Catalytic activity and product distribution in the cracking of C6-C8 alkenes on the ammonium salt of 12-tungstophosphoric acid

The cracking of C₆-C₈ alkenes has been studied on the ammonium salt of 12-tungstophosphoric acid ( NH₄PW ). The products range from C₃ hydrocarbons to aromatics, the latter appearing in amounts up to 30% of the products. The primary products from the alkenes provide strong evidence that condensation processes are strongly favoured on these catalysts. The cracking ability of the catalyst decreases rapidly with time on stream but attains a steady state after approximately three hours. The activity of the catalyst is shown to be dependent on the source of the ammonium ion employed in the preparation of the salt with the activity of NH₄PW for hezene cracking decreasing in the order NH₄Cl > NH₄NO₃ > (NH₄)₂CO₃ > (NH₄)₂SO₄. The cracking activity of NH₄PW for the C₆-C₈ alkenes decreases in the order: octenes > heptenes > hexenes.