DE698498C - Process for the reduction of crude phenols - Google Patents

Description

Process for the reduction of crude phenols in wastewater treatment In the mines and coking plants there are considerable amounts of raw cresol, which are only used for . Part can be used. Attempts have long been made to convert raw cresol into more valuable ones Products, e.g. B. toluene to convert; especially catalytic hydrogenation shows promising results. The industrial exploitation of the previously known The process failed because of the high price and the sensitivity of the catalysts used as well as the low turnover rate. As for catalytic hydrogenation of the raw cresol, only coke or coal gas is considered for economic reasons, hitherto so-called poison-resistant catalysts had to be used, d. H. those through the sulfur compounds still present in the purified coke or luminous gas are not influenced in their effectiveness. As poison-resistant catalysts are known the oxides of molybdenum and tungsten. Molybdenum and tungsten catalysts are but expensive, sensitive to temperature and usually difficult to access after use regenerate; also is the rate of turnover achieved with these catalysts in the laboratory by all means inadequate in practice.

It has been found that all the disadvantages mentioned are avoided, if aluminum oxide is used instead of the conventional catalysts. For the production According to the invention, this catalyst is based on the chloride of the metal, since Commercial aluminum oxide has no or only slight catalytic properties owns. The chloride is expediently dissolved in a zo to x5% aqueous solution Carrier (pumice stone, chamotte, etc.) brought and by slowly heating water freed. The temperature may only be increased slowly and a certain maximum temperature do not exceed, otherwise the catalyst will be ineffective. A Maximum temperature of 8oo ° not exceeded. If no If more hydrogen chloride mist escapes, the catalyst is ready for use.

If a mixture of cresol vapor and coke gas is passed over the catalyst produced in this way at a temperature of about 47o to 500 ', the raw cresol is converted almost quantitatively into benzene hydrocarbons. It was found that the catalyst has poison-resistant properties, that is, its catalytic effect is not impaired by the sulfur compounds in the gas. Catalysts that have become ineffective can be completely regenerated by roasting at a higher temperature. It was also surprising that the hourly throughput compared to the molybdenum catalysts used earlier could be increased by up to about three times the amount otherwise customary. Up until now it was of the opinion that an aluminum oxide catalyst was inferior to a molybdenum oxide catalyst or at most could in a suitable form be equivalent to the molybdenum oxide catalyst in terms of effectiveness. Thus it could not be expected that the conversion would be increased considerably by using the aluminum oxide catalyst.

Example By a loaded with about zoo g molybdenum oxide catalyst A cresol vapor / coke gas mixture was passed into the reaction tube at 39o '. The throughput speed was 8 to 10 cm3 cresol per hour. Benzene hydrocarbons were obtained 66 per cent of theory. Implementation decreased as the throughput speed increased. Based per liter of catalyst volume, the throughput was 37 to 46 cm3 of cresol and 115 liters of coke gas.

The same amount of an aluminum oxide catalyst prepared by the process described above makes it possible to increase the conversion to 2.4 cm3 per hour at 00 'with the same yield. Based on one liter of catalyst volume, the throughput was iii cm3 of Kiesol and 278 liters of coke gas.

During a working period of 1q. Days could be slackening the catalytic properties of the catalyst cannot be observed. The procedure thus brings not only a considerable economic saving but also a considerable one technical progress.

Claims (1)

PATENT CLAIM: Process for the reduction of crude phenols, if necessary in a mixture with benzene hydrocarbons, by means of hydrogen-containing gases with ordinary Pressure and elevated temperature using aluminum oxide as a catalyst. characterized in that it is carried out in the presence of aluminum oxide, which from aluminum chloride applied in aqueous solution to a carrier Heating at a slowly increased temperature, which does not exceed 800 °, established has been.