Adsorption characteristic measuring apparatus

An adsorption characteristic measuring apparatus that supplies a predetermined adsorption gas to a sample accommodated in a sample tube to measure an adsorption isotherm, the apparatus comprising:

• a refrigerant container that is filled with a constant temperature refrigerant in which the sample tube is immersed;
• a sample tube fitting portion that is provided at an opening of the sample tube;
• an adsorption gas supply portion that supplies the adsorption gas;
• a gas-supply-portion fitting portion that is provided at a supply port of the adsorption gas supply portion;
• a pipe portion that is provided between the gas-supply-portion fitting portion and the sample tube fitting portion and includes a reference volume portion having an inner space of a predetermined reference volume, a plurality of pipes, and a plurality of on-off valves;
• an exhaust portion that is connected to the pipe portion through the on-off valves;
• a reference-volume-portion pressure gauge that detects a pressure value of the reference volume portion,
• a sample tube pressure gauge that detects an internal pressure of the sample tube;
• and
• a measurement controller that performs opening/closing control of the plurality of on-off valves according to predetermined steps and measures an adsorption isotherm based on the internal pressure value of the sample tube and the pressure value of the reference volume portion,
• wherein the measurement controller obtains a plurality of sets of measurement values (true equilibrium pressure value and true adsorption amount) to calculate the adsorption isotherm by including:
• a unit-time leak pressure value acquiring portion that acquires a unit-time leak pressure value which is a pressure increase value per a unit time of the internal pressure value of the sample tube caused by a non-adsorption gas leaking from the outside of the sample tube fitting portion into an inner space of the sample tube in a state where the sample tube is sealed after the inside of the sample tube is exhausted;
• a measured equilibrium pressure value acquiring portion that acquires a pressure value at which a temporal change of the internal pressure value of the sample tube assumes an equilibrium state when an adsorption gas present in the reference volume portion is supplied into the sample tube, the inside of which is exhausted, and the sample tube is in a closed state;
• a true equilibrium pressure value calculating portion that calculates a pressure value after correction of a real leak pressure value is performed on a measured equilibrium pressure value, as a true equilibrium pressure value, the real leak pressure value being obtained in such a manner that the unit-time leak pressure value is multiplied by a leak time;
• and
• a true adsorption amount calculating portion that calculates an adsorption amount of the adsorption gas on the sample under the true equilibrium pressure value based on the pressure value of the reference volume portion and the true equilibrium pressure value.