查找使用阿拉丁产品的科研文献

Effect of Lewis and Brønsted acidity in Ni/ZSM-5 on catalytic reductive etherification of furfural and alcohols

Mengxue Song,Chonghao Qiu,Pengfei Ma,Jiawei Zhong,Zhuohan Zhang,Weiping Fang,Wenjing Song,Jianqiang Fan,Weikun Lai

Reductive etherification is an attractive and practical strategy to convert bio-platform compounds into valuable chemicals. In directed synthesis of furfuryl ethers, reductive etherification of bioderived furfurals is still challenging due to the complexity of catalytic reaction . Herein, reductive etherification of furfural with alcohol was investigated over Ni/ZSM-5 catalyst, which found that Si/Al ratios in ZSM-5 played an important role on the catalytic performance. For Ni/ZSM-5 with Si/Al ratio of 50, 80.9% yield of furfuryl ether at 90.8% conversion of furfural was achieved under the condition of 2 MPa H 2 and 180 °C for 3 h in isopropanol. The catalyst exhibited superior stability and recyclability during the consecutive cycle run. Catalysts characterization demonstrated that both acidic properties and furfural adsorption were influenced by the Si/Al ratios in Ni/ZSM-5, which correlated to the reaction route and catalytic performance. Lewis acid sites enhanced furfural hydrogenation into furfuryl alcohol, while Brønsted acid sites on ZSM-5 effectively catalyzed sequential etherification of furfuryl alcohol to furfuryl ether. Under optimization conditions, various furfuryl ethers could be obtained with yields above 80% over Ni/ZSM-5 catalyst in different primary alcohols, demonstrating the general versatility of the approach. Our findings offered opportunities to develop an efficient furfuryl ethers synthesis method .

Soluplus-stabilized 5-fluorouracil-entrapped niosomal formulations prepared via active and passive loading techniques: comparative physico-chemical evaluation

Onyinyechi Lydia Ugorji,Olisa Ivy Okoye,Chinekwu Nwangwu,Chinazom Precious Agbo,Franklin Chimaobi Kenechukwu

Preparation of 2,5-furandicarboxylic acid from carbohydrates via 5-acetoxymethylfurfural as intermediate in a single acetic acid system

Lu Yanyu,Lin Changqu,Yang Hao,Ma Peipei,Chen Jishuang,He Zhuang,Wu Hongli,Cao Fei,Chen Kequan,Ouyang Pingkai

Abstract FDCA (2,5-furandicarboxylic acid), produced by oxidizing carbohydrate-derived HMF (5-hydroxymethylfurfural), is a valuable monomer for biopolymers. The difference in the solvent system between the dehydration reaction and oxidation reactions seriously affects the process continuity and production efficiency. Herein, we reported a cascade process for FDCA production from carbohydrates in a single acetic acid system. The fructose conversion was complete and total furan compounds yield reached nearly 90%, which contained 42.8% HMF and 47.1% 5-acetoxymethylfurfural (AMF) in the acetic acid system with NaBr addition. After the azeotropic distillation and vacuum distillation in situ, AMF, a more stable intermediate than HMF, could be easily collected with 90.5% recovery and 99.9% purity. AMF was also oxidized into FDCA with 91.1% yield by Co/Mn/Br catalysts in the acetic acid system. Finally, the cascade process, including fructose dehydration–esterification and HMF/AMF mixture oxidation, was successfully realized in a single acetic acid system. This process is simple to operate, easy to implement, eliminates the use of extra acid or self-made catalysts and expensive solvents, and has the potential for continuous preparation from carbohydrates to FDCA. Graphical Abstract

Bifunctional catalyst of CuMn-HZSM-5 for selective catalytic reduction of NO and CO oxidation under oxygen atmosphere

Yangyang Guo,Yang Zheng,Yue Peng,Tao Yue,Tingyu Zhu

Simultaneous removal of NO x and CO from steel sintering has attracted great attention because it is difficult to balance the catalyst reducibility and surface acidity merely using metal oxides or zeolite catalysts. In this study, a mixed CuMn-HZSM-5 catalyst was prepared via an impregnation method. The optimized sample exhibited excellent performance with 90% NO conversion and 100% CO conversion at 175 °C. The activity window of the catalyst was coincident with the actual demand of sintering flue gas control at 150-250℃. The active component CuMn suppressed the excessive Lewis acid sites on the zeolite support for NH 3 adsorption, while the reducibility of the catalyst also decreased compared with that of pure CuMn metal oxides . This synergistic effect was beneficial for the reduction of NH 3 nonselective oxidation with O 2 . In addition, both the DFT and DRIFTS results revealed that NO conversion was improved by CO introduction at low temperature, since NO could adsorb on the CO-preadsorbed sites for the reduction to N 2 via the O atoms of Mn 3c sites, i.e., adsorbed CO could also serve as a reductant to reduce NO to N 2 , which provides another reaction pathway in SCR reactions. Moreover, the NO 2 − and N 2 O 2 − species were observed in the spectra as key intermediates to oxidize CO to CO 2 , which are also the promoters for CO control.

Preparation, separation and purification of 5-hydroxymethylfurfural from sugarcane molasses by a self-synthesized hyper-cross-linked resin

Xue-fang Chen,Hai-long Li,Xu-ran Ji,Zhi-jie Shen,Hai-jun Guo,Shi-miao Yao,Meng-kun Wang,Lian Xiong,Xin-de Chen

Sugarcane molasses is a by-product in the process of sugar production, which has characteristics of large quantity, low price and easy to pollute the environment. High-valued utilization of sugarcane molasses has important research significance. In this work, 5-hydroxymethylfurfural (HMF) was obtained through hydrolyzing sugarcane molasses, and was separated from the hydrolysate by a designed hyper-cross-linked adsorption resin (HCLR). The optimal conditions for adsorption/desorption of HMF by HCLR were obtained. On this basis, the adsorption kinetics, equilibrium and thermodynamic behavior of HMF onto HCLR were studied, and the adsorption mechanism of HMF onto HCLR was clarified. At last, HMF with a highest purity of 96.0% and an average purity of 93.2% were obtained through fixed bed dynamic adsorption/desorption study. Overall, this work provides a complete process route from sugarcane molasses to high-value product of HMF, and provides theoretical and technical references for the efficient and comprehensive utilization of sugarcane molasses resources.

Hierarchical VAPO-5 Catalysts Prepared from Different Vanadium Sources in Fluoride Medium and Their Performance in Toluene Oxidation

Zhang Jian,Ma Yongwei,Shao Hui

Abstract Hierarchical VAPO-5 molecular sieves were prepared with different vanadium resources in the absence/presence of fluorine and characterized by XRD, SEM, N 2 adsorption-desorption, and NH 3 -TPD. The catalytic performances of hierarchical VAPO-5 molecular sieves were evaluated using toluene oxidation as the probe reaction and the corresponding mechanism was further proposed. The sample D-AFI-2(F) synthesized in a fluorine system with NH 4 VO 3 as metal sources show better catalytic performance than other samples in toluene oxidation, which is ascribed to the hierarchically porous structure and more acidic sites. The optimized condition of toluene oxidation was attained at the reaction temperature of 60°C, the reaction time of 5 h, the molar ratio of H 2 O 2 to toluene 2 : 1, the mass ratio of acetonitrile to toluene 6 : 1, and the mass ratio of catalyst to toluene 10%. In this case, the toluene conversion was 21.0%, and the selectivity of benzaldehyde, benzyl alcohol, and cresol was 43.3, 11.4, and 26.2%, respectively.

Multiple Physically Cross-Linked F127−α-CD Hydrogels: Preparation, Sol–Gel Transformation, and Controlled Release of 5-Fluorouracil

Peihong Li,Chunling Zhang,Rui Li,Lijie Qu,Xueyan Dai,Yanlong Sui,Jiazi Hou

Pluronic F127 is a thermosensitive polymer that has been extensively studied and utilized in biomedicine. To improve the gelation properties of F127, α-cyclodextrin was introduced by physical interactions, such as forming inclusion complexes, hydrogen bond self-assembly, and hydrophobic interactions, to prepare F127−α-CD hydrogels. This study explored the temperature-dependent sol–gel transition behavior, gelation mechanism, interior morphology, and controlled release of the anticancer drug 5-fluorouracil. Results showed that hydrogel could be obtained at 1.0%–8.0% weight content of F127. The cross-linking points in this system were PEO−α-CD microcrystalline region and micelle with poly(propylene oxide) as the core. The network inside F127−α-CD hydrogels made it stable and conducive for controlled release. Therefore, this hydrogel is a promising drug release system.

Non-Volatile Glycerin Gel Enhanced by Sub-5 nm Particles with Super Elasticity, Recoverability, and High Temperature Resistance

Lefan Li,Qiao Wang,Zongjin Li,Siyao Guo,Guoxing Sun

A gel material that can be applied to industry needs to fulfill two requirements: excellent mechanical properties and high temperature resistance. Previous research developed a hydrogel enhanced by sub-5 nm particles, with excellent mechanical properties. While its application in the open environment is still limited by the volatilization of inner moisture, in this research, a non-volatile gel (NV gel) enhanced by 5-nm spherulites is manufactured. The NV gel remains stable after staying at 90 °C for 24 h. Meanwhile, being enhanced by sub-5 nm nanospherulites, the NV gel shows good mechanical properties: with 200 ppm nanoparticle content, the tensile strength reaches 814 kPa and the compressive stress is 173.41 MPa at a recoverable 99% strain. The high temperature resistance is characterized by thermogravimetric analysis (TGA) and mechanical testing after thermal treatment. Transmission electron microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy, time of flight secondary ion mass spectrometry, and thermogravimetric analysis are used to evaluate the microstructure of NV gel. Possessing non-volatile and good mechanical properties at the same time, this NV gel becomes very suitable for fulfilling the application requirement as an engineering material.

Synthesis and multi-electrochromic properties of asymmetric structure polymers based on carbazole-EDOT and 2, 5–dithienylpyrrole derivatives

Bin Hu,Chunyang Li,Zengchen Liu,Xinlei Zhang,Wen Luo,Lin Jin

Two novel asymmetric structure monomers , 3,6-Bis-(2,3-dihydro-thieno[3,4- b][1,4]dioxin-5-yl)-9-[4-(2,5-di-thiophen-2-yl-pyrrol-1-yl)-phenyl]-9H-carbazole (BDTC) and 2,7-Bis-(2,3-dihydro-thieno[3,4-b][1,4]dioxin-5-yl)-9-[4-(2,5-di-thio phen-2-yl-pyrrol-1-yl)-phenyl]-9H-carbazole (BDDC), were designed and synthesized. Both the monomers could be electropolymerized to form the related polymer films. The electrochemical and electrochromic properties of polymer films were different from that of their homopolymers , which could be attributed to the similar copolymerization effect of asymmetric structure. Different linked positions also led to different features, PBDDC film showed more colors (orange, yellow green, green and blue) than that of PBDTC film (yellow, green and purple blue). However, after the introduction of 2, 2′-Bi(3,4-ethoxylene dioxy thiophene)(BIEDOT), the resulting copolymers exhibited similar electrochromic features(red, brown yellow, green and blue) due to the leading effect of EDOT units. Moreover, all the polymer films displayed fast switching time, reasonable optical contrast and good coloration efficiency, which made them have potential application in electrochromic devices.

PdCl2-catalyzed hydrodeoxygenation of 5-hydroxymethylfurfural into 2,5-dimethylfuran at room-temperature using polymethylhydrosiloxane as the hydrogen donor

Jun Zhang,Kaijun Dong,Weimin Luo

A facile and mild method for the catalytic production of 2,5-dimethylfuran (DMF) from 5-hydroxymethylfurfural (HMF) was developed, which utilized commercial PdCl 2 as the catalyst together with the green, non-toxic and low-cost hydride source, polymethylhydrosiloxane (PMHS). A synergistic effect among hydrogen donor, in situ generated metallic Pd 0 species and acid site HCl in the reaction played a key role in DMF formation. Gratifyingly, the desirable yield of hydrodeoxygenation product DMF as high as 89.7% from HMF was attained at room temperature (298 K) in 0.5 h. Meanwhile, biomass derived sugars also could be converted into DMF in relative high efficiency via a one-pot reaction in the present system. A plausible pathway for the hydrodeoxygenation of HMF into DMF in the present system was also proposed. The study thus highlights a new perspective for a simple, green, and efficient hydrodeoxygenation of biomass derivatives under milder conditions, employing a readily available, inexpensive and practical catalytic system of PdCl 2 -PMHS-ethanol, but without any external hydrogen supplies and pre-reduction treatments.

Amplified electrochemical immunoassay for 5-methylcytosine using a nanocomposite prepared from graphene oxide, magnetite nanoparticles and β-cyclodextrin

Zhou Yunlei,Jiang Wenjing,Wu Hanwen,Liu Fei,Yin Huanshun,Lu Nan,Ai Shiyun

A nanocomposite was prepared from β-cyclodextrin (β-CD) functionalized graphene oxide and magnetic nanoparticles (GO/Fe 3 O 4 /β-CD). In parallel, a polyamidoamine dendrimer conjugated to avidinylated alkaline phosphatase (PAMAM-avidin-ALP) was prepared and exploited as a signal amplification unit in a voltammetric immunoassay for 5-methylcytosine (5mC) in genomic DNA. The GO/Fe3O4/β-CD as a substrate material exhibited good solubility, electrical conductivity and large surface. This is beneficial for the further modification of antibodies (Ab) by host-guest interaction and amide bonds. By taking advantage of three-dimensional structure to capture avidin-ALP by amide linkages, PAMAM was used as a catalytic signal amplification element in this assay. Under the optimized condition and at a typical working potential of 0.94 V, the response to 5mC is linear in the 0.01–50 nM concentration range with a detection limit of 3.2 pM (at S/ N  = 3). The method is stable, selective and reproducible. It was applied to the determination of 5mC in genomic DNA of human tissue. An electrochemical immunoassay was constructed for 5-methylcytosine detection based on nanocomposite of graphene oxide, magnetite nanoparticles and β-cyclodextrin, and enzymatic signal amplification.

Interface synergy between IrOx and H-ZSM-5 in selective C–O hydrogenolysis of glycerol toward 1,3-propanediol

Xiaoyue Wan,Qi Zhang,Mingming Zhu,Yi Zhao,Yongmei Liu,Chunmei Zhou,Yanhui Yang,Yong Cao

Site-selective deoxygenation of hydroxyl groups represents essential processes to access valuable functionalized bio-based compounds with industrial potential. One of the challenging tasks in this context is to convert biodiesel-derived glycerol in the presence of abundant water directly to 1,3-propanediol (1,3-PDO), a key component of the emerging polymer industry. Herein, a monometallic iridium supported on H-ZSM-5 in the absence of Re oxophilic metal oxides was prepared via grinding-assisted impregnation procedures and attempted as an effective and recyclable catalyst for the aqueous-phase selective hydrogenolysis of glycerol toward 1,3-PDO in the absence of acid additives. The results revealed the necessity to control the Ir domain dispersions, Ir 0 /Ir 3+ ratio and the amounts of overall acid/Brönsted acid sites. Activity depended linearly on the amount of overall and Brönsted acid sites, and 1,3-PDO selectivity increased in the presence of Ir-induced Brönsted acid sites, denoted as Ir-O(H)-H-ZSM-5. We speculate that Ir-O(H)-H-ZSM-5 are generated by the interfacial synergistic interaction between IrO x and H-ZSM-5 through hydrogen spillover and reverse hydrogen spillover according to the reported literatures. The reaction mechanism to elucidate the role of Ir-O(H)-H-ZSM-5 sites in glycerol hydrogenolysis was also postulated based on extensive characterization and catalytic reaction results.