RhCo双金属催化剂的研究 Ⅰ.RhCo双金属催化剂的金属-金属及金属-载体相互作用

利用XPS对以金属盐共浸渍制备的PH+CO/AL_2O_3和RH_2Co_2(CO)_12为前体制备的Rh_2Co_2/Al_2O_3催化剂的金属-金属及金属-载体相互作用进行了详细的研究.发现Rh+Co/Al_2O_3经400℃ H_2还原后RH的结合能与Rh~0的结合能接近,Co基本上以CoAL_2O_4状态存在,Co_0的谱峰很弱;而Rh_2Co_2/Al_2O_3经400℃H_2还原后Rh的结合能与Rh~0接近,Co除以CoAl_2O_4状态存在外,还有相当一部分以Co~0状态存在.上述结果揭示出两个样品的RH-Al_2O_3的相互作用弱,Co-Al_2O_3的相互作用强.Rh+Co/Al_2O_3上Rh-Co相互作用弱,而Rh_2Co_2/Al_2O_3在H_2还原后仍保持RhCo簇合物的强的Rh-Co相互作用,导致显著量的Co~0存在.     

高比表面碳化硅制备及其作为催化剂载体的应用

介绍了模板法、溶胶-凝胶法以及聚碳硅烷裂解法制备高比表面积碳化硅的主要过程和结果, 并介绍了碳化硅作为催化剂载体在多相催化中应用的研究进展. 对碳化硅在多相催化中的应用前景进行了展望.     

碳化硅为载体的氨合成催化剂的制备及性能研究

A sol-gel process catalyzed by oxalic acid was used for the preparation of SiC precursor from raw materials of tetraethyl orthosilicate (TEOS) and sucrose. The precursor thus obtained was homogeneous. Sintered with a certain heating program in an argon flow, the precursor was converted into the high surface area SiC. The high specific surface area silicon carbide was used as catalyst support for ammonia synthesis. The effect of the surface of the support, promoter and the amount of Ru on the catalytic activity for ammonia synthesis was studied. The results show that when the high specific surface area SiC of 113 m²·g^-1 is used as support, the prepared SiC-supported ruthenium catalyst has a relatively high activity(11.85%) under Ru 4wt%, Ba 4wt%, K 8wt%, 475 ℃, 10.0 MPa and 10 000 h^-1.     

载体效应对Ru催化剂F-T反应性能的影响

采用浸渍法将Ru负载于SiO₂、Al₂O₃和Beta分子筛制备了不同载体的Ru基F-T合成催化剂。通过N₂-物理吸附、XRD、NH₃-TPD、H₂-TPR、H₂-TPD、XPS和CO-DRIFTS等表征方法对不同催化剂的织构、物相、酸性、还原性质、吸附性能和电子状态信息进行了考察,并对不同载体催化剂的F-T反应性能及产物分布进行了研究。结果表明,不同载体Ru基催化剂在金属分散度、还原性质、对氢气吸附性能和电子状态等方面均存在较大差异。其中,酸性较弱的Ru/SiO₂催化剂具有较弱的金属载体相互作用、较小的颗粒粒径和较高的电子密度,同时该催化剂的Ru金属平台位点较多,导致其在F-T反应过程中表现较好的反应稳定性,其产物以重质烃为主,CH₄和轻质烃选择性较低。     

功能化石墨烯的制备及抗癌药物递送载体的研究

以聚苯乙烯磺酸钠(PSS)为保护剂,利用水合肼还原氧化石墨烯制备了一种新型的聚苯乙烯磺酸钠功能化石墨烯(PSS-GNS).结果表明制备的PSS-GNS是水溶分散性的纳米片层材料.考察了PSS-GNS对模型抗癌药物罗丹明6G(R6G)的吸附行为,结果表明PSS-GNS对R6G吸附量较大(2.77 mg/mg).体外释放研究结果表明PSS-GNS/R6G对R6G的释放具有p H响应性和缓释作用.PSS-GNS的细胞毒性较低,能顺利进入癌细胞内并持续缓慢地释放R6G.因此,PSS-GNS有望成为一种新型的抗癌药物递送载体.     

金属载体催化剂的涂层研究

在高温氧化处理不同时间的金属载体箔片上涂覆MgAl2O4/Al2O3过渡涂层,利用TG-DSC,XRD,SEM,BET和超声振动等分析测试技术,对载体和涂层的微观结构与表面特性进行研究.结果表明,在950 ℃下高温氧化5 h,箔片表面生成板状Al2O3晶须,有利于增强涂层与箔片的附着力.在载体表面涂覆一层MgAl2O4/Al2O3过渡涂层,有助于提高活性组分与金属载体的结合力,可以获得高结合强度的涂层结构,促使活性元素高度分散.     

新型聚合物载体茂金属催化剂

均相茂金属催化剂虽然有许多优点和特点,但也存在着某些不足之处,例如,不适于现在通用的气相和淤浆聚合工艺;要想达到足够的聚合活性需大量价格昂贵的MAO;相当多的均相茂金属催化剂不适于高温聚合（活性降低,分子极低）,不能很好地控制聚合物的形态,为了在工业上得到实际应用,必须将它们载体（非均相）化。通常采用的载体都是无机物,如SiO2、MgCl2、Al2O3等。由于无机载体表面具有酸性,负载茂金属催化剂活性有所降低,用聚合和作茂金属催化剂的载体很少有报道,我们研制了一种新型的聚合物载体茂金属催化剂,即可保持均相茂金属催化特点和优点,又能克服其缺点。其合成路线如下。     

金属基载体支撑的单原子催化剂用于光催化还原反应（英文）

金属原子均匀分散在无机金属基载体上构成一类独特的单原子催化剂(SACs),在光催化还原反应如析氢反应(HER)、二氧化碳还原反应(CRR)和氮还原反应(NRR)中有重要应用.关于SACs,有效的金属-载体相互作用(M-SI)是在载体上锚定金属单原子(SA)位点的关键.SAs主要通过4种方式与载体相互作用:(1)与载体表面“配位不饱和位点”处的原子键合;(2)取代表面原子;(3)与表面有机/无机官能团桥联或者配位;(4)利用载体表面空间限域效应锚定在载体上.不同的M-SI可获得不同的SAs负载量、配位结构和可调谐性.本文讨论了金属单原子有效锚定在金属基载体上所需构建的几种典型的M-SI方式.通过阐述特定SACs在三种光还原反应中的应用实例,讨论了SA和M-SI对催化性能(反应活性、选择性和稳定性)的影响.不同的M-SI可将贵金属(如Pt, Pd, Rh和Ru)和非贵金属(如V, Cr, Fe, Mn, Co, Ni, Cu, Mo等)原子固定在半导体载体上,通过调节配位环境来调控SA的价态、电荷转移、电子寿命和载体能带结构.SA可以充当质子(H⁺)吸附和还原位点,可...     

机动车尾气净化催化剂金属载体涂层的研究

采用Fe-Cr-Al-Y金属载体为研究对象,用氧化-磷化和溶胶-凝胶技术在金属载体表面形成活性γ-Al2O3涂层,实验确定了合适的磷化温度和磷化时间、溶胶中γ-Al2O3浓度和升温机制,结果证明预先在载体表面涂覆一层氧化-磷化膜,有助于提高活性组分与金属载体的结合力,可以获得高结合强度且活性组分均匀分布的涂层.     

Phosphorus‐Doped Graphene Oxide Layer as a Highly Efficient Flame Retardant

A simple and easy process has been developed to efficiently dope phosphorus into a graphene oxide surface. Phosphorus‐doped graphene oxide (PGO) is prepared by the treatment of polyphosphoric acid with phosphoric acid followed by addition of a graphene oxide solution while maintaining a pH of around 5 by addition of NaOH solution. The resulting materials are characterized by X‐ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD), Raman spectroscopy, thermogravimetric analysis (TGA), and scanning electron microscopy (SEM). The as‐made PGO solution‐coated cloth exhibits excellent flame retardation properties. The PGO‐coated cloth emits some smoke at the beginning without catching fire for more than 120 s and maintains its initial shape with little shrinkage. In contrast, the pristine cloth catches fire within 5 s and is completely burned within 25 s, leaving trace amounts of black residue. The simple technique of direct introduction of phosphorus into the graphene oxide surface to produce phosphorus‐doped oxidized carbon nanoplatelets may be a general approach towards the low‐cost mass production of PGO for many practical applications, including flame retardation.     

Excellent Capacitive Performance of a Three‐Dimensional Hierarchical Porous Graphene/Carbon Composite with a Superhigh Surface Area

Three‐dimensional hierarchical porous graphene/carbon composite was successfully synthesized from a solution of graphene oxide and a phenolic resin by using a facile and efficient method. The morphology, structure, and surface property of the composite were investigated intensively by a variety of means such as scanning electron microscopy (SEM), transmission electron microscopy (TEM), N₂ adsorption, Raman spectroscopy, and Fourier transform infrared spectroscopy (FTIR). It is found that graphene serves as a scaffold to form a hierarchical pore texture in the composite, resulting in its superhigh surface area of 2034 m²g^?1, thin macropore wall, and high conductivity (152 S m^?1). As evidenced by electrochemical measurements in both EMImBF₄ ionic liquid and KOH electrolyte, the composite exhibits ideal capacitive behavior, high capacitance, and excellent rate performance due to its unique structure. In EMImBF₄, the composite has a high energy density of up to 50.1 Wh kg^?1 and also possesses quite stable cycling stability at 100 °C, suggesting its promising application in high‐temperature supercapacitors. In KOH electrolyte, the specific capacitance of this composite can reach up to an unprecedented value of 186.5 F g^?1, even at a very high current density of 50 A g^?1, suggesting its prosperous application in high‐power applications.     

Electrochemical Pretreatment of Amino‐Carbon Nanotubes on Graphene Support as a Novel Platform for Bilirubin Oxidase with Improved Bioelectrocatalytic Activity towards Oxygen Reduction

The electrochemical conditioning of amino‐carbon nanotubes (CNTs) on a graphene support in an alkaline solution is used to produce ?NHOH as hydrophilic functional groups for the efficient immobilization of bilirubin oxidase enzyme. The application of the immobilized enzyme for the direct electrocatalytic reduction of O₂ is investigated. The onset potential of 0.81 V versus NHE and peak current density of 2.3 mA cm^?2 for rotating modified electrode at 1250 rpm, indicate improved biocatalytic activity of the proposed system for O₂ reduction.