Deactivation Mechanism, Countermeasures, and Enhanced CH4 Oxidation Performance of Nickel/Cobalt Oxides. Issue 8 (2nd September 2019)

• Record Type: Journal Article
• Authors: Chen, Junfei; Zou, Xuelin; Rui, Zebao; Ji, Hongbing
• Other Names: Li Yongdan guestEditor.; Veser Götz guestEditor.
• Is Part Of: Energy technology. Volume 8:Issue 8(2020:Aug.)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2019-09-02
• Subjects: catalytic combustion -- methane -- nickel cobaltite -- thermal stabilities; Energy development -- Periodicals; Power resources -- Periodicals; 333.79
• DOI: 10.1002/ente.201900641
• Languages: English
• ISSNs: 2194-4288

Abstract

Abstract : Nickel/cobalt oxides (Ni x Co3− x O4 ) are enticing candidates for replacing noble metal catalysts in low‐temperature methane complete oxidation. Poor thermal stability is the main drawback of these kinds of materials. Understanding the relationships among the morphology, composition, activity, and thermal stability of Ni x Co3− x O4 is crucial to develop robust Ni x Co3− x O4 for CH4 oxidation. Herein, a series of hierarchical Ni x Co3− x O4 ( x = 0.1, 0.5, or 1) are synthesized by a hydrothermal method followed by thermal treatment at various temperatures for lean methane combustion. The results show that the decrease in surface area, surface Ni 3+ + Co 3+ amount, and defective oxygen amount are the main reasons for the performance degradation of Ni x Co3− x O4 after an elevated temperature treatment (500 and 800 °C). Proper decrease in the Ni/Co ratio, that is, Ni0.5 Co2.5 O4, slows down the thermal deactivation of NiCo2 O4 . Hierarchically structured Ni0.5 Co2.5 O4 shows high CH4 oxidation activity with a 90% CH4 conversion temperature of 380 °C and a satisfied long‐term (>50 h) CH4 combustion stability even after thermal treatment at 500 °C. These results demonstrate that simultaneous consideration of morphology manipulation and Ni/Co ratio optimization is an effective strategy for designing robust nickel/cobalt oxides for catalytic methane combustion. Abstract : Understanding the relationships among morphology, Ni/Co ratio, activity, and thermal stability is critical to the design of robust Ni x Co3− x O4 for future CH4 oxidation applications. Herein, special attention is paid to the deactivation mechanism of Ni x Co3− x O4 catalysts in methane oxidation and the improvement of CH4 oxidation performance through synergism between morphology control and Ni/Co ratio optimization.