The dealkylation of alkyl aromatic hydrocarbons. II.-The dealkylation of coal tar naphthas

✍ Scribed by Betts, W. D. ;Popper, F. ;Silsby, R. I.

• Publisher: Wiley (John Wiley & Sons)
• Year: 2007
• Weight: 460 KB
• Volume: 7
• Category: Article
• ISSN: 0021-8871
• DOI: 10.1002/jctb.5010070904

✦ Synopsis

Abstract

The thermal dealkylation of toluene, xylene, vertical‐retort and coke‐oven naphthas has been studied at 100 atmospheres pressure in the presence of hydrogen at temperatures in the range 540–660°. The experiments with toluene were carried out to check the kinetics already proposed^1^ in this new experimental region. The rate constants, calculated on the basis of a 1·5‐order reaction from the results now obtained, were found to be lower than anticipated by extrapolation of the results obtained in the first part of this series. This discrepancy is discussed and results from two other sources have been used to calculate rate constants at intermediate and lower temperatures in an attempt to clarify the position. The experiments with the 5° xylole and the vertical‐retort naphtha show that it is possible to convert the polymethylbenzenes almost completely to benzene and toluene at temperatures in the region of 650°. The paraffinic materials in these feedstocks are cracked to gas. The formation of higher‐boiling materials can be limited by using high molar ratios of hydrogen to hydrocarbons. The experiments with the coke‐oven feedstocks show that these materials are very stable under the above experimental conditions. This stability is directly related to the low concentration of alkylated aromatic hydrocarbons which occur in these naphthas.