Phase behavior of (CO2+H2) and (CO2+N2) at temperatures between (218.15 and 303.15)K at pressures up to 15MPa

Abstract

Vapor-liquid equilibrium data are reported for the binary systems (CO2 + H2) and (CO2 + N2) at temperatures between (218.15 and 303.15) K at pressures ranging from the vapor pressure of CO2 to approximately 15 MPa. These data were measured in a new analytical apparatus which is described in detail. The results are supported by a rigorous assessment of uncertainties and careful validation measurements. The new data help to resolve discrepancies between previous studies, especially for the (CO2 + H2) system. Experimental measurements of the three-phase solid-liquid-vapor locus are also reported for both binary systems.The vapor-liquid equilibrium data are modelled with the Peng-Robinson (PR) equation of state with two binary interaction parameters: one, a linear function of inverse temperature, applied to the unlike term in the PR attractive-energy parameter; and the other, taken to be constant, applied to the unlike term in the PR co-volume parameter. This model is able to fit the experimental data in a satisfactory way except in the critical region. We also report alternative binary parameter sets optimized for improved performance at either temperatures below 243 K or temperatures above 273 K. A simple predictive model for the three-phase locus is also presented and compared with the experimental data.

Vapor–liquid equilibrium data for the carbon dioxide and nitrogen (CO2 + N2) system at the temperatures 223, 270, 298 and 303 K and pressures up to 18 MPa

“…At 303.16 K, our data and the recent data by Fandiño et al [30] seemed to be in good agreement up to their liquid and vapor points at 7.42 MPa. Above this pressure, their bubble point at 7.5 MPa was lower in CO 2 content than the bubble point line predicted by our data.…”

“…In addition, their data contained a bubble point at 7.5717 MPa, which was 0.014 MPa higher than the maximum pressure of our bubble and dew points. Our data at the highest pressures suggested close proximity to the critical point, lower than what was suggested by the bubble point of Fandiño et al [30]. At 303.16 K, some instability was seen in the composition of our vapor data.…”

“…This was probably due to a small leakage in the nitrogen filled bellows into the VLE cell, which were later detected. However, this leakage did not explain the apparent difference in critical pressure between our measurements and those of Fandiño et al [30]. For comparison, in our apparatus, the transition between the two-phase region into the supercritical region could visually be observed and accurately determined within approximately 0.02 MPa for the VLE measurements at 298.17 K.…”

The phase equilibrium and density studies of the ternary mixtures of CO 2 + Ar + N 2 and CO 2 + Ar + H 2 , systems relevance to CCS technology

“…Recently, much attention has been given to studies of the thermodynamic properties, such as vapour-liquid equilibrium (VLE) and density of CO2 mixtures with impurities. A number of research groups have studied some of these key binaries, such as CO2/N2 (Fandino et al, 2015;Mantovani et al, 2012;Tenorio et al, 2015;Westman et al, 2016b), CO2/Ar (Coquelet et al, 2008;Köpke and Eggers, 2007;Mantovani et al, 2012;Yang et al, 2015a), CO2/H2 (Cipollina et al, 2007;Fandino et al, 2015;Sanchez-Vicente et al, 2013;Tenorio et al, 2015), CO2/O2 (Mantovani et al, 2012;Westman et al, 2016a), CO2/SO2 (Coquelet et al, 2014;Köpke and Eggers, 2007), CO2/CO (Cipollina et al, 2007), CO2/H2S (Chapoy et al, 2013a) and CO2/H2O (Hou et al, 2013;Valtz et al, 2004), which either focused on the binaries with an insufficient amount of data under the conditions relevant to CCS or aimed at reducing experimental uncertainties. A comprehensive data survey of the available thermodynamic properties of binary systems with CO2 can be found in the monograph by Kunz et al (2007) and in the recent reviews by Munkejord et al (2016) and Li.…”

Molecular simulation of the thermophysical properties and phase behaviour of impure CO2 relevant to CCS

“…There is an extensive range of data for CO 2 +N 2 mixtures, several data sets for CO 2 +O 2 and CO 2 +Ar mixtures and some very recently published data 5,8 on CO 2 +H 2 .…”