Ammonia removal in gasification plants
Towards this goal, the AMMONIA REMOVAL project developed the Selective Catalytic Oxidation (SCO) process. The study of this process provided an increased understanding of the reactions of ammonia and oxidisers on catalyst surface. Thereby, evaluation and specification of the most important properties that a catalyst should own for the oxidation of ammonia was performed. The effects of such properties as the surface acidity, metal type and concentration were studied and on this basis novel SCO catalysts were designed. This bulk preparation of catalysts was also optimised in terms of impregnation methods, conditions of drying and calcinations; that is heating rate, dwell temperature and time. Additionally, the study of the SCO process allowed its optimisation and the exploration of the possibilities of its implementation on a pilot scale. Therefore, after evaluation of several different gas phase kinetic models, a simple four reaction heterogeneous model was selected. The addition of this model to the gas phase mechanism was found to reproduce the same results with those observed with the use of the newly designed catalyst. This predictive model may very well prefigure the conversion of ammonia and hydrogen under various experimental conditions of temperature and oxygen concentration. The results of the AMMONIA REMOVAL project are expected to find useful applications in the development of catalytic gas cleaning for gasification processes. The kinetic model for SCO may also be of great value for modelling other similar problems including hot gas cleaning of coal gasifier gas. Most importantly, the gained understanding could form the basis for designing and optimising gas cleaning processes that involve catalysts. Interested parties are sought for further testing the robustness of the new catalyst design under industrial test conditions. Catalyst manufacturers and/or companies using gasification technologies are also sought to exploit the new catalyst design.