Ni/SAPO-11催化剂上棕榈油加氢脱氧制异构烃燃料(英)

采用水热法合成了小粒径、具有介孔结构的SAPO-11分子筛.采用浸渍法制备了不同Ni负载量的Ni/SAPO-11催化剂.并采用X射线衍射,扫描电镜,N₂物理吸附-脱附,NH₃程序升温脱附,热重和H₂化学吸附技术对该类催化剂的物理化学性质进行了详细表征.结果表明,SAPO-11较大表面积和介孔结构可分散Ni,使得Ni粒子尺寸较小.在棕榈油加氢脱氧制备液体烃类燃料反应中,液体烷烃产物由相关脂肪酸中间产物的直接加氢脱氧和脱羰-加氢脱氧两种途径产生.Ni/SAPO-11催化剂的弱/中强酸性质及其匹配的金属-酸双功能可显著抑制积炭反应,提高催化剂的寿命,液体烷烃收率高达70%,异构烷烃选择性超过80%.     

Electro-Mechanochemical Atom Transfer Radical Cyclizations using Piezoelectric BaTiO3

The formation and regeneration of active Cu^I species is a fundamental mechanistic step in copper-catalyzed atom transfer radical cyclizations (ATRC). Typically, the presence of the catalytically active Cu^I species in the reaction mixture is secured by using high Cu^I catalyst loadings or the addition of complementary reducing agents. In this study it is demonstrated how the piezoelectric properties of barium titanate (BaTiO₃) can be harnessed by mechanical ball milling to induce electrical polarization in the strained piezomaterial. This strategy enables the conversion of mechanical energy into electrical energy, leading to the reduction of a Cu^II precatalyst into the active Cu^I species in copper-catalyzed mechanochemical solvent-free ATRC reactions.     

Anisotropic Poisson Effect and Deformation-Induced Fluorescence Change of Elastic 9,10-Dibromoanthracene Single Crystals

Elastic organic crystals have attracted considerable attention as next-generation flexible smart materials. However, the detailed information on both molecular packing change and macroscopic mechanical crystal deformations upon applied stress is still insufficient. Herein, we report that fluorescent single crystals of 9,10-dibromoanthracene are elastically bendable and stretchable, which allows a detailed investigation of the deformation behavior. We clearly observed a Poisson effect for the crystal, where the short axes (b and c-axes) of the crystal are contracted upon elongation along the long axis (a-axis). Moreover, we found that the Poisson's ratios along the b-axis and c-axis are largely different. Theoretical molecular simulation suggests that the tilting motion of the anthracene may be responsible for the large deformation along the c-axis. Spatially resolved photoluminescence (PL) measurement of the bent elastic crystals reveals that the PL spectra at the outer (elongated), central (neutral), and inner (contracted) sides are different from each other.     

Ordered Large-Pore MesoMOFs Based on Synergistic Effects of TriBlock Polymer and Hofmeister Ion

Ordered mesoporous metal–organic frameworks (mesoMOFs) were constructed with a uniform pore size up to about 10 nm and thick microporous walls, opening up the possibility for the mass diffusion of large-size molecules through crystalline MOFs. The synergistic effects based on triblock copolymer templates and the Hofmeister salting-in anions promote the nucleation of stable MOFs in aqueous phase and the in situ crystallization of MOFs around templates, rendering the generation of a microcrystal with periodically arranged large mesopores. The improved mass transfer benefiting from large-pore channels, together with robust microporous crystalline structure, endows them as an ideal nanoreactor for the highly efficient digestion of various biogenic proteins. This strategy could set a guideline for the rational design of new ordered large-pore mesoMOFs with a variety of compositions and functionalities and pave a way for their potential applications with biomacromolecules.     

Helicity Control of Polymeric Backbones with Alternating cis-trans Double Bonds in Cyclopolymerized Dipropargyl Amides

We report the synthesis of new helical polymeric structures having alternating cis and trans double bonds and chiral amino acid side chains by metathesis cyclopolymerization. The polymer helicity, which is generated by the interaction between fluorenylmethyloxycarbonyl (Fmoc) groups in the side chains, is dramatically affected by solvents. A thorough experimental and theoretical analysis including nuclear magnetic resonance, atomic force microscopy, and density functional theory and molecular mechanics calculations suggests that the helicity of both backbone and side chains are determined by anti-syn rotation of the carbamate groups and by the different interactions of the Fmoc groups with solvents.     

Heterogeneous freezing on pyroelectric poly(vinylidene fluoride-co-trifluoroethylene) thin films

Active deicing of technical surfaces, such as for wind turbines and heat exchangers, currently requires the usage of heat or chemicals. Passive coating strategies that postpone the freezing of covering water would be beneficial in order to save costs and energy. One hypothesis is that pyroelectric active materials can achieve this because of the surface charges generated on these materials when they are subject to a temperature change. High-quality poly(vinylidene fluoride-co-trifluoroethylene) (P(VDF-TrFE)) thin films with a high crystallinity, prefererd edge-on orientation, low surface roughness, and comprised of the β-analogous ferroelectric phase were deposited by spin-coating. Freezing experiments with a cooling rate of 1 K min⁻¹ were made on P(VDF-TrFE) coatings in order to separate the effect of different parameters such as the poling direction, film thickness, used solvent, deposition process, underlying substrate, and annealing temperature on the achievable supercooling. The topography and the underlying substrate significantly changed the distribution of freezing temperatures of water droplets in contact with these thin films. In contrast, no significant effect of the thickness, morphology, or pyroelectric effect of the as-prepared domain-state on the freezing temperatures was found.     

磷脂膜的相行为对氧化石墨烯与磷脂膜相互作用的影响

通过使用不同相变温度的磷脂分子并调节二者的比例构筑了不同相态的磷脂膜, 并利用表面增强红外光谱和激光共聚焦显微镜研究了磷脂膜的相行为对氧化石墨烯和磷脂膜相互作用的影响. 结果表明, 氧化石墨烯对磷脂膜中磷脂分子的抽提作用具有显著的相态选择性, 其选择性地抽提流动相的磷脂分子; 氧化石墨烯对流动相磷脂的抽提作用受到膜中凝胶相磷脂存在比例的影响, 只有在流动相磷脂分子占磷脂膜中磷脂分子的绝大部分时才能够发生抽提作用, 且只有流动相的磷脂分子被抽提.     

Hammett and Brown correlations in the structure and electronic properties of H2Si=SiHAr (Ar = p-C6H4X; X = NH2, OH,Me, H,F, Cl,CHO, COOH,CN, NO2) molecules

Substituent effect on the structure and electronic properties of H₂Si=SiHAr (Ar = p-C₆H₄X; X = NH₂, OH, Me, H, F, Cl, CHO, COOH, CN, NO₂) molecules are studied at the CAM-B3LYP/6-311G(d,p) level of theory. Energy decomposition analysis (EDA) is used as a useful tool for illustrating the interaction between H₂Si and SiHAr fragments in HArSi=SiH₂ molecules. Energetic analysis reveals that the singlet state of the fragments is more stable than triplet state. Also, interactions are stronger in the presence of electron-withdrawing groups (EWGs) in comparison to electron donating groups (EDGs). EDG and EDG effects are investigated on the stability of fragments, frontier orbital energy, distortion, HOMO–LUMO gap, electron-donating (ω⁻) and electron-accepting (ω⁺) powers of the studied molecules. Then, the correlations between these calculated parameters with the Hammett and Brown constants (σ_p and σ_p⁺, respectively) are provided. Also, time-dependent density functional theory method (TD-DFT) is employed for the determination of the strongest absorption band values (λ_max,el) of these molecules. This absorption band is attributed to the HOMO →LUMO transition.     

多酸结构对纳米钛硅TS-1沸石催化氧化脱硫性能的影响

采用浸渍法合成了纳米钛硅TS-1沸石负载的钼系列多金属氧酸盐(POM)复合催化剂,采用扫描电子显微镜(SEM)、傅里叶红外光谱(FT-IR)、固体紫外漫反射(UV-Vis)、X-ray粉末衍射(XRD)、氮气吸附脱附(BET)、³¹P和²⁹Si魔角核磁共振(MAS-NMR)等对催化剂的结构进行表征。 研究结果表明,在低温焙烧或烘干条件下,负载后催化剂多酸的结构保持,钼酸铵高温(550 ℃)焙烧后转变为三氧化钼。 以有机硫化物噻吩(TH)、苯并噻吩(BT)和二苯并噻吩(DBT)的正辛烷溶液为模拟油品评价了催化剂的氧化脱硫性能。 实验结果表明,纳米TS-1沸石载体上不同结构多酸作为脱硫催化剂对硫化物的脱除活性顺序为:Keggin型Mo-POM＞Anderson型Mo-POM＞Dawson型Mo-POM＞Mo-金属氧化物。以上述负载的多酸为催化剂,在反应条件为:V(模拟油)=V(乙醇)=10.0 mL,m(催化剂)=0.2 g,n(H₂O₂)∶n(S)=10∶1,温度60 ℃,硫化物按照由易到难的脱除顺序为TH＞DBT＞BT,与常规的TS-1沸石或者多酸催化剂的脱除顺序存在明显差异。 这是纳米TS-1沸石对于有机硫分子氧化反应的择形效应和POM催化氧化脱硫的电子云密度影响综合作用的结果。 Keggin型Mo-POM催化剂具有良好的循环使用性能,是一类制备方法简单、催化活性高且稳定性好的绿色环保型催化剂。