A process for converting methane to ethane and ethylene through oxidative
coupling of methane and carbon conservation has been developed. The
process begins by contacting methane and an oxygen-containing stream with
an oxidative coupling catalyst that is capable of reacting with carbon
oxides to form a solid carbonate compound in an oxidative coupling reactor
to produce an effluent containing methane, ethane, and ethylene. The solid
carbonate compounds are thermally decomposed to the oxidative coupling
catalyst by reaction with hot hydrogen. The oxidative coupling catalyst is
then available for reuse and a stream containing hydrogen and carbon oxide
by-products are produced. The stream containing hydrogen and carbon oxide
by-products is contacted with a methanation catalyst in a methanation
reactor to produce a stream containing methane and water. The methane is
separated, dried, and recycled to the oxidative coupling reactor.
Alternatively methane and an oxygen-containing stream may be contacted
with an oxidative coupling catalyst in an oxidative coupling reactor to
produce an effluent containing methane, ethane, ethylene and carbon
oxides. The effluent is passed to an adsorption zone containing an
adsorbent capable of selectively adsorbing the carbon oxides. The carbon
oxides are desorbed from the adsorbent using hot hydrogen to generate a
stream containing hydrogen and carbon oxides which is then contacted with
a methanation catalyst in a methanation reactor to produce a stream
containing methane and water. The methane is separated, dried, and
recycled to the oxidative coupling reactor.