Process for the preparation of methane and/or ethane

A process for the preparation of methane and/or ethane, which comprises contacting as feed a C.sub.2-4 paraffin or a hydrocarbon mixture which consists of more than 75% C.sub.2-4 paraffins and which C.sub.2-4 paraffins have an average molar carbon number which is at least 0.5 higher than that of the C.sub.2.sup.- paraffin fraction of the product, at an elevated temperature of from 400.degree. to 800.degree. C., a pressure of above 10 to below 100 bar, and a space velocity of from 0.1 to 20 g.g.sup.-1.h.sup.-1 in a contact zone with a crystalline silicate as the catalyst, which silicate is characterized in that after 1 hour's calcining in air at 500.degree. C. it has the following properties:

• (a) thermally stable up to a temperature above 600.degree. C.,
• (b) an X-ray powder diffraction pattern showing, inter alia, the reflections give 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 meanings:
• VS=very strong;
• S=strong;
• M=moderate;
• W=weak;
• .theta.=angle according to Bragg.
• (c) after conversion of the silicate 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 ##EQU3## (d) the composition, expressed in moles of the oxides, is as follows:
• y.(1.0.+-.0.3)M.sub.n/.sbsb.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 y.gtoreq.0.01;
• and withdrawing a methane and ethane containing product from said catalyst zone.