Oxygen functionality and chain length effects in HDO: Impact of competitive adsorption on reactivity

The unavoidable and significant impact of compounds with different oxygen functionalities and carbon number on each other in hydrodeoxygenation (HDO) has been experimentally assessed over NiMo and CoMo catalysts in a wide temperature range from 100 °C to 350 °C, at a total pressure of 6 MPa, a feed to catalyst ratio of 1.22 goxygenate gcat−1h−1 and a concentration of 1.5 wt% of each oxygenated compound in n-decane. Overall, the model component conversion over the NiMo catalyst was higher than that over the CoMo catalyst. Compounds with an aldehyde functionality exhibited higher reactivity compared to compounds of the same chain length with a carboxylic acid or an alcohol functionality. The presence of carboxylic acids in feed mixtures along with aldehydes and aromatic oxygenates, shifted the conversion of the latter two to higher temperatures. This behavior could be attributed to competitive adsorption effects between the components with different functionalities and chain lengths.