Process for the preparation of aromatic hydrocarbon mixture

Claim 1

A process for the preparation of an aromatic hydrocarbon mixture, which comprises contacting as feed a C 4- monoolefin or a hydrocarbon mixture which consists of more than 75%w C 4- monoolefins, at temperature in the range from 350° to 550° C. and a pressure in the range from 3 to 20 bar and a space velocity from 1 to 20 bar and a space velocity from 1 to 20 g.g -1 h -1 in a contact zone with a catalyst consisting essentially of a crystalline silicate, which silicate is characterized by having the following properties after 1 hour's calcining in air at 500° C.: (a) thermally stable up to a temperature above 600° C., (b) an X-ray powder diffraction pattern showing, inter alia, the reflections given in Table A: TABLE A ______________________________________ Radiation: Cu--Kα Wavelength 0.15148 nm 2θ relative intensity ______________________________________ 7.8-8.2 S 8.7-9.1 M 11.08-12.1 W 12.4-12.7 W 14.6-14.9 W 15.4-15.7 W 15.8-16.1 W 17.6-17.9 W 19.2-19.5 W 20.2-20.6 W 20.7-21.1 W 23.1-23.4 VS 23.8-24.1 VS 24.2-24.8 S 29.7-30.1 M ______________________________________ wherein the letters used have the following meanings: VS=very strong; S=strong; M=moderate; W=weak; θangle according to Bragg's law, (c) after conversion of the silicate into the H-form and after evacuation at 2×10 -9 bar and 400° C. for 16 hours and measured at a hydrocarbon pressure of 8×10 -2 bar and 100° C., the adsorption of n-hexane is at least 0.8 mmol/g, the adsorption of 2,2-dimethylbutane is at least 0.5 mmol/g and the ratio ##EQU3## (d) the composition expressed in moles of the oxides is as follows: y.(1.0±0.3)M n/2 O.y.Al 2 O 3 .SiO 2 , wherein M=H and/or alkali metal and/or alkaline-earth metal, n is the valency of M and 0.0075 ≧y≧0.0030, and (e) an average crystallite size (d)≦500 nm, and withdrawing an aromatic hydrocarbon mixture product from said contact zone.