首页| Rh/ZrO2@C(MIL) catalytic activity and TEM images. CO2 conversion performance and structural systematic evaluation of novel catalysts derived from Zr-MOF metallated with Ru, Rh, Pd or In
Rh/ZrO2@C(MIL) catalytic activity and TEM images. CO2 conversion performance and structural systematic evaluation of novel catalysts derived from Zr-MOF metallated with Ru, Rh, Pd or In
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A set of novel materials, denoted M/ZrO2@C(MIL) (M = Ru, Rh, Pd & In), were prepared by thermal transformation of MIL-140C containing 10% bipyridine linkers (MIL-140C-10), to provide sites for metal coordination within the framework. These materials were transformed into active catalysts for CO2 hydrogenation when heated in a gas mixture of H2 and CO2 (3:1), at 500 °C. The thermal treatment provided high surface area catalysts with high stability and high Ru or Rh metal dispersion which were very effective for the hydrogenation of CO2 to CH4, giving a CH4 production of 3.0-3.7 mol/g Ru/h or 4.2-4.3 mol/g Rh/h (at 400 °C, 33 bar and WHSV 23 L/h/g cat.). PXRD, XPS and TEM indicated that the effective catalysts consisted of nanoparticles of Ru~0 (2-5 nm) or Rh~0 (6 nm) associated with larger ZrO2 nanoparticles (10-20 nm), which were dispersed upon carbonaceous ribbons. Interestingly, at 250-350 °C, Pd/ZrO2@C(MIL) yielded mainly CO rather than CH4, with some CH3OH. The CH4 and CO production were not stable at 400 °C. TEM results for this catalyst indicated Pd~0 and ZrO2 nanoparticles (initially 20 nm and 10-20 nm diameter, respectively). The lower, unstable activity compared to Ru and Rh could have been due to the initially larger Pd particles and their tendency to grow in size with reaction time. In/ZrO2 has mainly been used to catalyse CH3OH production, but In/ZrO2@C(MIL) gave less CH3OH than In/monoclinic ZrO2 and was less selective. At 400 °C In/ZrO2@C(MIL) was a stable, reverse-water-gas-shift catalyst (producing 0.9 mol CO/g In/h at WHSV 20 L/g cat/h). The In was well dispersed in the ZrO2-C and of small particle size. The poor selectivity for methanol may have been due to the tetragonal phase of the ZrO2 and the low surface In concentration.
RuRhPdIn in ZrO2-CTetragonal ZrO2CO2 methanation temperature dependenceReverse-water-gas shiftMetal particle size/dispersion
Dalai S. Alqami、Marc Marshall、Thomas R. Gengenbach
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School of Chemistry, Monash University, Victoria, 3800, Australia
CSIRO Manufacturing, Clayton, Victoria, 3168, Australia
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