Facile Thermodynamically Controlled Synthesis of Intermetallic Zn_1-xPd_x/Al₂O₃ and Its Methanol Steam Reforming Properties

High-performance heterogeneous catalytic materials are most frequently based on supported nanoparticles to gain high dispersion and thus high atom efficiency. The materials are usually obtained by kinetically controlled synthesis, making repetitive synthesis of materials with identical properties a challenge. While this holds for monometallic-supported particles, the situation is even more severe with binary-supported substitutional alloys or intermetallic compounds, where control of the homogeneous elemental composition of the nanoparticles comes close to an art. We propose an innovative synthesis route to Zn_1-xPd_x/Al₂O₃, controlling thermodynamically the composition and homogeneity of the Zn_1-xPd_x particles─an intermetallic compound having a significant homogeneity range and catalyzing numerous reactions. The thermodynamic control is achieved by the direct reaction of supported palladium nanoparticles with gaseous zinc. The resulting Zn_1-xPd_x/Al₂O₃ samples are characterized in detail concerning their particle composition, particle size distribution, and crystal structure of the intermetallic nanoparticles, using XRD, TEM, XPS, ICP-MS and ICP-OES. Subsequent testing in methanol steam reforming reveals excellent catalytic properties.