2668.     ---------------.  [PICHLER, H.]  [Effect of Pressure on the Conversion of Water Gas.]  Brennstoff-Chem., vol. 12, 1931, p. 235.

        Paper presented at the meeting of the Verein Deutscher Chemiker in Vienna, May 1931.  Increased pressure hinders the gasification of carbonaceous substances with steam, owing to the masking of the surface by inert gases.  If this inactivity is prevented by means of increased temperature or by the addition of alkali, a secondary formation of hydrocarbons occurs through the action of the nascent H₂ on the C present.  Increased pressure in the catalytic hydrogenation of CO favors the deposit of high-molecular products on the catalyst.  Thus the catalyst activity deteriorates much faster than at 1 atm. pressure.  At higher pressures acid-containing products take the place of the hydrocarbons.  Diminished pressure is unfavorable for the formation of hydrocarbons since for the same amount of conversion larger amounts of catalyst are necessary.  The nature and the speed of CH₄ cracking with CO₂ or steam is strongly influenced by pressure.  At 1/100 atm. and 500°-600° all of the CH₄ is converted into CO and H₂, whereas at atmospheric pressure a temperature of 900°-1,000° is required.  The speed of reaction increases in proportion to the diminution in pressure.