http://www.nature.com/ncomms/journal/v4/n1/full/ncomms2359.html#methodshttp://www.nature.com/ncomms/journal/v4/n1/full/ncomms2359.html#methods

Dear  Christian weinberger

 The low-pressure CO2 and N2 adsorption–desorption isotherms for azo-COPs were measured at 263, 273, 298 and 323 K using a static volumetric system (ASAP 2020, Micromeritics Inc., USA). I did this to find the selective adsorption between the gas. For example

Dear Christian Weinberger

                                                Thanks for your reply. I recorded forN2 isotherm at 25 C up to one bar. Degass at 100 C for 5 hrs. The Same procedure was carried out for CO2, the results were fine. I have a problem with N2 alone.  But when I recorded at 0C the isotherm was fine. So, i could not understand where are the mistake  and the analyser have no idea about it. 

The surface area of the same was 307 cm3/g.

Dear manoranjan,

I guess the data you looking for is not physisorption, as physisorption has to be studied at boiling temperature of adsorbing gas. Adsorption of N2 is although considered physisorption there are materials where N2 is chemisorbed.

As we increase the pressure there is decrease in partial pressure of N2 observed in your case.Which should be reverse. It means N2 is no longer in available as gas to exert pressure!

Also 100 C is not a good evacuation temperature. Is relative pressure seen in graph more than one? 

I suggest you to perform the experiment by heating at higher temperature if sample is stable.

Nobody asked on which surface you did your adsorption. Friends, don,t forget N2 has nuclear quadruple moment and as in the case of PSA  can does surprises, especially at high pressure. 

Dear Christian Weinberger!

Let me to remind you that adsorption of N2 at room temperature is used for separation air by using zeolites or activated carbon- PSA at room temperature.

Best regards