Cellulose Hydrolysis

ISBN-13: 9783642725777 / Angielski / Miękka / 2011 / 198 str.

Liang-Tseng Fan; Mahendra M. Gharpuray; Yong-Hyun Lee

Opis

Recent economic trends, especially the worldwide decline in oil prices, and an altered political climate in the United States have combined to bring about major reductions in research on renewable energy resources. Yet there is no escaping the "facts of life" with regard to these resources. The days of inexpensive fossil energy are clearly numbered, the credibility of nuclear energy has fallen to a new low, and fusion energy stands decades or more from practical realization. Sooner than we may wish, we will have to turn to renewable raw materials - plant "biomass" and, especially, wood - as significant suppliers of energy for both industry and everyday needs. It is therefore especially important to have a single, comprehensive and current source of information on a key step in any process for the technological exploitation of woody materials, cellulose hydrolysis. Further more, it is essential that any such treatment be unbiased with respect to the two methods - chemical and biochemical - for the breakdown of cellulose to sugars. Researchers on cellulose hydrolysis have frequently been chided by persons from industry, especially those individuals concerned with determining the economic feasibility of various technological alternatives. They tell us that schemes for the utilization of wood and other such resources fly in the face of economic realities."

Spis treści

1 Introduction.- References.- 2 Nature of Cellulosic Material.- 2.1 Components of Cellulosic Materials.- 2.1.1 Extraneous Materials.- 2.1.2 Polysaccharides.- 2.1.3 Lignin.- 2.2 Composition of Wood and Straw.- 2.3 Structure of Plant Cell Walls.- 2.4 Structure of Cellulose.- 2.4.1 Chemical and Molecular Structure of Cellulose.- 2.4.2 Structure and Morphology of Cellulose Fibers.- References.- 3 Enzymatic Hydrolysis.- 3.1 Nature of Lignocellulosic Structural Resistance.- 3.1.1 Degree of Water Swelling of Cellulose Fiber.- 3.1.2 Crystallinity of Cellulose.- 3.1.3 Molecular Structure of Cellulose.- 3.1.4 Extraneous Material — Lignin.- 3.1.5 Presence of Substituent Groups.- 3.1.6 Capillary Structure of Cellulose.- 3.2 Properties and Mode of Cellulase Biodegradation.- 3.2.1 Effect of Cellulase on some Properties of Cellulose Fibers.- 3.2.1.1 Fragmentation of Cellulose Fibers.- 3.2.1.2 Swelling of Cellulose Fibers and the Swelling Factor.- 3.2.2 Mode of Action of the Cellulase.- 3.2.2.1 (C1-Cx) Concept.- 3.2.2.2 ?-1,4-Glucan Cellobiohydrolase.- 3.2.2.3 Cx Components.- 3.2.2.4 ?-Glucosidase.- 3.2.2.5 Synergism Among Components.- 3.2.3 Physical Properties of Cellulase.- 3.2.3.1 Molecular Weights of Cellulase Components.- 3.2.3.2 Diffusion Coefficient and Sedimentation Constant of Cellulase.- 3.2.3.3 Size and Shape of Cellulase Molecules.- 3.3 Pretreatment Methods.- 3.3.1 Physical Pretreatments.- 3.3.1.1 Milling and Grinding.- 3.3.1.2 Pyrolysis.- 3.3.1.3 High Energy Radiation.- 3.3.1.4 High Pressure Steaming.- 3.3.1.5 Extrusion and Expansion.- 3.3.1.6 Microwave Treatment.- 3.3.2 Chemical Pretreatments.- 3.3.2.1 Alkalis.- 3.3.2.2 Acids.- 3.3.2.3 Gases.- 3.3.2.4 Oxidizing Agents.- 3.3.2.5 Cellulose Solvents.- 3.3.2.6 Solvent Extraction.- 3.3.2.7 Swelling Agents.- 3.3.3 Biological Pretreatments.- 3.3.4 Economic Analysis of Pretreatments.- 3.4 Kinetics of Enzymatic Hydrolysis of Cellulose.- 3.4.1 Kinetic Characteristics of the Heterogeneous Cellulose-Cellulase System.- 3.4.1.1 Mass Transfer Limitation — Diffusion of Enzyme.- 3.4.1.2 Adsorption and Desorption of Enzyme.- 3.4.1.3 Surface Reaction, Fragmentation, and Changes of Surface Area During Hydrolysis.- 3.4.1.4 Product Inhibition and its Mechanism.- 3.4.2 Kinetic Models of Insoluble Cellulose Hydrolysis by Cellulase.- 3.4.2.1 Empirical Representations of the Kinetics of Enzymatic Hydrolysis.- 3.4.2.2 Michaelis-Menten Mechanism Applied to an Insoluble Cellulose-Cellulase System.- 3.4.2.3 McLaren’s Approach to Enzyme Reactions in a Structurally Restricted System.- 3.4.2.4 Kinetic Models Based on the Combination of the Enzyme Adsorption Equation and the Michaelis-Menten Type Equation.- 3.4.2.5 Kinetic Model Based on the Depolymerization Mechanism.- 3.4.2.6 Distributed Parameter Kinetic Models.- 3.4.2.7 Mechanistic Kinetic Model.- 3.4.2.8 Miscellaneous Models.- 3.4.3 Kinetics of Cellulases on ?-l,4-O1igoglucosides.- 3.4.4 Kinetics of ?-Glucosidase.- Nomenclature.- References.- 4 Acid Hydrolysis of Cellulose.- 4.1 Mechanism of Acid Hydrolysis.- 4.1.1 Course of Hydrolysis Reaction.- 4.1.2 Identification of Mechanism.- 4.1.3 Degree of Polymerization.- 4.1.4 Recrystallization.- 4.2 Kinetics of Acid Hydrolysis of Cellulose.- 4.2.1 Homogeneous Kinetics.- 4.2.2 Heterogeneous Kinetics.- Nomenclature.- References.- 5 Design and Economic Evaluation of Cellulose Hydrolysis Processes.- 5.1 Enzymatic Hydrolysis.- 5.1.1 Pure Cellulose Substrate.- 5.1.2 Lignocellulosic Substrate.- 5.2 Acid Hydrolysis.- 5.2.1 Dilute Sulfuric Acid Processes.- 5.2.2 Concentrated Sulfuric Acid Processes.- 5.2.3 Hydrochloric Acid Processes.- 5.2.4 Hydrofluoric Acid Process.- Nomenclature.- References.- 6 Epilogue.- Author Index.