William Spackman

Molecular aspects of the peatification and early coalification of angiosperm and gymnosperm woods

Selected genera represented by recent and peatified woods common to the southeastern US and their lignitic equivalents from Vermont and North Dakota have been characterized by Curie-point pyrolysis-mass spectrometry and Curie-point pyrolysis-gas chromatography, mass spectrometry. Pyrolysis data have shown that similar chemical trends are exhibited during the peatification and early coalification of both hardwood and softwood cell wall components. These trends are: 1. (1) the relatively rapid removal of pentosans i.e., hemicelluloses), 2. (2) the initial enrichment followed by the gradual removal of cellulose (and other hexose sugars), and 3. (3) the gradual modification of lignin to a less functionalized aromatic polymer. These observations imply that cell wall-derived huminitic macerals in coals consist predominantly of demethoxylated, demethylated, and more highly condensed lignin derived macromolecules.

Occurrence and distribution of sulfur in peat-forming environments of southern Florida

Abstract Cores and surface samples of peats from the Everglades—Mangrove region of Southern Florida were analyzed for total sulfur and pyritic sulfur. These values were compared with the petrographic-botanical components of the peats as determined from point-counts of oriented microtome sections. Pyrite occurs as individual euhedral crystals, loosely packed framboids, and lenses or crusts of minute crystals. Framboids and minute crystals are often associated with organic matter and sometimes with bacteria and fungi. Pyrite tends to selectively occur in void spaces in or between peat tissues. In samples containing very small amounts of pyrite, framboidal pyrite is the prevalent form. Marine to brackish peats contain the highest pyrite and total sulfur contents, with brackish peats generally containing more pyrite than marine peats. Pyrite tends to be lower in all peats within 30 cm of the surface, whether marine or brackish. Burial of freshwater peats beneath marine or brackish peats tends to increase the total sulfur and pyritic sulfur in the underlying peats. Burial beneath brackish-water, clay-rich deposits (such as splays) tends to increase total sulfur and pyritic sulfur in the underlying deposits more than burial beneath less clay-rich deposits.

Dependence of coal liquefaction behaviour on coal characteristics. 4. Cluster analyses for characteristics of 104 coals

Abstract In an extension of earlier work, the conversion of 104 high volatile bituminous coals at 400 °C with tetralin has been determined in duplicate with the aid of a new reactor system. For the whole set of coals, volatile matter and vitrinite reflectance have the highest correlation coefficients with conversion (0.85 and −0.84, respectively). However, tests showed that the sample set contained more than one population. Cluster analysis partitioned the set into three reasonably homogeneous populations. A factor representing sulphur content was the major contributor from a set of variables in separating the coals into groups, with smaller contributions from factors related to rank and petrographic composition. Each of the groups contained samples mostly from one geological province, but 11 coals of relatively high sulphur content from the Eastern province were clustered in a group that contained also 25 coals from the Interior province. The ranges of conversion are distinctly different for the three groups, and the three regression equations developed for correlating conversion each require a different set of coal properties. The possible general significance of the clustering of coals into groups as a novel basis for classification is discussed.

Dependence of coal liquefaction behaviour on coal characteristics. 2. Role of petrographic composition

Abstract The techniques used were the same as those used in Part 1 (p 34). Comparison of the liquefaction behaviour of two lithotypes from a Kentucky bituminous coal indicated that in this process pseudovitrinite is a reactive maceral. The hydrogenation of sets of maceral concentrates obtained from a New Mexico sub-bituminous and a Kentucky bituminous coal showed fair correlations between conversion and the total concentration of the presumed reactive macerals (vitrinite, pseudovitrinite and sporinite). Similar concentrates from a Montana lignite showed no such correlation; the one sample that showed a high conversion was a high-density fraction that had a high mineral-matter content and in which nearly all the pyrite in the coal had accumulated. Two samples that have boghead and cannel characteristics gave quite different results on hydrogenation. Both were highly aliphatic in structure and had unusually high hydrogen contents and volatile matter. One, which contained appreciable proportions of sporinite, alginite and resinite, gave essentially no conversion to oil. The other, predominantly vitrinitic but containing alginite as the second most abundant maceral, gave an excellent yield of an oil of low viscosity and aromaticity. It was concluded that although rank, petrographic composition and perhaps geological history are important factors determining liquefaction behaviour, there are other characteristics of coals that may at times override these basic parameters, and the composition of the inorganic matter may be the most significant of these other characteristics.

Interpreting the characteristics of coal seams from chemical, physical and petrographic studies of peat deposits

Abstract The purpose of this paper is to illustrate some of the kinds of information about coals that are at present being generated from studies of peat deposits and also to point out some possible new areas of research that might be undertaken in the future. Some notable examples of new ideas about coal seam composition or formation that have been generated from studies of modern peat deposits include: (1) discovery of the probable progenitors of certain coal macerals and elucidation of the processes by which they may have formed; (2) evidence that some types of mineral matter may be dissolved out of peat deposits; (3) verification of the role of marine waters in emplacement of sulphur in peat; (4) discovery of the importance of ‘doming’ in peat deposit development; (5) discovery of a new way to form a split in a coal seam, i.e. development of a ‘fire splay’; (6) elucidation of the mechanisms responsible for producing stratification in coal seams; (7) recognition of the world-wide importance of ‘back-barrier’ coal-forming environments. These kinds of discoveries are important in themselves; however, they can also be shown to have many additional practical applications, especially if woven into models to predict the economic characteristics of coal seams.

Dependence of coal liquefaction behaviour on coal characteristics. 1. Vitrinite-rich samples

Abstract The liquefaction behaviour of a number of vitrinite-rich coals has been determined in batch autoclaves at temperatures of 385–425 °C and pressures of about 8.6 MPa (85 atm) of hydrogen. In one set of experiments, impregnated ammonium molybdate was used as catalyst, with no added liquid as vehicle. In a second set, a proprietary catalyst was used and anthracene oil served as vehicle. Lignites, sub-bituminous, medium-volatile and low-volatile bituminous coals gave relatively poor conversions. However, a lignite sample that had been subjected to ion-exchange treatments gave high conversion, and the viscosity and structural parameters of the products varied with the nature of the treatment. In general the highest conversions were observed for coals in the high-volatile bituminous range, but within this broad range and for the comparatively small set of samples studied neither these data nor the structural characteristics of the products show any very evident correlation with rank parameters or with the geological history of the sample. Two geologically young bituminous coals from the Pacific Coal Province gave excellent conversions; both had very high mineral-matter contents, a fact that may be very relevant.

Methods in Peat Petrology and their Application to Reconstruction of Paleoenvironments

In order to reconstruct the environments of peat deposition in southern Florida and to better understand the coal-forming processes, it was necessary to improve the techniques for collecting and analyzing modern phytogenic sediments. The need for minimizing compaction and distortion of organic sediments during field sampling required the development of a modified piston corer. The partial vacuum created by such a piston reduces compaction and holds the sediment in proper position in the coring tubes on the downstroke as well as during the uplift. Relatively undistorted microtome sections (15μ thick) were cut from oriented samples of peat impregnated with paraffin. By comparison with reference slides of modern plant tissues, it was possible to identify the genera and sometimes the species of plants contributing to the peat even though there were only much-altered fragments of these plants present. Vertically oriented sections are especially useful, because they can be easily compared with thin sections of coals. The method proved successful for study of peats of many different compositions and textures. A field test of the environmental interpretations made from oriented microtome sections showed a very good correspondence between actual surface environments and environments which had been predicted solely from analysis of microtome sections of surface peat. However, describing the vegetation in terms of the relative proportions of particular species proved to be more speculative. A relatively close correspondence was also exhibited between paleoecological interpretations made from oriented microtome sections of peat and those made by palynologic analyses. However, each method has its advantages, and interpretations based on the combined data of both methods are superior to those obtained by using either one alone.

The fate of cellulose and lignin in peats: an exploratory study of the input to coalification

Abstract The plant organs that give rise to preserved tissue in peats are often composed chiefly of cells with cellulosic (unlignified) walls, which frequently retain the birefringence characteristic of cellulose. Yet unaltered polymeric cellulose is present in very low concentration and, if inserted into peat as cotton, is rapidly destroyed. Our objective is to resolve this paradox and also identigy chemical changes undergone by any lignin that escapes depolymerization. Cores of peat from four environments in the Florida Everglades and one in Okefenokee Swamp (Georgia) are being studied. Size separation of peat from various depths by slurrying in water and passing through an 80 mesh sieve is an effective method of segregating rootlets and other plant tissue from fine-grained humic matter. In most cases, the various plant tissue fragments seem to consist chiefly of the principal plant polymers (cellulose and lignin), though these are somewhat oxidized and cellulose tends to decrease with depth. The fine-grained humic matter contains more or less the same structural features as the plant polymers, but shows bands of different shapes and relative intensities. In the case of the Cypress peat (only), the spectra of coarse and fine materials are quite similar. Thus there is evidence that cellulose does survive in some peats and that the polymers can be somewhat altered without destruction of cellular morphology.

The Influence of the Properties of Coals on Their Conversion into Clean Fuels

Abstract Two fundamental controlling factors in the geological histories of coals have determined their physical and chemical characteristics and, consequently, the industrial uses to which they can be put. The first of these is the set of conditions that existed in the original peat swamp, involving the type of vegetation, the nature and extent of the degxadative, preservational, and sedimentary processes, and resulting in varying assemblages of organic macerals and inorganic minerals. Certain of these ingredients are beneficial in conversion processes. The second factor is the nature and degree of the metamorphic changes that the peat deposit underwent during burial within the earths crust. Although coals of lower rank are readily converted into liquid fuels, the highest yields are obtained from coals of high volatile bituminous rank. Microscopic methods of measuring the contribution made by both of the controlling factors (petrographic type and rank) enable workers to compare the conversion potential ...

A microscopic investigation of woody tissues in peats: Some processes active in the peatification of Ligno-cellulosic cell walls

Abstract The formation of huminitic materials from xylem precursors is conventionally described as involving humification and gelification. Our ignorance of the chemical and physical details of these processes has led to confusion regarding the fate of woody tissues in peats. Our objective is to physically define the processes active on xylem cell walls during peatification. Peatified woody fragments from various depths and environments in southwestern Florida and the Okefenokee Swamp were examined microscopically in normal white light, crossed-polarized light, and incident blue light. The examination revealed that three processes were commonly active on woody cell walls during peatification: (1) alteration, (2) degradation, and (3) gelification. Each of these processes is anatomically defined and the optical characteristics of each are used to infer the chemical fate of the major cell wall polymers, cellulose and lignin, during each process. It is hoped that future studies combining chemical analyses and peat petrography will futher define these three processes.