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Journal of Thermal Analysis and Calorimetry
Authors: L. Chmielarz, M. Zbroja, P. Kuśtrowski, B. Dudek, A. Rafalska-Łasocha, and R. Dziembaj

Abstract  

Alumina, zirconia and titania pillared montmorillonites additionally modified with silver were tested as catalysts of NO reduction with NH3 or C2H4. Ammonia was much more effective reducer of NO than ethylene. The silver containing TiO2-pillared clay has been found to be the most active catalyst for NO reduction both with NH3 or C2H4. Oxidation of the reducing agents by oxygen limited the NO conversion in the high temperature region. The ammonia and nitric oxide adsorption sites were studied by the temperature programmed desorption methods (TPD).

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Abstract

In the present work, protonated titanate nanoribbons were prepared by hydrothermal treating of TiO2 in alkali solution, followed by a thorough acid washing. The protonated titanate nanoribbons were employed as novel support for MnOx species and MnOx/protonated titanate was studied as a promising catalyst for the low temperature NH3-SCR reaction. The maximal NO conversion of ca. 98% was achieved over MnOx/protonated titanate at 200 °C under high GHSV of 50000 h−1. The existence of both MnO2 and Mn2O3 as active Mn species on protonated titanate was confirmed by XPS analysis, which was responsible for the high deNOx activity of MnOx/protonated titanate in NH3-SCR reaction.

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Abstract

Layered double hydroxides (LDHs) and their thermally derived mixed oxides have reached growing attention in past decades due to their wide application as catalysts or catalyst supports in organic/pharmaceutical synthesis, clean energy and environmental pollution control (decomposition of volatile organic compounds, photodecomposition, DeNox and DeSOx). Desired properties of LDHs can easily be tailored using different synthesis methods and introducing different bivalent and trivalent constituting metals. In this study, Mg–Al and Mg–Al–Fe LDHs were synthesized by low supersaturation (LS) and high supersaturation (HS) coprecipitation methods. The content of trivalent ions was varied in a wide range between 0.15 < x < 0.7 exceeding the optimal range for the single LDH phase synthesis (0.20 < x < 0.33). The intention was to induce the formation of different LDHs and consequently obtain, after thermal treatment, different multiphase mixed oxides. The properties of the precipitates were investigated by structural (XRD), chemical (AAS and EDS) and thermal analysis (TG–DTA). The study revealed that the LS method allows the formation of LDHs with an extended M(III) substitution (x = 0.5). Although, a more disordered structure in the stacking of layers was detected for HS samples, LS samples with the same initial composition showed lower thermal stability estimated by lower temperature of both LDH thermal decomposition transition stages. The thermal stability of LDHs was not influenced considerably with the introduction of a small amount of iron as ternary metal even though lower crystallinity of Mg–Al–Fe LDHs was observed.

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Journal of Thermal Analysis and Calorimetry
Authors: Lucjan Chmielarz, Małgorzata Rutkowska, Piotr Kuśtrowski, Marek Drozdek, Zofia Piwowarska, Barbara Dudek, Roman Dziembaj, and Marek Michalik

catalysts for various chemical processes was published. For example, Cu–Mg–Al mixed oxides were found to be active and selective catalysts for the DeNOx process [ 3 ] and selective catalytic oxidation of ammonia to nitrogen and water vapor [ 7

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