C4+; Air

methyl methacrylate

A process for the manufacture of methyl methacrylate (MMA) from isobutylene or tertiary butanol, air, and methanol.

Description: Methacrylic acid (MAA) is produced directly from isobutylene or tertiary butanol in high yield by the vapor phase catalytic oxidation in two stages, which is carried out in the reactors of multi-tubular and fixed-catalyst-bed type. Product gas from the first-stage reactor is direactly introduced into the second-stage reactor without isolating methacrolein.

   MAA is scrubbed with water to obtain an aqueous solution of MAA and then unreacted methacrolein in the product gas is recovered and recycle to the second stage. Effluent gas from the oxidation section is catalytically incinerated and a part of the offgas is reused as a diluent for the reactor feed gas. MAA is extracted from the aqueous solution with an organic solvent.

   After separation of a part of the solvent, MAA is continuously esterified in liquid phase in the presence of a catalyst. High-purity MMA is obtained by extraction and distillation.

Economics: This process offers a more competitive route to MMA than the conventional acetone cyanohydrin process. The catalysts are very stable and their lifetime is more than two years.

B/L capital investment: 5,500 million yen for 40,000 t/y MMA plant (as of October 1984, on Japan base)

Raw materials and utilities consumption (per 1kg of MMA):

Isobutylene, 100% (kg)
Methanol (kg)
Catalyst and auxiliary chemicals (yen)     
Steam (kg), (credit)
Electric power (kWh)
Cooling water (kg)

0.86
0.34
18
-1.0
0.50
0.30

Component Names and Formula