The equilibrium conditions, hydrate formation and dissociation rate and storage capacity of ethylene hydrate in presence of 1,4-dioxane

• Published in: Chemical engineering journal (Lausanne, Switzerland : 1996) Switzerland : 1996), 2013-02, Vol.217, p.379-384
• Main Authors: Manteghian, Mehrdad, Mousavi Safavi, Seyed Mahmoud, Mohammadi, Abolfazl
• Format: Article
• Language: English
• Subjects: 1,4-Dioxane; Applied sciences; Chemical engineering; dioxane; Dissociation; Equilibrium conditions; Ethylene; Ethylene hydrate; Exact sciences and technology; Formation; Formations; heat; Hydrates; Occupation; Solubility; Step heating method; Storage capacity
• ISSN: 1385-8947; 1873-3212
• DOI: 10.1016/j.cej.2012.12.014

► The equilibrium data of hydrate formation for ethylene+1,4-dioxane have been obtained. ► 1,4-Dioxane enhances the storage capacity of ethylene hydrate remarkably. ► The addition of 1,4-Dioxane results in an increase in the hydrate formation pressure. ► 1,4-Dioxane accelerates the hydrate growth rate. ► 1,4-Dioxane decreases dissociation percentage of ethylene hydrate. The effect of 1,4-dioxane on ethylene hydrate was investigated at three additive molar concentrations of 2.78%, 5.56% and 8.34%. The equilibrium conditions for hydrate dissociation were obtained by step heating method. The results showed that addition of 1,4-dioxane concentration increases the pressure of hydrate dissociation. Diagram of Ln(Peq) vs. Teq demonstrated that system of 1,4-dioxane+ethylene+water form ethylene hydrate with structure I. In fact 1,4-dioxane cannot participate in hydrate structure because ethylene molecules are not a good help gas for occupation of S-cages in structure II. So, in this condition only ethylene hydrate with structure I could be formed. The experimental results on hydrate formation indicted that 1,4-dioxane accelerates the hydrate growth rate by increasing the solubility of ethylene in water and a maximum storage capacity of (VSTP/VH)=146 is obtained in a critical dioxane concentration of 5.56% by mole. Also hydrate dissociation experiments revealed that maximum dissociation percentage is related to pure water (48%) and 1,4-dioxane decreases dissociation percentage of ethylene hydrate.