Silica‐Supported Phosphotungstic Acid for Gas Phase Dehydration of Glycerol

Phosphotungstic acid (H₃PW₁₂O₄₀ 6H₂O) was immobilized within a hierarchically structured silica matrix by sol–gel inclusion using polyethylene oxide as a phase separation initiator (one‐pot synthesis). The macropore size of the SiO₂‐HPW composites was controlled by the polymer content. The hierarchically structured catalysts with different HPW loadings were tested against their counterparts with monomodal pore size distribution, applying the dehydration of glycerol as a test reaction. The catalysts with bimodal pore size distribution showed a significantly better long‐term stability. The improved performance was attributed to their balanced acidity, excellent leaching stability, and enhanced mass transfer within the hierarchically structured pore system.     

脱水反应生成2-乙烯基吡啶的研究

研究了以2-羟乙基吡啶经脱水生成2-乙烯基吡啶的方法。采用酸碱两类脱水剂,对其反应效果分析比较,发现碱性脱水剂氢氧化钾,更有利于2-乙烯基吡啶合成;探讨了脱水剂用量、反应温度、反应时间等影响因素,得出了适宜的反应条件：n（2-羟乙基吡啶）：n（氢氧化钾）=5：2,在loo。C温度条件下,反应时间2h,反应收率80．2％,产物纯度可达98．1％,水分低于1％。     

Dehydration of Ethanol into Ethylene over Solid Acid Catalysts

The dehydration of ethanol into ethylene was investigated over various solid acid catalysts, such as zeolites and silica–alumina, at temperatures ranging 453–573 K under atmospheric pressure. Ethylene was produced via diethyl ether during the dehydration process. H-mordenites were the most active for the dehydration. It was suggested that the catalyst activity could be correlated with the number of strong Br?nsted acid sites in the catalyst. Further, the H-mordenite was more stable with a SiO₂/Al₂O₃ ratio of 90 than with a SiO₂/Al₂O₃ ratio of 20.     

活性氧化铝催化异丁醇脱水制异丁烯

在500℃焙烧拟薄水铝石得到Al2O3催化剂(500-Al2O3),采用X射线衍射(XRD)、物理吸附(BET)和NH3程序升温脱附(NH3-TPD)等手段对其进行表征,并在固定床连续微反装置中考察反应条件对500-Al2O3催化异丁醇脱水制异丁烯反应的影响。结果表明:500-Al2O3催化剂具有γ-Al2O3物相,比表面积为275 m2/g,孔径为0.42 cm3/g,酸量为0.541 5 mmol/g3,对异丁醇脱水制备异丁烯具有较好的活性、选择性和稳定性。在反应温度270℃,常压,空速0.21 h-1和载气流量为60 mL/min条件下,异丁醇转化率和异丁烯选择性分别为99.46%和98.76%。     

Dehydration of 1-phenylethanol over solid acidic catalysts

Dehydration of 1-phenylethanol has been carried out over a solid acidic catalyst in order to examine the effect of the concentration of effective acid sites on the reaction rate, styrene selectivity and catalyst fouling. The reaction rate increased with the concentration of effective acid sites, while styrene selectivity decreased. The catalyst deactivation depended upon the concentration of the effective acid sites and also the size of the micro pores in the catalyst. Taking into account the reaction rate and selectivity, ALO-4 alumina was the most suitable catalyst for the present reaction. An activation energy for the dehydration over ALO-4 alumina was 83.8 kJ mol^?1. The dehydration reaction could be a useful tool for the characterization of the nature of the acid sites.     

W03/HZSM-5催化乙醇脱水制乙烯

采用浸渍法制备了一系列WO3负载量不同的改性HZSM-5分子筛催化剂,考察了ω(WO3)和工艺条件对乙醇脱水反应的影响,并用X射线衍射(XRD)、N2吸附-脱附、氨气程序升温脱附(NH3-TPD)等技术对催化剂进行了表征。结果表明：少量WO3的引入不破坏HZSM-5分子筛的骨架结构,但对表面酸量产生了一定的影响;弱酸量...     

过渡金属改性HZSM-5催化剂的乳酸乙酯脱水性能

分别采用FeCl3·6H2O和MnCl2·4H2O对HzsM-5分子筛进行改性,得到Fe-ZSM-5和Mn-ZsM-5催化剂,采用x射线衍射(xRD)和傅立叶红外光谱(FT-IR)对改性前后的样品进行表征,并考察了HZSM-5分子筛改性前后在乳酸乙酯脱水制丙烯酸乙酯反应中的催化性能.结果表明,与HZSM-5相比,改性后的Fe-ZSM-5和Mn-ZSM-5的结晶度下降,硅铝比降低,活性降低,选择性增加,且Mn-ZSM-5的催化性能优于Fe-ZSM-5的催化性能,在180℃下反应3 h,丙烯酸乙酯收率达到14.65%.     

Liquid-phase Dehydration of d-xylose over Microporous and Mesoporous Niobium Silicates

Microporous AM-11 crystalline niobium silicates were studied as solid acid catalysts for the dehydration of xylose in a water-toluene solvent mixture at 140–180 °C. After 6 h at 160 °C, xylose conversions of up to 90% and furfural yields of up to 50% were achieved, and the catalysts could be reused without loss of activity or selectivity. The calcined AM-11 catalysts gave higher furfural yields than HY zeolite and mordenite, under identical reaction conditions. Ordered mesoporous MCM-41-type niobium silicates with Si/Nb molar ratios of either 25 or 50 were also found to be recyclable catalysts for xylose dehydration, and gave furfural yields consistently in the range of 34–39% (after 6 h reaction at 160 °C).     

Zn与Mn复合改性HZSM-5催化低浓度乙醇脱水制乙烯

对浸渍法锌锰复合改性HZSM-5分子筛用于催化低浓度乙醇脱水制备乙烯进行了研究. 探讨了改性溶液类型、HZSM-5原粉硅/铝比和改性条件(改性溶液浓度、浸渍时间、浸渍温度、焙烧温度)对Zn/Mn/ZSM-5催化乙醇脱水效果的影响,通过XRD、孔体积与比表面积、微观形貌分析等方法对改性前后的HZSM-5进行了表征. 结果表明,当HZSM-5原粉硅/铝比为25,改性温度为40℃, Zn(NO3)2和MnCl2浓度分别为2%和6%条件下改性1 h,再于550℃焙烧获得的分子筛催化效果最好,乙醇转化率和乙烯选择性分别达到99%和92%以上. 表征结果表明,Zn2+和Mn2+进入了分子筛骨架中,分子筛能很好地保持原有的结构,并且B酸中心量减少,L酸中心量增多,这有利于乙醇催化脱水制乙烯.     

Acidic and catalytic properties of CsxH3−xPW12O40 heteropolyacid compounds

The heteropolyacid of Keggin structure (H₃PW₁₂O₄₀) and several of its cesium salts have been synthesized and characterized for their acidic properties. Chemical analysis, TGA, NH₃ adsorption-desorption and³¹P MAS-NMR techniques permit the characterization of the Brønsted acidity. The catalytic properties were studied forn-butane isomerization and for methanol conversion to dimethyl ether at 200 and 180°C, respectively. Our conclusion is that, in term of conversion, the more acidic catalysts are in the range Cs_2/2.7 if considering a wide range of acid strengths evidenced by methanol conversion. The range is Cs₂/Cs_2.1 if one considers only very strong acidity as evidenced byn-butane isomerization.     

钨锗酸的催化脱水反应

报道了钨锗酸对醇脱水成醚或成烯的催化反应。     

Investigation of N-(Hydroxylethyl)pyrrolidone Dehydration over REO_x-doped Nano-ZrO_2 Catalyst

1 INTRODUCTION Poly-N-vinyl-pyrrolidone (PVP) is a non-ionic water-soluble chemical, which is widely used in many industrial fields such as pharmaceutical, cosmetic, foodstuff, electronics, printing, paper-making, deter- gent and adhesive etc.[1]. Traditional acetylene process is dangerous because of using acetylene under high temperature and pressure[2] Nowadays, it is usually produced by polymerization of N-vinyl-pyrrolidone (NVP), which is produced by cata- lytic dehydration of N-(h…     

Dehydration reactions and kinetic parameters of gibbsite

Dehydration reactions and the corresponding kinetics of gibbsite [γ-Al(OH)₃] were analyzed using non-isothermal thermoanalysis and the Kissinger equation. It is concluded that the starting temperature of the dehydration reaction of γ-Al(OH)₃ rises with increasing heating rate of the system. At a heating rate of 10 °C min⁻¹, γ-Al(OH)₃ has lost part of its crystalline water, and was completely transformed into boehmite (γ-AlOOH)) at about 317 °C. However, γ-AlOOH did not lose the residual crystalline water entirely, and did not change into amorphous Al₂O₃ until the system was above 700 °C. The kinetic energy needed to convert γ-Al(OH)₃ to γ-AlOOH, and γ-AlOOH to amorphous Al₂O₃, was calculated by differential scanning calorimetry (DSC) with activation energies of 108.50 and 217.24 kJ mol⁻¹, pre-exponential factors of 2.93 × 10⁹ and 8.30 × 10¹³, and reaction orders of 0.96 and 1.06, respectively. The kinetic parameters of dehydration reactions for γ-Al(OH)₃ obtained using the derivative thermogravimetric method (DTG) are very similar to that of obtained by DSC.     

煤层气脱水工艺分析

对国内AW煤层气进行三甘醇法(TEG)脱水工艺模拟分析,可以得出:随着原料煤层气压力增大,脱水率增大,水露点降低,但变化的幅度均逐渐减小;原料气温度则相反,温度升高时,水露点升高和脱水率降低,变化幅度逐渐增大;进料量增大时出现"吹液"而使得脱水效果降低;随贫液温度升高,水露点和脱水率分别呈线性增大和减小,但总体上影响不大;综合考虑制造成本和脱水效果,存在一个最优塔板数,若在此基础上继续提高塔板数意义不大。     

微波加热CoCl2·6H2O的脱水研究

研究了水合氯化钴微波脱水新工艺,与常规热风干燥工艺相比较,微波干燥8min的脱水效果与100℃热风干燥60min的效果相当.     

Hydrogenation of 1,3-butadiene and of crotonaldehyde over highly dispersed Au catalysts

When Au is deposited as nano-particles on select metal oxides, it exhibits surprisingly high catalytic activity for many oxidation reactions. Therefore, there is also the possibility to improve the activities of Au catalysts for hydrogenation using the appropriate preparation methods like the gas-phase grafting method (GG) and the deposition precipitation method (DP). In this work, we investigated the hydrogenation of 1,3-butadiene and of crotonaldehyde over Au catalysts prepared by GG and DP and discussed the structure sensitivity of these reactions. From these experiments, it was found that the catalytic activities for the hydrogenation of 1,3-butadiene over Au catalysts was almost structure insensitive in terms of the size effect of Au particles and the influence of metal oxides supports and the crotonaldehyde hydrogenation over Au catalysts was slightly sensitive to the selection of the support in the view point of the product selectivity.     

利用Thielepape抽提器的脱水反应

通过一个装有固体吸水剂的Thielepape抽提器，对反应共沸物进行循环脱水，可以改进酯化、醚化等脱水反应，此法优于使用分水器的回流法。     

微波用于高粘原油脱水的研究

文章分析了微波破乳的机理,并以脱水率为考查依据,采用正交设计的方法对影响稠油微波脱水的主要因素,即原油含水量、微波辐射时间、微波功率进行了系统研究。结果表明,原油含水量为影响稠油微波脱水的主要因素,含水量越高,脱水率越大。另外,微波辐射时间与辐射功率对脱水率也存在着一定的影响。对于实验所用的稠油,当微波辐射功率为420 W,辐射时间为120 s,原油含水量为80%时,稠油脱水率最高,达到93.88%。     

Preparation and characterization of heteropolyacid/mesoporous carbon catalyst for the vapor-phase 2-propanol conversion reaction

H₃PMo₁₂O₄₀ catalyst was chemically immobilized on the surface modified CMK-3 (SM-CMK-3) support as a charge compensating component, by taking advantage of the overall negative charge of [PMo₁₂O₄₀]³⁻. The supported H₃PMo₁₂O₄₀/SM-CMK-3 catalyst was characterized to have high surface area (≈1000 m²/g) and relatively large pore volume (0.83 cm³/g). The H₃PMo₁₂O₄₀/SM-CMK-3 catalyst was applied to the vapor-phase 2-propanol conversion reaction. The H₃PMo₁₂O₄₀/SM-CMK-3 catalyst exhibited higher 2-propanol conversion than the unsupported H₃PMo₁₂O₄₀ and the impregnated H₃PMo₁₂O₄₀ on CMK-3. Furthermore, the PMo₁₂/SM-CMK-3 catalyst showed the enhanced oxidation activity (acetone formation) and the suppressed acid catalytic activity (propylene formation) compared to the other two catalysts. It is believed that [PMo₁₂O₄₀]³⁻ species were chemically and finely immobilized on the SM-CMK-3 support as charge matching species, and thus, the PMo₁₂/SM-CMK-3 catalyst showed an excellent oxidation activity.     

浅析渗透汽化膜脱水及其应用

渗透汽化作为一种节能、低能耗、绿色环保的新型膜分离技术,正受到世界范围内越来越广泛的关注和研究。文中简述了渗透汽化膜技术的基本原理、工艺流程和传质模型,介绍了影响分离效果的因素及特点;分析渗透汽化技术在有机溶剂脱水、水中脱除有机物以、有机物/有机物的分离以及化学反应中的工业应用情况,并进行经济性分析,最后展望了该技术的应用前景。