Partial Oxidation of Bio-methane over Nickel Supported on MgO–ZrO2 Solid Solutions

Abstract

Syngas can be produced from biomethane via Partial Oxidation of Methane (POM), being an attractive route since it is ecofriendly and sustainable. In this work, catalysts of Ni supported on MgO–ZrO2 solid solutions, prepared by a one-step polymerization method, were characterized by HRTEM/EDX, XRD, XPS, H2-TPR, and in situ XRD. All catalysts, including Ni/ZrO2 and Ni/MgO as reference, were tested for POM (CH4:O2 molar ratio 2, 750 ºC, 1 atm). NiO/MgO/ZrO2 contained two solid-solutions, MgO–ZrO2 and NiO-MgO, as revealed by XRD and XPS. Ni (30 wt%) supported on MgO–ZrO2 solid solution exhibited high methane conversion and hydrogen selectivity. However, depending on the MgO amount (0, 4, 20, 40, 100 molar percent) major differences in NiO reducibility, growth of Ni0 crystallite size during H2 reduction and POM, and in carbon deposition rates were observed. Interestingly, catalysts with lower MgO content achieved the highest CH4 conversion (~ 95%), high selectivity to H2 (1.7) and CO (0.8), and low carbon deposition rates (0.024 g carbon.gcat−1 h−1) with Ni4MgZr (4 mol% MgO) turning out to be the best catalyst. In situ XRD during POM indicated metallic Ni nanoparticles (average crystallite size of 31 nm), supported by MgO–ZrO2 solid solution, with small amounts of NiO–MgO being present as well. The presence of MgO also influenced the morphology of the carbon deposits, leading to filaments instead of amorphous carbon. A combustion-reforming mechanism is suggested and using a MgO–ZrO2 solid solution support strongly improves catalytic performance, which is attributed to effective O2, CO2 and H2O activation at the Ni/MgO–ZrO2 interface.

Green hydrogen Production from the oxidative reform of clean biogas over Ni/MgO-Nb2O5 catalysts

“…Catalysts must have adequate properties to activate CO2 and O2 molecules; for instance, some solid solutions based on ZrO2 have excellent properties to activate CO2 and O2 during methane reforming and partial oxidation of methane reactions [5]. In the case of NiO-MgO-Nb2O5 catalysts, MgO may be favoring the activation of CO2, as previously reported in [26], [27] for NiO-ZrO2 catalyst in Dry reforming of methane.…”

“…Figure 1b shows that there is a continuous displacement of the main peak of NiO (or NiO-MgO) towards larger Bragg angles, indicating a contraction in the lattice parameter. This contraction would indicate that Ni 2+ ions entered the crystal lattice of MgO replacing some Mg 2+ ions; as an effect of the formation of the NiO-MgO solid solution, a fact that would be reasonable since the ionic radius of Ni 2+ (0.55 Å) is slightly smaller than that of Mg 2+ (0.57Å) [5], [12], [15]. Upon these results, it is possible to affirm that this solid solution was formed in all samples that contain the three oxides: NiO/MgO/Nb2O5 since the displacement of the main peak of NiO is present in the XRD pattern of all these samples.…”

“…Syngas can then go through the Water-Gas Shift reaction (WGSR, to give a mixture of H2 and CO2) and subsequently undergo an absorption process (with amines to remove CO2) to purify hydrogen, which can be used by industry for several applications, it can also even be used as fuel in fuel cells. [5].…”

Hydrogenolysis of Glycerol over NiCeZr Catalyst Modified with Mg, Cu, and Sn at the Surface Level

“…The Zr 3d core-level spectra for all calcined solids ( Figure S4 in the Supplementary Materials ) presented a doublet at approximately 183.05 eV and 185.5 eV and corresponded to the Zr 3d spin-orbit splitting components (Zr 3d 5/2 and Zr 3d 3/2 ) of Zr 4+ [ 55 , 56 ]. Upon the impregnation of Me, the Zr 3d peaks upshifted in their BE, indicating that the chemical nature of the Zr 4+ species in these materials differed from that in the parent NiCeZr [ 57 ]. Among the three dopants used, Sn caused the largest shift, suggesting that the strongest interaction occurs between Zr and Me.…”

Enhanced Mass Activity and Durability of Bimetallic Pt-Pd Nanoparticles on Sulfated-Zirconia-Doped Graphene Nanoplates for Oxygen Reduction Reaction in Proton Exchange Membrane Fuel Cell Applications

“…The preservation of the graphitic structure of the carbon is advantageous in the preparation of an electrocatalyst because it maintains the conductivity of the support materials. Besides the characteristic peaks of the graphite and Pt construction, some additional peaks at 2θ of 29.95° and 31.69° with the surfaces of −111 and 111 [64][65][66][67][68][69] were found in the nanocomposite, which is related to the ZrO2 nanocrystals used in the composition of the catalyst. The average size of the Pt-Pd nanoparticles was evaluated from the Debby-Scherrer formulation using the full width at half maximum (FWHM) of the (111) plane.…”