NiWS/Al2O3 hydrotreating catalysts prepared with 12-tungstophosphoric heteropolyacid and nickel citrate: Effect of Ni/W ratio

- Ni-PW/Al2O3 catalysts were prepared with H3PW12O40 and nickel citrate.
- Average length and stacking number of NiWS increased with Ni/W ratio.
- Catalysts with 0.33-0.45 of Ni/(Ni + W) produced maximal conversions in HDS, HYD and HDN.
- The highest TOF values were achieved at moderate Ni/(Ni + W) ratio equal to 0.24.
- Saving TOF numbers at high Ni/(Ni + W) was caused by spillover effect induced by NiS.