TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Composition: The carrier gas comprises nitrogen, helium or argon. The reaction zone includes catalyst chosen from samarium oxide, magnesium oxide or strontium oxide. The separation zone includes activated charcoal as adsorbent.Preferred Condition: The reaction zone is maintained at 550-1100 degrees C, and separation zone is maintained at 0-200 degrees C. The feed gas is supplied to reaction zone inlet port such that methane to oxygen ratio entering the reaction zone is 10:1-100:1. Carrier gas is supplied at 100 ml/min, feed gas is initially supplied at 18 ml/min and supplied at 1.7 ml/min during purging of compartment (A) with carrier gas.Preferred Process: Unreacted feed gas and carrier gas transport, product recovery, purging of compartment (A) with carrier gas and switching of feed, carrier gas are repeated at time intervals such that product recovery from compartment (A) and purging of compartment (A) are completed before switching of feed gas supply to reaction zone inlet port of compartment (A) to start with next cycle.    TECHNOLOGY FOCUS - MECHANICAL ENGINEERING - Preferred Structure: The compartment comprises inlet and outlet port which define flow path between. The flow path is interposed with catalyst and adsorbent mixture. SPECIFIC COMPOUNDS - The feed gas is methane and oxygen. The product is ethylene or ethane.    EXAMPLE - Simulated and continuous counter current moving bed chromatographic reactors comprising reaction zone consisting of quartz tube with samarium oxide powder, separation zone consisting of aluminum separation column packed with activated charcoal, separation column divided into long upstream and downstream sections, and connecting line having 3-way computer-operated celluloid valve which permits ethane and ethylene passage was used. The apparatus was initially fed with 18 ml/min of 50:1 methane-air mixture and 100 ml/min of nitrogen carrier gas. Succeeding compartment was then fed with 100 ml/min of carrier gas, and ethane, ethylene were recovered from final compartment. The product obtained were analyzed by automatic sampling analytical gas chromatography. The selectivity and conversion of ethane and ethylene, were found to be 78 % and 65 % at 775 degrees C, respectively. The apparatus was found to rapidly separate oxidizable ethylene and ethane, from oxygen and methane between each reactor-separator compartment.