Production of p-Xylene from Xylene Mixture by Recycle Process (Part II) The Relation between the Composition of the Feed Stock and the Rate of Conversion in the Isomerization Reaction

• Published in: Journal of The Japan Petroleum Institute Vol. 3; no. 12; pp. 988 - 995
• Main Authors: Amemiya, Tozo, Tsunetomi, Eiichi, Nakamura, Etsuro, Nakazawa, Takao, Shimizu, Masashi, Chiba, Hiroo
• Format: Journal Article
• Language: English
• Published: The Japan Petroleum Institute 1960
• ISSN: 0582-4664
• DOI: 10.1627/jpi1958.3.988

The kinetics of the isomerization of xylene mixture, which was accompanied by the disproportionation of xylene and the cracking of ethyl benzene, and the effect of ethyl benzene concentration in xylene mixture on the side reaction products have been studied with silica-alumina catalyst in the presence of steam at the temperatures of 500-530°C. The results obtained were summarized as follows: i) As far as the change of relative ratio of xylene isomers in the feed stock was in such a range as p:m:o=6-10:60-70:20-30 (mole %), the xylene fraction of the isomerized oil had the composition almost equal to the thermodynamical isomerization equilibrium, independent of the concentration of ethyl benzene both in the feed stock and the isomerized oil. ii) The rates of decompositions (side-reactions) of xylene and ethyl benzene were dependent of the reaction temperature and their concentrations in the feed stock. 500°C XD=0.0338XF2/(1+0.0338XF), ED=0.0772EF 515°C XD=0.0431XF2/(1+0.0431XF), ED=0.1106EF 530°C XD=0.0548XF2/(1+0.0548XF), ED=0.1333EF where XD: the rate of decomposition of xylene. XF: the concentration of xylene in the feed stock. ED: the rate of decomposition of ethyl benzene. EF: the concentration of ethyl benzene in the feed stock. iii) Presences of H2, CO2 and CO were always observed in traces, accompanied by a few percents of C3+C3' and C4+C4' hydrocarbons in the produced gas. The presences of paraffins and olefins of low b. p. were confirmed in the produced oil, and substances of high b. p. were also suggested to be present in the product.