Hydrodeoxygenation (HDO) of oleochemical waste oil into paraffins using iron molybdate (Fe-Mo-O) catalyst

The hydrodeoxygenation (HDO) of 1-dodecanol (C12 fatty alcohol) in oleochemical waste oil was investigated in a continuous fixed-bed reactor using Fe-Mo-O catalyst between 200-300°C, 10-20 bars, and at fixed GHSV of 5121 hr -1. The characterization of the product components was analyzed by GC-MS and further quantified by GC-FID to evaluate the effect of temperature and pressure on the HDO of 1-dodecanol to paraffin such as dodecane and lower carbon number of hydrocarbons. The reaction temperature is the most critical operating parameter that affects the performance of the HDO reaction. Conversion of 1-dodecanol increased up to 98.5% with increasing reaction temperature, while at 250°C, the dodecane selectivity was the highest. Two distinct HDO pathways were distinguished: dehydration-hydrogenation (Path 1) and dehydrogenation-decarbonylation/decarboxylation (Path 2). The high temperature and low pressure of the HDO promoted Path 2 route to produce paraffin with a lower carbon number from the reactant. The selectivity of dodecane was low, probably due to the cracking process that occurred at 300°C. The conversion of 1-dodecanol decreased with the increasing pressure, while dodecane's production rate follows the reverse trend of the conversion. High pressure of HDO promoted Path 1 route due to the higher selectivity of dodecane. In conclusion, the optimal temperature and pressure for HDO of oleochemical waste oil over Fe-Mo-O catalyst are 250°C and 20 bars, which gave the highest conversion towards dodecane and C12 paraffin.