Cymenes as Xylene-substitutes by Catalytic Conversion of Indian Turpentine Over Supported Chromia and Platinum

Department of Chemical Engineering, A. C. College of Technology, Anna University, Madras-600 025

Division of Applied Science, Madras Institute of Technology, Anna University, Madras-600 044

Manuscript received 2 May 1988, accepted 18 February 1984

Dehydrogenation of the constituents of Indian turpentine, viz., 3-carene,\(\propto\).-pinene and\(\beta\)-pinene to\(\mathcal{p}\)- and \(\mathcal{m}\)-cymenes has been investigated over chromia-alumina, chromia-alumina-potassium oxide and platinum-alumina catalysts in the vapour phase. Weak acidic alumina impregnated with low percentage of chromium is very effective in the conversion of 3-carene to \(\mathcal{p}\)- and \(\mathcal{m}\)-cymenes. Platinum-alumina, unlike chromia-alumina, develops its catalytic activity in the lower temperature regions. The proportion of cymenes is always more from 3-carene than from pinenes. The total cymene content varies with the operation variables. The ratio of \(\mathcal{p}\)-cymene to \(\mathcal{m}\)-cymene (p/m) from 3-carene remains almost constant in the range of 1.5-2.0. lsokinetic relationship for the dehydrogenation of 3-carene over chromia-alumlna-potassium oxide has been arrived at with a correlation coefficient of 0.988 and a standard deviation of 1.49.