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1.
C.H. BARTHOLOMEW G.D. WEATHERBEE G.A. JARVI 《Chemical Engineering Communications》2013,200(1-4):125-134
The effects of carbon formation on methanation activity of nickel and nickel bimetallic catalysts were investigated. Carbon was deposited on these catalysts at 675-700 K, 1 atm, H2/CO = 2 and space velocities of 80,000 to 200,000 h?1 over a period of 6-24 hours. Specific methanation activities were measured before and after carbon depositing treatments at 500-575 K, 1 atm H2/CO = 4 and space velocities of 100,000 h?1. The results show that Ni/Al2O3 loses 20-60% of its initial activity within 10-15 hours of treatment. Platinum and cobalt promoted nickel are significantly more resistant to deactivation by carbon. However, Ni-MoO2 is highly susceptible to deactivation, losing essentially all of its activity within a few hours. Data showing the effects of reaction conditions, metal concentration and catalyst composition on the extent of deactivation and the effects of deactivation on catalyst strength are presented and discussed 相似文献
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A group contribution method for predicting the viscosity of binary and ternary liquid mixtures is proposed. Tests of the method against existing literature data show excellent agreement. Parameters for eight groups are presented. 相似文献
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A group contribution method for predicting the viscosity of binary and ternary liquid mixtures is proposed. Tests of the method against existing literature data show excellent agreement. Parameters for eight groups are presented. 相似文献
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Rajinder Pal 《Chemical Engineering Communications》1990,89(1):209-214
Mooney's viscosity equation, originally proposed for concentrated solids in liquid suspensions, has been tested for stable liquid in liquid emulsions. Nine different emulsion systems have been considered. In none of the cases considered, Mooney's equation is found to adequately describe the viscosity/concentration behavior. However, the modified form of the Mooney's equation ηr = exp[K1φ/(1—K2φ)]& is found to fit the data quite well. The K1 varies from 2.2 to 5.0 depending on the emulsion system; the K2 varies from 0.6 to 2.1. 相似文献
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In this paper we demonstrate several series of experiments for the measurement of viscosity of neat glycerol and its aqueous solutions using a tank-tube viscometer. Measuring viscosity of highly viscous liquids with the tank-tube viscometer is easier than other types of viscometers. This inexpensive viscometer continuously generates numerous reproducible viscosity data of highly viscous neat glycerol and its aqueous solutions under given experimental conditions such as a desired temperature and a desired concentration of water in aqueous glycerol solutions.
Fabricating the tank-tube viscometer is inexpensive, since this viscometer does not need sophisticated accessories such as a high-pressure liquid pump, a sensitive pressure sensor, and an accurate flow meter. The tank-tube viscometer consists of a large-diameter reservoir and a long, small-diameter, vertical tube.
The viscosity equation was developed under the following assumptions. Both the quasi steady state approach and the negligible friction loss due to a sudden contraction between the reservoir tank and the tube are valid. The kinetic energy of the emerging stream from the bottom end of the vertical tube of the tank-tube viscometer also is assumed to be negligible. Very viscous glycerol and its aqueous solutions were used to test the viscometer by comparing viscosity values from the viscometer with those from literatures.
The main objective of this study is to demonstrate effects of water as well as temperature on viscosity of aqueous glycerol solutions, applying experimental data of accumulated amounts of aqueous glycerol solutions at various drain durations to the newly-developed viscosity equation for the fabricated tank-tube viscometer. 相似文献
Fabricating the tank-tube viscometer is inexpensive, since this viscometer does not need sophisticated accessories such as a high-pressure liquid pump, a sensitive pressure sensor, and an accurate flow meter. The tank-tube viscometer consists of a large-diameter reservoir and a long, small-diameter, vertical tube.
The viscosity equation was developed under the following assumptions. Both the quasi steady state approach and the negligible friction loss due to a sudden contraction between the reservoir tank and the tube are valid. The kinetic energy of the emerging stream from the bottom end of the vertical tube of the tank-tube viscometer also is assumed to be negligible. Very viscous glycerol and its aqueous solutions were used to test the viscometer by comparing viscosity values from the viscometer with those from literatures.
The main objective of this study is to demonstrate effects of water as well as temperature on viscosity of aqueous glycerol solutions, applying experimental data of accumulated amounts of aqueous glycerol solutions at various drain durations to the newly-developed viscosity equation for the fabricated tank-tube viscometer. 相似文献
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Corresponding slates correlations have been developed for the viscosity and thermal conductivity of aqueous electrolyte solutions for a wide range of temperatures, pressures, and concentrations. For viscosity, the Vogel-Tamann-Fulcher equation has been generalized using the corresponding states theory, and extended to include pressure effects. Twenty six aqueous electrolyte solutions, including both monovalent and multivalent electrolytes, have been studied and a generalized correlation has been developed for viscosity, with four system dependent parameters. For thermal conductivity, a similar corresponding states based correlation has been developed. Twenty three aqueous electrolyte solutions were studied for thermal conductivity and a generalized equation was obtained that requires only two System dependent parameters. With both correlations, the maximum error is usually within 10% of the experimental values, with the average errors being much less. Additional systems can also be included in both correlations in a straightforward manner. 相似文献
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L.S. ASGElRSSON - Designer Engineer Icelandic Fisheries Laboratories Reykjavik Iceland. A.J. Ghajar 《Chemical Engineering Communications》1986,43(1):165-184
The objective of this work was to develop general, simple and accurate expressions to predict the peculiar behavior of thermal conductivity and viscosity in the near-critical region. Expressions were determined for (a) variation of thermal conductivity as a function of temperature and density or pressure for carbon dioxide, water, and ammonia, and for (b) variation of viscosity as a function of temperature and density or pressure for carbon dioxide, water, and nitrogen. The predicted results based on the developed expressions showed a very good agreement with the available thermal conductivity experimental data and an excellent agreement with the available viscosity experimental data 相似文献
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A constitutive diffusion theory for polymer solutions is proposed based on a thermomechanical mixture theory. A general expression for the diffusion flux in a binary polymer-solvent system is presented. It is shown that the current approach is capable of sorting out various complex diffusion phenomena. In particular, the dependence of the diffusion flux on a gradient of a generalized chemical potential emerges naturally by considering the limit of “weak equilibrium”. 相似文献
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运用化学反应工程理论分析影响减粘裂化过程诸因素。在塔径φ300mm塔高2700mm冷模装置中考察了横向筛板数、开孔率、孔径、空塔气速、空塔液速等因素对减粘反应塔液相反混的影响,为工业上流式减粘反应塔的设计提供理论和实验数据。 相似文献
12.
Binary and ternary experimental cloud‐point curves (CPCs) for systems formulated with a low molar mass synthesized divinylester (DVE) resin, styrene (St), and poly(methyl methacrylate) (PMMA) were determined. The CPCs results were analyzed with the Flory–Huggins (F‐H) thermodynamic model taking into account the polydispersity of the DVE and PMMA components, to calculate the different binary interaction parameters and their temperature dependences. The St‐DVE system is miscible in all the composition range and down to the crystallization temperature of the St; therefore, the interaction parameter expression reported for a higher molar mass DVE was adapted. The interaction parameters obtained were used to calculate the phase diagrams of the St‐PMMA and the DVE‐PMMA binary systems and that of the St‐DVE‐PMMA ternary system at three different temperatures. Quasiternary phase diagrams show liquid–liquid partial miscibility of the St‐PMMA and DVE‐PMMA pairs. At room temperature, the St‐DVE‐PMMA system is miscible at all compositions. Final morphologies of PMMA‐modified cured St‐DVE materials were generated by polymerization‐induced phase separation (PIPS) mechanism from initial homogeneous mixtures. SEM and TEM micrographs were obtained to analyze the generated final morphologies, which showed a direct correlation with the initial miscibility of the system. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4539–4549, 2006 相似文献
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A UNIFIED VISCOSITY MODEL FOR HYDROCARBON GASES AND LIQUIDS BASED ON TRANSPoSED PATEL-TEJA EQUATION OF STATE 下载免费PDF全文
A unified model for predicting high-pressure viscosities of both hydrocarbon gases and liquids was developed,which is based on the similarity between P-V-T and T-μ-P plots and Patel-Teja equation of state.The characteristic feature of this new model is its capability of describing the continuous variation of fluid viscosity throughciritical region.The pure component parameters are generalized into functions of reduced temperature,reducedpressure,acentric factor and molecular weight.The overall average absolute deviation of predicted viscositiesof 20 pure hydrocarbon fluids(a total of 1941 data points)is 8.7%. 相似文献
14.
Ke‐Jian Lian Chang‐Qing Chen Hui Liu Ning‐Xing Wang Hai‐Jiang Yu Zheng‐Hong Luo 《应用聚合物科学杂志》2011,120(1):156-164
Well‐defined poly(dimethylsiloxane)‐block‐poly(methyl methacrylate)‐block‐poly(2,2,3,3,4,4,4‐heptafluorobutyl methacrylate) (PDMS‐b‐PMMA‐b‐PHFBMA) triblock copolymers were synthesized via atom transfer radical polymerization (ATRP). Surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films was investigated. The microstructure of the block copolymers was investigated by transmission electron microscopy (TEM) and atomic force microscopy (AFM). Surface composition was studied by X‐ray photoelectron spectroscopy (XPS). The chemical composition at the surface was determined by the surface microphase separation in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films. The increase of the PHFBMA content could strengthen the microphase separation behavior in the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymer films and reduce their surface tension. Comparison between the PDMS‐b‐PMMA‐b‐PHFBMA triblock copolymers and the PDMS‐b‐PHFBMA diblock copolymers showed that the introduction of the PMMA segments promote the fluorine segregation onto the surface and decrease the fluorine content in the copolymers with low surface energy. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011 相似文献
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Porous poly(2‐hydroxyethyl methacrylate‐methyl methacrylate) particles crosslinked with ethylene glycol dimethacrylate were synthesized by free‐radical suspension copolymerization in an aqueous phase initiated by an oil‐soluble initiator, 2,2‐azobisisobutyronitrile. 1‐octanol was used as a pore forming agent (porogen). The porous structures, the particle morphology, and the swelling capacity of the resultant polymer in water at room temperature were studied at different crosslink densities and under various porogen concentrations. The analysis via Scanning Electronic Microscopy (SEM) indicated that permanent pores remained in the dried polymeric particles prepared in the presence of the porogen at certain crosslink densities. According to the studies via the SEM pictures and the pore size distributions, higher porogen concentration promotes the formation of more pores, and higher crosslink density results in narrower pore size distribution. The swelling capacity of the particles in water at room temperature decreases with an increase in the crosslink density, and the existence of the highly porous structures enhances the swelling capacity of the porous particles of poly(2‐hydroxyethyl methacrylate‐methyl methacrylate). © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 707–715, 2007 相似文献
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Graft copolymerization of methyl methacrylate monomer onto ultra high molecular weight polyethylene (UHMWPE) and acid‐etched UHMWPE was conducted using preirradiation method in air in the presence of a Mohr salt and sulfuric acid to improve adhesion to the bone cement. The grafted samples were characterized by Fourier transform infrared (FTIR) spectroscopy, gravimetric method, goniometry, and interfacial bonding strength measurements. The FTIR results showed the presence of ether, carbonyl, and hydroxyl groups for grafted films. The gravimetric results showed that the chromic acid etching and graft copolymerization had a synergetic effect so, the irradiated, then chromic acid etched at room temperature and grafted sample (Rad etch25) had the highest grafting degree. The interfacial bonding strength between UHMWPE and poly methyl methacrylate bone cement was considerably improved by graft copolymerization and chromic acid etching. The surface morphology was studied by scanning electron microscopy. The substitution of polar groups into the backbone of UHMWPE by chromic acid etching and graft copolymerization changed its contact angles with water and methylene iodide and increased its surface energy, as evidenced by contact angle measurements. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 相似文献
18.
Arie Ram 《Chemical Engineering Communications》1984,30(3):285-289
An overview is presented of high shear viscometry, namely the viscous behavior of viscoelastic fluids in the second Newtonian region. Important theories are discussed and the contributions of Edward Merrill in the area are presented. 相似文献
19.
Jui‐Ming Yeh Chang‐Jian Weng Kuan‐Yeh Huang Hsi‐Ya Huang Yuan‐Hsiang Yu Chung‐Hung Yin 《应用聚合物科学杂志》2004,94(1):400-405
A series of sol‐gel derived organic–inorganic hybrid materials consisting of organic poly(methyl methacrylate) (PMMA) and inorganic titania (TiO2) were successfully synthesized by using 2‐hydroxyethyl methacrylate (HEMA) as coupling agent. In this work, HEMA is first copolymerized with methyl methacrylate monomer at specific feeding ratios by using benzoyl peroxide (BPO) as initiator. Subsequently, the as‐prepared copolymer (i.e., sol‐gel precursor) is then cohydrolyzed with various contents of titanium butoxide to afford chemical bondings to the forming titania networks to give a series of hybrid materials. Transparent organic–inorganic hybrid materials with different contents of titania are always achieved. Effects of the material composition on the thermal stability, optical properties, and morphology of neat copolymer and a series of hybrid materials, in the form of both coating and free‐standing film, are also studied by differential scanning calorimetry, thermogravimetric analysis, UV–Vis transmission spectra, refractometer, and atomic force microscopy, respectively. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 400–405, 2004 相似文献
20.
The propagator of the unsteady Stokes equation is shown to be dominated by the solution of a purely diffusive equation, whose dispersion coefficient is the viscosity. Pressure plays an indirect role only, by creating instantaneously a steady velocity field which decays slowly in space. Viscosity appears to measure the temporal growth of the second moment of the unsteady Stokes propagator. 相似文献