Methanol steam reforming on LaCo1−x−yPdxZnyO3±δ

Abstract Perovskite-type oxides LaCo 1− x − y Pd x Zn y O 3± δ are studied for the methanol steam reforming (MSR) reaction. LaCo 1− x − y Pd x Zn y O 3± δ with and without Co substitution by Pd and/or Zn are synthesized by the amorphous citrate method. The effect of substitution on the reducibility of the materials is investigated by in situ XRD and differential thermal/thermogravimetric analysis (DTA/TG) during temperature programmed reduction (TPR) with hydrogen. From this, the phase composition evolving as a function of temperature is determined. The TPR data indicate that the reducibility of the materials strongly depends on the substituent, i.e. , Pd or Zn. The former increases the reducibility, while substitution by Zn decreases the reducibility. Materials containing both Pd and Zn exhibit intermediate reducibility as compared to the un-substituted LaCoO 3± δ (LCO) and mono-metal substituted LaCo 0.873 Pd 0.127 O 3± δ (LCPO) and LaCo 0.89 Zn 0.11 O 3± δ (LCZO). In general, the metal ions in the materials are completely reduced at 590 °C, except La 2 O 3 . After reductive pre-treatment at 590 °C for 2 h, the MSR performance of the materials is evaluated between 150 and 400 °C while keeping comparable CH 3 OH conversion to assess the product-concentration-dependent CO 2 selectivity. These results confirm that the CO 2 selectivity is strongly dependent on the material composition. For example, the un-substituted LCO, LCPO and LCZO show a CO 2 selectivity of around 13% at 300 °C, while it is improved to 80% on both Pd and Zn containing LaCo 0.85 Pd 0.075 Zn 0.075 O 3± δ (LCPZO-15).