CuCo/BNNSs纳米催化剂对固态储氢材料氨硼烷水解的催化性能

采用共还原法将CuCo双金属负载到通过聚乙烯吡咯烷酮(PVP)辅助离子插层法制备的少层氮化硼纳米片(BNNSs)上,获得了平均粒径为2.7 nm且高度分散的铜钴/氮化硼纳米片(CuCo/BNNSs)纳米催化剂。通过原子力显微镜(AFM)、X射线衍射(XRD)、傅里叶转换红外光谱(FTIR)、拉曼光谱(Raman)、X射线光电子能谱(XPS)、扫描电子显微镜(SEM)和高分辨率透射电镜(HRTEM)对载体及催化剂的结构及形貌进行表征,并研究了CuCo/BNNSs的催化性能。研究发现,由于Cu、Co、BNNSs和OH-之间高效的四重效应协同使得Cu0.5Co0.5/BNNSs纳米催化剂在室温、pH=14条件下对氨硼烷(AB,NH3BH3)水解释氢具有极高的催化活性。转化频率(TOF)值达到104.52 molH2·molmetal^-1·min^-1,且CuCo/BNNSs纳米催化剂具有良好的稳定性,6次循环利用后仍保持较高催化活性。     

“硼”然心动——硼单质及其化合物*

硼是一种特殊的“准金属元素”,其独特的成键规律和化学性质使得硼及其化合物成为一类特殊的功能材料。介绍了硼单质的发现史,重点围绕硼单质、硼烷及其在国防等领域的应用展开。     

Synthesis of a Novel Co-B/CTAB Catalyst via Solid-state-reaction at Room Temperature for Hydrolysis of Ammonia-borane

Cobalt-boride(Co-B) is emerging as one of the promising materials in the base-hydrolytic dehydrogenation of ammonia-borane(AB). In order to avoid the low specific area and poor catalytic capacity of Co-B catalyst caused by aggregation arising from the strong reducing property and rapid reaction condensation of sodium borohydride(NaBH₄), novel cobalt boride/cetyltrimethylammonium bromide(Co-B/CTAB) catalyst was obtained via solid-state grinding at room temperature, and the catalyst was further characterized by XRD, SEM, XPS and BET. The hydrogen generation rate(HGR) was then determined by the hydrolysis reaction of AB. The SEM images indicate that a lot of irregular folds and curled edges are formed on the sample with a maximum surface area of 145.57 m²/g, thus possibly resulting in the high hydrogen production(HGR was 10.68 L·min^-1·g^-1), which may be attributed to CTAB that provide favorable large specific surface area and abundant porous structure. Additionally, catalyst will not be affected by solvants during solid-state reaction. As a diluent, the surfactant CTAB hindered the reaction rate of sodium borohydride reduction to cobalt boride and obtained the novel catalyst with a large specific surface area.     

氨硼烷催化水解制氢

氢气作为全球公认的清洁能源载体,备受关注。寻找安全高效的储氢材料以转型到氢能社会是当前氢能应用面临最大的挑战之一。氨硼烷(NH₃BH₃,AB)具有非常高的储氢质量分数(19.6 wt%)和体积储氢密度(0.145 kgH₂/L),因其在储氢和放氢性能方面的显著优势,被认为是一种颇具应用潜力的化学储氢材料。氨硼烷能够通过热解、醇解和水解放出氢气。其中,氨硼烷水解制氢可以通过催化剂进行可控放氢,且具有反应条件温和、不产生CO(易使催化剂中毒)等优点,被认为是一种安全高效和实用性强的制氢技术。本文简要介绍了氨硼烷的性质和合成,阐述了氨硼烷水解制氢的机理,综述了近年来氨硼烷水解制氢催化剂的研究进展,分析了碱对氨硼烷水解制氢的促进作用,并讨论了水解产物回收利用问题。     

Zirconium-Catalyzed Atom-Economical Synthesis of 1,1-Diborylalkanes from Terminal and Internal Alkenes

A general and atom-economical synthesis of 1,1-diborylalkanes from alkenes and a borane without the need for an additional H₂ acceptor is reported for the first time. The key to our success is the use of an earth-abundant zirconium-based catalyst, which allows a balance of self-contradictory reactivities (dehydrogenative boration and hydroboration) to be achieved. Our method avoids using an excess amount of another alkene as an H₂ acceptor, which was required in other reported systems. Furthermore, substrates such as simple long-chain aliphatic alkenes that did not react before also underwent 1,1-diboration in our system. Significantly, the unprecedented 1,1-diboration of internal alkenes enabled the preparation of 1,1-diborylalkanes.     

19F NMR Investigations of the Reaction of B(C6F5)3 with Different Tri(alkyl)aluminum Compounds

Tris(pentafluorophenyl)borane, B(C₆F₅)₃ reacts with triethylaluminum, AlEt₃ to a mixture of Al(C₆F₅)_3−nEt_n and Al₂(C₆F₅)_6−nEt_n compounds depending on the B/Al ratio. From excess borane to excess AlEt₃ the species Al(C₆F₅)₃ → Al(C₆F₅)₂Et Al₂(C₆F₅)₄Et₂ → Al₂(C₆F₅)₃Et₃ → Al₂(C₆F₅)₂Et₄ → Al₂(C₆F₅)Et₅ are formed and differentiated by their para-F signal in ¹⁹F NMR. The reaction between B(C₆F₅)₃ and the higher aluminum alkyls, tri(iso-butyl)aluminum and tri(n-hexyl)aluminum AlR₃ (R = i-Bu, n-C₆H₁₃) is slower and requires AlR₃ excess to shift the C₆F₅ R exchange equilibria to almost complete formation of Al(C₆F₅)R₂ and BR₃. At equimolar ratio the equilibrium lies on the side of the unchanged borane together with its boranate [B(C₆F₅)₃R]⁻ anion. For tri(n-octyl)aluminum even at large Al(n-C₈H₁₇)₃ excess no C₆F₅ alkyl exchange can be observed, but boranate anions form.     

Synthesis of 3-Aryl-4(3H)-quinazolinones from Anthranilic Acids and Triethyl Orthoformate

A one-step, convenient approach to the synthesis of 3-aryl-4(3H)-quinazolinones by the reaction of anthranilic acid with triethyl orthoformate in the presence of a catalytic amount of concentrated sulfuric acid has been developed. The possible reaction pathway was proposed.     

“Activated Borane” – A Porous Borane Cluster Network as an Effective Adsorbent for Removing Organic Pollutants

The unprecedented co-thermolysis of decaborane(14) (nido-B₁₀H₁₄) and toluene results in a novel porous material (that we have named “activated borane”) containing micropores between 1.0 and 1.5 nm in diameter and a specific surface area of 774 m² g⁻¹ (Ar, 87 K) that is thermally stable up to 1000 °C. Solid state ¹H, ¹¹B and ¹³C MAS NMR, UV-vis and IR spectroscopies suggest an amorphous structure of borane clusters interconnected by toluene moieties in a ratio of about three toluene molecules for every borane cluster. In addition, the structure contains Lewis-acidic tri-coordinated boron sites giving it some unique properties. Activated borane displays high sorption capacity for pollutants such as sulfamethoxazole, tramadol, diclofenac and bisphenol A that exceed the capacity of commercially-available activated carbon. The consistency in properties for each batch made, and the ease of its synthesis, make activated borane a promising porous material worthy of broad attention.     

Reaction of Triethyl Phosphite with Boron Tribromide

Summary.  Reaction of boron tribromide with triethyl phosphite led to the formation of triethyl tribromoborophosphate 1, a complex bearing a P→B bond. Received November 19, 1999. Accepted (revised) January 21, 2000