Surface Activity of Petroleum Derived Lubricants

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SURFACE ACTIVITY OF PETROLEUM DERIVED LUBRICANTS

SURFACE ACTIVITY OF PETROLEUM DERIVED LUBRICANTS Lilianna Z. Pillon

Boca Raton London New York

CRC Press is an imprint of the Taylor & Francis Group, an informa business

CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2011 by Taylor and Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group, an Informa business No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number-13: 978-1-4398-0341-7 (Ebook-PDF) This book contains information obtained from authentic and highly regarded sources. Reasonable efforts have been made to publish reliable data and information, but the author and publisher cannot assume responsibility for the validity of all materials or the consequences of their use. The authors and publishers have attempted to trace the copyright holders of all material reproduced in this publication and apologize to copyright holders if permission to publish in this form has not been obtained. If any copyright material has not been acknowledged please write and let us know so we may rectify in any future reprint. Except as permitted under U.S. Copyright Law, no part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright. com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC), 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com and the CRC Press Web site at http://www.crcpress.com

To David, Sylvia, Monica, and Samantha for their continuing encouragement and support

Contents Preface.......................................................................................................................xi Author..................................................................................................................... xiii Chapter 1 Conventional Refining of Crude Oils....................................................1 1.1 Properties and Compositions of Crude Oils...............................1 1.2 Properties and Compositions of Petroleum Fractions................4 1.3 Solvent Refining of Lube Oils.................................................. 11 1.4 Processing of Cylinder Oils and Bright Stocks........................20 1.5 Composition of Wax Products..................................................24 References........................................................................................... 32 Chapter 2 Nonconventional Processing of Base Stocks....................................... 35 2.1 Hydrofinishing and Hydrotreatment......................................... 35 2.2 Hydrorefining of White Oils....................................................40 2.3 Hydrocracking Process.............................................................44 2.4 Catalytic Dewaxing.................................................................. 50 2.5 Hydroisomerization of Slack Wax............................................ 55 References........................................................................................... 61 Chapter 3 Low-Temperature Fluidity of Base Stocks.......................................... 63 3.1

Effect of Isomerization and Esterification on Melting Points of Molecules.................................................................. 63 3.2 Effects of Crude Oils and Dewaxing on Pour Points of Base Stocks...............................................................................66 3.3 Brookfield Viscosities and Cold Cranking Stimulator Viscosities of Base Stocks........................................................ 71 3.4 Use of Pour Point Depressants and VI Improvers.................... 75 3.5 Processing Effect...................................................................... 81 References........................................................................................... 87 Chapter 4 Oxidation Stabilities of Base Stocks................................................... 89 4.1 Oxidation By-Products............................................................. 89 4.2 Effect of Hydroprocessing........................................................96 4.3 Performance of Antioxidants in Different Base Stocks......... 105 4.4 Antioxidants’ Synergism........................................................ 111 References......................................................................................... 116

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Chapter 5 Interfacial Properties of Base Stocks................................................ 119 5.1

Foaming.................................................................................. 119 5.1.1 Viscosity Effect......................................................... 119 5.1.2 Foam Inhibition......................................................... 126 5.2 Air Entrainment...................................................................... 135 5.3 Stability of Oil/Water Interface.............................................. 140 5.4 Metal Surface Protection........................................................ 147 5.4.1 Rust Inhibition........................................................... 147 5.4.2 Corrosion Inhibition..................................................154 5.4.3 Wear Prevention........................................................ 159 References......................................................................................... 164 Chapter 6 Lubricant Formulation...................................................................... 167 6.1 Industrial and Automotive Lubricants.................................... 167 6.2 Base Stock Selection............................................................... 174 6.3 Use of Synthetic Fluids........................................................... 181 6.4 Additive Selection................................................................... 184 6.5 Use of Surfactants.................................................................. 190 References......................................................................................... 197 Chapter 7 Effects of Additives on Surface Activities of Turbine Oils............... 201 7.1 Base Stock and Additive Performance Requirements............ 201 7.2 Foam Inhibition and Air Entrainment....................................204 7.3 Rust Prevention and Demulsibility.........................................208 7.4 Effect of Demulsifier on Foaming.......................................... 211 7.5 Oxidation Resistance.............................................................. 212 References......................................................................................... 221 Chapter 8 Effects of Base Stocks on Surface Activities of Hydraulic Oils....... 223 8.1 8.2 8.3

Base Stock and Additive Performance Requirements............ 223 Solvency Effect of Naphthenic Oils....................................... 227 Wear Prevention and Oxidation Resistance of Paraffinic Oils........................................................................ 233 8.4 Performance of Synthetic Fluids............................................ 236 8.5 Use of Biodegradable Oils...................................................... 242 References......................................................................................... 245 Chapter 9 Surface Activity of Engine Oils........................................................ 247 9.1 9.2 9.3

Base Stock and Additive Performance Requirements............ 247 Pour Point Depression............................................................ 254 High-Temperature Foaming...................................................260

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9.4 Air Entrainment......................................................................266 9.5 Oxidation Resistance and Wear............................................. 268 References......................................................................................... 276 Chapter 10 Additive Interactions......................................................................... 279 10.1 10.2 10.3 10.4

Rust Inhibitors Synergism...................................................... 279 “Thickening” Effect of VI Improvers.................................... 282 Formulation of Industrial Gear Oils....................................... 286 Oxidation Resistance and Surface Activities of Food-Grade Lubricants.......................................................... 291 10.5 Additive Antagonism and Incompatibility............................. 296 References......................................................................................... 299 Chapter 11 Scope and Limits of Lubricant Testing............................................. 301 11.1 Fresh Oil Testing of Industrial Oils........................................ 301 11.2 Properties of Used Turbine Oils.............................................307 11.3 Fresh Oil Testing of Engine Oils............................................ 311 11.4 Water Contamination.............................................................. 318 References......................................................................................... 323 Chapter 12 Lubricant Storage.............................................................................. 327 12.1 Lubricant Life......................................................................... 327 12.2 Colloidal Stability................................................................... 330 12.3 Low-Temperature Stability..................................................... 333 12.4 Hot-Temperature Stability...................................................... 335 References......................................................................................... 339 Index....................................................................................................................... 341

Preface The term “lubrication” is described as the control of friction and wear between moving surfaces in contact by the introduction of a lubricant. A typical lubricant contains petroleum-derived base stocks and additives. The literature reports that lube oils are by-products of the crude oil-refining process; however, only some crude oils are suitable to produce lube oil base stocks and the finished lubricants represent a high added value group of petroleum products and require high technical expertise to formulate them. The lubricant industry formulates products to meet the performance requirements of different applications, which can range from severe low-temperature fluidity specifications to high-temperature oxidation resistances. Lubricants also need to meet industry surface activity specifications, which describe their properties at the oil/air interface, such as the resistance to foaming and air entrainment; at the oil/water interface, such as emulsification or demulsification; and at the oil/metal interface, such as rust and corrosion inhibition and wear prevention. While there are many books on crude oil refining, I wrote Chapter 1 (Conventional refining of crude oils) and Chapter 2 (Nonconventional processing of base stocks) to provide readers with an easy access to information. The selection of base stocks depends on whether the level of performance required can be achieved by the use of conventionally refined petroleum-derived base stocks, called mineral base stocks. The majority of lubricant products use mineral base stocks produced by vacuum distillation, solvent extraction, and solvent dewaxing of lube oil distillates. Some lubricant applications require higher-quality base stocks and the use of nonconventional processing based on severe hydrotreating, hydrocracking, or hydroisomerization of different petroleum-derived feedstocks. Many different synthetic fluids are also available; however, their cost versus performance is a key issue. When using synthetic oil instead of petroleum-derived base stocks, the surface activity requirements of some lubricants and their performances need to be carefully compared. While hundreds of additives are available to improve the properties of the petroleum-derived lube oil base stocks, their effectiveness is limited as shown in Chapter 3 (Low temperature fluidity of base stocks), Chapter 4 (Oxidation stability of base stocks), and Chapter 5 (Interfacial properties of base stocks). To formulate the lubricants, the proper base stocks and the proper additives need to be selected as discussed in Chapter 6 (Lubricant formulation). The finished lubricant products need to meet specific performance targets as discussed in Chapter 7 (Effects of additives on surface activity of turbine oils), Chapter 8 (Effects of base stocks on surface activity of hydraulic oils), and Chapter 9 (Surface activity of engine oils). When formulating the lubricants, the additive interactions (Chapter 10), the testing (Chapter 11), and the storage (Chapter 12) is also important. This book will be of interest to any petroleum chemist or engineer involved in the refining of crude oils, in the processing of lube oil base stocks, or in the formulation of finished lubricants, their marketing, testing, and new additive development. xi

Author Lilianna Z. Pillon received her MSc in chemistry from the University of Lodz, Poland, and her PhD from the University of Windsor, Canada. She was awarded a National Research Council (NRC) of Canada Postdoctoral Fellowship and studied polymer blends at the NRC Industrial Materials Research Institute in Boucherville, Quebec. She joined Polysar Ltd., Latex R&D Division, where she developed an interest in polymer emulsions and chemical interactions. She also worked for Imperial Oil, Research Department in the lube oil base stock processing and quality area followed by work in the industrial oil group and the engine oil group. She was awarded patents related to the interfacial properties of lube oil base stocks and the use of surface active additives. She is the author of the book Interfacial Properties of Petroleum Products, published by CRC Press in 2007.

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Refining 1 Conventional of Crude Oils 1.1  Properties and Compositions of Crude Oils Petroleum and the equivalent term crude oil is a mixture of gaseous, liquid, and solid molecules that occurs in rock deposits found in different parts of the world. The initial pressure is sufficient to move oil to the production wells and is called the primary oil recovery. Molecules found in crude oils can exist in various states of matter—gas, liquid, or solid—depending on their chemistry, molecular weight, temperature, solvency, and pressure. With a decrease in the temperature, the clusters of wax crystals can grow until no flow is observed, which is reported as the pour point. Crude oils contain hydrocarbons and heteroatom molecules that in turn contain sulfur (S), nitrogen (N), and oxygen (O), and even some metals such as nickel (Ni), vanadium (V), and iron (Fe). Some crude oils are acidic, as indicated by a high total acid number (TAN), and have a significant carbon residue (CCR) and ash content when exposed to high temperatures. The properties and composition of typical crude oils obtained using primary recovery are shown in Table 1.1. When the initial pressure decreases, it is necessary to increase the pressure by injecting water, which is called the secondary recovery or water flooding. Crude oil recovery from porous sedimentary rocks depends on the efficiency with which oil is displaced by some other fluids. The effect of brine composition on oil recovery by water flooding was studied. The injection of brine containing 2% of KCl and 2% of NaCl increased the oil recovery by 18.8% over the injection of distilled water (Bagci, Kok, and Turksoy, 2001). The total recovery by the primary and secondary recoveries is usually less than 40% of the original oil and the remaining oil is recovered during the tertiary oil recovery also known as enhanced oil recovery (EOR). The literature reports on several proven techniques for the EOR, such as surfactant–polymer flooding, foam flooding, CO2 flooding, caustic solution flooding, microbial method, steam injection, and thermal combustion. It also reports that the most promising EOR technique is the use of surfactants (Ling, Lee, and Shah, 1986). The typical properties and composition of crude oils obtained using EOR are shown in Table 1.2. Crude oil is a mixture of organic compounds ranging in size from simple gaseous molecules to high molecular weight wax and asphaltenes. Wax type molecules reduce the flowability or pumpability of crude oils. For some crude oils, a significant increase in acids will cause a high TAN. Some crude oils contain a large amount of metals and inorganic salts and an increase in CCR will be observed. The literature reports on the variations in wax, sulfur, metals, salts, and asphaltenes of Chinese crude oils (Liu, Xu, and Gao, 2004). 1

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Surface Activity of Petroleum Derived Lubricants

TABLE 1.1 Properties and Composition of Crude Oils Obtained Using Primary Recovery Primary Recovery Gravity (API) Viscosity at 38°C (cP) Pour point (°C) Carbon (wt%) Hydrogen (wt%) Sulfur (wt%) Nitrogen (wt%) Nickel (ppm) Vanadium (ppm) Iron (ppm) Water (wt%) TAN (mg KOH/g) CCR (wt%) Ash (wt%)

Crude Oil #1

Crude Oil #2

Crude Oil #3

10.4 30,200 18 85.4 11.2 2.5 1.2 51 127 8