The formation and transformation of hexadecanal influence on reaction pathway and activity in the palmitic acid hydrodeoxygenation over mesoporous ETS-10 supported Ni catalyst

Abstract

Mesoporous ETS-10 zeolites supported Ni catalysts (Ni@NaMETS-10 and Ni@HMETS-10) were applied in the hydrodeoxygenation (HDO) of palmitic acid to investigate the formation and transformation pathways of hexadecanal (HAL) and reaction activity. Experiment results verified that HAL was an initial product in the HDO reaction under 0.1 MPa H2 pressure, and Ni@HMETS-10 exhibits higher activities (robs,1=2.55×10−4 mol kg−1 s−1, robs,2= 6.85×10−3 mol kg−1 s−1) than Ni@NaMETS-10 (robs,1=1.59×10−4 mol kg−1 s−1, robs,2=5.74×10−3 mol kg−1 s−1) due to the presence of Brönsted acid sites and highly dispersed Ni particles. At high H2 pressure (4.0 MPa), the acid-base properties of the support affected the transformation of HAL and the reaction pathways. The abundant Lewis basic sites on Ni@NaMETS-10 can promote the decarbonylation of the HAL and the HDCO route are dominate. Brönsted acid and Ni sites on Ni@HMETS-10 synergistically catalyzed the deoxygenation of palmitic acid via two parallel HDH2O and HDCO routes with a higher reaction rate (1.42×10−3 mol kg−1 s−1) than Ni@NaMETS-10 (1.31×10−3 mol kg−1 s−1). The reaction rate constants of each step in reaction routes on both catalysts were supplemented.