METHOD FOR PRODUCTION OF BUTADIENE AND HYDROGEN FROM ETHANOL IN ONE REACTION STEP WITH LOW WATER AND ENERGY CONSUMPTION Russian patent published in 2018 - IPC C07C1/20 C07C2/86 C07C11/167 

FIELD: chemistry.

SUBSTANCE: invention relates to a method for producing butadiene from ethanol feedstock containing at least 80 wt% ethanol. Method includes at least A) a step of converting ethanol to butadiene, comprising at least a reaction section, to which is fed at least an ethanol feedstock and part of the acetaldehyde stream from step E), operating at a pressure of 0.1 to 1.0 MPa and temperature from 300 to 400 °C in the presence of a catalyst, and a separation section, which enables to divide the stream exiting said reaction section into at least one gaseous stream and at least one liquid stream, wherein part of the acetaldehyde stream from step E), which is not fed into said reaction section, forms a purge stream; B) a step of extracting butadiene, comprising at least a compression section for compressing said gaseous stream exiting step A) to a pressure in the range of 0.1 to 1.0 MPa, a gas-liquid scrubbing section fed by an ethanol stream consisting of said ethanol feedstock, and/or part of the ethanol stream exiting step E), and is also fed by the compressed gaseous stream, wherein gases are fed at a temperature in the range from 10 to 60 °C, and liquids are fed at a temperature of 20 to -30 °C, and at least an ethanol stream enriched with butadiene, and a stream of gaseous by-products are obtained, and a distillation section, which is fed by said ethanol stream, enriched with butadiene, and a stream of crude butadiene and residue ethanol/acetaldehyde/water are obtained, wherein said distillation section operates at a pressure of 0.1 to 1 MPa; C) a step of washing with water of the gaseous by-products, which is fed by the stream of gaseous by-products from step B), as well as a part of the water-rich stream from said step E) and in which at least a stream of a water-alcohol mixture is obtained; D) a step of removing impurities and brown oils, fed by at least the ethanol/acetaldehyde/water stream exiting step B), and a part of the aqueous stream from step E) and at least a water/ethanol/acetaldehyde raffinate, a stream of light brown oils, and a stream of heavy brown oils are obtained; E) a wastewater treatment step which is fed by at least the water/ethanol/acetaldehyde raffinate exiting step D), and at least an ethanol stream, an acetaldehyde stream and a water stream are obtained; F) a step for first purification of butadiene, comprising at least a gas-liquid scrubbing section fed by the stream of crude butadiene from step B) from below, and, from the top, an aqueous stream which can be a water stream from a source external to the butadiene process, and/or part of the water stream exiting from step E), where in said purge section, a pre-purified stream of butadiene is obtained from above, and a stream of spent water is obtained from below; G) a step for further purification of butadiene fed by at least the pre-purified stream of butadiene exiting step F), and at least a purified stream of butadiene is obtained.

EFFECT: using the proposed method eliminates gaseous impurities, liquid impurities and brown oils, while at the same time minimising the loss of ethanol and acetaldehyde, thereby improving the overall performance of the installation while reducing the total water consumption required for the separation steps and obtaining very pure butadiene; significant reduction of total water consumption allows for lower energy consumption in the process and reduction of the size of the separation equipment.

15 cl, 4 ex, 6 dwg