Importance of size and distribution of Ni nanoparticles for the hydrodeoxygenation of microalgae oil

Improved synthetic approaches for preparing small-sized Ni nanoparticles (d=3 nm) supported on HBEA zeolite have been explored and compared with the traditional impregnation method. The formation of surface nickel silicate/aluminate involved in the two precipitation processes are inferred to lead to the stronger interaction between the metal and the support. The lower Brønsted acid concentrations of these two Ni/HBEA catalysts compared with the parent zeolite caused by the partial exchange of Brønsted acid sites by Ni²⁺ cations do not influence the hydrodeoxygenation rates, but alter the product selectivity. Higher initial rates and higher stability have been achieved with these optimized catalysts for the hydrodeoxygenation of stearic acid and microalgae oil. Small metal particles facilitate high initial catalytic activity in the fresh sample and size uniformity ensures high catalyst stability. The small matter of size: Nearly 5-8-fold enhancements of initial rates and improved recyclability have been achieved with Ni/HBEA catalysts, prepared by improved synthesis techniques, on the hydrodeoxygenation of stearic acid and microalgae oil. The average size and uniformity of Ni particles are crucial for maintaining the highly active and stable catalyst. The small metal sites facilitate high initial rates and the good uniformity ensures high catalyst stability (see figure).