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以乙酰丙酮钯、乙酰丙酮铜为金属前驱体,以氧化铝球为载体,采用超临界流体沉积法(SCFD)制备氧化铝球负载的平均粒径≤10 nm的钯铜纳米粒子。采用高角度环形暗场-扫描透射电子显微镜(HAADF-STEM)、X射线衍射(XRD)和称重法对钯铜纳米粒子的负载状况、粒径分布进行表征。结果表明,沉积温度与沉积压力对钯铜纳米粒子的粒径有重要影响,在65 ℃、15 MPa时,钯铜纳米粒子的平均粒径可达2.37 nm。在金属前驱体投料量一定时,沉积时间存在最佳值。助溶剂的选择影响钯铜纳米粒子的平均粒径与粒径分布,在65 ℃、15 MPa下,使用8 mL二氯甲烷作为助溶剂,钯铜纳米粒子的平均粒径降至1.81 nm。随着Pd理论负载量的增加,钯铜纳米粒子的平均粒径先降后增,当Pd理论负载量为0.50%时,出现最小值1.81 nm。 相似文献
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超临界流体干燥技术制备纳米二氧化锰 总被引:1,自引:0,他引:1
采用溶胶法和超临界流体干燥技术,在533K,7.6MPa的条件下,用超临界乙醇作为干燥剂制备纳米级二氧化锰,采用X射线衍射,透射电镜确定了二氧化锰粒子的行貌和粒径,结果表明,用超临界流体干燥技术可以得到颗粒细,大小均匀,抗团聚非常好的纳米粒子。 相似文献
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利用超临界流体快速膨胀法(RESS)制备微细颗粒,是近年来兴起的一种很有应用前景的新的粉体技术。笔者就该技术的过程原理、典型实验装置、过程条件的影响因素、近年来国内外的主要研究成果及其存在的问题进行了论述。 相似文献
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超临界流体以其低黏度、高密度、优异的传递性质等在许多领域具有广阔的应用前景。纳米磁性氧化铁微粒在磁性液体、生物医学、催化、电子等许多领域极具应用价值。本文主要综述了超临界流体技术包括超临界溶液快速膨胀法、超临界反溶剂法、超临界干燥法和超临界水热合成法等用于纳米磁性氧化铁制备的国内外研究概况、研究重点以及存在的主要问题,并提出了今后的研究方向。 相似文献
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超临界流体干燥技术制备NiO-SiO2二元纳米材料及其结构特征 总被引:4,自引:1,他引:4
简要介绍了超临界流体干燥技术的发展及其基本原理, 着重阐述了采用溶胶-凝胶(sol-gel)法和超临界流体干燥技术制得的NiO-SiO2二元纳米材料的组成对其结构的影响规律.用比表面与孔隙度分析仪、TEM等分析手段研究了这种复合材料的结构特性.结果发现在NiO-SiO2二元纳米材料中, 随着NiO含量的不断提高, 二元纳米材料的比表面积和孔体积不断减小, 而堆密度和孔尺寸不断变大, 同时显微形貌由纤维放射状、束状变为椭圆状并逐渐过渡到颗粒更大的圆球状. 相似文献
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超临界流体在超细粉体制备中的应用 总被引:18,自引:1,他引:18
对超临界流体用于制备超细粉体的研究现状和主要研究成果进行了综述。介绍了近年来开发的一些新方法和新工艺 ,其中包括超临界溶液快速膨胀 (RESS)法 ,超临界流体脱溶 (SAS)法 ,超临界逆向结晶 (SRC)法 ,超临界干燥 (SD)法和超临界流体化学反应等。分析了这些新工艺新方法的原理、特点 ,技术上的可行性 ,应用前景 ,目前达到的水平与存在的问题 ,及今后发展需解决的关键问题等。 相似文献
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Jerzy Bałdyga Dominik Kubicki Boris Y. Shekunov Keith B. Smith 《Chemical Engineering Research and Design》2010
The process termed solution enhanced dispersion by supercritical fluids (SEDS™) is investigated. In the process particles are created in the rapid antisolvent process using a twin-fluid nozzle to co-introduce the SCF antisolvent and solution. Results of experimental and numerical studies are presented for two regions of pressure: above the mixture critical pressure where a single-phase exists for all solvent–antisolvent compositions, and below the mixture critical pressure where the two-phase region is observed. In experimental studies paracetamol (in the single-phase system) and nicotinic acid (in the two-phase system) were precipitated from ethanol solution using supercritical CO2 as an antisolvent. To interpret the phenomena affecting creation of the supersaturation and to predict suprsaturation distribution, balances of momentum (flow), species (mixing), energy (heating and cooling) and population (droplet and crystal size distributions) are applied. The Favre averaged k–? model of the CFD code FLUENT is applied together with specific models for precipitation subprocesses and Peng–Robinson equation of state. This includes application of the PDF closure procedure for precipitation and the drop breakage kernel that is based on multifractal theory of turbulence for modelling drop dispersion. Thermodynamic effects of mixing and decompression are included as well. Predicted values not always agree with experimental data but anyhow simulations predict all trends observed in experiments. 相似文献
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设计了预成膜二流式喷嘴用于超临界流体强制分散溶液(SEDS)过程以获得良好的雾化与传质效果。采用预成膜雾化的SEDS(SEDS-PA)过程对胡萝卜素、麻黄素及黄芩甙进行了超细和聚合物包覆实验以考察该法制备药物微粒和载药聚合物微粒的有效性。通过SEM及光学显微镜照片分析微粒形态,用分光光度法检测药物在聚合物微粒中的含量。实验表明,通过SEDS-PA过程可成功地对天然药物超细化,并用聚合物对其包覆,从而制备药物微粒及载药聚合物微粒。 相似文献
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溶解度参数法计算超临界流体的溶解度 总被引:1,自引:0,他引:1
溶质在超临界流体中的溶解度计算方法有热力学模型和经验公式2种,其中经验公式法形式简单,精度接近甚至高于热力学模型,应用广泛。以往的经验公式多用超临界流体密度来关联溶解度,文中选择以溶解度参数为变量,用3个与温度无关的可调参数,建立了超临界流体溶解度计算的经验公式。计算的11种固体在超临界CO2、乙烷和乙烯中溶解度与实验数据的平均相对误差在10%左右。与密度相比,溶剂与溶质的溶解度参数差更能直观地反映出超临界流体对物质的溶解能力,且具有明确的理论基础,应该引起足够的重视和推广。 相似文献
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Generation of PEEK-WC membranes by supercritical fluids 总被引:2,自引:0,他引:2
S. Cardea A. Gugliuzza E. Schiavo Rappo M. Aceto E. Drioli E. Reverchon 《Desalination》2006,200(1-3):58-60
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以Fe质量分数分别为0.3%、1.6%、3.3%和5.2%的氯化钠担载铁为催化剂,化学气相沉积法催化裂解乙炔400℃下进行反应,系统探讨了碳包覆金属纳米颗粒的可控制备。通过扫描电子显微镜和高分辨透射电子显微镜对产物进行了表征,结果表明,w(Fe)=0.3%的催化剂制备的样品粒径在20~50 nm,平均直径约为30 nm;w(Fe)=1.6%的催化剂制备的样品粒径在35~60 nm,平均直径约为49 nm;而w(Fe)=3.3%和5.2%的催化剂制备的样品粒径差别不大,在40~100 nm,平均粒径约为65 nm。所制备的碳包覆金属纳米颗粒具有清晰的同心石墨壳层结构,并存在一定的结构缺陷。 相似文献
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In the study of the possible coke removal from zeolite catalysts, the solubility of polyaromates in supercritical fluids (SCF) was determined, showing that it becomes drastically reduced with increasing molar mass. Experiments with supercritical ethyl benzene and benzene showed that only coke precursors can be dissolved and, therefore, complete coke removal by SCF is impossible but it has been confirmed that, under supercritical conditions, deactivation of the catalyst could be slowed down. 相似文献
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The solubilities of several low-volatility compounds in supercritical fluids were measured. The fluids used were pure carbon dioxide or carbon dioxide modified with small amounts of organic liquids. Some enthalpies of solution of solids in carbon dioxide at a density of 0.80 g/mL are presented. The enthalpy of solution of fluoranthene in carbon dioxide was found to be less endothermic at higher CO2 density. The order of solubilities in the modified fluids was the same as that in the pure liquid modifiers. The same apparatus was used to measure vapor pressures of some substances as well as solubilities. 相似文献
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全灿 《中国化学工程学报》2009,17(2):344-349
Based on the solubility in supercritical CO2, two strategies in which CO2 plays different roles are used to make quercetine and astaxanthin particles by supercritical fluid technologies. The experimental results showed that micronized quercetine particles with mean particle size of 1.0-1.5 µm can be made via solution enhanced dis-persion by supercritical fluids (SEDS) process, in which CO2 worked as turbulent anti-solvent; while for astaxan-thin, micronized particles with mean particle size of 0.3-0.8 µm were also made successfully by rapid expansion supercritical solution (RESS) process. 相似文献