减压蒸馏塔分段抽真空新工艺实现工业化

介绍了金陵石油化工公司炼油厂常减压蒸馏装置采用一台减压炉、减压塔分段抽真空的新工艺及该工艺的工业化情况。该工艺在 2 .8Mt/a装置上历时 4年的生产运行中 ,实现了高真空、达到了增加总拔出率约 1.6%的预期目的 ,取得了年增效益千万元的良好效果。同时指出下段减压塔结构对深拔油质和量存在的影响。     

氧化物玻璃中短程有序的穆斯堡尔诺学研究

在以往对氧化物玻璃的穆斯堡尔研究中,通常将谱线按分立的洛仑兹线拟合。然而在玻璃中,由于电场梯度的分布,引起可观的谱线加宽 在本工作中我们用Hesse-Rubartshch法计算四极分裂的总分布,再将所得的分布曲线以高斯线型进行亚谱线拟合,分别给出四面体配位和八面体配位的贡献。所得到的平均四极裂距Δ和分布宽度σ_Δ分别对应于铁离子周围的环境对称性和位置相似性,从而用所得四极分裂分布可以量度玻璃中的短程有序。依据Brodbeck-Bukrey模型,再由四极分裂的分布导出铁离子周围环境的畸变参量的分布,由此得出关于玻璃中短程有序的更详细的定量数据。     

Cold crystallization of poly(ethylene naphthalene-2,6-dicarboxylate) by simultaneous measurements of X-ray scattering and dielectric spectroscopy

The isothermal cold crystallization of poly(ethylene naphthalene-2,6-dicarboxylate) was investigated by simultaneous small and wide angle X-ray scattering and dielectric spectroscopy (DS). By this experimental approach, simultaneously collected information was obtained about the specific changes occurring in both crystalline and amorphous phases during crystallization, namely about the chain ordering through wide angle X-ray scattering, about the lamellar crystals arrangement by means of small angle X-ray scattering, and about the amorphous phase evolution by means of DS. The results indicate that average mobility of the amorphous phase suffers a discontinuous decrease upon passing from the primary to the secondary crystallization regime. We interpret these results assuming that the restriction to the mobility of the amorphous phase occurs mainly in the amorphous regions between the lamellar stacks and not in the amorphous regions within the lamellar stacks.     

Resonance Assignments of Lowly Populated and Unstable Enzyme Intermediate Complex under Real-Time Conditions

Unstable and low-abundance protein complexes represent a large family of transient protein complexes that are difficult to characterize, even by means of high-resolution NMR spectroscopy. A method to assign the NMR signals of these unstable complexes through a combination of selective isotope labeling of amino acids in a protein and site-specific labeling the protein with a paramagnetic tag is presented herein. By using this method, the resonances of unstable thioester intermediate complex (lifetime <5 h and highest concentration ≈20 μm ) generated by Staphylococcus aureus sortase A and its peptide substrate under a real-time reaction have been assigned.     

Photoluminescence and thermal expansion of zirconium vanadate

The optical property and phase transition of ZrV₂O₇ were investigated by temperature-dependent X-ray diffraction, photoluminescence (PL), and Raman spectra. It was found that the material exhibited PL emission in the visible region. The temperature-dependent PL emission showed that the peak energy for emission (at red wavelength) presented a red shift from 10 to 80 K, and then a blue shift with the increase in temperature. The PL emission bands of ZrV₂O₇ shifted with change in temperature relating to its phase transition (80-100 K), which could be confirmed by temperature-dependent Raman spectra.     

Physico-chemical properties of V-Sb-oxide systems and their catalytic behaviour in oxidative dehydrogenation of light paraffins

Catalysts prepared as bulk VSb_0.1O_x and supported V₂O₅/Al₂O₃, V₂O₅-Sb₂O₃/Al₂O₃ and Sb₂O₃/Al₂O₃ (containing 0.5, 1 or 2 theoretical monolayers of V₂O₅ or Sb₂O₃) were tested in the oxidative dehydrogenation of iso-butane at 550°C in i-C₄H₁₀:O₂:He=20:10:70 gas mixture. Fresh and used catalysts were characterised by BET, XRD and XPS. Reactivity and thermochemistry of active oxygen taking part in the redox cycle with ethane and hydrogene were studied using in situ differential scanning calorimetry. Temperature-programmed desorption of O₂ in He flow was also investigated and in situ DRIFT was applied to investigate surface species of the catalysts in flows of i-C₄H₁₀, O₂ and i-C₄H₁₀/O₂ mixture. Supported VSb_yO_x catalysts are more active and selective than bulk one. V-only supported catalysts display a high efficiency due to the high reactivity of VOX-species. In bulk catalyst, the surface is enriched with antimony. In supported samples, the surfaces V/Sb are close to the calculated ones. In the presence of antimony, the amount of active oxygen species and their reactivity in redox transformation is improved. The rates of vanadium reduction and reoxidation are also higher. Compared to V-only catalysts, supported V-Sb-catalysts display a lower coking activity and higher on-stream stability.     

Heat-treatment of isomorphously substituted ZSM-5 (MFI) zeolites An ESR and Mössbauer spectroscopy and kinetic study

Fe-ZSM-5 zeolites comprise of three types (I, II and III) of iron (Fe³⁺) sites in both as synthesized (AS) and heat-treated states. Previous evidence could be confirmed by the assignment of ESR lines, registered in the X-band, stating: (i) type I framework Fe³⁺ sites (in T_h oxygen coordination), where charge compensation occurs mainly by Na⁺ ions and the crystal field (cf) approximates cubic symmetry, produce resonances at near to g = 2.00; (ii) type II and probably type III binuclear Fe...Fe dioxo- and oxo-bridges manifest themselves in producing slightly distorted surroundings of axial symmetry, and the relevant powder-averaged subspectrum is superimposed on the previous one in the g  2.45–1.98 interval. As the temperature of the heat-treatment (HT) is raised, type II and III sites will be annihilated with preference, under concomitant production of amorphous Fe₂O₃ possessing molecular dispersity. (iii) The weak ESR signal (2–4%) at g  4.27 is attributed to T_h coordinated framework sites in the surface layers (≈ 1 u.c. thick) under the influence of solid surface tension, giving rise to fully rhombic cf symmetry.

The size of the ejected Fe₂O₃ particles, as estimated from Mössbauer spectra (no hyperfine structure at 77 K) is less than 2.9 nm. The extremely large electron affinity of Fe³⁺ ions manifests itself in decreased ionicity (and unexpectedly dominant cubic symmetry), activity in biomimetic oxidations, autoreduction and spontaneous reoxidation etc.

In the liquid phase oxidation by hydrogen peroxide of n-hexane and cyclohexane the heat-treated Ti-ZSM-5 samples exhibited both activity- and selectivity dependence on HT. On the basis of experiences drawn from the heat-treatments proposal is made for the structures of the defect site (producing the 960 cm⁻¹ IR signal) and the active centre of selective oxidation. The proposal seems to be in accord with the experimental observations (isotopic exchange, MAS-NMR behaviour etc.) published so far.     

红外光谱法测定二元乙丙橡胶中乙烯、丙烯组成

阐述了测定乙丙橡胶中乙烯、丙烯组成的意义和方法,借助核磁共振数据建立了红外光谱法的标准工作曲线,并对其精确性进行了评价。     

Impedance characterization of Cr3+, Y3+ and Zr4+ activated forsterite nanoceramics synthesized by sol–gel method

The synthesis of forsterite-based ceramic nanopowders using sol–gel method assisted by further thermal treatment has been performed. X-ray diffraction and SEM analysis of the obtained nanopowders are presented. Detailed impedance spectroscopy study of the forsterite nanoceramics doped with Cr³⁺, Y³⁺ and Zr⁴⁺ ions has been carried out. Impedance spectra are interpreted in terms of equivalent circuits. Peculiarities of the electrical properties for each of the materials under study are discussed.     

Microstructural and high-temperature impedance spectroscopy study of Ba6MNb9O30 (M=Ga,Sc, In) relaxor dielectric ceramics with tetragonal tungsten bronze structure

This work reports on the microstructural and high-temperature impedance spectroscopy study of a family of dielectric ceramics Ba₆MNb₉O₃₀ (M=Ga, Sc, In) of tetragonal tungsten bronze (TTB) structure with relaxor properties. For Ba₆GaNb₉O₃₀ and Ba₆InNb₉O₃₀ pellets, the SEM images have revealed good, dense internal microstructures, with well-bonded grains and only discrete porosity; in contrast Ba₆ScNb₉O₃₀ pellets had a poorer microstructure, with many small and poorly-bonded grains gathered in agglomerates, resulting in significant continuous porosity and poorly defined grain boundary regions. The electroactive regions were characterised by the bulk and grain boundaries capacitances and resistances, while their contribution to the electrical conduction process was estimated by determining activation energies from the temperature (Arrhenius) dependence of both electric conductivities and time constants. For Ga and In analogues the electronic conductivity are dominated by the bulk response, while for Sc analogue, the poorly defined grain boundaries give a bulk-like response, mixing with the main bulk contribution.