Gravimetric helium adsorption experiments

To measure binary coadsorption equilibria by tbe volumetric-gravimetric method one proceeds as follows A sorbent sample of 1 g - 3 g and appropriate counterweights, typically lead or silver balls, are placed to the buckets of the microbalance. Then the sorbent is activated by exposing it to helium gas at higher temperatures, i. e. 433 K for activated carbons, 673 K for zeolites and inorganic molecular sieves. After cooling down and evacuation (< 10 Pa) the adsorption chamber is prepared for an adsorption experiment. 

Methanol chemisorption experiments have also been carried out at atmospheric pressure in a specially adapted thermal gravimetric analyzer (TGA) microbalance coupled with a PC for temperature and weight monitoring [38]. The system allowed a controlled flow of high purity gases air for pretreatment, helium and a mixture of 2000 ppm methanol in helium for adsorption experiments. 

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