Potential of metal monoliths with grown carbon nanomaterials as catalyst support in intensified steam reformer: a perspective
A monolithic catalytic support is potentially a thermally effective system for application in an intensified steam reforming (SR) process. In contrast to ceramic analogues, metal monoliths exhibit better mechanical strength, thermal conductivity and a thermal expansion coefficient equivalent to that of the reformer tube. A layer of carbon nanomaterials grown on the metal monolith’s surface can act as textural promoter offering sufficient surface area for hosting homogeneously dispersed catalytically active metal particles. Carbon nanomaterials possess good thermal conductivities and mechanical properties. The future potential of this system in SR is envisaged based on hypothetical speculation supported by fundamental carbon studies from as early as the 1970s and sufficient literature evidence from relatively recent research on the use of monolith and carbon in catalysis. Thermodynamics and active interaction between metal particle surface and carbon-containing gas result in coke deposition on the nickel-based catalysts in SR. The coke is removable via gasification by increasing steam to carbon ratio to above stoichiometric but risks a parallel gasification of the carbon nanomaterials textural promoter, leading to nickel particles sintering. We present our perspective based on literature that under the same coke gasification conditions, the highly crystallized carbon nanomaterials maintains high chemical and thermal stability.