PEP Review 81-1-3
Caprolactam vis SNIA Viscosa Process
Published: December 1981
The SNIA Viscosa process for producing caprolactam from toluene consists of three main steps.
- Oxidation of toluene to benzoic acid
- Hydrogenation of benzoic acid to hexahydrobenzoic acid
- Nitrosation of hexahydrobenzoic acid to caprolactam.
The nitrosation yield has been increased to 95% compared to 86% in the earlier version of the process. The improvement was obtained by operating within a narrower temperature range and by close control of the nitrose concentration in each stage of the reactor.
As there are fewer by-products from this step, the purification of caprolactam is simpler. All chemical purification steps have been eliminated and only physical purification methods are required.
Overall, the effect of the improvements has resulted in about a 10% reduction in capital investment and about the same reduction in production costs. The product value, including 25% return on investment before taxes dropped by ~10% also.