Vapor-Liquid Equilibria of Formaldehyde-Methanol-Water

Green, Stanley J.; Vener, Raymond E.

doi:10.1021/ie50541a037

Cited by 34 publications

(21 citation statements)

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“…Aqueous mixtures comprising nonassociating components such as methane and carbon diox- Figure 24. Isobaric temperature-mole fraction representation of the vapour-liquid equilibria of the water + methanol binary mixture at P = 1 atm: the symbols represent the experimental data [205][206][207][208][209][210], and the curves the description obtained using the SAFT-VR Mie EOS with our novel treatment of the association contribution based on the generic Mie kernel, Equation (30).…”

Section: Binary Aqueous Mixtures Of Methanol Methane Carbon Dioxidementioning

confidence: 99%

“…The model adopted for water is that from Table 3 (with the generic Mie association contribution), and that for methanol is specified in Table 5. In this case, only a small deviation from the geometric-mean combining rule for the unlike dispersive energy is required, corresponding to a binary parameter of k ij = 0.04 in Equation (47), to provide good agreement with the experimental data [205][206][207][208][209][210] for the vapour-liquid envelope; the 'standard' combining rules defined in Section 6.2 are employed for all other unlike interaction parameters.…”

Section: Binary Aqueous Mixtures Of Methanol Methane Carbon Dioxidementioning

confidence: 99%

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The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

et al. 2015

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(2015) The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids, Molecular Physics, 113:9-10, 948-984, DOI: 10.1080/00268976.2015 An accurate representation of molecular association is a vital ingredient of advanced equations of state (EOSs), providing a description of thermodynamic properties of complex fluids where hydrogen bonding plays an important role. The combination of the first-order thermodynamic perturbation theory (TPT1) of Wertheim for associating systems with an accurate description of the structural and thermodynamic properties of the monomer fluid forms the basis of the statistical associating fluid theory (SAFT) family of EOSs. The contribution of association to the free energy in SAFT and related EOSs is very sensitive to the nature of intermolecular potential used to describe the monomers and, crucially, to the accuracy of the representation of the thermodynamic and structural properties. Here we develop an accurate description of the association contribution for use within the recently developed SAFT-VR Mie framework for chain molecules formed from segments interacting through a Mie potential [T. Lafitte, A. Apostolakou, C. Avendaño, A, Galindo, C. S. Adjiman, E. A. Müller, and G. Jackson, J. Chem. Phys. 139, 154504 (2013)]. As the Mie interaction represents a soft-core potential model, a method similar to that adopted for the Lennard-Jones potential [E. A. Müller and K. E. Gubbins, Ind. Eng. Chem. Res. 34, 3662 (1995)] is employed to describe the association contribution to the Helmholtz free energy. The radial distribution function (RDF) of the Mie fluid (which is required for the evaluation of the integral at the heart of the association term) is determined for a broad range of thermodynamic conditions (temperatures and densities) using the reference hyper-netted chain (RHNC) integral-equation theory. The numerical data for the association kernel of Mie fluids with different association geometries are then correlated for a range of thermodynamic states to obtain a general expression for the association contribution which can be applied for varying values of the Mie repulsive exponent. The resulting SAFT-VR Mie EOS allows for a much improved description of the vapour-liquid equilibria and single-phase properties of associating fluids such as water, methanol, ammonia, hydrogen sulphide, and their mixtures. A comparison is also made between the theoretical predictions of the degree of association for water and the extent of hydrogen bonding obtained from molecular simulations of the SPC/E and TIP4P/2005 atomistic models.

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Section: Binary Aqueous Mixtures Of Methanol Methane Carbon Dioxidementioning

confidence: 99%

Section: Binary Aqueous Mixtures Of Methanol Methane Carbon Dioxidementioning

confidence: 99%

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

et al. 2015

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“…Apart from being soluble in most organic solvents, in water it is strongly solvated or in the form of low molar mass polymers. Therefore, its vapour pressure is very low over aqueous solutions and it forms azeotropes with water [2]. This makes its separation from water difficult.…”

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confidence: 99%

Catalytic dehydrogenation of methanol to water‐free formaldehyde

Zaza

Renken

1994

Chem Eng & Technol

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Catalytic dehydrogenation of methanol is a promising process of producing water-free formaldehyde. The present paper reviews research in this field. As effective catalysts mainly transition metal compounds as well as oxides and salts containing sodium have been reported. Several catalysts exhibit high activity and high selectivity, for formaldehyde at low conversions while further efforts have to be made to improve catalyst stability and selectivity at high conversions. Catalytic dehydrogenation of methanol to formaldehyde is compared with methanol oxidation. Current Production and Uses of FormaldehydeSince its initial discovery in 1859 by Butlerov, formaldehyde has become one of the most important chemicals in industry. In 1985 its world production amounted to about five million tons [l]. At room temperature, formaldehyde is a colourless gas with a pungent odour. It is unstable and polymerizes easily to form polyoxymethylenes both in the gas phase and in solutions. One of its properties of practical importance is the condensation reaction with compounds containing active hydrogen to produce water and compounds with -CH20H or -CH2 groups. Apart from being soluble in most organic solvents, in water it is strongly solvated or in the form of low molar mass polymers. Therefore, its vapour pressure is very low over aqueous solutions and it forms azeotropes with water [2]. This makes its separation from water difficult.Although oxidation of hydrocarbons is used to obtain formaldehyde, more than 90% of the world's formaldehyde production is at present achieved through catalytic oxidation of methanol [3]. Two processes, namely the silver catalyst process and the formox process, are commonly employed [3 -51. In the former, a methanol-rich methanolair-steam mixture (36 -45% methanol) is passed through the catalyst bed at 870 -970 K. The following reactions occur:CH30H + CH20 + H2 , AH900 = + 92 kJ/mol , (1) The conversion may either be complete or, alternatively, incomplete with recycling of methanol. The selectivity is about go%, with carbon oxides, methyl formate, methane and formic acid as by-products. The formox process differs from the silver catalyst process in the nature of the catalyst (iron-molybdenum oxides), methanol concentration (5 -10% methanol) and oxidation temperature (570 -670 K). Only reactions 2 and 3 take place under these conditions. In both processes, aqueous solutions are obtained and marketed as final products. Formaldehyde is also available commercially in its solid form, i.e., paraformaldehyde, which consists of polyoxymethylenes and is easily decomposed to formaldehyde. It is produced by distilling formaldehyde solutions under vacuum.Formaldehyde finds a wide application in industry. Although it is used to make other chemicals, most of its production is used to synthesize aminophenol and polyacetal resins through condensation reactions. Water in the aqueous solutions often interferes with these processes. When a small quantity of water is tolerable, paraformaldehyde can be used instead. Occasion...

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“…Vapor-liquid-equilibrium data (8,27) for several methanolic formaldehyde solutions are given in Table 2. The flash point varies with composition, decreasing from 83 to 60 C as the formaldehyde and methanol concentrations increase (17,18).…”

Section: Physical Propertiesmentioning

confidence: 99%

Formaldehyde

Gerberich

Seaman

Staff³

2013

Kirk-Othmer Encyclopedia of Chemical Technology

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Formaldehyde is the first of the series of aliphatic aldehydes. It was discovered by Butlerov in 1859 and has been manufactured since the beginning of the twentieth century. At ordinary temperatures formaldehyde is a colorless gas with a pungent odor. Because of its relatively low cost, high purity, and variety of chemical reactions, formaldehyde has become on of the world's most important industrial and research chemicals. Historically, formaldehyde has been and continues to be manufactured from methanol via the silver catalyst process or the the metal oxide catalyst process. New processes are under development. Sources of human exposure to formaldehyde are many, ie, engine exhaust, tobacco smoke, natural gas, waste incineration, etc. It is known to be a human carcinogen. Formaldehyde is a basic chemical building block for the production of a wide range of chemicals. Its biggest use is in the production of industrial resins; urea‐formaldhyde; phenol formaldehyde; and melamine formaldehyde. It is also used, eg, in the production of 1,4‐butanediol, polyols, chelating agents, slow release fertilizers, hexamethylenetetramine, and paraformaldehyde.

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Vapor-Liquid Equilibria of Formaldehyde-Methanol-Water

Cited by 34 publications

References 6 publications

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

The A in SAFT: developing the contribution of association to the Helmholtz free energy within a Wertheim TPT1 treatment of generic Mie fluids

Catalytic dehydrogenation of methanol to water‐free formaldehyde

Formaldehyde

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