Hydrogen Sulfide Effect on Hydrogen Entry into Iron - A Mechanistic Study
Abstract
The recently developed I-P-Z model is modified in order to analyze the observed enhanced permeation of hydrogen that occurs in the presence of hydrogen sulfide during cathodic hydrogen charging of iron. The modification accounts for the fact that the energy of adsorption becomes coverage dependent at the higher coverages and affects the hydrogen evolution reaction (h.e.r.)in the presence of H2S. Charging experiments were performed on Ferrovac E-Iron membranes 0.5 mm thick using a Devanathan-Stachurski cell in deaerated, preelectrolyzed solutions made from 0.1M HCIO4 and 0.1M NaCIO4 with pH values of 1 and 2. The transfer coefficient, alpha, exchange current density, io, thickness-dependent absorption-adsorption rate constant k , recombination rate constant, k sub 3, surface hydrogen coverage, Theta sub H, and discharge rate constant, k1 superscript, were obtained by application of the model to the experimental results. As a result, the role of H2S has been clarified. While Theta sub H is increased in the presence of H2S, the overpotential, eta, is decreased consistent with an observed increase in alpha, and the increased H entry is found to be the result of a decreased k sub 3 as well as the increased alpha. In addition, a very important relationship has been derived that will enable the calculation of the absorption, K sub abs, and adsorption, K sub ads, rate constants from the electrochemical permeation results for different membrane thicknesses.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1989
- Accession Number
- ADA216214
Entities
People
- Howard W. Pickering
Organizations
- Pennsylvania State University