| 摘要 |
A catalyst for the dehydration of phenyl methyl carbinol consists of titania, preferably of a high grade of purity, which may be supported on sandstone, silica, fused alumina, and the like. Thus, it may first be activated with sulphuric acid, and applied dry in an amount of 10-15 per cent. by weight, to ceramically-bonded fused alumina wetted with water, and the product dried at 150 DEG C. Alternatively, pure titania is made into a paste with water, dried at 130-150 DEG C. powdered, and pelleted, for example to 3/16 -/ba3/8 inch size, and fired at 800 DEG C. or above, preferably 1000 DEG C. The pellets may then be activated with nitric, hydrochloric, phosphoric or sulphuric acid, washed, and dried. The Specification as open to inspection under Sect. 91 comprises also the use of potassium bisulphate as the catalyst, supported as above described. This subject-matter does not appear in the Specification as accepted.ALSO:Styrene is prepared by vapour phase dehydration of phenyl methyl carbinol using titania as catalyst. Temperature is 180-280 DEG , preferably 220-250 DEG C. At 180-220 DEG C. steam or reduced pressure may be used to assist vaporization. The titania, preferably of a high grade of purity, may be supported on sandstone, silica, fused alumina and the like. Thus, it may first be activated with sulphuric acid, and applied dry, in an amount of 10-15 per cent by weight, to ceramically-bonded fused alumina wetted with water, and the product dried at 150 DEG C. Alternatively, pure titania is made into a paste with water, dried at 130-150 DEG C., powdered and pelleted, for example to 3/16 -/ba3/8 inch size, and fired at 800 DEG C. or above, preferably 1000 DEG C. The pellets may then be activated with nitric, hydrochloric, phosphoric or sulphuric acid, washed and dried. Crude phenyl methyl carbinol obtained by hydrogenating acetophenone and containing the latter may be treated. In examples, supported or pelleted titania catalysts prepared as above are used. The Specification as open to inspection under Sect. 91 comprises also the use of potassium bisulphate as the catalyst, preferably at 215-230 DEG C. and supported as above described. This subject-matter does not appear in the Specification as accepted. |
