Process for the preparation of an aromatic hydrocarbon mixture

Claim 1

A process for the preparation of an aromatic hydrocarbon mixture, which comprises contacting a feed comprising one or more olefins with two to four carbon atoms per molecule or aliphatic hydrocarbon mixtures, at least 20 wt.% of which consists of the said olefins, at a temperature of between 325° and 550° C. with a catalyst containing a crystalline metal silicate, which silicate has the following distinguishing features after calcination for one hour in air at 500° C.: (a) an X-ray powder diffraction pattern containing as strongest lines the four lines listed in Table A as follows, and TABLE A ______________________________________ d(Å) ______________________________________ 11.1 ± 0.1 10.0 ± 0.1 3.84 ± 0.07 3.72 ± 0.06 ______________________________________ (b) when the composition of the silicate is expressed in moles of the oxides, and wherein, apart from SiO 2 , one or more oxides of a trivalent metal (X) selected from aluminum, iron, gallium and boron are present, the SiO 2 /X 2 O 3 mol. ratio is between 25 and 400, that the reaction product from the first stage is separated into a C 4 - and a C 5 + fraction, that the C 4 - fraction is contacted in a second stage at a temperature of 450°-700° C. that is at least 50° C. higher than the temperature employed in the first stage with a catalyst that contains a crystalline gallium silicate, which silicate has the following distinguishing features after calcination for one hour in air at 500° C.: (a) an X-ray powder diffraction pattern than contains as strongest lines the four lines listed in Table A, and (b) when the composition of the silicate is expressed in moles of the oxides, the SiO 2 /Ga 2 O 3 mol. ratio is between 25 and 250, that the reaction product of the second stage is separated into a C 4 - fraction and a C 5 + fraction, that the separated C 5 + fractions are mixed and that, if the gallium silicate present in the second-stage catalyst has an SiO 2 /Ga 2 O 3 ratio of 100-250, the catalyst is subjected one or a number of times to a two-stage treatment ("redox treatment") comprising a first stage in which the catalyst is contacted for at least 15 minutes at a temperature of 350°-700° C. with a hydrogen-containing reducing gas, followed by a second stage in which the catalyst is contacted for at least 15 minutes at a temperature of 350°-700° C. with an oxygen-containing oxidizing gas.