Ru-zirconia catalyst derived from MIL140C for carbon dioxide conversion to methane

A novel material, designated Ru/ZrO2@C(MIL), was prepared by thermal transformation of metal organic framework (MOF), MIL-140C-10, in which 10 % of the conventional biphenyl-dicarboxylate linkers had been substituted with bipyridyl-dicarboxylate linkers, thereby providing sites for Ru coordination with the framework. This MOF precursor was compositionally and morphologically transformed when heated, at 500 °C, in a mixture of H2 and CO2 (3:1). The transformation afforded a high surface area product (114 m2/g) with exceptional stability and high Ru metal dispersion which was very effective as catalyst for the hydrogenation of CO2 to CH4, giving a CH4 production of 53 mol/g Ru/h (at 350 °C, 40 bar and WHSV 344 L/h/g cat.). TEM results show that the active form of the catalyst was a partially degraded (‘unzipped’) MOF structure where Ru° and ZrO2 nanoparticles (2−5 and 10−20 nm diameter, respectively) were dispersed upon carbonaceous ribbons.