Renewable H₂ from Glycerol Steam Reforming: Effect of La₂O₃ and CeO₂ Addition to Pt/Al₂O₃ catalysts.

Abstract

Glycerol is the main byproduct of biodiesel production and its increased production volume derives from the increasing demand for biofuels. The conversion of glycerol to hydrogen-rich mixtures presents an attractive route towards sustainable biodiesel production. Here we explored the use of Pt/Al(2)O(3)-based catalysts for the catalytic steam reforming of glycerol, evidencing the influence of La(2)O(3) and CeO(2) doping on the catalyst activity and selectivity. The addition of the latter metal oxides to a Pt/Al(2)O(3) catalyst is found to significantly improve the glycerol steam reforming, with high H(2) and CO(2) selectivities. A good catalytic stability is achieved for the Pt/La(2)O(3)/Al(2)O(3) system working at 350 degrees C, while the Pt/CeO(2)/Al(2)O(3) catalyst sharply deactivates after 20 h under similar conditions. Studies carried out on fresh and exhausted catalysts reveal that both systems maintain high surface areas and high Pt dispersions. Therefore, the observed catalyst deactivation can be attributed to coke deposition on the active sites throughout the catalytic process and only marginally to Pt nanoparticle sintering. This work suggests that an appropriate support composition is mandatory for preparing high-performance Pt-based catalysts for the sustainable conversion of glycerol into syngas.

Challenges and strategies for optimization of glycerol steam reforming process

“…Similar behavior, in terms of performance enhancement, has been observed for Pt-based catalysts promoted with basic oxides like La2O3 [92] and MgO [88]. However, the La2O3 promoted catalyst only deactivated after 50 h time-on-stream, as can be seen in Fig. 14.…”

“…Montini et al [92] verified that the Pt/CeO2/Al2O3 catalyst, despite presenting improved performance, still deactivated after 20 h time-on stream (Fig. 14) [92].…”

“…14) [92]. This deactivation could be due to coke deposition on the active sites and only marginally due to Pt sintering.…”

“…The addition of ceria promoter has been verified as advantageous, but in this case for platinum-based catalysts [88,92,97]. As already mentioned, the addition of ceria to a support like alumina reduces its acidity, thereby improving the catalyst stability and H2 selectivity and reducing the formation of undesirable products and coke deposition.…”

Upgrading the Glycerol from Biodiesel Production as a Source of Energy Carriers and Chemicals—A Technological Review for Three Chemical Pathways

“…The addition of ceria to platinum catalysts, on an alumina basis, lowers its acidic content, upgrading thereby the catalyst stability and H 2 selectivity, and lessening the formation of impurities and coke deposition [139,142]. Also, it was shown that the energy requirement for CO adsorption on Pt-based catalysts was reduced by the application of metal alloys [143].…”