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Return to Abstracts of Literature 1500-1749
1621. JOCHUM, P. [Enrichment of the Methane Content of Technical Gases, and the Production of a Carbon Monoxide-Free Illuminating Gas.] Jour. Gas-beleucht., vol. 57, 1914, pp. 73-80, 103-111, 124-131, 149-151; Chem. Abs., vo. 8, 1914, p. 1660.
Previous attempts to form CH4 from the CO and H2 of illuminating gas by the catalytic action of Ni have met with difficulty, owing tot he poisonous effect of S compounds or the fouling of the catalyzer by tars or deposited C. The optimum conditions for the reaction are determined, using synthetic mixtures of CO and H2 in the ratios 1:1, 1:3, 1:5, these being the proportions named in the 3 most-important patents. The latter also approximates ordinary coal gas and is the subject of the patents of the Cedford process, the most nearly successful of all. The main reaction goes readily at low temperatures and CO2 also is reduced easily. But, with high concentrates of CO or high temperatures, the reaction 2CO=CO2+C makes its appearance. This is partly counteracted by C+2 H2=CH4. The experiments were carried out with Ni reduced from the nitrate on unglazed porcelain. The analyses of the final gas were calculated back and checked very closely with the original mixtures, showing the accuracy of manipulation and absence of serious side reactions. With 1:1 mixtures, the CH4 could not be carried above 40% and at this point much CO2 was formed from the second reaction above. With 1:3 mixtures, the yield was 50-65% and some CO2 was formed; but with 1:5, no trace of CO2 appeared, though the CH4 could not be raised above 35%. However, in this latter gas, the contraction owing to the reaction was less, so that the net yield of CH4 was greater than where the concentration of CH4 was higher. Most of these experiments were run at the rate of 8 cc./min. in a tube 16 mm. in diameter, though it was found that up to 200 cc./min. no CO2 appeared. The optimum temperature for 1:5 mixtures is 280°. With mixtures of C2H4 and H2 in the theoretical amounts for C2H4+H2=C2H6 no difficulty was met and a gas of 80% C2H6 with virtually no C2H2 could be obtained at 150°. As the temperature rose the reaction C2H6=CH4+H2+C appeared, and at 320° a gas of 90% CH4 with no H2 and only traces of C2H2 was obtained. This decomposition is at decidedly lower temperatures than noted by Sabatier, probably owing to a better catalyzer. With synthetic illuminating gas (9% CO, 50% H2, 38% CH4) no difficulty was found in preparing a gas of 85% CH4, no trace of CO, and less than 1% of CO2. This was at 300° and the velocity was increased to 90 cc./minute without CO appearing in the end products. With actual city gas, purified from S, after 24 hr. CO began to appear. This was due to tarry materials collecting on the catalyzer; for when the gas was passed through CO2 snow and ether on its way to the catalyzer, a gas of 85% CH4, wholly free from CO, and with only traces of CO2, was still obtained after 62 hr. Though this process as applied to commercial illuminating gas means a loss of heat (with CO:H2=1:5 a net loss of 14% and with illuminating gas a loss of 11%), the resulting gas has a much higher heating value/m.3 and as such is more valuable. The main disadvantage is the cost of purification by freezing, which will be partly offset by the benzene recovered. As a process for the manufacturing of CH4 as a material for chemical industries, it could hardly compete with natural gas. Reviews most important patents in this field.