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Support effects on the structure and performance of ruthenium catalysts for the Fischer\u2013Tropsch synthesis
The influence of support and metal precursor on Ru-based catalysts has been studied in the
Fischer\u2013Tropsch synthesis (FTS) combining flow reactor and quasi in situ infrared spectroscopy
experiments. A series of supported ruthenium catalysts (3 wt.%) have been prepared using two
different TiO2 (P25, 20% rutile and 80% anatase; Hombifine, 100% anatase) and SiO2Al2O3
(28% Al2O3) as supports and RuCl3nH2O as metal precursor. The catalysts were labeled as
RuTi0.8, RuTi1 and RuSA respectively. Another catalyst (RuTi0.8N) has been synthesized with
TiO2P25 and Ru(NO)(NO3)3. After thermal treatments in air at 723 K and hydrogen at 443 K,
ruthenium metal particles are agglomerated when pure anatase TiO2 and SiO2Al2O3 are used as
supports, leading to low active catalysts. In contrast, and despite the lower specific surface area of
TiO2P25 as compared to that of the other supports, well dispersed Ru particles are stabilized
on titania P25. Remarkably, electronic microscopy studies demonstrate that Ru is deposited
exclusively on the rutile phase of TiO2P25. The catalytic performance shown by all these
catalysts in FTS reactions follows the order: RuTi0.8 4 RuTi0.8N 4 RuSA c RuTi1. The same
trend is observed during quasi in situ FTS experiments conducted in an infrared (IR) spectroscopy
cell. The FTIR spectra of TiO2P25 supported samples show that both samples behave similarly
under the FTS reaction. This work shows that the structure of the support, rather than its specific
surface area or the Ru precursor, is the parameter that determines the dispersion of Ru particles,
hence their catalytic performance