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Porous Ni@SiO core‐shell catalysts (Ni@SiO2‐xC10) were modified by selective etching in a mild alkaline solution using decyltrimethylammonium bromide (C10TAB). The effects of C10TAB concentration on the Ni@SiO2 nanoparticles were explored and used in the dry reforming of methane. It can change the physicochemical properties of Ni@SiO2, and the modified Ni@SiO2‐xC10 exhibits better catalytic performance than Ni@SiO2. TEM, N2‐isotherm, and H2‐TPR results show that Ni@SiO2‐xC10 modified with a sufficient concentration of C10TAB has a mesoporous core‐shell structure, which not only increases the pore volume and surface area but also enhances the metal‐support interaction; XPS and TEM results indicate that Ni nanoparticles are confined within the mesoporous core‐shell, which inhibits the migration of Ni nanoparticles at high temperature. The Ni@SiO2‐2C10 catalyst showed optimal catalytic performance under reaction conditions of 800 °C, N2 : CH4 : CO2=1 : 1 : 1, and WHSV of 126000 mLgcat−1 h−1 with increased conversion of CH4 (>79 %) and CO2 (>84 %) within 50 h. [ABSTRACT FROM AUTHOR]

Carbon-coated Fe3O4 nanoparticles with tunable size were fabricated through a facile one-pot solvothermal method and employed as catalysts for Fischer–Tropsch (FT) synthesis to optimize the product distribution of hydrocarbons. Each spherical nanoparticle (Fe3O4@C) was observed to consist of a core–shell structure with an Fe3O4 core and a carbon shell. Furthermore, the Fe3O4 particle size can be effectively tailored by altering the initial dosage of glucose during catalyst preparation. Fe3O4@C with a suitable structure exhibited notable catalytic activity (CO conv. over 98%), high C5–C11 selectivity (46.6%) and superior stability in the FT synthesis. It was proposed that Fe3O4@C with a small particle size facilitated the formation of more active sites, which are responsible for the enhanced catalytic activity. However, the increase in particle and pore size promoted the selectivity towards C5+ hydrocarbons and lower olefins. This may provide a novel route to directly synthesize gasoline fuels during FTS. [ABSTRACT FROM AUTHOR]

Fischer-Tropsch synthesis (FTS), as an alternative process for producing liquid fuels from bio-syngas, is receiving renewed interest for both industrial and academic applications. A novel carbon-encapsulated Fe 3 O 4 nanocatalyst is designed to optimize the product distribution of hydrocarbons. Several techniques such as XRD, H 2 -TPR, BET, XPS, LRS, SEM and TEM are used to characterize the catalyst samples. The characterization results indicated that combination of glucose and iron species led to the formation of carbon-encapsulated Fe 3 O 4 nanoparticles (Fe 3 O 4 @C), and the increasing glucose content in the catalysts resulted in the decrease of Fe 3 O 4 @C nanoparticle sizes. Fe 3 O 4 @C with smaller particle sizes provided more surface amounts of iron species, which facilitated the reduction of iron oxides and formation of active iron sites. However, the excess addition of glucose resulted easily in the formation of more carbon deposition on the surface of Fe 3 O 4 @C. Compared to the traditional Fe 2 O 3 catalyst, the Fe 3 O 4 @C catalyst showed excellent catalytic activity and higher selectivity of gasoline products. Especially, decreasing nanoparticle sizes for the carbon-encapsulated Fe 3 O 4 catalysts improved obviously the catalytic activity and increased the selectivity of C 2-4 hydrocarbons. [ABSTRACT FROM AUTHOR]

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 -1 h -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., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2021 Elsevier Inc. All rights reserved.)