Investigation of Mn Promotion on HKUST‐1 Metal‐Organic Frameworks for Low‐Temperature Selective Catalytic Reduction of NO with NH₃

Abstract

A series of HKUST-1 supported catalysts (also known as Cu-BTC, or -benzene-1,3,5-tricarboxylate]) modified with different loadings of manganese were synthesized and characterized by powder X-ray diffraction, scanning electron microscopy/energy dispersive spectroscopy, nitrogen sorption, thermogravimetric analysis, and temperature-programmed desorption with NH 3 . The structural and textural properties of the solids, compared to the reference support, are preserved as much as possible when the manganese content is not higher than 5.0 wt.%. This allows to obtain effective catalysts at low temperatures (< 200°C) in the selective catalytic reduction of NO with NH 3 . The highest efficiency is obtained with the catalyst containing 3.75 wt.% of manganese which exhibits NO conversion of 68 % at weight hourly space velocity (WHSV) of 96,000 ml/h g. This performance in NO reduction is recognized to be one of the best in the series of HKUST-1-Mnx catalysts. Nevertheless, their narrow temperature window for the working reaction and sensitivity to the presence of water vapor and sulfur dioxide remain a drawback.

MOF-based catalysts: insights into the chemical transformation of greenhouse and toxic gases

“…Following this study, different loadings with Mn into HKUST-1 were tested. 129 It was investigated 2.5, 3.75, 5.0, 7.5, and 10.0 wt%, which HKUST-1-Mn(3.75) exhibits 68% conversion for NO x . The effect of Mn species was related to the localization within the framework since Mn clusters were mapped inside and outside the crystal, leading to facile access to the material.…”

“…The effect of Mn species was related to the localization within the framework since Mn clusters were mapped inside and outside the crystal, leading to facile access to the material. 129…”

Perspectives in Adsorptive and Catalytic Mitigations of NOx Using Metal–Organic Frameworks

“…The authors suggest that the combination of proper pore sizes, enhancement of redox activity via incorporation of Mn 4+ ions, and the synergistic effect between Mn 2+ and Cu 2+ results in superior DeNO x performance . The commercial HKUST-1 (Basolite C300) was examined under NH 3 -SCR conditions in the studies of Świrk et al , During the pretreatment step carried out in helium from 145 to 250 °C, the authors observed a gradually increasing formation of carbon dioxide with a heating ramp, highlighting the crucial role of the temperature. The temperature of 185 °C is recognized as the highest possible and carbon-free experimental adjustment, allowing the authors to prevent a partial decomposition of the organic framework.…”

“…After stabilizing the activity values, the NO and NH 3 conversions are reported to be 78% and 73%–84%, respectively. Different loadings of Mn (2.5, 3.75, 5.0, 7.5, and 10.0 wt %) were analyzed, and structural and textural modifications were evidenced by the creation of new mesopores . According to the authors, the mesoporosity could promote, to some extent, the diffusion properties, allowing easy access of molecules to enhance the catalytic activity in the NH 3 -SCR process.…”

“…According to the authors, the mesoporosity could promote, to some extent, the diffusion properties, allowing easy access of molecules to enhance the catalytic activity in the NH 3 -SCR process. Moreover, for the first time, Świrk et al , examined the commercial HKUST-1-supported catalysts in the presence of H 2 O (3.5 vol %) and SO 2 (100 ppm) in NH 3 -SCR. Both reactants were introduced separately.…”