Renchun Yang

PEG1000-Based Dicationic Acidic Ionic Liquid as an Efficient Catalyst for Mannich-Type Reaction in Water

Abstract PEG1000-based dicationic acidic ionic liquid (PEG1000-DAIL) was found to be an efficient and recyclable catalyst for Mannich-type reaction of different ketones with various aromatic aldehydes and aromatic amines in water to give various β-arylamino ketones in good yields. The catalytic system could be easily recovered and reused for at least six runs only with slight decrease in its activity. GRAPHICAL ABSTRACT

Synthesis of Fe3O4/P(St-AA) nanoparticles for enhancement of stability of the immobilized lipases

Core–shell Fe3O4/P(St-AA) (Fe3O4/polystyrene–poly acrylic acid) nanoparticles modified with carboxylic acid groups were synthesized and employed as magnetic carriers for Candida rugosa lipase (CRL) and porcine pancreas lipase (PPL) immobilization. The loading amount of CRL on the Fe3O4/P(St-AA) nanoparticles was calculated to be 87.7 mg protein per g particles. Effects of solution pH and reaction temperature on the relative activity of immobilized CRL were measured and compared with the free CRL. The hydrolytic kinetics of the free and immobilized CRL was also investigated. Hydrolytic activity tests indicated that the stability of the immobilized CRL was strengthened. It should be mentioned that the immobilized CRL retained more than 56.1% of its initial activity after reuse 10 times. Most importantly, the immobilized PPL can tolerate organic media and maintain high esterification activity in n-hexane solution. This work provided a facile and general approach to synthesize magnetic functional nanocomposites for applications in biological and biocatalytic fields.

Improved performance of immobilized lipase by interfacial activation on Fe3O4@PVBC nanoparticles

An effective strategy for enhancement of catalytic activity and stability of immobilized lipase by interfacial activation on Fe3O4@PVBC (Fe3O4@polyvinylbenzyl chloride) nanoparticles was developed, which involved the fabrication of core–shelled Fe3O4@PVBC nanoparticles via an emulsion polymerization process and the subsequent immobilization of lipase in phosphate buffer. Due to the magnetic nature of Fe3O4 cores and the presence of chloromethyl-functionalized polymer shells, the Fe3O4@PVBC nanoparticles were employed as valid magnetic carriers for lipase immobilization. Bradford assays indicated that the loading amount of lipase on the Fe3O4@PVBC nanoparticles was calculated to be 162.5 mg protein per g particles. The catalytic activity of the immobilized lipase retained about 99.6 ± 3.3% of the free enzyme activity, which was attributed to interfacial activation of lipase by Fe3O4@PVBC nanoparticles. Thermal and urea tolerance tests revealed that the immobilized lipase exhibited much better stabilities. Additionally, the immobilized lipase retained more than 69.8% of its initial activities after 10 times of reuse. It is believed that the results of the present investigation may provide a versatile approach for designing and fabricating biocatalysts with high activation and stability.

Three-dimensionally ordered macroporous LaMnO3 with tunable oxygen vacancies via nitric acid-aided modulating and their catalytic combustion properties

Three-dimensionally ordered macroporous (3DOM) LaMnO3 oxides with tunable oxygen vacancies have been successfully fabricated via a facile nitric acid-aided modulating sol–gel method. The morphology, composition, pore structure and reducibility of the prepared catalysts were characterized by XRD, EDS, FE-SEM, XPS, TPR, and N2 adsorption–desorption. The results indicate that the oxygen vacancies contents of the as-prepared catalysts are heavily dependent on the amount of nitric acid. Among the three LaMnO3 catalysts, the LaMnO3-C sample shows the highest oxygen vacancies content and the better low-temperature reducibility. These findings reveal that the introduction of a little amount of nitric acid can effectively promote the formation of oxygen vacancies, ultimately resulting in an enhanced catalytic oxidation activity for ethyl acetate oxidation.

Study of the Surface Oxygen Vacancies Evolvement on the Single and Bi-Components Manganese Oxide Precursors and their Catalytic Performance

AbstractTo study the oxygen vacancies evolvement on the single component and the bi-components manganese oxides, two manganese oxide precursors (Mn5O8 and MnO2–Mn3O4) with similar Mn/O ratio were prepared and were treated by air, N2, and Ar, respectively. The morphology, composition and structure of the prepared samples were characterized by FE–SEM, XRD, XPS, EPR, STEM, STEM-EDS and N2 adsorption–desorption. The valence state evolvement indicates that the Mn5O8 and MnO2–Mn3O4 are all transformed into MnO, Mn3O4 and MnO1.88 with different proportions. The results showed that the oxygen vacancies contents of the as-prepared samples are not only related to the treating atmosphere but also heavily dependent on the atom ratios of Mn and O of the precursors. Compared with the heat treated MnO2–Mn3O4, the heat treated Mn5O8 presented higher oxygen vacancies content and more Mn atoms dislocating structure, suggesting that the single component Mn5O8 is helpful to promoting the formation of defects. These findings reveal that the single component Mn5O8 is helpful to the formation of oxygen vacancies, ultimately resulting in an enhanced catalytic combustion performance of toluene.Graphical AbstractThe oxygen vacancies evolvement of the single component and the bi-components manganese oxides were explored. Compared with the nanorods-Ar, the spindles-Ar shows more oxygen vacancies and dislocating Mn atoms, and enhanced catalytic combustion performance of toluene.

Efficient method for the synthesis of 3-arylbenzoquinoline, pyranoquinoline, and thiopyranoquinoline derivatives using PEG1000-based dicationic acidic ionic liquid as recyclable catalyst via a one-pot multicomponent reaction

ABSTRACT A series of 3-arylbenzoquinoline, pyranoquinoline, and thiopyranoquinoline derivatives have been synthesized by one-pot, multicomponent reaction of aromatic aldehyde, naphthalen-2-amine, and ketone using polyethylene glycol (PEG1000)–based dicationic acidic ionic liquid as recyclable catalyst with high yields. The PEG ionic liquid and toluene have the advantages of both homogeneous and heterogeneous phases at different temperatures (biphasic conditions at lower temperatures and monophasic at higher temperatures) with the ease of product as well as catalyst separation. Recycling studies have shown that the ionic liquid can be readily recovered and reused several times without significant loss of activity. GRAPHICAL ABSTRACT

Effect of Interface Contact Between C and C 3 N 4 on Photocatalytic Water Splitting

The contact form of the heterojunction interface has an importance effect on interfacial photoelectron transfer and photocatalytic property. Here, C/C3N4 heterojunction with three types of interface contact between C and C3N4 have been constructed, including C/C3N4-I, C/C3N4-HI, C/C3N4-D. The physico-chemical properties of the prepared catalysts were characterized by TEM, XRD, XPS, Raman, FT-IR, UV–VIS DRS and UPS. The results indicate that the interface composition (Cg/Cs, Nt/Ns) and valence band characteristic of the photocatalysts are strongly dependent on the interface contact form of C and C3N4. Compared with the C/C3N4-HI and C/C3N4-D, the sample C/C3N4-I present higher ratios of Cg/Cs and Nt/Ns, stronger light response and appropriate band locations. These findings reveal that the C deposited on the surface of C3N4 promotes the efficiencies of light harvest and charge carrier separation, ultimately resulting in an enhanced photocatalytic performance for pure water splitting.Graphical Abstract