Baowen Zhou

A new porous Zr-containing catalyst with a phenate group: an efficient catalyst for the catalytic transfer hydrogenation of ethyl levulinate to γ-valerolactone

Catalytic transfer hydrogenation (CTH) of ethyl levulinate (EL) to gamma-valerolactone (GVL) is a very attractive reaction in the field of biomass transformation. In this work, a new porous Zr-containing catalyst with a phenate group in its structure was prepared by the coprecipitation of 4-hydroxybenzoic acid dipotassium salt and ZrOCl2 (Zr-HBA) in water and characterized by powder X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), N-2 adsorption-desorption, and Fourier transform infrared spectroscopy. The Zr-HBA was used as the catalyst for CTH of EL to GVL in the presence of isopropanol, and the effects of temperature, time, and the amount of the catalyst on the reaction were studied. It was found that Zr-HBA was very active for the reaction and a GVL yield of 94.4% could be achieved. Meanwhile, the Zr-HBA could be reused at least five times without a notable decrease in activity and selectivity. The main reason for the high catalytic activity of the Zr-HBA was that the existence of a phenate in the structure of Zr-HBA increased the basicity of the catalyst, which is favourable for the CTH of EL.

Porous Zirconium–Phytic Acid Hybrid: a Highly Efficient Catalyst for Meerwein–Ponndorf–Verley Reductions

The utilization of compounds from natural sources to prepare functional materials is of great importance. Herein, we describe for the first time the preparation of organic-inorganic hybrid catalysts by using natural phytic acid as building block. Zirconium phosphonate (Zr-PhyA) was synthesized by reaction of phytic acid and ZrCl4 and was obtained as a mesoporous material with pore sizes centered around 8.5 nm. Zr-PhyA was used to catalyze the mild and selective Meerwein-Ponndorf-Verley (MPV) reduction of various carbonyl compounds, e.g., of levulinic acid and its esters into γ-valerolactone. Further studies indicated that both Zr and phosphate groups contribute significantly to the excellent performance of Zr-PhyA.

Biomass-derived γ-valerolactone as an efficient solvent and catalyst for the transformation of CO2 to formamides

Efficient conversion of carbon dioxide (CO2) into valuable chemicals is a very attractive topic. Herein, we conducted the first work on the utilization of biomass-derived γ-valerolactone (GVL) as the solvent and catalyst for transformation of CO2 with various primary and secondary amines in the presence of phenylsilane (PhSiH3), and the corresponding desired formamides were produced with high yields without any additional catalyst. Systematic studies indicated that the lactone structure of GVL played a key role in the formation of the active silyl formates and the activation of N–H bonds in amines, thus leading to the excellent performance of GVL for the catalytic reactions.

Very efficient conversion of glucose to 5-hydroxymethylfurfural in DBU-based ionic liquids with benzenesulfonate anion.

Efficient conversion of glucose to 5-hydroxymethylfurfural (HMF), an important platform molecular for fuels and chemicals, is a promising topic in green chemistry. In this work, several new DBU-based (DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene) ionic liquids (ILs) with benzene sulfonate (BS) anion were synthesized and used as the solvents for the dehydration of glucose to HMF. It was found that all the ILs were excellent solvents for the dehydration of glucose to form HMF using CrCl3 as the catalyst. The effects of various factors, such as kind of catalysts, catalyst amount, reaction time and reaction temperature, on the yields of HMF were studied systematically in the Et-DBUBS/CrCl3 catalytic system. The yield of HMF from glucose could reach 83.4% under the optimized reaction conditions, and the reasons for the high yield were investigated on the basis of control experiments. The Et-DBUBS/CrCl3 system could be reused at least five times without considerable reduction in the efficiency. Further study indicated that the catalytic system was also very efficient for transformation of fructose, inulin, and cellobiose to HMF.

Light-driven integration of the reduction of nitrobenzene to aniline and the transformation of glycerol into valuable chemicals in water

Both effective utilization of glycerol and reduction of nitrobenzene to aniline are of great importance. It is very interesting to integrate these processes. This work reports the integration of the efficient conversion of nitrobenzene to aniline and transformation of glycerol to valuable chemicals driven by UV-light using Pd/TiO2 as the catalyst and water as the solvent at ambient temperature. In this integrated reaction process, glycerol acted as the hydrogen source for the reduction of nitrobenzene to aniline and the glycerol was converted into value-added chemicals simultaneously. At the optimized conditions, nitrobenzene could be converted completely with aniline selectivity of 95% with a nitrobenzene to glycerol mole ratio of 1:5. At the same time, glycerol was oxidized to form fine chemicals, including 1,3-dihydroxyacetone, glyceraldehyde, formic acid, and hydroxyacetic acid. This work opens up a new and effective way for transformation of glycerol to fine chemicals and production of aniline from nitrobenzene.

Cooperative catalysis of Pt/C and acid resin for the production of 2,5-dimethyltetrahydrofuran from biomass derived 2,5-hexanedione under mild conditions

Conversion of biomass into 2,5-dimethyltetrahydrofuran (DMTHF), an excellent fuel additive, solvent, and industrial intermediate, is an important reaction in green chemistry. In this work, different combinations of supported metal catalysts and solid acids were investigated for the synthesis of DMTHF from biomass derived diketone (2,5-hexanedione, 2,5-HD). The results showed that commercial Pt/C and solid acid Amberlite®IR-120H had an excellent cooperative effect on the reaction. 2,5-HD could be converted into DMTHF with a yield up to 99% under milder conditions. Further experiments indicated that 2,5-hexanediol (2,5-HDO) is a key intermediate in the reaction. The catalyst system could be facilely recovered due to the heterogeneity and reused several times without notable change in the performance.

Preparation of Ru/Graphene using Glucose as Carbon Source and Hydrogenation of Levulinic Acid to γ-Valerolactone.

The preparation of functional materials and value-added chemicals using biomass-derived feedstocks is an interesting topic. Herein, we propose a method to prepare Ru/graphene catalyst using glucose as the carbon source. The catalyst was characterized by scanning and transmission electron microscopies, Raman and X-ray photoelectron spectroscopies, and X-ray diffraction. It was found that Ru particles of 2-6 nm were supported uniformly on high-quality graphene. The performance of the Ru/graphene for hydrogenation of levulinic acid to γ-valerolactone was studied. The Ru/graphene had much higher activity for the hydrogenation reaction than commercial Ru/C, and was active even at room temperature. The high activity was partially due to the unique structure of graphene, which resulted in an electron-enriched Ru nanocatalyst. In addition, the Ru/graphene could be reused at least four times without considerable decrease in activity, indicating the excellent stability of the catalyst under our conditions.

Simultaneous and selective transformation of glucose to arabinose and nitrosobenzene to azoxybenzene driven by visible-light

Both the selective conversion of glucose into arabinose and the reduction of nitrosobenzene to azoxybenzene are very important but challenging processes. Herein we carried out the first work on the simultaneous transformation of glucose to arabinose and of nitrosobenzene to azoxybenzene by photocatalysis. It was found that Pd nanoparticles supported on mesoporous CdS were very active and selective for the reactions in water under visible light irradiation. Nitrosobenzene could be reduced to azoxybenzene with a selectivity of 92% by hydrogen from water and glucose. More importantly, glucose was oxidized to arabinose with high selectivity (70%) by photoexcited holes. The reaction mechanism and the reason for the high selectivity were studied using control experiments.

Highly selective photocatalytic oxidation of biomass-derived chemicals to carboxyl compounds over Au/TiO2

Highly selective transformation of biomass-derived chemicals into value-added chemicals is of great importance. In this work, selective photooxidation of various biomass-derived chemicals, including ethanol, glucose, xylose, 2-furaldehyde, 5-hydroxymethyl-2-furfural, and furfuralcohol to the corresponding carboxyl compounds was studied using atmospheric air as the oxidant at ambient temperature. It was found that the reactions could be carried out efficiently over Au nanoparticles (AuNPs) supported on TiO2 (AuNPs/TiO2) under both ultraviolet (UV) and visible light in Na2CO3 aqueous solution. Under the optimized conditions, the selectivities for desired products were higher than 95% for all the reactions. Detailed studies indicated that the surface plasmon resonance of AuNPs and the band-gap photoexcitation of TiO2 were responsible for visible-light-responding and UV-light-responding activities, respectively. Na2CO3 acted as the promoter for the visible-light-induced oxidation and the inhibitor of reactive oxygen species with strong oxidation power under UV light.