Mg bulk and surface modification on Ni/Y2Ti2O7 catalyst for dry reforming of methane

• Published in: International journal of hydrogen energy 2024-11, Vol.92, p.1121-1132
• Main Authors: Mao, Lei, Le, Zhiping, Ma, Jiamei, Liu, Teng, Huang, Wenwen, Xu, Junwei, Xu, Xianglan, Wang, Xiang, Liu, Yuxi, Fang, Xiuzhong
• Format: Article
• Language: English
• Subjects: Coke-resistance; Dry reforming of methane; Mg modification; MgNiOx solid solution; Ni/Y2Ti2O7 catalyst
• ISSN: 0360-3199
• DOI: 10.1016/j.ijhydene.2024.10.345

Dry reforming of methane (DRM) can simultaneously convert two greenhouse gases, CH4 and CO2, into high value-added synthetic gas, which can effectively alleviate the energy crisis and optimize the human ecological environment. In this work, the effect of Mg addition method on the activity of the Y2Ti2O7 pyrochlore supported Ni catalysts was investigated in DRM. The H2-TPR and XPS results showed that Mg modification enhanced the interaction between Ni and Y2Ti2O7 pyrochlore support. Thus, much smaller Ni grains with better thermal stability could be achieved on the Mg doped Ni/Y2Ti2O7 catalyst, as evidenced by the XRD, H2-TPD and TEM results. CO2-assistant CH4-TPSR demonstrated that Mg surface modification can facilitate the reaction between the activated CO2∗ and the H∗ produced by CH4 dissociation. Mg incorporation increased the basic site of the Ni/Y2Ti2O7 catalyst, as evidenced by CO2-TPD-MS results, which was conducive to the adsorption and activation of CO2 to promote the removal of coke deposition. Consequently, Ni/Y1·5Mg0·5Ti2O7 and Ni–MgO/Y2Ti2O7 catalysts exhibit higher stability and more potent coke resistance than the unmodified Ni/Y2Ti2O7 sample. It is concluded that higher Ni0 dispersion and more mobile active oxygen species are the main reasons for the improvement of activity and coke resistance of the Ni/Y2Ti2O7 catalysts. In addition, in situ DRIFTS results confirmed that CO2 activation of all catalysts followed the formate intermediate species path. [Display omitted] •More alkaline sites and mobile oxygen species could be obtained by Mg doping.•Mg doping enhanced the stronger interaction between Ni sites and Y2Ti2O7 support.•Mg doping accelerated the reaction between activated CO2∗ and dissociated H∗.•Ni–MgO/Y2Ti2O7 exhibited good activity-stability and potent coke-resistance.•CO2 activation on these catalysts followed the formate intermediate species path.