Advances in catalysts for membrane reactors

The overall goal of this study is to develop superior catalysts suitable for use in modem advanced slurry phase or membrane reactors. Successful investigations have produced an iron-based unsupported catalyst with high activity and extended catalyst life (improved attrition resistance). This catalyst was used by the authors to understand the phase transformations from iron oxide precursors after activation to iron carbide crystallites and to characterize the presence of characteristic amorphous carbon species that have been reported to envelop the spent Fe-FTS catalyst grains in form of surface layers. Previous studies suggest two different phases to be considered as the active phase including iron oxide and a mixture of x snd e -carbides (Table 1) and in some instances minor amounts of metallic iron, however the spatial distribution of the different... 

Whilst the basic process for generation and conversion of syngas is well established, production from biomass poses several challenges. These centre on the co-production of tars and hydrocarbons during the biomass gasification process, which is typically carried out at 800 °C. Recent advances in the production of more robust catalysts and catalytic membrane reactors should overcome many of these challenges. 

The application of permeable composite monolith membranes for the FT synthesis has been tested [122]. An overview of concepts associated with this reactor type has been presented (Figure 12.25) [123]. Novel uses of this concept have been advanced, and some experimental results have demonstrated the ability to operate at high CO conversion with metal FT catalysts by removal of the water produced during the synthesis [ 124] and the encapsulation of an FT catalyst by a zeolite membrane layer to effect upgrading reactions in the FT reactor [125]. The potential of this technique merits further studies to evaluate the ability to scale to a commercial level. 

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