MnO_x-Promoted, Coking-Resistant Nickel-Based Catalysts for Microwave-Initiated CO₂ Utilization

Abstract

The most important factors in improving the stability of nickel-based catalysts for methane reforming with carbon dioxide (so-called methane dry reforming, MDR) lie both in suppressing carbon formation and inhibiting metal sintering at the high operating temperatures of this process (typically above 700 °C). Many efforts had been made to overcome these challenges, for example, by enhancing metal catalyst-support interactions. In this work, we used microwaves as an energy source to drive the MDR reactions under mild conditions with an overall measured catalyst bed temperature of below 220˚C. High CH4 conversion of ca. 94% and 97% conversion of CO2 were achieved over manganese-oxide modified ZrO2-supported nickel catalysts, exhibiting excellent anticoking properties. Compared with Ni/ZrO2 and Mn/ZrO2 catalysts, the Ni-Mn bimetal catalytic system stabilizes the catalytic activity of MDR by suppressing carbon deposition with the mixedvalent Mn 3+ /Mn 2+ chemical states enhancing the absorption and conversion of CO2 during the reactions.

Activated Carbon Supported Non-noble Bimetallic Ni-Based Catalysts for Nitrocyclohexane Hydrogenation to Cyclohexanone Oxime under Mild Conditions

“…Figure shows the Ni 2p 3/2 XPS patterns of Ni/AC and bimetallic Cu-Ni/AC. As shown in Figure , Ni 2p 3/2 XPS spectra can be fitted into three components; the peaks around 853.1, 854.6, and 856.6 eV are attributed to Ni metal, Ni oxide (NiO), and Ni hydroxides (Ni­(OH) 2 and NiOOH), respectively. , Additionally, the peak at 861.7 eV is ascribed to the shake-up satellite, which is due to the multielectron excitation of high-valence nickel. , Noticeably, it can be observed from Figure b,c that the peak intensity of Ni metal increases with the introduction of a small amount of Cu (0.5 and 1 wt %), indicating that Cu can effectively promote NiO reduction and facilitate metal Ni exposure. ,, However, as can be seen in Figure d–g, the intensity of Ni 0+ decreases with the introduction of excessive Cu, and the reason may be that excessive Cu can promote the formation of larger metal oxide nanoparticles and NiO–CuO eutectic so as to inhibit NiO reduction . These results are in agreement with the H 2 -TPR results in Figure .…”

“…XPS. 43,44 Additionally, the peak at 861.7 eV is ascribed to the shake-up satellite, which is due to the multielectron excitation of high-valence nickel. 19,20 Noticeably, it can be observed from Figure 6b,c that the peak intensity of Ni metal increases with the introduction of a small amount of Cu (0.5 and 1 wt %), indicating that Cu can effectively promote NiO reduction and facilitate metal Ni exposure.…”

The effect of adsorbed oxygen species on carbon-resistance of Ni-Zr catalyst modified by Al and Mn for dry reforming of methane

“…3.1 Catalytic activity for CO 2 reforming of methane at medium temperature The effect of Al and/or Mn promoters was investigated in previous work [25,28,32,33]. It was shown that the catalytic performance of Al-promoted catalysts was higher than that of non-promoted catalyst.…”

CO2 Capture and Utilization Editorial

“…). 47 The CO 2 utilization route based on CO 2 conversion to solid carbonates involves a complex set of reactions by which CO 2 reacts with Ca, Mg, and/or Fe oxide-bearing phases to yield the corresponding solid carbonate phase. Both gas−solid and aqueous conversion processes have been extensively studied to perform the carbonation reaction.…”