Conrad C. Hinckley

Mössbauer studies of iron in Lurgi gasification ashes and power plant fly and bottom ash

Iron Mossbauer spectroscopy and X-ray diffraction methods were applied to the study of a selection of ashes produced in a Lurgi gasification plant and fly ash from a pulverized coal combustion. The ashes contained hematite, magnetite, and goethite. Sixty percent or more of the iron in these ashes was in the oxide form, with the remainder present in mullite and other silicate phases. Iron was divalent in the latter, and present as both Fe+2 and Fe+3 in mullite. Ratios of Fe+2 and Fe+3 varied from 0.3 to 0.7. By comparison, a water-quenched molten bottom ash was free of iron oxides and contained only amorphous silicate phases with virtually all iron in the divalent state.

Catalytic exchange and hydrogenolysis of thiophenes and related heterocycles

Abstract The exchange and hydrogenolysis (deuteriumolysis) of thiophene, 2-methylthio-phene, 3-methylthiophene, 2,5-dimethylthiophene, furan and γ-picoline were examined over a Mo γ- alumina catalyst. The exchange of thiophene and γ-picoline were examined over γ-alumina, Mo γ- alumina and CoMo γ- alumina catalysts. Three types of exchange functions seem to exist in the last two catalysts, random exchange and multiple exchange on γ-alumina and α-exchange on Mo. Poisoning with picoline and water suppresses γ-alumina type exchange but not α-exchange and desulfurization. Multiple exchange is correlated with hydrogenation/dehydrogenation activity and α-exchange is correlated with desulfurization. π-Complex formation seems important in multiple exchange but methyl group exchange requires, in addition, heteroatom activation. The role of Co may be to facilitate surface hydrogen mobility and thereby decrease coke formation.

Iron partitioning in oil shale of the Green River Formation, Colorado: A preliminary Mössbauer study

Abstract Oil shale of the Green River Formation (Eocene) in the Piceance Creek Basin, Colorado contains seven major iron-bearing minerals: pyrite, marcasite, pyrrhotite, Mg-siderite, Fe-dolomite, ankerite and Ca-ankerite. Only recently have workers recognized that these rocks contain large quantities of iron-bearing carbonate minerals. Preliminary Mossbauer spectroscopy analysis of four oil-shale and two marlstone samples from the Green River Formation shows that the dominant iron-bearing compound is usually an iron-carbonate mineral, generally Ca-ankerite or Fe-dolomite. The second most abundant iron-bearing phase is an iron sulphide, generally pyrite. In the samples studied, the iron partitioning is variable between the carbonate and sulphide phases. Lower grades of oil shale and marlstone also have an iron-bearing silicate phase, which is perhaps an iron-bearing phyllosilicate, possibly chlorite.

Mössbauer spectroscopic studies of the mineralogical changes in coal as a function of cleaning, pyrolysis, combustion and coalconversion processes

Abstract The mineralogical changes in a Perry County, Illinois coal from the Herrin (No. 6) Member due to cleaning, pyrolysis, combustion, and coal-conversion processes were studied. Mossbauer spectroscopy was used in tandem with X-ray diffraction to follow the changes in the forms of iron originally present in the coal resulting from processing. The chemistry of the pyrite conversion is less complex than expected. Iron does not become uniformly distributed in all possible minerals but tends to form simple products. Pyrrhotites along with spinel and hydrated ferrous sulphates are the primary mineral products found in coat liquefaction and pyrolysis process residues; while mullite, ferrous silicates and the iron oxides (hematite, geothite and magnetite) are the most abundant mineral products found in Lurgi gasification and power plant fly ashes. The detailed distribution of iron, however, is dependent upon conditions in the particular process equipment in which the coal is used and the conversion process in which it is used.

Kinetics and mechanisms of iron sulfide reductions in hydrogen and in carbon monoxide

The reduction of iron sulfides by hydrogen and by carbon monoxide has been studied using plug flow and thermogravimetric methods. The reactions were studied in the 523-723/sup 0/K temperature range and were found to be first-order processes. Plug flow studies were used to correlate reactions rates between pyrite and the gases as a function of the surface area of the pyrite. The rate of H/sub 2/S formation increases with the surface area of the pyrite sample. The results of thermogravimetric experiments indicate that the reactions consist of several steps. Rate constants for the pyrite reduction by H/sub 2/ and by CO were obtained. The activation energies increased with degree of reduction. Value of E/sub a/ were 113.2 (step I) and 122.5 kJ/mole (step II) for pyrite reduction with CO and 99.4 (step I), 122.4 (step II), 125.2 (step III), and 142.6 kJ/mole (step IV) for pyrite reduction with hydrogen.

Mössbauer studies of illites and heat-treated illite as related to coal-conversion processes

Abstract Mossbauer spectra of iron species in the following illites were studied: Grundite, Fithian, Minerva, and New Albany. Spectra of samples of Fithian illite heated at temperatures of 225, 700, and 1000 °C were also obtained. Analyses of these spectra provide Mossbauer parameter values of iron species in the illites and heat-transformed illite for comparison with similar species found in coals containing illites and in coal process residues derived from them. The illites contain both ferric and ferrous species. Mossbauer parameters for one of the ferric species, designated M(2), are virtually the same as those of pyrite. The two species are therefore difficult to distinguish from one another. Values of the concentration of pyrite in coals and shales may be inflated if the pyrite concentration is measured by Mossbauer spectroscopy. Mossbauer spectra of the heat-treated illite samples reveal changes in iron distribution, principally at the 700 and 1000 °C levels, where there are found three and six different iron species respectively. These changes are accompanied by reduction of ferric to ferrous iron. This process should be integrated into any assessment of the iron chemistry which accompanies coal-conversion processes.

Migration of sulphur from organic to the inorganic phase under hydrodesulphurization conditions

Abstract Nonisothermal hydrodesulphurization of model organic sulphur compounds was carried out in a coal-like environment. The model sulphur compounds represented different types of carbon-sulphur bonds commonly encountered in coal. Similar experiments were also carried out in the presence of troilite (FeS) to investigate the possibility of sulphur migration from the organic compound to the iron sulphide. Results show that sulphur from organic compounds can be absorbed by troilite. Based on this observation it is suggested that during hydrodesulphurization it is possible to have migration of sulphur from the organic to the inorganic phase.

Correlation of natural gas content to iron species in the New Albany shale group

Abstract Mossbauer parameters were obtained for four Illinois Basin shales and their corresponding

Methods for detecting the mobility of trace elements during medium-temperature pyrolysis

Abstract The mobility (volatility) of trace elements in coal during pyrolysis has been studied for distances of up to 40 cm between the coal and the trace element collector, which was graphite or a baffled solvent trap. Nineteen elements not previously recorded as mobile were detected.

Carbon monoxide detection of chemisorbed oxygen in coal and other carbonaceous materials

The oxidation of carbon monoxide by mildly oxidized and devolatilized coal samples was studied thermogravimetrically. The oxidation was attributed to oxygen chemisorbed on inorganic components of the coals. The reaction of CO with pyrite producing carbonyl sulphide, OCS, accompanied the oxidation. A mechanism for CO oxidation is proposed in which active oxygen chemisorbed on the inorganic components of the coal directly oxidized CO to CO2, and facilitates the chemisorption of CO on the coal as carbonate. A factor, α = (1114) [1 − (WnWc)], was derived where Wn is the sample weight loss not attributed to OCS formation, and Wc is the estimated weight of evolved CO2. This quantity is proportional to the fraction of CO2 produced by the direct oxidation of CO, and was used to compare the coal samples studied. Samples of an Illinois No. 5 coal yielded average α values of 0.7 and those of an Illinois No. 6 coal yielded values of 0.6, indicating that in these cases, the majority of CO2 produced came from the direct oxidation of CO. The results obtained for the coal samples are compared with a selection of carbonaceous samples for which the proposed mechanism does not apply.