Most hydrocarbon fuels like petroleum, natural gas and coal contain sulphur compounds which after high-temperature processing are converted mainly to hydrogen sulphide. The removal of sulphur compounds is critical to meet both increasingly tightening fuel specifications in the case of the petroleum industry as well as for the optimal operation of power stations in the case of the electricity generation.
The latter is especially applicable to modern technologies employed in highly efficient coal power stations such as the newer Integrated Gasification Combined Cycle (IGCC). In all of these, cost effective and efficient commercial desulphurization is required! Conventional methods of desulphurization involve absorption of the acid component using either calcium based slurry systems or amine based solvents that are toxic, corrosive and flammable.
The chemical affinity of H2S to surface metal sites has resulted in the recent development of metal oxide sorbents that provides an elegant alternate with zinc oxide (ZnO) based sorbents being regarded as amongst the best materials for hot gas desulphurization. The University of KwaZulu-Natal (UKZN) has gone a step further and using a novel preparation technique, prepared zinc oxide absorbents with the following features:
- improved dispersion of active metal on the support structure.
- improved loading capability of the active metal on the support structure.
- reduced agglomeration of metal particles on the support structure.
This translates to a superior zinc oxide sorbent with enhanced sulphur removal capacity of >70% compared to other metal based absorbents. The benefits to end users of desulphurisation processes are:
- Drop-in replacement if using conventional metal based sorbents,
- Extended absorber running times,
- Reduced absorbent regeneration frequency,
- Reduced operational and maintenance costs.
The benefits to producers of metal based absorbent:
- production process that is free from toxic and flammable solvents,
- Elegant production process that is free from toxic and flammable solvents,
- Minimum additional capital investment and operational costs enable the manufacture of a superior metal based sorbent.
Principle Investigator: Dr David Lockhat