| 摘要 |
Catalysts for use in the vapour phase conversion of chlorbenzenes to phenols comprise natural porous materials in which silica is contained in the free state or is formed when the material is treated with mineral acids, the said materials having been subjected before being used as catalysts to a treatment with a mineral acid liquid in order to free them sufficiently from constituents or admixtures detrimental to the catalytic action, especially iron. Suitable materials are kieselguhr, Bleaching earth, Florida earth, Fuller's earth, clays and asbestos, and after treatment with mineral acids they may be used in admixture with copper, cobalt, nickel, silver, gold, metals of the platinum group or compounds of any of these metals. In examples, a catalyst is prepared by freeing kieselguhr as far as possible from iron by boiling with hydrochloric acid and washing, or by successive treatment with a sulphide and sulphurous acid, and then saturating the material with a solution containing about 5 per cent of its weight of crystallized cupric chloride; it is then pressed into grains about the size of a pea; Bleaching earth, Florida earth, Fuller's earth, a clay or asbestos may be similarly treated, their activity as catalysts being increased by the addition of copper.ALSO:In the production of phenol or its homologues by treatment of chlorbenzene or its homologues in the vapour phase with steam at a raised temperature, instead of the catalysts employed in Specifications 354,948 and 358,903, there are used natural porous materials in which silica is contained in the free state or is formed when the material is treated with mineral acids, the said materials before being used as catalysts having been subjected to a treatment with a mineral acid liquid in order to free them sufficiently from constituents or admixtures detrimental to the catalytic action, especially iron. Suitable materials are kieselguhr, bleaching earth, Florida earth, fuller's earth, clays and asbestos, and after treatment with mineral acids they may be employed admixed with copper, cobalt, nickel, silver, gold, metals of the platinum group, or compounds of any of these metals. In examples: (1) kieselguhr is freed as far as possible from iron by boiling with hydrochloric acid and washing, or by successive treatment with a sulphide and sulphurous acid, and then saturated with a solution of cupric chloride and pressed into grains. A mixture of water vapour and chlorbenzene passed at 500 DEG C. over these grains gives a yield of about 97 per cent of phenol; ordinary kieselguhr which has not been freed from iron does not give a yield of more than 60 per cent under optimum conditions; (2) a natural silicate, such as bleaching earth, Florida earth, fuller's earth, a clay or asbestos is freed as far as possible from iron by one of the methods of (1) above, and a mixture of 2 parts of water vapour and 1 part of chlorbenzene vapour is passed at 500 DEG C. over such product; phenol is obtained in a yield of more than 95 per cent; the addition of copper increases the activity of the catalyst. |
