Process for Converting Butanol into Propylene

Abstract

Process for selective the conversion of primary C4 alcohol into propylene comprising: contacting a stream (1) containing essentially a primary C4 alcohol with at least one catalyst at a temperature ranging from 150 C. to 500 C. and at pressure ranging from 0.01 MPa to 10 MPa conditions effective to transform said primary C4 alcohol into an effluent stream (2, 5) containing essentially propylene, carbon monoxide and di-hydrogen, said transformation of primary C4 alcohol comprising at least a reaction of decarbonylation and optionally a decarboxylation reaction, said at least one catalyst comprising a support being a non-acidic i.e. having a TPD NH3 of less than 50 preferably less than 40 mol/g and optionally a non-basic catalyst i.e. having a TPD CO2 of less than 100 preferably less than 50 mol/g.

Claims

1.-15. (canceled)

16. A process for the conversion of primary C4 alcohol into propylene comprising: contacting a stream (1) containing a primary C4 alcohol with at least one catalyst at a temperature ranging from 150 C. to 500 C. and at pressure ranging from 0.01 MPa to 10 MPa to transform the primary C4 alcohol into an effluent stream (2, 5) containing propylene, carbon monoxide and di-hydrogen, the transformation of primary C4 alcohol comprising at least a reaction of decarbonylation and optionally a decarboxylation reaction, the at least one catalyst comprising support which is non-acidic, having a TPD NH3 of less than 50 mol/g and which is also a non-basic, having a TPD CO2 of less than 100 mol/g.

17. The process according to claim 16 wherein stream (1) is contacted with the at least one catalyst to produce an effluent stream (2, 5) wherein at least 1 wt % of primary C4 alcohol is converted into propylene, carbon monoxide and di-hydrogen.

18. The process according to claim 16, wherein the step of contacting the primary C4 alcohol stream (1) with the at least one catalyst is performed in a single reaction zone (A) and the at least one catalyst is submitted before the transformation of primary C4 alcohol to a reduction in presence of di-hydrogen (H.sub.2) at a temperature of at least 400 C. for at least 1 hour, at least one diluent being optionally added to stream (1), and optionally the diluent is recovered in the effluent stream (2) and optionally recycled in stream (1).

19. The process according to claim 16 wherein stream (1) is contacted with at least one first catalyst comprising a support which is non-acidic, having a TPD NH3 of less than 50 mol/g and which is also a non-basic, having a TPD CO2 of less than 100 mol/g in a first reaction zone (B) at a temperature ranging from 150 C. to 500 C. and at pressure ranging from 0.01 MPa to 10 MPa to produce a stream (3) in which at least 1 wt % of primary C4 alcohol is converted into butyraldehyde, at least one diluent being optionally added to the stream (1), optionally separating unconverted compounds from stream (3) and optionally the diluent if any and recycling unconverted compounds and optionally the diluent if any into stream (1) to obtain a purified stream (4), contacting stream (3) and/or optionally the purified stream (4) with at least one second catalyst comprising a support which is non-acidic, having a TPD NH3 of less than 50 mol/g and which is also a non-basic, having a TPD CO2 of less than 100 mol/g, in a second reaction zone (C) at a temperature ranging from 150 C. to 500 C. and at pressure ranging from 0.01 MPa to 10 MPa to produce an effluent stream (5) comprising propylene, carbon monoxide and di-hydrogen, the second non-acidic catalyst, being optionally reduced, before the transformation of stream (3) and/or stream (4), in presence of di-hydrogen at a temperature of at least 400 C. for at least 1 hour, optionally separating unconverted compounds and optionally the diluent if any from effluent stream (5) and recycling unconverted compounds into purified stream (4) and/or in stream (1), optionally recycling the diluent if any in stream (1) and/or stream (3).

20. The process according to claim 19, wherein the first catalyst and the second catalyst is the same catalyst comprising a non-acidic support having a TPD NH3 of less than 50 and a non-basic support having a TPD CO2 of less than 100 mol/g.

21. The process according to claim 19, wherein the stream (3) and/or optionally the purified stream (4) treated in the second reaction zone (C) present a content of unconverted compounds of less than 10 wt %.

22. The process according to claim 18, wherein the reaction zones (A), (B), (C) are each operated under a temperature ranging ranging from 200 C. to 450 C., and under pressure ranging from 0.1 MPa to 3.5 MPa.

23. The process according to claim 19, wherein reaction zone (B) is operated under a temperature ranging from 150 C. to 450 C., and under partial pressure of butanols ranging from 0.01 MPa to 2.5 MPa and wherein reaction zone (C) is operated at a temperature ranging from 150 C. to 500 C., and under partial pressure of butyraldehyde ranging from 0.01 MPa to 1 MPa.

24. The process according to claim 16, wherein the catalyst, is chosen from: a non-acidic and non-basic catalyst comprising a support which is non-acidic and non-basic, and optionally at least one metal dispersed on the at least one support at a content of at least 0.05 wt % based on the weight of the catalyst; a non-acidic and non-basic catalyst consisting of at least one support being metal in a metallic state, in an oxidized state or in a partially reduced oxide state or optionally the at least one metal is a transition metal chosen in the groups IB, IIB, IVB, VB, VIB, VIIIB, preferably at least one metal is chosen in the groups IIIA and IVA or chosen among palladium and/or platinum.

25. The process according to claim 24, wherein the non-acidic and non-basic catalyst comprises two metals chosen in the groups IB, IVB, VB, VIB, VIIIB, IIIA, IVA.

26. The process according to claim 24, wherein the at least one non-acidic and optionally non-basic support is selected from passivated alumina, activated carbon, metal silicate, perovskytes, silica-magnesia, phalocianides, silica, ceria, zirconia, titania, clays.

27. The process according to claim 16, wherein the at least one non-acidic and optionally non-basic catalyst contains one or several elements chosen from Na, K, P, B, S, each at a content of less than 2 wt % based on the weight of the catalyst.

28. The process according to claim 16 wherein secondary products formed via dehydration of the primary C4 alcohol are separated and cracked in lower olefins in a dedicated olefin cracking reaction zone or recycled back to stream (1).

29. The process according to claim 16 wherein the primary C4 alcohol is originated from a bio source optionally via a fermentation route or is originated from a mixture of heavy alcohols synthesis, which was produced via syn-gas routes.

30. The process according to claim 16 wherein the carbon monoxide and di-hydrogen are separated from stream (2, 5) and are subsequently used in at least one of the following processes: transformation to liquid products via fermentation route, production of alcohols from C1 to C5, such as methanol via syn-gas conversion routes, production of hydrocarbons via syn-gas conversion routes including Fischer-Tropsch synthesis, olefins synthesis, aromatics synthesis or any combination of thereof, hydro oligomerization of ethylene, selective transformation of the ethylene to propanal, acetone, (n-, i-) propanols and propylene.

Description

DESCRIPTION OF THE FIGURES

[0160] The FIG. 1 represents a simplified process scheme of the first embodiment of the present invention. A stream (1) comprising essentially primary butanol is sent to a reaction zone (A). In this reaction zone, primary butanol is decarbonylated in order to produce propylene, carbon monoxide and di-hydrogen. Unconverted primary butanol can optionally be separated and recycled back to stream (1) via stream (2) (dashed line). Optionally, the diluent present in stream (1) may also be separated at the exit of reaction zone (A) and recycled in stream (1) via stream (2).

[0161] The FIG. 2 represents a simplified process scheme of the second embodiment of the present invention. A stream (1) comprising essentially primary butanol is sent to a reaction zone (B) where it is at least partially converted via oxidation into the corresponding aldehyde. The stream (3) exiting the reaction zone (B) contains unconverted primary butanol, the corresponding aldehyde and maybe also the corresponding carboxylic acid in case the oxidation reaction was not completely selective. Optionally part or all of the unconverted primary butanol and/or the diluents can be separated and recycled into stream (1) via stream (3) (dashed line) to obtain a purified stream (4). The stream (4) is then sent to a reaction zone (C) where the decarbonylation and optionally the decarboxylation reaction are performed. At the exit of the reaction zone (C), the stream (5) containing mainly propylene, CO and H.sub.2 is obtained. This stream (5) can optionally be purified to separate propylene from the CO and H.sub.2 that can further be recycled into a butanol or methanol production unit (not presented on the figure). The stream (5) can optionally be purified to separated unconverted compounds and diluents and recycle them either at the inlet of reaction zone (C) through stream (5) (dashed line) or at the inlet of reaction zone (B) through stream (5) (dashed line).

[0162] The FIG. 3 represents the selectivity of the products formed as a function of the temperature in the iso-butyraldehyde formation from iso-butanol (example 12).

[0163] The FIG. 4 represents the selectivity of the products formed as a function of the temperature in the iso-butyraldehyde and propylene formation from iso-butanol (example 13).

[0164] The FIG. 5 represents the CO.sub.2 desorption curves of the samples normalized on the weight (see procedure for the CO.sub.2 uptake measurements).

PROCEDURE FOR BASICITY MEASUREMENT (TPD CO2 or CO.SUB.2 .Uptake)

[0165] The measurement of Temperature-programmed desorption of CO.sub.2 is performed in a Pyrex cell containing about 0.4 g of sample in form of the fraction 35-45 mesh. The cell is placed in an oven of the AUTOCHEM II 2920 equipped with TCD detector and the following steps are carried out:

[0166] Activation: this step is performed under a flow rate of dried (over molecular sieve e.g. 3 A or 4 A) He of 50 cm.sup.3/min (<0.001% of water). The temperature is increased from room temperature to 550 C. with a rate of 10 C./min. The temperature is then maintained at 550 C. during 1 h. The temperature is then decreased to 40 C. with a rate of 10 C./min.

[0167] Saturation: this step is performed at 40 C. During two hours, the solid is put in contact with a flow of 30 cm.sup.3/min of a dried (over molecular sieve e.g. 3 A or 4 A, <0.001% of water) pure CO.sub.2. Then, during the next 1 h, the solid is put in contact with a flow rate of 50 cm.sup.3//min of dried (over molecular sieve e.g. 3 A or 4 A, <0.001% of water) He to remove the physisorbed CO.sub.2.

[0168] Analysis: this step is performed under a flow of 50 cm.sup.3/min of dried (over molecular sieve e.g. 3 A or 4 A, <0.001% of water) He. The temperature is increased to 500 C. with a rate of 10 C./min. Once the temperature of 500 C. has been reached, it is maintained for 1 h. The cell is then cooled down and weighted. The amount of CO.sub.2 desorbed in the temperature range from 40 C. to 500 C. from the solid is referenced to the weight of the sample.

PROCEDURE FOR ACIDITY MEASUREMENT (TPD NH.SUB.3.)

[0169] The measurement of Temperature-programmed desorption of ammonia is performed in a Pyrex cell containing about 0.4 g of sample in form of the fraction 35-45 mesh. The cell is placed in an oven of the AUTOCHEM II 2920 equipped with TCD detector and the following steps are carried out:

[0170] Activation: this step is performed under a flow rate of dried (over molecular sieve e.g. 3 A or 4 A) He of 50 cm.sup.3/min (<0.001% of water). The temperature is increased from room temperature to 600 C. with a rate of 10 C./min. The temperature is then maintained at 600 C. during 1 h. The temperature is then decreased to 100 C. with a rate of 10 C./min.

[0171] Saturation: this step is performed at 100 C. During a first hour, the solid is put in contact with a flow of 30 cm.sup.3/min of a dried (over molecular sieve e.g. 3 A or 4 A, <0.001% of water) mixture of 10 weight % of NH.sub.3 diluted in He. Then, during the next 2 h, the solid is put in contact with a flow rate of 50 cm.sup.3 /min of dried (over molecular sieve e.g. 3 A or 4 A, <0.001% of water) He to remove the physisorbed NH.sub.3.

[0172] Analysis: this step is performed under a flow of 50 cm.sup.3/min of dried (over molecular sieve e.g. 3 A or 4 A, <0.001% of water) He. The temperature is increased to 600 C. with a rate of 10 C./min. Once the temperature of 600 C. has been reached, it is maintained for 1 hr. The cell is then cooled down and weighted. The amount of NH.sub.3 desorbed from the solid is referenced to the weight of the sample.

EXAMPLES

[0173] The iso-butanol conversion is the ratio (iso-butanol introduced in the reactoriso-butanol leaving the reactor)/(iso-butanol introduced in the reactor).

[0174] The iso-butanal conversion is the ratio (iso-butanal introduced in the reactoriso-butanol leaving the reactor)/(iso-butanol introduced in the reactor),

[0175] The propylene selectivity is the ratio, on carbon basis, (propylene leaving the reactor)/(iso-butanol or iso-butanal converted in the reactor).

[0176] The selectivity in C4 olefins is the ratio, on carbon basis, (C4 olefins leaving the reactor)/(iso-butanol or iso-butanol converted in the reactor).

[0177] The isobutanal selectivity is the ratio, on carbon basis, (isobutanal leaving the reactor)/(iso-butanol converted in the reactor),

[0178] The C3's cut purity is the ratio, on carbon basis, (propylene leaving the reactor)/(propylene+propane leaving the reactor). It means the propylene purity is the percentage of propylene, on a carbon basis, present in the C.sub.3 cut, containing close-boiling compounds, recovered in the stream leaving the reactor.

[0179] The following notations were used:

[0180] C3=:propylene,

[0181] C4=:C4 olefin,

[0182] i-BuOH:iso-butanol,

[0183] i-butanal:iso-butanal (iso-butyraldehyde).

Example 1

[0184] A catalyst composition was produced by extrusion of 50 g of Nyasil 20 (Nyacolan amorphous silica powder) with 45 g of silica sao Ludox HS-40 (SiO.sub.2 40 wt %, W. Grace). The obtained extruded body was dried for 24 h at room temperature, dried for 24 h at 110 C., and calcined at 500 C. for 6 h in static air with a heating rate of 1 C./min.

[0185] The sample is hereinafter identified as A (TPD NH.sub.3 30 mol/g, TPD CO.sub.2 42 mol/g).

Example 2 (Comparative)

[0186] 50 g of MgCO.sub.3 (Aldrich) was calcined at 600 C. for 10 h (1 C./min heating rate) to produce MgO. The 21 g of the synthesized MgO was extruded with 22.5 g of silica sol Ludox HS-40 (SiO.sub.2 40 wt %, W. Grace). The obtained extruded body was dried for 24 h at room temperature, dried for 24 h at 110 C. and calcined at 500 C. for 6 h in static air with a heating rate of 1 C./min.

[0187] The sample is hereinafter identified as B (TPD NH.sub.3 75 mol/g TPD CO.sub.2 383 mol/g).

Example 3

[0188] 20 g of the sample A (TPD NH.sub.3 30 mol/g, TPD CO.sub.2 42 mol/g) was incipient wetness impregnated with 1.005 g of Pd(NO).sub.32H.sub.2O to introduce 2 wt % of Pd to the sample. The impregnated sample was maturated during 2 h at room temperature, dried for 24 h at 110 C. and calcined at 500 C. for 6 h in static air with a heating rate of 1 C./min.

[0189] The sample is hereinafter identified as A1.

Example 4

[0190] 20 g of the sample A (TPD NH.sub.3 30 mol/g, TPD CO.sub.2 42 mol/g) was incipient wetness impregnated with a solution containing 0.5 g AgNO.sub.3 and 8.88 g Ni(NO.sub.3).sub.26H.sub.2O to introduce 0.5 wt % of Ag and 6 wt % Ni over the sample. The impregnated sample was maturated during 2 h at room temperature, dried for 24 h at 110 C., and calcined at 500 C. for 6 h in static air with a heating rate of 1 /min.

[0191] The sample is hereinafter identified as A2.

Example 5

[0192] 30 g of the sample A (TPD NH.sub.3 30 mol/g, TPD CO.sub.2 42 mol/g) was incipient wetness impregnated with 0.15 g of Pd(NO).sub.32H.sub.2O to introduce 0.2 wt % of Pd to the sample. The impregnated sample was maturated during 2 h at room temperature, dried for 24 h at 110 C., and calcined at 500 C. for 6 h in static air with a heating rate of 1 C./min.

[0193] The sample is hereinafter identified as A3.

Example 6

[0194] 30 g of the sample A (TPD NH.sub.3 30 mol/g, TPD CO.sub.2 42 mol/g) was incipient wetness impregnated with a solution containing 0.5 g AgNO.sub.3 and 0.15 g of Pd(NO).sub.32H.sub.2O to introduce 1 wt % of Ag and 0.2 wt % of Pd over the sample. The impregnated sample was maturated during 2 h at room temperature, dried for 24 h at 110 C., and calcined at 500 C. for 6 h in static air with a heating rate of 1 C./min.

[0195] The sample is hereinafter identified as A4.

Example 7 (Comparative)

[0196] 20 g of the sample B (TPD NH.sub.3 75 mol/g, TPD CO.sub.2 383 mol/g) was incipient wetness impregnated with a solution containing 0.5 g AgNO.sub.3 and 0.15 g of Pd(NO).sub.32H.sub.2O to introduce 1 wt % of Ag and 0.2 wt % of Pd over the sample. The impregnated sample was maturated during 2 h at room temperature, dried for 24 h at 110 C., and calcined at 500 C. for 6 h in static air.

[0197] The sample is hereinafter identified as B1.

Example 8 (Comparative)

[0198] 5 g of the sample A1 (2 wt % Pd/SiO.sub.2) was incipient wetness impregnated with 0.1 g Na.sub.2S (0.7 ml H.sub.2O/1 g of solid, Pd/S atomic ratio 0.74, Na/Pd 2.7). The impregnated sample was maturated during 2 h at room temperature, dried for 16 h at 120 C.

[0199] The sample is hereinafter identified as A5 (TPD NH.sub.3 42 mol/g, TPD CO.sub.2 146 mol/g).

Example 9 (Comparative)

[0200] 15 g of the A1 (2 wt % Pd/SiO.sub.2) was incipient wetness impregnated with 2.2 g of Pd(NO).sub.32H.sub.2O to produce a sample containing 5 wt % of Pd to the sample (0.8 ml H.sub.2O/1 g solid). The impregnated sample was maturated during 2 h at morn temperature, dried for 24 h at 110 C., and calcined at 500 C. for 6 h in static air with a heating rate of 1 C./min.

[0201] Then, the calcined sample was reduced in H.sub.2 flow (10 Nl/h) for 3 h at 450 C.

[0202] The total amount of the produced sample after reduction with hydrogen was incipient wetness impregnated with 0.3 g Na.sub.2S+0.1 g NaOH (0.7 ml H.sub.2O/1 g solid, Pd/S atomic ratio 2.92, Na/Pd 0.85, 2.8 wt % S). The impregnated sample was maturated during 2 h at room temperature, dried for 16 h at 120 C.

[0203] The sample is hereinafter identified as A6 (TPD NH.sub.3 25 mol/g, TPD CO.sub.2 143 mol/g).

Example 10

[0204] Catalytic test was performed in a down flow stainless-steel reactor tube with an internal diameter of 11 mm. 4 g of crushed catalyst (35-45 mesh) was loaded. The reactor temperature was increased at a rate of 60 C./h to 450 C. under nitrogen flow 10 Nl/h. Then the catalyst was treated for 1 hour at 450 C. in nitrogen followed by reduction in di-hydrogen flow 10 Nl/min for 2 h at atmospheric pressure. Afterwards the reactor was purged with nitrogen followed by cooling down to the reaction temperature in nitrogen flow and pressurization if it was required with nitrogen.

[0205] Analysis of the products is performed by using an on-line gas chromatography.

Example 11

[0206] Catalyst test according to the example 10 was performed with a pure iso-butanol as feed on catalysts A1, B1, A6.

[0207] The conditions and results are gathered in table 1.

TABLE-US-00001 TABLE 1 T, C. 375 375 375 A1 B1 A6 invention comparative comparative WHSV, h.sup.1 1 1 1.6 Pressure, barg 5 5 0.5 Conversion of i-BuOH, % 15.4 9.2 6.3 Selectivity on C-basis, % Decarboxylation (C3=) 2.3 2.9 1.6 Dehydration (C4=) 8.8 20.2 4.8 Iso-butanal 79.2 53.6 58.7 heavies 9.7 23.3 34.9

[0208] The example demonstrates a possibility to produce iso-butyraldehyde and propylene directly from iso-butanol. However, basic support (MgO catalyst B1) or post-synthetic modification with basic compounds (Na catalyst A6) leads to significantly higher amount of heavies due to side reactions. This shows that the use of non-basic type of catalyst permits reducing the amount of heavies, which are supposed to be formed via side reaction between butyraldehyde and non-reacted butanol in direct transformation or at the step of butanol conversion to butyraldehyde in the first reaction zone of a two stage process.

Example 12 (Iso Butyraldehyde Formation from Isobutanol)

[0209] Catalytic test was performed in a quartz reactor of 5 mm internal diameter. Before the test, catalyst has been activated in situ for 1 h at 500 C. (2 C./min) in flow of He (50 ml/min). Isobutanol of 99% purity from Sigma-Aldrich has been used (0.806 g/ml density @15 C.; 0.085 wt % H.sub.2O; 8 ppm S). The feed was sent to the reactor via a thermostatic saturator containing isobutanal at 75 C. at a pressure close to atmospheric (1.1 bar). The test was performed on 0.5 g of crushed Fe.sub.2O.sub.3 catalyst (>99%, Sigma Aldrich, 35-45 mesh), at weigh hour space velocity 9.4 h.sup.1 in a temperature range from 100 to 550 C.

[0210] FIG. 3 shows the evolution of selectivity of the products formed as a function of the temperature.

[0211] The example demonstrates feasibility of iso-butyraldehyde production from iso-butanol.

Example 13 (Iso-butyraldehyde and Propylene Formation from Iso-butanol)

[0212] Catalytic test was performed in a quartz reactor of 5 mm internal diameter. Before the test, catalyst has been activated in situ for 1 h at 500 C. (2 C./min) in flow of He (50 ml/min). Iso-butanol of 99% purity from Sigma-Aldrich has been used (0.806 g/ml density @15 C.; 0.085 wt % H.sub.2O; 8 ppm S). The feed was sent to the reactor via a thermostatic saturator containing iso-butanol at 75 C. at a pressure close to atmospheric (1.1 bar). The test was performed on 0.5 g of activated carbon catalyst (granulated, Sigma Aldrich, 35-45 mesh), at weigh hour space velocity 9.4 h.sup.1 in a temperature range from 100 to 550 C.

[0213] FIG. 4 shows the evolution of selectivity of the products formed as a function of the temperature.

[0214] The example shows a possibility to produce iso-butyraldehyde and propylene directly from iso-butanol. It's evident that the iso-byraldehyde is a true intermediate product in the reaction.

Example 14

[0215] Catalyst test according to the example 10 was performed with a pure iso-butanal as feed on the catalysts A1 (300 C., atmospheric pressure, WHSV-1 h.sup.1) and A2 (300 C., 5 bars, WHSV-1 h.sup.1).

[0216] The results are gathered in table 2.

[0217] The data illustrate that both catalysts may be used to transform iso-butanal to propylene. However, Ni-containing catalyst (A2) is slightly less efficient. In order to reach the same conversion level, more severe conditions are required.

TABLE-US-00002 TABLE 2 Catalyst A1 A2 Conversion, % 54 50 Selectivity on C-basis, % Decarbonylation (C3H6 + C3H8) 96 78 Hydrogenation (Iso-butanol) 1 14 Oxidation (butanoic acid) 2 2 Heavy products (condensation) 2 6

Example 15

[0218] Catalyst test according to the example 10 was performed with a pure iso-butanal as feed on the catalysts A1 under different operating conditions C1, C2, C3, C4. Results are given in table 3. The different conditions and results are gathered in table 3. All the tests have been performed for 1 week. It was observed stable results for all the duration of the tests.

TABLE-US-00003 TABLE 3 Operating conditions C1 C2 C3 C4 WHSV, h.sup.1 1 1 2 4 T, C. 250 300 300 300 P, barg 0.5 0.5 0.5 0.5 H.sub.2/CO 0.67 0.63 0.66 0.7 C3 =/(H.sub.2 + butanol) 1.03 0.98 1.05 1.0 Conversion, % 18 52 54 48 decarboxylation 90 94 94 96 C3 purity, % 76 70 78 85 Iso-butanol <0.5 2 1 1 butanoic acid 10 2 4 3 Heavy products <0.5 2 1 0.2

[0219] Analysis of the products is performed by using an on-line gas chromatography. The GC analysis of the products show two major peaks corresponding to propylene and iso-butanal, and small peaks corresponding to unreacted iso-butanol, n-butanol, i-butanoic acid, heavy compounds. Di-butyl ether and iso-butyl iso butinate are also observed.

Example 16 (Comparative)

[0220] Catalytic test was performed in the down flow stainless-steel reactor tube with an internal diameter of 11 mm. 2 g of crushed catalyst (35-45 mesh) was loaded. The reactor temperature was increased at a rate of 60 C./h to 450 C. under nitrogen flow 10 Nl/h. Then the catalyst was treated for 1 hour at 450 C. in nitrogen followed by reduction in di-hydrogen flow 10 Nl/min for 2 h at atmospheric pressure. Afterwards the reactor was purged with nitrogen followed by cooling down to the reaction temperature in nitrogen flow.

[0221] Analysis of the products is performed by using an online gas chromatography.

[0222] Catalyst A5 was used for the reaction.

[0223] The results are given in table 4.

TABLE-US-00004 TABLE 4 T, C. 325 WHSV, h.sup.1 1.6 Pressure, barg 0.5 feed EFFLUENT feed EFFLUENT Composition, wt % C-basis Decarboxylation (C3) 2.2 3.6 Dehydration (C4) 0.3 0.5 Iso-butanal 25 21.9 50 44.1 iBuOH 75 64.9 50 47.3 others 10.7 4.4 Conversion of iButanal, % 12.5 11.9 Conversion of i-BuOH, % 13.5 5.4 Selectivity, wt % C-basis Decarboxylation (C3=) 8.5 20.9 Dehydration (C4=) 1.2 3.4 others 90.4 75.7

[0224] The data show that the catalyst modified with sulfur shows low activity in decarbonylation and the presence of the sodium (basic function) leads to high amount of heavies when both iBuOH and iButanal are present in the reaction mixture.