Process for the preparation of aromatic hydrocarbons and hydrogen from butane

A process for the preparation of aromatic hydrocarbons and hydrogen, which comprises contacting in a contact zone as feed a C.sub.4 paraffin or a hydrocarbon mixture which consists of more than 75% w C.sub.4- paraffins and more than 50% w C.sub.4 paraffins with a catalyst consisting essentially of a zinc-promoted crystalline silicate at a temperature of from 350.degree. to 700.degree. C., a space velocity of from 0.1 to 20 g.g.sup.-1.h.sup.-1 and at a pressure below 5 bar, which silicate is characterized as having the following properties after 1 hour's calcining in air at 500.degree. C.:

• (a) thermally stable up to a temperature above 600.degree. C.,
• (b) an X-ray powder diffraction pattern showing, inter alia, the reflections given in Table A.
• TABLE A ______________________________________ Radiation:
• Cu-K Wavelength 0.15418 nm 2 .theta. relative intensity ______________________________________ 7.8-8.2 S 8.7-9.1 M 11.8-12.1 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 VS = very strong;
• S = strong;
• M = moderate;
• W = weak;
• .theta. = angle according to Bragg's law,
• (c) after conversion of the silcate into the H-form and after evacuation at 2.times.10.sup.-9 bar and 400.degree. C. for 16 hours and measured at a hydrocarbon pressure of 8.times.10.sup.-2 bar and 100.degree. C., the adsorption of n-hexane is at least 0.8 mmol/g, the adsorption of 2,2-dimethylbutane at least 0.5 mmol/g and the ratio ##EQU4## (d) the composition, expressed in moles of the oxides, is as follows:
• y(1.0.+-.0.3)M.sub.n/2 O.y.Al.sub.2 O.sub.3.SiO.sub.2
• wherein M=H and/or alkali metal and/or alkaline-earth metal, n is the valency of M and 0.0065<y.ltoreq.0.0017;
• said catalyst containing 0.05 to 20% w zinc and withdrawing an aromatic hydrocarbon mixture and a hydrogen-containing gaseous mixture from said contact zone.