Review on Copper and Palladium Based Catalysts for Methanol Steam Reforming to Produce Hydrogen

Abstract

Abstract:Methanol steam reforming is a promising technology for producing hydrogen for onboard fuel cell applications. The methanol conversion rate and the contents of hydrogen, carbon monoxide and carbon dioxide in the reformate, significantly depend on the reforming catalyst. Copper-based catalysts and palladium-based catalysts can effectively convert methanol into hydrogen and carbon dioxide. Copper and palladium-based catalysts with different formulations and compositions have been thoroughly investigated in the literature. This work summarized the development of the two groups of catalysts for methanol steam reforming. Interactions between the activity components and the supports as well as the effects of different promoters were discussed. Compositional and morphological characteristics, along with the methanol steam reforming performances of different Cu/ZnO and Pd/ZnO catalysts promoted by Al 2 O 3 , CeO 2 , ZrO 2 or other metal oxides, were reviewed and compared. Moreover, the reaction mechanism of methanol steam reforming over the copper based and palladium based catalysts were discussed.

Redox Behavior of a Copper‐Based Methanol Reformer for Fuel Cell Applications

“…[5][6][7][8] Commercially available copper-based catalysts( Cu/ZnOa nd Cu/ZnO/Al 2 O 3 )h ave been widely used for hydrogen production from methanol, whereas experimental studies have also included group 8-10 metal-based catalysts supported mainly on ZnO and CeO 2 . [51][52][53][54][55][56][57][58][59][60][61][62][63][64] Regardingt he former catalysts,the presence of highly dispersed reduced copper species together with stable redox behavioru nder methanol reforming conditions are key requirements for the achievemento f high activitya nd low CO selectivity.N evertheless,c ommercial CuZn(Al)O x catalysts have not been designed for portable energy applications,a nd apart from commont hermal sintering, their main drawback pertains to pyrophoricity phenomena, which appear when the used catalyst is exposed to air. Rapid re-oxidation of the metallic copper species takes place to al arge extent (sometimes autoignition might occur), thus resulting in sintering of copper nanoparticles and irreversiblec atalyst deactivation.…”

Investigation of the Inhibiting Role of Hydrogen in the Steam Reforming of Methanol

“…In spite of high reducibility of palladium oxide phases in PdZnCrO x catalyst, the reduction was performed at higher temperature to create PdZn alloy phases. The surface atoms of such phases form active centers in SRM process . High‐temperature TPR peaks indicate that PdZn alloys can be formed in the PdZnCrO x catalyst above 300 °C.…”

“…The surface atoms of such phases form active centers in SRM process. [30] High-temperature TPR peaks indicate that PdZn alloys can be formed in the PdZnCrO x catalyst above 300°C. It is worth to note that an application of high reduction temperatures, i. e. 500 or 600°C may lead to fast alloy formation and simultaneously to the strong sintering of metallic nanoparticles and sublimation of ZnO.…”

“…Relevant experimental studies have been also performed for noble metal catalysts, mainly palladium and platinum supported on zinc, indium and gallium oxides. [30][31][32][33][34][35][36][37][38][39][40][41][42][43][44][45] Unlike methanol synthesis, which is also carried out on similar catalysts and temperatures, SRM process is not limited by thermodynamic constraints at low temperatures. Thermodynamic restrictions play a lesser role in SRM, as the inverse of methanol synthesis, steam reforming and decomposition reactions can be considered irreversible at atmospheric pressure.…”

Development of an Efficient Methanol Production Process for Direct CO2 Hydrogenation over a Cu/ZnO/Al2O3 Catalyst

“…Converting CO 2 into valuable intermediate chemicals and products (such as methanol, carbonates, formic acid, methane or kerosene) is economically of interest as can potentially recoups the costs of CO 2 capture and conversion [10][11][12]. Methanol is one of the possible fuel candidates that can be made by CO 2 hydrogenation [13][14][15]. Methanol production and demands have shown a substantial increasing trend in the coming years.…”