The use of biogas as an environmentally friendly fuel is limited by the presence of CO2 and water vapor as
impurities. Therefore, biogas purification for CO2 and water vapor removal is very important step during biogas
application. This paper presents a process for biogas purification by means of adsorption using either modified
or unmodified activated carbon as an adsorbent. The modification was performed by passing a pure ammonia
gas into activated carbon in a quartz reactor. The results showed that the adsorption process using modified
activated carbon decreases CO2 content in biogas up to 67.5% whereas for unmodified activated carbon was of
43%. Further, the modification increased CO2 adsorption capacity from ~28 to ~38 mg CO2/g adsorbent. The
increase in feed temperature decreases CO2 adsorption capacity.