Towards conversion of octanoic acid to liquid hydrocarbon via hydrodeoxygenation over Mo promoter nickel-based catalyst

• We reported the details of octanoic acid HDO over Ni–ZrO2.
• Mo as additive improved the acid conversion and selectivity of octane.
• H2–TPD and SEM were used to verify the effect of introducing of Mo.
• A reasonable reaction mechanism of octanoic acid conversion was proposed.
• The optimal acid conversion was 100%, with a maximum octane yield of 77.07%.

In the current paper, Mo doped Ni–ZrO2 catalyst was prepared, which was used for the liquid hydrocarbon from conversion of octanoic acid via hydrodeoxygenation (HDO). The experimental results showed that the reaction product is mainly C8 alkane with a yield of 77.07% when 10Mo/Ni–ZrO2 was used as the catalyst compared with the major product of C7 alkane over Ni–ZrO2 catalyst with a yield of 69.68%. The introduction of Mo into the Ni–ZrO2 channel generated in Mo/Ni–ZrO2 samples was characterized by nitrogen sorption, TEM, XRD, TPR, and TPD. The results demonstrated that the doping Mo particles to the Ni–ZrO2 catalyst resulted in the transformation of ZrO2 support from cubic form (c-ZrO2) to monoclinic form (m-ZrO2), and the improvement of the hydrogen adsorption capacity and acid property of the catalyst. Thus, the doping of Mo favored the dehydration–hydrogenation reactions of octanol intermediate which in turn facilitated octanoic acid HDO to C8 alkane. Therefore, a novel approach to octanoic acid HDO to C8 alkane is introduced, which provides a basis as well as technical parameters for its further industrialization.

Figure optionsDownload high-quality image (176 K)Download as PowerPoint slideWhen no Mo content was present, the major product of octanoic acid conversion was C7. Adding certain Mo particles to the Ni–ZrO2 catalyst could not only improve the octanoic acid conversion but was also beneficial to the generation of C8 alkane distinctly. Meanwhile, the selectivity of C8 had an increasing trend with the Mo content till 10 wt%, at which the C8 selectivity reached to its maximum of 77.07% with a complete acid conversion. When the Mo content increased to 15 wt%, the octanoic acid conversion as well as C8 selectivity decreased sharply. This could be attributed to that an excess of Mo particles would cover the Ni active sites as well as anionic vacancies on the surface of ZrO2 support.The different product distributions suggested different octanoic acid conversion mechanisms prevailed over the Ni–ZrO2 and Mo/Ni–ZrO2 catalysts.