Process for the preparation of methane and/or ethane

Claim 1

A process for the preparation of methane and/or ethane, which comprises contacting as feed a C 2-4 paraffin or a hydrocarbon mixture which consists of more than 75% C 2-4 paraffins and which C 2-4 paraffins have an average molar carbon number which is at least 0.5 higher than that of the C 2 - paraffin fraction of the product, at an elevated temperature of from 400° to 800° C., a pressure of above 10 to below 100 bar, and a space velocity of from 0.1 to 20 g.g -1 .h -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° C. it has the following properties: (a) thermally stable up to a temperature above 600° 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 θ 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; θ=angle according to Bragg. (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 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/ .sbsb.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 y≧0.01; and withdrawing a methane and ethane containing product from said catalyst zone.