Embedded Structure of Ni@PSi Catalysts for Steam Reforming of Methane

Abstract

Embedding Ni nanoparticles (NPs) into supports has been widely accepted as one of solutions for Ni confinement. Herein, we have adopted a method of preparing well-confined Ni NPs by precisely adjusting the reduction temperature of nickel contained phyllosilicates (PSi) materials to obtain Ni@PSi catalysts. H 2 reduction at 600 °C for Ni-PSi precursor was optimized to build the embedded structure with uniform Ni NPs (ca. 3.0 nm) incorporated into the well-maintained PSi structure. Such structure not only endowed the highest reaction rate for steam reforming of methane (SRM), but kept the stability well under the harsh reaction conditions of SRM. Either too high (850 °C) or too low (400 °C) reduction temperature which could not form such embedded structure led to a quick deactivation due to obvious sintering of Ni and coke deposition. The present study provides a more effective way of keeping Ni NPs from sintering in SRM.

Dry Reforming of Methane over Rare-Earth Metal Oxide Ni–M–Al (M = Ce, La) Catalysts

“…The normalized carbon content per exposed amount of nickel increased with increasing nickel particle size in the spent catalyst, except for 15Ni–35La (Figure b). Analogous results showing high coke formation with large Ni particles for Ni supported on the silica catalyst in steam reforming of methane at 800 °C were obtained in refs and as well as in DRM over Ni–CeO 2 modified with different metals . Also, in DRM, more coke was formed over larger Ni particles .…”

“…However, TOFs were increasing with increasing metal particle size and reaching the maximum for 15Ni–15La–20Al, while for 20 nm Ni particles observed in 15Ni–35La, the TOF value dropped. In addition, structure sensitivity for methane transformation was also observed, where a volcano-type curve to the methane turnover frequency was obtained with increasing Ni particle size …”

“…In addition, structure sensitivity for methane transformation was also observed, where a volcano-type curve to the methane turnover frequency was obtained with increasing Ni particle size. 63 The deactivation rate was the highest for 15Ni−15La−20Al (Table 7), which contained the second-largest metal particle in the spent catalyst (Figure 9b and Table 2). The normalized carbon content per exposed amount of nickel increased with increasing nickel particle size in the spent catalyst, except for 15Ni−35La (Figure 9b).…”

Photothermal steam reforming of methane over silica-supported nickel catalysts with temperature gradients

“…Recently, the fabrication of small and uniform Ni nanoparticles via the decomposition of Ni phyllosilicates (Ni PSs) has been reported as an effective method for enhancing catalytic activity in thermal SRM (TSRM). [37][38][39] Thus, this catalyst preparation technique would be effective in developing highly-active catalysts for PTSRM. Moreover, the photothermal catalytic system provides inhomogeneous temperature distribution under concentrated light irradiation, and the temperature gradient affects the catalytic activity.…”