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Fe-Containing Magnesium Aluminate Support for Stability and Carbon Control during Methane Reforming
ACS Catalysis ( IF 11.3 ) Pub Date : 2018-05-22 00:00:00 , DOI: 10.1021/acscatal.8b01039 Stavros Alexandros Theofanidis 1 , Vladimir V. Galvita 1 , Hilde Poelman 1 , N. V. R. Aditya Dharanipragada 1 , Alessandro Longo 2, 3 , Maria Meledina 4 , Gustaaf Van Tendeloo 4 , Christophe Detavernier 5 , Guy B. Marin 1
ACS Catalysis ( IF 11.3 ) Pub Date : 2018-05-22 00:00:00 , DOI: 10.1021/acscatal.8b01039 Stavros Alexandros Theofanidis 1 , Vladimir V. Galvita 1 , Hilde Poelman 1 , N. V. R. Aditya Dharanipragada 1 , Alessandro Longo 2, 3 , Maria Meledina 4 , Gustaaf Van Tendeloo 4 , Christophe Detavernier 5 , Guy B. Marin 1
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We report a MgFexAl2–xO4 synthetic spinel, where x varies from 0 to 0.26, as support for Ni-based catalysts, offering stability and carbon control under various conditions of methane reforming. By incorporation of Fe into a magnesium aluminate spinel, a support is created with redox functionality and high thermal stability, as concluded from temporal analysis of products (TAP) experiments and redox cycling, respectively. A diffusion coefficient of 3 × 10–17 m2 s–1 was estimated for lattice oxygen at 993 K from TAP experiments. X-ray diffraction (XRD) and extended X-ray absorption fine structure (EXAFS) modeling identified that the incorporation of iron occurs as Fe3+ in the octahedral sites of the spinel lattice, replacing aluminum. Simulation of the X-ray absorption near edge structure (XANES) spectrum of the reduced support showed that 60 ± 10% of iron was reduced from 3+ to 2+ at 1073 K, while there was no formation of metallic iron. A series of Ni/MgFexAl2–xO4 catalysts, where x varies from 0 to 0.26, was synthesized and reduced, yielding a supported Ni-Fe alloy. The evolution of the catalyst structure during H2 temperature-programmed reduction (TPR) and CO2 temperature-programmed oxidation (TPO) was examined using time-resolved in situ XRD and XANES. During reforming, iron in both the support and alloy keeps control of carbon accumulation, as confirmed by O2-TPO on the spent catalysts. By fine tuning the amount of Fe in MgFexAl2–xO4, a supported alloy was obtained with a Ni/Fe molar ratio of ∼10, which was active for reforming and stable. By comparison of the performance of Ni-based catalysts with Fe either incorporated into or deposited onto the support, the location of Fe within the support proved crucial for the stability and carbon mitigation under reforming conditions.
中文翻译：
甲烷重整过程中含铁的铝酸镁载体的稳定性和碳控制
我们报道了一种MgFe x Al 2– x O 4合成尖晶石，其中x在0到0.26之间变化，作为镍基催化剂的载体，在甲烷重整的各种条件下提供稳定性和碳控制。通过将Fe掺入铝酸镁尖晶石中，可以得到具有氧化还原功能和高热稳定性的载体，这分别由产品的时间分析（TAP）实验和氧化还原循环得出。扩散系数为3×10 –17 m 2 s –1通过TAP实验估算出在993 K时晶格氧的存在。X射线衍射（XRD）和扩展的X射线吸收精细结构（EXAFS）建模确定，铁的掺入以Fe 3+的形式出现在尖晶石晶格的八面体位置，代替了铝。还原载体的X射线吸收近边缘结构（XANES）光谱的模拟显示，在1073 K时，60±10％的铁从3+还原为2+，而没有形成金属铁。合成并还原了一系列Ni / MgFe x Al 2– x O 4催化剂，其中x在0到0.26之间变化，得到了负载型Ni-Fe合金。H 2期间催化剂结构的演变使用时间分辨原位XRD和XANES检查了程序升温还原（TPR）和CO 2程序升温氧化（TPO）。在重整过程中，载体和合金中的铁都可以控制碳的积累，这可通过废催化剂上的O 2 -TPO证实。通过微调MgFe x Al 2– x O 4中的Fe含量，可以得到Ni / Fe摩尔比约为10的负载合金，该合金具有良好的重整活性和稳定性。通过比较镍基催化剂与掺入或沉积在载体上的铁的性能，证明了铁在载体内的位置对于重整条件下的稳定性和减碳至关重要。
更新日期：2018-05-22
中文翻译：
甲烷重整过程中含铁的铝酸镁载体的稳定性和碳控制
我们报道了一种MgFe x Al 2– x O 4合成尖晶石，其中x在0到0.26之间变化，作为镍基催化剂的载体，在甲烷重整的各种条件下提供稳定性和碳控制。通过将Fe掺入铝酸镁尖晶石中，可以得到具有氧化还原功能和高热稳定性的载体，这分别由产品的时间分析（TAP）实验和氧化还原循环得出。扩散系数为3×10 –17 m 2 s –1通过TAP实验估算出在993 K时晶格氧的存在。X射线衍射（XRD）和扩展的X射线吸收精细结构（EXAFS）建模确定，铁的掺入以Fe 3+的形式出现在尖晶石晶格的八面体位置，代替了铝。还原载体的X射线吸收近边缘结构（XANES）光谱的模拟显示，在1073 K时，60±10％的铁从3+还原为2+，而没有形成金属铁。合成并还原了一系列Ni / MgFe x Al 2– x O 4催化剂，其中x在0到0.26之间变化，得到了负载型Ni-Fe合金。H 2期间催化剂结构的演变使用时间分辨原位XRD和XANES检查了程序升温还原（TPR）和CO 2程序升温氧化（TPO）。在重整过程中，载体和合金中的铁都可以控制碳的积累，这可通过废催化剂上的O 2 -TPO证实。通过微调MgFe x Al 2– x O 4中的Fe含量，可以得到Ni / Fe摩尔比约为10的负载合金，该合金具有良好的重整活性和稳定性。通过比较镍基催化剂与掺入或沉积在载体上的铁的性能，证明了铁在载体内的位置对于重整条件下的稳定性和减碳至关重要。
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