TECHNOLOGY FOCUS - INORGANIC CHEMISTRY - Preferred Components: The adsorbent bed comprises zeolite adsorbent material comprising a framework structure selected from FER, MFI, BEA and/or DON; microporous adsorbent material selected from zeolites, AlPOs, SAPOs, MOFs, ZIFs and/or carbon; or is adsorbent material selected from cationic zeolites, amine-functionalized mesoporous materials, stannosilicates and/or carbon. The zeolite exhibits Si/Al ratio of least 500. The adsorbent bed has open flow channels throughout its entire length through which the natural gas stream flows; is a parallel channel contactor.    TECHNOLOGY FOCUS - ORGANIC CHEMISTRY - Preferred Method: The method further involves: g) externally cooling the adsorbent bed to a third temperature lower than the second temperature; and h) repressurizing the adsorbent bed to within 90% of the first pressure; retrieving from the product output end of the adsorbent bed a first product stream having at most 2 carbon atoms and having a higher mol.% of hydrocarbons having at least 2 carbon atoms than the natural gas stream. The first temperature is -195 to 300 (preferably 20-150) degrees C and the first pressure is 1-600 (preferably 2-200) bar. The second temperature is 10-300 (preferably 20-200) degrees C. The third temperature is -195 to 300 degrees C. In the method, a second purge gas stream is passed co-currently through the adsorption bed following depressurization step (c) and prior to heating step (d). The retrieving of the first product stream having at least 2 carbon atoms is performed concurrently with passing the second purge gas stream through the adsorption bed. In the method, reduction in pressure of step c) takes place in at least two steps, and where each step reduces the pressure of the adsorbent bed to a lower pressure than the next previous step. The external heating of step d) takes place co-current to the direction of the flow through the adsorbent bed; takes place counter-current to the direction of the flow through the adsorbent bed. The heating of step d) is performed under conditions sufficient to cause a thermal wave to travel along the adsorbent bed. The thermal wave travels co-current to the direction the gas mixture flow through the adsorbent bed. In the method, a T90 and T10 can be defined with respect to the second temperature and the first temperature such that a temperature differential of (T-T10) occurs over at most 50% of the length of the adsorbent bed. The thermal wave exhibits a maximum Peclet number, Pe, less than 10, where Pe=(U1asteriskL1)/a. In the method, less than 40% of the open pores of the adsorbent bed have diameters greater than 20 angstroms and less than 1 micron. The first pressure is at least 500 psig.U1=heat exchange fluid velocity and is 0.01-100 m/s;L1=characteristic distance over which heat is transported in a direction roughly perpendicular to fluid flow, and a represents an effective thermal diffusivity of the contactor over the distance L1 and is less than 0.1 meter.Preferred Components: The first methane product stream is greater than 95 (preferably greater than 98) mol.% methane. The first purge gas stream is greater than 95 mol.% methane. The first purge gas stream is selected from nitrogen and methane. The second purge gas stream comprises propane; greater than 95 (preferably greater than 98) mol.% propane. The second purge gas stream comprises propane. The first product stream having at least 2 carbon atoms comprises greater than 95 (preferably greater than 98) mol.% ethane. EXAMPLE - No suitable example given.