Issue No. 1, April

Abstract

Water-gas shift reaction is an important industrial reaction, used for producing synthesis gas and ammonia as well as pure hydrogen for supplying at PEM fuel cells. In this work, an overview on water gas shift reaction performed in Pd-based membrane reactors is shown, paying particular attention to the influence on the performances of some operating variables such as reaction temperature, reaction pressure, H₂O/CO molar ratio and sweep gas.

Abstract

Today, CO₂ capture from e.g. flue gas has becoming an emerging opportunity for membrane gas separation. The flue gas coming out from power plants contains about 10-15% CO₂, which should be separated before its sequestration. The most used membranes for this application are polymeric but they cannot be used at a high temperature. The flue gas exits at ca. 200°C, depending on the specific locations in the plant and, thus, it is highly desirable to separate it at high temperature.
An alternative class to polymeric membranes is represented by the ceramic one which comprises zeolites, carbons, silica, perovskites membranes, that exhibit high fluxes and thermal resistance. However, a great challenge is to fabricate them as thin layers, avoiding formation of cracks that compromise the separation. Today, new solutions are in progress for the production of ceramic membrane able to overcome these limitations. For example, hybrid membranes able to combine the properties of different materials are proposed. Moreover, new works are done on mixed-matrix membranes, comprising of a molecular sieve guest phase dispersed in a polymer host matrix [3] which combines the advantage offered by the two materials. This work proposes an overview on the main applications of ceramic membranes in CO₂ capture processes.