Effect of Temperature and Reaction Time on Triolein Deoxygenation over Niobium Phosphate

Abstract

Growing concerns regarding climate change and the depletion of fossil fuel resources have intensified the search for renewable and sustainable energy sources. In this context, drop-in biofuels have attracted significant attention because of their physicochemical properties comparable to those of conventional fossil fuels. Catalytic deoxygenation of triglycerides is one of the main routes for producing drop-in biofuels, owing to the availability of lipid-based feedstocks and the potential to produce hydrocarbons within diesel and aviation fuel ranges. This study investigates niobium phosphate (NbOPO4) as an alternative catalyst for triolein deoxygenation. Batch experiments were performed at 250, 300, and 350 degrees Celsius, with reaction times ranging from 0.5 to 3.0 h, an initial H2 pressure of 10 bar at room temperature, and a catalyst loading of 10 wt%. At 350 degrees Celsius, a degree of deoxygenation of approximately 99% was achieved within 30 min, with a product distribution comprising 54-65% linear hydrocarbons, 24-32% branched hydrocarbons, and 8-14% aromatic compounds. The reaction proceeded through HDO, DCO2, and DCO pathways, leading predominantly to n-octadecane and n-heptadecane. Under the investigated conditions, niobium phosphate showed substantial catalytic activity for triolein deoxygenation and promoted the formation of renewable hydrocarbons with different degrees of branching. Overall, the results demonstrate the potential of NbOPO4 for triglyceride deoxygenation under comparatively moderate hydrogen-pressure and reaction-time conditions, highlighting its potential as an alternative to conventional metal-based catalysts for drop-in biofuel production.