Effect of Fe and La on the Performance of NiMgAl HT-Derived Catalysts in the Methanation of CO₂ and Biogas

Abstract

Bulk Ni-based catalysts derived from hydrotalcite-type (HT) compounds show enhanced stability in the hydrogenation of CO2 into CH4, in comparison to their supported counterparts. The composition of the parent hydrotalcite determines the Ni loading and particle size, as well as the basicity of the catalysts. In this work, a comparison between the effect of Fe and La on the performance of NiMgAl HT compounds (Ni/Mg/Al = 25/50/25 atomic ratio) calcined at 600 °C is investigated. After a reduction pretreatment at 750 °C, both promoters enhance the activity in the low-temperature range; however, the La-containing catalyst reaches a better CH4 productivity rate at high oven temperature (i.e., 200 L gNi –1 h–1 at 325 °C). Although the formation of the NiFe alloy improves the activity, lanthanum keeps smaller Ni0 particles and provides a higher basicity to the mixed oxide than Fe. The activity of the NiMgLaAl catalyst can be further tailored by increasing the Ni loading from 25.6 wt % (Ni25Mg50La5Al20) to 44.6 wt % (Ni50Mg25La5Al20). Lastly, the feasibility of HT-derived catalysts in the direct methanation of clean biogas is proved.

Boosting Activity and Selectivity of UiO‐66 through Acidity/Alkalinity Functionalization in Dimethyl Carbonate Catalysis

“…The CO 2 ‐TPD profile of UiO‐66 and NH 2 ‐UiO‐66 (Figure 2f and Table S5, Supporting Information) showed two peaks at ≈110 and ≈220 °C, corresponding to weak Lewis alkaline and medium Lewis alkaline, respectively. [ 19 ] It indicated that the Lewis alkaline sites of NH 2 ‐UiO‐66 were more than that of pristine UiO‐66. It was thus clear that Lewis acidity would increase after UiO‐66 was modified with NO 2 , while the functionalization by NH 2 would improve the amounts of Lewis alkaline.…”

Composition Effect on the Formation of Oxide Phases by Thermal Decomposition of CuNiM(III) Layered Double Hydroxides with M(III) = Al, Fe

“…The number of different octahedrally coordinated cations that can be introduced in the brucite-like layers is theoretically unlimited as long as the ionic radius is in the range of 0.65–0.80 Å and 0.62–0.69 Å for the trivalent and divalent cation, respectively, although the most common trivalent Al 3+ is significantly smaller (0.50 Å). However, cations with larger ionic radii and/or higher coordination, such as lanthanides or noble metal cations as well as tetravalent cations (e. g. Zr 4+ , Sn 4+ , and Ti 4+ ), have been introduced in M 2+ M n+ -LDHs or in multicationic LDHs containing a large number of divalent and/or trivalent cations [ 9 , 10 , 11 , 12 , 13 , 14 , 15 , 16 , 17 , 18 , 19 ].…”

Preface for Special Issue on Engineered Methodologies for CO2 Utilization

“…Focusing now on CO 2 transformation using green hydrogen, Tsubaki et al reported the direct conversion of CO 2 to aromatics using a bifunctional zeolite-based catalyst, Herskovitz et al. investigated the process configuration and technoeconomic aspect of CO 2 hydrogenation to renewable liquid fuels, Fan et al reported the conversion of CO 2 to light olefins using metal oxides, Pieta et al discussed the conversion of CO 2 to CO and methane using non-noble-metal-supported catalysts, Wang et al reported the conversion of CO 2 to methanol using a modified Cu/ZnO/Al 2 O 3 catalyst, Ma et al provided a short review on the formation of methanol from CO 2 by direct and indirect hydrogenation pathways, Gonzalez-Velasco et al investigated kinetics, model discrimination, and parameters of CO 2 methanation, Ding et al and Benito et al studied the mechanism of CO 2 methanation and promoter effect on the catalyst performance. For the transformation of CO 2 using chemicals other than green hydrogen, Ateka et al reported the joint conversion of CO 2 with syngas to synthesize light olefins, Liang et al and Sun et al prepared nickel-based catalysts for CO 2 reforming of methane, Jin et al investigated carbon fixation via the gasification of polypropylene and polycarbonate in a CO 2 environment, Song et al revealed mechanistic insights into the promotional effect of CO 2 on propane aromatization, and Liu et al reported enhanced CO 2 decomposition via frosted dielectric barrier discharge plasma .…”