Qinggong Zhu

Transformation of Atmospheric CO2 Catalyzed by Protic Ionic Liquids: Efficient Synthesis of 2‐Oxazolidinones

Protic ionic liquids (PILs), such as 1,8-diazabicyclo[5.4.0]-7-undecenium 2-methylimidazolide [DBUH][MIm], can catalyze the reaction of atmospheric CO2 with a broad range of propargylic amines to form the corresponding 2-oxazolidinones. The products are formed in high yields under mild, metal-free conditions. The cheaper and greener PILs can be easily recycled and reused at least five times without a decrease in the catalytic activity and selectivity. A reaction mechanism was proposed on the basis of a detailed DFT study which indicates that both the cation and anion of the PIL play key synergistic roles in accelerating the reaction.

Cobalt catalysts: very efficient for hydrogenation of biomass-derived ethyl levulinate to gamma-valerolactone under mild conditions

Hydrogenation of ester levulinate to gamma-valerolactone (GVL) is an interesting reaction in biomass conversion to produce value-added chemicals. Exploration of efficient and robust catalysts is crucial for large-scale application. In this work, we conducted the reaction catalyzed by a Co catalyst, and it was found that commercially available Co3O4 was very efficient for this reaction under mild conditions after reduction by H2. The effects of temperature, hydrogen pressure, amount of the catalyst used, and reaction time on the yield of GVL were studied. Under optimized conditions, the yield of GVL could reach 98%. The catalyst could be reused at least 10 times without notable loss of the activity and selectivity. The catalyst was characterized by scanning electron spectroscopy (SEM), transmission electron spectroscopy (TEM), X-ray photoelectron spectroscopy (XPS), and powder X-ray diffraction (XRD). It was demonstrated that the metallic Co0 was the active species for the hydrogenation reaction. As far as we know, this is the first work conducting the reaction using Co as the catalyst.

Zinc(II)-catalyzed reactions of carbon dioxide and propargylic alcohols to carbonates at room temperature

Carbon dioxide (CO2) is an abundant and renewable feedstock for the production of value-added chemicals. Herein, we carried out the first work to use ZnI2/NEt3 as the catalyst for the reactions of CO2 and propargylic alcohols to form α-alkylidene cyclic carbonates. It was discovered that the catalyst system could efficiently promote the reaction at room temperature under solvent-free conditions, and the yields of the target products could reach 99%. The zinc(II) and NEt3 play excellent synergistic roles in activating both CO2 and propargylic alcohols.

Molybdenum–Bismuth Bimetallic Chalcogenide Nanosheets for Highly Efficient Electrocatalytic Reduction of Carbon Dioxide to Methanol

Methanol is a very useful platform molecule and liquid fuel. Electrocatalytic reduction of CO2 to methanol is a promising route, which currently suffers from low efficiency and poor selectivity. Herein we report the first work to use a Mo-Bi bimetallic chalcogenide (BMC) as an electrocatalyst for CO2 reduction. By using the Mo-Bi BMC on carbon paper as the electrode and 1-butyl-3-methylimidazolium tetrafluoroborate in MeCN as the electrolyte, the Faradaic efficiency of methanol could reach 71.2 % with a current density of 12.1 mA cm(-2) , which is much higher than the best result reported to date. The superior performance of the electrode resulted from the excellent synergistic effect of Mo and Bi for producing methanol. The reaction mechanism was proposed and the reason for the synergistic effect of Mo and Bi was discussed on the basis of some control experiments. This work opens a way to produce methanol efficiently by electrochemical reduction of CO2 .

Efficient Reduction of CO2 into Formic Acid on a Lead or Tin Electrode using an Ionic Liquid Catholyte Mixture

Highly efficient electrochemical reduction of CO2 into value-added chemicals using cheap and easily prepared electrodes is environmentally and economically compelling. The first work on the electrocatalytic reduction of CO2 in ternary electrolytes containing ionic liquid, organic solvent, and H2 O is described. Addition of a small amount of H2 O to an ionic liquid/acetonitrile electrolyte mixture significantly enhanced the efficiency of the electrochemical reduction of CO2 into formic acid (HCOOH) on a Pb or Sn electrode, and the efficiency was extremely high using an ionic liquid/acetonitrile/H2 O ternary mixture. The partial current density for HCOOH reached 37.6 mA cm(-2) at a Faradaic efficiency of 91.6 %, which is much higher than all values reported to date for this reaction, including those using homogeneous and noble metal electrocatalysts. The reasons for such high efficiency were investigated using controlled experiments.

A route to convert CO2: synthesis of 3,4,5-trisubstituted oxazolones

Production of value-added chemicals using carbon dioxide (CO2) as a feedstock is favorable to the sustainable development of the chemical industry. In this work, we have discovered for the first time that CO2 can react with propargylic amines to produce 3,4,5-trisubstituted oxazolones, a class of very useful chemicals. It was found that the ionic liquid (IL) 1-butyl-3-methylimidazolium acetate ([Bmim][OAc]) can catalyze the reactions efficiently at atmospheric pressure under metal-free conditions. It was also found that [Bmim][OAc] and IL 1-butyl-3-methylimidazolium bis((trifluoromethyl)sulfonyl)imide ([Bmim][Tf2N]) have an excellent synergistic effect for promoting the reactions. The [Bmim][OAc]/[Bmim][Tf2N] catalytic system can be reused at least five times without loss in catalytic activity and selectivity. The reaction mechanism was proposed on the basis of density functional theory (DFT) calculation and the experimental results.

Highly efficient hydrogenation of carbon dioxide to methyl formate over supported gold catalysts

Transformation of carbon dioxide (CO2) into valuable chemicals is an interesting topic in green chemistry. Hydrogenation of CO2 to methyl formate (MF) in the presence of methanol is an important reaction. In this work, Au nanocatalysts immobilized on different supports were prepared and characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM) and X-ray photoelectron spectrometry (XPS). The catalytic performances of the catalysts for the reaction were studied. It was demonstrated that the Au/ZrO2, Au/CeO2 and Au/TiO2 were very active and selective for the reaction in the absence of any basic additives. The Au/ZrO2 was more active than Au/CeO2 and Au/TiO2 if the sizes of Au particles on the supports were similar. Moreover, for the Au/ZrO2 catalysts, Au particles with smaller size had higher activity. The possible mechanism of the catalytic reaction was proposed.

A strategy to overcome the thermodynamic limitation in CO2 conversion using ionic liquids and urea

Enhancing the equilibrium conversion of thermodynamically unfavorable reactions is a very interesting and challenging topic for chemists. The unique properties of ionic liquids (ILs) provide new opportunities to solve this problem. Herein a strategy is proposed to circumvent the thermodynamic limitation of chemical reactions using the designable and non-volatile nature of ILs. In this approach a reactant first reacts with a functional IL to form a high energy IL intermediate, which can further react with other reactants to yield products and regenerate the IL. To verify the feasibility of this strategy, the syntheses of dimethyl carbonate (DMC) and methyl formate (MF) via urea, which are very important reactions used to convert CO2 but are thermodynamically unfavorable, were conducted with the aid of a diol IL. It was found that the equilibrium yields of DMC and MF obtained by this methodology could be 64 times and 9 times higher, respectively, than those of the conventional methods.

Electrochemical reduction of CO 2 to CO using graphene oxide/carbon nanotube electrode in ionic liquid/acetonitrile system

Electrochemical reduction of CO2 to CO is an interesting topic. In this work, we prepared metal-free electrodes by depositing graphene oxide (GO), multi-walled carbon nanotube (MWCNT), and GO/MWCNT composites on carbon paper (CP) using electrophoretic deposition (EPD) method. The electrodes were characterized by different methods, such as X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical reduction of CO2 to CO was conducted on the electrodes in 1-butyl-3-methylimidazolium tetrafluoroborate ([Bmim]BF4)/acetonitrile (MeCN) electrolyte, and the composition of the electrolyte influenced the reaction significantly. It was demonstrated that GO/MWCNT-CP electrode was very effective for the reaction in IL (90 wt%)/MeCN binary mixture, the Faradaic efficiency of CO and current density were even higher than those on Au and Ag electrodes in the same electrolyte.

MoP Nanoparticles Supported on Indium‐Doped Porous Carbon: Outstanding Catalysts for Highly Efficient CO2 Electroreduction

Electrochemical reduction of CO2 into value-added product is an interesting area. MoP nanoparticles supported on porous carbon were synthesized using metal-organic frameworks as the carbon precursor, and initial work on CO2 electroreduction using the MoP-based catalyst were carried out. It was discovered that MoP nanoparticles supported on In-doped porous carbon had outstanding performance for CO2 reduction to formic acid. The Faradaic efficiency and current density could reach 96.5 % and 43.8 mA cm-2 , respectively, when using ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate as the supporting electrolyte. The current density is higher than those reported up to date with very high Faradaic efficiency. The MoP nanoparticles and the doped In2 O3 cooperated very well in catalyzing the CO2 electroreduction.