Process for preparing methacrolein

A process for preparing methacrolein comprising:

• (a) mixing water and an amine-acid catalyst to provide a catalyst stream;
• (b) sending the catalyst stream and a reaction stream comprising propionaldehyde, formaldehyde, and methanol to a reactor to produce a first intermediate stream comprising methacrolein, methanol, and at least 8 weight % water;
• (c) providing the first intermediate stream to a phase separator to produce (i) an organic phase comprising water and at least 70 weight % methacrolein, and (ii) an aqueous phase comprising methacrolein, methanol, amine-acid catalyst, and at least 70 weight % water;
• (d) distilling the organic phase in a first distillation column to produce (i) a second intermediate stream comprising methacrolein and less than 2 weight % water, and (ii) an overhead stream;
• (e) distilling the second intermediate stream in a second distillation column to produce (i) a first product stream comprising methacrolein and methanol in a combined amount of at least 97 weight %, less than 2 weight % water, and less than 1 weight % of impurities comprising one or more of acetic acid, propionic acid, methacrolein dimer, and 2-methyl-2-pentenal, and (ii) a waste stream;
• (f) recycling at least part of the overhead stream to the phase separator;
• (g) distilling the aqueous phase in a third distillation column to produce (i) a second product stream comprising methacrolein, methanol, and less than 5 weight % water, (ii) a bottoms stream comprising amine-acid catalyst, and (iii) a side draw stream comprising water and less than 2 weight % methanol;
• and
• (h) recycling at least part of the bottoms stream to the catalyst stream.