One-pot fabrication of an efficient 3D porous SiC based monolithic catalyst for methanol steam reforming via a carbon encapsulation strategy

Methanol steam reforming (MSR) is an effective technique to produce hydrogen for fuel cell vehicles (FCVs). Monolithic catalyst with features of good thermal conductivity and 3D porous structure boosts the on-board MSR reaction activity. In comparison to traditional coating method, one-pot fabricated SiC based monolithic catalyst possesses advantages of higher loading amount and enhanced adhesion of active components. However, a notable challenge arises as the active sites become susceptible to coverage, and the porous structure tends to be obstructed by the binder during the fabrication procedure. Herein, a highly active 3D porous SiC based monolithic catalyst with carbon layers protected Cu/Al2O3 was successfully fabricated, in which the carbon encapsulation structure serves as "protective umbrella" for active sites and porous structure. Complementary characterizations including Scanning electron microscope, Transmitted electron microscope, H2 temperature-programmed reduction and N2O chemisorption are employed to disclose the protection mechanism of carbon layers. When the glass frit binder melts and infiltrates into the gaps among SiC and powder catalyst particles, the amorphous carbon outside alumina prevents the blockage of mesoporous structure, and the graphite carbon acts as the protectant outside the Cu nanoparticles. Subsequently, the carbon layers decompose, exposing the highly active Cu sites. This work presents a novel approach to the design and development of monolithic catalysts with high loading amount and enhanced loading strength of active components, which may exhibit broad applicability in the fabrication of other monolithic catalysts.