Production of renewable diesel via catalytic deoxygenation of natural triglycerides: Comprehensive understanding of reaction intermediates and hydrocarbons

This study describes an efficient one-step method for the comprehensive analysis of the composition of renewable diesel produced directly from a natural triglyceride, including evaluation of its content of partially deoxygenated species. Previous approaches have been capable of only limited, less detailed hydrocarbon analysis because of their poor ability to separate the middle distillates. Moreover, the complexity and the variety of partially deoxygenated reaction intermediates in a typical renewable green diesel, including alcohols, acids, esters, aldehydes, and ketones, have led to difficulties in analyzing the exact composition and in understanding the reaction pathway. Herein, we propose a novel four-dimensional gas chromatography approach combined with time-of-flight mass spectrometry (GC×GC-TOFMS) that will help us gain a fundamental understanding of the reaction pathways that arise when different catalysts and reaction conditions are used. This information could further help in developing deoxygenation catalysts and processes that are more efficient. Based on the GC×GC-TOFMS analysis, different deoxygenation reaction pathways were proposed to be dominant over various catalysts including Pd, Ni, CoMoS_x, and NiMoS_x under different reaction conditions.