Highly stable nano Ce–La catalyst for hydrogen production from bio-ethanol

Abstract

The catalytic activity of a metal free nano particle, whose size ranged from 1–10 nm, was studied according to HRTEM and DLS results. The effect of reaction temperature (300–600 °C) on the catalytic activity of the prepared catalysts was studied in a flow system under atmospheric pressure with an ethanol–water molar ratio of 1 : 10. Selectivity was calculated for the products H₂, CO, CO₂ and CH₄, as well as the intermediates C₂H₆, C₂H₄, CH₃CHO and CH₃COCH₃, at different reaction temperatures. It was found that the addition of La increased the activity and stability of the Ce catalyst. H₂ was produced at the lowest temperature (300 °C) over Ce–La_0.2 & Ce–La_0.5 catalysts. Complete conversion of ethanol with high hydrogen selectivity was obtained at 500 °C over Ce–La_0.2 catalysts. Further increases of La content lead to decrease in the catalyst activity in accordance with the decrease of surface area to 9.6 m² g⁻¹. To study the stability of the prepared catalyst, the ESR reactions of Ce–La_0.2 and Ce–La₁ catalysts were investigated at 500 °C for 15 h. It was found that the Ce–La_0.2 catalyst is more stable than the Ce–La₁ catalyst over entire 15 h. Finally, we can say that lanthanum oxide (La₂O₃) is particularly suitable as a modifier due to its effectiveness in the prevention of sintering and improvement of thermal resistance at high temperatures. This oxide is also able to gasify the coke through the formation of La₂O₂CO₃ oxy-carbonate.