Microporous carbons, because of the narrow porosity, usually require 250°C, so it should be the maximum temperature in your case. If you are afraid of sintering the copper, you can use 200°C, it should be enough. Just use it overnight in secondary vacuum.

Alain

Hi Alain,

So time of 12 hrs each for soaking and degassing shall be enough?

Thanks!

Probably, but degassing should never be shorter than 12 h, and the dynamic vacuum has to be very good at the same time.

Alain

Alain

For all the samples it is same, degassing for 12 hrs, say for mesoporous TiO2 anatase phase? or 250° for 180 min is enough?

Pratibha

180 min is never enough, as it takes a very long time for gaseous molecules to find their way out of a narrow porosity, even under an excellent vacuum. Molecules can only diffuse, and there is a huge number of inefficient collisions with the pore walls and with the walls of the sample holder before the molecules can go irreversibly to the vacuum pump.

Start degassing in the evening before you leave the lab, and see how good (or not) is the vacuum when you are back in the morning the day after.

250°C is enough for anatase.

Alain

Sir

But what about auto adjustment for degassing? It sometimes finishes even before that (180min). i.e. when we adjust the time 180 min and say command backfill and test segment yes in completion state, it is autoadjusted and degassing is completed in its own time.

Pratibha

Dear Shikha

  I am agree with Dr Celzard. You can follow these steps.

Hi Alain and Niranjan!

Thanks for your response

Can I put my samples in microwave oven for 10 hours and then put in BET analyser for 2 hours for degassing?

Please, never put metallic or conducting bodies in a microwave oven: you'll destroy both the sample and the oven, producing dangerous electric arcs inside. You have no choice but heating them in a normal way but always under vacuum (otherwise you'll oxidize them as well). So you can never heat before and degass after. Degassing is done under vacuum, and heating helps considerably.

Alain

Aain

Can you answer my question? It will be helpful to me.

Pratibha