METHOD TO PRODUCE ACROLEIN OR ACRYLIC ACID OR THEIR MIXTURE FROM PROPANE Russian patent published in 2012 - IPC C07C27/14 C07C45/35 C07C47/22 C07C51/25 C07C57/05 

FIELD: blasting.

SUBSTANCE: in the first reaction zone A at least two gaseous supply flows are supplied, containing propane, at least one of which contains fresh propane, to produce a reaction gas A; - in the reaction zone A the reaction gas A passes through at least one layer of catalyst, in which, by means of partial heterogeneous-catalysed dehydration of propane, molecular hydrogen and propylene are produced; - molecular oxygen is supplied into the reaction zone A, which oxidises in the reaction zone A at least a part of molecular hydrogen contained in the reaction gas A to water vapour - the gas-product A is taken from the reaction zone A, containing propylene, propane, molecular hydrogen and water vapour; B) water vapour contained in the gas-product A, if necessary, fully or partially by means of direct and/or indirect cooling, is separated in the first zone of separation I by the method of condensation with preservation of the gas-product A*; C) in the reaction zone B, by supply of molecular oxygen, the gas-product A or the gas-product A* is used to supply at least into one oxidisation reactor with the reaction gas B, comprising propane, propylene and molecular hydrogen, and propylene contained in it is exposed to heterogeneous-catalysed partial oxidation in the gas phase to produce acrolein or acrylic acid or their mixture as a target product, and also the gas-product B containing non-converted propane; D) from the reaction zone B the gas-product B is released, and the target product contained in it is separated in the second separation zone II, besides, the residual gas containing propane remains; E) whenever necessary, a part of the residual gas is returned having the composition of the residual gas, as a supply flow containing propane, into the reaction zone A; F) in the zone of separation III propane contained in the residual gas that has not been returned into the reaction zone A, from which earlier, if required, water vapour contained in it has been removed, possibly, by condensation and/or using a separating membrane, molecular hydrogen contained in it has been fully or partially removed, is separated by means of absorption in an organic dissolvent (absorbent) with production of absorbate containing propane; and G) in the separation zone IV propane is separated from absorbate and returned into the reaction zone A in the form of a supply flow containing propane, besides, in the reaction zone A enough amount of molecular hydrogen is oxidised to water vapour so that this hydrogen amount oxidised in the reaction zone A to the water vapour makes from 30 to 70 mol% of molecular hydrogen amount produced in the reaction zone A, and for values of the working pressure P in each case identified at the inlet to an appropriate area, in different zones of the method under the invention the following ratios are in effect: P_{reaction zone A}>P_{separation zone I}>P_{reaction zone B}>P_{separation zone II}>P_{separation zone III}>P_{separation zone IV}>P_{reaction zone A.}

EFFECT: higher yield.

27 cl, 6 ex