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Thermal stability of copper-based MOF under different atmospheres
Journal of Thermal Analysis and Calorimetry ( IF 3.0 ) Pub Date : 2022-12-05 , DOI: 10.1007/s10973-022-11769-8
Samara da Silva Montani , Juliana Fonseca de Lima , Fatima Maria Zanon Zotin , Luz Amparo Palacio

MIL-53(Cu), belonging to the group of metal–organic frameworks (MOFs) with terephthalate as a ligand, was prepared. The success of the synthesis was confirmed by XRD, FTIR, SEM and chemical analysis. The MOF thermal behavior was studied by thermogravimetry, in situ and ex situ XRD and mass spectrometry, using different atmospheres (inert, oxidizing and reducing). This MOF had a higher stability when the inert atmosphere was used (622 K), and this was lower (559 K) under an oxidizing atmosphere. The integrated intensities of the main peak of each phase in the X-ray diffractograms showed that under inert or reducing atmospheres (CO or H2) the decomposition generated metallic copper. Under oxidizing atmosphere, a mixture of copper oxides (Cu2O and CuO) was obtained, in which Cu2O was an intermediate, with only traces observed at 773 K. The FWHM calculation at the main peak of each phase indicated the formation of larger crystallites under hydrogen atmosphere and smaller ones under CO. There was a tendency of the formed copper oxides to sinter in the presence of air. The main volatile compounds formed during the thermal treatment of the MOF (decomposition of terephthalate) were CO2 and benzene. Thus, this study contributes to the development of new copper-based catalysts by the thermal treatment of MOF, which allows greater control of the phases formed (metallic Cu or CuO).



中文翻译:

铜基MOF在不同气氛下的热稳定性

制备了 MIL-53(Cu),属于以对苯二甲酸酯为配体的金属有机骨架 (MOF) 组。XRD、FTIR、SEM和化学分析证实了合成的成功。使用不同的气氛(惰性、氧化和还原),通过热重分析、原位和非原位 XRD 以及质谱法研究了 MOF 的热行为。这种 MOF 在使用惰性气氛 (622 K) 时具有更高的稳定性,而在氧化气氛下则较低 (559 K)。X射线衍射图中各相主峰的积分强度表明,在惰性或还原气氛(CO或H 2)下,分解生成金属铜。在氧化气氛下,得到铜氧化物(Cu 2 O和CuO)的混合物,其中Cu2 O 是中间体,在 773 K 时仅观察到痕量。各相主峰的 FWHM 计算表明在氢气氛下形成较大的微晶,在 CO 气氛下形成较小的微晶。形成的氧化铜有烧结的趋势在有空气的情况下。MOF热处理(对苯二甲酸分解)过程中形成的主要挥发性化合物是CO 2和苯。因此,本研究有助于通过 MOF 的热处理开发新型铜基催化剂,从而更好地控制所形成的相(金属 Cu 或 CuO)。

更新日期:2022-12-06
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