Surface Area Effect of Zinc Oxide for Steam Reforming of Ethanol over Supported-Platinum Catalysts

Abstract

The effect of surface area over the ZnO-supported platinum catalysts on the catalytic performance of steam reforming of ethanol (SRE) has been studied. Various surface area of ZnO is prepared through two routes: reflux (assigned as ZnO-R), thermal decomposition under air (assigned as ZnO-A) and under N₂ (assigned as ZnO-N). Also, the commercial ZnO (assigned as ZnO-C) is chosen as reference. Four Pt/ZnO catalysts (3 wt% loading of Pt) are prepared by incipient wetness impregnation (assigned as Pt-R, Pt-A, Pt-N and Pt-C, respectively). The BET measurement shows that the ZnO-A (89 m²·g^-1) support possesses a higher surface area than the ZnO-R (1.3 m²·g^-1). The catalytic activity on the SRE reaction is evaluated in a fixed-bed reactor under 22,000 h^-1 GHSV and H₂O/EtOH molar ratio of 13. The results show that total ethanol conversion is observed at 225°C and 400°C over the Pt-A and Pt-R catalysts, respectively. When the temperature exceeds 350°C, acetaldehyde decomposition and acetaldehyde steam reforming are competitive on the platinum catalysts to promote H₂ production. The small particle size catalyst of Pt-A favors the decomposition of acetaldehyde to produce CH₄ and CO, and the large particle size catalyst of Pt-R favors the steam reforming of acetaldehyde to produce CH₄ and CO₂. [DOI: 10.1380/ejssnt.2012.431]