Xiaodi Zhang,Jiming Wang,Guojie Zhang,Jun Liu,Ying Wang,Yuqing Zhao,Guoqiang Li
To improve the DRM reaction performance of the catalysts, a series of Co–Ni/WC-AC catalysts are prepared by impregnation using WC-AC as the support. The structural features of the fresh and spent catalysts are characterized by BET, XRD , H 2 -TPR, XPS and TG . The results show that the introduction of Ni in the 20Co/WC-AC catalyst promotes the conversion of W species to WC. Further, WC enhances the interaction between the active metal and the support. Thus, the activity and sintering resistance of Co–Ni/WC-AC catalysts are improved. It is also found that the introduction of different ratios of Ni has a significant effect on the chemical environment (oxygen environment) on the catalyst surface.10Co–10Ni/WC-AC catalysts showed high surface O α and O β contents of 26% and 53%, respectively. The catalyst shows excellent catalytic performance. The conversion of CH 4 and CO 2 is stable at about 84% and 85% at 800 °C.
Jun Liu,Yu Zhang,Zhoujie Liang,Guojie Zhang,Ying Wang,Yuqing Zhao,Guoqiang Li,Yongkang Lv
In this paper, a series of bimetallic catalysts with different Ni/Co ratios were prepared by co-impregnation method for application in methane dry reforming reaction. The effects of different Ni/Co ratios on the catalyst performance were investigated. The catalysts were characterized by XRD, BET, H 2 -TPR, TG, TEM and FTIR. The results showed that after the introduction of a certain amount of Co, the synergistic effect between Ni and Co enhanced the active component-carrier interaction, thus improving the dispersion of the active component of the catalyst, reducing the particle size of the metal, and increasing the activity of the catalyst. Meanwhile, the mechanistic study showed that the introduction of Co species with strong oxygen affinity facilitated the formation of oxygen vacancies. It makes the catalysts contain higher lattice oxygen and carbonate species, which was conducive to the elimination of carbon accumulation, thus improving the stability of catalysts. Therefore, the 10Ni-8Co-10Y/WC-AC catalyst exhibited excellent dry reforming of methane (DRM) performance at a Ni/Co ratio of 5:4. The conversions of CO 2 and CH 4 were 95 % and 88 % at 800 °C under atmospheric pressure, respectively.
Carbon materials are widely used as catalysts or supports due to their excellent properties. In this paper, the tungsten carbide-activated carbon (WC-AC) composite support was successfully prepared by in-situ carburizing on AC matrix, which is characterized by the covalent anchoring of WC on the AC support. The active metal Co was supported on WC-AC for dry reforming of methane (DRM). Samples were analyzed by N 2 physisorption measurements, XRD , XPS , H 2 -TPR, H 2 -TPD, CH 4 &CO 2 -TPSR, TG-DTG. The WC-AC stabilizes the disturbance of C in AC, alleviates the gasification effect of CO 2 and increases the active sites for CH 4 cracking. Moreover, WC provides a resistance-less bridge suitable for the Co 3+ → Co 2+ , resulting in a high Co 2+ /Co 3+ ratio on the catalyst surface . This enhances the interaction between the Co species and the WC-AC, thereby enhancing the CH 4 activation. In the process of WC-AC promoting Co 3+ →Co 2+ , the catalyst surface is accompanied by the generation of oxygen vacancies . This can enhance the dissociative adsorption of CO 2 on surface of the WC-cobalt oxide, and at the same time increase the relative proportion of adsorbed oxygen on the catalyst surface, thereby effectively inhibiting the formation of coke. However, the small amount of graphitic carbon generated due to the strong coupling of WC and Co is the main reason for deactivation of Co/WC-AC.
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