Extending Depletion Flocculation Phase Behavior Models to Partially Soluble and Aggregating Colloids—Asphaltenes by Sayyid Sajjad Pouralhosseini A thesis submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Chemical Engineering Department of Chemical and Materials Engineering University of Alberta © Sayyid Sajjad Pouralhosseini, 2015 Abstract: Mixtures of colloids + non-adsorbing polymers + good solvents are well known to exhibit multiphase behaviors that are driven by the depletion flocculation mechanism where one phase, designated a colloid gas, is largely comprised of polymer and solvent, while the other phase, designated a colloid (liquid or solid), comprises largely solvent + colloid. Qualitative aspects of this behavior are well-understood and quantitative models for the phase behavior of mono-dispersed hard-sphere particles + mono-dispersed non-adsorbing polymers in good solvents, such as the Fleer–Tuinier1 model are well established. In this work, a generalization of the Fleer–Tuinier model for cases where the fraction of colloid that is soluble in a solvent and the size distribution of colloid particles both vary with global composition is described. The impacts of temperature variation, and mean polymer size, on phase diagrams are also treated theoretically and validated experimentally. By incorporating the Ostwald–Freundlich equation, which links the size of nanoparticles to their solubility in the parameterization of the modified Fleer–Tuinier model, the number of parameters that must be identified by fitting experimental data is minimized. Envisioned applications and illustrations are drawn from the hydrocarbon energy sector where, for example, self-assembled nano-aggregates, known as asphaltenes, pose production, pipelining, and refining challenges. The solubility, mean size and size distribution of these self- assembling species are well known to be dependent on global composition. Quantitative fits to measured phase diagrams for Maya2 and Athabasca asphaltenes + polystyrene (non- adsorbing polymer) + toluene (good solvent) at 298 K at fixed polymer mean molar mass are obtained for both mixtures. Variations of the two-phase to single-phase boundaries, critical points, and tie lines with changes in temperature at fixed polymer size and with polymer ii mean size at fixed temperature are then predicted and the outcomes compared with data. The modeling approach, data fitting procedure, and the quality of the predictions, for these illustrative examples, are presented. The importance of these results with respect to the broader development of depletion flocculation models for applications where partially soluble and aggregating colloids arise is discussed. REFERENCES (1) Khammar, M.; Shaw, J.M. Liquid–Liquid Phase Equilibria in Asphaltene + Polystyrene + Toluene Mixtures at 293 K. Energy Fuels 2012, 26 (2), 1075–1088. (2) Fleer, G.J.; Tuinier, R. Analytical Phase Diagrams for Colloids and Non-adsorbing polymer. Adv. Colloid Interface Sci., 2008 143, 1-47. iii Preface: Chapter 2 of this thesis will be combined with Chapter 3, and will then be submitted as S. Pouralhosseini, F. Eslami, J.A.W. Elliott, J.M. Shaw, “Simulating Depletion Flocculation in Asphaltene + Toluene + Polystyrene Mixtures” to the Journal of Fluid Phase Equilibria. I was responsible for the modeling calculations and analysis as well as the manuscript composition. F. Eslami assisted me with the manuscript composition and Ostwald–Freundlich equation calculations. J.A.W Elliott was the supervisory co-author and was involved with concept formation and manuscript editing. Chapter 4 has been accepted as S. Pouralhosseini, M. Alizadehgiashi, and J.M. Shaw, “On the Phase Behavior of Athabasca Asphaltene + Polystyrene + Toluene Mixtures at 298 K” at Energy & Fuels. I was responsible for the data collection and analysis as well as the manuscript composition. M. Alizadehgiashi assisted me with the manuscript composition. Chapter 5 has been accepted as S. Pouralhosseini and J.M. Shaw, “On the Temperature Independent Colloidal Phase Behavior of Maya Asphaltene + Toluene + Polystyrene Mixtures” at Energy & Fuels. It is noteworthy to mention that none of these journal papers and chapters would have been possible without J.M. Shaw’s assistance with concept formulation and manuscript editing. iv Dedication To my parents and my supervisor, I couldn’t have done this without you. Thanks you for all your support along the way. v Acknowledgements It is a genuine pleasure to express my deep sense of thanks and gratitude to my supervisor, Professor Shaw. His dedication and keen interest above all his overwhelming attitude to help his students played the main role in completing my work. His timely advice, meticulous scrutiny, and scientific advice have helped me to a great extent to accomplish this task. I owe deep gratitude to Professor Elliott, for her keen interest on me during my graduate study. Her prompt inspirations with kindness, enthusiasm, and dynamism enabled me to complete my PhD. I also thank profusely for the time and the effort the members of the supervisory and examining committees have spent on reviewing this thesis. Gratitude is also extended to Dr Petersen for the insightful discussions. I am extremely thankful to my parents, brothers, and friends for their unlimited and wholehearted support. I also thank Mildred Becerra, Linda Kaert, Amin Pourmohammadbagher, and Marc Cassiede. I gratefully acknowledge financial support from the sponsors of the NSERC Industrial Research Chair in Petroleum Thermodynamics: the Natural Sciences and Engineering Research Council of Canada (NSERC), Alberta Innovates Energy and Environment Solutions, BP Canada, ConocoPhillips Canada Resources Corp., Nexen Energy ULC, Shell Canada Ltd., Total E&P Canada Ltd., Virtual Materials Group. vi Table of Contents CHAPTER 1: INTRODUCTION ................................ ..................................................................................... 1 OLLOIDS 1. C2.1 van ................................ der Waals ................................ Attraction ................................ .......................................................................................................................................................................................... ........2 1 OLLOIDAL NTERACTIONS 2. C2.2 Electrical I Double ................................ Layer Attraction ................................ ................................................................................................................................................................................ 2 1 2.3 Stern Layer Interaction ................................ .............................................................................................. 3 EPLETION LOCCULATION 3. D F ................................ ........................................................................................................ 4 HASE EPARATION OF OLLOIDAL ARTICLES EDIUM OLYMER IXTURES 4. P S C P + M + P M ................................ ...... 5 SPHALTENE OLLOIDS 5. A C ................................ ............................................................................................................... 6 OLYMER DDITION TO IXTURES NCLUDING SPHALTENES 6. P A M I A ................................ .......................................... 7 REE OLUME HEORY 7. F V T ................................ ................................................................................................................ 8 BJECTIVES 8. O ................................ .................................................................................................................................... 9 HESIS UTLINE 9. T O ................................ ............................................................................................................................ 9 CHAPTER REFERENCES 2: ................................ SIMULATING DEPLETION ................................ ................................ FLOCCULATION IN ................................ ASPHALTENE + ................................ TOLUENE + 10 POLYSTYRENE MIXTURES ................................ ........................................................................................ 14 NTRODUCTION 1. I ................................ ............................................................................................................................ 15 ODIFICATION OF THE LEER UINIER ODEL 2. M3.1 Relative Phase F – Volumes ................................ T M ................................................................ ............................................................................................................................ 29 . 25 ODEL ALIDATION 3. M3.2 Enthalpy V of ................................ Solution ................................ Measurements ................................ for Maya ................................ Asphaltenes in Toluene .............................. ................... 29 29 4.1 Model Parameter Identification ................................ ........................................................................... 32 ESULTS AND ISCUSSION 4. R4.2 Computed D Phase ................................ Diagrams for Maya ................................ Asphaltene ................................ + Toluene ................................ + Polystyrene Mixtures .. 34........ 32 4.3 Model Parameter Validation ...............................