GB1443465A - Synthesis of aliphatic nitriles and apparatus for use therein - Google Patents

Abstract

1443465 Unsaturated nitriles by ammoxidation of olefins BF GOODRICH CO 25 Sept 1973 [25 Sept 1972] 44931/73 Heading C2C [Also in Division G1] Olefinically unsaturated aliphatic nitriles are produced by an ammoxidation process which comprises passing a mixture of an aliphatic alpha-monoolefin containing from 2 to 6 carbon atoms, ammonia and oxygen, or an oxygencontaining gas, through a solid ammoxidation catalyst at a temperature of 500-1150‹ F., wherein a portion of the gases leaving said catalyst is cooled, conditioned to and maintained at a temperature of 350-450‹ F., solids larger than 5 microns in diameter are removed from said gas, and the resulting filtered and temperature-conditioned gas sample is subjected to analysis. The gasse may be withdrawn continuously during the reaction near the exit from said catalyst, which is preferably an antimony/uranium oxide catalyst which may be regenerated at intervals by high temperature treatment, and the gases subsequently analysed by mass spectrographic analysis. The gases which have been removed from the reaction, after cooling, may be confined in a closed gas flow circuit maintained at 350-450‹ F. and the solids contained in the gas stream, and preferably all particles having a diameter of greater than 1 micron, may be removed by employing a series of filters of progressively smaller pore sizes. The quantity of the gases flowing in said closed gas circuit is relatively large compared to the quantity required for analysis, and the rate of flow therein is preferably sufficiently large to minimize lag in said analysis. The proportion of unreacted oxygen in the effluent gases is advantageously maintained, in response to said analysis, at a level sufficient to maintain a maximized state of oxidation in said catalyst. In the mass spectrographic analysis the composition of the effluent gases is determined from the amplitude of a peaked direct current electrical signal which is generated which is directly proportional to the proportion of each gaseous constituent; in response to the analysis the parameters of the process, such as the composition of the feed mixture, may be varied. The gases may be removed from the reaction by means of a shielded filter probe adapted to remove catalyst solids and, in addition to the closed gas circuit and mass spectrometer analyser, the overall circuit may comprise remote stream selector control modules, a direct reading oscillograph, a computer interface unit and computer and manual card punch data feed modules. The process may be utilized in a commercial nitrile plant employing two reactors. The production of acrylonitrile and methacrylonitrile is described and illustrated by means of flow diagrams.