介孔负载维生素B_1催化合成双糠醛

通过自制氧化硅介孔材料,采用浸渍蒸发法制得介孔负载维生素B1催化剂,并应用于糠醛催化合成双糠醛。产物双糠醛采用红外光谱、核磁共振氢谱、紫外光谱表征。实验结果表明催化剂制备简单、催化活性高、产品收率高、后处理简便、无三废污染、符合节能环保、绿色催化的要求。

Efficient production of 5-hydroxymethylfurfural from hexoses using solid acid SO_4^(2-)/In_2O_3-ATP in a biphasic system

A natural attapulgite （ATP）‐based catalyst, sulfated In2O3‐ATP （SO42-/In2O3‐ATP）, was obtained by an impregnation‐calcination method and was used to efficiently and selectively produce the useful platform chemical 5‐hydroxymethylfurfural （HMF） from hexoses. Some important reaction param‐eters were studied, revealing that Lewis and Br-nsted acid sites on SO42-/In2O3‐ATP catalyze glu‐cose isomerization and fructose dehydration. The yields of HMF from glucose and fructose were 40.2%and 46.2%, respectively, using the optimal conditions of 180℃ for 60 min with 10 wt%of solid acid catalyst in a mixture of γ‐valerolactone‐water （9：1）.

Influence of supports for selective production of 2,5-dimethylfuran via bimetallic copper-cobalt catalyzed 5-hydroxymethylfurfural hydrogenolysis

The hydrogenolysis of carbon–oxygen bonds is an important model reaction in upgrading biomass‐derived furanic compounds to transportation fuels.One of these model reactions,namelyconversion of5‐hydroxymethylfurfural(HMF)to the gasoline additive2,5‐dimethylfuran(DMF),isespecially attractive.In this study,bimetallic Cu‐Co catalysts supported on CeO2,ZrO2,and Al2O3were used for the selective hydrogenolysis of HMF to DMF.The structures of the fresh and usedcatalysts were studied using X‐ray diffraction,the Brunauer‐Emmett‐Teller method,transmissionelectron microscopy,temperature‐programmed reduction by H2,temperature‐programmed desorptionof NH3,and CHNS analysis.The structures were correlated with the catalytic activities.TheCu‐Co/CeO2catalyst produced mainly2,5‐bis(hydroxymethyl)furan via reduction of C=O bonds onlarge Cu particles.The Cu‐Co/Al2O3catalyst gave the best selectivity for DMF,as a result of a combinationof highly dispersed Cu,mixed copper–cobalt oxides,and suitable weak acidic sites.Cu‐Co/ZrO2had low selectivity for DMF and produced a combination of variousover‐hydrogenolysis products,including2,5‐dimethyltetrahydrofuran and5,5‐oxybis(methylene)‐bis(2‐methylfuran),because of the presence of strong acidic sites.The reaction pathways and effectsof various operating parameters,namely temperature,H2pressure,and time,were studied to enableoptimization of the selective conversion of HMF to DMF over the Cu‐Co/Al2O3catalyst.

Selective tandem hydrogenation and rearrangement of furfural to cyclopentanone over CuNi bimetallic catalyst in water

Tandem catalysis for the hydrogenation rearrangement of furfural(FA)provides an attractive solution for manufacturing cyclopentanone(CPO)from renewable biomass resources.The Cu-Ni/Al-MCM-41 catalyst was synthesized and afforded excellent catalytic performance with 99.0%conversion and 97.7%selectivity to CPO in a near-neutral solution under 2.0 MPa H2 at 160℃ for 5 h,much higher than those on other molecular sieve supports including MCM-41,SBA-15,HY,and ZSM-5.A small amount of Al highly dispersed in MCM-41 plays an anchoring role and ensures the formation of highly dispersed CuNi bimetallic nanoparticles(NPs).The remarkably improved catalytic performance may be attributed to the bimetallic synergistic and charge transfer effects.In addition,the initial FA concentration and the aqueous system pH required precise control to minimize polymerization and achieve high selectivity of CPO.Fourier transform infrared spectroscopy and mass spectra results indicated that polymerization was sensitive to pH values.Under acidic conditions,FA and intermediate furfuryl alcohol polymerize,while the intermediate 4-hydroxy-2-cyclopentenone mainly polymerizes under alkaline conditions,blocking the cascade of multiple reactions.Therefore,near-neutral conditions are most suitable for minimizing the impact of polymerization.This study provides a useful solution for the current universal problems of polymerization side reactions and low carbon balance for biomass conversion.

Correlation between 5-hydroxymethylfurfural content and color of Rehmanniae Radix and Rehmanniae Radix Praeparata

In the present study,we explored the correlation between 5-hydroxymethylfurfural(5-HMF)and color of Rehmanniae Radix(RR)and Rehmanniae Radix Praeparata(RRP).The color was observed by human eyes under sunlight.The chromatic value and color difference were detected by a colorimeter.The water content was determined by an oven-drying method.The 5-HMF content was determined by an HPLC method.The correlation between the 5-HMF content and the color was analyzed by bivariate correlation analysis.The results showed that the color was greyish-brown and dark brown for RR,and it was black for RRP.The deepening color of RRP was reflected in the decrease of L^*,a^*and b^*values.The water content was in accord with the requirement of Chinese Pharmacopoeia.The 5-HMF contents of RR and RRP were 0.9711–25.71μg/g and 213.4–4010μg/g,respectively.The average 5-HMF contents of RR and RRP were 8.059μg/g and 1433μg/g,respectively.The 5-HMF content in RRP was higher than that in RR.The correlations between 5-HMF content and L^*,a^*and b^*values were significant.The color of RRP was deeper than that of RR.The 5-HMF content of RRP was higher than 0.02%,while it was less than 0.02%of RR,which could be used as a marker component for judging RR and RRP.