离子液体催化甘油和尿素合成甘油碳酸酯

将一系列酸性、碱性和中性的功能化离子液体用于催化甘油和尿素合成甘油碳酸酯。结果表明,中性离子液体表现出更高的催化活性。离子液体阳离子和阴离子的协同效应促进了反应的进行,离子液体阳离子的正电性活化尿素,阴离子的负电性活化甘油,并且催化剂酸碱位点的平衡对催化反应过程也有一定的影响。此外,离子液体可以实现回收利用至少五次,且催化活性基本不变。采用功能化离子液体替代传统金属催化剂,减少了不可再生资源的利用,且所用原料为廉价易得的生物基原料,过程中也不使用有机溶剂,环境友好。     

Task-specific ionic liquids for carbon dioxide absorption and conversion into value-added products

Ionic liquids (ILs), by virtue of their special properties such as functional designability and high thermal stability, have been widely used as absorbent to CO₂ and catalyst for CO₂ conversion. This review summarizes the recent developments from 2019 to 2021 on task-specific ionic liquids (TSILs) with modulable properties by introducing specific functional groups to anions or/and cations for CO₂ absorption and conversion. The increase of basicity in TSILs by introducing amino/or amine groups or collaboration with multiple active sites of carboxyl, imidazolyl, pyridyl, and hydroxyl groups achieve high CO₂ affinity and absorption capacity. To solve the defects of high viscosity, ether groups are introduced to TSILs for CO₂ absorption. Besides, recent studies on CO₂ thermal catalytic conversion focused on the construction of C–O bonds and C–N bonds are also summarized. The catalytic activity of TSILs is enhanced by improving the synergy effect of different functional groups on anions and cations. It is expected that this minireview will provide the understanding of the current developments and perspective for practical CO₂ absorption and transformation by TSILs.     

High-entropy transition metal chalcogenides as electrocatalysts for renewable energy conversion

High-entropy transition metal chalcogenides (HE-TMCs) are advantageous in electrocatalytic applications compared to other entropy-stabilized systems owing to the greater orbital extension and energetic match of p-orbitals in chalcogenides with d-orbitals of the transition metals providing additional space to tailor their electronic structure. The high-configurational entropy of HE-TMCs leads to stabilization of cubic rock salt, wurtzite-type and hexagonally packed 2D structures. Due to the multi-element nature of HE-TMCs, the synergy among different elements results in tunable d- and p-band positions. As a consequence, the adsorption energies of electrocatalytic reaction intermediates can be tailored to enhance catalytic performance in water splitting and CO₂ reduction. Furthermore, the entropy-stabilized disordered microstructural state of the material endows HE-TMCs with improved corrosion resistance. Despite recent advances in HE-TMC electrocatalysis, challenges such as identification and synthesis of efficient HE-TMCs as well as the identification of catalytically active sites and reaction mechanisms on HE-TMCs remain to be investigated.     

甘油碳酸酯合成方法概述

甘油碳酸酯（glycerol carbonate、4-hydroxymethyl-1,3-dioxolan-2-one）,又称为碳酸甘油酯、4-羟甲基-2-羰基-1,3-二氧戊环,主要用作反应中间体和溶剂,或与异氰酸盐、丙烯酸酯类产品反应生产聚合物用于涂料、胶黏剂和润滑剂等领域.尤其值得指出的是,甘油碳酸酯还是一种新型的多功能合成分子,由于分子内同时含有羟基和羰基官能团,     

P-doped g-C3N4 as an efficient photocatalyst for CO2 conversion into value-added materials: a joint experimental and theoretical study

The photocatalytic yield of g-C₃N₄ for CO₂ reduction was modified by phosphorus doping. Possible reaction pathways for CO₂ reduction on the P-doped g-C₃N₄ (PCN) surface were investigated by density function theory calculations for the first time. The experimental results showed that P doping increases the carriers' lifetime, which improves the production of CH₄ through the increase in the driving force of the electrons. The partial density of states of the PCN showed that the valence band maximum and conduction band minimum are composed of p_x, p_y, and, s orbitals of the N atoms and p_z states of carbon, nitrogen, and phosphorus, respectively. Mechanism studies confirm that formic acid, formaldehyde, methanol, and methane are the most probable products. Methane, having positive adsorption energy, can be easily desorbed from the PCN surface, and the Gibbs activation energy of the final step is 1.98 eV. The formation of H₂COOH is the rate-determining step.     

Chemoselective catalytic conversion of glycerol as a biorenewable source to valuable commodity chemicals

New opportunities for the conversion of glycerol into value-added chemicals have emerged in recent years as a result of glycerol's unique structure, properties, bioavailability, and renewability. Glycerol is currently produced in large amounts during the transesterification of fatty acids into biodiesel and as such represents a useful by-product. This paper provides a comprehensive review and critical analysis on the different reaction pathways for catalytic conversion of glycerol into commodity chemicals, including selective oxidation, selective hydrogenolysis, selective dehydration, pyrolysis and gasification, steam reforming, thermal reduction into syngas, selective transesterification, selective etherification, oligomerization and polymerization, and conversion of glycerol into glycerol carbonate.     

An efficient catalytic system for the synthesis of glycerol carbonate by oxidative carbonylation of glycerol

Glycerol carbonate was synthesized by the oxidative carbonylation of glycerol catalyzed by the commercial Pd/C with the aid of NaI.High conversion of glycerol(82.2%),selectivity to glycerol carbonate(>99%),and TOF(900 h–1)were obtained under the conditions of 5 MPa(pCO:pO2=2:1),140 oC,2 h.The highly active palladium species were generated in situ by dissolution from the carbon support and stabilized by re-deposition onto the support surface after the reaction was finished.Palladium dissolution and re-deposition were crucial and inherent parts of the catalytic cycle,which involved heterogeneous reactions.This Pd/C catalyst could be recycled and efficiently reused for four times with a gradual decrease in activity.Moreover,the influences of various parameters,e.g.,types of catalysts,solvents,additives,reaction temperature,pressure,and time on the conversion of glycerol were investigated.A reaction mechanism was proposed for oxidative carbonylation of glycerol to glycerol carbonate.     

Tin (II) chloride in glycerol as a titrimetric reagent in carbonate media

Tin(II) chloride solutions in glycerol are much more stable to light and atmospheric oxidation than the usual hydrochloric acid solutions, although the general reducing properties of the solutions are similar. In bicarbonate media, ferricyanide and chromate can be readily determined; some possible applications are outlined.     

Application of N-thiocyanatosuccinimide as a reagent for the facile conversion of epoxides into thiocyanohydrines

The use of in situ generated N-thiocyanatosuccinimide with NH₄SCN offers an efficient reagent system for the conversion of epoxides into their corresponding thiocyanohydrines in good to high yields.The major advantages of this method are as follows:use of cheap reagent,high regioselectivity,simple availability of reagent,ease of workup of the reaction.     

Novel hybrid process for the conversion of microcrystalline cellulose to value-added chemicals: part 2: effect of constant voltage on product selectivity

In this study, electrochemical degradation of microcrystalline cellulose (MCC) under hot-compressed water was investigated via application of constant voltage on reaction medium. Constant voltage ranges from 2.5 to 8.0 V was applied between anode (Titanium) and cathode (reactor wall). As an electrolyte and proton source 5–25 mM of H₂SO₄ was used. Reactions were carried out in a specially designed batch reactor (450 mL) made of T316 for 240 min at temperature of 200 °C.MCC decomposition products such as glucose, fructose, furfural, 5-HMF and levulinic acid were detected and quantified by High Performance Liquid Chromatography (HPLC). In the absence of electrolyte, applied voltage (2.5 and 4.0 V) decreased the total organic carbon (TOC) yield, in contrast at 8.0 V, TOC yield increased to 13%. Application of 8.0 V in hydrothermal conditions alter MCC decomposition pathway selectively to furfural (15%). Addition of electrolyte (5 mM, H₂SO₄) and application of 2.5 V potential increased TOC (54%) and changed the decomposition pathway in favor of 5-HMF (30%) and levulinic acid (21%). The structural changes in solid residues of electrochemically reacted MCC was analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and found that MCC particles functionalized by carboxylic acid and sulfonated groups by the application of constant voltage to reaction medium. In the presence of electrolyte, under certain voltage (2.5 V), functionalization of solid particles became more obvious in FTIR spectrum results. Therefore, change in the selectivity values of degradation products were conducted with the functionalization of MCC particles due to applied voltage under sub-critical conditions.     

Catalytic performance of polymer-supported ionic liquids in the synthesis of glycerol carbonate from glycerol and urea

Research on Chemical Intermediates - Ionic liquids (ILs) immobilized onto a structurally modified Merrifield peptide resin (MPR) were prepared through the reaction of imidazole with alkoxylated...     

Aqueous DMF-potassium carbonate as a substitute for thallium and silver additives in the palladium-catalyzed conversion of aryl bromides to acetyl arenes

Highly selective palladium-catalyzed internal alpha-arylations of alkyl vinyl ethers with aryl and heteroaryl bromides were conveniently conducted in aqueous DMF with potassium carbonate as base and with DPPP as bidentate ligand. The corresponding acetyl arene products were, after hydrolysis, isolated in good to excellent yields. This Heck reaction procedure does not require toxic thallium or expensive silver salt additives, is promoted by water, and is suggested to proceed via charged organopalladium intermediates. Single-mode microwave irradiation was utilized in one example to shorten the reaction time.     

Rare earth‐doped calcium‐based magnetic catalysts for transesterification of glycerol to glycerol carbonate

Several rare earth‐doped, calcium‐based magnetic catalysts were prepared for the synthesis of glycerol carbonate. The basicity and basic strength analysis of the catalysts showed that the doping of rare earth improved the basicity of the catalysts, and the doping of lanthanum maximized it. In addition, with the doping of lanthanum, the particle size of the catalyst became smaller to promote the organic reactants near the active sites of catalysts, thereby effectively improving the performance. NiFe₂O₄@[CaO‐La₂O₃] shows better catalytic performance with 99.0% yield of glycerol carbonate compared to the other catalysts. The NiFe₂O₄@(CaO‐La₂O₃) could be reused in six cycles without significant loss in activity.     

pH determination on a carbonate buffer by Harned cells of different designs

The carbonate solution is one of seven primary standard buffers set recently by the International Union of Pure and Applied Chemistry (IUPAC) recommendations (Buck et al., Pure Appl Chem 74:2169–2200, 2002). The peculiarity of the pH measurement of this buffer in a traditional Harned cell (classic cell) is due to the loss of carbon dioxide with hydrogen flow and the ensuing change of its chemical composition. This results in a continuous increase of the recorded electromotive force (E) of the cell. Therefore, almost all National Metrology Institutes (NMIs) are now using the extrapolation of measured E data to zero time point in order to find the initial pH. The National Metrology Institute of Japan (NMIJ) has developed a different design of Harned cell (NMIJ cell) with compensation of the lost carbon dioxide from the intermediary saturation vessel. The results of the study of the NMIJ cell are presented, together with those of the trilateral NMIJ–PTB–ZMK (NMI of Japan with the NMI of Germany [Physikalisch-Technische Bundesanstalt, PTB] and the German Centre for Measurements and Calibrations [Zentrum für Messen und Kalibrieren GmbH, ZMK]) comparison of pH values for the carbonate solution in different designs of Harned cell.

Valorisation of glycerol as renewable feedstock: comparison of the exploration of chemical transformation methods aided by high throughput experimentation

Renewable feedstocks have been in the spotlight of intensive research activities over the past 10 years. Glycerol is one of the feedstock molecules which has been the target of numerous research efforts, for a number of reasons. First of all glycerol is currently readily available due to the fact that it is a couple product of the first generation biodiesel production. Secondly glycerol can be taken as a representative model substrate to explore the options of selective conversion of sugar alcohols to products of value. In our paper we discuss potential routes for the valorisation of glycerol which lead to intermediates already established within the petrochemical value chain and illustrate what impact high throughput experimentation may have as a success factor on research and development for this field. As illustrative examples we have chosen the oxidative transformation of glycerol to acrolein and acrylic acid and the carbonylation of glycerol to C4-acids.