Ultradispersed particles in heavy oil: Part II, sorption of H 2 S (g) Nashaat N. Nassar a, ⁎, Maen M. Husein a,b, ⁎, Pedro Pereira-Almao a,b a Alberta Ingenuity Centre for In-Situ Energy, University of Calgary, Calgary, Alberta, Canada b Department of Chemical and Petroleum Engineering, University of Calgary, Calgary, Alberta, Canada abstract article info Article history: Received 3 January 2009 Received in revised form 5 August 2009 Accepted 17 September 2009 Keywords: H 2 S Sorption Heavy oil Metal oxide Sorbent During steam assisted gravity drainage for heavy oil recovery aqua-thermolysis reactions take place, whereupon gaseous hydrogen sulfide, H 2 S (g) , is produced. A method to capture H 2 S (g) and convert it into a chemically inactive species is deemed necessary for sustaining in-situ recovery and upgrading. Part I of the current study explored the formation and stabilization of colloidal FeOOH particles in heavy oil matrices. In this Part, we evaluate the H 2 S (g) sorption ability of these particles as well as other metal oxide/hydroxide particles. Furthermore, the effect of mixing and temperature on H 2 S (g) sorption was investigated. Results showed that the rate and capacity of H 2 S (g) sorption increased as the concentration of FeOOH increased. Mixing, on the other hand, had insignificant effect on the sorption capacity, however it improved the sorption kinetics. In addition, in-situ prepared colloidal particles showed better reactivity towards H 2 S (g) than commercial α-Fe 2 O 3 nanoparticles. Temperature had an adverse effect on the H 2 S (g) sorption capacity of FeOOH. This was attributed to a change in chemical structure of FeOOH as the temperature increased. Nevertheless, in-situ prepared ZnO colloidal particles completely removed H 2 S (g) even at high temperatures. Crown Copyright © 2009 Published by Elsevier B.V. All rights reserved. 1. Introduction With the continuous depletion of the world's supply of conven- tional oil, there is an increasing demand for recovering and upgrading of heavy oil and bitumen to meet current and future energy needs of the world. However, due to the high viscosity and specific gravity of heavy oil its ability to flow within the reservoir is low [1–4]. Two thermal recovery techniques have been employed to raise the temperature of heavy oil and reduce its viscosity, in-situ combustion and steam injection. Steam injection, known as steam assisted gravity drainage (SAGD), is the most common and effective recovery method [5,6]. In SAGD, the steam is used as the heat carrier to increase the temperature and reduce the viscosity of heavy oil, and consequently reduce the flow resistance of heavy oil through porous media which increase the yield and production rate [5,6]. However, heavy oil recovering and upgrading has been proven to be environmentally unfriendly [7]. During viscosity reduction a number of chemical reactions between steam and heavy oil take place [2,8,9]. The production of hydrogen sulfide and carbon dioxide in addition to other minor gaseous pollutants is common during SAGD process [2,8,9]. Aqua-thermolysis, which describes the chemical interaction of high temperature and high pressure steam with reactive components of heavy oil, leads to breaking the C―S bond in heavy oil [2].H 2 S (g) is a highly toxic and odorous gas that can impact underground water and contribute for the acid rain formation as well. Moreover, H 2 S (g) can cause pipeline corrosion, poison catalysts and limit plant lifetime [10]. Thus, a method to capture H 2 S (g) and convert it to a chemically inactive product during in-situ recovery and upgrading is necessary. In a previous work, we showed that ultradispersed colloidal FeOOH particles formed in-situ in 1-methyl naphthalene continuous oil phase by means of (w/o) microemulsion methods effectively converted H 2 S (g) into FeS and S 0 [1]. In addition, our previous work showed that commercial α-Fe 2 O 3 nanoparticles as well as soluble FeCl 3(aq) dispersed in the same background microemulsions were ineffective towards H 2 S (g) capturing within the residence time of the gas bubbles [1]. Part I of the current work investigated the formation and stabilization of colloidal FeOOH particles in heavy oil matrices. Results from Part I showed that appreciable concentration of colloidal FeOOH particles could be maintained stable for more than 48 h. Part II of the current investigation explores the effectiveness of the ultradispersed colloidal FeOOH particles in capturing H 2 S (g) while it bubbles through the heavy oil. In-situ prepared FeOOH were compared with commercial iron oxide nanoparticles. In addition, other metal oxides; including MgO, CaO and ZnO were tested towards H 2 S (g) sorption, especially at higher temperature. Packed columns of these metal oxide particles have been shown to effectively remove H 2 S (g) [10–14]. The present work holds great promise for online removal of H 2 S (g) during in-situ heavy oil recovery and upgrading [7]. Example of potential application of in-situ prepared colloidal metal oxide particles is illustrated in Fig. 1. Fuel Processing Technology 91 (2010) 169–174 ⁎ Corresponding authors. E-mail addresses: nassar@ucalgary.ca (N.N. Nassar), maen.husein@ucalgary.ca (M.M. Husein). 0378-3820/$ – see front matter. Crown Copyright © 2009 Published by Elsevier B.V. All rights reserved. doi:10.1016/j.fuproc.2009.09.008 Contents lists available at ScienceDirect Fuel Processing Technology journal homepage: www.elsevier.com/locate/fuproc