The application of microwaves to some heterogeneously catalysed reactions
Three heterogeneously catalysed reactions have been investigated using both conventional and microwave heating of the catalyst bed. The oxidative coupling of methane reaction has been widely studied using conventional methods of catalyst heating but only limited works have investigated the continuous microwave heating of catalysts. This research compares the two methods of catalyst heating in detail. Catalysts based on rare - earth oxides and chloride containing materials were studied. The combustion of methane reaction has also been studied under microwave and conventional heating methods. The reaction has attracted some attention in recent years with the increasing research in the area of natural gas powered vehicles. Emission regulations for the automotive industry are becoming increasingly stringent and the clean up of exhaust emissions from natural gas vehicles is of increasing interest. For both of the above reactions, the microwave heated example occurred at lower bulk temperatures than the conventionally heated reaction. However, documented equilibrium constant calculations show that the actual reaction temperature was far in excess of the observed bulk temperature. It is therefore postulated that there exist within the catalyst bed small areas which are at elevated temperature relative to the observed bulk temperature. Such areas are thought to be where the reaction actually occurs and have been termed "hot spots".