A Study of Water Adsorption and Desorption by a PBI Membrane and Its Impact on H_3PO_4 Transport

摘要

The objective of this study is to aid the development of an understanding of the mechanisms of H_3PO_4 loss and transport in PolyBenzImidazole (PBI)-type High Temperature Membranes (HTM) fuel cells. The isotherms for adsorption and desorption of water in PBI-type HTM are critical data and reported for the first time here for a commercially available membrane. Depending on their values, this adsorption/desorption could play an important role in the long-term dilution of acid and thereby affect (in the long-term) the transport of this acid and proton flux in the membrane. Inclusion of these data is necessary in the development of a mechanistic model that allows for design of new experiments and prediction of fuel cell performance.