New methods for the preparation of nanoscale nickel phosphide catalysts for heteroatom removal reactions
The removal of heteroatom impurities (S, N, O) from fossil fuel and biomass feedstocks is a critical step in the production of clean-burning transportation fuels. Nickel phosphide (Ni2P) has emerged as a leading candidate material on which to base a new class of catalysts to compete with the long established Ni–Mo and Co–Mo sulfides for hydrotreating of crude oil feedstocks. A recent assessment by researchers at ExxonMobil suggested that a Ni2P catalyst having a 3 nm particle size could compete with a state-of-the-art Co–Mo/Al2O3 catalyst for the hydrodesulfurization (HDS) of a straight-run gas oil feed. This article reviews recent advances in the low-temperature preparation of highly-active, nanoscale Ni2P catalysts.