Phase equilibria of clathrate hydrates of carbon disulfide þ nitrogen or carbon dioxide þ water system Amir H. Mohammadi a,b,n , Dominique Richon b,c a MINES ParisTech, CEP/TEP—Centre E ´ nerge´tique et Proce´de´s, 35 Rue Saint Honore´, 77305 Fontainebleau, France b Thermodynamics Research Unit, School of Chemical Engineering, University of KwaZulu-Natal, Howard College Campus, King George V Avenue, Durban 4041, South Africa c Department of Biotechnology and Chemical Technology, School of Science and Technology, Aalto University, P.O. Box 16100, 00076 Aalto, Finland HIGHLIGHTS c Dissociation pressures for hydrates of the CS 2 þN 2 /CO 2 þH 2 O system are reported. c An isochoric pressure search method was used to perform the measurements. c The obtained dissociation data are compared with selected data from the literature. c It is shown that CS 2 has promotion effect on nitrogen clathrate hydrates. c Negligible effect of CS 2 has been found on carbon dioxide hydrates. article info Article history: Received 17 August 2012 Received in revised form 26 December 2012 Accepted 3 January 2013 Available online 10 January 2013 Keywords: Gas hydrate Carbon disulfide Nitrogen Carbon dioxide Dissociation data Isochoric method abstract In this communication, dissociation pressures for clathrate hydrates of the carbon disulfide þ nitrogen or carbon dioxide þ water system are reported in the (275.7–281.7) and (274.1–281.2) K temperature ranges, respectively. An isochoric pressure search method was used to perform the measurements. The aforementioned hydrate dissociation data are compared with selected experimental data from the literature for the dissociation conditions of nitrogen and carbon dioxide simple hydrates. It is shown while carbon disulfide has thermodynamic promotion effect on the nitrogen clathrate hydrates it has, however, negligible effect on carbon dioxide hydrates. & 2013 Elsevier Ltd. All rights reserved. 1. Introduction Clathrate hydrates, or gas hydrates, are inclusion compounds composed of water and small (guest) species which can be either gas or particular liquids under room conditions (Sloan and Koh, 2008; Davidson, 1973; von Stackelberg, 1949). They are normally stabilized by the guest molecules enclathrated in hydrogen- bonded water cages (Sloan and Koh, 2008; Davidson, 1973; von Stackelberg, 1949). Clathrate hydrates are known to form generally three typical crystal structures at relatively high pressures and low temperatures, namely structure I (sI), structure II (sII) and structure H(sH) depending on the size and shape of the guest molecule(s) (Sloan and Koh, 2008). Gas hydrates have been reviewed in depth elsewhere (Sloan and Koh, 2008; Davidson, 1973). Indeed, limited information is available in the literature for clathrate hydrates of carbon disulfide (CS 2 )(Sloan and Koh, 2008; Davidson, 1973; von Stackelberg, 1949). It is believed that carbon disulfide forms structure II clathrate hydrate with a help gas (Sloan and Koh, 2008; Davidson, 1973). So far, we studied clathrate hydrates of sulfur dioxide, (Mohammadi and Richon, 2011b) mercaptans (methyl mercaptan or methanethiol; n-propyl mercaptan or 1-pro- panethiol; and n-butyl mercaptan or 1-butanethiol) (Mohammadi and Richon, 2011b, 2012) and carbonyl sulfide (Mohammadi and Richon, 2009a) and we argued that other sulfur compounds likely form clathrate hydrates with a help gas (Mohammadi and Richon, 2011b, 2012, 2009a). There is no phase equilibrium data on clathrate hydrates of carbon disulfide in literature. Contents lists available at SciVerse ScienceDirect journal homepage: www.elsevier.com/locate/ces Chemical Engineering Science 0009-2509/$ - see front matter & 2013 Elsevier Ltd. All rights reserved. http://dx.doi.org/10.1016/j.ces.2013.01.006 n Corresponding author at: MINES ParisTech, CEP/TEP—Centre E ´ nerge ´ tique et Proce ´de ´ s, 35 Rue Saint Honore ´ , 77305 Fontainebleau, France. E-mail addresses: a.h.m@irgcp.fr, amir_h_mohammadi@yahoo.com (A.H. Mohammadi). Chemical Engineering Science 91 (2013) 146–150