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

Efficient Cross-Coupling of Acetone with Linear Aliphatic Alcohols over Supported Copper on a Fluorite-Type Pr2Zr2O7

In cross-coupling of biomass-derived acetone and alcohols contributing to the production of carbon-elongated chemicals and fuels, the essential catalyst components are metal dispersion for alcohol dehydrogenation and, more importantly, basicity for carbon–carbon coupling. Herein, we report the potential of co-precipitated praseodymia–zirconia solid solution (Pr2Zr2O7) as a support of Cu catalyst for the conversion of acetone and butanol into C7 and C11 products. Cu/Pr2Zr2O7 exhibits a high yield of C7 and C11 (ca. 84%) compared to Cu/ZrO2 and Cu/PrO1.83. Moreover, it is robust under the employed solvent-free conditions owing to a solid solution of Pr2Zr2O7 compared to PrO1.83 showing phase transition to PrOHCO3. It is also tolerant to up to 5 wt % water of the reactant mixture, recyclable once adequate post-treatment is employed after the reaction, and can convert the acetone–butanol–ethanol mixture into C5–C11 products at the nearly equivalent yield (82%) to the acetone–butanol mixture. Therefore, the Cu/Pr2Zr2O7 reported herein is an efficient catalyst for the coupling of acetone with linear aliphatic alcohols into biofuel precursors.

Low-Temperature Aldol Condensation of Aldehydes on R-TiO2(100)-(1 × 1): Exceptional Selectivity for α,β-Unsaturated Enal Production

Selective C-C coupling of oxygenates via aldol condensation has the potential to produce useful chemicals from aldehydes and ketones. Here we report a combined experimental and theoretical study on the aldol condensation of unbranched aldehydes (C_nH_2n+1-CHO, n = 1-4) on rutile (R)-TiO₂(100)-(1 × 1). Experimental results show that the R-TiO₂(100)-(1 × 1) surface has a very high reactivity and selectivity for aldol product formation from tested aldehydes at room temperature. Theoretical calculations indicate that the CH₃CHO enolization and the aldol dehydration occur with low energy barriers, and the 3-butanolal intermediate adsorbs on R-TiO₂(100)-(1 × 1) stably, suggesting that the surface has a "modest" acid-base strength for efficient crotonaldehyde formation. The adsorption configuration of CH₃CHO and surface structure of R-TiO₂(100)-(1 × 1) may contribute to the exclusive selectivity of (E)-crotonaldehyde formation, which provides us a deep insight into the high selectivity of aldol condensation of aldehydes on the TiO₂ catalyst.

Selective Coupling of Bioderived Aliphatic Alcohols with Acetone Using Hydrotalcite Derived Mg-Al Porous Metal Oxide and Raney Nickel

Fermentation of sugars to the so-called ABE mixture delivers a three component mixture of shorter chain oxygenates: acetone, n-butanol and ethanol. In order to convert these into liquid transportation fuels that are analogous to the currently used fossil energy carriers, novel catalytic chain elongation methods involving C-C bond formation are desired. Herein we report on a simple, non-noble-metal-based method for the highly selective coupling of 1-butanol and acetone into high molecular weight (C7-C11) ketones, as well as ABE mixtures into (C5-C11) ketones using the solid base Mg-Al-PMO in combination with small amount of Raney nickel. Upon hydrodeoxygenation, these ketones are converted to fuel range alkanes with excellent carbon utilization (up to 89%) using Earth abundant metal containing catalysis.

Promoting the Synthesis of Ethanol and Butanol by Salicylic Acid

Multiwalled carbon nanotubes (MWCNTs) were functionalized with salicylic acid (SA). The copper-cobalt catalyst was impregnated on the SA functionalized MWCNTs (SA-MWCNTs). The catalyst copper-cobalt/SA-MWCNTs was used to catalyze the synthesis of alcohols from synthesis gas. Salicylic acid can promote the synthesis of ethanol and butanol from synthesis gas, thus reducing the synthesis of methanol. This work demonstrated that salicylic acid not only can be used to functionalize carbon nanotubes, but also can enhance the production of ethanol and butanol from synthesis gas. On the other hand, the copper-cobalt catalyst supported on MWCNTs of 30 nm in diameter can synthesize more ethanol and butanol than supported on MWCNTs of 15 and 50 nm in diameter, indicating that the diameter of MWCNTs also has an effect on the synthesis of alcohols.