Activation of formyl CH and hydroxyl OH bonds in HMF by the CuO(1 1 1) and Co₃O₄(1 1 0) surfaces: A DFT study

Ren, Jun,Song, Kai-he,Li, Zhenhuan,Wang, Qiang,Li, Jun,Wang, Yingxiong,Li, Debao,Kim, Chan Kyung Elsevier 2018 APPLIED SURFACE SCIENCE - Vol.456 No.-

<P><B>Abstract</B></P> <P>The first principle calculations with on-site Coulomb repulsion U terms were carried out to investigate the 5-hydroxymethylfurfural (HMF) adsorption on the CuO(1 1 1) and Co<SUB>3</SUB>O<SUB>4</SUB>(1 1 0) surfaces, two widely used oxidation catalysts. The adsorption of HMF molecule is energetically favoured in both cases, and HMF is more inclined to bridge adsorption via hydroxyl and formyl groups binding with surface O and metal sites. Moreover, the adsorption energy relies on both the coordination type of surface lattice oxygen to which the H atom binds and the formation of H-bond involving hydroxyl and formyl groups on the adsorbed HMF. Also, the hydroxyl OH bond breaking is very easy and is likely to be the first step in HMF oxidation, and then the OH insertion reaction to produce 2,5-furandicarboxylic acid (FDCA). The corresponding experimental results also show that the CuO and Co<SUB>3</SUB>O<SUB>4</SUB> surfaces are promising candidate catalysts.</P> <P><B>Highlights</B></P> <P> <UL> <LI> CuO(1 1 1) and Co<SUB>3</SUB>O<SUB>4</SUB>(1 1 0) surfaces catalyze the oxidation of 5-hydroxymethylfurfural (HMF). </LI> <LI> Initial binding was formed through bridged-adsorption with O atoms in HMF. </LI> <LI> Oxidation reaction proceeds through the OH bond breaking pathway. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>Schematic potential energy diagram for the formyl CH and hydroxyl OH bonds of HMF dissociation on CuO(1 1 1) and Co<SUB>3</SUB>O<SUB>4</SUB>(1 1 0) surfaces. Obviously, the hydroxyl OH bond breaking is easier than that of the formyl CH bond on the two surfaces, which indicates the first step of oxidation of HMF to FDCA should be hydroxyl OH bond breaking.</P> <P>[DISPLAY OMISSION]</P>

Direct catalytic conversion of glucose and cellulose

Li, Zhenhuan,Su, Kunmei,Ren, Jun,Yang, Dongjiang,Cheng, Bowen,Kim, Chan Kyung,Yao, Xiangdong The Royal Society of Chemistry 2018 GREEN CHEMISTRY Vol.20 No.4

<P>Biomass product 5-hydroxymethylfurfural (5-HMF) can be used to synthesize a broad range of value added compounds currently derived from petroleum. Thus, the effective conversion of glucose or cellulose (the major components of biomass) into fuels and chemical commodities has been capturing increasing attention. Previous studies have been extensively focused on a two-step process for producing 5-HMF from glucose or cellulose, <I>i.e.</I>, the isomerization of glucose into fructose and then the dehydration of fructose. We herein discovered that heterogeneous sulfonated poly(phenylene sulfide) (SPPS) containing strong Brønsted acid sites is able to convert glucose and cellulose into 5-HMF with a high yield in ionic liquids (ILs). The optimal activity of glucose conversion to 5-HMF achieves a yield of 87.2% after 4 h reaction at 140 °C. For direct cellulose conversion, a 5-HMF yield of 68.2% can be achieved. The reaction mechanism over the SPPS catalyst in ILs was studied by DFT calculations, and the results indicated that the SO3H group of SPPS plays a crucial role in glucose conversion into 5-HMF, and it acts as a proton donor as a Brønsted acid and functions as a proton acceptor as the conjugate base. Furthermore, the anions and cations of ILs together with SO3H-SPPS helped in stabilizing the reaction intermediates and transition states, which also resulted in glucose facile conversion into 5-HMF. The new catalyst system highlights new opportunities offered by optimizing the production of 5-HMF directly from glucose and cellulose.</P>

A Superhydrophilic and Anti-Biofouling Polyphenylene Sulfide Microporous Membrane with Quaternary Ammonium Salts

Chao Wang,Zhenhuan Li,Lei Cao,Bo-wen Cheng 한국고분자학회 2018 Macromolecular Research Vol.26 No.9

Polyphenylene sulfide (PPS) membranes were modified by chloromethylation and quaternary amination reaction to prepare a hydrophilic PPS microporous membrane. The structures of the modified PPS membranes were characterized by the use of Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The results showed that the modified membranes maintain the same microporous structures as the PPS membrane. The hydrophilicity of the modified membranes was significantly improved compared to that of the PPS membranes, and the water flux of N-methylimidazole modified membranes, triethylamine modified membranes, and both mixture modified membranes achieved 110.475, 168.94, 150.59 L·m-2·h-1, respectively. The quaternary amination of the PPS membranes made much less bovine serum albumin (BSA) pollution accumulation on the top surface of the modified membranes, and there was a significant improvement, to 94%, in the BSA rejection rate. Most importantly, the antibacterial activity of the modified membranes was effectively improved, and the bactericidal rate was elevated to above 80% in comparison with pure PPS membranes, which was attributed to the introduction of quaternary ammonium salts and imidazolium salts in out-surface of the membranes.

The structure of organotin oxides playing a key role on the transesterification of dimethyl carbonate with hydrogenated bisphenol A

Ranran Xia,Zhenhuan Li,Bo-wen Cheng,Kunmei Su 한국화학공학회 2014 Korean Journal of Chemical Engineering Vol.31 No.3

Transesterification of dimethyl carbonate (DMC) with hydrogenated bisphenol A (HBPA) was studiedover various organotin oxides under pressured condition without removal of by-producing methanol. Bu2SnO displayedhigher activities in HBPA conversion and bis-methylcarbonate of hydrogenated bisphenol-A (BMHBPA) synthesis,and HBPA conversion and BMHBPA selectivity reached 97.4% and 84.0%. However, when Ph2SnO was used as catalyst,HBPA conversion and BMHBPA selectivity decreased to 81.5 and 37.7%. Catalyst steric hindrance significantlyinfluenced HBPA conversion and BMHBPA formation, and π-d interaction between phenyl ring and Sn wasunfavorable for the transesterification of HBPA with DMC. Moreover, the catalytic system was further optimized.

Bio-based POF membrane preparation and its use in dye wastewater treatment

Ruiliang Cao,Kunmei Su,Zhenhuan Li 한국고분자학회 2023 Macromolecular Research Vol.31 No.7

2,5-Furandicarboxylic acid (FDCA) is non-toxic, biodegradable, and structurally similar to aromatic di-acids derived from petroleum (petroleum-based aromatic di-acids). In this paper, the polyamide (POF) of FDCA and 4,4′-diaminodiphenyl ether was synthesized in presence of LiCl and N,N-dimethylformamide, and then the new POF membrane was prepared from POF polymer by non-solvent-induced phase separation (NIPS) method. The surface morphology, roughness, contact angle, and zeta potential of the POF membrane surface were well investigated. The results showed that the POF membrane was a hydrophilic, negatively charged, and hard brittle material with high tensile strength. The effects of different POF concentrations in membrane casting solution on the performance of POF membrane were studied through the characterization of flux and interception. When POF concentration was 20 wt%, the prepared membrane exhibited the best performance in long-term stability test, and the flux was 43.9 L m−2 h−1 bar−1, and the rejection rates of the POF membrane for Evans blue, Congo red, and naphthol green B were 95.6%, 93.7%, and 89%, respectively.

Modification of biomass furan-based PEF copolyester with glycerol

Chengzhi Liu,Dongsheng Zhao,Maliang Zhang,Kunmei Su,Zhenhuan Li 한국고분자학회 2024 Macromolecular Research Vol.32 No.1

In order to solve the problem of low molecular weight in the synthesis of poly(ethylene 2,5-furandicarboxylate) (PEF) copolyester with titanium-based catalysts, this paper introduce an appropriate amount of glycerol (GC) into PEF to branch the straight chain polyester though the transesterification-melt polycondensation method, which solve the problem of low resin viscosity and low molecular weight. The structures of the copolymers were characterized by 1H-NMR and 13C-NMR, and the results showed that the modified PEF copolyesters and poly(ethylene-co-glycerol 2,5-furandicarboxylate) (PEGFs) were successfully prepared. The intrinsic viscosity ([η]) of PEGFs copolyesters was characterized by Ubbelohde viscosity, and the results showed that the copolyester [η] was increased from 0.25 dL/g to 0.755 dL/g. The thermal properties of copolyester were characterized by differential scanning calorimetry and thermo gravimetry, and it was found that the glass transition temperature of PEGFs copolyester increased from 67.8 °C to 89.5 °C, and the maximum pyrolysis rate temperature increased from 386.6 °C to 402.8 °C. We characterized the UV resistance of PEGFs copolyester, and the results showed that PEGFs copolyester could be well degraded under ultraviolet light.