PROCESS FOR HYDROGENATION OF C13 ALDEHYDES IN AT LEAST TWO HYDROGENATION STAGES

Abstract

The present invention relates to a process for producing alcohols by hydrogenation of C13 aldehydes. The process according to the invention is performed in two consecutive hydrogenation stages, wherein the first hydrogenation stage employs an activated metal catalyst based on a nickel metal foam and the second stage employs a supported catalyst containing a catalytically active component from the group consisting of nickel, copper, chromium and mixtures thereof.

Claims

1. Process for producing alcohols by continuous hydrogenation of C13 aldehydes in at least two hydrogenation stages, wherein a stream containing the C13 aldehydes to be hydrogenated is hydrogenated with a hydrogen-containing gas over an activated metal catalyst based on a nickel metal foam in the liquid phase in the first hydrogenation stage comprising at least one recirculating reactor, wherein a crude product stream containing at least alcohols and unconverted aldehydes, of which a first portion is recycled and a second portion is passed to the second hydrogenation stage, is withdrawn from the at least one recirculating reactor, the second portion of the crude product stream is hydrogenated with a hydrogen-containing gas over a supported catalyst comprising a catalytically active component and a support material in the liquid phase in the second hydrogenation stage comprising at least one reactor operated in straight pass, wherein the catalytically active component is selected from the group consisting of nickel, copper, chromium and mixtures thereof and wherein the support material consists to an extent of more than 90% by weight of an oxidic material selected from the group consisting of aluminum oxide, aluminum silicate, silicon dioxide, titanium dioxide, zirconium oxide and mixtures of two or more thereof.

2. Process according to claim 1, wherein the stream employed in the process is an isotridecanal stream.

3. Process according to claim 1, wherein the activated metal catalyst based on a nickel metal foam is free from organic constituents, i.e. the sum of the weight fractions of carbon and carbon-containing compounds is less than 0.2% by weight of the total weight of the catalyst.

4. Process according to claim 1, wherein the activated metal catalyst based on a nickel metal foam contains 80% to 95% by weight of nickel and 5% to 15% by weight of aluminum in each case based on the total weight of the catalyst.

5. Process according to claim 4, wherein the activated metal catalyst based on a nickel metal foam additionally contains 0.01% to 3% by weight of molybdenum, particularly preferably 0.2% to 1.5% by weight of molybdenum and very particularly preferably 0.3% to 0.7% by weight of molybdenum, in each case based on the total weight of the catalyst.

6. Process according to claim 1, wherein the hydrogenation in the first hydrogenation stage is performed at a pressure of 5 to 150 bar, preferably 15 to 50 bar, particularly preferably 20 to 45 bar.

7. Process according to claim 1, wherein the hydrogenation in the first hydrogenation stage is performed at a temperature of 50° C. to 250° C., preferably 80° C. to 200° C., particularly preferably of 100° C. to 190° C.

8. Process according to claim 1, wherein the conversion of the hydrogenation in the first hydrogenation stage is at least 85%, preferably at least 90%, particularly preferably at least 95%.

9. Process according to claim 1, wherein the volume fraction of the activated metal catalyst based on a nickel metal foam in the total catalyst volume of all hydrogenation stages is from 30% to 80%, preferably 35% to 60%.

10. Process according to claim 1, wherein the support material of the supported catalyst is aluminum oxide, aluminum silicate or silicon dioxide.

11. Process according to claim 10, wherein the support material has a BET surface area of 70 to 350 m.sup.2/g, preferably 150 to 280 m.sup.2/g.

12. Process according to claim 1, wherein the hydrogenation in the second hydrogenation stage is performed at a pressure of 5 to 250 bar, preferably 10 to 150 bar, particularly preferably 15 to 30 bar.

13. Process according to claim 1, wherein the hydrogenation in the second hydrogenation stage is performed at a temperature of 100° C. to 220° C., preferably 120° C. to 210° C., particularly preferably 140° C. to 200° C.

14. Process according to claim 1, wherein the hydrogenation is carried out with a stoichiometric excess of hydrogen based on the aldehydes to be hydrogenated in both hydrogenation stages.

15. Process according to claim 1, wherein no aqueous phase is added in the first hydrogenation stage but an aqueous phase is added in the second hydrogenation stage.

Description

EXAMPLE 1 (INVENTIVE)

[0036] The hydrogenation was carried out in a hydrogenation stage with an activated metal catalyst based on a nickel metal foam (catalyst 1). The hydrogenation was performed with isotridecanal as the aldehyde.

Production of the Activated Metal Catalyst Based on a Nickel Metal Foam (Catalyst 1)

[0037] A nickel foam commercially available in rolls and having a thickness of 1.9 mm, a width of 300 mm and an average pore size of 580 μm was sprayed with a commercially available polyethyleneimine adhesion promoter solution and coated with an aluminum powder (oxygen content: 0.5% by weight) containing 96.5% by weight of aluminum particles having a particle size<150 μm (d.sub.90=68 μm) and subjected to a multistage heat treatment in the absence of oxygen at a maximum of 725° C. The mass ratios of the employed nickel foam and aluminum powder were chosen such that the ratio of aluminum to the total mass of the supported alloy was 28±2%. After cooling the material was comminuted with a laser into cuboidal particles having edge lengths of 4×4×1.9 mm. The resulting pourable material was activated by a 60 minute treatment in a 10% by weight aqueous sodium hydroxide solution at 60° C. The catalyst was subsequently washed with DM water until a pH<10 was achieved.

Molybdenum Doping

[0038] 250 g of the freshly produced catalyst were treated with a 55.4% by weight ammonium heptamolybdate solution over several hours until the molybdenum present in the solution was completely deposited on the activated nickel foam catalyst. Monitoring of the molybdenum deposition was effected by detection of molybdenum in the supernatant solution with Merckoquant oder Quantofix test strips. Treatment was terminated when molybdenum was no longer detectable in the supernatant solution. The catalyst was then washed twice with DM water. The final catalyst contained more than 87% by weight of nickel, about 12% by weight of aluminum and less than 1% by weight of molybdenum.

Performing the Reaction

[0039] The hydrogenation of isotridecanal was carried out in a tubular reactor in recirculating operation. The recirculating tubular reactor has an internal diameter of 40 mm and a length of 250 mm. Liquid phase (isotridecanal and recycled hydrogenation product) and gas phase (hydrogen) were run through the tubular reactor in cocurrent in trickle bed mode. 50 mL of catalyst 1 were employed in the recirculating reactor as hydrogenation catalyst. The amount of isotridecanal employed in the hydrogenation was 830 g (about 1 L). The recirculating stream was 45 L/h. Hydrogen regulation (max. 2 L/min) was effected via a constant offgas mode with an offgas stream of 1 L/min. The experiments were in each case performed at a pressure of 25 bar in the recirculating tubular reactor. The reaction in the recirculating tubular reactor was performed at reaction temperatures of 130° C. and 150° C. The output from the hydrogenation unit was analyzed for isotridecanal conversion by gas chromatography. The conversions measured at particular times are reported in table 2.

TABLE-US-00001 TABLE 2 Conversion over time for example 1 Ni foam Time/ conversion/% conversion/% min (130° C.) (150° C.) 5 23.54 28.96 10 34.17 43.39 15 48.33 56.88 30 69.14 84.27 45 84.40 95.49

EXAMPLE 2 (NONINVENTIVE)

[0040] Example 2 was performed in very largely the same way as example 1. Example 2 differs from example 1 in that a supported catalyst comprising nickel and copper as the catalytically active component and aluminum oxide as the support material (catalyst 2) was employed in the recirculating reactor. The reaction in the recirculating reactor was performed at reaction temperatures of 150° C. and 180° C. The conversions measured at particular times are reported in table 3.

TABLE-US-00002 TABLE 3 Conversion over time for example 2 Specialyst © 103 Time/ Conversion/% Conversion/% Min (150° C.) (180° C.) 5 10.02 23.08 10 15.44 34.35 15 20.42 44.59 30 34.78 69.41 45 48.38 84.93

[0041] It is very clearly apparent that the use of an activated metal catalyst based on a nickel metal foam allows higher conversions to be achieved in a shorter time. In addition, the activated metal catalyst based on a nickel metal foam makes it possible to employ lower temperatures in the reactor.

EXAMPLE 3

[0042] For a two-stage experimental setup the data were simulated. The necessary kinetic parameters were generated from the experimental data of examples 1 and 2. It was specified for the simulation that the hydrogenation of isotridecanal is to be performed in a tubular reactor in recirculating mode with a connected second tubular reactor in straight pass. The recirculating tubular reactor has an internal diameter of 20.5 mm and a length of 730 mm. The second reactor has an internal diameter of 20.5 mm and a length of 1000 mm. Liquid phase (isotridecanal and recycled hydrogenation product) and gas phase (hydrogen) are run through the tubular reactors in cocurrent in trickle bed mode. 100 mL of catalyst 1 are employed in the recirculating reactor as hydrogenation catalyst. 100 mL of catalyst 2 were used in the second reactor. The feed rate of isotridecanal employed in the hydrogenation is between 300 and 600 g/h. The recirculating stream is 25 L/h. The hydrogen (1.6 L/min-4 ml/min) regulation is effected via a constant offgas mode with an offgas stream of 1 L/min. The recirculating reactor is at a pressure of 26 bar and the second tubular reactor at a pressure of 22.5 bar. The reaction temperature in the recirculating tubular reactor is varied between 130° C. and 150° C. The temperature in the second tubular reactor is 180° C. The conversion of isotridecanal after the second reactor is >99%. The reaction conditions are reported in table 4. The corresponding conversions after the recirculating reactor are reported in table 5.

TABLE-US-00003 TABLE 4 Overview of hydrogenation conditions Recirculating reactor temperature/° C. 130-150 Recirculating reactor pressure/bar 26 Isotridecanal feed rate/g h.sup.−1 300-600 Liquid phase recirculation rate/L h.sup.−1 25 Volume of catalyst in recirculating reactor/mL (Katalysator 1) 100 Length of catalyst bed/mm 320 Offgas/NI min.sup.−1 1 WHSV/g isotridecanal*(ml catalyst * h).sup.−1 3-6

TABLE-US-00004 TABLE 5 Conversions after recirculating reactor under different hydrogenation conditions Temperature/° C. WHSV/g isotridecanal*(ml Katalysator * h).sup.−1 130 150 3 93.37% 97.31% 6 87.07% 94.59%

EXAMPLE 4 (NONINVENTIVE)

[0043] Example 4 was performed in very largely the same way as example 3. Example 4 differs from example 3 in that catalyst 2 was employed in each case in the first hydrogenation stage and in the second hydrogenation stage. The isotridecanal feed rate is also reduced to 270-530 g/h. Higher temperatures of 150-170° C. are also employed in the recirculating reactor. The conversion of isotridecanal after the second reactor is likewise >99%. An overview of the hydrogenation conditions is reported in table 6 which follows and the calculated conversions under the different reaction conditions are reported in table 7.

TABLE-US-00005 TABLE 6 Overview of hydrogenation conditions Recirculating reactor temperature/° C. 150-170 Recirculating reactor pressure/bar 26 Isotridecanal feed rate/g h.sup.−1 270-530 Liquid phase recirculation rate/L h.sup.−1 25 Volume of catalyst in recirculating reactor/mL (catalyst 2) 100 Length of catalyst bed/mm 640 Offgas/NI min.sup.−1 1 WHSV/g isotridecanal*(ml catalyst * h).sup.−1 2.7-5.3

TABLE-US-00006 TABLE 7 Conversions after recirculating reactor under different hydrogenation conditions Temperature/° C. WHSV/g isotridecanal*(ml catalyst * h).sup.−1 150 170 2.7 93.30% 96.31% 5.3 86.99% 92.83%

[0044] It is very clearly apparent that the use of an activated metal catalyst based on a nickel metal foam allows significantly higher feed rates to be established at unchanged conversions of >99% in the first hydrogenation stage. In addition, the activated metal catalyst based on a nickel metal foam makes it possible to employ lower temperatures in the recirculating reactor.

[0045] The preceding examples can be repeated with similar success by substituting the generically or specifically described reactants and/or operating conditions of this invention for those used in the preceding examples.

[0046] From the foregoing description, one skilled in the art can easily ascertain the essential characteristics of this invention and, without departing from the spirit and scope thereof, can make various changes and modifications of the invention to adapt it to various usages and conditions.