| 摘要 |
Conjugated diolefines together with aldehydes and small amounts of mono-olefines are produced by contacting a 1,3-dioxane with a phosphate of a Group IIIB element as catalyst at elevated temperatures. 4,4-Dimethyl-1,3-dioxane produces isoprene and formaldehyde with small amounts of isobutene which with the formaldehyde may be used to produce more of the dioxane. Suitable conditions are 200-450 DEG C. and 0.1-100 liquid volumes of dioxane per volume of catalyst per hour, preferably mixed with steam, nitrogen or butane. The phosphate may be used alone or in amounts of 5-25% on a support such as silica which may contain combined sodium. Boron phosphate is preferred; the use of aluminium phosphate on silica and of mixed boron and aluminium phosphate is also exemplified.ALSO:A catalyst for the conversion of 1,3-dioxanes to conjugated diolefins comprises phosphates of a Group IIIB element supported, for example, on silica gel. The support preferably contains combined sodium and the catalyst may contain 5-25% by weight of boron and/or aluminium phosphate. |
