Supported Rh nanoparticles on CaO?SiO2binary systems for thereforming of methane by carbon dioxide in membrane reactors

JOHN MÚNERA, BETINA FAROLDI, EMANUEL FRUTIS, EDUARDO LOMBARDO, LAURA CORNAGLIA, SILVIA GONZÁLEZ CARRAZÁN.

APPLIED CATALYSIS A-GENERAL

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2014 vol. 474 p. 114 - 124

0926-860X

A set of Rh catalysts supported on a binary CaO?SiO2system with different CaO content was prepared toinvestigate their textural and structural properties, Rh particle size, and catalytic performance in the dryreforming of methane reaction.The Rh nanoparticles and nanocrystalline structures in the reduced catalysts were characterizedthrough HRTEM and CO chemisorption. EDX mapping showed that CaO is uniformly distributed on SiO2and that no segregation is detected between them. Rh nanoparticles of about 1?2.6 nm were observed.These particle sizes indicate that Rh is well dispersed on the catalyst surface and that no agglomerationexists.The incorporation of the promoter (CaO) to the silica support induced an increase in the metal disper-sion from 8% in Rh/SiO2to 22?80% in Rh/CaO?SiO2catalysts. However, the Rh dispersion decreased asthe CaO loading also increased in the binary supports.For the high CaO load solids, a high stability was observed after 80 h on stream for the dry reform-ing of methane. In addition, the solid with 27% CaO presented the higher methane reaction rate. As aconsequence, this solid was selected for its application in a membrane reactor under different conditions.The increase of methane conversion with reaction pressure at high sweep gas flow rate indicates thatthe separation efficiency of the Pd membrane is sufficiently high to dominate the performance of Pdmembrane reactors under those conditions.