Methods of selectively separating CO.sub.2 from a multicomponent gaseous stream

A method for selectively removing CO.sub.2 from a multicomponent gaseous stream to produce a CO.sub.2 depleted gaseous stream, said method comprising:

• preparing CO.sub.2 nucleated water by contacting CO.sub.2 gas with water in a nucleation reactor;
• contacting said multicomponent gaseous stream with said CO.sub.2 nucleated water in a CO.sub.2 hydrate formation reactor under conditions of selective CO.sub.2 clathrate formation, whereby CO.sub.2 is absorbed from said gaseous stream by said CO.sub.2 nucleated water and concomitantly fixed as CO.sub.2 clathrates upon said contacting, whereby a CO.sub.2 depleted gaseous stream and a CO.sub.2 clathrate slurry are produced;
• separating said CO.sub.2 depleted gaseous stream from said CO.sub.2 clathrate slurry;
• and
• heating said CO.sub.2 clathrate slurry in a manner sufficient to produce CO.sub.2 gas and CO.sub.2 nucleated water.

A method for selectively removing CO.sub.2 from a multicomponent gaseous stream to produce a CO.sub.2 depleted gaseous stream, said method comprising:

• preparing CO.sub.2 nucleated water by contacting CO.sub.2 gas with water in a nucleation reactor, wherein said CO.sub.2 nucleated water is prepared by combining recycled nucleated water with CO.sub.2 gas and make up water and said reactor is cooled with a cooling means comprising ammonia at a temperature of from 0 to 10.degree. C.;
• contacting said multicomponent gaseous stream with said CO.sub.2 nucleated water in a CO.sub.2 hydrate formation reactor under conditions of selective CO.sub.2 clathrate formation, wherein said contact is achieved by injecting said multicomponent gaseous stream into said reactor through 1 to 20 injectors, whereby CO.sub.2 is absorbed from said gaseous stream by said CO.sub.2 nucleated water and concomitantly fixed as CO.sub.2 clathrates upon said contacting, whereby a CO.sub.2 depleted gaseous stream and a CO.sub.2 clathrate slurry are produced;
• separating said CO.sub.2 depleted gaseous stream from said CO.sub.2 clathrate slurry;
• and
• decomposing said CO.sub.2 clathrate slurry in a heat exchanger in a manner sufficient to produce CO.sub.2 gas and CO.sub.2 nucleated water.