US 12,649,710 B2 · Process for the continuous production of either acrolein or acrylic acid as the target product from propene

Abstract

A process for the continuous production of either acrolein or acrylic acid as the target product from propene comprising a catalyzed gas phase partial oxidation of propene to yield a product gas containing the target product, transferring the target product in a separating zone from the product gas into the liquid phase and conducting out of the separating zone a stream of residual gas the major portion of which is returned into the partial oxidation and the remaining portion of said stream is purged from the process as off-gas from which synthesis gas can be produced or which can be added to synthesis gas produced otherwise.

A process for the continuous production of either acrolein or acrylic acid as the target product from propene comprising under stationary operating conditions

A) as an obligatory measure continuously passing in a first reaction stage a stream of a starting reaction gas mixture 1 consisting of
from 2 to 15% by volume of propene,
from 2.4 to 37.5% by volume of molecular oxygen,
from 0.5 to 20% by volume of water,
from 0 to 5% by volume of molecular nitrogen,
from 1 to 30% by volume of carbon monoxide,
from 1.5 to 65% by volume of carbon dioxide,
from 0 to 80% by volume of one or more than one hydrocarbon selected from the group consisting of methane, ethane, propane, n-butane, isobutane and ethene, and
from >0 to 5% by volume of other compounds including but not limited to acrolein and/or acrylic acid,
and containing
the molecular oxygen and the propene in a molar O2:propene ratio ranging from 1.2 to 2.5,
the carbon dioxide and the carbon monoxide in a molar CO2:CO ratio ranging from 1 to 4,
and the molecular oxygen and the molecular nitrogen in a molar O2:N2 ratio of at least 0.5,
at a reaction temperature of from 250° C. to 500° C. and a working pressure of from 1 bar to 6 bar through a first fixed catalyst bed comprising shaped catalyst bodies whose active mass is at least one multimetal oxide containing molybdenum (Mo), bismuth (Bi) and iron (Fe) in such a way, that the propene conversion on single pass is from 80 mol % to 99 mol % and the accompanying selectivity SA of the formation of the target product acrolein is from 70 mol % to 99 mol % to obtain a stream of the target product acrolein containing product gas mixture 1 leaving the first reaction stage,
and,
B) in case of acrylic acid being the target product,
optionally reducing the temperature of the product gas mixture leaving the first reaction stage by direct, indirect or direct and indirect cooling,
optionally adding secondary gas to said product gas mixture in the form of molecular oxygen, or inert gas, or molecular oxygen and inert gas, and
subsequently continuously passing in a second reaction stage a stream of the thus resulting starting reaction gas mixture 2 consisting of
from 2 to 15% by volume of acrolein,
from 1 to 45% by volume of molecular oxygen,
from 2 to 30% by volume of water,
from 0 to 5% by volume of molecular nitrogen,
from 1 to 30% by volume of carbon monoxide,
from 1.5 to 65% by volume of carbon dioxide,
from 0 to 80% by volume of one or more than one hydrocarbon selected
from the group consisting of methane, ethane, propane, n-butane, isobutane and ethene, and
from >0 to 5% by volume of other compounds including but not limited to propene and/or acrylic acid, and containing
the molecular oxygen and the acrolein in a molar O2:acrolein ratio ranging from 0.5 to 3,
the carbon dioxide and the carbon monoxide in a molar CO2:CO ratio ranging from 1 to 4, and
the molecular oxygen and the molecular nitrogen in a molar O2:N2 ratio of at least 0.25,
at a reaction temperature of from 200° C. to 450° C. and a working pressure of from 1 bar to 6 bar through a second fixed catalyst bed comprising shaped catalyst bodies whose active mass is at least one multimetal oxide containing molybdenum (Mo) and vanadium (V) in such a way, that the acrolein conversion on single pass is from 95 mol % to 99.99 mol % and the accompanying selectivity SAA of the formation of the target product acrylic acid assessed over both reaction stages and based on converted propene is from 80 mol % to 99.9 mol % to obtain a stream of the target product acrylic acid containing product gas mixture 2 leaving the second reaction stage,
and
C) either continuously transporting the stream of the target product acrolein containing product gas mixture 1 or the stream of the target product acrylic acid containing product gas mixture 2 into a separating zone and separating in the separating zone the respective target product from the respective product gas mixture through transferring at least 95 mol % of the respective target product contained in the respective product gas mixture from the gaseous phase into the liquid phase and continuously conducting out of the separating zone a total mass flow M of a residual gas mixture R which contains, of the total molar amount of those compounds contained in the product gas mixture continuously transported into the separating zone, which have as pure compounds at a working pressure of 1 bar a boiling point below 250 K, at least 95 mol %
and
D) recycling as gaseous stream P having the same composition as the residual gas mixture R a partial stream of the total mass flow M of residual gas mixture R continuously conducted out of the separating zone into the first reaction stage 1 as feed stream for preparing the stream of the starting reaction gas mixture 1 which shall contain the gaseous stream P, and discharging of the production process as off-gas stream O, having the same composition as the residual gas mixture R, the difference between the total mass flow M of residual gas mixture R continuously conducted out of the separating zone and the mass flow of recycle gaseous stream P, wherein
a) the mass flow of the recycle gaseous stream P is at least 85% but not more than 99.5% of the total mass flow M of residual gas mixture R continuously conducted out of the separating zone,
b) the mass flow of the off-gas stream O is not more than 15% but at least 0.5% of the total mass flow M of residual gas mixture R continuously conducted out of the separating zone, and
c) the composition C of the residual gas mixture R is
from 0.01 to 1% by volume of propene,
from 1 to 10% by volume of molecular oxygen,
from 0.5 to 25% by volume of water,
from 0 to 20% by volume of molecular nitrogen,
from 0.5 to 40% by volume of carbon monoxide,
from 1 to 75% by volume of carbon dioxide,
from 0 to 92% by volume of one or more than one hydrocarbon selected
from the group consisting of methane, ethane, propane, n-butane, isobutane and ethene, and
from 0.01 to 5% by volume of other compounds including but not limited to acrolein and/or acrylic acid,
wherein the starting reaction gas mixture 1 is formed from feed streams comprising oxygen of a purity of at least 90% by volume of O2 and no more than 10% by volume of N2;
and
wherein the off-gas stream oxygen is directly suitable for use as synthesis gas or as an additive to synthesis gas in a downstream chemical process, without prior removal of molecular nitrogen.

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Process for the continuous production of either acrolein or acrylic acid as the target product from propene

Life of this patent

Process for the continuous production of either acrolein or acrylic acid as the target product from propene

Life of this patent

Abstract

Claims18