Abstract: Production of cumene by alkylation of benzene with propylene on a solid phosphoric acid catalyst, using in a first step a plurality of catalyst beds in series and in a second step a single catalyst bed, using an overall benzene/propylene molar ratio of at least 5:1, continuously delivering the benzene to the first bed, continuously delivering a series of streams of liquid propylene respectively to the first bed and, in the form of a cold stream, between each pair of contiguous beds, and carrying out a partial recycle of reaction products of the second step as a cold stream between the first and the second step, and using a benzene/propylene molar ratio higher than 13:1 at the inlet of each bed of the first step, and higher than 25:1 at the inlet of the bed of the second step.

Abstract: Production of cumene by alkylation of benzene with propylene on a solid phosphoric acid catalyst, using a first step with a plurality of catalyst beds in series and a second step with a single catalyst bed, using an overall benzene/propylene molar ratio of at least 6:1, continuously delivering the benzene to the first bed, continuously delivering a series of streams of liquid propylene respectively to the first bed and, in the form of a cold stream, between each pair of contiguous beds, and using a benzene/propylene molar ratio higher than 16:1 at the inlet of each bed of the first step, and higher than 25:1 at the inlet of the bed of the second step.

Abstract: Phenol pitch obtained as a bottoms fraction in the distillation of phenol deriving from the acid hydrolysis of cumene hydroperoxide is treated to recover therefrom desired products consisting of phenol, alpha-methylstyrene, cumene and acetone, by introducing steam and the phenol pitch, into a reactor in a weight ratio of from 0.01:1 to 1:1, withdrawing from the top of said reactor a vapor phase comprising said desired products, withdrawing from the bottom of said reactor a liquid phase consisting essentially of compounds of higher boiling point than said desired products, and operating at a pressure of 4-12 Kg/cm.sup.2, at a temperature of 320.degree.-400.degree. C., as measured in the liquid phase, and with a residence time of 0.5-10 hours.