Preparation And Catalytic Properties Of Hydrodeoxygenation Catalysts For The Hydrodeoxygenation Of Oxygen-containing Model Componds

With the problem of using more heavy crude oil, the oil derived from Coal and biomass can be an ideal substitute energy. However, the high oxygen content of primary products which derived from the synthesis oils greatly hindered its widespread use, because of its low heat combustion, poor thermal stability, easy polymerization and influence on the catalysts which used in the oil depth refining process. To solve this problem, it's crucial to select a suitable hydrogenation catalyst for hydrodeoxygenation to improve the oil quality. In this paper, activated alumina carrier was modified by different methods, nano-alumina with large pore volume and pore diameter was prepared by azeotropic distillation-homogeneous precipitation, and a series of nano-ZrO₂/Al₂O₃ composite support with different Zr content were prepared by ultrasonic co-precipitated method. Furthermore, a series of CoMo-based catalyst supported on these carriers and amorphous boron molybdenum oxides catalyst were prepared, Meanwhile, the supports and catalysts were characterized by BET, XRD, SEM, SEM-EDS, XPS, FTIR, Py-FTIR, TGA and the hydrodeoxygenation performances of the catalysts were tested with phenol as the model compound.The results showed that the Al₂O₃ and ZrO₂/Al₂O₃ composite supports have greater specific surface area, pore volume and concentrated pore size distribution. ZrO₂ and Al₂O₃ were in the form of monoclinic crystal andγ-Al₂O₃ crystal in the composite support, respectively. The characteristic peaks of monoclinic ZrO₂ andγ-Al₂O₃ were wide and sharp in the sample ZA-26. Whereas for sample ZA-17, the monoclinic ZrO₂ peak was not obvious, and for sample ZA-50, the peaks of both monoclinic ZrO₂ andγ-Al₂O₃ were not observed. ZrO₂ on the surface ofγ-Al₂O₃ was nanometer grain and uniformly dispersed. Compared to sample ZA-17 and ZA-26, the surface of ZA-50 contained more B-acid, whereas the surface of ZA-17 mainly had L-acid and almost no B acid. Compared to the CoMo supported on the single alumina or zirconia catalysts, the active component of the CoMo/ZrO₂-Al₂O₃ catalyst highly dispersed over the ZrO₂-Al₂O₃ mixed oxides and the amount of loaded CoMo close to the monolayer dispersion threshold, the surface of the CoMo/ZrO₂-Al₂O₃ catalyst had higher reduction behaviors and more active acid sites. The hydrodeoxygenation (HDO) reaction of phenol showed that the catalyst CoMo/ZA-50 had the highest conversion rate, the conversion was up to 84.7%, the product selectivity to benzene was 93.3%. The Phenol conversion rate which represented the catalytic activity followed the order: CoMo/ZA-50>CoMo/ZA-17>CoMo/ZA-26>CoMo/ZA-100>CoMo/ZA-00>CoMo/A1₂O₃ (P).The result of characterization showed that the catalysts prepared by the two methods were amorphous, molybdenum was in the form of oxides which was not reduced completely.The valence state of Mo in the catalyst which was prepared by ice bath method was +4 and +5,which different from the +5 and +6 of Mo in the catalyst prepared by ultrasonic technique, Mo⁴ is conducive to the generation of the ice bath method, The catalyst prepared by the ice bath method had a higher thermal Stability and exhibited excellent hydrodeoxygenation activity, the conversion of phenol was 79.3% at temperature 225℃which higher than the catalyst prepared by ultrasonic technique at the same reaction system(46.8%).</sup>