HPVA II High Pressure Volmetric Analyzer

HPVA II Reporting

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The HPVA II software uses a National Instruments data acquisition interface to communicate with the analyzer. The data acquired during analyses are written to files that are read by a macro written in Microsoft Excel. The macro uses the temperature and pressure data to obtain the correspond-ing compressibility factors from NIST REFPROP software to correct for the non-ideality of the high-pressure gases. Data reduction using the Excel macro provides reports as interactive spread-sheets which list the temperature and pressure data used for volume adsorbed calculations as well as excess isotherm, weight percentage, Langmuir theory, kinetic data plots, BET surface area, and total pore volume.  Link to Supplemental Reporting

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Two Molecular Sieves at 25 oC
Microporous Carbon at Various Temperatures
Zeolite 5A at Various Temperatures

 
S-III Microporous Carbon at Various Temperatures
 
 
Six Different Coal-Bed Samples at 30 oC
Four Different Shales at 25 oC

 
Various Materials at 30 K
 
 
Two Activated Carbons at 77 K
MOF (CuBTC) at oC

 

Cryostat 

For extensive hydrogen storage studies at high pressures and low temperatures, the HPVA II can be interfaced with a cryostat to control analysis temperatures down to 30 K with a stability of ± 0.003 K. The cryostat does not require liquid cryogens for operation; instead, it utilizes the Gifford-McMahon refrigeration cycle where pressurized helium is supplied from a compressor to produce cold temperatures. The HPVA II software communicates directly with the cryostat temperature controller allowing for precise temperature measurements recorded over the duration of the adsorption experiment. Generating hydrogen adsorption isotherms at multiple cryogenic temperatures presents researchers the advantage of more accurately calculating the isosteric heats of adsorption of hydrogen on their materials of study.