Chapman, JN
1991
Characterization of Lignocellulosic Materials and Model Compounds by Combined TG/(GC)/FTIR/MS
Dworzanski, J.P.; Buchanan, R.M.; Chapman, J.N. and Meuzelaar, H.L.C.
ASC Preprints, Division of Fuel Chemistry, 36(2):725-732, 1991 (201st ACS National Meeting, Atlanta, GA, April 1991). Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction, ACERC, Hewlett Packard Corp. and US Department of Energy.
Thermal analytical methods have been widely used during the last two decades in the study of biomass thermochemical conversion processes. Biomass, which represents a renewable energy resource, consists primarily of plant cells differentiated into characteristic tissues and organs. Lignins, hemicelluloses and cellulose, as the main components of the cell walls, were therefore extensively analyzed, especially from the point of view of their thermochemical reactivity, which is of basic importance for industrial processing of biomass.
All types of cellulose microfibrils are composed of linearly linked b-(1-->4)-D-glucopyranose units and differ only by the degree of polymerization. The remaining polysaccharides are known collectively as hemicelluloses and exhibit species related composition. These amorphous, complex heteropolymers characterized by a branched molecular structure exhibit a lower degree of polymerization than cellulose. Xylan is the predominant hemicellulose component of angiosperms ("hardwoods") whereas mannan forms the main hemicellulose of gymnosperms ("softwoods"). The third principal component of biomass, viz. lignin, is an irregular, high MW polymer formed by enzyme-initiated, free-radical polymerization of coniferyl alcohol (in hardwoods), coniferyl plus sinapyl alcohols (in softwoods), or coumaryl alcohol plus both above mentioned alcohols (in grasses). Lignins act as binding agents for the cellulose and hemicellulose fibers through a variety of linkages involving ether and carbon-carbon bonds of aromatic rings and propyl side chains.
Thermochemical conversion processes of lignocellulosic materials have been studied using mainly thermogravimetry (TG) or flash pyrolysis (Py) followed by gas chromatographic (GC) separation and identification of the reaction products. Modern analytical techniques based on coupled Py-GC/mass spectrometry (Py-GC/MS) or direct Py-MS as well as TG/MS or TG/infrared spectroscopy (TG/IR) have proved to be especially useful for elucidating the relationships between biomass structure and pyrolysis/devolatilization mechanisms.
A novel TG/(GC)/FTIR/MS system developed at the University of Utah, Center for Micro Analysis and Reaction Chemistry provides the opportunity for combining accurate weight loss measurements with precise information about composition and evolution rates of gaseous and liquid products as a function of temperature. In this paper, the usefulness of TG/FTIR/MS, TG/GC/MS and TG/GC/FTIR for thermochemical characterization of wood, lignins and cellulose will be discussed.
Chapman, JN
1991
Characterization of Lignocellulosic Materials and Model Compounds by Combined TG/(GC)/FTIR/MS
Dworzanski, J.P.; Buchanan, R.M.; Chapman, J.N. and Meuzelaar, H.L.C.
ASC Preprints, Division of Fuel Chemistry, 36(2):725-732, 1991 (201st ACS National Meeting, Atlanta, GA, April 1991). Funded by Pittsburgh Energy Technology Center/Consortium for Fossil Fuel Liquefaction, ACERC, Hewlett Packard Corp. and US Department of Energy.
Thermal analytical methods have been widely used during the last two decades in the study of biomass thermochemical conversion processes. Biomass, which represents a renewable energy resource, consists primarily of plant cells differentiated into characteristic tissues and organs. Lignins, hemicelluloses and cellulose, as the main components of the cell walls, were therefore extensively analyzed, especially from the point of view of their thermochemical reactivity, which is of basic importance for industrial processing of biomass.
All types of cellulose microfibrils are composed of linearly linked b-(1-->4)-D-glucopyranose units and differ only by the degree of polymerization. The remaining polysaccharides are known collectively as hemicelluloses and exhibit species related composition. These amorphous, complex heteropolymers characterized by a branched molecular structure exhibit a lower degree of polymerization than cellulose. Xylan is the predominant hemicellulose component of angiosperms ("hardwoods") whereas mannan forms the main hemicellulose of gymnosperms ("softwoods"). The third principal component of biomass, viz. lignin, is an irregular, high MW polymer formed by enzyme-initiated, free-radical polymerization of coniferyl alcohol (in hardwoods), coniferyl plus sinapyl alcohols (in softwoods), or coumaryl alcohol plus both above mentioned alcohols (in grasses). Lignins act as binding agents for the cellulose and hemicellulose fibers through a variety of linkages involving ether and carbon-carbon bonds of aromatic rings and propyl side chains.
Thermochemical conversion processes of lignocellulosic materials have been studied using mainly thermogravimetry (TG) or flash pyrolysis (Py) followed by gas chromatographic (GC) separation and identification of the reaction products. Modern analytical techniques based on coupled Py-GC/mass spectrometry (Py-GC/MS) or direct Py-MS as well as TG/MS or TG/infrared spectroscopy (TG/IR) have proved to be especially useful for elucidating the relationships between biomass structure and pyrolysis/devolatilization mechanisms.
A novel TG/(GC)/FTIR/MS system developed at the University of Utah, Center for Micro Analysis and Reaction Chemistry provides the opportunity for combining accurate weight loss measurements with precise information about composition and evolution rates of gaseous and liquid products as a function of temperature. In this paper, the usefulness of TG/FTIR/MS, TG/GC/MS and TG/GC/FTIR for thermochemical characterization of wood, lignins and cellulose will be discussed.