Georgina P. Hum

Conversion of bituminous coal in COH2O systems: 2. pH Dependence

Under COH2O systems at initial pH values s> 12.6, an Illinois No. 6 coal, PSOC-26, was converted to a fully pyridine-soluble product, with benzene and hexane solubilities of 50% and 18%, respectively. The product gases were H2 and CO2. However, the expected H2CO2 ratio of 1.0 based on the water gas shift reaction was not observed, but the deficit in hydrogen was found in the increased hydrogen content of the coal product. 95% coal carbon recovery and good hydrogen balances were obtained, and the coal products were found to be very similar to those from conventional tetralin systems. The results suggest an efficient base-catalysed process, and that COH2O systems are useful for coal studies.

Conversion of bituminous coal in COH2O systems: 3. Soluble metal catalysis

The oxyanions of the highest oxidation states of several transition metals, including W, Mo, Cr and Mn, were found to catalyse the liquefaction of Illinois No. 6 coal in COH2O systems at 400°C. Unlike the high pH (s> 12) required in the base-catalysed system, the effective range for these metal-mediated conversions extend down to pH < 5.0. The benzene-soluble product was found to have a higher HC ratio than the starting coal, and the metals were reduced to water-insoluble, lower oxidation states during conversion. A chain scheme is suggested as an explanation for the data.

Supercritical water/CO liquefaction and a model for coal conversion

Abstract Studies of Illinois No. 6 coal in CO/water at 400°C over a range of conversions to toluene-soluble (TS) products show product yields in D2O consistently superior to those in H2O, the yields leveling off respectively at 60% and 50%. These findings are compelling toward a conversion scheme in which coal is partitioned in parallel, competitive steps to TS and toluene insoluble (TI) fractions, with the TS/TI ratio determined by the reduction potential of the system. Conversion is thus limited by the kinetics of conversion rather than by coal structure, this limitation applying to conversion generally, including conventional donor conversions. The CO/water system has been successfully modeled with a numerical simulation scheme on a microcomputer, the model showing that the key limiting feature of the CO/water system is irreversible consumption of OH− by CO2. The major source of CO2 is the water gas shift reaction, which operates in parallel to the conversion chemistry.

Regular coal structure and conversion severity

In two separate coal conversion studies, one dealing with CO-water conversions of Illinois No. 6 coal, and the other with H2S addition to conventional tetralin conversions of the lower-rank Wyodak 2, data have been collected over a range of conversion levels. For both studies the degrees of conversion were increased by increasing the reducing power of the medium, while the conversion temperature was kept constant at 400 °C for all runs. The conversion levels for the CO-water runs ranged from 29 to 60%, while the tetralin-H2S runs yielded conversions from 44 to 67%. Sequential elution solvent chromatography and field ionization mass spectrometry were used for analyses of toluene-soluble fractions from the CO-water runs and THF-soluble fractions from the H2S-tetralin runs, respectively. The analyses showed that the fraction compositions remained constant with increasing degrees of conversion. This finding suggests that there may be some gross regularity in the structure of coal. Moreover, the results here are in contrast to work reported earlier, in which increased conversion levels, reached through greater conversion temperatures, yielded products with successively increased condensation and aromatization. It is thus suggested that severity be considered in terms of two components. Thermal severity reflects the temperature/time component of conversion chemistry, and derives from simple Arrhenius behaviour of competing reactions, while reduction severity reflects only on the reducing power of the system.

Synthesis of polynaphthoquinone

Abstract The synthesis of polynaphthoquinone in nitric acid was found to require N(III) catalysis.

Catalysis of aromatic nitration by the lower oxides of nitrogen

In the absence of nitrous acid traps, the nitration of phenol in 56·2% sulphuric acid displays autocatalytic behaviour; on the other hand, the isomer ratio of the products is inconsistent with the commonly accepted prior nitrosation scheme, and some other route for the promotion of nitration must be operative.