Search

A novel solid acid catalyst (PANEAPF) is developed by immobilization of phosphoric acid on polyacrylonitrile fiber through covalent bonding. Various characterization techniques such as elemental analysis (EA), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), etc. are utilized to confirm the successful grafting and the stability of the fiber catalysts during application. PANEAPF shows high catalytic activity in the acetalization of aldehydes owing to the high utilization efficiency of its functionalized acid sites. In addition, the strong polarity micro-environment in the surface layers of PANEAPF make it highly suitable for catalytic application in both water and alcohol. Furthermore, the fiber catalyst can be applied to the acetalization of aldehydes in a continuous-flow process at room temperature, and shows excellent reactivity and superior recyclability (over 20 times). The many advantages of PANEAPF such as simple preparation, convenient regulation of acid amount, high durability, and eco-friendly process make it very attractive for fixed-bed reactors in the chemical industry. [ABSTRACT FROM AUTHOR]

A new polyacrylonitrile fiber-supported Brønsted acid catalyst has been developed and verified to efficiently (high yield, 10 cycles) mediate Biginelli reactions in ethanol, Pechmann condensations in toluene, Friedel-Crafts alkylations of indoles in water and conversion of fructose in dimethyl sulfoxide (DMSO) and mixed-aqueous system. [ABSTRACT FROM AUTHOR]

• Oriented design, facile synthesis and detailed characterization of the novel bifunctionalized fiber catalyst. • Highly selectively catalytic activity for CO 2 cycloaddition with epichlorohydrin under mild conditions. • Simple separation procedure and excellent recyclability of the fiber catalyst-mediated system. Converting CO 2 into useful chemical materials has uniquely high value in both chemical and resource-oriented sense. In this work, several kinds of bifunctional polyacrylonitrile fiber catalysts were developed and applied to selectively catalyze the fixing of CO 2 with epichlorohydrin. Compared to the synergistic effect, the surface polar effect is the major influence factor for the catalytic activity of the fiber catalyst, which is different from other support catalysts and has been explained detailly in this work. Among the synthesized fiber catalysts, benzylamine and N , N' -dimethyl- N -(4-pyridyl)-1,3-propanediamine (DA) bifunctionalized fiber (PAN BD F) has excellent high catalytic activity for its lower polar microenvironment. Different PAN BD Fs with various benzylamine and DA modified degrees were prepared to inspect the influences of benzylamine and DA amounts on the catalytic activity. PAN BD F (benzylamine and DA modified degrees are 0.93 mmol/g and 0.16 mmol/g, respectively) can complete the reaction of epichlorohydrin and CO 2 (97% conversion) under 0.1 mol% catalyst dosage at 80 °C with a CO 2 balloon. Under very low catalyst amount (0.0125 mol%), it can also effectively catalyze the reaction with 56% conversion and the TOF reaches up to 9333.3 h−1. Furthermore, the fiber catalyst can be reused at least five times which indicates a potential to value-added chemistry. [ABSTRACT FROM AUTHOR]

• Prepare a novel quinine functionalized fiber (PAN QN F) used to asymmetric reaction. • The PAN QN F possess high catalytic activity, enantioselectivity and recyclability. • Asymmetric Michael addition is catalyzed excellently by PAN QN F with ee up to greater than 99%. • (S)-2-amino-4H-pyran derivatives are prepared by PAN QN F with ee greater than 99%. As a new type of catalyst support, polyacrylonitrile fiber (PANF) has diverse advantages in physical and chemical properties. Quinine and its derivatives have been widely used as asymmetric organocatalysts recently. By combining the advantages of PANF and quinine, a novel fiber-based asymmetric catalyst (PAN QN F) was successfully prepared through thiol-ene click reaction and characterized by FTIR, XRD, EA, SEM, TGA and mechanical strength analysis. The PAN QN F exhibited excellent catalytic performance for asymmetric Michael addition of malononitrile to chalcone with ee up to > 99%. Further research revealed that the (S)-2-amino-4 H -pyran derivatives were also successfully prepared using PAN QN F as a catalyst in asymmetric tandem Michael addition-nucleophilic annulation of α -phenylchalcone and malononitrile, and the ee of the tandem reaction can also reach greater than 99%. In addition, as an immobilized catalyst, PAN QN F showed relatively wide temperature tolerance and good recycling performance. Overall, the fiber catalyst has the advantages of easy preparation, high activity, high enantioselectivity, wide reaction temperature range, simple separation and good recyclability, which exhibits great potential for industrial application. [ABSTRACT FROM AUTHOR]

A novel phosphinic acid functionalized polyacrylonitrile fiber (PAN APC F) was prepared and its adsorption properties were investigated. The PAN APC F shows excellent selectivity and efficiency for Hg 2+ in the presence of other common metal ions, viz. Pb 2+ , Cd 2+ , Ag + , Zn 2+ , Cu 2+ , Ni 2+ , Co 2+ , Ca 2+ , Mg 2+ . Adsorption kinetics studies show that PAN APC F quickly captures Hg 2+ and achieves equilibrium within 3 h. In addition, PAN APC F is effective over a wide range of pH values (from 3 to 11). The maximum adsorption capacity for Hg 2+ as calculated by a Langmuir isotherm model was 434 mg g −1 . PAN APC F could also efficiently remove Hg 2+ from practical wastewater and the concentration of Hg 2+ could be decreased as low as 27 ppb, which is below the maximum contamination level of 50 ppb for mercury containing wastewater in China. Furthermore, the PAN APC F can be used to remove Hg 2+ from a flow process with a 99% removal efficiency even after ten cycles. Finally, XPS analysis proved that the P O/P OH and –NH– functional groups play a major role in the adsorption mechanism. [ABSTRACT FROM AUTHOR]

A commercially available synthetic polyacrylonitrile fiber, capable of acting as a novel support for polymer-supported copper catalyst in terminal alkyne homocoupling reactions, is presented. Detailed characterization by inductively coupled plasma (ICP) analysis, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy (SEM) confirmed the changes and stability of the fiber catalyst during the modification and utilization processes. Moreover, the catalytic reactions proceeded at room temperature using air as a green oxidant to afford nearly quantitative yields (95–99%); the fiber catalyst has shown excellent activity and superior recyclability (over 16 cycles); and the procedure is operationally simple and amenable to the gram scale in continuous-flow processing. Furthermore, the prominent features (high strength, good flexibility, etc.) of the polyacrylonitrile fiber make the fiber-supported catalyst very attractive for fixed-bed reactors in the chemical industry. [ABSTRACT FROM AUTHOR]

Graphene oxide is modified by diethylenetriamine through a one-step route to prepare GO-NH(CH 2 ) 2 NH(CH 2 ) 2 NH 2 (GO-DETA), which has primary and secondary amino groups and carboxyl groups. GO-DETA is characterized by Fourier transform-infrared spectrum (FT-IR), X-ray diffraction spectroscopy (XRD), thermo-gravimetric analysis (TGA), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The catalytic performance of obtained GO-DETA is investigated in Knoevenagel condensation and Michael addition in water; the results show it can be used as an efficient and stable catalyst. In addition, it has other features, such as simple preparation, good recyclability and environmental friendliness. [ABSTRACT FROM AUTHOR]

A novel carbohydrazide functionalized polyacrylonitrile fiber (PAN J F) was designed and prepared for removal of furfural from water. Compared with other amino-containing functionalized fibers, the PAN J F fiber exhibits the highest adsorption capacity due to the highest reactivity of carbohydrazide. Batch experiments were performed to explore the influence of pH, initial concentration of furfural, dosage of adsorbent, adsorption time, and temperature on the process of adsorption. Under the optimized condition, the maximum adsorption capacity of PAN J F for furfural reaches 140.4 mg g−1. Kinetic and isothermal curves show that the adsorption process is in accordance with the pseudo-second-order model and the Langmuir isothermal adsorption model. Furthermore, the thermodynamic result indicates that the furfural adsorption on PAN J F is an endothermic and spontaneous process. More satisfactorily, the PAN J F still maintains 90% removal efficiency even after five cycles, which certifies it is an excellent scavenger and can be utilized to remove furfural in practice. [Display omitted] • A novel carbohydrazide functionalized polyacrylonitrile fiber (PAN J F) was designed. • PAN J F can remove the furfural from wastewater. • The maximum adsorption capacity of PAN J F for furfural can reach 140.4 mg g−1. • PAN J F still maintains 90% removal efficiency even after five cycles. [ABSTRACT FROM AUTHOR]