Surface characterization of porous solids and powder materials using flowing gas

A method for characterization of a porous solid or powder sample using flowing gas, the method comprising, by a controller:

• controlling mass flow of a carrier gas and an adsorptive gas to form a mixture having a target concentration of the adsorptive gas over the sample;
• cooling the sample;
• determining adsorptive gas concentration based on signals from a detector disposed downstream of the sample;
• automatically repeating the controlling and determining steps for a plurality of different target concentrations;
• and
• generating an isotherm for the sample based on the adsorptive gas concentration for the plurality of different target concentrations wherein controlling the mass flow of the carrier gas and the adsorptive gas comprises adjusting the mass flow of the carrier gas and the adsorptive gas to form a mixture having a target concentration that maintains a constant concentration difference between the concentration of the adsorptive gas flowing over the sample and the adsorptive gas concentration determined by the detector disposed downstream of the sample.

A method for characterization of a porous solid or powder sample using flowing gas, the method comprising:

• controlling, by at least one associated controller, mass flow of a carrier gas and mass flow of an adsorptive gas through a mixer to form a mixture and delivering the mixture having a target concentration of the adsorptive gas to a sample cell containing a predetermined amount of the sample;
• selectively cooling the sample cell to a first predetermined temperature;
• measuring concentration of the adsorptive gas downstream of the sample cell;
• and
• repeating the steps of controlling, selectively cooling, and measuring for a plurality of target concentrations of the adsorptive gas to characterize the sample.

A method for characterization of a porous solid or powder sample using flowing gas, the method comprising:

• controlling, by at least one associated controller, mass flow of a carrier gas and mass flow of an adsorptive gas through a mixer to form a mixture and delivering the mixture having a target concentration of the adsorptive gas to a sample cell containing a predetermined amount of the sample;
• selectively cooling the sample cell to a first predetermined temperature;
• measuring concentration of the adsorptive gas downstream of the sample cell;
• and
• repeating the steps of controlling, selectively cooling, and measuring for a plurality of target concentrations of the adsorptive gas to characterize the sample, wherein measuring concentration of the adsorptive gas downstream of the sample cell comprises:
• positioning a concentration detector having a housing and a filament within the housing downstream of the sample cell;
• heating the housing to a first setpoint temperature;
• and
• heating the filament to a second setpoint temperature higher than the first setpoint temperature.

A method for surface characterization of a porous solid or powder sample using flowing gas, the method comprising, by at least one programmable controller:

• controlling a first mass flow controller to deliver a controllable mass flow of a carrier gas;
• controlling a second mass flow controller to deliver a controllable mass flow of an adsorptive gas;
• mixing the carrier gas and adsorptive gas from the first and second mass flow controllers and delivering an associated mixture to at least a first measurement channel containing a sample cell having a predetermined amount of the sample;
• measuring concentration of the adsorptive gas downstream of the sample cell;
• and
• varying a target concentration of the adsorptive gas in the mixture delivered to the sample cell to determine an amount of the adsorptive gas adsorbed and desorbed by the sample for each target concentration to provide surface characterization of the sample.

A method for surface characterization of a porous solid or powder sample using flowing gas, the method comprising, by at least one programmable controller:

• controlling a first mass flow controller to deliver a controllable mass flow of a carrier gas;
• controlling a second mass flow controller to deliver a controllable mass flow of an adsorptive gas;
• mixing the carrier gas and adsorptive gas from the first and second mass flow controllers and delivering an associated mixture to at least a first measurement channel containing a sample cell having a predetermined amount of the sample;
• measuring concentration of the adsorptive gas downstream of the sample cell;
• and
• varying a target concentration of the adsorptive gas in the mixture delivered to the sample cell to determine an amount of the adsorptive gas adsorbed and desorbed by the sample for each target concentration to provide surface characterization of the sample, wherein measuring concentration of the adsorptive gas in the mixture comprises:
• flowing the mixture through a detector housing containing a filament;
• controlling temperature of the detector housing to a first temperature;
• and
• controlling temperature of the filament to a second temperature above the first temperature.