Xiuquan Jia

Direct conversion of fructose-based carbohydrates to 5-ethoxymethylfurfural catalyzed by AlCl3·6H2O/BF3·(Et)2O in ethanol

Direct conversion of fructose-based carbohydrates to 5-ethoxymethylfurfural (EMF) catalyzed by Lewis acid in ethanol was investigated. It was found that BF3·(Et)2O was favorable for 5-hydroxymethylfurfural (HMF) etherification to EMF. BF3·(Et)2O combination with AlCl3·6H2O with the molar ratio of 1 was an effective catalyst system for synthesis of EMF from fructose-based carbohydrates. 55.0%, 45.4% and 23.9% of EMF yields were obtained from fructose, inulin and sucrose under optimized conditions, respectively.

Aqueous phase hydrogenation of furfural to tetrahydrofurfuryl alcohol on alkaline earth metal modified Ni/Al2O3

Al2O3 modified by alkaline earth metals M–Al2O3 (M = Mg, Ca, Sr, Ba) was synthesised by coprecipitation method. The nickel-based catalysts supported by M–Al2O3 were prepared by impregnation method. The catalysts were characterized by TEM, N2 adsorption/desorption, XRD, H2-TPR, NH3-TPD and XPS, and used for the direct hydrogenation of furfural to tetrahydrofurfuryl alcohol (THFA) in water. The reaction was demonstrated to proceed through furfuryl alcohol as an intermediate. The modification of Al2O3 by alkaline earth metals has a significant effect on the activity and selectivity of THFA. A high yield of THFA was obtained over Ni/Ba–Al2O3 under optimized conditions. Moreover, the catalyst is recyclable and reusable at least four times without significant loss of the conversion of furfural and selectivity of THFA.

Catalytic conversion of 5-hydroxymethylfurfural into 2,5-furandiamidine dihydrochloride

Via implantation of nitrogen from aq. NH3 into hydroxymethylfurfural (HMF), dimethyl furan-2,5-dicarboximidate was synthesized over a manganese oxide catalyst. It was realized by the ammoxidation of HMF followed by methanol addition under mild reaction conditions. The imidate prepared in situ was further transformed into 2,5-furandiamidine dihydrochloride by reaction with ammonium chloride.

A High-Performance Base-Metal Approach for the Oxidative Esterification of 5-Hydroxymethylfurfural

Exploring high‐performance base‐metal approaches for the sustainable production of chemicals from biomass is presently attracting immense interest and is truly important to promote their industrialized application. Herein, CoOx‐N/C and α‐MnO2 were combined as a base‐metal catalyst that can achieve high yields of furan‐2,5‐dimethylcarboxylate (FDMC, 95.6 %) for the catalytic oxidative esterification of 5‐hydroxymethylfurfural (HMF) without basic additive. The reaction proceeds through fast conversion of HMF to diformylfuran (DFF) with α‐MnO2 and subsequent transformation of DFF to FDMC by CoOx‐N/C. Quantitative X‐ray photoelectron spectroscopy (XPS) analysis and density functional theory (DFT) calculations indicated that the pyridinic‐N present in doped carbon could behave as a Lewis base to promote the abstraction of hydrogen for the oxidative esterification reaction. Consequently, CoOx‐N/C is a high performance catalyst for the synthesis of FDMC from DFF in a neutral medium.

Alkali α-MnO2/NaxMnO2 collaboratively catalyzed ammoxidation–Pinner tandem reaction of aldehydes

The tandem reaction is a growing field to yield important advances toward green and sustainable chemistry. Herein, we report a bifunctional manganese oxide catalyst with an interface binding redox phase (α-MnO2) and a basic phase (NaxMnO2). The molar ratio of NaOH/Mn plays a great role in the formation of α-MnO2/NaxMnO2. The sodium cation is essential for the formation of a basic NaxMnO2 phase while the potassium cation promotes the formation of a redox-active α-MnO2 phase. The interface structure of α-MnO2/NaxMnO2 geometrically favors the ammoxidation–Pinner tandem reaction to synthesize imidates in a 58–96% yield from aldehydes. Thus a phase collaborative effect is observed. In the ammoxidation process, the redox cycle of MnIV/MnIII is involved and the lattice oxygen in the α-MnO2 phase acts as an active oxygen species. The O–H in methanol is activated and dissociated on the basic sites of NaxMnO2 to the adsorbed methoxyl species to facilitate the Pinner synthesis. This approach bypasses the conventional synthesis of imidates, which suffer from harsh reaction conditions and the requirement for multiple steps.

Carboxylic acid-modified metal oxide catalyst for selectivity-tunable aerobic ammoxidation

Controlling the reaction selectivity of a heterobifunctional molecule is a fundamental challenge in many catalytic processes. Recent efforts to design chemoselective catalysts have focused on modifying the surface of metal nanoparticle materials having tunable properties. However, precise control over the surface properties of base-metal oxide catalysts remains a challenge. Here, we show that green modification of the surface with carboxylates can be used to tune the ammoxidation selectivity toward the desired products during the reaction of hydroxyaldehyde on manganese oxide catalysts. These modifications improve the selectivity for hydroxynitrile from 0 to 92% under identical reaction conditions. The product distribution of dinitrile and hydroxynitrile can be continuously tuned by adjusting the amount of carboxylate modifier. This property was attributed to the selective decrease in the hydroxyl adsorption affinity of the manganese oxides by the adsorbed carboxylate groups. The selectivity enhancement is not affected by the tail structure of the carboxylic acid.Precisely controlling the surface properties of base-metal oxide catalysts to tune the reaction selectivity remains a challenge. Here, the authors show that a green modification of manganese oxide surface with carboxylates can be used to tune the ammoxidation selectivity toward the desired products.

Selective synthesis of 2,5-bis(aminomethyl)furan via enhancing the catalytic dehydration–hydrogenation of 2,5-diformylfuran dioxime

2,5-Bis(aminomethyl)furan as a promising monomer was efficiently synthesized in 94.1% yield from biomass-derived 2,5-diformylfuran dioxime. The high selectivity is likely to be a result of the controlled reaction pathway over Rh/HZSM-5, which enhanced the sequence of the dehydration–hydrogenation of 2,5-diformylfuran dioxime owing to the surface acidity on the HZSM-5 support.