Hydrogen generation from steam reforming of ethanol in dielectric barrier discharge

Dielectric barrier discharge (DBD) was used for the generation of hydrogen from ethanol reforming. Effects of reaction conditions, such as vaporization temperature, ethanol flow rate, water/ethanol ratio, and addition of oxygen, on the ethanol conversion and hydrogen yield, were studied. The results showed that the increase of ethanol flow rate decreased ethanol conversion and hydrogen yield, and high water/ethanol ratio and addition of oxygen were advantageous. Ethanol conversion and hydrogen yield increased with the vaporization room temperature up to the maximum at first, and then decreased slightly. The maximum hydrogen yield of 31.8% was obtained at an ethanol conversion of 88.4% under the optimum operation conditions of vaporization room temperature of 120 ?C, ethanol flux of 0.18 mL/min, water/ethanol ratio of 7.7 and oxygen volume concentration of 13.3%.     

微波诱导甲烷在活性炭/碳化硅上直接转化制C2烃

 在高功率脉冲微波辐照下甲烷可在常压条件下在活性炭/碳化硅和活性炭碳化硅等 三种催化剂上直接转化为C2烃。研究结果表明,当使用合适的微波作用条件时,微波加热与微波 等离子协同作用可使甲烷在多孔碳化硅担载的活性炭催化剂上以很高的转化率和选择性直接转化为乙炔,除单独的微波加热诱导作用和微波等离子催化作用外,转移反应机制可能是微波加热与微波等离子交互作用的具体表现形式,对促进甲烷向乙炔直接转化起了重要作用。     

Cu/SBA-15-SO3H催化木糖一锅转化制备糠醇（英文）

糠醇是一种重要的高附加值化学品,目前工业上由含半纤维素或木聚糖的生物质原料经过酸脱水先制备糠醛,糠醛再进一步加氢制备糠醇.在实际生产中,这两步反应分别在不同的设备中进行,增加了分离纯化和运输成本;目前也很少有研究偶联这两步反应.本工作中,我们制备了一种多功能介孔Cu/SBA-15-SO3H催化剂用于一锅法一步转化木糖到糠醛,并且通过X射线粉末衍射(XRD)、透射电子显微镜(TEM)、傅里叶变换红外光谱(FT-IR)、热重分析(TGA)、电感耦合等离子体发射光谱(ICP-OES)、X射线荧光(XRF)、NH3-程序升温脱附(NH3-TPD)和N2物理吸附等表征检测了负载的酸和金属位点的可用性以及催化剂的物理化学性质,优化了反应温度、氢气压力、反应时间和溶剂体系等反应条件,研究了酸和金属位点的比例以及介孔尺寸对合成糠醇的影响.XRD表征和TEM及HRTEM图像均表明,在负载了磺酸和Cu之后,均会一定程度上破坏SBA-15的形貌,但是依然可以保持原本的有序介孔结构.XPS表明还原后的Cu主要以+1价的形式存在,也有少量的0价和+2价.红外光谱表明磺酸基团和SBA-15载体以共价键形式紧密结合.氮气吸脱附和相关的BET和BJH计算表明,我们的原位制备方法相比于传统浸渍法,磺酸位点的含量提高了7倍以上.通过对反应条件的优化,该体系在140℃和4MPaH2下可以实现62.6%的糠醇收率.过高的温度会引起产物过度加氢生成2-甲基呋喃,而过高的压力会导致原料过度加氢生成木糖醇.合适的溶剂也是反应的关键因素,使用1:3的水/丁醇双相体系,一方面可以有效促进糖的溶解,另一方面可以有效萃取产物,保证了反应的碳平衡.在对催化剂的筛选中发现,单独的SBA-15几乎无催化活性,Cu/SBA-15主要催化木糖加氢生成木糖醇,SBA-15-SO3H主要催化木糖脱水生成糠醛,而物理混合的Cu/SBA-15和SBA-15-SO3H的效率远不如双功能Cu/SBA-15-SO3H催化剂.通过调节磺酸含量和探究产物时间曲线发现,提高酸性位点可以促进木糖转化,但是过多的酸性位点会导致结焦,降低糠醇收率.共同存在的磺酸酸性位点和铜金属位点保持平衡,协同催化串联反应进行.通过调节SBA-15的孔道结构发现,4 nm的孔道最适合反应进行,孔道过大会降低反应的整体碳收率和糠醇收率.本催化体系实现了从木糖一锅多步法制糠醇,并对催化剂的构效关系进行了研究,对反应条件进行了系统的优化,有希望实际应用到糠醇生产中.     

膜催化研究 I: 在钯/陶瓷复合膜反应器中催化甲醇直接脱氢制甲醛

本文用化学镀方法制备了对氢具有高选择性和高透过率的钯/陶瓷复合膜, 并将此复合膜装于特制的膜反应器中, 考察了该反应器对甲醇催化脱氢制甲醛反应的促进作用。作为对比, 在常规反应器中也进行了上述反应。发现在623～773K温度范围内, 甲醇的转化率和甲醛的产率均有很大的提高。在低原料空速下(反应进程为热力学平均控制), 产物甲醛的产率可提高20%以上; 在中等原料空速下(反应进程为动力学控制), 甲醛的产率可提高10～15%。     

Reversible solid-state structural conversion between a three-dimensional network and a one-dimensional chain of Cu(II) triazole coordination polymers in acidic/basic-suspensions or vapors

New Cu(II) triazole coordination polymers with a 3D network were synthesized and reversible structural conversion between a 3D network and a 1D chain with color change was realized by pH controlled acidic and basic-suspensions or vapors. For each conversion process of decreasing and increasing pH, conversion was accomplished with high yield, in which the crystal before conversion played the role of a solid-state crystal template.     

Hβ分子筛催化甜高粱秆汁转化制呋喃类化合物

以γ-丁内酯为溶剂,研究了Hβ分子筛催化富含蔗糖、葡萄糖和果糖的甜高粱秆汁转化制呋喃类化合物（5-羟甲基糠醛或糠醛）的性能。结果表明,甜高粱秆汁在Hβ分子筛上主要转化为5-羟甲基糠醛,而含糖量相同的模型甜高粱秆汁在相同的反应条件下,主要产物却是糠醛。²⁷Al 固体核磁结果表明,甜高粱秆汁中的微量碱性金属钾等能与Hβ分子筛发生离子交换,导致Hβ分子筛上六配位铝转变为四配位铝;因为六碳糖生成糠醛需要Hβ分子筛上具备合适的铝配位环境,而离子交换引起铝配位状态的变化,导致了甜高粱秆汁在Hβ分子筛上的主要产物是5-羟甲基糠醛。     

L'acide hydroxylamine-O-sulfonique,réactif de choix pour la conversion d'aldéhydes en nitriles

Hydroxylamine-O-sulfonic acid: a convenient reagent for the conversion of aldehydes into nitriles . Hydroxylamine-O-sulfonic acid (HAS) proved to be an excellent reagent for the conversion of aliphatic, aromatic and heteroatomic aldehydes into nitriles. There, aldehydes in the form of suspension in HAS water solution, react rapidely to give the corresponding nitriles in high yield. Only with formylpyridines could the intermediate oxime-O-sulfonic acids be isolated.     

Direct catalytic conversion of furfural to 1,5-pentanediol by hydrogenolysis of the furan ring under mild conditions over Pt/Co2AlO4 catalyst

A new strategy was developed for the direct conversion of furfural to 1,5-pentanediol by the hydrogenolysis of the furan ring under mild conditions based on Pt/Co(2)AlO(4) catalyst. This is the first report of the direct catalytic conversion of furfural to 1,5-pentanediol with high yield.     

An improved and efficient synthesis of 2-substituted 1,4-dihydropyridine derivatives via regiospecific bromination

A highly regioselective conversion of DHP to DHP has been achieved for the first time in high yield. Treatment of the bromide with different nucleophiles under basic conditions produced 2-substituted 1,4-dihydropyridines in high yields and purity.     

Effective oxidation of 1,2-cyclooctene by oxo-vanadium(IV) tetradentate Schiff base complexes under 1 atmosphere of molecular oxygen

Development of methods for the understanding of chemical reactivity of high-valent metal-oxo species with respect to organic substrates is important. Here we report a high yield, high TON conversion of cyclooctene using VO (Schiff base) complexes (Figure 1) as catalyst and O₂ as oxidant in MeCN under mild conditions. The results show that catalytic activity increases with a decrease in the number of electron-donating groups. At higher concentration of catalyst and shorter reaction time, a low yield but high selectivity of epoxide was observed.     

在Li-Nd-Zn-Mg氧化物上甲烷氧化偶联

天然气资源丰富,其中主要成分为甲烷.以甲烷为原料开发化工产品一直引起人们的重视.1982年Keller首先提出甲烷氧化偶联制乙烯、乙烷的催化过程,为开拓廉价乙烯原料路线提供了新的可能途径,从而引起各国催化工作者的重视.近年来,此催化过程的乙烯及乙烷的收率(y_(02))已提高到10—30%之间.各国都在努力开发活性高及选择性好的催化剂,促使此催化过程工业化。本文研究了Li-Nd-Zn-Mg氧化物甲烷氧化偶联催化剂,对反应条件进行了初步考察,乙烯及乙烷的收率y_(02)达到30.8%。     

Natural gas pyrolysis in double-walled reactor tubes using thermal plasma or concentrated solar radiation as external heating source

The thermal pyrolysis of natural gas as a clean hydrogen production route is examined.The concept of a double-walled reactor tube is proposed and implemented.Preliminary experiments using an external plasma heating source are carded out to validate this concept.The results point out the efficient CH4 dissociation above 1850 K (CH4 conversion over 90%) and the key influence of the gas residence time.Simulations are performed to predict the conversion rate of CH4 at the reactor outlet,and are consistent with experimental tendencies.A solar reactor prototype featuring four independent double-walled tubes is then developed.The heat in high temperature process required for the endothermic reaction of natural gas pyrolysis is supplied by concentrated solar energy.The tubes are heated uniformly by radiation using the blackbody effect of a cavity-receiver absorbing the concentrated solar irradiation through a quartz window.The gas composition at the reactor outlet,the chemical conversion of CH4,and the yield to H2 are determined with respect to reaction temperature,inlet gas flow-rates,and feed gas composition.The longer the gas residence time,the higher the CH4 conversion and H2 yield,whereas the lower the amount of acetylene.A CH4 conversion of 99% and H2 yield of about 85% are measured at 1880 K with 30% CH4 in the feed gas (6 L/min injected and residence time of 18 ms).A temperature increase from 1870 K to 1970 K does not improve the H2 yield.     

Rapid and Direct Conversion of Graphite Crystals into High‐Yielding,Good‐Quality Graphene by Supercritical Fluid Exfoliation

Graphene has attracted a great deal of attention in recent years due to its unusual electronic, mechanical, and thermal properties. Exploiting graphene properties in a variety of applications requires a chemical approach for the large‐scale production of high‐quality, processable graphene sheets (GS), which has remained an unanswered challenge. Herein, we report a rapid one‐pot supercritical fluid (SCF) exfoliation process for the production of high‐quality, large‐scale, and processable graphene for technological applications. Direct high‐yield conversion of graphite crystals to GS is possible under SCF conditions because of the high diffusivity and solvating power of SCFs, such as ethanol, N‐methyl‐pyrrolidone (NMP), and DMF. For the first time, we report a one‐pot direct conversion of graphite crystals to a high yield of graphene sheets in which about 90–95 % of the exfoliated sheets are <8 layers with approximately 6–10 % monolayers and the remaining 5–10 % are ≥10 layers.     

Synthesis of α-Alkoxylidene Lactones

The α-formylation of α-lactones and the high yield conversion into their respective α-alkoxylidene lactones are described     

Development of predictive tools for optimizing organic reactions

Although microwave chemistry and its applications have undergone rapid growth over the last decade, the technology is not yet employed routinely in all synthetic laboratories. A significant obstacle to implementation concerns the empirical work required to adapt established conditions into alternatives employing higher temperatures. We now have established predictive tools to translate reaction conditions from conventional heated (ambient pressure) to elevated temperature (ambient or elevated pressure). We have studied 45 reactions (including published literature examples) and made in excess of 200 estimations for specific yield or conversion, with a high degree of accuracy. Linear regression analysis of estimated vs. experimental conversion or yield was 0.90 (first iteration) and 0.98 (second iteration).     

Aluminum hydrogen sulfate [Al(HSO4)3] as an efficient catalyst for the preparation of thioacetals

Aluminum hydrogen sulfate, as a heterogeneous solid acid catalyst, has been used for the mild conversion of carbonyl compounds to their thioacetals using 1,2- and 1,3-dithiol under ambient conditions with short reaction times in high to excellent yield in acetonitrile as solvent.     

Chemistry of insect antifeedants from azadirachta indica (part 1): Conversion from the azadirachtin to the azadirachtinin skeletons

The conversion of azadirachtin derivatives to the corresponding azadirachtinin skeletons can be achieved in high yield under mild conditions.     

The high yield and regioselective conversion of an unactivated aziridine to an oxazolidinone using carbon dioxide with ammonium iodide as the catalyst

The conversion of an unactivated 2-alkylaziridine to the corresponding oxazolidinone generally requires a very high pressure of carbon dioxide, a high temperature, an expensive catalyst, and/or a long reaction time. Here, a new, high yield (over 95%), and highly regioselective (over 95%) conversion of an unactivated aziridine to an oxazolidinone is reported. This reaction is easy to perform because it requires a low pressure of carbon dioxide, low temperature, no co-solvent, and the catalyst is the salt ammonium iodide.     

Prolinium Chlorochromate as a New Mild and Efficient Oxidant for Alcohols

Prolinium chlorochromate was prepared by an easy procedure and applied on a silica gel. The reagent was stable and was successfully used for conversion of benzyl and nonbenzyl alcohols into the corresponding carbonyl compounds under mild conditions and in high yield (90-98%).     

Direct preparation of polyfunctional amino-substituted arylmagnesium reagents via an iodine-magnesium exchange reaction

The successive addition of PhMgCl and i-PrMgCl to functionalised iodoanilines allows their conversion to the corresponding amino-functionalised Grignard reagents, which react smoothly with a range of electrophiles in high yield.