Biogenic hydroxyapatite as novel catalytic support for Ni and Cu for the water-gas shift reaction

Biogenic hydroxyapatite (NHAp) was prepared by calcination of waste pork bones and investigated as catalytic support for Ni and Cu metals in the water-gas shift (WGS) reaction. Part of the doped Cu was ion exchanged with Ca ions in the NHAp structure. Also, XPS data showed that after Cu doping, nickel d-hole density increased due to adjacent Cu atoms. Upon reduction, Ni-Cu alloying was detected. For an ideal mixture (CO/H2O: 1/2 in vol%), the monometallic Cu assay was WGS inactive, whereas 10Ni/NHAp was the most active. However, under reformer outlet stream conditions (CO/H2O/CO2/H-2/He = 5/46/4/31/14, in vol%), the catalyst 10Ni/NHAp showed negative H-2 yield (net hydrogen consumption), whereas selectivity and yield to H-2 by Cu-doped bimetallic catalysts reached up to 93% and 26%, respectively. Interestingly, the band-gap energy of these catalysts decreased in line with methane suppression capability (10Ni/NHAp >> 7.5Ni2.5Cu/NHAp > 2.5Ni2.5Cu/NHAp > 10Cu/NHAp). Long duration catalytic tests revealed that NHAp derived from pork bone can provide good stability for the WGS reaction, with negligible carbon deposition. [GRAPHICS]

Automated summary

Biogenic hydroxyapatite (NHAp) supported Ni and Cu metals were studied for water-gas shift (WGS) reaction catalysis. Cu doping enhanced Ni d-hole density, forming Ni-Cu alloying. Cu-doped bimetallic catalysts exhibited higher activity and H-2 yield under reaction conditions.