Methods for manufacturing olefins from lower alkans by oxidative dehydrogenation

A method for producing ethylene and/or propylene from at least one lower alkane by oxidative dehydrogenation, which comprises:

• (1) supplying at least one lower alkane;
• (2) providing a source of oxygen;
• (3) converting a portion of the lower alkane by an oxidative dehydrogenation reaction process that utilizes a rare earth oxycarbonate catalyst, to produce unconverted lower alkane containing at least ethylene and/or propylene, at least one alkane byproduct and/or at least one higher olefin, and water, wherein the reaction pressure is at least about 75 psi and olefin and alkane byproduct are formed from the lower alkane with a combined selectivity of at least about 40% and a mole ratio of olefin to alkane byproduct of at least about 1/1;
• (4) removing water from the unconverted lower alkane;
• (5) recovering ethylene and/or propylene from the unconverted lower alkane by using an aqueous complexation absorption separation that utilizes at least one complexation agent containing a silver (I) ion to selectively remove ethylene and/or propylene from higher olefins and non-olefins and which is not a membrane separation;
• and
• (6) recycling after steps (4) and (5) a majority of the unconverted lower alkane which contains the at least one alkane byproduct and/or higher olefin to the oxidative dehydrogenation reaction process of step (3).

A method for producing olefins from at least one lower alkane by oxidative dehydrogenation, wherein recycling of unconverted lower alkane containing reaction byproducts is reduced or eliminated, which comprises:

• (1) supplying at least one lower alkane;
• (2) providing a source of oxygen;
• (3) converting a portion of the lower alkane by an oxidative dehydrogenation reaction process that utilizes a catalyst, wherein the reaction pressure is at least about 50 psi, to produce unconverted lower alkane containing at least one olefin product, at least one combustible byproduct, and water;
• (4) removing water from the unconverted methane;
• (5) recovering the at least one olefin product from the unconverted lower alkane by using a complexation separation that utilizes at least one complexation agent to selectively remove olefins from non-olefins and which is not a membrane separation;
• and
• (6) adding after steps (4) and (5) a majority of the unconverted lower alkane which contains the at least one combustible byproduct to a methane gas transport system.