The carbon molecular sieve was adopted as adsorbent for biogas upgrading

and the morphologies of carbon molecular sieve were examined by scanning electron microscopy while the pore-size distribution was characterized by CO2 adsorption at 273.15 K. With the volume method

the adsorption isotherms of carbon dioxide and methane on carbon molecular sieve were measured at 283.15

303.15

and 323.15 K and at pressure up to 0.5 MPa

while the diffusion coefficient of carbon dioxide and methane on carbon molecular sieve were also determined. The breakthrough experiments were implemented on single fixed bed

and the effects of adsorption pressure and feed flow rate on the breakthrough curve of CO2 were explored. Two-bed-six-step vacuum pressure swing adsorption (VPSA) process was carry out with the adsorption pressure of 0.3 MPa and the feed flow rate of 4 L·min-1. In addition

the effects of adsorption step time and product flush ratio on separation performances were also investigated. The experimental results show that the purity of methane could be achieved to 98% with a recovery of 82% when adsorption time was set to be 140 s with a product flush ratio of 0.05.