| 摘要 |
1. A process for preparing caprolactam by reacting 6-aminocapronitrile with water at a raised temperature, wherein the cyclization is conducted in liquid phase in the presence of a tetrahydroazepine derivative of the formula in the presence of a heterogeneous catalyst. 2. A process as claimed in Claim 1, wherein the heterogeneous catalyst contains no constituents that are soluble under the conditions of the reaction. 3. A process as claimed in Claim 1 or 2, wherein the reaction is carried out in a fixed bed reactor. 4. A process as claimed in any of Claims 1 to 3, wherein the reaction is carried out in the presence of a heterogeneous catalyst based on titanium dioxide, zirconium dioxide, cerium oxide or aluminum oxide. 5. A process as claimed in any of Claims 1 to 4, wherein the catalyst used comprises titanium dioxide having an anatase content within the range from 5 to 100% by weight and a rutile content within the range from 0 to 95% by weight, based on the total amount of titanium dioxide. 6. A process as claimed in any of Claims 1 to 5, wherein the starting mixture has a UV number (sum of all absorbencies of a 10% by weight solution in ethanol at wavelengths from 280 to 400 nm, based on a pathlength of 5 cm) within the range from 5 to 40,000. |
