Free energy change in the adsorptional displacement of butene by water from a catalyst surface

Abstract

1. A method is proposed for the determination of equilibrium constants for the adsorptional displacement of some substances by others from a catalytically active surface; it yields also the free energies of the processes, and these determine the stability of the intermediate adsorption complexes. 2. It has been found that water vapor effects the adsorptional displacement of butene from the catalyst surface. The relative adsorption coefficient is about 3.1 at 560° and diminishes with many temperature, attaining the value of 2.0 at 600°. The free energy of displacement of butene by water from the active catalyst surface is −4308 cal/ mole at 833° K. and - 2702 cal−/ mole at 853° K. Moreover; water vapor suppresses the conversion of butadiene into polymerization products, which give resinous films on the catalyst and so poison ft irreversibly. 3. We have observed an interesting previously undescribed example of the acceleration of the condensation of butadiene on the catalyst surface under the. influence of small addition (about 10%) of water vapor. It was established that, under these. conditions, water vapor itself would not bring abort irreversible poisoning of the catalyst.