Multistage aldehyde hydrogenation
AssigneeDavy McKee (London) Limited
InventorsMichael W. Bradley, Andrew G. Hiles, John W. Kippax
Life of this patent
Estimating the term…
Abstract
A multi-stage hydrogenation process for hydrogenating a vaporous aldehyde to a corresponding alcohol utilizing a plurality of adiabatic catalytic stages is described. Hydrogenation is allowed to occur substantially completely and adiabatically in each stage. Further vaporous aldehyde or a mixture of hydrogen and vaporous aldehyde is added to the essentially aldehyde-free mixture exiting each catalytic stage prior to entry to the next stage.
Claims37
A process for hydrogenating an aldehyde to a corresponding alcohol which comprises providing a plurality of adiabatically operated catalytic stages arranged one after another, including a first catalytic stage and one or more other catalytic stages including a final catalytic stage, each catalytic stage containing a charge of a hydrogenation catalyst effective for vapour phase catalytic hydrogenation of aldehydes, supplying to the first catalytic stage at a temperature at least as high as the threshold temperature for the hydrogenation reaction a first vaporous mixture comprising vaporous aldehyde and excess hydrogen, allowing catalytic hydrogenation to occur substantially adiabatically in the first catalytic stage so as to convert to corresponding alcohol substantially all aldehyde supplied to the first catalytic stage, supplying to the, or to each, other catalytic stage a vaporous mixture comprising (a) a substantially aldehyde free intermediate product mixture comprising unreacted hydrogen and corresponding alcohol recovered from the preceding catalytic stage and (b) supplementary vaporous material that is richer in aldehyde than the first vaporous mixture and is selected from vaporous aldehyde and mixtures of vaporous aldehyde with hydrogen at a hydrogen:aldehyde molar ratio less than that of the first vaporous mixture, the vaporous mixture supplied to the, or to each, other catalytic stage being in each case at a temperature at least as high as the threshold temperature for the hydrogenation reaction, allowing catalytic hydrogenation to occur substantially adiabatically in the, or in each, other catalytic stage, thereby to convert to corresponding alcohol substantially all aldehyde supplied to that stage, and recovering from the final catalytic stage a substantially aldehyde-free vaporous reaction mixture containing corresponding alcohol.
A process for vapour phase hydrogenation of an aldehyde to the corresponding alcohol which comprises providing a catalytic hydrogenation zone comprising n catalytic stages in series, where n is an integer of at least 2, each catalytic stage containing a charge of hydrogenation catalyst effective for vapour phase catalytic hydrogenation of aldehydes, supplying to the first catalytic stage a first vaporous mixture comprising excess hydrogen and the aldehyde at a first predetermined hydrogen-aldehyde molar ratio and at a first temperature which is equal to, or is in excess of, the threshold temperature for the hydrogenation catalyst thereof, allowing catalytic hydrogenation to occur substantially adiabatically in each catalytic stage, thereby to effect hydrogenation to corresponding alcohol of substantially all aldehyde supplied to that stage, supplying substantially aldehyde free vaporous product mixture from the, or from each, mth catalytic stage in the series, where m is an integer equal to or less than (n-1), to the corresponding (m+1)th catalytic stage in the series, supplying also to the, or to each, (m+1)th catalytic stage further vaporous material that is richer in aldehyde than the first vaporous mixture and is selected from vaporous aldehyde and mixtures of vaporous aldehyde and hydrogen having a hydrogen:aldehyde molar ratio that is less than the first predetermined ratio so as to form, together with the vaporous product mixture from the mth catalytic stage, a vaporous mixture having a predetermined hydrogen:aldehyde molar ratio which may be the same as, or may be different from, the first predetermined ratio or the corresponding molar ratio for the vaporous mixture supplied to any other stage, controlling the inlet temperature to the, or to each, (m+1)th catalytic stage to a predetermined temperature which is equal to, or is in excess of, the threshold temperature for the catalyst, and recovering from the nth catalytic stage a substantially aldehyde-free final vaporous product mixture containing the corresponding alcohol.
A process for hydrogenating an aldehyde to a corresponding alcohol which comprises providing a catalytic hydrogenation zone comprising first, second and third catalytic stages in series, each catalytic stage containing a charge of a hydrogenation catalyst effective for vapour phase catalytic hydrogenation of aldehydes, supplying to the first catalytic stage a first vaporous mixture comprising excess hydrogen and the aldehyde at a first predetermined molar ratio at a first inlet temperature which is equal to, or is in excess of, the threshold temperature for the hydrogenation catalyst, allowing catalytic hydrogenation to occur substantially completely and substantially adiabatically in the first catalytic stage, supplying substantially aldehyde free first product mixture comprising corresponding alcohol and unreacted hydrogen from the first catalytic stage to the second catalytic stage, supplying also to the second catalytic stage further vaporous material that is richer in aldehyde than the first vaporous mixture and is selected from vaporous aldehyde and mixtures of vaporous aldehyde and hydrogen having a hydrogen:aldehyde molar ratio which is less than the first predetermined molar ratio, so as to form, together with the first product mixture, a second vaporous mixture containing hydrogen and vaporous aldehyde and having a predetermined second hydrogen:aldehyde molar ratio which may be equal to, or may be different from, the first ratio, controlling the inlet temperature to the second catalytic stage to a predetermined temperature which is equal to, or is in excess of, the threshold temperature of the catalyst, allowing catalytic hydrogenation to occur substantially completely and substantially adiabatically in the second catalytic stage, supplying substantially aldehyde free second product mixture comprising corresponding alcohol and unreacted hydrogen from the second catalytic stage to the third catalytic stage, supplying also to the third catalytic stage further vaporous material that is richer in aldehyde than the first vaporous mixture and is selected from vaporous aldehyde and mixtures of vaporous aldehyde and hydrogen having a hydrogen:aldehyde molar ratio which is less than the first predetermined molar ratio so as to form together with the second product mixture, a third vaporous mixture containing hydrogen and vaporous aldehyde and having a predetermined third hydrogen:aldehyde molar ratio which may be equal to, or may be different from, the first and/or second ratios, controlling the inlet temperature to the third catalytic stage to a predetermined temperature equal to or in excess of the threshold temperature of the catalyst, allowing catalytic hydrogenation to occur substantially completely and substantially adiabatically in the third catalytic stage, and recovering from the third catalytic stage a substantially aldehyde free third product mixture containing the corresponding alcohol.
Dependencies are inferred from the claim text.