| 摘要 |
<p>A process for the production of ketones comprises contacting an aldehyde of the formula <FORM:1049990/C2/1> wherein each of the R1 and R2 groups is C1- 10 alkyl, and R3 is H or C1- 10 alkyl, in the vapour phase with water in a molar ratio of at least 5 mols. of water to one mol. of aldehyde, in the presence of a catalyst, which is either phosphoric acid supported on a solid carrier or is a solid acidic, silica-containing catalyst composite, at a temperature between 200-600 DEG C. The reaction is a re-arrangement represented by the equation <FORM:1049990/C2/2> The phosphoric acid catalyst is made suitably by soaking an inert support, e.g. ceramic Berl saddles or pellets of diatomaceous earth, pumice or silica gel, in an aqueous solution of the acid. The silica-type catalysts comprise an acidic metal oxide and the remainder is essentially silica. Suitable acidic metal oxides are alumina, zirconia, titania, magnesia and boria. The catalyst may be used in a fixed or fluidized bed. The reaction is preferably conducted between 375-500 DEG C. with a contact time of between 0.1 and 10.0 seconds. The mole ratio of water : aldehyde is preferably 10-21 : 1, but may be as high as 40 : 1. Superatmospheric pressure may be used. The Figure (not shown), shows a suitable apparatus for performing the reaction. The catalyst may be regenerated in conventional manner by contact with an oxygen-containing gas and an inert diluent, e.g. steam, at a sufficient temperature to burn off the carbonaceous deposits. The products are collected by, e.g. condensation or vapour-phase solvent-extraction, followed by condensation and distillation</p> |
