Although many organic compounds are known to inhibit corrosion, in most cases it remains unknown how they specifically interact with a surface and how they decrease the corrosion rate. This lack of mechanistic knowledge currently makes the design and choice of new active compounds a case of trial and error. Understanding these organic molecule-metal surface interactions could lead to the design of new corrosion inhibitors for the oil and gas industry.In this project it is intended to move the understanding of corrosion inhibition and other surface phenomena from empirical observation towards a mechanistic understanding. Using a combination of surface sensitive techniques such as vibrational sum frequency generation and X-ray photoelectron spectroscopy, and theoretical modelling through the preparation of model complexes of relevant corrosion inhibitors.Two families of corrosion inhibitors have been studied and are presented here. For nitrogen based corrosion inhibitors a combination of theoretical calculations and experimental analysis of vibrational modes of model compounds have proved to be a good method to assist in understanding of surface phenomena.For phosphorus based corrosion inhibitors an extensive study of model compounds has been done. In addition to this, different phosphonic acids and phosphate esters have been studied on a Fe (110) and steel surfaces in ultra high vacuum and in more realistic conditions using near ambient pressures in order to investigate if changes in the environmental conditions lead to a different behaviour. These have been compared to the study of PAE 136, a commercial corrosion inhibitor composed by a mixture of phosphate esters used in the extraction of oil, proving that one of the selected model compounds has a better inhibitive activity in both an ideal and a more realistic system.The results presented in this thesis demonstrate that every corrosion inhibitor needs to be tested in the conditions in which it is going to be used as it is not possible to predict if a given active compound is going to have the same behaviour for different environments.
|Date of Award
|1 Aug 2017
- The University of Manchester
|Richard Winpenny (Supervisor) & Rob Lindsay (Supervisor)
- Inorganic chemistry