Synthesis of zeolites from coal fly ash: application of a statistical experimental design

With the intention of decreasing the experimental test runs during the optimization of synthesis of zeolites from fly ash, a 2⁴ full-factorial experimental design was applied in this study. The preparation parameters that had showed significant influence on the synthesis of pure phase zeolite Na-P1 using one-step-at-a-time experimental approach were included, but extended also to those parameters of importance identified in the literature. At the same time, it was important that the levels of variation of parameters not be restricted to the conditions where a pure phase of zeolite Na-P1 was formed. The four synthesis variables investigated were; NaOH concentration (NaOH:SiO₂ molar ratio ranged between 0.35 and 0.71), ageing temperature (35?C55°C), hydrothermal treatment time (36?C60?h) and temperature (130?C150°C). The results obtained were assessed by the improvement in the cation exchange capacity (CEC) of the obtained zeolite, which showed that the phase purity is strictly controlled by the synthesis conditions. In the end, this approach provided sufficient understanding of the relationship between product properties and the four synthesis parameters, which took into account the individual effects as well as linear and nonlinear interacting phenomena. From the analysis, it was found that the main effects were ageing temperature and hydrothermal treatment time and temperature, which showed some interactions among each other.     

Layer-by-layer growth of thin amorphous solid water films on Pt(111) and Pd(111)

The growth of amorphous solid water (ASW) films on Pt(111) is investigated using rare gas (e.g., Kr) physisorption. Temperature programmed desorption of Kr is sensitive to the structure of thin water films and can be used to assess the growth modes of these films. At all temperatures that are experimentally accessible (20-155 K), the first layer of water wets Pt(111). Over a wide temperature range (20-120 K), ASW films wet the substrate and grow approximately layer by layer for at least the first three layers. In contrast to the ASW films, crystalline ice films do not wet the water monolayer on Pt(111). Virtually identical results were obtained for ASW films on epitaxial Pd(111) films grown on Pt(111). The desorption rates of thin ASW and crystalline ice films suggest that the relative free energies of the films are responsible for the different growth modes. However, at low temperatures, surface relaxation or "transient mobility" is primarily responsible for the relative smoothness of the films. A simple model of the surface relaxation semiquantitatively accounts for the observations.     

Polynomials in operator space theory: matrix ordering and algebraic aspects

We extend the \(\lambda \)-theory of operator spaces given in Defant and Wiesner (J. Funct. Anal. 266(9): 5493–5525, 2014), that generalizes the notion of the projective, Haagerup and Schur tensor norm for operator spaces to matrix ordered spaces and Banach \(*\)-algebras. Given matrix regular operator spaces and operator systems, we introduce cones related to \(\lambda \) for the algebraic operator space tensor product that respect the matricial structure of matrix regular operator spaces and operator systems, respectively. The ideal structure of \(\lambda \)-tensor product of \(C^*\)-algebras has also been discussed.     

具有中孔结构的SO2-4/Zr-HMS型固体超强酸的合成和结构表征

用TEOS-Zr-HAD-H2O-Ethanol体系合成了Zr-HMS的中孔分子筛, 脱除模板剂后用0.5 mol/L硫酸处理和550 ℃高温焙烧3 h, 制得一种中孔SO2-4/Zr-HMS超强酸催化剂. 采用XRD对其结构进行表征. 用指示剂法、 TG和NH3-TPD对其酸性进行了表征. 结果表明, 经过一系列处理后制得的SO2-4/Zr-HMS催化剂具备HMS中孔分子筛的结构特征, 其酸强度可达H0=-13.75. 在锆及SO2-4含量远远低于SO2-4/ZrO2的条件下, SO2-4/Zr-HMS催化剂对于苯酐和正丁醇酯化反应的活性仍高于SO2-4/ZrO2催化剂.     

Low-energy electron-stimulated luminescence of thin H2O and D2O layers on Pt(111)

The electron-stimulated luminescence (ESL) from amorphous solid water and crystalline ice films deposited on Pt(111) at 100 K is investigated as a function of the film thickness, incident electron energy (5-1000 eV), isotopic composition, and film structure. The ESL emission spectrum has a characteristic double-peaked shape that has been attributed to a transition between a superexcited state (C) and the dissociative, first excited state (A) in water: C --> A. Comparing the electron-stimulated luminescence and O2 electron-stimulated desorption (ESD) yields versus incident electron energy, we find the ESL threshold is approximately 3 eV higher than the O2 ESD threshold, which is close to the center of the emission spectrum near 400 nm and supports the C --> A assignment for the ESL. For thin films, radiative and nonradiative interactions with the substrate tend to quench the luminescence. The luminescence yield increases with coverage since the interactions with the substrate become less important. The ESL yield from D2O is approximately 4-5 times higher than that from H2O. With use of layered films of H2O and D2O, this sizable isotopic effect on the ESL is exploited to spatially profile the luminescence emission within the ASW films. These experiments show that most of the luminescence is emitted from within the penetration depth of the incident electron. However, the results depend on the order of the isotopes in the film and can be modeled by assuming some migration of the electronically excited states within the film. The ESL is very sensitive to defects and structural changes in solid water, and the emission yield is significantly higher from amorphous films than from crystalline ice.     

Electron-stimulated reactions at the interfaces of amorphous solid water films driven by long-range energy transfer from the bulk

The electron-stimulated production of D2 from amorphous solid D2O deposited on Pt(111) is investigated as a function of film thickness. The D2 yield has two components that have distinct reaction kinetics. Using isotopically layered films of H2O and D2O demonstrates that the D2 is produced in reactions that occur at both the Pt/amorphous solid water (ASW) interface and the ASW/vacuum interface, but not in the bulk. The energy for the reactions, however, is absorbed in the bulk of the films and electronic excitations diffuse to the interfaces where they drive the reactions.