Critical Evaluation of Ethene Solubility in Cyclohexane and Various Aromatic Hydrocarbons for Pressures greater than 0.2 MPa (2 atm)

Ten groups of researchers^1-10 have measured solubility for ethene in cyclohexane and in various aromatic hydrocarbons at elevated pressures. Solubility were measured by two or more groups for benzene, toluene and xylenes but in general there are relatively few data available so that extensive evaluations are not possible. One group³ has studied two-component solvent systems.

Few sets of data included both the liquid and gas phase compositions. In this evaluation we have, where possible, checked if the available data give a linear relationship for log x versus log P, which is indicative but not conclusive of consistent data. Furthermore, where possible we have compared extrapolated values at a partial pressure of 0.1013 MPa with values determined at or near 0.1013 MPa pressure. Correlating equations have been included where possible.

Cyclohexane; C₆H₁₂; [110-82-7]

This system has been investigated¹ at six temperatures from 303 K to 423 K at pressures between 1.7 MPa and 9.0 MPa. Linear plots were obtained at all temperatures when log x was plotted against log P. There are no gross inconsistencies in the data. Considerable uncertainty is involved in the long extrapolation of the data to 101.3 kPa. but the values obtained appear about 10% greater than the values obtained from the work of Krauss and Gestrich¹¹ (Please see low pressure Critical Evaluation). The values of Zhuze et al.¹ are therefore classified as tentative.

Benzene; C₆H₆; [71-43-2]

Ethene solubility in benzene have been reported by five groups of research workers^2,4,8-10 for total pressures from 0.28 MPa to 19.3 MPa and for temperatures ranging from 293 K to 423 K. The results of Paratella and Sagramora⁸ are rejected. Their solubility are considerably lower than those of any other group and extrapolate to 101.3 kPa to give values considerably smaller than the tentative low-pressure values. The data of Hiraoka¹⁰ are difficult to evaluate; the lower temperature solubility are broadly consistent with Henry's law constants determined from low-pressure measurements but there are no low-pressure results at the higher temperatures for comparison. The data of Ellis et al.⁹ at 348.15 K are broadly consistent with the data of Kozorezov et al.⁴ at the same temperature. The data of Kozorezov et al.⁴ appear to have a reasonable temperature dependency and together with the limited data of Ellis et al. are classified as tentative. The data of Konobeev and Lyapin² are consistent with the data of Kozorezov et al.⁴ and are also classified as tentative.

Methylbenzene; C₇H₈; [108-88-3]
This system has been studied by four groups of workers^{2, 5-7} for temperatures ranging from 228 K to 473 K and total pressures from 0.1 to 6 MPa. It is difficult to evaluate the data because of the different temperature and pressure ranges involved. Frank⁷ measured the solubility of ethene in toluene at four temperatures between 273 K and 323 K up to pressures of 0.4 MPa. The values of the solubility extrapolated to 0.1013 MPa are several percent lower than the values measured at or near 0.1013 MPa. The Henry's law constants obtained from the graphs given by Tyvina et al.⁵ can be used to calculate the mole fraction solubility of ethane in toluene at a partial pressure of 0.1013 MPa. The. values are in fair agreement with the values measured at or near 0.1013. MPa considering the problem of obtaining the solubility from the graphs. The results of Knonbeev and Lyapin² are consistent with the values of Tyvina et al.⁵. The data of Shenderei et al.⁶ are the only low temperature data available at elevated pressures. The values extrapolated to 0.1013 MPa and 238.15 K and 248.15 K are consistent with the low-pressure data of Leites and Ivanovskii¹². Please see low pressure Critical Evaluation: None of the sets of data can be recommended but the data of Shenderei et al.⁶, Tyvina et alI.⁵ and Konobeev and Lyapin² are classified as tentative for the temperature and pressure range covered by the respective data. Please see Table 1.

Table 1. Comparison of Extrapolated High Pressure Solubility with Low Pressure Results for the System Ethene - Methylbenzene


T/K = 273.15
Av. Extrapolated solubility^a 0.0204 (Ref. 7)
Solubility measured at low pressure^a 0.0207
% Deviation -1.4

T/K = 293.15
Av. Extrapolated solubility^a 0.0139 (Ref. 5)
Solubility measured at low pressure^a 0.0152
% Deviation -8.5

Av. Extrapolated solubility^a 0.0146)
-% Deviation -3.9

T/K = 308.15
Av. Extrapolated solubility^a 0.0114 (Ref. 7)
Solubility measured at low pressure^a 0.0.0124
% Deviation -8.1

T/K = 313.15
Av. Extrapolated solubility^a 0.0108 (Ref. 5)
Solubility measured at low pressure^a 0.0116
% Deviation -6.9

^a at a partial pressure of 0.1013 MPa

1,2-Dimethylbenzene; C₈H₁₀; [106-42-3]
1,3-Dimethylbenzene; C₈H₁₀; [108-38-3]
1,4-Dimethylbenzene; C₈H₁₀; [95-47-6]

Ethene solubility in a mixture of xylenes were reported by Konobeev and Lyapin² at pressures from 0.28 MPa to 3.21 MPa and temperatures from 293 K to 333 K. Nakamura et al.³ reported ethene solubility in each xylene isomer at six temperatures ranging from 213 K to 303 K and total pressures up to 1.28 MPa. Although the authors did not provide ethene partial pressures, they gave average Henry's constants for each operating temperature. Assuming a direct inverse relationship between Henry's law constant and the mole fraction solubility at an ethene partial pressure of 101.3 kPa, the latter was calculated and plotted against 1/T. A linear relationship was obtained in all cases and this shows some degree of consistency of the data. The equation of the line of best fit was determined for each of the isomers. The equations of the lines and the corresponding correlation coefficients are:

1,2-dimethylbenzene
log x = -3.74 + 569.3/(_T/K) coeff = 0.9992

(1)

1,3-dimethylbenzene
log x -3.85 + 591.2/(T/K) coeff. = 0.9998

(2)

1, 4-dimethylbenzene
log x = -3.90 + 599.7/(T/K)

(3)

It is not meaningful to give a correlation coefficient for the 1,4-dimethylbenzene solubility since half of the values were obtained by extrapolation of data for the binary solvent (1,4-dimethylbenzene + ethylbenzene) results.

In Table 2 the extrapolated high-pressure solubility data of Nakamura et al.³ have been compared with the low-pressure measurements of Krauss and Gestrich¹¹ for 1,3-dimethylbenzene. The average deviation between the two sets of data was 3.9%. At 293.15 K the data of Konobeev and Lyapin² for the dimethylbenzene mixture are consistent with those of Nakamura et al.³ at the same temperature. Both are classified as tentative.

Table 2. Comparison of Extrapolated High Pressure Solubility with Low Pressure for the System Ethene - 1,3-Dimethylbenzene

T/K=293.15
Av. extrapolated solubility_a 0.0151
Solubility measured at low pressure^a 0.0159
% deviation -5.0

T/K=273.15

Av. extrapolated solubility_a 0.0205
Solubility measured at low pressure^a 0.0214
% deviation -4.0

T/K=252.65
Av. extrapolated solubility_a 0.0313
Solubility measured at low pressure^a 0.0304
% deviation +2.7
^a at a partial pressure of 0.1013 MPa

Ethylbenzene; C₈H₁₀; [100-41-4]

Nakamura et al.³ reported solubility data for ethene in ethyl-benzene at temperatures ranging from 196 K to 293 K and Kororezov et al.⁴ measured ethene solubility at similar pressures but for temperatures in the range 323 K to 423 K. Both workers gave Henry's constants and using these constants values of solubility at a partial pressure of 101.3 kPa were calculated. The data of the two groups of workers gave colinear points on a plot of log _x versus l/T and are thus considered to be consistent with each other. The equation of the best-fit line is:

log x = -3.628 + 534.5/(T/K)

(4)

Since this equation has a correlation coefficient of 0.9983 it provides a suitable estimate of the solubility of ethene in ethylbenzene over the temperature range 196 K to 423 K

The data of Nakamura et al.³ and Kororezov et al.⁴ are both classified as tentative.

Diethylbenzene; C₁₀H₁₄ [25340-17-4]

Ethene solubility in diethylbenzene were reported by Kozorezov et al.⁴ for total pressures from 0.25 MPa to 1.52 MPa at temperatures ranging from 323 K to 423 K. The authors gave Henry's constants and the mole fraction solubility at partial pressures of 101.3 kPa were calculated (assuming a direct inverse relationship) and were plotted against l/T.

A linear plot was obtained; therefore, the data of Kozorezov et al.⁴ are classified as tentative.

Benzene, 1,4-dimethyl-, (p-xylene); C₈H₁₀; (106-42-3] and Ethylbenzene, C₈H₁₀; [100-41-4] solvent mixtures
Benzene, 1, 3-dimethyl-, (m-xylene); C₈H₁₀; [108-38-3] and Ethylbenzene C₈H₁₀; [100-41-4] solvent mixtures
Benzene, 1,2-dimethyl-, (o-xylene); C₈H₁₀; [95-47-6] and Ethylbenzene; C₈H₁₀; [100-41-4] solvent mixtures

Nakamura et al.³ measured the solubility of ethene in two component solvent mixtures containing ethylbenzene and each of the three-xylene isomers at temperatures in the range of 213.15 K to 273.15 K. The working pressures were in the range of 192.5 kPa to 983 kPa. Based on the evaluation of the data in the pure solvents by these authors, these data also are classified as tentative.