Apparatus and method for adsorption and desorption studies, particularly for characterization of catalysts

Method for measuring the amount of gas adsorbed by a sample, comprising the steps of:

• disposing said sample in a first sample chamber of known volume;
• measuring the pressure of gas within said first chamber;
• measuring the pressure of gas within a second chamber of known volume;
• creating a flow path between said first sample chamber and said second chamber through a flow restrictor having an orifice therein sized such that the rate of gas flow therethrough is less than the equilibrium rate of adsorption/desorption of gas with respect to said sample;
• monitoring the changes in gas pressure in said chambers as gas flows through said flow path from said second chamber into said sample chamber and is adsorbed by said sample;
• and
• determining the amount of gas adsorbed by said sample as a function of the changes in pressure in said first and second chambers.

Method for measuring the amount of gas desorbed from a sample, comprising the steps of:

• disposing a sample having a quantity of gas adsorbed thereon in a sample chamber of known volume;
• measuring the pressure of gas within said sample chamber;
• measuring the pressure of gas within a second chamber of known volume evacuated relative to said sample chamber;
• creating a flow path between said sample and second chambers through a flow restrictor having an orifice sized such that the rate of flow of said gas from said sample chamber to said second chamber is less than the equilibrium rate of adsorption/desorption of gas with respect to said sample;
• monitoring the changes in pressure in said chambers as gas is desorbed from said sample and flows from said sample chamber into said second chamber;
• and
• determining the volume of gas desorbed from said sample as a function of changes in pressure in said chambers.

Method for performing adsorption studies at constant pressure, comprising the steps of;

• disposing a sample in a first chamber of known volume;
• measuring the pressure of gas within said first chamber;
• measuring the pressure of gas within a second chamber of known volume;
• creating a controllable gas flow path between said first chamber and said second chamber through a controllable flow restrictor having a variable orifice therein;
• monitoring the change in gas pressure in said second chamber as a function of time;
• monitoring the change in gas pressure in said first chamber as a function of time;
• controlling the orifice of said flow restrictor responsive to said measurements of the pressure in said first chamber such that the pressure in said first chamber remains substantially constant over time;
• and
• determining the amount of gas adsorbed by said sample at any given time as a function of the pressures in said first and second chambers.

Method for performing desorption studies at constant pressure, comprising the steps of:

• disposing a sample having a quantity of gas adsorbed thereon in a first chamber of known volume;
• measuring the pressure of gas within said first chamber;
• measuring the pressure of gas within a second chamber of known volume;
• creating a controllable gas flow path between said first sample chamber and said second chamber through a controllable flow restrictor having a variable orifice therein;
• monitoring the change in gas pressure in said second chamber as a function of time;
• monitoring the change in gas pressure in said first chamber as a function of time;
• controlling the orifice of said flow restrictor responsive to said measurements of the pressure in said first chamber such that the pressure in said first chamber remains substantially constant over time;
• and
• determining the amount of gas desorbed by said sample at any given time as a function of the pressures in said first and second chambers.

Apparatus for measuring the amount of gas desorbed by a sample, comprising:

• a first chamber of known volume;
• means for accurately monitoring the pressure of gas within said first chamber;
• a sample chamber of known volume;
• means for accurately monitoring the pressure of gas within said sample chamber;
• flow restrictor means connected between said first chamber and said sample chamber;
• and
• means connecting said first chamber, said flow restrictor means and said sample chamber for gas flow therebetween.

Apparatus for performance of adsorption and desorption experiments, comprising:

• sample chamber means for receiving a sample of material;
• a chamber of known volume for receiving a gas to be employed in said adsorption and desorption experiments;
• pressure transducer means connected to each of said sample chamber means and said chamber of known volume, to monitor the pressures therein;
• and
• a flow restrictor connected between said sample chamber means and said chamber of known volume, for limiting the rate of flow of gas therebetween.