The Effect of Calcination Temperature on the Properties and Hydrodeoxygenation Activity of Ni2P Catalysts Prepared Using Citric Acid

The effect of calcination temperature on the preparation of unsupported high surface area Ni2P catalysts, synthesized by adding citric acid (CA) to an aqueous solution of nickel nitrate and diammonium hydrogen phosphate, is reported. The addition of CA led to increased surface area, decreased particle size, and increased CO uptake of the reduced Ni2P However, increases in the Ni2P-CA calcination temperature from 773 to 823 and to 973 K led to a deterioration in the catalyst properties. All Ni2P catalysts deactivated following the hydrodeoxygenation (HDO) of 4-methylphenol (4-MP) at 623 K and 4.4 MPa. The deactivation was due to coking and was modeled by an exponential decay law. All Ni2P catalysts had similar deactivation parameters, indicating the loss in activity was due to C deposition on similar sites. The Ni2P-CA catalysts, with crystallite size in the range of 34-50 nm, had comparable initial TOFs, indicating that the HDO of 4-MP was structure insensitive over Ni2P catalysts of this size.