NaX沸石的改性及与乙醇缩合反应性的关联

ＮａＸ沸石的改性及与乙醇缩合反应性的关联徐斌，杨春，孟中岳（南京师范大学化学系，南京２１００２４）关键词乙醇缩合，碱性催化，ＮａＸ沸石，改性沸石分子筛的碱性质和碱催化反应的研究是近年来沸石催化中一个引人注目的课题［１－７］．碱性沸石催化乙醇缩合是制备...     

沸石的碱性催化:乙醇双分子缩合反应

本文首次发现在碱性沸石上乙醇参数发生以正丁醇为主产物的双分子缩合反应。在所研究的催化剂中, 含铷的LiX沸石表现出最高的反应选择性。研究表明, 这一碱化反应的活性与催化剂的酸碱性质密切相关。催化剂的碱性对反应起决定作用,但催化剂的碱性太强则不利于反应。     

锂／沸石电池的电化学行为

研究了沸石作为常温非水锂电池阴极材料的放电性能和循环特性。通过库仑滴定，三角波电位扫描，Ｘ－射线分析和红外光谱研究了锂／沸石电池的阴极反应机理，发现在ｘ＜３、４ｍｏｌ时，阴极上发生的是锂的嵌入反应。测得锂嵌入ＮａＡ型沸石生成ＬｉＮａＡ的嵌入自由能为－２３１ｋＪ／ｍｏｌ（２５℃）。用电化学方法测得，常温下锂在ＬｉｘＮａＡ（ｘ＝０．１７～０．６９）中的化学扩散系数为１×１０－９～１×１０－１０ｃｍ２／ｓ数量级。     

沸石催化剂上醇的醚化反应

研究了乙醇，正丁醇，仲丁醇和正戊醇有ＺＳＭ－５和Ｂｅｔａ沸石上的醚化反应。用ＮＨ３－ＴＰＤ和ＩＲ测定了ＺＳＭ－５沸石的表面酸性，讨论了沸石表面Ｂ酸和Ｌ酸和与醚化活性的关系。结果表明，乙醇的脱水反应既可以在Ｂ酸中心上进行，也可以在Ｌ酸中心中心上进行，既可以在强酸中心上进行，亦可以在弱酸中心上进行。     

TS—1沸石的合成,结构及催化性能探讨

讨论了用两种不同硅源合成钛硅沸石ＴＳ－１的方法和合成过程中应注意的问题，并通过ＸＲＤ、ＩＲ、ＴＥＭ和ＳＳＡ等手段对沸石的结构及热稳定性进行了表征和研究，确认了钛已进入沸石骨架，初步探讨了ＴＳ－１沸石合成时ＴＰＡ离子的模板作用机理，此外，通过在温和条件下用Ｈ２Ｏ２选择性氧化正己烷的反应，考察了ＴＳ－１沸石的催化活性，得到了比较满意的结果。     

甲苯甲醇侧链烷基化反应中沸石催化剂酸碱中心的作用Ⅰ．改性的X型、X／ZSM－5型和KX型沸石催化剂

甲苯甲醇侧链烷基化反应中沸石催化剂酸碱中心的作用Ⅰ．改性的Ｘ型、Ｘ／ＺＳＭ－５型和ＫＸ型沸石催化剂李永光，畅晋英，王建平（太原工业大学化工系，太原０３００２４）关链词沸石，侧链烷基化，甲苯，甲醇甲苯甲醇烷基化反应有两种方式：在苯环上烷基化生成二甲苯；...     

改性丝光沸石上甲醇胺化的研究——水汽处理对沸石性能的影响

采用哟饱和中毒，ＮＨ３－ＴＰＤ、静态吸附、ＩＲ、ＸＲＤ和分子探针反应等方法，研究了用于甲醇胺化反应的改性丝光沸石催化剂性质，结果发现，丝光沸石水汽处理脱吕后的孔道结构基本不变，晶胞的收缩和非骨架铝在孔道内的沉积，不足以严重限制甲醇胺化产物三甲胺在孔道内的进出；且在改性后，由于非骨架非孔道内的沉积，分子筛内表面的微环境发生了变化，致使有些活性位不利于三 的吸附和生成，从而有利于进一步提高目的产物二甲     

β沸石骨架外阳离子分布

运用结构化学理论和多晶Ｘ射线用射技术，确定了β沸石骨外阳离子的位置，这些阳离子随机地分布在β沸石层错结构中６套不同的结晶位置上，都处于三维通道内造近六元环，并与６个骨架氧配位，从其几何环境和配位情况来看，β－沸石骨架外阳离子位置仅为一种类型，在Ｈβ沸石中，相应的质子酸中心也只有一种类型，此结论在ＮＨ３－ＴＰＤ实验中得到证实，处于如何位置的阳郭子和对应的酸中心易与反应物分子接触，据此推测Ｈβ沸石将是     

杂原子B—ZSM—35沸石的干法合成,表征及CO＋H2反应性能的研究

首次利用吸附态模板剂在Ｎａ２Ｏ－ＳｉＯ２－Ｂ２Ｏ３－ＤＥＡ干粉体系中合成了杂原子Ｂ－ＳＺＭ－３５沸石，ＸＲＤ，ＳＥＭ，ＩＲ，及ＣＯ加氢反应研究了其物理化学特性。结果表明，Ｂ原子同晶取代Ａｌ原子进入ＺＳＭ－３５沸石骨加。     

β沸石在丙烯醚化反应中的催化性能

研究了β沸石在不同焙烧温度和加入粘合剂条件下对丙烯与异丙醇合成异丙醚的催化性能。并通过ＸＲＤ、ＸＰＳ、ＮＨ３－ＴＰＤ、ＦＴ－ＩＲ及化学吸附等手段表征了β沸石的物理化学性质。结果表明：焙烧对丙烯醚化反应存在一合适的温度范围；Ａｌ２Ｏ３粘合剂提高了丙烯转化率，降低了异丙醇脱水活性；粘合剂使沸石表面上Ｌ酸中心的比例增加；丙烯醚化反应与Ｌ酸中心存在较好的对应关系，而异丙醇脱水反应与Ｂ酸中心对应；高温焙烧β沸石使骨架铝向表面迁移，粘合剂Ａｌ２Ｏ３能抑制沸石的晶胞收缩。     

Catalyst activity comparison of alcohols over zeolites

Alcohol transformation to transportation fuel-range hydrocarbon over HZSM-5 (SiO₂/Al₂O₃ = 30) catalyst was studied at 360 °C and 300 psig. Product distributions and catalyst life were compared between methanol, ethanol, 1-propanol and 1-butanol as a feed. The catalyst life for 1-propanol and 1-butanol was more than double compared with that for methanol and ethanol. For all the alcohols studied, the product distributions (classified to paraffin, olefin, naphthene, aromatic and naphthalene compounds) varied with time on stream (TOS). At 24 h TOS, liquid product from 1-propanol and 1-butanol transformation primarily contains higher olefin compounds. The alcohol transformation process to higher hydrocarbon involves a complex set of reaction pathways such as dehydration, oligomerization, dehydrocyclization and hydrogenation. Compared with ethylene generated from methanol and ethanol, oligomerization of propylene and butylene has a lower activation energy and can readily take place on weaker acidic sites. On the other hand, dehydrocyclization of the oligomerized products of propylene and butylene to form the cyclic compounds requires the sites with stronger acid strength. Combination of the above mentioned reasons are the primary reasons for olefin rich product generated in the later stage of the time on stream and for the extended catalyst life time for 1-propanol and 1-butanol compared with methanol and ethanol conversion over HZSM-5.     

Synthesis of alkyl glycosides from cyclodextrin using cyclodextrin glycosyltransferase from Paenibacillus sp. RB01

Alkyl glycosides have potential use as biodegradable detergents due to their high surface activity with low toxicity. Recent progress in the application of enzymes to the preparation of these surface-active compounds demonstrates the advantages to the chemical synthesis. In this work, alkyl glycosides were, for the first time, synthesized from cyclodextrin (CD) and various soluble alcohols by transglycosylation reaction using cyclodextrin glycosyltransferase (CGTase) from Paenibacillus sp. RB01. Several alcohols (methanol, ethanol, 1-propanol, 2-propanol, 1-butanol and 2-butanol) as glycosyl-acceptor substrates were evaluated. It was found that the reaction products which were analyzed by TLC were maximum for 30% methanol, 20?C30% ethanol, 10?C20% 1-propanol, 10% 2-propanol, 8% 1-butanol and 5?C10% 2-butanol. In addition, the increase in the yield of alkyl glycoside formation was achieved by using methanol as an acceptor. Optimal reaction conditions for methyl glycoside synthesis from CD were to incubate 1.2% (w/v) ??-CD and 240 U/mL of CGTase in a water/methanol system containing 30% (v/v) methanol, pH 6.0 and a temperature of 40???C. At least three main methyl glycoside products were formed having 1?C3 monosaccharide units attached to methanol which were in accordance with the results of MS analysis.     

Production of methyl ester fuel from microalgae

Microalgae are unique photosynthetic organisms that are known to accumulate storage lipids in large quantitites and thrive in saline waters. Before these storage lipids can be used, they must be extracted from the microalgae and converted into usable fuel. Transesterification of lipids produces fatty acid methyl esters that can be used as a diesel fuel substitute. Three solvents, 1-butanol, ethanol, and hexane/2-propanol, were evaluated for extraction efficiency of microalgal lipids. Type of catalyst, concentration of catalyst, time of reaction, temperature of reaction, and quality of lipid were examined as variables for transesterification. The most efficient solvent of the three for extraction was 1-butanol (90% efficiency), followed by hexane/2-propanol and ethanol. Optimal yield of fatty acid methyl esters was obtained using 0.6N hydrochloric acid in methanol for 0.1 h at 70°C.     

Adsorptive separations for the recovery and purification of biobutanol

A?conceptual adsorption process for the recovery and purification of biobutanol is proposed. Different porous materials are tested on their ability to perform the adsorptive separations relevant to the process. The metal-organic framework ZIF-8, silicalite zeolite and active carbon were compared with respect to their adsorption capacity of 1-butanol dissolved in water, as obtained in static and dynamic conditions by respectively batch and breakthrough measurements at room temperature. Batch experimentation showed that other compounds present in a real ABE fermentation have no significant effect on the adsorption of 1-butanol on ZIF-8. The breakthrough separation of 1-butanol from an aqueous ABE mixture was performed with a ZIF-8 packed column. The desorption of 1-butanol from a saturated ZIF-8 packed column by a stepwise increase of the temperature to 423?K in combination with a purge of a nitrogen gas (60?ml/min) shows that 1-butanol desorbs at low temperature from ZIF-8. Adsorption isotherms of ethanol, 1-butanol and water in liquid phase on the zeolite SAPO-34 were determined by batch adsorption at 298?K. Also the separation of an ethanol/1-butanol mixture and the removal of ethanol from 1-butanol could be achieved with a SAPO-34 packed column. From this experimental work, two materials—ZIF-8 and SAPO-34—thus emerged as suitable adsorbents for the recovery and purification of biobutanol by adsorption.     

Higher-alcohols biorefinery

The concept of a biorefinery for higher-alcohol production is to integrate ethanol and methanol formation via fermentation and biomass gasification, respectively, with, conversion of these simple alcohol intermediates into higher alcohols via the Guerbet reaction. 1-Butanol results from the selfcondensation of ethanol in this multistep reaction occurring on a single catalytic bed. Combining methanol with ethanol gives a mixture of propanol, isobutanol, and 2-methyl-1-butanol. All of these higher alcohols are usefulas solvents, chemical intermediates, and fuel additives and, consequently, have higher market values than the simple alcohol intermediates. Several new catalysts for the condensation of ethanol and alcohol mixtures to higher alcohols were designed and tested under a variety of conditions. Reactions of methanol ethanol mixtures gave as high as 100% conversion of the ethanol to form high yields of isobutanol with smaller amounts of 1-propanol, the amounts in the mixture depending on the starting mixture. The most successful catalysts are multifunctional with basic and hydrogen transfer components.     

Determination of major compounds in sweet wines by headspace solid-phase microextraction and gas chromatography

Headspace solid-phase microextraction (HS-SPME) was studied by high resolution gas chromatographic analysis of major compounds (ethyl acetate, methanol, 1-butanol, 2-butanol, 1-propanol, isobutanol, 2-methyl-1-butanol and 3-methyl-1-butanol) in sweet wines. Five different SPME fibres were tested and the influence of different factors such as temperature and time of desorption, extraction time, stirring, sample and vial volume, sugar and ethanol content were studied and optimized using model solutions. The SPME method was validated with the direct injection method. The proposed HS-SPME-GC method is an appropriate technique for the quantitative analysis of the mentioned analytes in real sweet wines.     

有机相中脂肪酶催化有机硅醇转酯反应机理

首次探讨了皱摺假丝酵母脂肪酶CRL催化有机硅醇及其碳结构类似物与脂肪酸酯的转酯反应机理。结果表明,反应符合乒乓机制,底物中硅原子的存在并未改变脂肪酶催化转酯反应的机制。给出了CRL催化1-三甲基硅烷基乙醇及其碳结构类似物3,3-二甲基-2-丁醇与丁酸正戊酯间的转酯反应动力学方程。     

Copper-Mediated Acetylation of Alcohols by 2-Nitropropane in the Presence of Dioxygen

This work describes the preliminary study of the oxygenation reaction of 2-nitropropane and the acetylation of alcohols by 2-nitropropane in the presence of O₂ mediated by metallic copper or Cu(tmeda)(NO₂ )2 (tmeda = N,N,N',N'-tetramethylethylenediamine). The oxygenolysis was performed in alcoholic solvents (methanol, ethanol, 2-propanol, 1-butanol, 2-butanol) under dioxygen pressure (1 atm) at 50 °C and was followed by Glc. The results show that the formation of acetone is the main reaction and the corresponding esters are formed only in a maximum of 30% yield.     

The chain formation of aldehydes in the radiolytic oxidation of aliphatic alcohols

The effect of dose rate on the yields of aldehyde, hydrogen peroxide and hydrogen in oxygen-saturated methanol, ethanol, 1-propanol, 2-propanol and 1-butanol was studied. A reaction mechanism to explain the results is proposed and discussed. It is concluded that the viscosities of the various alcohols play an important role in determining the length of the chain reactions.