Cross-Aldol Condensation of Acetone and n-Butanol into Aliphatic Ketones over Supported Cu Catalysts on Ceria-Zirconia

Abstract

Abstract:A long-chain hydrocarbon biofuel of jet fuel range can be produced via aldol condensation of fermented products such as acetone and alcohols over the catalysts containing both metallic sites for the dehydrogenation of alcohols and basic sites for the condensation reaction. However, an efficient catalyst system has not been studied widely yet the route is promising for biofuel production. In this work, Cu catalysts supported on ceria-zirconia (Cu/xCeZr) were prepared using coprecipitated Ce x Zr 1-x O 2 supports with different Ce/Zr ratios for the cross-aldol condensation of acetone and n-butanol into mono-and di-alkylated aliphatic ketones, 2-heptanone and 6-undecanone. The acetone conversion and 6-undecanone selectivity increased with specific Cu surface area due to formation of the dehydrogenation product butyraldehyde at a higher concentration. The total yield of cross-aldol condensation products was strongly dependent on a combination of Cu sites and basic sites. This was confirmed by the results in the reaction between acetone and butyraldehyde over supported Cu catalysts that additionally examined the adsorbed acyl species on Cu surface taking part in the aldol condensation reaction. The best catalytic performance was achieved with Cu/0.8CeZr showing the largest Cu surface and the highest base site density among Cu/xCeZr catalysts. While the activity of Cu/0.8CeZ was comparable to or a little higher than that of Cu/MgO, the former catalyst was more stable than the latter suffering from the transformation of MgO to Mg(OH) 2 by the reaction. Consequently, it is suggested that Cu supported on ceria-zirconia of ceria rich contains such a dual function that it can efficiently catalyze the cross-aldol condensation of acetone and n-butanol.

Domino Reactions for Biofuel Production from Zymotic Biomass Wastes over Bifunctional Mg-Containing Catalysts

“…However, monoalkylated products with a carbon length of 5 to 7 dominated in the products, 6−10 and a higher selectivity for long-chain products (C 8 −C 15 ) with higher energy density was prone to be achieved over the homogeneous alkali-based catalyst. 11−14 Similar results have also been reported by Kim, 15 the selectivity for doublealkylated products is only 14% over Cu/CeZr. An increased selectivity for C 8 −C 15 hydrocarbons of nearly 60% was obtained using a physical mixture of Pd@C and CaO in Lee's work, 16 and the obtained mixture was further converted into the corresponding alkanes under the H 2 pressure of 3.5 MPa at 270 °C.…”

Ceria as an Efficient Nanocatalyst for Organic Transformations

“…Copyright 2017 Royal Society of Chemistry. condensation (Scheme 4) [160,161], Mannich reaction (Scheme 5) [162], Suzuki-Miyaura [163], Knoevenagel condensation (Scheme 6) [164] or Sonogashira cross couplings [165] have also been reported.…”

Promoting the Synthesis of Ethanol and Butanol by Salicylic Acid

“…Catalysts 2017, 7, 295 2 of 7 chemicals [17,18]. The effect of the diameter of MWCNTs and salicylic acid on the conversion of syngas and the selectivity of higher alcohols, especially ethanol and butanol, have been investigated.…”

“…The aim of this research is to investigate the effect of salicylic acid on the synthesis of higher alcohols from synthesis gas. The catalyst copper-cobalt/SA-MWCNTs have been used to catalyze the synthesis of higher alcohols, especially ethanol and butanol, from synthesis gas, as ethanol and butanol not only can be used as fuels but also can be used as feedstocks for producing chemicals [17,18]. The effect of the diameter of MWCNTs and salicylic acid on the conversion of syngas and the selectivity of higher alcohols, especially ethanol and butanol, have been investigated.…”