负载型CuCl的NO分解性能

制备并研究了几种负载型ＣｕＣｌ体系中ＣｕＣｌ的分散状态及其ＮＯ分解性能。结果表明,单层分散对于负载型ＣｕＣｌ体系的Ｎ粉解性能起着重要作用。ＣｕＣｌ含量在其分散阈值附近的样品具有最高的ＮＯ解解活性。     

高载量、高活性Ni/Al2O3催化剂的制备及其芳环加氢催化反应

使用共沉淀法制备了担载量很高的Ni/Al2O3催化剂,通过正丁醇干燥处理,提高了催化剂的表面积和担载镍的分散度.实验发现,镍的担载量和干燥过程刘催化剂的表面积、孔结构及金属镍的还原度和分散度影响很大.经过正丁醇处理的80%Ni/Al2O3-B催化剂具有较高的表面积,而担载镍的还原度和分散度也显著提高,使得催化剂具有很高...     

Peculiarities of the surface crystallization of sodium chloride on mucin films

It is established that the two-dimensional crystallization of sodium chloride on the surface of a biopolymer film (film of a glycoprotein, mucin), which is used as a template, gives rise to the formation of crystals with unusual morphology—in particular, dendrites. This type of crystallization is observed in two cases—namely, when drying a film formed from a salt-containing mucin dispersion and when drying a salt solution droplet on the surface of a dry mucin film obtained from a salt-free mucin dispersion. Mechanisms leading to unusual salt crystallization are discussed, and the role of specific interactions of sodium chloride with mucin is shown.     

Effect of drying methods on the structure and catalytic combustion activity of Mn-substituted hexaaluminate catalysts

Conventional oven drying (COD) and supercritical drying (SCD) methods were applied to the preparation of Mn-substituted hexaaluminate (BaMnAl₁₁O_19-α) catalysts. The effect of drying methods on phase composition, specific surface area, pore structure and combustion activity of the samples was investigated. The samples obtained by SCD have higher surface area, narrower pore size distribution, and higher combustion activity than those obtained by COD. This revised version was published online in August 2006 with corrections to the Cover Date.     

单分散聚苯乙烯微球的制备及表征

应用膜乳化-液中干燥法成功制备出粒径为2～20μm的单分散聚苯乙烯(PS)微球.PS微球的粒径主要由膜孔径决定,其值约为膜孔径的2倍;PS溶液的浓度对其也有一定的影响.膜乳化过程中的压力对微球粒径的分散性有很大的影响,在一定压力范围内,粒径呈单分散.在分散相中加入致孔剂,制备出表面多孔的PS微球.采用复乳-液中干燥法制备出中空PS微球.     

Influence of drying procedure on the mesoporosity and surface fractal dimensions of silica xerogels prepared with different agitation methods

Silica xerogels were prepared by thermal drying wet gels in an electric oven (70 degrees C) after certain duration of ambient drying, and the relevant effect is investigated on the mesopore structures and surface fractal dimensions of the resultant xerogels. The silica gels were derived from a hydrochloric acid-catalyzed TEOS (tetraethylorthaosilicate) system, and both magnetic stirring and ultrasonic vibration were adopted during sol preparation. The percentage mesoporosity and surface fractal dimensions are evaluated using image analysis methods, based on FE-SEM (field emission gun-scanning electron microscopy) images. The results show that the mesoporosity of the resultant xerogels decreases with the duration of ambient drying for samples prepared using magnetic stirring and low-intensity ultrasonic vibration, while samples subjected to high-intensity ultrasound show a somewhat reverse trend. Samples prepared with magnetic stirring have almost constant surface fractal dimensions (nearly 3), irrespective of the ambient drying before thermal drying. The surface fractal dimensions of samples prepared using ultrasound increase with the duration of ambient drying.     

Improved polyvinylpyrrolidone (PVP)/graphite nanocomposites by solution compounding and spray drying

In order to evaluate the roles of graphite dispersion on the functional properties of the composites, PVP/graphite nanocomposites were prepared by blending the aqueous suspension of expanded graphite sheets and polyvinylpyrrolidone (PVP) aqueous solution by ultrasonic treatment, followed by spray drying and direct drying as a comparison individually. The effects of graphite loading and drying method on the dispersion of graphite and the resultant properties of the composites such as electrical and thermal conductivity, friction, and dynamic mechanical properties were studied. The results from transmission electron microscopy (TEM), scanning electron microscopy (SEM), and X‐ray diffraction showed that the composites prepared by fast spray drying exhibited a higher degree of exfoliation and a better dispersion of graphite sheets in the PVP matrix than the corresponding composites prepared by direct drying, leading to a conclusion that fast spray drying can effectively prevent from re‐stacking of the exfoliated graphite sheets as illustrated. As a result, dynamic mechanical thermal analysis showed significant increases in the storage modulus and glass transition temperature for the composites prepared by spray drying. Besides, the spray drying as well greatly improved the electrical and thermal conductivity of the composites. It was also found that the electrical and thermal conductivity of the composites strongly depended on the graphite dispersion, while the friction coefficient unexpectedly does not. Increasing graphite loading level might enhance the probability of graphite sheets re‐stacking, resulting in poor graphite dispersion. Copyright © 2011 John Wiley & Sons, Ltd.     

Process of drying a polymeric paint by diffusion-evaporation and shrinkage. Determination of the concentration-dependent diffusivity

The process of drying a paint made of a dispersion of a polymer in a solvent is experimentally and theoretically studied at various constant temperatures. The diffusion of the solvent through the paint and evaporation from the surface is considered, as well as the subsequent shrinkage. From measurements made at the beginning and at the end of the drying operation on the kinetics of drying, the diffusivity is found to largely depend on the solvent concentration. An exponential relationship of the diffusivity versus the concentration is thus found and successfully tested for the whole process of drying, the diffusivity increasing with the solvent concentration.     

Controlling wrinkles and assembly patterns in dried graphene oxide films using lyotropic graphene oxide liquid crystals

We fabricated graphene oxide (GO) films on glass substrates by blade coating a lyotropic GO liquid crystal dispersion. Substrate temperature and blading speed were precisely controlled to manipulate the surface morphologies of GO films. The temperature and blade speed influenced the drying rate of film and the amount GO dispersion supplied. By controlling these parameters, film-thickness modulation and three types of surface wrinkle patterns were selectively achieved. We also plotted the wrinkle patterns diagram as functions of the film fabrication conditions. The films exhibited different optical anisotropies depending on wrinkle patterns. GO films with controlled wrinkles can be used as electrodes for supercapacitor applications owing to the large surface areas.     

载体制备方法对合成甲醇催化剂的影响

通过比较以超临界干燥法和以普通空气中干燥得到的氧化锆为载体的ＣｕＯ／ＺｒＯ２催化剂，发现前者对ＣＯ／２Ｈ２合成甲醇的活性优于后者。ＸＲＤ和ＴＰＲ结果表明以超界干燥法制得的氧化锆为载体的催化剂ＣｕＯ的分散度比空气中干燥所得的氧化锆为载体的催化剂高。     

The influence of sodium ethene sulphonate comonomer on the film formation process of poly(vinyl acetate) dispersions

Various latex dispersions from vinyl acetate/sodium ethene sulphonate (sodium vinyl sulphonate) copolymers, stabilised by a constant amount of Hostapal BV, a surfactant with poly(ethylene oxide) groups, were investigated by a variety of solid and liquid state nuclear magnetic resonance methods. In order to investigate the influence of sodium ethene sulphonate on the film formation process, the serum and polymer were analysed separately. The stoichiometric monomer composition of the copolymer in the aqueous phase and in the hydrophobic particles was obtained. The ionic comonomer is enriched at the particle surface via its proximity to the applied surfactant by two-dimensional exchange NMR. For investigations of the film formation process, latex dispersions were prepared and dried to form spatially homogeneous films at different defined solid contents. Depending on the chemical composition of a chosen dispersion, NMR allows the investigation of the drying process of the water. The drying process is a function of the ionic strength of the dispersion and the hydrophilicity of the polymer. It is correlated to the drying mechanism of the water within the film. A not fully dried film contains external water outside the particles, water at ionic and non-ionic groups at surfactants in the polymer water interface and, additionally, water in the swollen and mobilised polymer. The distribution of water to these environments is markedly changed by the ionic comonomer, especially close to the end of the drying process.     

Effect of drying temperature and blanching on the degradation of chlorophyll a and b in mint (Mentha spicata Huds.) and basil (Ocimum basilicum): Analysis by high performance liquid chromatography with photodiode array detection

Summary The effect of drying conditions on the preservation of chlorophyll pigments in mint and basil have been investigated in order to determine the effects of drying temperature and whether or not there was a prior blanching.Pigments extracted from fresh and dried samples were analyzed by reversed phase high performance liquid chromatography coupled to a photodiode array detector; isocratic separation was performed on a Zorbax ODS C18 column.The purity of the chromatographic peaks of chlorophylls and breakdown products was investigated. The visible spectra of standard samples of chlorophylls and pheophytins were compared, using least squares normalization with those of peaks from the extracts of fresh and dried mint and basil. The study has shown that chlorophylls were better preserved when drying was preceded by a short blanching; if samples were not blanched before drying, the degradation of chlorophylls a and b was best prevented by drying at low temperatures.     

用EXAFS方法研究双功能催化剂NiO-MoO3/γ-A2O3的表面分散那

The surface dispersion of bifunctional NiO-MoO_3/γ-alumina catalysts prepared by different procedures was studied with Ni-K EXAFS spectroscopy. The contents of NiO(13.6%) and MoO_3(16.5%) were the same in the three samples, which were a little higher than the monolayer dispersion capacity of each component on γ-Al_2O_3. The dispersion temperature was 450 ℃. The sample impregnated with NiO first shows that the NiO is monolayer-dispersed on γ-Al_2O_3 surface and the outer layer is MoO_3. The sample impregnated with MoO_3 and the outer layer is NiO. There is strong interaction between MoO_3 and γ-Al_2O_3 which affects the dispersion of NiO on the surface. The sample impregnated with NiO and MoO_3 simultaneously shows that the Ni is not dispersed in the form of NiO but another compound on the surface.     

ZnO在NaY沸石表面的分散研究

利用ＸＲＤ、Ｒａｍａｎ光谱分析了影响ＺｎＯ在ＮａＹ表面分散的各种因素，发现延长干燥时间和多次浸渍能促进ＺｎＯ的分散，测量ＺｎＯ的最大分散量为０．４６ｇ／ｇＮａＹ，已远大于文献结果。与模型估算值进行了比较分析，探讨了ＺｎＯ在分子筛内表面的排布状态。     

Ba、Mn对Al2O3热稳定性和甲烷催化燃烧活性的影响

采用溶胶-凝胶法制备BaO•6Al2O3系列催化剂.考察了Ba、Mn的引入对Al2O3的热稳定性及甲烷催化燃烧性能的影响.结果表明, Ba在高温下与Al2O3首先生成BaAl2O4，然后进一步与Al2O3反应生成具有β-Al2O3结构的BaAl12O19六铝酸盐，抑制了Al2O3进一步的烧结，提高了催化剂的热稳定性. Mn的引入也能够促进六铝酸盐的生成并提高催化剂的甲烷燃烧活性.采用超临界干燥法可抑制干燥过程中因毛细收缩引起的比表面积降低.所制备的BaMnAl11O19催化剂经1200 ℃焙烧4 h后，比表面积为35.1 m2•g－1，在空速40000 h－1条件下，10％甲烷转化温度(T10％)为500 ℃，催化活性明显高于常规干燥法制备的相应催化剂.     

原位担载型煤直接液化催化剂的表征

 通过原位担载法将铁系催化剂担载于煤表面,考察了催化剂前驱体的相态、配位环境以及在载体表面的分散状态．采用X射线吸收精细结构和X射线衍射法对原位担载型铁系催化剂前驱体进行了表征．结果表明,催化剂前驱体在煤表面以非晶态、高分散的形式存在,其化学组成主要为FeOOH,且催化剂前驱体的分散程度与载体煤的物理化学性质有关．     

Effect of soluble polymer binder on particle distribution in a drying particulate coating

Soluble polymer is frequently added to inorganic particle suspensions to provide mechanical strength and adhesiveness to particulate coatings. To engineer coating microstructure, it is essential to understand how drying conditions and dispersion composition influence particle and polymer distribution in a drying coating. Here, a 1D model revealing the transient concentration profiles of particles and soluble polymer in a drying suspension is proposed. Sedimentation, evaporation and diffusion govern particle movement with the presence of soluble polymer influencing the evaporation rate and solution viscosity. Results are summarized in drying regime maps that predict particle accumulation at the free surface or near the substrate as conditions vary. Calculations and experiments based on a model system of poly(vinyl alcohol) (PVA), silica particles and water reveal that the addition of PVA slows the sedimentation and diffusion of the particles during drying such that accumulation of particles at the free surface is more likely.     

Thinning of drying latex films due to surfactant

Lateral non-uniformities in surfactant distribution in drying latex films induce surface tension gradients at the film surface and lead to film thinning through surfactant spreading. Here we investigate the influence of the surfactant driven to the air-water interface, during the early stages of latex film drying, on the film thinning process which could possibly lead to film rupture. A film height evolution equation is coupled with conservation equations for particles and surfactant, within the lubrication approximation, and solved numerically, to obtain the film height, particle volume fraction, and surfactant concentration profiles. Parametric analysis identifies the effect of drying rate, dispersion viscosity and initial particle volume fraction on film thinning and reveals the conditions under which films could rupture. The results from surface profilometry conform qualitatively to the model predictions.     

单分散聚苯乙烯乳液高温成膜过程的形态观察

单分散乳液指微粒具有相同化学组成、粒径及界面性质等特征的分散体系 ,因其颗粒均一 ,结构可调 ,赋予了其很多独特性质 ,广泛应用于计量、电子、生物、分析、医学、化工和信息等领域 .同时 ,单分散微粒体系作为研究原子或分子结晶过程的模型物 [1] ,在凝聚态物理中具有重要作用 .单分散乳液在一些条件下能排列成最大密堆积规整结构 ,从而赋予乳胶膜更优异的性能 [2 ] .因此 ,研究单分散乳液的成膜过程 ,在基础理论和实际应用中具有重要意义 .软的乳胶微粒玻璃化温度在室温附近 ,它们在常温下就可形变融合成膜 ,此时水蒸发速度较慢 ,乳液中…     

异丁烷脱氢催化剂V-O-Al水热-流体干燥法合成

负载型 V2 O5催化剂被广泛应用于烃的氧化、低碳烃的氧化脱氢及 NOx的 NH3 还原等催化反应[1～ 3 ] .对于低碳烃脱氢 ,Cr2 O3 和 Pt体系研究较多 ,而 V2 O5体系则鲜有报道[4 ,5] .水热合成方法是合成各种分子筛的常用方法 ,同时也被广泛用于合成多种无机功能材料 (如纳米材料 ,