US EPA

7010457 

Journal Article 

Combustion synthesized crystalline La-Mn perovskite catalysts: Role of fuel molecule on thermal and chemical events 

Hammami, R; Batis, H; , 

2020 

Yes 

Arabian Journal of Chemistry
ISSN: 1878-5352 

ELSEVIER 

AMSTERDAM 

13 

1 

683-693 

10.1016/j.arabjc.2017.07.009 

WOS:000505076000054 

Solution combustion synthesis (SCS) technique was applied to produce LaMnO3+delta with the aim to investigate the effect of the chemical nature of a series of six fuel molecules (glycine, maleic acid, succinic acid, citric acid, acetic acid, urea) on the combustion reaction mechanism and physicochemical properties of the as-prepared powders. The whole SCS process was found to involve two types of combustion reactions depending on the used sacrificial molecules. Type I (with glycine, maleic acid and succinic acid) was characterized by a one-step exothermic reaction implying a semi-decomposed mixed nitrate-fuel complex and NO2 arising from manganese nitrate decomposition. The heat emission allows reaching the temperature suitable for well crystallized as-prepared perovskite powders. Type II (with citric acid, acetic acid and urea) was typified by a multi stage process in which intermediate decomposition reactions occurred before the formation of a mixed nitrate-fuel complex. In this case, the heat emission became lower than that expected from stoichiometric reaction, thus limiting the completion of the direct reaction for perovskite production. Consequently, part (with citric acid and acetic acid) or totally (with urea) of lanthanum and manganese remained distinctly combined in two amorphous phases (La(OH)(2)NO3, MnOx) that were intimately mixed. With respect to other fuels, combustion synthesis, using glycine, produced better crystallized, more defective and performant catalytic perovskite phase toward deep ethanol oxidation. (C) 2017 The Authors. Production and hosting by Elsevier B.V. on behalf of King Saud University. 

Combustion synthesis; Combustion mechanism; LaMnO3+delta; Fuel; Catalysis