Acentric Factor. A Valuable Correlating Parameter for the Properties of Hydrocarbons

Passut, Charles A.; Danner, Ronald P.

doi:10.1021/i260047a026

Cited by 49 publications

(15 citation statements)

References 3 publications

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“…The critical pressure predicted by this method for n-paraffins is in very good agreement with experimental data reported in the literature (Reid et al, 1977;Ambrose and Tsonopoulos, 1995;Passut and Danner, 1973;Poling et al, 2001;Nikitin et al, 1997;Gao et al, 1999Gao et al, , 2001) as shown in Figure B.2. Comparison of Joback's method with other methods for n-paraffin critical pressure is also shown in this figure.…”

Section: Critical Pressuresupporting

confidence: 89%

Kinetics of Slurry Phase Fischer-Tropsch Systhesis

Bukur¹,

Froment²,

Olewski³

2005

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Also, we have successfully applied the Levenberg-Marquardt method (Marquardt, 1963) to estimate parameters of a kinetic model proposed earlier by Lox and Froment (1993b) for FTS on an iron catalyst. This kinetic model is well suited for initial studies where the main goal is to learn techniques for parameter estimation and statistical analysis of estimated values of model parameters. It predicts that the chain growth parameter (α) and olefin to paraffin ratio are independent of carbon number, whereas our experimental data show that they vary with the carbon number. Predicted molar flow rates of inorganic species, n-paraffins and total olefins were generally not in good agreement with the corresponding experimental values. In the future we'll use kinetic models based on non-constant value of α.

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Section: Critical Pressuresupporting

confidence: 89%

Kinetics of Slurry Phase Fischer-Tropsch Systhesis

Bukur¹,

Froment²,

Olewski³

2005

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“…According to this method the critical pressure is calculated as: Average error for compounds with 3 or more carbon atoms is less then 5% (Poling et al, 2001). The critical pressure predicted by this method for n-paraffins is in very good agreement with experimental data reported in the literature (Reid et al, 1977;Ambrose and Tsonopoulos, 1995;Passut and Danner, 1973;Poling et al, 2001;Nikitin et al, 1997;Gao et al, 1999Gao et al, , 2001 as shown in Figure B.2. Comparison of Joback's method with other methods for n-paraffin critical pressure is also shown in this figure.…”

Section: Critical Pressuresupporting

confidence: 88%

Kinetics of Slurry Phase Fischer-Tropsch Synthesis

Bukur¹,

Froment²,

Nowicki³

et al. 2006

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The overall objective of this project is to develop a comprehensive kinetic model for slurry-phase Fischer-Tropsch synthesis (FTS) employing iron-based catalysts. This model will be validated with experimental data obtained in a stirred-tank slurry reactor (STSR) over a wide range of process conditions. Three STSR tests of the Ruhrchemie LP 33/81 catalyst were conducted to collect data on catalyst activity and selectivity under 25 different sets of process conditions. The observed decrease in 1-olefin content and increase in 2-olefin and n-paraffin contents with the increase in conversion are consistent with a concept that 1-olefins participate in secondary reactions (e.g. 1-olefin hydrogenation, isomerization and readsorption), whereas 2-olefins and n-paraffins are formed in these reactions. Carbon number product distribution showed an increase in chain growth probability with increase in chain length.Vapor-liquid equilibrium calculations were made to check validity of the assumption that the gas and liquid phases are in equilibrium during FTS in the STSR. Calculated vapor phase compositions were in excellent agreement with experimental values from the STSR under reaction conditions. Discrepancies between the calculated and experimental values for the liquidphase composition (for some of the experimental data) are ascribed to experimental errors in the amount of wax collected from the reactor, and the relative amounts of hydrocarbon wax and Durasyn 164 oil (start-up fluid) in the liquid samples.Kinetic parameters of four kinetic models (Lox and Froment, 1993b;Yang et al., 2003; Beenackers, 1998, 1999; and an extended kinetic model of Van der Laan and Beenackers) were estimated from experimental data in the STSR tests. Two of these kinetic models (Lox and Froment, 1993b;Yang et al., 2003) can predict a complete product distribution (inorganic species and hydrocarbons), whereas the kinetic model of Beenackers (1998, 1999) can be used only to fit product distribution of total olefins and nparaffins. The kinetic model of Van der Laan and Beenackers was extended to account separately for formation of 1-and 2-olefins, as well as n-paraffins.A simplified form of the kinetic model of Lox and Froment (1993b) has only five parameters at isothermal conditions. Because of its relative simplicity, this model is well suited for initial studies where the main goal is to learn techniques for parameter estimation and statistical analysis of estimated values of model parameters. The same techniques and computer codes were used in the analysis of other kinetic models. The Levenberg-Marquardt (LM) method was employed for minimization of the objective function and kinetic parameter estimation. Predicted reaction rates of inorganic and hydrocarbon species were not in good agreement with experimental data.All reaction rate constants and activation energies (24 parameters) of the Yang et al. (2003) model were found to be positive, but the corresponding 95% confidence intervals were large. Agreement between predicted and ex...

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“…A similar procedure using a vapor pressure equation and the boiling point was used by Lee and Kesler in their calculations. The values of the acentric factors calculated above are not very different from conventional values reported by Passut and Danner (1973). …”

Section: Applications To Lngcontrasting

confidence: 46%

A Corresponding States equation for saturated liquid densities. I. Applications to LNG

Teja

1980

AIChE Journal

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Presented here is a Corresponding States Method for predicting saturated liquid densities of both pure components and mixtures The method is based on the known properties of two reference fluids and requires the critical properties and the acentric factor of the pure component(s) as input parameters. The method is tested for predicting the orthobaric densities of LNG mixtures using methane and n-butane as the reference fluids. Very accurate predictions (well within the accuracy of the experimental data) are obtained for such mixtures using, at most, only one adjustable coefficient to characterize each binary system. The method is extremely simple to use and is suitable for design applications.An extended form of Pitzer's three-parameter principle is proposed here, using two (nonspherical) reference fluids. The method is capable ofwidespread application and yet, can lead to very accurate predictions of the properties of a limited class substances with a suitable choice of references. THE PROPOSED METHODThe principle which is extended in this study was originally proposed by Pitzer et al. (1955) who showed that the compressibility factor (expressed as a function of reduced temperature and reduced pressure) can be written as a linear function of the acentric factor aswhere 2"' is the compressibility factor of a simple fluid with zero acentric factor at the same reduced conditions and 2"' is a complicated deviation function. Other thermodynamic properties can b e written in a similar way. ooO1 1541 80 36b6 0341-$00 75 The American lnatitutc of Cllemtcal Engineers, 1980 sponding states principle, based on two reference fluids chosen so that their properties are close to the key components of interest. The method gives extremely accurate predictions of the saturated liquid densities of LNG mixtures (Teja 1980), when the critical properties and acentric factors of the cornponents are known.When the critical properties and acentric factors have to be estimated, as in the case of crude oils in COz-crude oil mix-

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Acentric Factor. A Valuable Correlating Parameter for the Properties of Hydrocarbons

Cited by 49 publications

References 3 publications

Kinetics of Slurry Phase Fischer-Tropsch Systhesis

Kinetics of Slurry Phase Fischer-Tropsch Systhesis

Kinetics of Slurry Phase Fischer-Tropsch Synthesis

A Corresponding States equation for saturated liquid densities. I. Applications to LNG

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