二甲醚（DME）的制备及应用

简述了ＤＭＥ的性质及制备方法，重点介绍了ＤＭＥ在合成汽油过程中的中间体作用以及取代液化石油气作民用燃料的可行性。参考文献１７篇。     

助剂Mn对Cu/Al2O3催化剂一氧化碳加氢性能的影响

二甲醚 (ＤｉｍｅｔｈｙｌＥｔｈｅｒ简称ＤＭＥ)是重要的化工原料 ,它可以羰基化制醋酸甲酯、醋酐 ;可作为甲基化试剂用于制药、农药和染料的合成 ,可与苯胺发生烷基化反应生成Ｎ ,Ｎ -二甲基苯胺 ;从二甲醚出发还可以合成乙烯、汽油等。同时 ,二甲醚可以替代部分氯氟卤代烃用作汽溶胶喷射剂和制冷剂 ;高浓度的二甲醚可用作麻醉剂 ;此外 ,二甲醚还可成为城市煤气和液化气的代用品、也可作为汽车燃料。因而 ,二甲醚的生产和应用研究越来越引起人们的关注。最早的二甲醚合成方法是在硫酸作用下的甲醇脱水 ,由于污染大、成本高而被淘汰 ;现在…     

气相色谱法测定液化石油气中二甲醚含量

液化石油气是石油产品之一,是由炼厂气或天然气(包括油田伴生气)加压、降温、液化得到的一种无色、挥发性气体。由炼厂气所得的液化石油气、主要成分为丙烷、丙烯、丁烷、丁烯,同时含有少量戊烷、戊烯。二甲醚又称甲醚(DME),在常压下,是一种无色气体,压缩成液体,具有轻微醚香味。二甲醚易压缩、易贮存、燃烧效率高、污染低,可替代煤气、液化石油气作民用燃料。但由于其对塑料物质有较     

气相色谱法同时测定液化石油气中各组分及二甲醚含量

<正>液化石油气(LPG)按GB 11174-2011《液化石油气》标准分为商品丙烷、商品丁烷和商品丙丁烷混合物。二甲醚又称甲醚,化学式CH3OCH3,无色、易燃、有轻微醚味的气体,毒性较低,爆炸下限比液化石油气高,用于民用燃料时比液化石油气更安全。由于二甲醚比液化石油气每吨便宜2 000~3 000元,在液化石油气中掺入二甲醚,再以液化石油气价格出售赚取高额利润已经成为了行业潜规     

在改性高岭土催化剂上甲醇脱水生成二甲醚的动力学考察

采用积分反应器,考察了常压下在改性高岭土（ＭＫ）催化剂上甲醇脱水生成二甲醚的反应动力学,根据Ｌａｎｇｍｕｉｒ均匀吸附理论,采用Ｒ－Ｅ机理,推断吸附的甲醇分子与气相主体中的甲醇分子发生的表面反应为速率控制步骤（ＲＤＳ）,得到双曲线型动力学方程为：ｒ＝ｋｓｂＭｐＭ＾２／（１＋ｂＭｐＭ＋ｂｐＥ）ｒ为反应速率,ｋｓ为反应速率常数,ｂＭ为甲醇的吸附平衡常数,ｂ为二甲醚和水的吸附平衡常数之和,ｐＭ、ｐＥ分别为     

复合催化剂中H-ZSM-5酸性对合成气制二甲醚的影响

对合成气制二甲醚（ Ｄ Ｍ Ｅ）复合催化剂中脱水组分 Ｈ Ｚ Ｓ Ｍ ５ 分子筛进行水热处理及 Ｎ Ｈ３ Ｔ Ｐ Ｄ、 Ｃ Ｏ２ Ｔ Ｐ Ｄ 表征． 研究结果表明, 在 Ｈ Ｚ Ｓ Ｍ ５ 分子筛脱水组分上具有两种酸性中心,高温 Ｎ Ｈ３ 的脱附峰代表强酸中心, 低温 Ｎ Ｈ３ 的脱附峰代表弱酸中心． 同时, 亦有两种不同强度的碱中心． 随 Ｈ Ｚ Ｓ Ｍ ５ 水热处理温度的提高, 总酸量及强酸中心数量逐渐降低, 碱性中心数目随 Ｈ Ｚ Ｓ Ｍ ５ 水热处理温度的提高略有增加, Ｄ Ｍ Ｅ的选择性随之提高． Ｄ Ｍ Ｅ 主要是在 Ｈ Ｚ Ｓ Ｍ５ 分子筛的弱酸中心上生成． 对 Ｈ Ｚ Ｓ Ｍ５ 于 ６００ ℃处理后与铜基催化剂混合制得的复合催化剂, 对其反应性能考察后发现, 当 Ｈ２／ Ｃ Ｏ≈２ 时, ４～６ Ｍ Ｐａ、２ ０００～３ ０００ ｈ－ １、２６０ ℃为最适宜反应条件． 此时, Ｃ Ｏ 的转化率≥ ９０％ , 对 Ｄ Ｍ Ｅ 和甲醇的选择性为９６％ , Ｄ Ｍ Ｅ 在所有有机产物中的选择性≥ ８０％ , Ｄ Ｍ Ｅ的含量≥ ２０％ ． 提高反应压力, Ｃ Ｏ 的转化率及 Ｄ Ｍ Ｅ 在产物中的含量有较大提高, 但对 Ｄ Ｍ Ｅ的选择性影响不大．     

溶剂甲醇过程的溶剂选择

溶剂甲醇过程的溶剂选择至关重要。本文筛选了三乙二醇二甲醚（ＴＲＩＧＬＹＭＥ）作为溶剂，测定了甲醇在溶剂中的溶解度及活度系数。在本文的研究条件下，甲醇的溶解特性符合亨利定律，以实验数据回归，亨利系数Ｈ＝０．３７４３ｅｘｐ（－３０１３．６／Ｔ）ＭＰａｍ＾３ｍｏｌ＾－１。通过与其他溶剂比较后可以得出：按甲醇在不同溶剂中的溶解度大小排序：ＴＧＩＧＬＹＭＥ〉ＴＥＧＤＭＥ〉Ｓｑｕａｌａｎｅ〉ＶｅｓｔｏｗａｘＳ     

甲醇脱水制二甲醚的杂多酸/纳米HZSM-5复合固体酸催化剂

开发低温、高活性和良好稳定性的催化剂成为甲醇气相脱水制二甲醚乃至合成气一步法制二甲醚反应的核心.在氧化铝挤条成型的纳米HZSM-5沸石上负载Keggin结构12-磷钨酸制备了复合固体酸催化剂, 通过FT-IR、UV-Raman、³¹P MAS-NMR和XRD对所制备的样品进行表征. 以甲醇气相脱水制二甲醚为探针反应的研究结果表明, 在选定的操作条件下连续运转超过300 h, 甲醇摩尔转化率大于87%(理论转化率90.9%), 二甲醚摩尔选择性高于99.0%, 是目前该反应非常有效的催化剂之一.     

浆态床合成气制二甲醚双功能催化剂的性能

在浆态床合成气制二甲醚过程中，在２８０℃，４ＭＰａ、尾气流量４５００ｍＬ／ｇｃａｔ．ｈ条件下，考察了甲醇合成和甲脱水催化剂组成的双功能催化睦合成的影响，随二者质量比的增加，合成气的转化率，二甲醚生成速率逐渐增加，在催化剂比例４－７时达最高值后降低，随催化剂比例的增加，二甲醚、烷烃的选择性逐渐降低，甲醇选择性逐渐升高，当催化剂比例为４－５时二甲醚生成速率最高达１５－１６ｍｍｏｌ／ｇｃａｔ．ｈ，甲醇当     

催化剂分子结构及共聚物配体的交替结构与其催化活性关系的理论研究

采用以ＡＳＥＤ－ＭＯ为基础的结构自动优化的ＥＨＴＯＰＴ法及Ｍｏｎｔｅ－Ｃａｒｌｏ法，对甲醇羰基化制乙酸的催化剂分子结构及共聚物配体的交替结构进行了理论研究。     

浆态床二甲醚合成中V2O5、Sm2O3对脱水组分γ-Al2O3的修饰作用

采用等容浸渍法制备改性脱水催化剂，通过H2-TPR、Pyridine-IR、还原态NH3-TPD、XRD等表征手段，以及目标反应浆态床CO+H2合成二甲醚，研究了催化剂的还原性能以及酸中心分布与反应性能之间的关系。H2-TPR结果表明，在脱水催化剂γ-Al2O3、V2O5/γ-Al2O3和Sm2O3/γ-Al2O3上不出现还原峰，V2O5、Sm2O3的加入改善了复合催化剂中Cu的还原性能，促进了甲醇催化剂的还原。Pyridine-IR表明，V2O5和Sm2O3的加入对L酸、B酸的量影响不大。还原态NH3-TPD说明V2O5和Sm2O3的加入改变了酸中心的分布，增加了弱酸中心的比率。XRD结果发现，V2O5和Sm2O3均匀分散在γ-Al2O3上，没有新的物种生成。二甲醚合成目标反应的结果表明，改性后催化剂的反应活性增强，合成反应中CO转化率、二甲醚的选择性都得到提高。V2O5和Sm2O3的添加增加了弱酸中心数量，促进了脱水活性，从而提高了复合催化剂合成二甲醚的活性和选择性。     

完全液相法Cu-Zn-Si-Al催化剂一步合成二甲醚

采用完全液相法,以廉价的硅溶胶作为硅原料,制备了一系列的Cu-Zn-Si-Al双功能浆状催化剂,考察不同硅铝比对浆态床CO加氢合成二甲醚的影响。 两周的活性评价表明,硅的引入显著提高了催化剂的活性和稳定性。 当n(Si)/n(Al)=2时,CO转化率最高,为58.1%,且二甲醚的选择性为80.2%。 通过FTIR、XRD、TPR、TPD、BET、XPS和TEM等技术手段对催化剂进行了表征,结果表明,硅组分的添加可以促进活性组分Cu物种的分散,并能够改善完全液相法热处理而导致的积碳现象。 且Si组分的引入与催化剂中的Al相互作用,显著提高了催化剂的甲醇脱水性能,从而使催化剂具有较高的二甲醚选择性。     

Dimethylether production on zeolite catalysts activated by Cl-, F- and/or ultrasonication

The chlorinated and fluorinated zeolite catalysts were prepared by the impregnation of zeolites( H-ZSM-5,H-MOR or H-Y) using two halogen precursors( ammonium chloride and ammonium fluoride) in this study. The influence of ultrasonic irradiation was evaluated for optimizing both halogen precursors for production of dimethylether( DME) via methanol dehydration in a fixed bed reactor. The catalysts were characterized by SEM,XRD,BET and NH3-TPD. The reaction conditions were temperatures from 100 to 300 ℃ and a WHSV = 15. 9 h-1. All halogenated catalysts showhigher catalytic activities at all reaction temperatures studied. However, the halogenated zeolite catalysts prepared under ultrasonic irradiation showhigher performance for DME formation. The chlorinated zeolite catalysts show higher activity and selectivity for DME production than the respective fluorinated versions.     

二甲醚水蒸气重整制氢的ZSM-5和Cu-Zn的复合催化体系

二甲醚水蒸气重整制氢反应是燃料电池理想的供氢方式之一.探讨了二甲醚水蒸气重整过程中的反应与反应、反应与传热的耦合协同效应.采用二甲醚水解催化剂ZSM-5(硅铝比为25)和甲醇水蒸气重整催化剂(Cu-Zn系列及商用Cu-Zn-Al催化剂)混合制得二甲醚水蒸气重整的复合催化剂.在固定床反应装置中评价了催化剂活性并对催化剂进行了透射电镜、X射线衍射及N2吸附表征.结果表明,复合催化剂的活性除了受催化剂组成和铜含量的影响外,还与Al和Zr的量有关.在Cu:Zn摩尔比为60:30时,Al和Zr的同时加入使催化剂中Cu晶粒分散最好,催化剂具有较高的低温活性,二甲醚在空速为4 922 ml/(g·h)和260℃下的转化率达到72%.     

Effect of the Si/Al ratio of HZSM-5 zeolite on the production of dimethyl ether before and after ultrasonication

A series of as-synthesized HZSM-5 zeolites with different Si/Al ratios (25, 90, 120, 240 and 400) were post-treated by ultrasonication for an optimum time of 60 min. The morphology, acidity and textural properties of HZSM-5 were characterized with XRD, SEM, N₂ adsorption and NH₃-TPD techniques. The catalytic performance was evaluated by dehydration of methanol to dimethyl ether (DME), which is a promising gaseous automotive fuel in future. It was found that the Si/Al ratio of HZSM-5 had considerable impacts on its catalytic performance for dehydration of methanol to DME. Its activity increased with decreasing Si/Al ratio from 400 to 25. Ultrasonication of HZSM-5 could significantly improve its catalytic performance.     

The direct synthesis of dimethyl ether from syngas over hybrid catalysts with sulfate-modified γ-alumina as methanol dehydration components

A series of γ-Al₂O₃ samples modified with various contents of sulfate (0–15 wt.%) and calcined at different temperatures (350–750 °C) were prepared by an impregnation method and physically admixed with CuO–ZnO–Al₂O₃ methanol synthesis catalyst to form hybrid catalysts. The direct synthesis of dimethyl ether (DME) from syngas was carried out over the prepared hybrid catalysts under pressurized fixed-bed continuous flow conditions. The results revealed that the catalytic activity of SO₄²⁻/γ-Al₂O₃ for methanol dehydration increased significantly when the content of sulfate increased to 10 wt.%, resulting in the increase in both DME selectivity and CO conversion. However, when the content of sulfate of SO₄²⁻/γ-Al₂O₃ was further increased to 15 wt.%, the activity for methanol dehydration was increased, and the selectivity for DME decreased slightly as reflected in the increased formation of byproducts like hydrocarbons and CO₂. On the other hand, when the calcination temperature of SO₄²⁻/γ-Al₂O₃ increased from 350 °C to 550 °C, both the CO conversion and the DME selectivity increased gradually, accompanied with the decreased formation of CO₂. Nevertheless, a further increase in calcination temperature to 750 °C remarkably decreased the catalytic activity of SO₄²⁻/γ-Al₂O₃ for methanol dehydration, resulting in the significant decline in both DME selectivity and CO conversion. The hybrid catalyst containing the SO₄²⁻/γ-Al₂O₃ with 10 wt.% sulfate and calcined at 550 °C exhibited the highest selectivity and yield for the synthesis of DME.     

Kinetic modeling for the conversion of synthesis gas to dimethyl ether on a mixed Cu-ZnO-Al<Subscript>2</Subscript>O<Subscript>3</Subscript> catalyst with γ-Al<Subscript>2</Subscript>O<Subscript>3</Subscript>

A model is proposed for the kinetics of the direct conversion of synthesis gas to dimethyl ether (DME) on a bifunctional catalyst in a flow reactor. Calculations for the yield of methanol and DME were carried out using literature data for the kinetics of methanol synthesis and methanol dehydration.     

浆态床用CuO/ZrO2催化剂的完全液相法合成及其对CO加氢的催化性能

 利用完全液相法制备了CuO/ZrO2浆状催化剂,通过X射线衍射、氮气吸附和程序升温还原等方法对催化剂的结构和织构性质进行了研究,并考察了CuO/ZrO2催化剂上CO加氢反应的性能. 结果表明,本方法制备的CuO/ZrO2浆状催化剂具有与传统方法制备的固体催化剂相似的相结构; 利用共沸蒸馏法进行表面处理后, CuO/ZrO2催化剂分散均匀且易于还原; CuO/ZrO2浆状催化剂用于CO加氢反应时,不需另外添加甲醇脱水剂就可以直接合成二甲醚,在473 K时CuO/ZrO2对二甲醚的选择性达到92.1%, 并且在15 d的反应中催化剂呈现出良好的稳定性.     

Methanol conversion to DME as a blue fuel:The beneficial use of ultrasonic irradiation for the preparation of CuO/H-MOR nanocatalyst

Methanol conversion to DME was investigated over CuO /H-MOR nanocatalyst prepared by precipitation and /or by precipitation flowed by ultrasonic irradiation methods. BET,XRD,SEM,NH3-TPD and H2-TPR techniques were used to characterize nanocatalysts. The effective ultrasonication factors encountered during carrying out the dehydration of methanol on Cuo /H-MOR zeolite catalysts to produce dimethylether are studied in the present work. These factors include: the type of ultrasonication media,the ultrasonication time,and the fixed weight of the solid catalyst per the volume of the ultrasonication liquid media( Wcatalyst/ Vliquidratio). XRD showed that structure of H-MOR is not damaged even after it is loaded with CuO nanoparticles or with ultrasonication. H2-TPR profiles indicated that reducibility of sonicated CuO / H-MOR nanocatalyst is higher than non-sonicated catalyst. It is found that employing ultrasound energy for 60 min has the highest influence on the surface properties of nanocatalyst and its catalytic performance( activity and stability) of CuO / H-MOR catalyst. Surface morphology( SEM) of the sonicated CuO /H-MOR catalysts have clarified that methanol by itself used as an ultrasonication medium gives the best results concerning the homogeneity of particle sizes compared to the non-sonicated catalyst,where large agglomerates and non-homogeneous clusters appeared. Water used as a sonication medium showed many large agglomerates in addition to some smaller particles resulted in lowcatalytic activity. The different alcohols and( Wcatalyst/ Vliquid) ratio were examined to give precise correlation with the catalytic activity of the sonicated CuO / H-MOR zeolite catalyst. These findings certified that ultrasonication has a deep effect on the surface morphology and hence on the catalytic behavior of the dehydration of methanol to DME. NH3-TPD shows that ultrasound irradiation has enhanced the acidity of CuO / H-MOR catalyst and hence it’s catalytic performance for DME formation.     

Production of dimethylether(DME) as a clean fuel using sonochemically prepared CuO and /or ZnO- modified γ- alumina catalysts

The catalytic conversion of methanol to dimethylether(DME)was studied over CuO/Al2O3,ZnO/Al2O3and ZnOCuO/Al2O3nanocatalysts prepared in presence or absence of ultrasonic irradiation.The catalysts were characterized by X-ray diffraction(XRD),surface characterization method(BET),scanning electron microscope(SEM),H2-temperature programmed reduction(H2-TPR)and temperature programmed desorption of ammonia(NH3-TPD).The experimental results show that during catalytic dehydration of methanol to dimethylether,the activities of the CuO/Al2O3,ZnO/Al2O3and ZnO-CuO/Al2O3catalysts prepared using ultrasonic treatment are much higher than those prepared in absence of ultrasonication.SEM shows that the use of ultrasonication results in much smaller nanoparticles.BET and XRD show that the ultrasonication increases the surface area and pore volume of the catalysts.H2-TPR profiles indicated that reducibility of the sonicated nanocatalysts is carried out at lower temperatures.NH3-TPD shows that ultrasound irradiation has enhanced the acidity of the nanocatalyst and hence enhanced catalytic performance for DME formation.