Conversion of propylene into cyclohexane on PtGaZr/SiO2 catalyst

The light olefins present in Delay Coker and fluid catalytic cracker dry gas can be valorized into naphthenes using a new PtGaZr/SiO₂ catalyst. This catalyst was compared to a GaZrSiO₂ catalyst prepared with the same methodology. Both were characterized by XRD, and FTIR, XPS, ⁷¹Ga, ²⁹Si and ¹H NMR spectroscopies. Propylene is treated in the presence of CS₂, hydrogen, and benzene in a semi-batch type reactor and the product composition is analyzed by GC and MS techniques. The different operating variables were explored to study the effect of Pt on activity, selectivity and catalyst stability. The spent catalysts after 10 cycles in operation were analyzed using ¹³C NMR, ¹H NMR, IR, and XPS spectroscopies. The paper discusses the catalytic surface composition, the effect of temperature, contact time, hydrogen partial pressure and benzene in the feed. The study demonstrated that the effect of Pt, hydrogen and benzene is crucial to orient the reaction toward naphthenes production.     

二芳基二硫醚与硝基芳烃的反应

以二芳基二硫醚（ArSSAr）和硝基芳烃（ArNO₂）为原料,在廉价易得的甲醛次硫酸氢钠（Rongalite^®）和碳酸钾（K₂CO₃）共同促进下,以二甲亚砜（DMSO）为溶剂,50℃下合成了一系列非对称二芳基硫醚衍生物,产物结构经¹H NMR和¹³C NMR确证。该方法具有反应条件温和、原料易得和操作简单等优点。     

Solid state multinuclear NMR study of iron species in natural and modified clinoptilolite from Tasajera deposit (Cuba)

The present study has been conducted to elucidate the Fe-sites in natural clinoptilolite, and the possibility to produce a reversible replacement of these atoms in the zeolite framework. In order to achieve these results we have tried to introduce iron in clinoptilolite structure after the almost total extraction of the natural iron species. A sample of the purified natural clinoptilolite from Tasajeras deposit, Central region of Cuba, was modified by a hydrothermal treatment with orthophosphoric acid. Iron exchange forms of the orthophosphoric zeolite were obtained using FeSO₄ and Fe₂(SO₄)₃ solutions. The modified zeolites were studied by multinuclear magnetic resonance (²⁷Al, ²⁹Si, ³¹P MAS NMR and ¹²⁹Xe NMR). Other analytical techniques as Electron Paramagnetic Resonance, X-ray diffraction, Mössbauer and Infrared spectrometry, volumetric measurements and chemical analysis by Induced Plasma Coupled spectroscopy were used to support the results of NMR studies. The presence of iron species with tetrahedral and octahedral coordination in the structure of a natural clinoptilolite has been confirmed. The influence of iron in tetrahedral coordination in the thermal stability of the clinoptilolite structure was also confirmed.     

Spectroscopic analysis of carbon dioxide and nitrogen mixed gas hydrates in silica gel for CO2 separation

In this study solid-state NMR spectroscopy was used to identify structure and guest distribution of the mixed N₂ + CO₂ hydrates. These results show that it is possible to recover CO₂ from flue gas by forming a mixed hydrate that removes CO₂ preferentially from CO₂/N₂ gas mixture. Hydrate phase equilibria for the ternary CO₂–N₂–water system in silica gel pores were measured, which show that the three-phase H–L_w–V equilibrium curves were shifted to higher pressures at a specific temperature when the concentration of CO₂ in the vapor phase decreased. ¹³C cross-polarization (CP) NMR spectra of the mixed hydrates at gas compositions of more than 10 mol% CO₂ with the balance N₂ identified that the crystal structure of mixed hydrates as structure I, and that the CO₂ molecules occupy mainly the abundant 5¹²6² cages. This makes it possible to achieve concentrations of more than 96 mol% CO₂ gas in the product after three cycles of hydrate formation and dissociation.     

Synthesis and characterization of the layered sodium silicate ilerite

A sodium ilerite, molar ratios 1Na₂O:8.2SiO₂:10.2H₂O, was obtained with a good crystalline structure and characterized by several NMR techniques in addition to X-ray diffraction (XRD). The X-ray pattern of the as-synthesized ilerite is in very good agreement with the structure proposed by Gies and coworkers. The narrow ²⁹Si MAS NMR signals (FWHM=0.3 ppm) indicate a good short-range order of the framework. The proton dynamics influences several ²⁹Si NMR parameters. The 16 ppm signal in the ¹H MAS NMR spectra is explained by a proton in a bridging position in the short (2.3 Å) O4–O4 bonding. The quadrupole coupling constant C_qcc=100 kHz with η=0.2 for the 16 ppm signal, which was obtained from the ²H MAS NMR spectra, confirms this explanation. ¹⁷O NMR shows also a separate signal for SiOH groups but cannot resolve the three expected lines for SiOSi. PFG NMR detects a small mobile portion of water in the ilerite, which is located probably on the external surface of the crystallites. An intracrystalline diffusion coefficient of the intercalated water molecules of the order of magnitude 10⁻¹⁵ m² s⁻¹ was obtained by NMR tracer exchange experiments.     

桥联茂金属催化1-癸烯聚合及其产物结构与性能

采用桥联茂金属催化体系rac-Et(1-Ind)₂ZrCl₂/Al(ⁱBu)₃/[Me₂NHPh]⁺[B(C₆F₅)₄]^-催化1-癸烯聚合,考察了茂金属浓度、Al/Zr摩尔比、B/Zr摩尔比、温度、反应时间对反应转化率、黏度和摩尔质量的影响.当反应条件为1-癸烯20mL、甲苯20mL、Zr/烯摩尔比8×10^-5、Al/Zr摩尔比80、B/Zr摩尔比1.5、温度80℃、反应时间1h时,转化率达到96.2%.采用¹³C NMR和¹H NMR表征了产物的结构,优化条件下所得的聚合产物具有高黏度指数(259)和低分子量分布(2.088),可作为理想的润滑油基础油的原料.     

Synthesis and characterization of urea bridged hybrid periodic mesoporous organosilica materials

Urea bridged organic–inorganic hybrid mesoporous SiO₂ materials (U-BSQMs) were synthesized through a sol–gel procedure by co-condensation of bis(triethoxysilyl propyl) urea (BSPU) under basic conditions using cetyltrimethylammonium bromide (CTAB) as organic template. X-ray diffraction (XRD) and transmission electron microscopy (TEM) confirmed the mesoporous structure of the sample. Fourier-transform infrared spectroscopy (FT-IR), solid state CP-MAS NMR spectroscopy of ²⁹Si (²⁹Si CP-MAS NMR) and ¹³C (¹³C CP NMR) indicated that most of the Si–C bonds are unbroken during the synthesis process. The N₂ adsorption–desorption results revealed that these hybrid mesoporous SiO₂ materials have bimodal distribution of pores with pore diameters of 2.4 and 3.8 nm, respectively. Thermogravimetric analysis (TG) demonstrated that about 16% Si–C bonds have been broke during the synthesis progress. This kind of material is expected to find possible application in ion supporting, drug delivery and catalysis.     

Influence of the SiO2/Al2O3 ratio on the synthesis and physicochemical characteristics of levyne-type zeolite

Levyne-type zeolites were synthesized from gels of initial compositions 4.5Na₂O-6MeQI-xAl₂O₃ 30SiO₂-500H₂O, with MeQ = methylquinuclidinium and 0.6 ≤ x ≥ 3 at 150 ≤ t ≥ 190 °C. The ²⁹Si NMR spectra show the presence of two crystallographically different sites in the structure. The ²⁷Al NMR spectra also suggest the presence of two different tetrahedral Al atoms incorporated in the structure. A rather high amount of defect groups SiOM and Si(OM)₂ with M = MeQ, Na and/or H are present in the precursor samples. The Si(OM)₂ groups are eliminated during calcination, and a certain amount of SiOM still persists after calcination. The combined ¹³C NMR and thermal analysis data allowed one to interpret the nature of the two different types of MeQ⁺ ions occluded in the levyne channels.     

Si and Al MAS NMR characterization of non-hydrated zeolites Y upon adsorption of ammonia

Solid-state NMR characterization of zeolite catalysts in the hydrated state is often accompanied by an uncontrolled hydrolysis of the framework. In the present work it is demonstrated that the limitations occurring for ²⁹Si and ²⁷Al MAS NMR spectroscopy of non-hydrated zeolites Y, such as strong decrease of resolution and significant line broadening, can be overcome by loading these materials with ammonia. In the ²⁹Si MAS NMR spectra of non-hydrated and ammonia-loaded zeolites Y, no dehydration-induced high-field shift of Si(nAl) signals (n = 3, 2, 1) occurs, which is generally responsible for the loss of resolution in the spectra of non-hydrated materials. The ²⁷Al MAS NMR spectra of the non-hydrated and ammonia-loaded zeolites Y consist exclusively of signals of the tetrahedrally coordinated framework aluminum atoms with spectroscopic parameters similar to those of framework aluminum atoms in hydrated samples. The framework n_Si/n_Al ratios of the non-hydrated zeolites Y obtained by both ²⁹Si and ²⁷Al MAS NMR spectroscopy upon ammonia-loading agree well with each other.     

Characterization by solid state V NMR spectroscopy

The fresh catalyst V₂O₅–WO₃/TiO₂ and catalyst used in SCR for 9000 h have been studied by the solid state ⁵¹V NMR spectroscopy in static and MAS conditions. According to ⁵¹V NMR in both samples the majority of vanadium sites are in a distorted octahedral environment similar to that in V₂O₅. There is a strong interaction between vanadium oxide and the support, but the concentration of vanadium atoms strongly bound to the surface is very small and can be detected only in MAS NMR experiments or after removing the excess of V₂O₅. There is no influence of WO₃ additives on the structure of the particles of V₂O₅, whereas the influence on the structure of strongly bounded V cannot be excluded. Combination of static (wide line) and MAS NMR techniques permit the characterization of not only the structure of the vanadium species but also small changes in their local environment. Hence these experiments show that there are some distortions of the local environment of vanadium sites of the vanadium oxide particles compared with the polycrystalline V₂O₅; treatment by SCR increases these distortions.     

Synthesis, cure kinetics and thermal properties of the 2,7-dihydroxynaphthalene dicyanate

The novel dicyanate ester resin containing the naphthalene ring (DNCY) was synthesized from 2,7-dihydroxynaphthalene and cyanogen bromide by two-step method. The monomer of DNCY was characterized by FT-IR, ¹H NMR, ¹³C NMR and elemental analyses (EA). The cure behavior of DNCY was studied by means of nonisothermal DSC, and the kinetics parameters were determined by the Kissinger method. The thermal properties of DNCY resin were studied by thermal degradation analysis at a heating rate of 10 °C min⁻¹ both in N₂ (thermal stability) and in air (thermal-oxidative stability). The DNCY resin showed excellent thermal stability, compared with that of bisphenol A dicyanate (BACY) resin, which could be demonstrated by the extensional onset temperature (435.8 °C), the temperature of maximum weight loss rate (450.3 °C) and the percentage char yields at 700 °C (60.5%) in N₂, and thermal-oxidative stability, which could be demonstrated by the extensional onset temperature (435.4 °C), the first temperature of maximum weight loss rate (450.7 °C), the second temperature of maximum weight loss rate (580.0 °C) and the temperature of complete degradation (704.4 °C) in air. The DNCY resin exhibited higher T_g and thermal degradation temperature than BACY resin.     

Water-induced bulk Ba(NO3)2 formation from NO2 exposed thermally aged BaO/Al2O3

Phase changes in high temperature treated (>900 °C) 8 or 20 wt% BaO supported on γ-Al₂O₃ model lean NO_x trap (LNT) catalysts, induced by NO₂ and/or H₂O adsorption, were investigated with powder X-ray diffraction (XRD), solid state ²⁷Al magic angle spinning nuclear magnetic resonance (MAS NMR) spectroscopy, and NO₂ temperature programmed desorption (TPD) experiments. After calcination in dry air at 1000 °C, the XRD and solid state ²⁷Al MAS NMR results confirm that stable surface BaO and bulk BaAl₂O₄ phases are formed for 8 and 20 wt% BaO/Al₂O₃, respectively. Following NO₂ adsorption over these thermally treated samples, some evidence for nanosized Ba(NO₃)₂ particles are observed in the XRD results, although this may represent a minority phase. However, when water was added to the thermally aged samples after NO₂ exposure, the formation of bulk crystalline Ba(NO₃)₂ particles was observed in both samples. Solid state ²⁷Al MAS NMR is shown to be a good technique for identifying the various Al species present in the materials during the processes studied here. NO₂ TPD results demonstrate a significant loss of uptake for the 20 wt% model catalysts upon thermal treatment. However, the described phase transformations upon subsequent water treatment gave rise to the partial recovery of NO_x uptake, demonstrating that such a water treatment of thermally aged catalysts can provide a potential method to regenerate LNT materials.     

Ordered mesoporous aluminosilicates with very low Si/Al ratio and stable tetrahedral aluminum sites for catalysis

New and ordered 2D-hexagonal (p6mm) mesoporous aluminosilicates (CMI-11) have been synthesized in strongly alkaline media using aluminosilicate ester ((Bu^sO)₂-Al-O-Si-(OEt)₃) as single-source molecular precursor and CTMABr as surfactant and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), N₂ adsorption–desorption and ²⁷Al and ²⁹Si MAS NMR spectroscopy. These mesoproous aluminosilicates exhibit a very low Si/Al ratio of 1.9 and highly thermal stable tetrahedral aluminum sites in the mesoporous walls. ²⁷Al and ²⁹Si MAS NMR spectroscopy indicates that the pore walls of CMI-11 are fully condensed with molecular homogeneity of Si–O–Al linkage. These materials are highly important in catalysis, in particular for the petroleum processing and the bulky molecules treatment.     

二氧化碳、碳酸氢盐与有机伯胺和仲胺反应机理

采用停留光谱法和核磁共振(氢谱)法系统地研究了二氧化碳(aq)、碳酸氢盐与一乙醇胺(MEA)、L-氨基丙醇(2-AP)、1-氨基-2-丙醇(1-AP)、N-甲基正丙胺(IBA)、3-氨基丙醇(3-AP)、二乙醇胺(DEA)、吗啉(MORP)、哌啶(PIPD)和4-哌啶甲醇(4-PIPDM)在水溶液中25℃下的反应动力学,阐明其反应机理,给出二氧化碳、碳酸氢盐与有机胺的反应速率常数、氨基甲酸盐质子化常数和氨基甲酸盐的稳定常数。研究发现:二氧化碳与伯胺和仲胺的反应速率常数与其氨基甲酸盐的稳定常数具有线性关系。发现氨基甲酸盐稳定常数代表液态有机胺(氨)分子的空间位阻效应、溶剂化效应和电子效应的协同作用,它对于设计新型液态有机胺分子具有重要理论指导作用。     

超支化镍系催化剂构效关系及催化乙烯齐聚机理

采用1.0G超支化大分子（1.0G）、3-取代水杨醛和NiCl₂·6H₂O为原料,依次经席夫碱反应和络合反应合成了3种新型具有不同取代基位阻的超支化水杨醛亚胺配体及其镍系催化剂,利用红外光谱（FTIR）、核磁共振氢谱（¹H NMR）、紫外光谱（UV-vis）、电喷雾质谱（ESI-MS）及电感耦合等离子体质谱（ICP-MS）等方法对合成出产物的结构进行表征。考察了配体空间位阻、溶剂种类、助催化剂种类及反应条件对催化乙烯齐聚性能的影响。研究结果表明,配体空间位阻对催化乙烯齐聚性能有较大的影响,当以甲苯为溶剂、甲基铝氧烷（MAO）为助催化剂,在最佳反应条件下,超支化邻苯基水杨醛亚胺镍系催化剂催化乙烯齐聚的活性为2.81×10⁵g/(mol Ni·h),对高碳烯烃（C₁₀₊）的选择性为34.28%。此外,在超支化水杨醛亚胺镍系催化剂催化性能评价的基础上,对其催化乙烯齐聚的机理进行研究。     

The synthesis and spectral properties of novel phthalocyanines with pendant bulky units

Novel phthalocyanines with biphenyl substituents and ester groups that are readily soluble in organic solvents were synthesized from a phthalonitrile derivative obtained by displacement of the –CH proton in 1-chloro-3,4-dicyano-6-(1,1-dicarbethoxymethyl)benzene with 4-(chloromethyl)biphenyl, followed by cyclotetramerization in the presence of metal salts {CuCl₂, Pb(CH₃COO)₂·3H₂O, CoCl₂ and Zn(CH₃COO)₂}. Transesterification of malonyl esters occurred during the cyclotetramerization of dinitrile with CuCl₂, Pb(CH₃COO)₂·3H₂O in 1-pentanol in the presence of DBU. The structures of the newly synthesized molecules were verified using elemental analysis, ¹H NMR, FT-IR, MicroTOF mass and UV–vis spectral data.     

V2O5 catalysts supported on Al2O3–SiO2 mixed oxide: V, H MAS solid-state NMR, DRIFTS and methanol oxidation studies

Alumina–silica mixed oxide, synthesized by the sol–gel technique, was used as a support for dispersing and stabilizing the active vanadia phase. The catalysts were characterized employing ⁵¹V and ¹H solid-state MAS NMR, diffuse reflectance FT-IR, BET surface area measurements. The partial oxidation activities of the catalysts were tested using methanol oxidation as a model reaction. ⁵¹V solid-state NMR studies on the calcined catalysts showed the peaks corresponding to the presence of both tetrahedral and distorted octahedral vanadia species at low vanadia loadings and with an increase in V₂O₅ content, the ⁵¹V chemical shifts corresponding to amorphous V₂O₅ like phases were observed. DRIFTS studies of the catalysts indicated the vibrations corresponding tetrahedral vanadia species at low and medium loadings and at high V₂O₅ contents the vibrations corresponding V=O bonds of V₂O₅ agglomerates were observed. The V/Al–Si catalysts exhibited high selectivity for the dehydration product dimethyl ether in the methanol partial oxidation studies showing the predominance of the acidic nature of the alumina–silica support over the redox properties of the active vanadia phase.     

富勒烯对甲基苯胺衍生物的合成及其对硝化棉安定性的影响

以富勒烯(C₆₀)、溴素(Br₂)、八溴富勒烯(C₆₀Br₈)及对甲基苯胺(C₇H₉N)为原料,经两步反应合成了富勒烯对甲基苯胺衍生物C₆₀(NC₆H₄CH₃)_n;采用核磁共振碳谱(¹³C-NMR)、质谱(MS)、X射线光电子能谱(XPS)、傅里叶变换红外光谱仪(FT-IR)以及紫外-可见光分光光度计(UV-Vis)对合成得到的富勒烯对甲基苯胺衍生物结构进行了表征;采用差热分析(DTA)、真空安定性测试(VST)、热重分析(TGA)、甲基紫实验等热分析方法,并结合电子顺磁共振波谱法研究了富勒烯对甲基苯胺衍生物与硝化棉的相互作用规律和机理。结果表明,富勒烯对甲基苯胺衍生物将甲基紫试纸的变色时间由56min延长至95min;将单位质量硝化棉热分解释放的气体量由2.67mL/g降至1.46mL/g;将硝化棉的热失重率由17.17%降至5.46%;当富勒烯对甲基苯胺衍生物的质量浓度为0.76g/L时,其对氮氧自由基的清除率达到50%。表明富勒烯对甲基苯胺衍生物提高了硝化棉的安定性,且安定性能明显优于传统安定剂DPA和C2。     

硅烷芳炔-硅氧烷芳炔嵌段共聚物的合成与表征

合成了不同链段长度的卤代硅氧烷,并用其与间二乙炔基苯格氏试剂反应,合成了两种硅烷芳炔-硅氧烷芳炔嵌段共聚物（SiO-b-PSA）,并制成碳纤维增强树脂复合材料。利用红外光谱（FT-IR）、核磁共振氢谱（¹H NMR）、凝胶渗透色谱（GPC）、旋转流变、差示扫描量热分析（DSC）、热失重分析（TGA）和悬梁臂冲击实验对共聚物及其复合材料的结构和性能进行表征。研究结果表明所合成的共聚物具有优良的耐热性和韧性,硅烷芳炔-硅氧烷芳炔嵌段共聚物在氮气气氛下的T_d5高于513℃,1000℃残留率高于78.9%,硅烷芳炔-硅氧烷芳炔嵌段共聚物/碳纤维复合材料的冲击强度高达（30.92±0.44） kJ·m^-2。     

Preparation of a novel crown ether functionalized ionic liquid［A（benzo15C5）HIM］［(CF3SO2）2N］

通过Williamson反应、Friedel-Crafts酰基化等反应合成了新型冠醚功能化离子液体1-烯丙基-3-（6′-氧代苯并-15-冠-5-己基）咪唑双三氟甲磺酰亚胺（［A（benzo15C5）HIM］［（CF₃SO₂）₂N］）,并以IR、¹H NMR对其结构进行了表征。初步探讨了双酚A（BPA）在多壁碳纳米管-离子液体（MWCNTs-IL）修饰玻碳电极上的电化学行为。