Future Problems
Adsorption of fluid at above-critical temperatures and elevated pressures is a field growing importance in both science and engineering. It is the physicochemical basis of many engineering processes and potential industrial applications. For example, separation or purification of light hydrocarbons, storage of fuel gases in microporous solids, adsorption from supercritical gases in extraction processes and chromatography. Besides, knowledge of gas/solid interface phenomenon at high pressures is fundamental to heterogeneous catalysis. However, the limited number of reliable high-pressure adsorption data hampered the progress of the theoretical study.
At least two problems have to be solved before a consistent system of theories for supercritical adsorption becomes sophisticated: first, how to set up a thermodynamically standard state for the supercritical adsorbed phase, so that the adsorption potential for supercritical adsorption can be evaluated? Second, how to determine the total amount in the adsorbed phase based on experimentally measured equilibrium data. Determination of the absolute adsorption is needed for establishing thermodynamic theory because as a reflection of statistical behavior of molecules, thermodynamic rules must rely on the total, not part of, material confined in the system studied.
From recent studies of supercritical adsorption, there seems to be an end in the high-pressure direction for supercritical adsorption. However, adsorbed-phase density is the decisive factor for the existence of this end. The state of adsorbate at the “end” provides the standard state of the supercritical adsorbed phase just like the saturated liquid, which is the end state of adsorbate in the subcritical adsorption. So the “end state” has to be precisely defined. To establish a definite relationship for the adsorbed phase density at the end state, abundant and reliable experimental data are still required.
Read more about this topic: Supercritical Adsorption
Famous quotes containing the words future and/or problems:
“How difficult the task to quench the fire and the pride of private ambition, and to sacrifice ourselves and all our hopes and expectations to the public weal! How few have souls capable of so noble an undertaking! How often are the laurels worn by those who have had no share in earning them! But there is a future recompense of reward, to which the upright man looks, and which he will most assuredly obtain, provided he perseveres unto the end.”
—Abigail Adams (1744–1818)
“I have a horror of people who speak about the beautiful. What is the beautiful? One must speak of problems in painting!”
—Pablo Picasso (1881–1973)