Synthesis of 3-hydroxybutyraldehyde over highly stable solid base catalysts prepared from layered double hydroxides: Fid-Bau Portal

Synthesis of 3-hydroxybutyraldehyde over highly stable solid base catalysts prepared from layered double hydroxides

Jiang, Yuanyuan / Liu, Haolan / Zhao, Huaiyuan / Zhou, Ruru / Du, Weichen / Wang, Songlin / Hou, Zhaoyin

Abstract 3-Hydroxybutyraldehyde (3-HBA) is an important intermediate for the manufacture of biodegradable plastics (polyhydroxyalkanoate), and it is of great significance to find an efficient way for the catalytic synthesis of 3-HBA from surplus acetaldehyde. In this work, a series of MgxAlO(x+1.5)-t (t referred to the calcination temperature) solid bases were prepared via the controlled calcination of MgxAl layered double hydroxides with different ratio of Mg/Al and tested in the aldol condensation of acetaldehyde to 3-HBA. Characterization results revealed that the formed MgO particles were embedded in magnesium aluminate spinel (MgAl2O4) in Mg3AlO4.5–1100, which exhibited excellent activity and stability in the continuous liquid flow condensation of acetaldehyde. The detected selectivity of 3-HBA reached 89.0% with a 73.8% conversion of acetaldehyde at 25 °C and WHSV⁻¹ = 2.8 h. Meantime, Mg3AlO4.5–1100 catalyst could retain its activity within 300 h on stream. What's more, the reaction mechanism over Mg3AlO4.5–1100 catalyst was proposed according to the results of several experiments.

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Highlights • Highly stable solid base (Mg3AlO4.5–1100) was prepared via the calcination of layered double hydroxides. • Mg3AlO4.5–1100 exhibited excellent activity in the aldol condensation of acetaldehyde to 3-HBA. • The productivity on Mg3AlO4.5–1100 reached 279.6 mg-3-HBA/g-cat/h at 25 °C and WHSV⁻¹ = 0.6 h. • Mg3AlO4.5–1100 kept its reactivity within 300 h on stream in continuous flow reaction.