Ce0.5Zr0.5O2修饰的Ni/SiC、Fe/SiC和Co/SiC催化燃烧甲烷性能

以铈锆固溶体(Ce0.5Zr0.5O2)修饰的高比表面积SiC为载体,采用两步浸渍法制备了Ni、Fe和Co基催化剂,研究了其在煤层气催化燃烧脱氧中的催化活性和稳定性.利用X射线衍射(XRD)、X射线光电子能谱(XPS)、电感耦合等离子体质谱(ICP-MS)、高分辨透射电子显微镜(HRTEM)、比表面积(BET)、热重分析(TGA)和H2程序升温还原(H2-TPR)对催化剂进行了表征.分析结果表明,Ni、Fe和Co部分进入Ce0.5Zr0.5O2固溶体晶格内部,导致催化剂体相形成更多的缺陷;同时Ce0.5Zr0.5O2固溶体有助于加速金属氧化物和金属之间氧化还原过程的进行,促进了氧吸附、传输和对甲烷的活化.另外,SiC和Ce0.5Zr0.5O2固熔体良好的抗积碳性能,有效避免了催化剂在富甲烷反应气氛中因积碳而失活,从而使三种催化剂均具有优良的催化燃烧脱氧活性和稳定性.其中,Co/Ce0.5Zr0.5O2/SiC活性最高,可在320℃活化催化甲烷,并在410℃实现完全脱氧.

Methane Catalytic Combustion over Ni/SiC,Fe/SiC and Co/SiC Modified by Zr0.5Ce0.5O2 Solid Solution

We used Zr_0.5Ce_0.5O₂ solid solution modified high specific surface area SiC as the catalyst support and synthesized Ni/Ce_0.5Zr_0.5O₂/SiC, Fe/Ce_0.5Zr_0.5O₂/SiC, and Co/Ce_0.5Zr_0.5O₂/SiC catalysts by a two-step impregnation method. The catalytic activity and stability were investigated in the catalytic combustion deoxidation of coal-bed gas. The as-prepared catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), inductively coupled plasma- mass spectroscopy (ICP- MS), high- resolution transmission electron microscope (HRTEM), Brunner-Emmet-Teller (BET) measurements, thermal gravimetric analysis (TGA), and temperature-programmed reduction of H₂ (H₂-TPR). The results suggest that partial diffusion of Ni, Fe, and Co to the Ce_0.5Zr_0.5O₂ lattice leads to the formation of defects in the catalyst bulk phase. Ce_0.5Zr_0.5O₂ increased the redox process between metals and their oxides, improving the oxygen storage, mobility capacity, and the activation of CH₄. In addition, the excellent resistance of both SiC and Ce_0.5Zr_0.5O₂ solid solution to carbon deposition effectively inhibited coke formation on the catalysts during the combustion of rich methane atmosphere. Hence, these catalysts have good catalytic combustion deoxidation activity and stability. Co/ Ce_0.5Zr_0.5O₂/SiC catalyst had the best activity among the three catalysts: CH₄ was activated at 320 ℃ and O2 was completely removed at 410 ℃.