Patent GB-687775-A (GB)
Title: Process for the catalytic hydrogenation of aliphatic aldehydes in the gas phase
IPC: C07C45/41
Filed: 1950-03-01
Abstract: <PICT:0687775/IV (b)/1> <PICT:0687775/IV (b)/2> Aliphatic aldehydes, containing not more than 6 carbon atoms, are hydrogenated at elevated temperature in the gaseous phase and in the presence of a hydrogenation catalyst by passing a mixture comprising hydrogen and aldehyde vapour through a reaction chamber p  containing a close succession of catalyst zones and temperature regulating zones, the catalyst being arranged in a large number of parallel, narrow, vertical reaction spaces crossed by a large number of conduits for a circulating temperature-regulating medium.  The reaction is carried out at a temperature in the range 160-200 DEG  C.  It is preferable to use more than the theoretical amount of hydrogen and if it is intended to hydrogenate only the carbon double bond of an unsaturated aldehyde it is advisable to use a mixture of hydrogen and an inert gas, e.g. nitrogen. Preferably a mixture of 9 volumes of nitrogen to not more than 1 volume of hydrogen is used.  Usual hydrogenation catalysts, e.g. nickel or copper contact catalysts, which may be activated with other metals such as magnesium, may be used.  They may be used on carriers such as pumice or kieselguhr.  Suitable lower aliphatic aldehydes are acetaldehyde, propionaldehyde, n-butyraldehyde, pentanals, hexanals and the corresponding aldehydes with one double bond, e.g. crotonaldehyde.  In the Figures, the reaction chamber consists of a surrounding chamber 1 containing a large number of vertical parallel sheets 4 attached at two sides to the casing.  Above the sheets is a continuous space 5 permitting the gases entering at 2 to have access to all spaces 6 between the sheets.  Under the sheets is a horizontal perforated plate 7 through which the gases enter the space 8, finally leaving the chamber at 3. Through the entire length of the chamber and perpendicular to the sheets 4 extend numerous horizontal parallel conduits 9 through which passes the cooling medium, preferably water.  The adjacent horizontal rows of conduits are preferably in staggered relation to one another, as shown.  The catalyst is charged into the narrow vertical spaces between the sheets.  In the examples, apparatus of this type is used for the hydrogenation of (a) crotonaldehyde to butanol; (b) crotonaldehyde to butyraldehyde and (c) acetaldehyde to ethyl alcohol.  Specification 451,177, [Group III], and German Specifications 676,919, 708,889 and 720,685 are referred to.ALSO:Apparatus for the catalytic hydrogenation of aliphatic aldehydes, having not more than six carbon atoms, at elevated temperature in the gaseous phase consists of a reaction chamber containing a close succession of catalyst zones and temperature regulating zones, the catalyst being arranged in a large number of parallel, narrow, vertical reaction spaces crossed by a large number of conduits for a circulating temperature-regulating medium.  In the figures the reaction chamber consists of a surrounding case 1 containing a large number of vertical parallel sheets 4 attached at <PICT:0687775/III/1> <PICT:0687775/III/2> two sides to the casing. Above the sheets is a continuous space 5 permitting the gases entering at 2 to have access to all spaces 6 between the sheets. Under the sheets is a horizontal perforated plate 7 through which the gases enter the space 8, finally leaving the chamber at 3.  Through the entire length of the chamber and perpendicular to the sheets 4 extend numerous horizontal parallel conduits 9 through which passes the cooling medium, which is preferably water.  The adjacent horizontal rows of conduits are preferably in staggered relationship to each other.  The catalyst is charged into the narrow vertical spaces between the sheets. Specification 451,177, and German Specifications 676,919, 708,889 and 720,685 are referred to.