银纳米粒子-介孔菱沸石-无纺布复合材料的构建及其止血和抗菌性能分析

以无纺布(NW)为基质,采用原位生长法制备了介孔菱沸石-无纺布(mCHA-NW),再以其为载体,复合银纳米粒子(AgNPs),最终得到银纳米粒子-介孔菱沸石-无纺布(AgNPs-mCHA-NW)复合材料.利用X射线衍射(XRD)、场发射扫描电子显微镜(FE-SEM)、X射线光电子能谱仪(XPS)、全自动物理吸附仪(BE...     

沸石转晶的研究(Ⅱ)——T型沸石中毛沸石与菱钾沸石间转换关系的研究

本文采用动态吸附法,定量测定了各种条件下样品中毛沸石与菱钾沸石的含量,并利用化学分析法测定了晶化过程中液相组份含量的变化,从而发现了毛沸石与菱钾沸石间的转换关系及合成它们的最佳条件.     

介孔-微孔复合材料的水热稳定性及其催化裂化性能

采用无模板剂的溶胶凝胶法制备了一系列具有均一介孔和MFI沸石微孔的复合材料.与MCM-41相比,包含silicalite-1沸石结构的复合材料的水热稳定性得到显著改善.1,3,5-三异丙苯的催化裂化反应结果表明,与商品HZSM-5沸石相比,包含ZSM-5沸石结构的复合材料具有更高的催化活性和抗积炭性能.三异丙苯的转化率...     

沸石催化剂上甲醇转化为低碳烯烃的研究 1.改性沸石催化剂的选择性和稳定性的考察

甲醇转化为低碳烯烃催化剂的选择性,可通过由有机胺(79-2系列)或无机氨(HZ-29系列)合成的中孔ZSM-5沸石以及小孔毛沸石和毛沸石-菱钾沸石(HE-1和HSW)的改性而提高。经P(HZ-29-P)或Mg(79-2-Mg)改性的沸石催化剂相应具有高乙烯或高丙烯及低碳烯烃选择性;经改性后的两类小孔沸石(HE-1-Zn 和SW-2)都得到了高乙烯及丙烯选择性和高C_2~-/C_3~-比。改性前后的沸石催化剂经吸附容量、吸附氨TPD、吸附吡啶IR 等测定结果表明,沸石改性后引起的通道收缩及表面强酸中心数的减少是提高选择性的关键。和H 型的对比,在经改性后的沸石催化剂上结炭量都明显下降,其中以HZ-29-P 结炭最少,且此催化剂能够经受30次以上的再生试验。     

异相晶种诱导快速合成低硅菱沸石分子筛

在不含有机模板剂体系(OSDAs)中,利用异相晶种(T型分子筛)诱导快速合成出纯相的低硅菱沸石分子筛。采用XRD、SEM、TEM、27Al MAS NMR和紫外拉曼等手段表征分子筛的结构属性和形貌特点。详细研究了菱沸石分子筛的晶化过程以及晶种添加量、nAl2O3/nSi O2、nH2O/nSiO2和碱度对菱沸石分子筛晶化的影响,并探讨T型分子筛晶种诱导合成菱沸石分子筛的晶化机理。原位合成体系中仅形成L型分子筛晶相,而一定量T型分子筛异相晶种的加入诱导溶胶快速制备出纯相的菱沸石分子筛。T型分子筛晶体在一定的水热条件下不断溶解而释放的六元环(6R)和四元环(4R)迅速形成菱沸石分子筛特征笼(CHA笼),抑制了L型分子筛特征单元和特征笼(不含四元环的CAN笼)的形成。     

锂离子电池负极硅-热解碳-石墨复合材料的制备及性能

以沥青为碳前驱物,通过加热分解法制备了具有不同热解碳含量的硅-热解碳-石墨复合材料,并测试及分析了材料的形貌、结构及电化学性能。结果表明,沥青质量在320～560℃的温度区间内迅速减小,沥青质量的减小是由于氢元素的去除。经过高温分解制得的热解碳与沥青的质量比率为65%。在硅-热解碳-石墨复合材料中,硅颗粒分散在石墨表面,热解碳覆盖在硅颗粒表面,热解碳增强了硅颗粒与石墨间的界面结合力。适当含量的热解碳增大了复合材料的放电比容量且改善了循环稳定性;过量的热解碳不能进一步提升复合材料的放电容量。     

环已胺在沸石分子筛上的吸脱附行为研究

本文以程序升温脱附(TPD)为主要实验手段,对环己胺在5种不同沸石分子筛上的吸脱附行为进行了研究。结果表明,沸石分子筛对环己胺有着较强的吸附作用,不同的沸石分子筛对环己胺的吸附能力受其结构和表面酸性特征的影响而异。有效吸附部位为与沸石分子筛表面酸性有关的弱化学吸附位;环己胺从不同沸石分子筛表面脱附的动力学与晶内扩散有关,其表观脱附活化能分别为:63.6kJ/mol(5A),68.6kJ/mol(13X),20.1kJ/mol(菱沸石),46.9kJ/mol(NaY)和47.3KJ/mol(ZSM-5)。     

一步法制备EVA/MMT纳米复合材料的研究

高聚物／粘土纳米复合材料是现今高分子材料研究中的一大热点、在高聚物基体中填充少量的纳米级粘土便可显著增强其力学性能及热稳定性^[1-3]。高聚物／粘土纳米复合材料的制备通常采用有机改性法即先用长链烷基铵盐将粘土有机化，使粘土片层间距增大，并由亲水性变为亲油     

扎赉特旗油砂在氮气气氛下的热解制油研究

油砂是一种含有沥青或其他重质石油的沉积岩，主要用于提取油砂沥青，以生产合成原油。中国拥有相当数量的油砂资源，目前还未开采，仅处于初步研究阶段。加拿大在20世纪初期就展开了油砂的开采及制油研究工作，并于20世纪70年代由加拿大合成油公司实现了工业化生产。油砂生产的沥青和合成油已占其石油总产量的1／4以上。     

介孔ZSM-5沸石微球催化剂上萘的苄基化反应

以有机硅烷化的二氧化硅为硅源,制备了由纳米粒子聚集而成的、具有晶间和晶内介孔的微球状ZSM-5(MMZ-5)沸石.通过吡啶(Py)和2,6-二叔丁基吡啶(DTBPy)在介孔沸石表面吸附的原位红外测试,对其酸性进行了表征.与微孔ZSM-5沸石相比,MMZ-5沸石上的Lewis酸位和总酸位增加,特别是探针大分子DTBPy(动力学直径约为1.05 nm)可及的Br?nsted酸位显著提高.萘在MMZ-5沸石上的苄基化催化结果表明,反应发生在拥有大量活性位的沸石外表面,大的沸石外表面为该催化反应提供了作用空间,从而提高了沸石活性位的有效利用率,使MMZ-5沸石上萘的苄基化反应活性显著提高,能够生成大分子产物一苄基萘和二苄基萘;其中,一苄基萘的选择性约为79%,且随着反应时间的延长,MMZ-5沸石大的晶内介孔(3-5 nm)为反应提供了有效反应空间,促进一苄基萘向二苄基萘转化.异构体α-一苄基萘和β-一苄基萘的摩尔比值约为83:17,该值不随着温度和转化率的变化而改变.     

Bitumen upgrading under solvothermal/hydrothermal conditions

Bitumen is known as a mixture of organic liquids which has great importance to the chemical industry because of its great variety of special properties, which has favored the development of a wide field of applications. Bitumen has been mainly obtained as a residue of the petroleum refining process. Recently, the development of a process has been proposed to recover chemical resources from bitumen that can accomplish the destruction of the bitumen to produce harmless but useful compounds. Water at hydrothermal conditions is considered a promising and an environmentally acceptable solvent for a wide variety of chemical reactions such as organic syntheses and decomposition of hazardous waste into harmless compounds. In these works, water at supercritical conditions was applied as a solvent for upgrading of bitumen. The experiments were conducted at a temperature of 673 K and at various reaction pressures. The effect of pressure and reaction time on the decomposition process is presented. The chemical species in the aqueous products were analyzed by gas chromatography?Cmass spectrometry and matrix-assisted laser desorption ionization time-of-flight mass spectroscopy. Ultimate analysis of solid residue was also conducted using a CHN analyzer. The results showed that the amounts of bitumen-derived compounds formed increased with increasing reaction time. In addition, the study of bitumen model compounds by using a batch reactor was also conducted. Furthermore, this method could become an efficient method for upgrading bitumen into harmless compounds with a high yield of valuable chemical intermediates on the basis of the experimental results.     

Synergistic effect of water layer and divalent metal ions in a model oil sand on bitumen liberation from solids surface

In this work, we offer a direct evidence to illustrate the synergistic effect of water layer and divalent metal ions in oil sands on bitumen liberation from solids surface. A model oil sand was constructed by coating bitumen on the glass surface with a water layer containing divalent metal ions inserted between them. The bitumen liberation behaviors were investigated by placing the model oil sands in various pH solutions. It was found that the water layer facilitated the bitumen liberation, while the presence of Ca²⁺ or Mg²⁺ in the water layer played a different role on the bitumen liberation depending on the solution pH. It was believed that the variation of the bitumen liberation was attributed to the changes of surface wettability arising from the adsorption of natural surfactants on the solids and bitumen surfaces. The preferential adsorption of Ca²⁺ or Mg²⁺ on the solids and bitumen surfaces acted as either a barrier to disturb the cationic surfactants adsorbing or a bridge to anchor the anionic surfactants. The findings in this work are important for understanding the bitumen liberation behaviors and give a guideline of how controlling the water chemistry when processing the oil sands by water-based bitumen extraction processes.     

Copolymerization of styrene with vinyl acetate in a construction petroleum bitumen medium and properties of obtained composite materials

The regularities of the copolymerization of styrene (Sr) with vinyl acetate (VA) in a construction petroleum bitumen (CPB) medium are studied. It is established that, in the bitumen medium, the superiority of styrene in terms of reactivity when compared to vinyl acetate is not expressed as critically as in the case of in-bulk copolymerization. Polymer-bitumen composite materials with improved operating performance as compared to bitumen were obtained by copolymerization.     

Surface microstructure of bitumen characterized by atomic force microscopy

Bitumen, also called asphalt binder, plays important roles in many industrial applications. It is used as the primary binding agent in asphalt concrete, as a key component in damping systems such as rubber, and as an indispensable additive in paint and ink. Consisting of a large number of hydrocarbons of different sizes and polarities, together with heteroatoms and traces of metals, bitumen displays rich surface microstructures that affect its rheological properties. This paper reviews the current understanding of bitumen's surface microstructures characterized by Atomic Force Microscopy (AFM). Microstructures of bitumen develop to different forms depending on crude oil source, thermal history, and sample preparation method. While some bitumens display surface microstructures with fine domains, flake-like domains, and dendrite structuring, ‘bee-structures’ with wavy patterns several micrometers in diameter and tens of nanometers in height are commonly seen in other binders. Controversy exists regarding the chemical origin of the ‘bee-structures’, which has been related to the asphaltene fraction, the metal content, or the crystallizing waxes in bitumen. The rich chemistry of bitumen can result in complicated intermolecular associations such as coprecipitation of wax and metalloporphyrins in asphaltenes. Therefore, it is the molecular interactions among the different chemical components in bitumen, rather than a single chemical fraction, that are responsible for the evolution of bitumen's diverse microstructures, including the ‘bee-structures’. Mechanisms such as curvature elasticity and surface wrinkling that explain the rippled structures observed in polymer crystals might be responsible for the formation of ‘bee-structures’ in bitumen. Despite the progress made on morphological characterization of bitumen using AFM, the fundamental question whether the microstructures observed on bitumen surfaces represent its bulk structure remains to be addressed. In addition, critical technical challenges associated with AFM characterization of bitumen surface structures are discussed, with possible solutions recommended. For future work, combining AFM with other chemical analysis tools that can generate comparable high resolution to AFM would provide an avenue to linking bitumen's chemistry to its microscopic morphological and mechanical properties and consequently benefit the efforts of developing structure-related models for bituminous materials across the different length scales.     

Leaching studies of137Cs from ion-exchange resin incorporated in cement or bitumen

Leaching of¹³⁷Cs from ion-exchange resin incorporated in cement and bitumen composite using two methods based on theoretical equations has been developed. These were: Method I, diffusion equation derived for a plane source model¹ and Method II, empirical model employing a polynominal equation^2,3. Results presented in this paper are examples of data obtained in a cement and bitumen testing project which will influence the design of a future radioactive waste storage center.     

加拿大油砂沥青减压渣油在CO/H2-H2O作用下的热改质特性研究

以加拿大油砂沥青大于420℃的减压渣油（BVR）为原料,对比研究其在CO/H₂-H₂O和N₂体系中的热改质特性,通过系统分析BVR在H₂-H₂O、CO-H₂O、N₂-H₂O等不同氢源下的热改质特性以揭示CO/H₂-H₂O对渣油热改质的作用机制,最后探讨合成气压力、含水量以及温度对BVR临CO/H₂-H₂O改质生焦倾向的影响。结果表明,与临氮改质相比,相同反应条件下,合成气和水可使BVR热改质的生焦诱导期延长3.5-6.5 min;相同生焦率（约0.1%）时,合成气和水可显著提升BVR热改质降黏率,410℃时相对临氮改质的降黏率为29.1%,而420℃时可达54.6%。比较不同氢源下BVR热改质的生焦诱导期、改质油黏度和安定性、渣油转化率发现,H₂-H₂O、CO-H₂O、N₂-H₂O等均对BVR热改质表现出与CO/H₂-H₂O相同的促进效果,各氢源作用活性的大小顺序为H₂-H₂O > CO/H₂-H₂O > CO-H₂O > N₂-H₂O。由此可知,CO/H₂-H₂O对渣油热改质的促进作用可归因于氢气、CO水热变换新生氢和水热裂解的综合效应,且其中氢气的作用仍最显著。合成气压力、含水量和反应温度可通过影响不同氢源的贡献而调控BVR临CO/H₂-H₂O改质生焦倾向。低成本易获取的合成气可以提供BVR热降黏改质所需氢源,水能够通过CO水热变换反应供出新生活泼氢而协同合成气实现BVR高效改质。     

Disjoining pressure isotherms of water-in-bitumen emulsion films

In the oil sands industry, undesirable water-in-oil emulsions are often formed during the bitumen recovery process where water is used to liberate bitumen from sand grains. Nearly all of the water is removed except for a small percentage (approximately 1 to 2%), which remains in the solvent-diluted bitumen as micrometer-sized droplets. Knowledge of the colloidal forces that stabilized these water droplets would help to increase our understanding of how these emulsions are stabilized. In this study, the thin liquid film-pressure balance technique has been used to measure isotherms of disjoining pressure in water/toluene-diluted bitumen/water films at five different toluene-bitumen mass ratios. Even though a broad range of mass ratios was studied, only two isotherms are obtained, indicating a possible change in the molecular orientation of surfactant molecules at the bitumen/water interfaces. At low toluene-bitumen mass ratios, the film stability appears to be due to a strong, short-range steric repulsion created by a surfactant bilayer. Similar isotherms were obtained for water/toluene-diluted asphaltene/water films, indicating that the surface active material at the interface probably originated from the asphaltene fraction of the bitumen. However, unlike the bitumen films, films of toluene-diluted asphaltenes often formed very rigid interfaces similar to the "protective skin" described by other researcher.     

Adhesion of single polyelectrolyte molecules on silica, mica, and bitumen surfaces

In a recent study (Energy Fuels 2005, 19, 936), a partially hydrolyzed polyacrylamide (HPAM) was used as a process aid to recover bitumen from oil sand ores. It was found that HPAM addition at the bitumen extraction step not only improved bitumen recovery but also enhanced fine solids settling in the tailings stream. To understand the role of HPAM, single-molecule force spectroscopy was employed for the first time to measure the desorption/adhesion forces of single HPAM molecules on silica, mica, and bitumen surfaces using an atomic force microscope (AFM). Silicon wafers with an oxidized surface layer and newly cleaved mica were used, respectively, to represent sand grains and clays in oil sands. The force measurements were carried out in deionized water and in commercial plant process water under equilibrium conditions. The desorption/adhesion forces of HPAM obtained on mica, silica, and bitumen surfaces were approximately 200, 40, and 80 pN in deionized water and approximately 100, 50, and 40 pN in the plant process water, respectively. The measured adhesion forces together with the zeta potential values of these surfaces indicate that the polymer would preferentially adsorb onto clay surfaces rather than onto bitumen surfaces. It is the selective adsorption of HPAM that benefits both bitumen recovery and tailings settling when the polymer was added directly to the bitumen extraction process at an appropriate dosage.     

The behaviour of micro-bitumen drops in aqueous clay environments

This study summarises the rheological behaviour of emulsion bitumen drops in the presence of aqueous solutions of de-ionised or process water (DIW or PW) containing montmorillonite clays (M) and/or calcium ions (Ca++). The presence of calcium ions and montmorillonite clays resulted in the plastic behaviour of bitumen drops. In a DIW+M+Ca++ system, increasing temperature and calcium ion concentration resulted in an increase in the number and degree of plastic bitumen drops. In the presence of considerable amounts of Ca++ ions and/or at higher experimental temperature, bitumen drops in a PW+M system exhibited no significant overall plasticity of their surfaces. Both calcium and sodium ions contained in process water compete with each other to occupy the montmorillonite clay surface. At the pH value of process water (pH congruent with8), increasing the temperature did not change the value of bitumen droplet zeta potential. Stability of bitumen-in-water emulsions at 22 degrees C showed that bitumen droplets coalesced upon contact in the DIW+M system. The addition of calcium ions (Ca++) led to the inhibition of coagulation and coalescence of bitumen droplets, which may indicate the formation of CaM aggregates at the bitumen-water interface.     

Interaction forces in bitumen extraction from oil sands

Water-based extraction process (WBEP) has been successfully applied to bitumen recovery from Athabasca oil sand ore deposits in Alberta. In this process, two essential steps are involved. The bitumen first needs to be "liberated" from sand grains, followed by "aeration" with air bubbles. Bitumen "liberation" from the sand grains is controlled by the interaction between the bitumen and sand grains. Bitumen "aeration" is dependent, among other mechanical and hydrodynamic variables, on the hydrophobicity of the bitumen surface, which is controlled by water chemistry and interactions between bitumen and fine solids. In this paper, the interaction force measured with an atomic force microscope (AFM) between bitumen-bitumen, bitumen-silica, bitumen-clays and bitumen-fines is summarized. The measured interaction force barrier coupled with the contacted adhesion force allows us to predict the coagulative state of colloidal systems. Zeta potential distribution measurements, in terms of heterocoagulation, confirmed the prediction of the measured force profiles using AFM. The results show that solution pH and calcium addition can significantly affect the colloidal interactions of various components in oil sand extraction systems. The strong attachment of fines from a poor processing ore on bitumen is responsible for the corresponding low bitumen flotation recovery. The identification of the dominant non-contact forces by fitting with the classical DLVO or extended DLVO theory provides guidance for controlling the interaction behavior of the oil sand components through monitoring the factors that could affect the non-contact forces. The findings provide insights into megascale industrial operations of oil sand extraction.