BASF speeds up nitrous oxide process

Nitrous oxide may be better known as laughing gas, but it's no laughing matter. Toxic and suspected to contribute to both the greenhouse effect and ozone depletion, the gas is produced in production of the nylon intermediate adipic acid. BASF, along with other adipic acid producers, has agreed to cut nitrous oxide emissions `significantly' by the end of the decade - and the company now claims to have found a process to deliver a 90 per cent reduction within a year.

The process, part of a DM12million investment at BASF's Ludwigshafen headquarters complex, uses a catalyst to destroy the nitrous oxide. The catalyst, which was developed at the company's own research centre, is a blend of solid aluminium, zinc and copper oxides, and contains no noble metals. It is used in a fixed bed which, according to BASF, is designed to minimise the pressure-drop during the process.

BASF makes adipic acid by oxidising cyclohexane, then reacting the resulting cyclohexanone with nitric acid. In the new process, the gas stream from this reaction - which contains nitrous oxide - passes over the catalyst at a high temperature, and is decomposed into harmless nitrogen and oxygen.

According to the company, the process proved so successful in the laboratory that the normal pilot-plant stage of development was omitted to speed up the commercialisation of the application.

Construction work began on the plant - an end-of-pipe unit, which will be integrated into the existing Ludwigshafen adipic acid facility - in the second quarter of last year. Commissioning is expected to begin in early 1998. Once the unit is running, BASFintends to offer the process to third parties for licensing.