Experimental Study On The Adsorbents For The CO₂/CH₄ Mixture

The main object of the work was to find an excellent adsorbent to separate themixture of CO₂ and CH4. To get highly purified methane, a combinative action principleof absorbability method and pressure swing adsorption was performed, and at one timethe separation effect of CO₂/CH₄ on adsorbent with liquid film was measured. Based onthe breakthrough curve of the mixture of CO₂ and CH4, the separation coefficient wascalculated as the rule of selecting adsorbent. TEA is selected as the sorbent to modify thesurface of silica gel for its high boiling point, considering the stability of the adsorbentwith liquid film. The breakthrough curves of the mixture of CO₂ and CH4 on the silica gelwith four different concentrations of TEA were monitored through dynamic method, andthe separation effect could be analyzed through their separation coefficient. At the sametime, the desorption effect is monitored under the optimum concentration and differentpressures, when the methane was taken as regeneration gas. Then, at the optimumpressure the regenerative capacity of adsorbent was measured to obtain the stability of theadsorbent.From above experiment it was shown that the silica gel which surface was spreadwith 15% TEA has the best selectivity, which separation coefficient can reach 14 at2atm.In addition, the separetion coefficient drop when pressure rise. The regenerationexperiments were further undertaken under the same condition, and a agreement ofbreakthrough curves after regeneration was found, which show silica gel spreaded 15%TEA is very stable. Therefore, it could be showed the silica gel spread with 15% TEA wasan excellent adsorbent to separate the mixture of CO₂ and CH4.