Article: Nitrogen Adsorption On Lithium Exchanged X Zeolite (Li-X) At Multiple Temperatures Using The ASAP 2050

By Reid Davis

When gas physically adsorbs onto a sample, temperature plays a very significant role in the amount of gas that the sample is able to adsorb. Performing analyses on a sample at multiple temperatures allows the correlation between temperature and adsorbance to be seen. Zeolite Li-X (lithium exchanged X Zeolite) is a very good sample for the purpose of temperature-controlled analyses as it is highly dependent on temperature. Useful information can be extracted from the adsorption data at multiple temperatures; for example, finding a temperature which maximizes efficiency of adsorption on a large scale. Heat of adsorption data can also be extracted. The heat of adsorption is the amount of energy that is released when the adsorbate adsorbs onto the sample. The ASAP 2050 software includes a heat of adsorption report to allow easy calculation of the data. Heat of adsorption reports require at least two separate isotherms at different temperatures over the same pressure range to report accurate and repeatable results. The gas compressibility factor can be changed based upon the temperature and the thermochemical properties of the gas. The compressibility factor relates to the behavior of the gas at certain temperatures when compared to an ideal gas. Changes in the compressibility factor over a small temperature range are usually small, but have a noticeable impact on the adsorption data; therefore they cannot be ignored.