Application of catalysts to coal gasification processes. Incentives and perspectives

There are several processes used for coal gasification, but these have three characteristic types of reactors — moving-bed, fluidized-bed and entrained phase. Design and comparison of different processes and reactors is possible if kinetic data relevant to technical performance of processes are available. The state of reaction kinetics of the non-catalysed and catalysed steam-carbon reaction as the basic coal gasification reaction is discussed. Catalysts only have effects on gasification rates in the temperature range of chemical reaction or pore diffusion control. Furthermore the increase in reaction rates by catalysts can also be reached without using catalysts. Therefore the application of catalysts seems not to be attractive in conventional gasification processes because the advantages (less coal and oxygen consumption and lower heat losses) are compensated by their disadvantages (additional costs, side effects). Only such processes in which a temperature increase is limited for different reasons does the application of catalysts have significant advantages. Such processes are the allothermal gasification using nuclear heat and processes leading to synthetic natural gas (SNG).