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Acido-basic and catalytic properties of transition-metal containing Mg–Al hydrotalcites and their corresponding mixed oxides
Abstract Acido-basic MMgAlO mixed oxide catalysts (M=Mn, Fe, Co, Ni, Cu and Zn) were obtained by thermal decomposition of the corresponding layered double hydroxide (LDH) precursors. They were characterized by XRD, EDX, nitrogen adsorption, TG-DTG, NH3-TPD and CO2-TPD experiments. The cyanoethylation of methanol was used as a model reaction to evaluate the basicity of the LDHs and the corresponding mixed oxides. Mixed oxides were much more active than their LDH precursors, while both were quite selective for β-metoxypropionitrile. A straight correlation between the number of basic sites of the mixed oxides determined by CO2-TPD and their catalytic activity was evidenced. However, the equilibrium between the acid and basic sites is a key factor determining the catalytic activity.
Highlights ► Transition-metal containing LDHs as catalysts and catalyst precursors. ► Catalysts for cyanoethylation of methanol as a model of base catalyzed reaction. ► Mixed oxides much more active than their LDH precursors. ► Correlation between the number of basic sites of the mixed oxides and their activity. ► Key role played by the equilibrium between the acid and basic sites.
Acido-basic and catalytic properties of transition-metal containing Mg–Al hydrotalcites and their corresponding mixed oxides
Abstract Acido-basic MMgAlO mixed oxide catalysts (M=Mn, Fe, Co, Ni, Cu and Zn) were obtained by thermal decomposition of the corresponding layered double hydroxide (LDH) precursors. They were characterized by XRD, EDX, nitrogen adsorption, TG-DTG, NH3-TPD and CO2-TPD experiments. The cyanoethylation of methanol was used as a model reaction to evaluate the basicity of the LDHs and the corresponding mixed oxides. Mixed oxides were much more active than their LDH precursors, while both were quite selective for β-metoxypropionitrile. A straight correlation between the number of basic sites of the mixed oxides determined by CO2-TPD and their catalytic activity was evidenced. However, the equilibrium between the acid and basic sites is a key factor determining the catalytic activity.
Highlights ► Transition-metal containing LDHs as catalysts and catalyst precursors. ► Catalysts for cyanoethylation of methanol as a model of base catalyzed reaction. ► Mixed oxides much more active than their LDH precursors. ► Correlation between the number of basic sites of the mixed oxides and their activity. ► Key role played by the equilibrium between the acid and basic sites.
Acido-basic and catalytic properties of transition-metal containing Mg–Al hydrotalcites and their corresponding mixed oxides
Pavel, Octavian Dumitru (author) / Tichit, Didier (author) / Marcu, Ioan-Cezar (author)
Applied Clay Science ; 61 ; 52-58
2012-03-30
7 pages
Article (Journal)
Electronic Resource
English
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