期稳定性。因此,MoS₂/Y分子筛是一种适于实际应用的析氢催化剂。     

低液固比体系高岭土微球原位合成Y沸石

以高岭土微球为全部硅铝原料,经焙烧、碱抽提、水热处理等工艺,直接原位晶化合成了Y分子筛。扫描电镜分析表明：在高岭土微球上均匀生成了晶型完整、粒度为1 μm左右的Y分子筛。结合X射线测试方法详细研究了体系硅铝比、碱度、碱抽提时间、导向剂构成及添加时间对Y分子筛合成的影响。研究表明：该水热反应体系的最佳配比为n(SiO2)/n(Al2O3)=10.0。反应适宜的碱度条件为：n(Na2O)/n(SiO2)=0.56,n(H2O)/n(Na2O)= 35,碱度过高或过低都易有P杂晶生成。碱抽提过程对合成Y分子筛十分关键,最佳的抽提时间控制在12 h。导向剂构成为透明高清状,加入时间控制在碱抽提结束时最优,此时合成的Y分子筛品质最好。     

改性沸石处理含镍废水的研究

用丁二酮肟(DMG)修饰经十六烷基三甲基溴化铵(CTAB)改性的人造沸石吸附模拟废水中的Ni2+。结果表明,吸附时间为50 min,改性沸石用量为1.1 g,Ni2+初始浓度为20 mg/L,pH值为7.0,温度为35℃,溶液体积为25 mL时,吸附率达98%以上,且受其他干扰离子(Cu2+、Pb2+)的影响不大。     

苯分子在Y沸石中跳跃扩散机制的动力学Monte Carlo模拟

利用动力学Monte Carlo （KMC）模拟方法计算了苯在Y沸石中扩散的自扩散系数,并考察了3种不同W-W位间跳跃扩散机制下的自扩散系数及其对温度和浓度的依赖关系.实验测量结果表明,苯在Y沸石中的长程运动主要是经S_Ⅱ-W-S_Ⅱ笼间的跳跃,基本不发生W-W之间的跳跃.相应得到的自扩散系数对温度的依赖关系较接近实验值;自扩散系数浓度依赖变化趋势为：先随覆盖量的增加而减小,到覆盖量大于S位的饱和覆盖量（每个超笼中4个分子）后,则随覆盖量增加先增后减,但也不会大于零覆盖量时扩散系数值,该情形与考虑W-W之间跳跃时完全不同.此外,模拟结果表明,使用正确的跳跃机制是KMC方法能正确模拟客体分子在沸石内扩散行为的关键.     

Identification of Pd3+ ions in zeolite L by temperature programmed reduction and electron paramagnetic resonance spectroscopy

Pd supported on KL zeolite has been studied by temperature programmed reduction (TPR) and electron paramagnetic resonance (EPR) spectroscopy. It has been found that upon calcination in pure oxygen Pd³⁺ and Pd²⁺ ions are formed; the Pd³⁺ ions are identified by their EPR signal. As Pd³⁺ ions in the cancrinite cages are difficult to reduce, the H₂ consumption in conventional TPR is below the stoichiometric amount.     

Catalytic activity and stability of Y zeolite for phenol degradation in the presence of ozone

As a stable microporous material, de-aluminated Y zeolite has been used for the first time as an ozonation catalyst and showed remarkable activity for the removal of phenol and chemical oxygen demand (COD) in aqueous solution. The Y zeolite exhibited excellent repetitive-use performance even after continuous operation for 10 cycles. The ozone decomposition rate, influence of hydroxyl radical scavenger and influence of reaction temperature were investigated. The results indicate that Y zeolite accelerates the decomposition of ozone and the generation of hydroxyl radicals, consequently enhances the degradation of phenol and the removal of COD.     

Y／BAPO-5双结构分子筛的制备及催化合成长链烷基苯

采用水热合成法制备Y／BAPO-5双结构分子筛催化剂,并通过X射线衍射（XRD）进行表征。采用固定床反应器考察了Y／BAPO-5催化剂催化苯和长链烯烃合成长链烷基苯的反应活性,根据实验确定了最佳工艺条件：Y沸石的最佳负载质量分数30％,催化剂粒度（60～80）目,用量10mL,空速1h^-1,n（苯）：n（长链烯烃）=8：1,反应温度200℃,压力1.0MPa。在此条件下,长链烯烃转化率可高达99．56％。     

Faujasite zeolite decorated with cobalt ferrite nanoparticles for improving removal and reuse in Pb2+ ions adsorption

Water pollution caused by heavy metals ions has been gaining attention in recent years, increasing the interest in the development of methodologies for their efficient removal focusing on the adsorption process for these purposes. The current challenge faced by adsorption processes is the adequate adsorbent immobilization for removal and reuse. Thus, the present work aimed at producing a faujasite zeolite nanocomposite decorated with cobalt ferrite nanoparticles for Pb~(2+) ions adsorption in an aqueous medium improving magnetic removal and reuse.As a result, a high surface area(434.4 m~2·g~(-1)) for the nanocomposite and an 18.93 emu·g~(-1) saturation magnetization value were obtained, indicating magnetic removal in a promising material for adsorption process. The nanocomposite regeneration capacity evaluated by magnetic recovery after 24 h suspension presented a high Pb~(2+) ion adsorptive capacity(98.4%) in the first cycle. Around 98% of the Pb~(2+) ions were adsorbed in the second cycle. In this way, the synthesized faujasite:cobalt ferrite nanocomposite reveals itself as a promising alternative in adsorption processes, aiming at a synergic effect of FAU zeolite high adsorptive activity and the cobalt ferrite nanoparticles magnetic activity, allowing for adsorbent recovery from the aqueous medium via magnetic force and successive adsorptive cycles.     

Mg改性L分子筛负载Pt重整催化剂的制备及其石脑油芳构化性能

为克服常规氧化铝型重整催化剂氯离子流失及对设备产生腐蚀等问题，通过离子交换法制备了Mg²⁺改性的L分子筛，采用浸渍法制备了不含氯离子的Pt/MgL重整催化剂，对分子筛载体进行了XRD、N₂吸附-脱附、NH₃-TPD和Py-IR等表征，并以硫含量0.50μg/mL工业精制石脑油为原料在固定床微反装置上评价了催化剂重整芳构化性能。结果表明，Mg²⁺离子交换对L分子筛的骨架结构没有破坏，Mg²⁺的存在提高了载体的酸量和酸强度，Mg²⁺改性的Pt/MgL催化剂重整芳构化性能明显提高，适当强酸性对L分子筛重整催化剂芳构化反应起到显著的促进作用。     

Multicomponent ion exchange isotherms in NaX zeolite: evaluation of Cr/Ca/Mg,Cr/Ca/K and Cr/Mg/K systems

BACKGROUND: One of the most important heavy metals is Cr³⁺, which is commonly found together with Ca²⁺, Mg²⁺ and K⁺ ions in tannery wastewaters. Such metals can be removed through ion exchange process using zeolite NaX. Unfortunately, with single exchange mechanisms it is impossible to predict muti‐component and competitive interactions. This work is aimed at overcoming this problem. Ion exchange isotherms of Cr³⁺, Mg²⁺, Ca²⁺ and K⁺ in ternary mixtures (Cr/Mg/Ca, Cr/Ca/K, Cr/Mg/K) using NaX zeolite at 30 °C, 45 °C and 60 °C are studied and reported. RESULTS: Ion exchange is dependent on temperature, and on the nature and interaction of ingoing cations. Sequential ion exchange occurs where one cation is able to displace another already located in the site. Values of the equilibrium constant of all cations investigated are close to each other, which indicates a weak preference for Cr⁺³. The affinity order is as follows: for Cr/Ca/Mg–NaX isotherms, Cr³⁺ > Ca²⁺ > Mg²⁺ at 30 °C, Ca²⁺ > Cr³⁺ > Mg²⁺ at 45 °C and Ca²⁺ > Mg²⁺ > Cr³⁺ at 60 °C. For Cr/Ca/K–NaX isotherms the sequence is Cr³⁺ > Ca²⁺ > K⁺ for the three temperatures and for Cr/Mg/K–NaX isotherms, Cr³⁺ > Mg²⁺ > K⁺ at 30 and 45 °C and Mg²⁺ > K⁺ > Cr³⁺ at 60 °C. CONCLUSION: It can be concluded that ions with a high charge such as Cr³⁺ are not always preferentially removed from multi‐component solution. Therefore, exchanges in NaX zeolite are useful when there is no need to have high chromium removal when compared to the competitive cations investigated here. Copyright © 2008 Society of Chemical Industry     

Catalytic performance and QXAFS analysis of Ni catalysts modified with Pd for oxidative steam reforming of methane

Pd–Ni bimetallic catalysts prepared by co-impregnation and sequential impregnation methods were compared in the catalytic performance in oxidative steam reforming of methane. The sequential impregnation was more effective to the suppression of hot spot formation. According to the structural analysis by in situ quick-scanning X-ray absorption fine structure (QXAFS) during the temperature programmed reduction, the sequential impregnation method gave the bimetallic particles with higher Pd surface composition because of the low possibility of the Pd–Ni bond formation. Higher surface composition of Pd with higher reducibility than Ni is connected to the enhancement of the catalyst reducibility and the suppression of the hot spot formation.     

The action of vanadium over Y zeolite in oxidant and dry atmosphere

Y zeolite was impregnated with vanadium naphtenate and thermally treated at 720 °C for 5 h in dry air. Calcinated samples were characterized by micropore volume, UV–vis-DRS, cracking of n-butane and isopropylamine decomposition followed by simultaneous DSC–TGA. Results show that in dry air the zeolite is stable even at high vanadium loadings but the metal is able to move on the surface of the catalyst and neutralize acid sites. n-Butane conversion increases with vanadium concentration but this is a result of the metal's dehydrogenation ability. Selectivity to protolytic primary cracking (PPC) products decreases linearly with vanadium concentration as a result of the neutralization of Brønsted acid sites quantified by the isopropylamine test. Rate of cracking vs. number of acid sites shows that on a unit of time (second) approximately only one in seven thousand acid sites measured by the isopropylamine technique is able to crack n-butane by monomolecular protolytic cracking mechanism. Selectivity to hydride transfer (SHT) products remains constant with vanadium concentration except at high loadings. Vanadium is able to move on surface and neutralize preferentially acid sites where more energy is released in the reaction with isopropylamine; acid sites strong enough to crack n-butane. Neutralization of acid sites is probably the first step in Y zeolite destruction under conditions predominant in the regenerator of an FCC plant.     

Y型分子筛微波法改性及其选择性吸附脱硫性能

通过微波法进行液态离子交换对NaY分子筛进行改性,采用静态实验对不同吸附剂的脱硫性能进行了考察,筛选出Ce(Ⅳ)-Y吸附性能最好。采用固定床技术对Ce(Ⅳ)-Y的吸附脱硫能力进行了研究,同时运用程序升温脱附法（TPD）和频率响应方法（FR）对吸附脱硫机理进行了进一步探讨。采用微波法进行离子交换改性后的Ce(Ⅳ)-Y分子筛的离子交换度与传统水热法比较有明显提高,吸附容量较NaY有显著提高。     

The removal of iron and cobalt from aqueous solutions by ion exchange with Na‐Y zeolite: batch,semi‐batch and continuous operation

The removal of single component and binary mixtures of divalent cobalt and iron from water by ion exchange with synthetic Y zeolite has been studied in batch, semi‐batch and continuous modes of operation; the initial metal solution concentration did not exceed 2 mmol dm^?3. Binary Co/Na and Fe/Na ion exchange equilibrium isotherms (294 K) are presented wherein exchange site heterogeneity is evident in the case of the iron treatment. Under conditions of stoichiometric ion exchange, removal efficiencies for both cobalt and iron decrease with increasing metal concentration (0.2–2 mmol dm^?3) and the values were similar for both metals. Removal of cobalt under transient conditions was found to be temperature dependent. In the fixed bed operation, break‐through behavior was sensitive to changes in both flow rate and inlet concentration. The break‐through profiles for both metals under competitive and non‐competitive conditions are presented; iron removal is lower in the presence of cobalt and vice versa. An in situ regeneration of the fully loaded zeolite by back exchange with sodium is considered and the exchange capacity of the regenerated zeolite is reported. The feasibility of employing cycles of heavy metal uptake/zeolite regeneration is addressed. © 2002 Society of Chemical Industry     

Effect of Ca2+ and Mg2+ ions on the sintering and spectroscopic properties of cr-doped yttrium aluminum garnet ceramics

In this work, we investigated the effects of Ca²⁺ and Mg²⁺ ions and annealing temperature on the spectroscopic parameters of chromium-doped yttrium aluminum garnet ceramics (Cr:YAG). Samples were obtained with either a separate or a simultaneous addition of calcium and magnesium oxides. To achieve this, aqueous suspensions were prepared using Y₂O₃, Al₂O₃, Cr₂O₃, MgO, and CaO high-purity powders as raw materials. The obtained suspensions were freeze-granulated, pressed into pellets, debinded, and subjected to reactive sintering in vacuum at 1715°C for 6 h. Each material was annealed in air with temperatures between 1300 and 1700°C. Samples were also compared to Cr:YAG ceramics with the addition of silica as a sintering aid. All the materials obtained were then exposed to 445 nm excitation, and emission spectra in the visible and infrared wavelengths were recorded. The results showed that the emission spectra of Cr:YAG ceramics varied according to the annealing conditions: as-sintered samples exhibited strong emissions of around 680 nm and, after air annealing, of around 1400 nm. This phenomenon is attributed to the Cr³⁺→Cr⁴⁺ transition. Samples doped solely with MgO exhibited the highest emission intensity in the infrared region. Thus, Mg²⁺ ions provided the best conversion efficiency of chromium ions.     

Charge reduction and regeneration in K+, Na+, Mg2+, Ni2+ and Co2+-exchanged Wyoming Bentonite

Controlled calcination of ion-exchanged Wyoming Bentonite in the presence and absence of ammonia leads to layer charge reductions. Detailed chemical analyses of both unexchangeable and exchangeable species lead to the conclusion that in no case is there migration of the original interlamellar cations into the octahedral region of the layers although, in terms of ionic radius alone, Mg²⁺, Ni²⁺ and, possibly Co²⁺, might be expected to do so. The production of unexchangeable Mg, Ni or Co, is identified as resulting from high temperature hydrolysis leading to hydroxide or oxide formation.     

提高复合驱油体系的抗钙镁能力研究

针对中原油田的胡状原油 ,在已筛选出SD驱油剂的基础上 ,在配方中添加两性离子表面活性剂 ,使原有配方的抗钙镁能力由 35 0mg/L提高到 2 0 0 0mg/L。并在SD复合驱油体系中进行了阳离子聚合物抗钙镁能力的研究。