| 主权项 |
1. A process for the manufacture of acrylonitrile comprising:
a) introducing in a first dehydration reactor, glycerol in the form of an aqueous solution, and molecular oxygen; a) dehydrating glycerol in the gas phase to acrolein in the presence of a first acid catalyst at a temperature ranging from 150° C. to 500° C., and a pressure between 1 and 5 bar, forming a gas stream comprising acrolein, water, unconverted glycerol and by-products; b) sending the said gas stream to a condensation unit which separates, on the one hand, a mixture rich in water that contains the heavy by-products, and, on the other hand, a stream rich in acrolein that contains the light by-products and optionally inert gases; c) recycling a portion of the separated stream rich in water in order to dilute the glycerol to the desired concentration and using the condensation unit to reheat the aqueous glycerol solution; d) sending the separated stream rich in acrolein to an ammoxidation reactor comprising a fixed bed of an ammoxidation catalyst for the acrolein which is not saturated with ammonia at the reaction temperature; e) carrying out the ammoxidation reaction in the presence of molecular oxygen at a content ranging from 3 to 20 vol %, relative to the incoming stream, and in the presence of a gas mixture comprising inert gases and ammonia, the ammonia/acrolein molar ratio being between 1 and 1.5, at a temperature between 400° C. and 500° C., and under a pressure between 1 and 5 bar, forming an effluent rich in acrylonitrile; f) purifying said effluent in a separation unit in order to separate, on the one hand, the light products and the unconverted acrolein, and on the other hand, acrylonitrile; g) recycling partly the gases obtained at the top of the separation unit of the step f), in the ammoxidation reactor at the step e). |
