Kinetic and process study of ethanol steam reforming over Ni/Mg(Al)O catalysts: The initial steps

Elucidation of metal and support effects during ethanol steam reforming over Ni and Rh based catalysts supported on (CeO2)-ZrO2-La2O3

“…This is more noticeable on the TOF plot (Figure 5c), where a clearly negative reaction order in respect to water is obtained for the latter catalysts, whereas on the ceria containing ones the slope is still negative but much closer to zero. Various studies, including our previous work on Ni/SiO2 [25], have suggested that a negative partial reaction order for steam indicates the competitive adsorption of ethanol and water for the same active sites, with the metal surface being gradually saturated by adsorbed water species [63,64]. Clearly, the high oxygen mobility and large oxygen storage capacity of CeO2 allows for an efficient dissociation of steam across its entire surface and a fast delivery of O species to the metal that prevents to a large degree the latter's saturation by steam, as carbon-containing surface intermediates are effectively oxidised.…”

Kinetic analysis of the steam reforming of ethanol over Ni/SiO2for the elucidation of metal-dominated reaction pathways

“…Nonetheless, a range of additional products have also been reported in literature, namely methane, acetaldehyde, ethylene, and acetic acid participating in reactions (3) to (10), while less frequently even acetone has been observed. 7 Among several available kinetic investigations on Ni, the reaction order has been mainly reported as positive for ethanol [8][9][10][11] and negative 12,13 for water, the latter fact pointing to the competitive adsorption of ethanol and water on the same site. A range of apparent activation energy values from about 32 kJ mol -1 to 90 kJ mol -1 have also been reported 7,8,14,15 indicative of the large effect of catalyst properties and/or operating conditions on the parameter.…”

“…The reaction mechanism of ESR has also been the subject of several experimental and theoretical studies. 13,[16][17][18] Sanchez et al 19 investigated ESR on Pt, Ni and PtNi catalysts supported on γ-Al 2 O 3 , suggesting the main reaction pathway to be that of ethanol dehydrogenation followed by the decomposition of acetaldehyde or the oxidation of the latter towards surface acetate species. Sutton et al 20 developed a comprehensive microkinetic model for ESR over Pt based on elaborate DFT calculations, exploring oxidative dehydrogenation reactions as possible alternatives to pure decomposition ones.…”

“…The formation of coke and its type have also been the focus of different studies, [21][22][23] with the Boudouard reaction (11), the decomposition of methane (12) and the polymerization of ethylene (13) highlighted as the main pathways to carbon deposition. Noble metals catalysts have typically shown high activity with negligible coke formation, 24,25 however their high cost has led to the extensive investigation of non-noble metal catalysts as well.…”

Ethanol Steam Reforming on Ni-Based Catalysts: Effect of Cu and Fe Addition on the Catalytic Activity and Resistance to Deactivation

“…When ethanol molecules are adsorbed on the metal surface, ethanol dehydrogenation reaction occurred at the initial reaction step and mainly through a Cu site in the Cu–Ni­(Fe) alloy form acetaldehyde. Meanwhile, the acetaldehyde is transformed to CH 4 and CO on a Ni site in alloys or Ni–Ni, because the C–C bond is more easily broken in acetaldehyde than that in ethanol . This reaction appears to be the predominant pathway at lower temperature (∼300 °C) from catalytic result.…”