Ce0.78Sn0.2Pt0.02O2−δ: A new non-deactivating catalyst for hydrogen production via water–gas shift reaction

We demonstrate the activity of Ce0.78Sn0.2Pt0.02O2−δ, a new catalyst, towards water–gas shift (WGS) reaction. Over 99.5% CO conversion to H2 is observed at 300 ± 25 °C. Based on different characterization techniques we found that the present catalyst is resistant to deactivation due to carbonate formation and sintering of Pt on the surface when subjected to longer duration of reaction conditions. The catalyst does not require any pre-treatment or activation between start-up/shut-down reaction operations. Formation of side products such as methane, methanol, formaldehyde, coke etc. was not observed under the WGS reaction conditions indicating the high selectivity of the catalyst for H2. Temperature programmed reduction of the catalyst in hydrogen (H2-TPR) shows reversible reduction of Ce4+ to Ce3+, Sn4+ to Sn2+ and Pt4+ to Pt0 oxidation state with oxygen storage capacity (OSC) of 3500 μmol g−1 at 80 °C. Such high value of OSC indicates the presence of highly activated lattice oxygen. CO oxidation in presence of stoichiometric O2 shows 100% conversion to CO2 at room temperature. The catalyst also exhibits 100% selectivity for CO2 at room temperature towards preferential oxidation (PROX) of residual CO in presence of excess hydrogen in the feed.

Figure optionsDownload as PowerPoint slideResearch highlights▶ OSC of Ce0.78Sn0.2Pt0.02O2−δ measured up to 250 °C is 3500 μmol g−1. ▶ Ce0.78Sn0.2Pt0.02O2−δ is an excellent catalyst for WGS with >99.5% conversion for 2 vol% of CO at 275 °C. ▶ No deactivation of the catalyst observed after 96 h of start-up/shut-down cycles. ▶ Both (a) CO oxidation in presence of stoichiometric oxygen and (b) PROX in presence of excess H2 show complete conversion to CO2 at room temperature. ▶ Formation of side products other than CO2 and H2 was not observed under WGS reaction conditions.