Heats of water adsorption on microporous carbons from nitrogen and methane carriers

Simultaneous determinations in the flow adsorption microcalorimeter of the amounts and heats of adsorptions designed to discover to what extent the adsorption of water vapour on a heterogeneous carbon and a carbon molecular sieve is influenced by the presence of nitrogen and methane at atmospheric pressures and how the differential heats of displacement of these gases by water change with its increasing uptake. The work revealed that the adsorption of water is strongly influenced by the nature of the carrier gas from which the adsorption takes place. Water uptake from methane is much greater than that from nitrogen, but its heats of adsorption are much lower. For both carrier gases the differential heats of water adsorption at low surface coverages on the carbon with the wider range of pore diameters greatly exceeds the heats of water vapour condensation at room temperatures. (C) 2001 Elsevier Science Ltd. All rights reserved.