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Keywords:

  • aluminum;
  • heterogeneous catalysis;
  • cerium;
  • silicon;
  • platinum

Abstract

Ce0.88Si0.1Pt0.02O2−δ and Ce0.88Al0.1Pt0.02O2−δ catalysts were synthesized by using a low-temperature sonochemical method and characterized by using XRD, TEM, XPS, FTIR, and BET surface analyzer. The catalytic activities of these compounds were investigated for the water–gas shift reaction in the temperature range of 140–440 °C. The substitution of Si in Ce0.98Pt0.02O2−δ increased the releasing capacity of lattice oxygen, whereas the substitution of Al decreased the reducibility of Ce0.98Pt0.02O2−δ, as evidenced by hydrogen temperature-programmed reduction studies. However, both the catalysts showed a considerable improvement in terms of activity and stability compared to Ce0.98Pt0.02O2−δ. The combined activity measurement and characterization results suggest that the increase in the oxygen vacancy, which acts as a dissociation center for water, is the primary reason for the improvement in the activity of modified Ce0.98Pt0.02O2−δ. Both the catalysts are 100 % selective toward H2 production, and approximately 99 % conversion of CO to CO2 was observed at 260 and 270 °C for Ce0.88Si0.1Pt0.02O2−δ and Ce0.88Al0.1Pt0.02O2−δ, respectively. These catalysts do not deactivate during the daily startup/shutdown operations and are sustainable even after prolonged reaction. Notably, these catalysts do not require any pretreatment or activation during startup/shutdown operations.