| 摘要 |
1,3-Cyclohexadiene is prepared by passing 1-cyclohexene-3-ol in the vapour phase through a catalyst obtained by heating agglomerates of transition alumina containing less than 1000 p.p.m. of alkali metals, expressed as Na2O, with a mixture of air and steam at 200 DEG to 450 DEG C., followed by a calcining step in dry air at 300 DEG to 600 DEG C. Dry air is defined as containing less than 100 p.p.m. by weight of water. The heating of the alumina agglomerates with the air-steam mixture takes at least 15 minutes, preferably 1 to 6 hours. The mixture of air and steam contains preferably 10 to 90% by weight of steam and the dehydration process preferably takes place at 180 DEG to 300 DEG C. The 1-cyclohexene-3-ol may be diluted with steam, the molar ratio of water: 1-cyclohexene-3-ol being 1:5 to 20:1 and the 1-cyclohexene-3-ol may also contain up to 5% by weight of cyclohexanol. The effluent from the reactor is condensed, the organic phase decanted and the 1,3-cyclohexadiene obtained by distillation.ALSO:Agglomerates of transition alumina containing less than 1000 p.p.m. of alkali metal, expressed as Na2O, are heated with a mixture of air and steam at 200 DEG to 450 DEG C. and then calcined in dry air (i.e. containing less than 100 p.p.m. water) at 300 DEG to 600 DEG C.ALSO:1, 3 cyclohexadine is prepared by passing 1-cyclohexene 3-ol in the vapour phase through a catalyst obtained by heating agglomerates of transition alumina containing less than 1000 ppm of alkali metals, expressed as Na2O, with a mixture of air and steam at 200 DEG to 450 DEG C., followed by a calcining step in dry air at 300 DEG to 600 DEG C. The catalysts may have a surface area of 340 sq.in./gm. |
