Carbons and Carbon-Supported Catalysts in Hydroprocessing (Rsc Catalysis Series) - Hardcover

Furimsky, Edward

Hardcover

ISBN 10: 0854041435 ISBN 13: 9780854041435

Verlag: Royal Society of Chemistry, 2008

Inhaltsangabe

Carbon materials have, in recent years, been attracting attention as potential supports in heterogeneous catalysis. In 2006, the number of articles dealing with various types of catalysts supported on carbon approached 1000, however only a fraction of those were devoted to hydroprocessing catalysts, despite the fact that interest in carbons as supports for hydroprocessing catalysts began more than two decades ago. This unique book is a comprehensive summary of recent research in the field and covers all areas of carbons and carbon materials. The potential application of carbon supports, particularly those of carbon black (CB) and activated carbon (AC) in hydroprocessing catalysis are covered extensively in the book. Novel carbon materials such as carbon fibers and carbon nano tubes (CNT) are also covered, including the more recent developments in the use of fullerenes in hydroprocessing applications - an area with little published research. Although the primary focus of this book is on carbons and carbon supported catalysts, it also identifies the difference in the effect of carbon supports compared with the oxidic supports, particularly that of Y-AL2 O3. Although many books claim to have the same objective, this publication is unique as the difference in catalyst activity and stability was estimated using both model compounds and real feeds under variable conditions. The conditions applied during the preparation of carbon supported catalysts are also comprehensively covered and include various methods of pretreatment of carbon supports to enhance catalyst performance. The model compounds results consistently show higher hydrodesulfurization and hydrodeoxygenation activities of carbon supported catalysts than that of the ?-Al2O3 supported catalysts. Also, the deactivation of the former catalysts by coke deposition was much less evident. Importantly, in this book, most of the model compounds studies on hydrodesulfurization and hydrodeoxygenation were conducted in the absence of nitrogen compounds, as the poisoning effects of such compounds on hydroprocessing reactions are well known. Non-conventional metals (e.g., Pt, Pd, Ru, Rh, Re and Ir) supported on carbon supports are also studied in this book as catalysts for hydroprocessing of model feeds and real feeds. The book shows that these catalysts are much more active than conventional metals containing catalysts however the high cost of these metals prevents commercial utilization of these catalysts. Kinetics of hydroprocessing reactions, as well as kinetics of deactivation over carbon supported catalysts are also investigated under a wide range of experimental conditions and the ?-Al2O3 supported catalysts have been included for comparison. This book, unique in its field, indicates the future potential of carbon supported catalysts during hydroprocessing, particularly in deep hydrodesulfurization and hydrodemetallization.

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Über die Autorinnen und Autoren

Dr Edward Furimsky has over 40 years of experience in research on conversion of petroleum and coal involving catalytic processes. He is the author and/or co-author of some 130 articles published in referred scientific journals including several authoritative reviews, e.g., Catalyst Deactivation and Regeneration, Hydrogen Activation, Hydrodenitrogenation of Petroleum, Hydrodeoxygenation and others. His other recent book on Catalyst for Upgrading Heavy Petroleum Feeds provides detailed accounts of problems in designing and selecting suitable catalysts for upgrading problematic petroleum feeds.

Dr Edward Furimsky has over 40 years of experience in research on conversion of petroleum and coal involving catalytic processes. He is the author and/or co-author of some 130 articles published in referred scientific journals including several authoritative reviews, e.g., Catalyst Deactivation and Regeneration, Hydrogen Activation, Hydrodenitrogenation of Petroleum, Hydrodeoxygenation and others. His other recent book on Catalyst for Upgrading Heavy Petroleum Feeds provides detailed accounts of problems in designing and selecting suitable catalysts for upgrading problematic petroleum feeds.

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Carbons and Carbon Supported Catalysts in Hydroprocessing is a comprehensive summary of recent research in the field and covers all areas of carbons and carbon materials. The potential application of carbon supports, particularly those of carbon black (CB) and activated carbon (AC) in hydroprocessing catalysis are covered extensively in the book. Novel carbon materials such as carbon fibers and carbon nano tubes (CNT) are also covered, including the more recent developments in the use of fullerenes in hydroprocessing applications - an area with little published research. Although the primary focus of this book is on carbons and carbon supported catalysts, it also identifies the difference in the effect of carbon supports compared with the oxidic supports, particularly that of y-Al2O3. Although many books claim to have the same objective, this publication is unique as the difference in catalyst activity and stability was estimated using both model compounds and real feeds under variable conditions. The conditions applied during the preparation of carbon supported catalysts are also comprehensively covered and include various methods of pretreatment of carbon supports to enhance catalyst performance. The model compounds results consistently show higher hydrodesulfurization and hydrodeoxygenation activities of carbon supported catalysts than that of the y-Al2O3 supported catalysts. Also, the deactivation of the former catalysts by coke deposition was much less evident. Importantly, in this book, most of the model compounds studies on hydrodesulfurization and hydrodeoxygenation were conducted in the absence of nitrogen compounds, as the poisoning effects of such compounds on hydroprocessing reactions are well known. Non-conventional metals (e.g., Pt, Pd, Ru, Rh, Re and Ir) supported on carbon supports are also studied in this book as catalysts for hydroprocessing of model feeds and real feeds. The book shows that these catalysts are much more active than conventional metals containing catalysts however the high cost of these metals prevents commercial utilization of these catalysts. Kinetics of hydroprocessing reactions, as well as kinetics of deactivation over carbon supported catalysts are also investigated under a wide range of experimental conditions and the y-Al2O3 supported catalysts have been included for comparison. This book, unique in its field, indicates the future potential of carbon supported catalysts during hydroprocessing, particularly in deep hydrodesulfurization and hydrodemetallization.

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Carbons and Carbon-Supported Catalysts in Hydroprocessing

By Edward Furimsky

The Royal Society of Chemistry

Copyright © 2008 Edward Furimsky
All rights reserved.

ISBN: 978-0-85404-143-5

Contents

Chapter 1 Introduction, 1, 
Chapter 2 Industrial Carbons, 
Chapter 3 Hydroprocessing Catalysts, 
Chapter 4 Hydrogen Adsorption, Activation and Transfer by Carbons, 
Chapter 5 Catalytic Activity of Carbons, 
Chapter 6 Carbon-Supported Catalysts, 
Chapter 7 Kinetics and Mechanism of Hydroprocessing Reactions over Carbon and Carbon-Supported Catalysts, 
Chapter 8 Catalyst Deactivation, 
Chapter 9 Patent Literature, 135, 
Chapter 10 Conclusions, 137, 
References, 139, 
Subject Index, 151, 

CHAPTER 1

Introduction

Carbon materials have been attracting attention as potential supports in heterogeneous catalysis. Thus, only in 2006, the number of articles dealing with various types of catalysts supported on carbon approached 1000. Among these, only a fraction was devoted to hydroprocessing catalysts. It is, however, emphasized that interest in carbonss as supports for hydroprocessing catalysts began more than two decades ago. The available information indicates some beneficial effects, although overall, there might be some limitations on the use of carbon materials as the supports for hydroprocessing catalysts.

Carbons that are used industrially exist in a highly ordered crystalline form (diamond and graphite) and a less ordered amorphous form. Figure 1 depicts models of these carbons. Amorphous forms of carbons such as carbon black (CB) and activated carbon (AC) have been used in various industrial applications most extensively. Novel carbon materials, e.g., carbon nanotubes (CNT), fullerenes, etc. have been developed. The information on the individual types of carbon is so extensive that a separate book can be written on each of them.

In catalysis, AC, CB, CB composites (CBC), graphite and graphitized materials have been attracting attention as potential supports for precious metals containing catalysts used for hydrogenation (HYD) of various organic compounds. Because of a weak interaction, a true alloy phase can be created from different metals on some carbon surfaces. This enhances the dispersion of metals and their utilization during alloy catalysis. To some extent, surface defects on carbon supports may be responsible for the interaction with metals. Such alloys cannot be formed on oxidic supports because of their much stronger interaction. An increasing number of studies indicating potential application of carbon supports, particularly those of AC and CB, in hydroprocessing catalysis have been noted. Carbon fibers and CNT have been attracting attention as well, whereas so far little information supports the use of fullerenes in hydro-processing applications.

Although the primary focus of this review was carbon and carbon-supported catalysts, attempts have been made to identify the difference in the effect of carbon supports compared with the oxidic supports, particularly that of γ-Al2O3. It has been noted that many studies had the same objective. For this purpose, the difference in catalyst activity and stability was estimated using both model compounds and real feeds under variable conditions. The conditions applied during the preparation of carbon-supported catalysts have received attention as well. This included various methods of pretreatment of carbon supports to enhance catalyst performance. In spite of all these efforts, commercial utilization of the carbon-supported catalysts in hydroprocessing is rather limited. In this regard, additional research may be needed to identify suitable applications.

Because of the neutral nature and little interaction with active metals, carbon supports are suitable to study the structure of active phase without interference as is usually the case of oxidic supports. Consequently, the understanding of the active phase in hydroprocessing catalysts was significantly advanced. Carbons alone exhibit activity in some hydroprocessing reactions. The ability of carbons to adsorb and activate hydrogen may be the origin of their catalytic activity.

CHAPTER 2

Industrial Carbons

A cursory account of the carbon types (AC, CB, CBC, CNT, fullerenes and graphite) that have been attracting attention for potential applications in hydroprocessing catalysis is given, with focus on the properties and methods of preparation, as well as some industrial applications.

2.1 Carbon Black

Figure 1 shows that CB is an amorphous solid characterized by degenerate or imperfect graphitic structures. In these structures, the angular displacement of one layer with respect to another is random and the layers overlap irregularly thus, forming a turbostratic structure. Within the particles of CB, the crystallites are arranged randomly. The microstructure of CB aggregates consists of a concentric arrangement of layer planes, with the interior of the aggregate being less ordered than the exterior. Also, the interior is more chemically reactive and has a lower density. Thus, during exposure to O2, the oxidation begins at the interior of the aggregate. Structure, determined by the size and shape, as well as the number of particles per aggregate, is another important parameter of CB. The structure influences packing and volume of voids in the aggregate. Chemically, carbon blacks contain about 99% of carbon with hydrogen, oxygen, sulfur, nitrogen and ash accounting for the rest. The content of the noncarbon components determines the surface reactivity of CB. This depends on the method of preparation and the origin of the feed from which CB was made. The particle diameter of most of the CBs is less than 0.5 mm, i.e. a large portion of the CB particles is in the nanosize range.

Carbon black is produced by partial combustion or pyrolysis of hydrocarbon liquids or gases, although attempts have been made to produce carbon black from coal. Particle size, structure (aggregate size) and surface area are among the important properties of CB. Structure refers to the size of the primary aggregates. Thus, CB consisting of many prime particles with extensive branching and chaining is referred to as a high structure, while CB with fewer particles forming more compact units as low-structure blacks. The amorphous nature of CBs results from a short residence time (<1 s) in the reaction zone, i.e. not enough time was left for crystallization, in spite of rather high temperatures employed (~1200 K).

Several dozen grades of CB have been available commercially. Among them, a high-abrasion grade accounts for almost half of the CBs production. Other grades include super-abrasion, intermediate super-abrasion, general purpose, high modulus, semi-reinforcing and fast extrusion CBs. Large volumes of CB have been consumed in the production of rubber (tire and nontire) and other plastics. This is followed by the printing industry for production of various inks. The commercial production of CB has been dominated by an oil-furnace process. In this case, a heavy feed is pyrolyzed with the aid of heat produced by combustion of natural gas. High yield (45 to 65%) and a wide range of grades can be prepared by this process. The gas-furnace process has been gradually displaced by the oil-furnace process. The former is based on the partial combustion of natural gas in the refractory lined reactor. In this case, yields of blacks are less than 30%.

In hydroprocessing catalysis, carbon blacks can be used either directly by...

Details zur Ausgabe

• Verlag: Royal Society of Chemistry
• Erscheinungsdatum: 2008
• Sprache: Englisch
• ISBN 10: 0854041435
• ISBN 13: 9780854041435
• Einband: Gebundene Ausgabe
• Auflage: 1
• Anzahl der Seiten: 159
• Kontakt zum Hersteller: Nicht verfügbar
• Verantwortliche Person: Nicht verfügbar