Highly cross-linked cationic polymer microspheres as an efficient catalyst for facile CO2 fixation

In this study, a new type of highly cross-linked cationic polymer microspheres was synthesized by a simple procedure of combining 1,2,4,5-tetrakis(bromomethyl)benzene and 4,4′-bipyridine. The influence of solvent used on the material structure and morphology was investigated and the obtained cationic polymers were fully characterized by FT-IR, BET, SEM, EDS, and TGA. Catalytic tests in the synthesis of cyclic carbonate from carbon dioxide (CO₂) and epoxides under mild conditions, along with comparisons to various counterparts, well demonstrate that the newly designed cross-linked cationic polymer with regular spherical structure exhibits high activity and selectivity, coupled with easy recovery and steadily reuse.     

Highly efficient and recyclable ruthenium nanoparticle catalyst for semihydrogenation of alkynes

Ru nanoparticles were used as catalysts for semihydrogenation of alkynes for the first time. Poly(ethylene glycol) (PEG)-stabilized Ru nanoparticles were used as catalysts for semihydrogenation of various terminal alkynes in thermoregulated PEG biphasic system, which allows for not only an efficient homogeneous catalytic reaction, but also an easy biphasic separation and reuse of catalyst. Under the optimized conditions, various terminal alkynes were hydrogenated to the corresponding alkenes with high selectivity. After reaction, the Ru nanoparticle catalyst could be separated from products by simple phase separation and recycled for ten times without evident loss in activity and selectivity.     

NH2SO3H-SiO2:一种经济高效可重复利用的糖类全乙酰催化剂

在糖化学中全乙酰保护的糖类化合物是非常便宜而且用途广泛的起始原料.对于糖类的全乙酰化反应,NH2SO3H-SiO2是一种高效的催化剂,以各种糖为底物收率均超过90%.回收的NH2SO3H-SiO2可以重复使用而活性没有明显下降.     

Acidic properties of caosio2 binary oxide catalyst and Activity for acid catalysis

A series of CaO-SiO₂ catalysts were prepared by coprecipitation from the mixed solution of calcium chloride and sodium silicate. The addition of CaO to SiO₂ caused the increase of acidity and the shift of O-H and Si-O stretching bands of the silanol group to a lower frequency in proportion to the CaO content. The acid structure of CaOSiO₂ agreed with that proposed by Tanabe et al.. Catalytic activity for 2-propanol dehydration and cumene dealkylation increased in relation to the increase of acidity and band shift to a lower frequency.     

Novel amino acid ionic liquids prepared via one-step lactam hydrolysis for the highly efficient capture of CO2

This article proposes for the first time the preparation of a series of amino acid ionic liquids (AAILs) via one-step hydrolysis of cheap lactams for the capture of CO₂. The structures of the prepared AAILs are confirmed using NMR, FTIR, and ESI-MS, and their physical properties are also determined. It is found that these AAILs are reversible CO₂ absorbents with very high absorption capacities (0.15 to 0.18 g·g⁻¹ at 313.2 K and 1.0 bar), better than almost all task-specific ionic liquids reported in literatures. The absorption mechanism is also elucidated to be a combination of 1:1 and 2:1 stoichiometric reaction of AAILs with CO₂ from NMR, FTIR, reaction equilibrium thermodynamical modeling and quantum calculations. The AAILs have the advantages of simple synthesis, high yield, and using available cheap raw materials. It is believed that this kind of AAILs have great potentials to be used as efficient CO₂ absorbents.     

PEG-anchored rhodium polyether diphosphinite complex as an efficient homogeneous and recyclable catalyst for hydroaminomethylation of olefins

A recyclable rhodium polyether diphosphinite complex anchored in polyethylene glycol [RhPEGD] was studied for hydroaminomethylation of various olefins with primary and secondary amines. The protocol was optimized with respect to various reaction parameters and the general applicability of catalyst for hydroaminomethylation of different functionalized olefins with corresponding amines was investigated. During the course of reaction, catalyst was soluble with reactants/products while could be quantitatively separated from reaction media in biphasic form by addition of anti-solvent on completion of reaction. The catalyst exhibited remarkable activity and was subsequently recycled up to five consecutive cycles.     

Benzylsulfonic acid functionalized mesoporous Zr-TMS catalysts: An efficient and recyclable catalyst for the preparation of coumarin derivatives by Pechmann condensation reaction

Benzylsulfonic acid functionalized mesoporous Zr-TMS (Zr-TMS-BSA, Zr-TMS, zirconia based transition metal oxide mesoporous molecular sieves) catalyst is used as an alternative to conventional acid catalysts in the von Pechmann condensation of aromatic alcohols with ethyl acetoacetate leading to the formation of coumarin derivatives in solvent free condition at 150 °C. Three types of coumarins, 7-hydroxy-4-methylcoumarin (β-methylumbelliferone), 7-methoxy-4-methylcoumarin (Methyl-4-methylumbelliferyl ether) and 7,8-benzo-4-methylcoumarin derivatives have been prepared using resorcinol, 3-methoxyphenol and 1-naphthol, respectively. The catalytic activity and the recycle studies of the catalyst in all the three reactions proved the superior performance of the catalyst. Further the products were confirmed by GC, elemental analysis, melting point and NMR techniques. Finally, the probable mechanism for Pechmann condensation using Zr-TMS-BSA catalyst has been reported.     

化学吸收剂强化微藻固碳研究进展

微藻固碳可缓解因化石燃料燃烧所造成的全球性气候变化和能源危机而受到广泛关注,但固碳效率低是限制其广泛应用的主要障碍,目前,化学吸收剂强化微藻固碳技术逐渐兴起。本文从培养液环境特征和微藻固碳生理生化表型特征两方面对化学吸收剂强化微藻固碳研究进行梳理和总结,其中所涉及的调变参数包括：化学 吸收剂种类、添加量、添加方式、添加时期等。最后,评述了现有化学吸收剂强化微藻固碳技术存在的共性问 题——作用机制和设计原则不清,并就该问题从微观-介观-宏观3个层面提出解决路径。运用组学分析技术,探究化学吸收剂强化微藻固碳的调控机制和本质原因;结合“光化学-原位微量热”测试技术掌握化学吸收剂强化微藻固碳的共性途径及其变化规律;通过可视化实验方法阐明CO₂供应、溶解、传递和固定之间的平衡关系。实现化学吸收剂的精准调控,提高微藻固碳效率。     

Heterogeneous amino acid-based tungstophosphoric acids as efficient and recyclable catalysts for selective oxidation of benzyl alcohol

A series of organic-inorganic composite catalysts, prepared by modifying tungstophosphoric acid (TPA; H₃PW₁₂O₄₀) with different amino acids such as phenylalanine (Phe), alanine (Ala), and glycine (Gly) were synthesized. The physicochemical and acidic properties of these (MH) _x H_3?x PW₁₂O₄₀ (M=Phe, Ala, and Gly; x=1–3) composite materials were characterized by a variety of different analytical and spectroscopic techniques, namely TGA, XRD, FT-IR, XPS, and NMR, and exploited as heterogeneous catalysts for selective oxidation of benzyl alcohol (BzOH) with hydrogen peroxide (H₂O₂). Among them, the [PheH]H₂PW₁₂O₄₀ catalyst exhibited the best oxidative activity with an excellent BzOH conversion of 99.0% and a desirable benzaldehyde (BzH) selectivity of 99.6%. Further kinetic studies and model analysis by response surface methodology (RSM) revealed that the oxidation of BzOH with H₂O₂ follows a second-order reaction with an activation energy of 56.7 kJ·mol^?1 under optimized experimental variables: BzOH/H₂O₂ molar ratio=1 : 1.5 mol/mol, amount of catalyst=6.1 wt%, reaction time (x₃)=3.8 h, and amount of water (x₄)=30.2 mL.     

琥珀酸发酵过程中固定CO_2的研究进展

随着全球温室效应问题日趋严峻,如何实现CO2的减排成为当今社会各界关注的焦点。本文以琥珀酸发酵过程中固定CO2为出发点,通过CO2固定产生琥珀酸的微生物及产琥珀酸的原理、CO2固定过程优化以及对CO2固定过程的基因改造等方面概述了琥珀酸发酵过程中固定CO2的研究进展。同时指出,基因工程改造将会成为以后研究的重心。考虑到实际应用过程中放大的重要性,在琥珀酸发酵过程中固定CO2的反应条件优化对于与其它发酵产CO2的过程的耦合也将显得日益重要,应加强这一方面的研究。     

ZrOCl2.8H2O/SiO2: An efficient and recyclable catalyst for the preparation of coumarin derivatives by Pechmann condensation reaction

Silica gel supported zirconyl chloride octahydrate was found to be an efficient and recyclable catalyst for the synthesis of a series of biologically important molecules in high turnover numbers and rates. Several substituted coumarins can be prepared in high yield and purity by direct reaction of β-keto esters and phenol derivatives in the presence of a catalytic amount of ZrOCl₂.8H₂O/SiO₂ as Lewis acid and at ambient temperature under solvent-free conditions. This method which is called Pechmann condensation is a very easy and a rapid reaction for the synthesis of coumarin derivatives.     

Periodic mesoporous silica chloride (PMSCl) as an efficient and recyclable catalyst for the Pechmann reaction

Periodic mesoporous silica chloride (PMSCl) with 2D P₆mm hexagonal structure which can be prepared by a simple procedure is reported to act as an efficient and recyclable catalyst for the conversion of a variety of phenols into their corresponding coumarins through Pechmann reaction. The reactions were conducted under solvent-free conditions in good to excellent yields.     

BiOCl/g-C3N4异质结催化剂可见光催化还原CO2

以KCl、Bi（NO₃）₃和类石墨氮化碳（g-C₃N₄）为前体,采用水热法成功制备了BiOCl/g-C₃N₄异质结光催化剂,并进行可见光催化还原CO₂,考察了催化剂的活性及稳定性,同时研究BiOCl：g-C₃N₄（摩尔比）、催化剂用量和光照强度对光催化还原CO₂的影响。结果表明,在水蒸气的存在下,BiOCl/g-C₃N₄较纯BiOCl和g-C₃N₄具有更高的光催化还原CO₂活性,在催化剂用量为0.1 g,光照强度为2.413×10^-6 einstein·min^-1·cm^-2,BiOCl：g-C₃N₄摩尔比为1：1的异质结催化剂显示了最高的光催化还原CO₂活性,且可见光催化剂在5次套用实验后其活性基本不变。基于X射线衍射（XRD）、扫描电子显微镜（SEM）、透射电子显微镜（TEM）、X射线光电子能谱（XPS）、比表面积测试（BET）和紫外-可见（UV-vis）吸收光谱表征,可以推断BiOCl和g-C₃N₄之间形成的p-n结能有效分离光生电子和空穴,是增强光催化剂活性的主要原因。     

Amberlyst A-21: An efficient, cost-effective and recyclable catalyst for the synthesis of substituted 4H-chromenes

A variety of substituted 4H-chromene derivatives have been synthesized in good to excellent yields from o-hydroxybenzaldehydes and ethyl cyanoacetate or malononitrile in ethanol using inexpensive and reusable catalyst i.e., Amberlyst A-21^® under mild reaction conditions. The recovered activated catalyst is recycled in five times subsequent runs with no decrease in activity. The use of reusable catalyst makes this procedure quite simple, more convenient, economically viable and environmentally friendly.     

二氧化碳与环氧烷开环共聚催化剂研究进展

综述了二氧化碳与环氧烷开环共聚制备聚碳酸酯的各类催化剂的研究进展,指出了研制高效、制备工艺简单、廉价易回收的环境友好催化剂仍是合成聚碳酸酯这一利用方式的研究重点,为二氧化碳的减排和资源化利用提供参考。     

分子筛在双功能催化剂中催化CO/CO2加氢研究进展

双功能催化剂可将CO/CO_2加氢直接合成低碳烯烃、芳烃和汽油等,具有工艺流程短、能耗低的优势。双功能催化剂由金属氧化物和分子筛两部分组成,分子筛特定的腔体结构、酸性质及与金属氧化物的结合方式等均可显著影响其催化性能。该文综述了近年来分子筛在双功能催化剂中用于CO/CO_2加氢反应的研究进展,简述了分子筛的类型、酸性质、形貌及颗粒尺寸、金属改性、分子筛与金属氧化物的结合方式等对双功能催化剂催化性能的影响规律,展望了双功能催化剂中分子筛的发展趋势。     

Sulfamic acid as an efficient and recyclable catalyst for the ring opening of epoxides with amines and anilines: An easy synthesis of β-amino alcohols under solvent-free conditions

Application of sulfamic acid as an efficient and green catalyst for the ring opening of epoxides by aliphatic and aromatic amines under solvent-free conditions is described. In this process the use of basic neutralization agent was not required due to the intrinsic zwitterionic property of sulfamic acid. The salient features of this methodology are cheaper process, easy availability of the catalyst, versatility, and the catalyst can be recovered after completion of the reaction and can be recycled without affecting the catalytic property.     

Trichloroisocyanuric acid,a new and efficient catalyst for the synthesis of dihydropyrimidinones

An efficient three-component synthesis of 3,4-dihydropyrimidinones using trichloroisocyanuric acid (TCCA) as a mild, homogeneous and neutral catalyst for Biginelli reaction in ethanol or DMF under reflux condition and microwave irradiation is described. Yields are excellent in either of the two conditions.     

I2 as a mild and efficient catalyst in deoxygenation of sulfoxides with thioacetic acid

An effective procedure for deoxygenation of sulfoxides to sulfides using thioacetic acid as a reducing agent and a catalytic amount of I₂ in MeCN at ambient temperature has been developed. Using this protocol, a variety of sulfoxides including benzyl, allyl, alkyl and aryl sulfoxides have been successfully reduced to the corresponding sulfides in excellent yields.