110th Anniversary: Dry Reforming of Methane over Ni- and Sr-Substituted Lanthanum Zirconate Pyrochlore Catalysts: Effect of Ni Loading

Abstract

Pyrochlores are thermally stable materials that can be doped with a metal to produce active catalyst for dry reforming of methane (DRM). La 1.95 Sr 0.05 Zr 1.904 Ni 0.096 O 7−d (LSNZ1) and La 1.95 Sr 0.05 Zr 1.44 Ni 0.56 O 7−d (LSNZ6), with 1 and 6 wt % Ni loading at Zr site, respectively, were investigated for DRM. XRD of fresh catalysts confirmed the formation of pyrochlore structure. Also, the presence of the La 2 NiZrO 6 perovskite phase and NiO phase indicated low substitution of Ni in the pyrochlore structure. TPSR and DRM long runs carried out at 900 °C and 45 h time on stream confirmed that LSNZ6 was more active than LSNZ1, which is attributed to higher Ni content and dispersion of Ni in LSNZ6. In both the catalysts, the pyrochlore structure was stable during the reaction, but the perovskite phase was reduced to respective metal oxides. No carbon deposition was observed on both the catalysts during 900 °C DRM runs for 45 h. Also, no sintering of catalyst was observed from XRD and TPR.

One-Step Synthesis of Highly Active and Stable Ni–ZrOx for Dry Reforming of Methane

“…CO 2 reforming of methane (DRM) could not only utilize CO 2 and CH 4 , which are the main greenhouse gases, but also produce synthesis gas (a mixture of CO and H 2 ). The latter can be used in the synthesis of high-value chemicals. − Furthermore, syngas with a H 2 /CO ratio close to unity is attractive for the synthesis of fuels, for example, in Fischer–Tropsch synthesis over iron-based catalysts. − However, side reactions could occur during the DRM reaction, such as the reverse water–gas shift (RWGS) reaction, methane cracking, and CO disproportionation, resulting in the deactivation of the catalyst and/or lower H 2 /CO molar ratio. Thus, many research studies have paid much attention to enhance both high catalytic activity and stability of the used catalysts.…”

Improved Effect of Fe on the Stable NiFe/Al2O3 Catalyst in Low-Temperature Dry Reforming of Methane

“…Syngas derived from the renewable biomass process has attracted tremendous interests for the generation of various value-added chemicals and fuel, yet biogas inevitably contains carbon dioxide (CO 2 ) and methane (CH 4 ) during the biomass gasification. , Therefore, there is a growing concern on converting the two greenhouse gases to syngas as a desirable procedure for the upgrading of biomass-derived syngas. Dry reforming of methane (DRM) has been regarded as an alternative route for the effective utilization of CO 2 and CH 4 to the syngas. − Generally, DRM reaction requires high reaction temperature (>650 °C) because of its endothermic characteristic. Besides noble-based catalysts, Ni-based catalysts exhibit comparable activity and selectivity to H 2 ; whereas the sintering of Ni nanoparticles (NPs) (low Tammann temperature of Ni) and coke deposition (CO and CH 4 dissociation) quickly deactivate the catalyst during the high-temperature reaction.…”

Design of Ni‐substituted La2(CeZrNi)2O7 Pyrochlore Catalysts for Methane Dry Reforming

“…The high-temperature peaks around 490 °C can be attributed to the reduction of Ni exsolved from the La 2 NiZrO 6 perovskite phase for LNZ1C0 and LaNiO 3 perovskite phase for others. [33,39] Besides, for all catalysts, peak areas around 490 °C are higher than others, which means that most NiO particles are reduced at this temperature and most Ni particles are exsolved from the perovskite phase. As shown in Figure 5, with the sequence of LNZ1C0, LNZ3C1, LNZ1C1, LNZ1C3 and LNZ0C1, peaks around 490 °C have a positive shift first, to the highest 521 °C for LNZ3C1, and then gradually shift to lower temperature.…”