3374. TERRES, E., PATSCHEKE, G., HOFMANN, H., KOVACS, S., AND LÍHR, O. [Formation of Water Gas and the Behavior of Brown-Coal and Bituminous-Coal Cokes and Semicokes in Water-Gas Generation.] Gas u. Wasserfach, vol. 77, 1934, pp. 585-587, 628-636, 650-655, 666-669, 681-684, 703-706; Chem. Abs., vol. 29, 1935, p. 577.
Cokes and semicokes from the bituminous coal Unser Fritz and from several brown coals were prepared at various temperatures 300░-1,200░ and gasified at slightly lower temperatures in N2 containing H2O vapor. Merck wood charcoal also was gasified. The water-gas analyses were used to calculate the extent of steam decomposition, CO:CO2 ratios, and the water gas and Boudouard equilibrium; similar calculations were made for the theoretical steam-C equilibrium at temperatures 400░-1,200░ with the N2 0-100% saturated with H2O. At 1,200░, the bituminous coal coke gave a steam decomposition, CO:CO2 ratios, and the C gasification distinctly lower than the corresponding equilibrium values, and lower than wood charcoal. The reactivity of the bituminous-coal cokes decreased with increasing carbonizing temperatures. The brown-coal cokes and semicokes reached no consistent gasification equilibrium. Steam decomposition increased with increasing gasification temperature and with decreasing saturation and lower rate of flow of the gasifying medium. The reactivity with steam of the carbonized product increased with carbonizing temperature up to 700░, decreasing at higher temperatures. This is attributed to a progressive uncovering of the C structure at the lower temperatures followed by the production of a coarser structure at higher temperatures. Steam decomposition is initially, more or less proportional to the time of contact, then increases more or less rapidly according to the reactivity of the material, and then at a lower rate, probably without reaching an equilibrium value in a reasonable time. Carbonized materials can be arranged in the following order with respect to increasing water gas formation and increasing reactivity: Graphite, lamp black, bituminous-coal coke and semicokes, wood charcoal, and brown-coal cokes and semicokes. The water gas equilibrium was approached in the gasification of wood charcoal and bituminous-coal cokes at about 600░ and attained above 750░. This equilibrium was obtained slowly in an empty porcelain tube at 600░. The brown-coal cokes and semicokes showed no regularity in attaining this equilibrium. The Boudouard equilibrium C+CO2=2 CO was not fulfilled in any of these experiments. By using the Ostwald gasification triangle, it was shown that the reaction of steam with bituminous-coal coke and wood charcoal was free from secondary reactions, but that the brown-coal semicokes results showed an excessive unexplained O2 action. The use of the gasification triangle showed that the results of Harries and of Gwosdz with wood charcoal and coke were free from secondary reaction effects, but that the results of Bunte and Giessen (abs. 407), on various cokes showed a surprising excess of H2. An attempt was made to correlate surface activity, as determined by the heat of wetting of several brown-coal cokes and semicokes, with reactivity, but there appeared to be no distinct relationship. The influence of carbonizing temperature, gasification temperature, steam content, and time of contact of the gasifying medium on the gasification of the coke S content was investigated. Various views as to the nature of the primary action of steam on C are contrasted. When the reaction of steam with carbonized materials does not follow the water gas equilibrium, the principal reaction is believed to be largely, if not entirely, C+H2O=CO+H2, as larger amounts of CO are formed than can be accounted for by the water gas equilibrium. 57 refs.