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 m 2 ·g −1 ) support possesses a higher surface area than the ZnO-R (1.3 m 2 ·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.

Effect of support on the performance of PtRu-based catalysts in oxidative steam reforming of ethanol to produce hydrogen

“…The Al 2 O 3 was purchased from Merck (γ-form, 142 m 2 ⋅g −1 ), while the others were self-synthesized. The ZrO 2 (130 m 2 ⋅g −1 ) was prepared using the sol-gel method ( Bi et al, 2007a ), the CeO 2 (106 m 2 ⋅g −1 ) was prepared using a simple reduction-oxidation method ( Siang et al, 2010 ), the Co 3 O 4 (102 m 2 ⋅g −1 ) and NiO (104 m 2 ⋅g −1 ) were prepared by the precipitation-oxidation method ( Wang et al, 2005a ; Lai et al, 2006 ), and the ZnO (89 m 2 ⋅g −1 ) was obtained through the thermal decomposition of Zn(OH) 2 ·2ZnCO 3 ·xH 2 O (Stream) in the air ( Chiou et al, 2012 ), respectively. The supported PtRu catalysts were prepared by the impregnation method using an aqueous solution of H 2 PtCl 6 (Merck) and RuCl 3 (Strem) as precursors (the loading of each component was 1.5 wt%).…”

Effects of surface chemistry on the mechanochemical decomposition of tricresyl phosphate

“…This is likely due to the higher surface energy and adhesion of TCP molecules on iron and iron carbide compared to iron oxide. 13 Previous DFT calculations suggested that the surface energy of a-Fe(110) (2.3 J m À2 ) 51 and Fe 3 C(010) (2.2 J m À2 ) 52 is much larger than Fe 3 O 4 (001) (1.0 J m À2 ). 98 For the iron and iron carbide systems, the friction coefficient decreases with increasing temperature (Table S2, ESI †); in contrast, the Derjaguin offset increases with increasing temperature (Table S3, ESI †).…”

“…50 Magnetite was selected since previous experiments have shown that it is the major oxide formed on the surface of bearing steel following tribometer experiments. 37 We used an a-Fe(110) for the iron surface, 51 Fe 3 C(010) as the cementite surface, 52 and Fe 3 O 4 (001) with a subsurface cation vacancy (SCV) reconstruction as the magnetite surface 53 due to their relatively low surface energies.…”

“…This may be due to the differences in surface energies of the three ferrous surfaces, as discussed in the previous section. 51,52,98 Higher surface energies promote stronger molecular adsorption 100 and thus faster TCP decomposition. Indeed, DFT calculations have shown that adsorption is a crucial step the decomposition of TCP on iron surfaces.…”