An efficient unsupported nanoporous nickel (NiNPore) material for the hydrogenation of carbonates to formic acid (FA) in water was investigated for the first time. NiNPore is an environmentally benign catalyst and it exhibited remarkable catalytic activity in the reduction of a wide range of carbonates to afford formic acid in excellent yields with high selectivity, and maximum values of 86.6% from NaHCO3 and even up to 92.1% from KHCO3 were obtained. The hydrogen pressure and pKa of the carbonates had a significant influence on the formation of FA. The catalyst was easily recovered and could be recycled at least five times without leaching and loss of activity. The present study demonstrated a potential application for the synthesis of FA from CO2 or carbonate compounds.

Novel reduced graphene oxide and carbon nanotube (rGO/CNT) hybrid fibers were prepared using a facial low-temperature chemical reduction self-assembly with vitamin C as the reducing agent. Mechanical measurements showed that hybrid fibers with an ultimate elongation of 150% had better mechanical properties than the single rGO fiber with an ultimate elongation of 105%. Cyclic voltammetry (CV) results showed that rGO/CNTs hybrid fibers exhibited better electrochemical performance than the rGO fiber because of the larger CV curve area of the former. The volumetric specific capacitance of the rGO/CNTs electrode was 559.9 F cm−3, and its qualitative specific capacitance was 59.76 F g−1 at a high current density of 1 A g−1. Both the volumetric specific capacitance and qualitative specific capacitance of the rGO/CNTs hybrid fibers were higher than those of single rGO fibers, particularly at low sweep speed. The scanning electron microscopy and transmission electron microscopy images of the rGO/CNTs composite fiber clearly showed the rGO and CNTs co-assembly and the interconnected porous structure formation. In the hybrid nanostructure, CNTs served as a reinforced bar, and the synergic effect between rGO and CNTs led to hybrid fibers with enhanced mechanical and electrochemical performances. The flexible rGO/CNT hybrid fibers showed large volumetric capacity, good rate capability, high stability and excellent flexibility. The micro-SCs made of the rGO/CNT hybrid fibers electrode are ideal energy-storage devices for next-generation flexible wearable electronics.

A new non-fermentative process for the transformation of biomass carbohydrates and lactic acid (LA) into propionic acid (PA) was first reported over a cobalt catalyst in water. The Co catalyst exhibited high catalytic activity for the formation of PA with Zn as a reductant. Various parameters, such as catalyst loading, Zn weight, water volume, temperature and reaction time, were investigated to improve the yield of PA, and the maximum value of 58.8% was achieved in the presence of 4 mmol Co and 10 mmol Zn in 7.5 mL H2O at 250 °C for 2 h. The recyclability of the Co catalyst showed that Co could be effectively repeated four times without the loss of activity. Moreover, the result showed that in situ-formed ZnO by oxidation of Zn in water could efficiently enhance the catalytic activity of the Co catalyst in the conversion of LA. Besides, direct conversion of carbohydrate biomass, such as glucose, cellulose and starch, or a similar compound such as glycolic acid also afforded the desired products. The present study provides great significance for practical application on the production of PA from LA and biomass carbohydrates.

•A structure-activity controllable synthesis of skeletal CuAlZn catalyst for hydrogenation of bicarbonate to formic acid in water was reported.•Skeletal CuAlZn exhibited high catalytic activity for hydrogenation of NaHCO3 to formic acid.•The leaching process could regulate the catalyst surface area and composition and thereby controlled activity of CuAlZn.In this paper, a structure-activity controllable synthesis of ternary skeletal CuAlZn catalyst for NaHCO3 hydrogenation to produce formic acid was first investigated. Several kinds of Cu alloy and/or the synthetic methods were considered and their catalytic activities for hydrogenation of NaHCO3 were discussed. The results found that skeletal CuAlZn-2.5 h catalyst exhibited great catalytic activity to afford the maximum value of 86.1% of formic acid with 6 MPa H2 at 200 °C for 4 h. Reusability showed skeletal CuAlZn-2.5 h could still keep high catalytic activity for at least three times repeat. The present study provides an efficient and eco-friendly method for formic acid synthesis through the hydrogenation of NaHCO3 or/and CO2.Download high-res image (216KB)Download full-size image

A novel approach for the production of 2,5-hexanedione (HDN) and 3-methyl-2-cyclopenten-1-one (3-MCO) from 5-hydroxymethylfurfural (HMF) by water splitting with Zn is reported for the first time. The use of high temperature water (HTW) conditions is the key for the efficient conversion of HMF to HDN and 3-MCO. Parameters regarding the Zn amount, temperature and reaction time are optimized and HDN and 3-MCO are produced in 27.3% and 30.5% yields, respectively. The roles of HTW and ZnO obtained by oxidation of Zn in water for the conversion of HMF, together with intermediate structures, are discussed to understand the mechanism of the reaction.

•Direct and efficient conversion of ethylene carbonate to ethylene glycol in aqueous media was developed.•The transformation of ethylene carbonate provided high selectivity and high yield.•No any catalysts and additives were added in the process.A novel process for the conversion of ethylene carbonate (EC) to ethylene glycol (EG) in high temperature water was investigated. As a result, even there is no external catalyst and additive, the reaction of EC proceeded well and provided the desired EG in 99% yield with 25% water filling at 250 °C for 2 h. Moreover, only CO2 as by-product was observed in the process. High temperature water exhibits an unique merits and plays an catalytic role for EC conversion. From viewpoint of practice, this work provides a simple, environmentally benign, catalyst/additive-free process for the production of ethylene glycol from ethylene carbonate.

An efficient process for the production of levulinate esters from biomass-derived furfuryl alcohol in liquid alcohol over commercial α-Fe2O3 was firstly investigated. Among the catalysts we tested, α-Fe2O3, a cheap, commercially available and environmentally benign catalyst, exhibited a remarkable catalytic performance for the transformation and gives levulinate esters in good yield compared to the previous studies. The corresponding esters such as methyl levulinate, ethyl levulinate and butyl levulinate were obtained in high yields under optimized reaction conditions. Several influence factors for the formation of levulinate esters were also discussed. A plausible reaction mechanism for the formation of levulinate ester from furfuryl alcohol was proposed. From the viewpoint of practice and economy, the present study provides a potential application for the efficient synthesis of fine chemicals from biomass-derived compounds over cheap, commercially available and environmentally benign catalysts.

A novel and efficient strategy for one-step synthesis of allylated quinolines and isoquinolines via palladium-catalyzed cyclization–allylation of azides and allyl methyl carbonate is developed for the first time. The results indicated that the regioselective synthesis of allyl- and diallyl-substituted quinolines/isoquinolines depends on different substituted groups at R1 and R4 positions, such as H or other groups. The reactions proceed smoothly in the presence of Pd(PPh3)4 and K3PO4 or NaOAc in DMF at 100 °C to give the corresponding allyl- and diallyl-substituted quinolines and isoquinolines in good to high yields.

The efficient conversion of biomass-derived glycolide into ethylene glycol over CuO in water was investigated. The reaction of glycolide was carried out with 25 mmol Zn and 6 mmol CuO with 25% water filling at 250 °C for 150 min, which yielded the desired ethylene glycol in 94% yield.

The palladium-catalyzed cyclization–allylation reaction of ortho-azido propynylbenzenes 1 and allyl methyl carbonate 2d gives the corresponding allylated quinolines in moderate to good yields. The reaction of 1-azido-2-(2-propynyl)benzene 1a proceeds smoothly with 10 mol % Pd(PPh3)4 and 5 equiv K3PO4 or NaOAc in DMF at 100 °C to afford 3,4-diallylquinoline 3a in 69% yield in the case of R2 = H and 3-allylquinoline 4 in 67% yield in the case of R2 ≠ H.

An efficient conversion of biomass-derived ethyl lactate to 1,2-propanediol (1,2-PDO) over CuO was investigated. Among the catalysts we tested, CuO, Cu2O and Co showed excellent catalytic activity for the conversion of ethyl lactate to 1,2-PDO in water, and CuO was more active and gave the best result. The 1,2-PDO yield of 93.6% was achieved when Zn acted as a reductant. The results indicated that in situ formed hydrogen by the oxidation of Zn in water is more effective than gaseous hydrogen, which failed to produce the 1,2-PDO from ethyl lactate. From a practical point of view, the present method may provide a useful route for the production of 1,2-PDO from ethyl lactate.An efficient conversion of biomass-derived ethyl lactate to 1,2-PDO over CuO was investigated. The results showed that CuO exhibited high catalytic activity for the conversion of ethyl lactate, and the 1,2-PDO yield of 93.6% was achieved when Zn acted as a reductant.Download full-size image

The efficient conversion of biomass-derived glycolide into ethylene glycol over CuO in water was investigated. The reaction of glycolide was carried out with 25 mmol Zn and 6 mmol CuO with 25% water filling at 250 °C for 150 min, which yielded the desired ethylene glycol in 94% yield.

A novel and efficient strategy for one-step synthesis of allylated quinolines and isoquinolines via palladium-catalyzed cyclization–allylation of azides and allyl methyl carbonate is developed for the first time. The results indicated that the regioselective synthesis of allyl- and diallyl-substituted quinolines/isoquinolines depends on different substituted groups at R1 and R4 positions, such as H or other groups. The reactions proceed smoothly in the presence of Pd(PPh3)4 and K3PO4 or NaOAc in DMF at 100 °C to give the corresponding allyl- and diallyl-substituted quinolines and isoquinolines in good to high yields.