Abstract:

The natural gas purification technology through pressure swing adsorption (PSA) at low temperature was proposed based on the low temperature processing and the conventional PSA technology applied in liquefied natural gas storage and transport.Coconut shell activated carbon was used for the static adsorption of CO₂ and CH₄ component gas and the dynamic simulation of adsorption separation of binary mixed CO₂/CH₄  gas.At  -30~25 ℃,the static volumetric method was used to investigate adsorption behavior of CO₂ under the pressure from 1.2~2.5 MPa and that of CH₄ under the pressure from 0~4 MPa,respectively.The results showed that the adsorption capacity of coconut shell activated carbon for both CO₂ and CH₄ increased with the decrease of temperature.Under the pressure of 0.45 MPa,0.85 MPa and 1.85 MPa for the dynamic tests,it was found that the separation factor will continue to increase with the decreases of temperature or pressure for binary mixed CO₂/CH₄ gas;besides,it was found the effect of temperature is greater than the impact of pressure;furthermore,the dynamic adsorption capacity of CH₄ increases at first and then decreases within the range of experiment temperature.The research shows that coconut shell activated carbon for natural gas decarburization has broad application prospects.

Key words: natural gas, coconut shell activated carbon, adsorption capacity, separation factor