Ce/MgAl mixed oxides derived from hydrotalcite LDH precursors as highly efficient catalysts for ketonization of carboxylic acid

Abstract

Ketonization of carboxylic acids provides an attractive way for upgrading biomass feedstocks into biofuels.

Catalytic advancements in carboxylic acid ketonization and its perspectives on biomass valorisation

“…The "Mg3Al0.9Ce0.1" catalyst showed higher activity and stability for at least 7 hours on stream during propanoic acid ketonization at 350 °C, compared to the reference "Mg3Al" material. [110] Post-reaction XRD analysis showed that the structure of Mg3Al0.9Ce0.1 was maintained, while new diffraction peaks were observed for Mg3Al, possibly indicating lower structural stability. Finally, the impact of water on the stability of ketonization catalysts is complex and can be dependent on both the active material and reaction conditions.…”

“…For additional literature on the effect of metal oxide doping for ketonization, the reader is amongst others referred to the collection of listed references. [43,65,70,[108][109][110] Surface reduction via pre-treatment has been shown to be another strategy to improve the ketonization performance of metal oxide catalysts. Already in the 1970s, Jewur et al have presented the impact of hydrogen pre-treatment on iron oxide materials for the gas-phase ketonization of acetic acid at 360-440 °C.…”

Evaluation of the Catalytic Activity of Metal Phosphates and Related Oxides in the Ketonization of Propionic Acid

“…Following these two systematic screenings, an increasing number of authors and inventors focused their attention on catalytic materials consisting of amphoteric and/or reducible metal oxides such as TiO 2 [35], ZrO 2 [36][37][38][39], CeO 2 and MnO 2 [24], La 2 O 3 , and other rare-earth oxides [40]. Mixed metal oxides, such as Ce/Zr/O [41], Ce/Zr/Mn/O [42], Mn/Ce/O [24,43], Ce/Fe/O [44], Mn/Zn-chromite [45], and Mg/Al/Ce/O [46] and supported catalysts such as MnO 2 /Al 2 O 3 [37], TiO 2 /C [47] and Ru/TiO 2 [25] have been claimed to be active as well.…”

Catalytic Pyrolysis of Aliphatic Carboxylic Acids into Symmetric Ketones over Ceria-Based Catalysts: Kinetics, Isotope Effect and Mechanism

“…The ketonization reaction, or ketonic decarboxylation is one of the attractive ways to convert carboxylic acids into sustainable biofuels and valuable industrial products with high added value [15][16][17][18][19][20][21][22][23]. Ketonization provides for the formation of a new C-C bond in one step, preserves the initial functional group C = O, and significantly reduces the oxygen content in the molecule [15][16][17][18][19][20][21][22][23]. Ketonization provides for the formation of a new C-C C-C bond in one step, preserves the initial functional group C = O, and significantly reduces the oxygen content in the molecule due to decarboxylation and dehydration.…”

“…Despite the close attention to the ketonization reaction, last year's publications [15][16][17][18], including numerous studies and reviews [16,17,[19][20][21][22][23] suggested that the mechanism of this reaction is not completely clear. Over the past few decades, several basic mechanisms of this reaction have been proposed : (i) free-radical mechanism [24], (ii) direct concerted mechanism [20,25], (iii) mechanism involving an acyl intermediate [26], (iv) ketene based mechanisms [27][28][29], (v) and a betaketo-acid-intermediate based mechanisms [30][31][32][33][34][35] (Scheme 1).…”