The paper was read by Prof. EVGRAF LEBEDEV, in the absence of the author, Prof. KAZANSKTI.
After the presentation of the paper the Chairman opened up the discussion: CHAIRMAN'S QUESTION: You have investigated n-hexane and n-heptane in your paper. It is well known that n-octane is used in a similar way, resulting in mixtures of xylenes. Have you considered this reaction, or have you considered further research in this direction? A.-Mr. LEBEDEV: The dehydrocyclization of noctane is also investigated at least in two Russian institutes, at Moscow and Grozny. This work will be published later.
CHAIRMANS QUESTION: British investigators have used temperatures in the order of magnitude of 480°C. You have used temperatures above 500°C.
Can this be lowered in order to decrease side reactions ? A.-Mr. LEBEDEV: It is true that at elevated temperatures around 500°–600°C, side reactions will greatly increase. However, for economical reasons it is necessary to use temperatures above 500°C. For this reason we have used temperatures of 500 to 530°C.
Q.-Mr. V. HAENSEL: The author indicates that methylcyclopentane is an undesirable component of the hexane feed for conversion to benzene. Does this mean that methylcyclopentane or methylcyclopentene is not an intermediate in the dehydrocyclization mechanism ? A.-Mr. LEBEDEV: We have not made a thorough investigation of the actual mechanism, but we are certain that hexene, hexadiene and hexatriene are intermediates before cyclization actually takes place.
Hence, we would say that the first steps are reactions of dehydrogenation before cyclization occurs. The reaction is now in the stage of pilot plant experiments.
A plant will be built to produce from 10,000 to 20,000 tons per year.
Q.-Mr. THOMAS: You showed a figure on the dehydrocyclization of n-heptane in which Cr+6 was being reduced in the early part of the cycle and water was liberated through the rest of the cycle. Was Cr+6 reduction continuing ? Or was the water coming from the alumina? Is this water liberated as part of the process, i.e. part of the mechanism? The Chairman added a few remarks in reply: In the paper it was clearly stated that Cr+6 is reduced to some lower valency. I would say that only a change of the Cr catalyst, and not of the alumina, is responsible for the mechanism.
A.-Mr. LEBEDEV: I do not want to exclude the influence of alumina. This question is being investigated in Grozny and results will be published later.
Adiabatic oxidative dehyrogenation of n-butenes to butadiene Dr. ALEXANDER read his paper, mentioned in the Technical Program under the name of Mr. J. FIRKO et al.
CHAIRMAN'S QUESTION: You used moderately elevated pressures in carrying ou
