以稻壳为原料合成等级孔Y型分子筛

以稻壳为原料,通过高温碱活化提取稻壳中的硅作为分子筛合成的硅源,利用碳化稻壳中的碳作为介孔模板合成具有等级孔结构的Y型分子筛。采用XRD、N_2吸附-脱附等表征合成的Y型分子筛。考察碱度、晶化时间、晶化温度等合成条件对Y型分子筛结构特性的影响。结果表明,随着碱度的增加,分子筛结晶度先增加后降低。碱度为6.66时,合成的Y型分子筛结晶度最高。当晶化温度为90℃、时间为16 h时,合成的分子筛中含有较少的杂晶。     

Rhodium supported in basic zeolite Y: A selective and stable catalyst for CO hydrogenation

Catalysts prepared by a condensation reaction of Rh(CO)₂(acac) within the supercages of zeolite Y made basic by treatment with NaN₃ are active for CO hydrogenation and selective for low-molecular-weight olefins and methanol. High partial pressures of CO (or CO + H₂) stabilize the catalyst. The predominant species in the catalyst are suggested to be rhodium carbonyl clusters trapped in the zeolite cages.     

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。     

Controllable fabrication and catalytic activity of highly b‐oriented HZSM‐5 coatings

Multilayer b‐orientated HZSM‐5 catalytic coating is controllably synthesized by repeated growth of zeolite layer on Ti?OH‐modified surface of sublayer. The as‐prepared zeolite coating shows performance enhancement up to 110% in catalytic cracking of n‐dodecane ascribed to enhanced mass transfer in its straight and short pathway along the b‐axis. © 2014 American Institute of Chemical Engineers AIChE J, 60: 1964–1968, 2014     

改性Y型分子筛非临氢催化脱除重整芳烃中的烯烃

研究以NaY分子筛粉与Al₂O₃混合成型后离子交换,引入AlF₃和少量稀土（La、Ce）增加催化剂的酸性以提高脱烯烃性能,制备出简单高效的非临氢芳烃脱烯烃催化剂。采用NH₃-TPD、XRF、Py-IR和XRD对催化剂进行表征,结果表明,引入AlF₃后,催化剂的总酸量增加和L酸酸量增加,B酸酸量减少;引入适量La和Ce组分后,催化剂上中强酸量和B酸酸量增加。以La和Ce改性的催化剂对溴指数540.0 mg·（100g油）^-1的原料脱烯烃,产品分布基本无变化,溴指数约稳定在9.0 mg·（100g油）^-1。改性催化剂总酸量多、合适中强酸量以及适当提高B酸酸量有利于催化剂脱烯烃性能。     

Inorganic–organic hybrid materials based on functionalized silica and carbon: A comprehensive understanding toward the structural property and catalytic activity difference over mesoporous silica and carbon supports

Inorganic–organic hybrid materials based on functionalized silica and carbon were synthesized by anchoring molybdovanadophosphoric acid (H₅[PMo₁₀V₂O₄₀] · 32.5H₂O) onto amine-functionalized SBA-15, ethane-bridged SBA-15 and mesoporous carbon, respectively. Small angle X-ray diffraction, N₂ sorption analysis, HRTEM, SEM, FT-IR, CP-MAS NMR were used to diagnose the mesoporous structure of inorganic–organic hybrid materials. The structural integrity of molybdovanadophosphoric acid has been found to be retained after immobilization over mesoporous materials. These inorganic–organic hybrid materials were tested in the environmentally friendly oxidation of 2-methylnaphthalene (2MN) with 30% aqueous hydrogen peroxide. Molybdovanadophosphoric acid containing mesoporous organosilica hybrid material (ethane-bridged SBA-15) exhibited higher catalytic activities in the oxidation of 2MN to give a clean product 2-methy-1,4-naphthoquinone (menadione vitamin K3 precursor), because of the improved hydrophobicity of the material. The correlation between structural properties and catalytic activities of these hybrid materials has been well addressed in our present studies.     

镧和铈在Y型分子筛方钠石笼中的定位差异以及对FCC催化剂反应性能的影响

用新型制备工艺分别制备镧和铈改性的Y型分子筛,并通过X衍射法、分光光度法和ACE反应评价等手段考察两种稀土元素在Y型分子筛中的定位状况、制备过程中的利用率、水热稳定性以及反应性能的差异。研究发现,镧在较低能耗条件下容易实现在Y型分子筛方钠石笼中的定位。同时,镧改性的Y型分子筛还具有稀土利用率高、热和水热稳定性好等特点。ACE评价结果表明,镧改性Y型分子筛制备的催化剂在反应性能上有明显优势。     

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     

Nano‐hydroxyapatite (HAp) and hydroxyapatite/platinum (HAp/Pt) core shell nanorods: Development,structural study,and their catalytic activity

The development of a new kind of material that is a nanostructured catalytic material with an environmentally benign nature that can be used for alternative energy has acquired significance in recent years. In this context, the use of heterogeneous catalysts for the transesterification of vegetable oils has gained prominence due to their eco‐friendly and reusable nature. Hence in the present study, pure hydroxyapatite (HAp) and hydroxyapatite/platinum (HAp/Pt) nanostructured particles have been prepared successfully through a facile chemical method without templates and surfactants and their catalytic activity investigated for transesterification of natural vegetable oil to bioenergy (biodiesel). The textural and structural features of pure HAp and HAp/Pt were investigated using various characterization techniques such as x‐ray diffraction, Fourier transform infrared (FTIR) and Raman spectroscopy, field emission scanning electron microscopy (FESEM), and transmission electron microscopy (TEM). The elements present in the prepared nanostructures were confirmed through energy dispersive spectroscopy (EDS) and x‐ray photoelectron spectroscopy (XPS) techniques. The XPS analysis also confirms the metallic nature of the platinum in HAp/Pt. The specific surface area and porous nature of the prepared nanostructured catalysts were studied using the N₂ physisorption Brunauer‐Emmett‐Teller‐Barrett‐Joyner‐Halenda (BET‐BJH) method. The catalytic activity of the pure HAp nanoparticles and HAp/Pt core shell nanorods with the Simarouba glauca plant seed oil was investigated. The obtained results indicate that the pristine HAp nanoparticles and HAp/Pt core shell nanorods (NRs) show 91.4% and 87.1% fatty acid methyl ester (FAME) conversion, respectively, potentially offering environmental benign biocatalysts for biofuel production from natural feed stock.     

Density functional theory study on catalytic cracking of n‐hexane on heteropoly acid: A comparison with acidic zeolite

We have performed a direct comparison of n‐hexane cracking catalysed by a zeolite (H‐ZSM‐5) and a heteropoly acid (phosphotungstic acid, HPW). This comparison was examined by employing density functional theory, including dispersion energy, M06‐L, for the purpose of understanding these two catalysts for this industrially important reaction. The predicted adsorption energies of hexane are ?21.4 and ?6.8 kcal/mol for H‐ZSM‐5 and HPW, respectively. The protolytic cracking mechanism is proposed to proceed via the first step of the C–C activation and is found to be the rate‐determining step with activation energies of 42.8 and 41.4 kcal/mol for H‐ZSM‐5 and HPW, respectively. We also discuss the advantages and disadvantages of both catalysts for hydrocarbon cracking and give a perspective of utilising cutting‐edge molecular design for a tailor‐made hybrid catalyst. © 2011 Canadian Society for Chemical Engineering     

Synthesis of ZSM‐5 from diatomite: a case of zeolite synthesis from a natural material

A highly crystalline ZSM‐5 product was obtained from diatomite, a natural raw material, both with and without the presence of diethanolamine. The synthesis process took 40 h, and was carried out under hydrothermal conditions, at autogenic pressure, and at a temperature of 180 °C. The resulting crystals were identified as ZSM‐5 by X‐ray diffraction and characterized by scanning electron microscopy, infrared spectroscopy, thermal gravimetry and differential thermal analysis. Copyright © 2004 Society of Chemical Industry     

Study of operating variables in the transformation of aqueous ethanol into hydrocarbons on an HZSM‐5 zeolite

With the aim of determining the possibilities of directly upgrading the liquid obtained from carbohydrate fermentation, the effect of operating conditions (temperature, space time, water content in the feed) has been studied in the catalytic transformation of aqueous ethanol into hydrocarbons on an HZSM‐5 zeolite in an isothermal fixed bed reactor. Special attention has been paid to the effect of water content on the yield, product distribution and catalyst deactivation. Although deactivation by coke decreases as the water content is increased, this content must be limited at 450 °C and higher temperatures in order to avoid irreversible deactivation of the catalyst by dealumination. © 2002 Society of Chemical Industry     

Olefin production by cofeeding methanol and n‐butane: Kinetic modeling considering the deactivation of HZSM‐5 zeolite

The joint transformation of methanol and n‐butane fed into a fixed‐bed reactor on a HZSM‐5 zeolite catalyst has been studied under energy neutral conditions (methanol/n‐butane molar ratio of 3/1). The kinetic scheme of lumps proposed integrates the reaction steps corresponding to the individual reactions (cracking of n‐butane and MTO process at high‐temperature) and takes into account the synergies between the steps of both reactions. The deactivation by coke deposition has been quantified by an expression dependent on the concentration of the components in the reaction medium, which is evidence that oxygenates are the main coke precursors. The concentration of the components in the reaction medium (methanol, dimethyl ether, n‐butane, C₂? C₄ paraffins, C₂? C₄ olefins, C₅? C₁₀ lump, and methane) is satisfactorily calculated in a wide range of conditions (between 400 and 550°C, up to 9.5 (g of catalyst) h (mol CH₂)^?1 and with a time on stream of 5 h) by combining the equation of deactivation with the kinetic model of the main integrated process. © 2010 American Institute of Chemical Engineers AIChE J, 2011     

A new atom transfer radical polymerization initiator based on phenolphthalein for the synthesis of bis‐allyloxy functionalized polystyrene macromonomers

A new atom transfer radical polymerization (ATRP) initiator, namely 2‐(1,1‐bis(4‐(allyloxy)phenyl)‐3‐oxoisoindolin‐2‐yl)ethyl 2‐bromo‐2‐methylpropanoate, was synthesized starting from phenolphthalein, a commercially available and an inexpensive chemical. Well‐ defined bis‐allyloxy functionalized polystyrene macromonomers (M_n,GPC 4800–11 700 g mol^?1) with controlled molecular weight and narrow molecular weight distribution (1.05–1.09) were synthesized using ATRP by varying the monomer to initiator feed ratio. The presence of allyloxy functionality on polystyrene was confirmed by Fourier transform infrared and ¹H NMR spectroscopy. A kinetic study of polymerization revealed pseudo‐first‐order kinetics with respect to monomer consumption. Initiator efficiency was found to be in the range 0.80–0.95. Matrix‐assisted laser desorption ionization time of flight spectra showed a narrow molecular weight distribution with control over the molecular weight. The reactivity of the allyloxy groups on polystyrene was successfully demonstrated by quantitative photochemical thiol‐ene click reaction with benzyl mercaptan as the model thiol reagent. Furthermore, the thiol‐ene click reaction was exploited to introduce other reactive functional groups such as hydroxyl and carboxyl by reaction of α,α′‐bis‐allyloxy functionalized polystyrene with 2‐mercaptoethanol and 3‐mercaptopropionic acid, respectively. © 2014 Society of Chemical Industry     

Application of lipase immobilized on nylon‐6 for the synthesis of butyl acetate by transesterification reaction in n‐heptane

A purified alkaline thermotolerant bacterial lipase from Bacillus coagulans BTS‐3 was immobilized on nylon‐6 matrix activated by glutaraldehyde. The matrix showed ～ 70% binding efficiency for lipase. The bound lipase was used to perform transesterification in n‐heptane. The reaction studied was conversion of vinyl acetate and butanol to butyl acetate and vinyl alcohol. Synthesis of butyl acetate was used as a parameter to study the transesterification reaction. The immobilized enzyme achieved ～ 75% conversion of vinyl acetate and butanol (100 mmol/L each) into butyl acetate in n‐heptane at 55°C in 12 h. When alkane of C‐chain lower or higher than n‐heptane was used as an organic solvent, the conversion of vinyl acetate and butanol to butyl acetate decreased. During the repetitive transesterification under optimal conditions, the nylon bound lipase produced 77.6 mmol/L of butyl acetate after third cycle of reuse. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007     

Effects of in situ esterification on the performance of carboxyl functionalized rubber‐modified epoxy film adhesives

Epoxy‐based film adhesive formulations were developed with 10 wt % solid carboxyl functional rubber. Due to the high rubber content and resulting viscosity restrictions, the rubber could not be prereacted with the epoxy before hot‐melt filming. Therefore, an esterification catalyst was used to perform this reaction in situ before the epoxy curing reactions. The performance of this adhesive system is compared to that of one without the esterification catalyst. A significant difference in the flow characteristics was observed with incorporation of the esterification catalyst, but only small variations in mechanical performance were found. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 728–734, 2000     

Amine‐functionalized mesoporous silica: A material capable of CO2 adsorption and fast regeneration by microwave heating

The surface of ordered mesoporous (MCM‐48) silica has been subjected to covalent grafting with silane molecules containing one to three amino groups. The dielectric properties of the materials were studied in detail, and the functionalized materials were used for CO₂ adsorption at room temperature, followed by regeneration under either conventional heating or microwave irradiation. It has been found that, as the intensity of functionalization with amino groups increases (from mono‐ to tri‐amino silanes) both the CO₂ load and the dielectric response at microwave frequencies increase. In particular, functionalization with a tri‐amino silane derivative gave the highest CO₂ adsorption and the fastest microwave heating, resulting in a fourfold acceleration of adsorbent regeneration. The grafted material was fully stable for at least 20 adsorption‐regeneration cycles, making it an ideal candidate for microwave‐swing adsorption (MWSA) processes. © 2015 American Institute of Chemical Engineers AIChE J, 62: 547–555, 2016     

Chemical composition distribution study in ethylene/1‐hexene copolymerization to produce LLDPE material using MgCl2‐TiCl4‐based Ziegler‐Natta catalysts

The characteristic features of LLDPE polymerization with ZN catalyst are the time drift effect during polymerization and the bending effect when trying to decrease density of the copolymer by adding more comonomer to the polymerization. The time drift in LLDPE polymerization is revealed by a constant decrease of comonomer incorporation during polymerization time. The bending is revealed by difficulties in lowering the density of LLDPE material below the density of 920 kg/m³. With increasing comonomer content during polymerization, the density does not decrease, but the soluble fraction increases. To try to observe if these phenomena are connected, two types of catalysts, SiO₂ supported and precipitated MgCl₂ ZN catalysts, were studied. A short time (10 min) and an extended time (60 min) copolymerization test series where the polymerizations were performed in the presence of a gradually increasing comonomer amount. Both catalysts show a strong bending when density is presented as a function of 1‐hexene both in 10‐ and 60‐min polymerization, indicating no connection between time drift and bending. The density, melting point, and crystallinity results all indicate that both catalysts are making similar copolymer material with identical chemical composition distribution. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Kinetic study of the manganese‐based catalytic hydrogen peroxide oxidation of a persistent azo‐dye

BACKGROUND: The discharge of synthetic dyes by the textile industry into the environment poses concerns due to their persistence and toxicity. New efficient treatment processes are required to effectively degrade these dyes. The aim of this work was to study the degradation of a persistent dye (Drimarene Brilliant Reactive Red K‐4BL, C.I.147) using H₂O₂ oxidation catalysed by an Mn(III)‐saltren catalyst and to develop a kinetic model for this system. RESULTS: Dye oxidation with H₂O₂ was significantly improved by the addition of the catalyst. As the pH was increased from 3 to 10, the oxidation rates increased significantly. The kinetic model developed in this study was found to adequately explain the experimental results. In particular, dye oxidation can be described at high pH by pseudo‐first‐order kinetics. A Michaelis–Menton type equation was developed from the model and was found to adequately describe the effect of H₂O₂ and catalyst concentrations on the apparent pseudo‐first‐order rate constant. Optimum catalyst and H₂O₂ concentrations of 500 mg L^?1 and 6.3 g L^?1, respectively, were found to give maximum reaction rates. CONCLUSION: Catalytic H₂O₂ oxidation was found to be effective for the removal of persistent dye and the results obtained in this work are of significance for design and scale‐up of a treatment process. Copyright © 2009 Society of Chemical Industry