Equilibrio de fases

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J. of Supercritical Fluids 31 (2004) 111–121

Phase equilibrium data on binary and ternary mixtures of methyl palmitate, hydrogen and propane
L.J. Rovetto a , S.B. Bottini a,∗ , C.J. Peters b
b

PLAPIQUI, Universidad Nacional del Sur-CONICET, CC 717, 8000 Bah´a Blanca, Argentina ı Laboratory of Physical Chemistry and Molecular Thermodynamics, Delft University of Technology, Julianalaan 136,2628 BL Delft, The Netherlands Received 26 August 2003; accepted 27 October 2003

a

Abstract The hydrogenolysis of fatty acid methyl esters (FAME) to obtain fatty alcohols, is a catalytic, multiphase reaction. Reaction rates can be greatly increased by using a supercritical solvent to bring the reactive mixture into a single homogeneous phase. Knowledge of the corresponding phase equilibriais a prerequisite in order to find the homogeneous region and to determine the most favorable conditions for the hydrogenation process. This paper reports experimental phase equilibrium data on binary and ternary mixtures of methyl palmitate, hydrogen and propane. A temperature region between 360 and 450 K, and pressures up to 15 MPa were covered. © 2003 Elsevier B.V. All rights reserved.Keywords: Supercritical hydrogenolysis; Phase equilibria; Methyl palmitate; Hydrogen; Propane

1. Introduction Fatty alcohols (FOH) are normally produced by hydrogenolysis of fatty acid methyl esters (FAME), in a catalytic multiphase reaction. The yield of FOH and the reaction rate depend of the hydrogen pressure in the reactor [1]. On an industrial scale, the high-pressure catalytic hydrogenation iscarried out in a trickle-bed or a slurry-phase reactor. A copper-based catalyst is commonly used and temperatures ranging from 523 up to 573 K and pressures between 20 and 30 MPa are the normal operating conditions [2]. A
∗ Corresponding author. Tel.: +54-291-486-1700; fax: +54-291-486-1600. E-mail address: sbottini@plapiqui.edu.ar (S.B. Bottini).

large excess of hydrogen (20–100 mol H2 per molof ester, according to Buchold [3] and Kreutzer [4]) and high pressures are required to overcome the problem of low hydrogen (H2 ) solubility in the reaction mixture. This low solubility introduces mass transport resistance in the liquid phase and limits the availability of H2 at the catalyst surface; i.e., the reaction rate is diffusion controlled. The low concentration of H2 at the catalystsurface does not only have the consequence of producing relatively low reaction rates, but it also favors partial isomerization of the cis double-bonds into the trans configuration [5,6]. A way to increase the concentration of H2 at the catalyst surface is to introduce a supercritical solvent into the reaction mixture. The role of the supercritical fluid is to bring both, the gas and the

0896-8446/$– see front matter © 2003 Elsevier B.V. All rights reserved. doi:10.1016/j.supflu.2003.10.003

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L.J. Rovetto et al. / J. of Supercritical Fluids 31 (2004) 111–121

Table 1 Vapor–liquid isopleths of the system methyl palmitate (1)–hydrogen (2) T (K) x2 = 0.0495 L +V → L 450.26 445.32 440.36 435.44 430.51 425.54 420.61 413.19 405.73 398.31 390.92 383.44 376.06 368.59 361.23 p (MPa) T (K) x2= 0.0794 L +V → L 449.84 445.13 439.91 435.37 430.23 425.37 420.20 412.96 406.05 398.40 390.84 383.44 376.08 368.72 361.36 p (MPa) T (K) x2 = 0.1028 L +V → L 450.33 445.40 440.43 435.47 430.54 425.56 420.60 413.19 405.76 398.33 390.88 383.44 376.02 368.69 361.27 p (MPa) T (K) x2 = 0.1284 L +V → L 450.08 444.73 440.33 435.29 430.40 425.44 420.45 412.95 405.86 398.24 390.89 383.42 376.12 368.71363.77 p (MPa)

3.506 3.576 3.636 3.706 3.781 3.851 3.926 4.041 4.166 4.301 4.441 4.596 4.751 4.911 5.086

5.830 5.935 6.035 6.155 6.265 6.380 6.515 6.705 6.905 7.130 7.360 7.595 7.850 8.140 8.430

7.773 7.899 8.044 8.194 8.349 8.514 8.679 8.934 9.229 9.524 9.839 10.164 10.514 10.884 11.274

10.010 10.190 10.365 10.540 10.740 10.920 11.130 11.456 11.801 12.181 12.581 12.991 13.431 13.916...
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