Phosphorus-loaded alumina supported nickel catalysts for CO2 hydrogenation: Ni2P/Ni5P12 drives activity.

[Display omitted] • A series of 5 wt% NiO-xP-Al 2 O 3 with different phosphorus loading contents (x = 0, 5, 15 and 20 wt%) were prepared by a modified sol-gel method. • All the catalysts reach the highest conversion at 600 °C with 61.54 %, 62.89 %, 63.88 % and 66.13 % respectively for 5 wt% NiO-Al 2 O 3 , 5 wt% NiO-5P-Al 2 O 3 , 5 wt% NiO-15P-Al 2 O 3 and 5 wt% NiO-20P-Al 2 O 3 catalysts. • Ni/NiO/Ni 2 P/Ni 5 P 12 /AlPO 4 interfacial species were detected on the surface as active species on the used catalysts by X-ray photoelectron spectroscopy. • The formation ratio of the metal-phosphide is relatively low ∼3−5 %, and this atomic concentration is decreasing with the rising of the phosphate content. However, the nickel enrichment in the surface layer presumable in Ni 2 P/Ni 5 P 12 form is very likely according to the P 2p spectra and the authors assume that could be responsible for the enhanced catalytic activity. A series of 5 wt% NiO-xP-Al 2 O 3 with different phosphorus loading contents (x = 0, 5, 15 and 20 wt%) were prepared by a modified sol-gel method. A significant promotional effect of phosphorus on NiO-Al 2 O 3 in CO 2 hydrogenation is observed. All the catalysts reach the highest conversion at 600 °C with 61.54 %, 62.89 %, 63.88 % and 66.13 % respectively for 5 wt% NiO-Al 2 O 3 , 5 wt% NiO-5P-Al 2 O 3 , 5 wt% NiO-15P-Al 2 O 3 and 5 wt% NiO-20P-Al 2 O 3 catalysts. Ni/NiO/Ni 2 P/Ni 5 P 12 /AlPO 4 interfacial species were detected on the surface as active species on the used catalysts by X-ray photoelectron spectroscopy. The formation ratio of the metal-phosphide is relatively low ∼3−5 %, and this atomic concentration is decreasing with the rising of the phosphate content. However, the nickel enrichment in the surface layer presumable in Ni 2 P/Ni 5 P 12 form is very likely according to the P 2p spectra and the authors assume that could be responsible for the enhanced catalytic activity. [ABSTRACT FROM AUTHOR]