Quantitative synergy between metal and acid centers over the Ni/Beta bifunctional catalyst for methyl laurate hydrodeoxygenation to bio-jet fuel

Abstract

The synergistic effect of metal and acid centers influences performance of bifunctional hydrodeoxygenation (HDO) catalyst significantly. However, seldom work concerning this point has been performed quantitatively. Herein, the Ni/Beta catalysts were prepared for HDO of methyl laurate to bio-jet fuels. The ratios of metal to acid centers (nNi/nA) were used to quantitatively express the synergistic effect and correlated to the HDO performance. The transformation of methyl laurate mainly stagnates at fatty acid over the mono-functional catalyst (nNi/nA = 0), while the acid centers are indispensable for the efficient transformation of methyl laurate at relatively mild reaction conditions. The TOF and selectivity to C11 and C12 alkanes increase and then keep constant with the increasing nNi/nA. The turning point at the nNi/nA of 0.67 implies that one nickel center over the Ni/Beta catalyst can balance ca. 1.5 acid centers in the HDO of methyl laurate. Besides, the higher nNi/nA favors the HDO reaction pathway compared with the decarbonylation or decarboxylation ones. It increases the selectivity to C12 alkanes and improves efficiency of atomic utilization during the hydrodeoxygenation of methyl laurate. This work provides a deeper insight into the quantitative synergy of active sites over the bifunctional HDO catalyst for production of bio-fuels.