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This paper reports the usage ratio of TEOS and Zr(OBu) 4 on the formation of Ni@ZrO 2 yolk-shell for dry reforming of methane. From XPS analysis, the ZrO 2 hollow shell texture is demonstrated to be [TEOS]/[Zr(OBu) 4 ] dependent due to different sizes of SiO 2 produced. It found that an adequate ratio of [TEOS]/[Zr(OBu) 4 ] improves the catalytic conversion of dry reforming of methane. It (Ni@ZrO 2 -SiZr-7.7) shows 90% conversion for CH 4 and 93% for CO 2 at a WHSV of 72,000 mLg cat −1h−1 for 50 h at 800 °C with TOF CH4 of 8.7 s−1. It proposed that the changes in surface Si/Zr and gradual interconnecting pores contributed to its activity and stability. These finding's potential to be utilized in other high-temperature reactions. [ABSTRACT FROM AUTHOR]

The dry reforming of methane is a potential reaction that converts methane and carbon dioxide to syngas while mitigating the two greenhouse gases. Challenges for this reaction include sintering and severe carbon deposition. This paper reports a post-treatment strategy to develop Ni@hollow meso-SiO 2 (Ni@HMS) catalyst from the existing Ni@SiO 2 core-shell structure by utilizing the mechanism of etching and re-deposition of silica in mild alkaline solution with CTAB as a stabilizer. The varied post-treatment temperature changed the properties of Ni@HMS and demonstrated high catalytic performance compared to Ni@SiO 2. The results from TEM and XPS showed the Ni particles were confined inside the mesoporous SiO 2 shell and inhibit Ni particle mobility. The catalysts exhibited high conversion of methane (>80%) and carbon dioxide (>90%) for 50 h at 800 °C and WHSV of 54 000 mL g cat −1h−1 with high TOF CH4 of 7.08 s−1. Image 1 • Ni@hollow meso-SiO 2 was synthesized under mild alkaline solution with CTAB. • Surface area enhanced with increasing post-treatment temperature. • Ni dispersion maintained during the post-treatment. • Ni@HMS-70 has TOF CH4 of 7.08 s−1 and H 2 STY of 2.53 × 10−4 mols−1g cat −1. [ABSTRACT FROM AUTHOR]

This paper reports the varying water-to-surfactant (ω) ratio in reverse microemulsion on the development of Ni encapsulation in bulk SiO 2 catalyst for dry reforming of methane. From XRD and TEM analyses, the Ni particle size depends on the water-to-surfactant ratio. It found that an optimized ratio of ω improves the catalytic activity for the dry reforming of methane. The catalyst (Ni-SiO 2 -ω23) shows 70% CH 4 conversion and 78% CO 2 conversion at 700 °C and WHSV of 72000 mLg cat −1h−1 operating for 50 h with TOF of 12.6 s−1. It is highly anticipated that the increased fraction of 2:1 nickel phyllosilicate and small Ni particle size contributed to its improved catalytic activity corresponding to the ω ratio. Also, a higher ω value can resist carbon formation in the catalysts, characterized by XRD, TGA, Raman, XPS, and TEM. These results were encouraging that could be applied in similar high-temperature reactions. [Display omitted] • Different sizes of Ni nanoparticles synthesized via ω ratio. • Encapsulation of Ni in bulk grains of SiO 2 validated by ICP-MS, XPS, and TEM. • Smaller Ni nanoparticles and increased 2:1 nickel phyllosilicate with high ω ratio. • Synthesized encapsulated Ni-SiO 2 with higher ω ratio capable to anti-coking. • Optimized catalyst exhibited high TOF CH4 of 12.6 s−1 at 700 °C for 50 h. [ABSTRACT FROM AUTHOR]