Ethanol Guerbet condensation is an environmentally friendly process for preparing biofuel such as n‐butanol and alcohols with more than 4 carbon atoms. In this work, a multifunctional catalyst Ni/TiO2 was prepared by an excess impregnation method and its catalytic performance for ethanol Guerbet condensation was evaluated. The selectivity of C4‐C8 alcohols reached up to almost 70% (41.4% of n‐butanol) at nearly half conversion of ethanol at 210 °C and 10 h. Based on GC‐MS analysis results, the products in ethanol Guerbet condensation were identified and a reaction network was established. The presence of acetaldehyde and 2‐crotonaldehyde in the reaction products verified that Ni/TiO2‐catalyzed ethanol condensation followed the traditional dehydrogenation‐condensation‐hydrogenation reaction mechanism.
n-Butanol Guerbet condensation is a green route to 2-ethylhexanol (2EHO). The by-product water not only hinders the progress of reaction and reduces the selectivity of 2EHO, but also causes catalyst...
The Guerbet condensation of bio-ethanol is a green route to the synthesis of n-butanol. However, this route suffers from its by-product water which not only affects adversely the condensation reaction performance, but also causes the deactivation of the catalyst. Hence, the water by-product should be removed. This goal is achieved by integrating the Guerbet condensation of ethanol with acetal hydrolysis in this work. First, the Guerbet condensation of ethanol and the integrated reaction of ethanol Guerbet condensation with acetal hydrolysis were thermodynamically analyzed. The results showed that acetal hydrolysis can promote the Guerbet condensation of ethanol. Then the performance of the two reaction systems was compared experimentally using Ni−Cu/TiO 2 catalyst. The selectivity of n-butanol reached 44.4% at an ethanol conversion of 47.9% in ethanol Guerbet condensation while the selectivity of n-butanol increased to 50.4% at an ethanol conversion of 50.2% in the integrated reaction with an ethanol/acetal molar ratio of 20. Finally, the two reaction systems were kinetically analyzed, and the results showed that acetal hydrolysis can lower the activation energy of the ethanol dehydrogenation step and acetaldehyde aldol self-condensation step, thus effectively promoting the Guerbet condensation of ethanol.
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