分子筛催化剂表征的研究

本文采用原子吸收光谱、X射线衍射、扫描电镜、元素分析等方法分别对分子筛催化剂在催化裂化反应前后进行了表征。探讨了催化剂失活的原因，以及活化后与新鲜、失活催化剂的差别。     

Regeneration and renovation in queues

Regenerative events for different queueing models are considered. The aim of this paper is to construct these events for continuous-time processes if they are given for the corresponding discrete-time model. The construction uses so-called renovative events revealing the property of the state at timen of the discrete-time model to be independent (in an algebraic sense) of the states referring to epochs not later thann −L (whereL is some constant) given that there are some restrictions on the “governing sequence”. Different types of multi-server and multi-phase queues are considered.     

Cascade reactions leading to the mechanism of action of vinaxanthone and xanthofulvin,natural products that drive nerve repair

The natural products vinaxanthone and xanthofulvin promote regeneration in animal models of spinal cord injury and corneal transplant. However, inhibition of the initially described biological target of these compounds, semaphorin 3A, does not fully account for the recovery demonstrated in vivo following administration of the natural products. Through chemical synthesis substantial quantities of both natural products have been accessed with early reaction development paving the way for synthesizing both compounds. The success of a model system, first disclosed herein, translated to the syntheses of both natural products. Following from this we also report for the first time the discovery of a new target of the natural products, the succinate receptor 1 (SUCNR1). Both natural products function as positive allosteric modulators of SUCNR1. As the first known allosteric modulators of SUCNR1, the compounds represent powerful new tools to understand the pharmacology of SUCNR1 and its control of growth and cellular defense.     

液氦净化系统的过滤及反吹特性研究

作为一种优良的超导与冷却介质,超高纯液氦在工业以及航空航天等领域中的应用相当广泛。金属丝网过滤器具有理想均匀的孔径分布和优异的流体渗透性能,可适用于高洁净度、高安全性的低温液体净化系统。通过搭建液氦过滤与净化系统实验台,研究了过滤精度为0.5μm的不锈钢丝网过滤器对液氦中固体氮颗粒的过滤特性,探讨了压降及过滤效率的变化规律,以及反吹过程中的升温趋势。结果表明,该过滤器能有效实现液氦的净化。     

Environmentally Friendly Recovery and Characterization of Oil from Used Engine Lubricants

The present paper demonstrates the review of some acid processes as well as development of some new solvent processes for reclamation of used lubricating oils. The conventional processes are found to be of low yield (? 50%), laborious, time consuming and environmentally hazardous, because of residual acidic sludge. Based on the findings, a new modified Aluminium sulphate‐sodium silicate‐acid‐base method employing a small quantity of acid and giving a high yield (? 60%) is proposed. Further, to avoid use of acid, new regeneration processes based on solvent extraction were investigated. They are termed CCl₄‐alcohol method, Dodecane‐alcohol method and Toluene‐alcohol method. These processes are not only cost effective in terms of complete solvent recovery, but are rapid, less time consuming, more environmentally friendly and gave a high yield (70–75%). The virgin lubricants (Castrol GTX and Rimula‐C) as well as oils recovered by different methods were also characterized physicochemically to determine kinematic viscosity, density, refractive index, carbon distribution, wear scar diameter, % Conradson carbon residue, % ash, % chloride, pour point, etc. Results obtained show that many of the physico‐chemical properties of the recovered oils are in good agreement with those of virgin oils. The n.d.M analysis was also performed which shows that virgin oils have 73 ± 3% paraffinic carbon, 26 ± 3% naphthenic carbon and about 1% aromatic carbon. The recovered oils also showed nearly the same chemical composition. The UV‐Visible spectra of the recovered oils are all similar to those of virgin lubricants. The results suggest that the oils recovered by solvent treatments, particularly Dodecan‐alcohol and Toluene‐alcohol methods, may serve for lubrication purposes and can be rendered as excellent as virgin lubricants with the addition of certain additives. The proposed methods may be considered as alternative cost effective green techniques for acid reclamation processes and being the motivation of the present investigation.     

Carrier-mediated extraction of bipyridilium herbicides across the hydrophobic liquid membrane

Supported liquid membrane (SLM) method for preconcentration and enrichment of the two bipyridilium herbicides, namely diquat and paraquat, from environmental water samples has been developed. The permanently charged cationic herbicides were extracted from a flowing aqueous solution to a stagnant acidic acceptor solution across a liquid membrane containing 40% (v/v) di-(2-ethylhexyl) phosphoric acid dissolved in di-n-hexyl ether. The mass transfer of analytes is driven by the counter-coupled transport of hydrogen ions from the acceptor to the donor phase. The efficiency of the extraction process depends on the donor solution pH, the amount of the mobile carrier added to the liquid membrane and the concentration of the counter ion in the acceptor solution. The applicability of the method for extraction of these quaternary ammonium herbicides from environmental waters was also investigated by spiking analyte sample solutions in river water. With 24 h sample enrichment concentrations of diquat and paraquat down to ca. 10 ng/L could be detected in environmental waters.     

天然气和二氧化碳转化制合成气的研究Ⅵ Ni／Al_2O_3催化剂再生的疏活机理

采用γ－Ａｌ_２Ｏ_３为载体，以硝酸镍、硝酸镁和稀土硝酸盐为原料，按常规浸渍法制备镍负载型催化剂，其中Ｎｉ含量为９．１７％，助剂ＲＥ_２Ｏ_３和Ｍｇ含量分别为５．１８％和１．８０％，该催化剂简称为Ｎ－５－ＲＭ。催化反应评价采用双套管石英反应器，在多功能固定床流动反应装置上进行，以天然气和二氧化碳转化为探针反应，采用连续反应法评价催化剂性能。以反应尾气中合成气摩尔百分数表征催化剂活性。采用理光Ｄ／ｍａｘ－ｒ－Ｂ型Ｘ射线衍射仪测定催化剂晶相。实验发现，催化剂长期使用失活的主要原因是由于活性中心Ｎｉ￣０与载体Ａｌ_２Ｏ_３间形成难还原的ＮｉＡｌ_２Ｏ_４物种，以及活性中心Ｎｉ￣０聚集形成晶相，从而降低了催化剂表面活性中心数。ＴＰＲ结果指出，ＮｉＡｌ_２Ｏ_４物种在高温下通氢气可以得到充分还原。然而，此时催化剂活性仍明显低于新鲜催化剂活性。ＸＲＤ结果表明，此时催化剂存在很强的Ｎｉ￣０衍射峰，说明尽管高温还原已使形成ＮｉＡｌ_２Ｏ_４的Ｎｉ￣（２＋）还原为Ｎｉ￣０，但高温还原又进一步使活性Ｎｉ￣０聚集成晶相，因而降低了催化剂表面活性中心数。这说明，对ＮｉＡｌ_２Ｏ_４的活化仅通过常规高温还原是不够的。２０％过氧化氢水溶液（以下简称     

丙烯直接环氧化Au/TiO2催化剂失活及再生研究

采用沉积沉淀法制得Au／TiO2负载型催化剂，研究了该催化剂的丙烯气相直接环氧化合成环氧丙烷的反应性能，对新鲜、失活和再生后的催化剂进行TG-DTA、FT-IR、吡啶-IR、TEM以及活性评价等表征．研究结果表明．催化剂的失活是由于吸附在催化剂表面酸性Ti位上的环氧丙烷产物发生副反应生成了大分子沉积物．该沉积物存在着两种类型，其含有长碳烷基和酯基．催化剂再生实验表明在空气和H2中再生时活性恢复良好，而在N2中的再生效果则很差．     

钙型沸石对生活污水中氨氮去除的研究

通过静态方法研究了钙型沸石对氨氮的去除效果．氨氮在钙型沸石上的吸附是吸热过程，饱和吸附容量是46．29mg／g．经过10次吸附-解析-再吸附循环过程，从吸附容量的数据可知盐酸和氯化钠可以获得很好的再生效果，吸附容量的标准偏差分别为6．34％和6．59％．对生活污水中氨氮的去除效果表明，在废水处理过程中钙型沸石将是一种实用和廉价的氨氮吸附剂。     

Study on the controllable synthesis of SH-MCM-41 mesoporous materials and their adsorption properties of the La3+, Gd3+ and Yb3+

SH-MCM-41 was examined in adsorption and desorption experiments to investigate the adsorption capacities of La³⁺, Gd³⁺ and Yb³⁺ and the reusability.