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The influence of Yb on Ni(20 wt%)/γ-Al 2 O 3 catalysts (prepared via a sol–gel method) for use in the dry reforming of methane was investigated. It was found that the addition of low quantities of Yb (1–2 wt%) led to significant increases in catalytic activity and catalyst stability, and the production of H 2 and CO at a ratio close to unity (∼0.95). Higher levels of Yb doping (3–8 wt%) did not achieve similar increases in activity as those observed in the lower level doped catalysts. Based on characterisation studies conducted on the catalysts before and after testing it was found that the catalyst with a low level of Yb (2 wt%) had the smallest average Ni particle size, narrowest particle size distribution and highest ease of reducibility (based on Temperature Programmed Reduction analysis). Analysis of the catalysts after testing showed that the catalyst with 2 wt% Yb also experienced the lowest level of carbon deposition and contained a high degree of graphitised carbon. The results obtained indicate that doping of Ni-Al 2 O 3 catalysts with a select amount of Yb can give rise to a catalyst with excellent properties for use in the dry reforming of methane and that Yb can have a significant role in controlling the size/mobility of Ni nanoparticles produced via reduction of NiO.

Nanostructured Ni-incorporated mesoporous alumina (MAl) materials with different Ni loading (7, 10 and 15 wt %) were prepared by a template assisted hydrothermal synthesis method and tested as catalysts for CO2 reforming of methane under different conditions (nickel loading, gas hourly space velocity (GHSV), reaction temperature and time-on-stream (TOS)). The most active catalyst tested (Ni(10 wt%)-MAl) showed a very high stability over 200 h compared to a Ni(10 wt%)/γ-Al2O3 prepared using a co-precipitation method which had a significant loss in activity after only ∼4 h of testing. The high stability of the Ni-MAl materials prepared by the template assisted method was due to the Ni nanoparticles in these catalysts being highly stable towards migration/sintering under the reaction conditions used (800 °C, 52,000 mL h−1 g−1). The low susceptibility of the Ni nanoparticles in these catalysts to migration/sintering was most likely due to a strong Ni-support interaction and/or active metal particles being confined to the mesoporous channels of the support. The Ni-MAl catalysts also had significantly lower amounts of carbon deposited compared to the catalyst prepared using the co-precipitation method.

Successful synthesis of stable MFe2O4 nanoparticles@C has been realized by applying the novel concept of using levulinic acid possessing carboxyl and carbonyl groups to facilitate the interaction with metal ions (M(2+) and Fe(3+)) and the carbon source (phloroglucinol) in the sol-gel polymerization method. All the samples have been characterized by XRD, SEM, FT-IR, TEM, HRTEM, ICP-AES, CHNS, and N2 adsorption-desorption, and were studied for their performance towards hydrogenation reaction of styrene. Out of three samples NiFe2O4 gave excellent selective hydrogenation activity of styrene to ethyl benzene (100% conversion and 100% selectivity). Optimal production of ethyl benzene over NiFe2O4 nanoparticles@C has been established at 80 °C reaction temperature after 24 h reaction time under 40 bar hydrogen pressure.