Synthesis of 3-picoline from acrolein and ammonia through a liquid-phase reaction pathway using SO42−/ZrO2-FeZSM-5 as catalyst

• Pre-dilution of acrolein favored the liquid-phase synthesis of 3-picoline.
• Solid acid catalyst was employed in the reaction.
• A 60% yield of 3-picoline was obtained over a SO42−/ZrO2-FeZSM-5 catalyst.
• Possible side reactions were studied.

The synthesis of 3-picoline from the liquid-phase condensation of acrolein and ammonium acetate under atmospheric pressure was conducted by first dissolving ammonium acetate in a C2C6 carboxyl acid medium in the presence of solid acid catalyst, and then, feeding gradually a solution of acrolein in a C2C6 carboxyl acid solvent. It was found that the employment of acetic acid, among various carboxyl acids tested, as both the reaction medium and solvent of acrolein, was most favorable, due to the obvious promotion to the formation of 3-picolind in liquid phase and retarding to the side reaction of acrolein polymerization in gas phase. The SO42−/ZrO2-FeZSM-5 catalyst possesses the largest acid acidity and thus exhibited the largest yield of 3-picoline, among various solid acid catalysts. By employing the SO42−/ZrO2-FeZSM-5 catalyst and acetic acid as both the reaction medium and solvent of acrolein, the influencing factors, including reaction temperature, molar ratio of ammonium acetate/acrolein/acetic acid, concentration and feeding rate of acrolein solution as well as usage of catalyst, were systematically investigated. The results indicated that an as high as 60% yield of 3-picoline could be achieved from a batch with molar ratio composition acrolein/ammonium acetate/acetic acid = 0.025/0.125/1.8, under the conditions of reaction temperature = 130 °C, concentration of acrolein solution = 14 wt%, feeding speed of acrolein solution = 12 mL/h and catalyst usage = 0.7 g/g (acrolein).

3-Picoline was generated, involving propylene as intermediate, from the reaction of acrolein and ammonium acetate over a SO42−/ZrO2-FeZSM-5 solid super-acid catalyst, while the polymerization of acrolein or/and propylene imine was retarded by using acetic acid as both the solvent of acrolein and reaction medium.Figure optionsDownload as PowerPoint slide