Adsorption Isotherms for CO (2), O, and CH4 on Porous Palladium

At 300 K and between 0 similar to 13.3 kPa, adsorption isotherms for O-2, CO, CH4 on porous palladium were measured by using PVT method in low-vacuum system. The results indicate that Adsorption isotherms for CO on Pd is identical with the type adsorption isotherms that the amount adsorbed of CO increases with increasing pressure(<2.6 kPa), but little additional CO adsorbs with pressure increasing(<13.3 kPa). Isotherm for adsorption of O-2 or CH4 has a different effect in contrast to CO, i.e. significant adsorption of O-2 even at low pressure (<100 Pa), and the isotherms doesn't saturate at higher pressure(<13.3 kPa), and the amount adsorbed of CH4 is little and increases slightly with equilibrium pressure rising sharply (<13.3 kPa). And isotherm for adsorption of CO or CH4 can been classified Longmuir adsorption type, and that of O-2 can been described by Longmuir adsorption model only when equilibrium pressure is less than 1.33 kPa.