Zong-Pin Fu,Qi-Jie Zhou,Yun-Peng Zhao,Yu-Fa Wu,Fang-Jing Liu,Mei Zhong,Jian Li,Jing Liang,Jing-Pei Cao
The high oxygen content and low calorific value of bio-oil make it unsuitable for direct production of high energy density fuels. To address this issue, the C-O-C, C-O-H, and C-C bonds in the oxygenated compounds of bio-oil can be modified through hydrodeoxygenation (HDO) reaction. In this study, we synthesized a series of efficient Ni-CoOx/Hβ-u catalysts by impregnating Hβ molecular sieve modified with urea under mild conditions. The catalytic HDO performance of these catalysts was evaluated using guaiacol and dealkalized lignin oil as substrates. The results indicate that the Ni-15CoOx/Hβ-u catalyst demonstrated superior activity. The suitable specific surface area and pore volume of the Ni-15CoOx/Hβ-u catalysts, as well as uniformly dispersed metal particles on their surface, increased the number of active sites available for HDO. Additionally, the presence of defective sites on the CoOx surface and acidic sites on the catalyst facilitate the breaking of intermediate C-O bonds (deoxygenation) and dehydration reactions. Utilizing the Ni-15CoOx/Hβ-u catalysts, guaiacol was completely converted to cyclohexane with 100% selectivity (at 180 °C, 1.0 MPa H 2 , 40 min). Furthermore, the phenolic compounds in bio-oil could also be transformed into cycloalkanes via the HDO process. These findings suggest that the Ni-15CoOx/Hβ-u catalyst has the potential to effectively hydrodeoxygenate bio-oil under mild reaction conditions.
Currently, traditional hydrodeoxygenation (HDO) catalysts have various shortcomings such as low activity levels and vulnerability to deactivation. Therefore, a series of MXene-supported Ni-M (M = Pd, Pt, Ru) bimetallic catalysts were designed and prepared. The above catalysts were also comprehensively characterized using XRD, BET, H 2 -TPR, NH 3 -TPD, XPS, SEM and TEM methods. Moreover, due to the largest particular specific surface area, moderate amount of acid sites and the strongest three-electron transfer channels between support and active metals of Ni-Pd/MXene catalyst, it exhibited the superior catalytic performance to achieve 100 % guaiacol conversion and 35.15 % highest overall yields of HDO products (Y HDO ) under the optimal reaction conditions (at 340 °C for 8 h, utilizing in-situ hydrogen source: formic acid). Furthermore, a detailed discussion on the main reaction pathways and mechanism of guaiacol HDO catalyzed by Ni-Pd/MXene was provided, an unique bimetallic synergistic “relay catalytic” theory has been proposed. Kinetic studies revealed that phenol, one of the main HDO products, is primarily generated via guaiacol demethoxylation, while catechol dehydroxylation to phenol acts as the rate-determining step. This work introduces a new strategy for the development of HDO catalysts.
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