A versatile hydrogel template for metal nano particle preparation and their use in catalysis

We report the synthesis of a novel bulk hydrogel based on acrylamidoglycolic acid (AAGA) and its use as a template in the preparation of different metal nanoparticles. Furthermore, we demonstrate the efficient utilization of p(AAGA) composite hydrogel as a reactor vessel in the reduction of an organic contaminant, 4-nitrophenol (4-NP) to 4-aminophenol (4-AP). The swelling characteristics of the hydrogel at different pH and different concentrations of salts (NaNO_3, NaCI) were studied, and experimental molecular mass between crosslink (M_c) values was calculated. Experimental parameters that affect the 4-NP reduction rate such as temperature, amount of catalysis, co-catalysis, concentrations of 4-NP and of NaBH₄ were investigated. The kinetics of the reduction reaction under different reaction conditions was also evaluated to determine the activation parameters. Activation energy for the reduction of 4-NP was 33.783 kJ mol⁻¹ and p(AAGA)-Ag composites possessed 88% activity at the end of five repetitive uses.     

加成型硅橡胶铂催化剂的制备及其活性研究

合成了几种不同的铂催化剂 (氯铂酸二乙烯基四甲基二硅氧烷 ,氯铂酸 -异丙醇 ,氯铂酸 -邻苯二甲酸二乙酯 )。考察了其对于有机硅橡胶加成聚合反应的催化活性 ,并从催化机理的角度初步探讨了催化剂不同活性差异的原因     

木质素碳纳米材料制备及在催化中的应用研究进展

木质素是自然界储量丰富的可再生资源,含碳量高且具有三维网状结构和大量共轭结构。碳材料是一类具有极大应用价值的催化材料,特别是在电催化、热催化和光催化领域。以木质素为原料制备高活性的木质素碳基催化剂是实现木质素高附加值利用有效的途径之一。木质素碳催化材料研究涉及化学、化工和物理等多个学科领域,制备性能优异和稳定性良好的木质素碳基催化剂仍充满挑战。本文主要总结了木质素碳材料的制备研究进展,以及介绍了木质素碳材料在光催化、热催化和电催化等领域的应用研究现状。此外,还分析了当前木质素碳基催化材料存在的问题,并展望了未来的发展趋势和重点研究方向。     

NaOH modified P(acrylamide) hydrogel matrices for in situ metal nanoparticles preparation and their use in H2 generation from hydrolysis of NaBH4

Crosslinked poly(acrylamide) (p(AAm)) as neutral hydrogel is synthesized via photo polymerization technique, and the amide groups within p(AAm) matrices are converted to strongly ionizable carboxylic acids groups via facile modification route by simple treatment of NaOH to obtained NaOH‐p(AAm) hydrogels. Because of the highly ionizable nature of carboxylate groups within mod‐p(AAm), the swelling and metal ion absorbing capacities are increased tremendously, almost 40 and 7.5 folds, respectively. The Co(II) and Ni(II) metal ions are loaded into NaOH‐p(AAm) hydrogels, and are treated with NaBH₄ to form corresponding metal nanoparticles in situ within mod‐p(AAm) matrices, and used in H₂ generation production from hydrolysis of NaBH₄. Various parameters such as functionality of polymeric matrices, the kinds and the amount of metal nanoparticles, and the temperature effecting the H₂ generation are investigated. Comparable low E_a with the similar researches in the literature, E_a = 20.07 ± 0.05 kJ mol^?1 is obtained in NaBH₄ hydrolysis catalyzed by NaOH‐p(AAM)‐Co composite system. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41106.     

浆态床合成二甲醚用CuZnAlSi催化剂的完全液相法制备及表征

采用完全液相法制备了不同SiO₂含量的二甲醚(DME)合成CuZnAlSi双功能催化剂,并在浆态床反应器中评价其催化反应活性,通过in-situ XPS、XRD、BET、NH₃-TPD等方法对其物理化学性能进行研究。结果表明,CuZnAl催化剂中加入SiO₂组分,能够促进活性组分Cu的分散,并通过与AlOOH的作用调变催化剂的孔结构和表面酸性,从而提高催化剂在DME合成反应中的活性。准原位 XPS表征结果显示,还原后的催化剂表面Cu⁰和ZnO共同构成DME合成反应中的甲醇合成活性中心。SiO₂的加入可能导致Cu、Zn和Al组分间的相互作用减弱,催化剂稳定性降低。     

Versatile p(3-sulfopropyl methacrylate) hydrogel reactor for the preparation of Co,Ni nanoparticles and their use in hydrogen production

In this study, polymeric hydrogels derived from 3-sulfopropyl methacrylate (SPM) were used in the preparation of composite-catalyst system in hydrogen generation from hydrolysis of NaBH₄. In order to generate pores and determine their effect on hydrogen production, silica based p(SPM) hydrogels were synthesized also prepared. Additionally, the effects of metal type, temperature, the amount of the catalyst, metal reloading, and reusability were investigated. The activation energy, activation enthalpy, and activation entropy for the hydroylsis reaction of NaBH₄ solution in the presence of p(SPM)–Co catalyst system were calculated as 41.67 kJ mol^?1, 38.15 kJ mol^?1, ?173.139 J/mol K, respectively.     

High-throughput experimentation techniques for the preparation and testing of supported precious metal catalysts in liquid-phase hydrogenation

Miniaturisation and parallelisation are fundamental strategies to enable the productivity improvements achievable by high-throughput experimentation (HTE). This paper reports how the approach has been used to allow robotic preparation of supported precious metal catalysts and parallel techniques for subsequent reaction testing. It will be shown how HTE can shorten catalyst development times through increased productivity, as well as enabling a greater diversity space to be explored than would otherwise occur. This revised version was published online in June 2006 with corrections to the Cover Date.     

Lignocellulosic biomass for the preparation of cellulose‐based hydrogel and its use for optimizing water resources in agriculture

Recently, efforts have been devoted to find ways in utilizing biomass as feedstocks for the production of organic chemicals. This is because of its abundance, renewability and worldwide distribution. Lignocellulosic agricultural waste materials are regarded as abundant, inexpensive, and readily available natural resources for both chemical and paper industries. Hydrogels are polymeric materials that vary in their origin and composition and can absorb large amount of water without dissolving. In our study, cellulose‐based acrylic acid hydrogel was synthesized starting from rice straw as a source for the lignocellulosic material, where cellulose was first isolated after alkaline‐acid pulping treatment followed by bleaching step with sodium hypochlorite resulting of 90.8% holocellulose. The cellulose‐based acrylic acid hydrogel was synthesized applying heterogeneous reaction and shows a swelling ratio more than 3000%. The resulting hydrogel was further characterized with FT‐IR and SEM. On the other hand, comparison between the rice straw‐based hydrogel and the commercially available acrylamide hydrogel was studied for improving maize production in salt affected soil as well as in the growth promoters of maize under water stress. The experimental results demonstrated that the yield parameters were increased with increasing irrigation rates. Both types of hydrogels introduce positive and significant effect compared to the one without adding hydrogels. Also, acrylamide hydrogel was effective for improving almost yield parameters more than applying rice straw‐based hydrogel. Generally, the addition of hydrogel increases the nutrient concentration, uptake, and both of water and nutrients use efficiency. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42652.     

An improved phase‐inversion process for the preparation of silica/poly[styrene‐co‐(acrylic acid)] core–shell microspheres: synthesis and application in the field of polyolefin catalysis

Spherical and well‐dispersed silica/poly[styrene‐co‐(acrylic acid)] (SiO₂/PSA) core–shell particles have been synthesized using an improved phase‐inversion process. The resulting particles were successfully used as supports for polyolefin catalysts in the production of polyethylene with broad molecular weight distribution. Through the vapor phase, instead of the liquid phase in the traditional process, a non‐solvent was introduced into a mixture of micrometer‐sized SiO₂ and PSA solution. The core–shell structure of the resulting SiO₂/PSA microspheres was confirmed using optical microscopy, scanning electron microscopy, Fourier transfer infrared spectrometry, thermogravimetric analysis and measurement of nitrogen adsorption/desorption isotherms. In order to avoid agglomeration of particles and to obtain a good dispersion of the SiO₂/PSA core–shell microspheres, the non‐solvent was added slowly. As the concentration of PSA solution increased, the surface morphology of the core–shell particles became looser and more irregular. However, the surface area and the pore volume remained the same under varying PSA concentrations. The SiO₂/PSA core‐shell microspheres obtained were used as a catalyst carrier system in which the core supported (n‐BuCp)₂ZrCl₂ and the shell supported TiCl₄. Ethylene/1‐hexene copolymerization results indicated that the zirconocene and titanium‐based Ziegler–Natta catalysts were compatible in the hybrid catalyst, showing high activities. The resulting polyethylene had high molecular weight and broad molecular weight distribution. Copyright © 2010 Society of Chemical Industry