BE602415A - - Google Patents

Description

       

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  DD / TTTI? ' i7nrrn T tr., r, ...... "t ....., #; -.:, PROCESS .., .....: .... I3 ivW .siïcüiViv ü ïil.LLL1 ' ltLLnJ = '

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The present invention relates to a process for the hydrogenation of aldehydes and, more particularly, to a process for preferentially hydrogenating aldehydes in a mixture containing aldehydes and olefins.



   In the first stage or hydroformylation stage of the Oxo process, a hydroformylation of olefins is carried out.



    This reaction, which is also known under the name of "carbonylation" or "oxonation", consists in reacting olefins with carbon monoxide and hydrogen, so as to form aldehydes. Other organic reaction products, such as alcohols and acetals, are also produced. The stream from the hydroformylation step contains aldehydes, other reaction products, as well as unreacted hydrogen, carbon monoxide and olefins.



   In the second stage or hydrogenation stage of the Oxo process, the aldehydes obtained during a hydroformylation stage are converted into alcohols and other oxygenated products are also formed. However, in the processes previously proposed for the hydrogenation of aldehydes to alcohols in a mixture also containing olefins, a significant proportion of the olefins were hydrogenated to paraffins, so that a mixture of hydrocarbons was obtained. or a hydrocarbon fraction of the arogenated products consisting of a relatively small amount of unconverted olefins and a relatively large amount of paraffins.

   It is desirable and to prevent this = The conversion of olefins to paraffins in the hydrocarour fraction, because if the olefins contained in this traction are not hydrogenated, the process efficiency exe

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 can be improved by recovering the olefins from the products emanating from the hydrogenation stage and using them as such or by recycling them. The present reversal relates to a process for selectively hydrogenating aldehydes in the presence of olefins, while applying usual hydrogenation pressures, such as pressures between 100 and 1000 pounds per square inch.



   The Applicant has found that aldehyaes mixed with olefins can be hydrogenated into alcohols, while a hydrocarbon fraction. consisting mainly of olefins can be produced by introducing water into a mixture of aldehydes and olefins, then hydrogenating the resulting mixture in the presence of the added water, on a catalyst acting at low temperatures, for example at temperatures below 500 F. When operating in this manner, the aldehydes are converted into alcohols and a hydrocarbon fraction consisting mainly of olefins is obtained. The olefins can be easily separated from the alcohols and used again in a hydroformylation step.

   Applicants have found that it is important to carry out the process at a relatively low temperature, because otherwise the olefins are hydrogenated with the aldehydes. On the other hand, it is important to use a catalyst which constitutes an efficient hydrogenation catalyst at low temperatures, because when operating at a low temperature with a catalyst which has maximum activity at high temperature, for example. 800 to 1000 F, only a very weak hydrogenation of the aldehydes or olefins occurs.

   Moreover, when an attempt is made to operate at high temperatures, using a catalyst effective at such temperatures, the effect of temperature so distorts the effect of the water added that the hydrogenation of the olefins is not. not noticeably prevented.

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  As mentioned above, the process according to the present invention is advantageously carried out at temperatures below 500 F. Preferred results are obtained at temperatures below 450 F. It is possible to apply, for example, temperatures between 300 and 450 F approximately and, in particular, temperatures between approximately 350 and 400 F.
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  With regard to the e - catalysts used, it can be said that in general all catalysts which operate at low temperature can be suitable. Hydrogenation catalysts which operate at low temperature are well known in the art and it is clear that a few here as examples. Among these? preferred catalysts are nickel, cobalt, nickel and tungsten sulfides, cobalt molybdate and copper chromium. The catalyst can be in the form of pellets or granules and it can be placed in the hydrogenation zone as such. However, generally better results are obtained by depositing the catalyst on a support, such as diatomaceous earth or kieselguhr.



   The water can be introduced in the liquid phase or in the vapor phase in the mixture of aldehydes and olefins, before or after introduction of the mixture into the hydrogenation zone. Ordinarily, when the hydrogenation is carried out at an elevated pressure, for example at a pressure of 1000 pounds per square inch, it is more convenient to introduce the water in the liquid phase and to heat the mixture of hydroformylation products. water at the desired hydrogenation temperature. A part of the water can be introduced at room temperature, in liquid phase, into the hydrogenation reactor, at intervals distributed in the direction of flow in the reactor.

   In this way,

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 the temperature can be controlled in the reactor, because the heat of hydrogenation is dissipated to vaporize and heat the water to the temperature of hydrogenation.



   The mixture of aldehydes and olefins which is preferably hydrogenated by the process according to the present invention can be obtained in a number of ways, but it is usually obtained by extraction of carbon monoxide, hydrogen. and catalytic metals of a
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 stream from a hydroformylation reaction in an Oxo process. The mixture in question will therefore hereinafter be referred to as "hydroformylation products".



   The amount of water charged with the hydroformylation products to the hydrogenation zone can vary. It is preferable to use as little water as possible, the advantages of the present invention being realized even with a very small amount of water, because such an amount results in the most efficient operation. of the hydrogenation reactor. Volumetric ratios of water to hydroformylation products charged of 0.15: 1 to 2: 1 give good results and best results are obtained with an inclusive ratio. between about 0.1: 1 and 0.5: 1.



   A particular and preferred embodiment of the process according to the present invention will now be described by way of example, with reference to the appended drawing, the single figure of which shows schematically an installation for carrying out the following process. invention.



   A synthesis mixture consisting of carbon monoxide and hydrogen is introduced through line 3, while a mixture of olefins and a hydroformylation catalyst, usually consisting of an iron or cobalt catalyst , is brought by a pipe 4, into a hydroformylation zone 6. Olefins and syngas

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 are reacted and the metal salts or metal catalytic carbonyls are separated. Hydroformylation products containing unreacted aldehydes, other reaction products and olefins, at a pressure of about 500 pounds per square inch and a temperature of about 150 F, are discharged from the zone. hydroformylation by a line 7.

   Water is introduced through a pipe 8 into a pump 9, from where it is supplied under a pressure
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 of about> uu pounds per square inch, through line 11, in hydroformylation products. The resulting mixture of water and hydroformylation products is fed through line 12 into a heat exchanger 13, in which the mixture is heated to a temperature of about 400 F.



  The heated mixture is then brought from the heat exchanger 13 through a line 14 into a hydrogenation reactor 16. This reactor 16 contains a number of baskets 17a to 17f, which are filled with nickel pellets 18 on Kieselguhr d. 'a diameter of one eighth of an inch. The pellets which contain approximately 44% nickel in the original state can be used in the form of oxide after calcination or can be partially reduced to 900 F, by passing hydrogen over them for 4 hours at atmospheric pressure, at a flow rate of about 635 volumes of hydrogen per hour per volume of catalyst.



   After preparation of the catalyst, hydrogen is brought to a pressure of about 500 pounds per square inch through line 19 to heat exchanger 20 in which this hydrogen is heated to a temperature of about 400 F. L The heated hydrogen is introduced through a pipe 21 to the upper part of the hydrogenation reactor 16.



  The mixture of hydroformylation products, water and hydrogen passes downward into hydrogenation reactor 16, the aldehydes contained in this reactor reacting with hydrogen to form alcohols.

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   Additional hydrogen at a pressure of about 500 pounds per square inch and a temperature of about 100 F is introduced, below the baskets containing the catalyst, into the hydrogenation reactor through an inlet line. 19 and a pipe 22, as well as a system ae parallel pipes 23a to 23e equipped with valves. The quantity of hydrogen passing through the heater and through the various pipes is determined.
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 - w Rà9 <to heat the hydrogen and the temperature of the hydrogenation reactor is set to about 400 F. At the lower part of the hydrogenation reactor, substantially all the aldehydes have been transformed into alcohols, but the olefins n 'were not substantially hydrogenated.



   The products of the hydrogenation reaction are discharged from the lower part of the reactor through a line 26 and are fed into a heat exchanger 27, in which they are cooled to a temperature of about 120 F. The products of Cooled hydrogenations are fed through line 28 to a pressure reducing valve 29, where their pressure is reduced from about 500 pounds per square inch to substantially atmospheric pressure.



  The cooled hydrogenation products are then fed through a line 31 into a hydrogen separation tower 32. The hydrogen is discharged from the upper part of this tower through a pipe 33 and discharged from the system through a pipe 34. This hydrogen can then be used as a fuel or, if desired, it can be recycled through line 36, pump 37 and valve line 38 into the hydrogen inlet line 19.



   The hydrogen-free mixture is then evacuated from the tower 32 via a pipe 41 and introduced into a water separator 42. A fraction of water is discharged from the bottom, via a pipe 43. This fraction of water is sent back. in

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 the water inlet pipe 8 via a pipe 44, which contains a circulation pump 46 and a valve 47. In the event that impurities, such as iron oxide, are deposited in the pipe 44, the all or part of the aqueous fraction can be discharged through a pipe 48 provided with a valve. When the accumulation of impurities is a problem, some of the water is preferably continuously removed from the system.



   A fraction containing hydrogenation products is removed or discharged at the upper part of the water separator 42 via a pipe 51 and fed into a separator device 52. A fraction containing hydrocarbons consisting mainly of olefins water discharged from the separator 52 by a line 53. This hydrocarbon fraction can be returned to the olefin inlet line 4 via a line 54 containing a valve 55 and a recycle pump 56. Well, if desired, this fraction can be discharged by a pipe-57, in which is mounted a valve 58.

   The fractions of the hydrogenation products, the boiling points of which are lower and higher than those of the hydrocarbons, are fed through lines 61 and 62 into additional separating devices, which are not shown.



   To compare the results obtained when operating by the process according to the invention, and when operating outside the scope of the invention, the results obtained in
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 During the course of two tests each carried out during a certain number of hydrogenation periods are given in Table I below. During these periods, the hydrogenation was carried out in a hydrogenation reactor consisting of a steel pipe with an inside diameter of 0.824 inch, surrounded by a chimney containing boiling water which had
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 eL4 91nene 4vv0.

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   The hydrogenation reactor was charged with about 585 milliliters of 1/8 inch pellets of nickel on Kieselguhi-, so as to form a layer about 6 feet in length. The catalyst contained approximately 44% nickel in its original state and 70% nickel, after calcination at 1000 F and reduction at 900 F.



   The pressure was maintained at 500 pounds per square inch during these times. The feed used in each period consisted of hydroformylation products from the same hydroformylation run, for which heptenes had been used. The hydroformylation products contained 43.0% oxygenated material consisting primarily of aldehydes and 57% hydrocarbons consisting of about 95% olefins. The olefins in the feed thus constituted about 55.2% by weight of the feed.



   The hydroformylation products were charged to the top of the hydrogenation reactor. Water was in some cases also charged to the top of the reactor. The hydrogenation products were vented from the bottom of the hydrogenation reactor, after which their pressure was reduced, as was their temperature. A fraction of the hydrogenation products from each run was analyzed to determine the proportion of unconverted aldehydes contained in the hydrogenation products.

   Another fraction of the hydrogenation products from each run was distilled, so as to obtain a fraction containing all the oxygenates and a hydrocarbon fraction containing the unconverted olefins and paraffins produced by hydrogenation of the olefins. Each hydrogenation fraction was then distilled to form a sub-fraction containing alcohols and aldehydes and a sub-fraction.

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 of residue. The percentage of alcohol was then determined by subtracting the previously determined percentage of alahydes from the total percentage of alkols and aldehydes contained in this sub-fraction.

   The hydrocarbon fractions were analyzed to determine the percentage of olefins, by measuring the bromine number. In the following table, the proportions of oxygenates, aldehydes, alcohols, residue, dehydrocarbons and olefins are all given in percent relative to the total weight of the hydrogenation products: The efficiency of olefin retention in the product obtained was determined by dividing the percentage of olefins: contained in the feed by the percentage of olefins contained in the products and multiplying by 100.



  This does not take into account the small change in weight of the hydrogenation products caused by the addition of hydrogen.



   The boneless results are given in the following table. The percentage by weight of olefins contained in the hydrocarbon fraction is given in the lower part of Table I, to show the extent to which the hydrogenation of the hydrocarbon fraction is reduced, when operating in accordance with the present invention.

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    TABLE I
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 ht3.r '1 ±' 1 'CUI, 0J T10Nd DE. # AC'I1ùN
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<tb> Period <SEP> 1 <SEP> Period <SEP> 2 <SEP> Period <SEP> 3
<tb> Test <SEP> Test <SEP> Test <SEP> Test <SEP> Test <SEP> Test
<tb> 1 <SEP> 2 <SEP> 1 <SEP> 2 <SEP> 1 <SEP> 2
<tb> Water, <SEP> ml / hr. <SEP> 0 <SEP> 0 <SEP> 100 <SEP> 100 <SEP> 250 <SEP> 250
<tb>
 
 EMI11.3
 Hydroformylation products, ml / hr.

   500 500 500 500 500 500
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<tb> Hydrogen, <SEP> <SEP> cubic feet / hour <SEP> 35 <SEP> 35 <SEP> 35 <SEP> 35 <SEP> 35 <SEP> 35
<tb> Total <SEP> pressure, <SEP> pounds / inch <SEP> square <SEP> 500 <SEP> 500 <SEP> 500 <SEP> 500 <SEP> 500 <SEP> 500
<tb> Temperature, <SEP> jacket <SEP> of the <SEP> reactor, <SEP> F <SEP> 400 <SEP> 400 <SEP> 400 <SEP> 400 <SEP> 400 <SEP> 400
<tb> temperature, <SEP> zone <SEP> hot <SEP>, F <SEP> 405 <SEP> 406 <SEP> 403 <SEP> 404 <SEP> 404 <SEP> 404
<tb>
 
 EMI11.5
 G0MP00rrlONd UEd HYDROGENATION PRODUCT j
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<tb> oxygenated <SEP> materials,% <SEP> in <SEP> weight <SEP> of <SEP> products
<tb> hydrogenation.

   <SEP> 40.0 <SEP> 41.0 <SEP> 43.0 <SEP> 42.5 <SEP> 42.5 <SEP> 44.0
<tb> Aldehydes, <SEP> in <SEP> weight <SEP> of <SEP> hydrogenation <SEP> products <SEP> 3.9 <SEP> 3.3 <SEP> 1.6 <SEP> 2, 3 <SEP> 3.4 <SEP> 3.5
<tb>
 
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 Alcohols,, Cl Il "" "il 22.1 24.2 33.9 3412 31.6 z5 Residue" "" il tt n 14eO 13.5 7.5 6.0 7.5 7.0 Hydrocarbons 70 "" ".. n 60.0 59.0 57.0 57.5 57.5 56.0 Olefins% in" "" ¯¯¯¯ "il 31.9 36.9 36.2 39.7 48, $ '., 0
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<tb> EFFICIENCY <SEP> OF <SEP> RETENTION <SEP> OF OLEFINES
<tb> olefins <SEP> not <SEP> transformed <SEP> into <SEP> paraffins, <SEP> 56.0 <SEP> 64.8 <SEP> 63.5 <SEP> 69.6 <SEP> 85, 7 <SEP> 86.0
<tb>
 
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 doyenne olefins not transformed into 'araffins, 60 4. 66 5 85e8 KEPARTJTIOM UEc, 01> lfi'iNfli DANI FIIACT10N HYU OC 8 {;:

  ) - datis hydrocarbon fraction, by weight 53.2 62.3 63.5 69, o P5, P7, f)
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<tb> dean <SEP> olefins <SEP> dais <SEP> fraction <SEP> hydrocarbons,; .. <SEP> weight <SEP> 57.7 <SEP> 69 <SEP> 86.3
<tb>
 

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 A review of the results of the tests given in Table I, in which a hydroformylation product loading space velocity of 1.17 was employed in each test, reveals that the addition of 0.2 liters of water per liter of hydroformylation product. Hydroformylation products caused an increase in the average percentage of olefins in the hydrocarbon fraction from 57.7- to 66.2%. The addition of 0.5 liters of water per liter of product of hy-
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 Droformylation also increased the average percentage of olefins to 86.3%.



   The advantages of the invention, as regards the preferential hydrogenation of aldehydes in a mixture of aldehydes and olefins, as well as the production of a hydrocarbon fraction consisting essentially of olefins, can be obtained, even if we change the operating conditions indicated in Table I. The data collected during a series of tests (see table 2), in which the hydroformylation products were made to pass over 200 ml of a catalyst similar to that used for the tests referred to in Table 1, but which was somewhat more efficient for the conversion of alcohols are the subject of Table 2.

   During these test periods, a space velocity of loading of the hydroformylation products ae C1.5 was applied, while the volume ratio of water to hydroformylation product loaded was 0.5: 1. The load and the products were analyzed in the same way as for the tests mentioned in Table 1.

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 rlo [, Pt.l'I'TON Pii.,.) JITi TAHLAU 2.

   Zoned DTIYI) ROGENATIOM 1 en! D'n \! 'nON I)': 'Pii; j.> Ji'1'ô v * HYùR0i "vK.tYLkl'īoil cH>; itiiiiJ Url, 3 HYDROGENATION 40Ni -... -
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 - f - '{rl0ae 4 rrloae 7
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<tb> Oxygenated <SEP> materials, <SEP> /, <SEP> poias <SEP> load <SEP> 55.0 <SEP> 55.0
<tb> Aldehydes <SEP> "<SEP>" <SEP> "<SEP> 46.9 <SEP> 46.9
<tb> Hydrocarbons <SEP> "<SEP>" <SEP> "<SEP> 45.0 <SEP> 45.0
<tb>
 
 EMI13.4
 Olefins fi "" 'ruz + 2,%!?, 7
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<tb> RATE <SEP> AND <SEP> CONDITIONS <SEP> OF <SEP> REACTION
<tb> Water, <SEP> ml / hrs <SEP> 50 <SEP> 50
<tb> Hydroformylation <SEP> products, <SEP> ml / hrs <SEP> 100 <SEP> 100
<tb> Hydrogen, <SEP> cubic feet <SEP> / hour <SEP> 3.2 <SEP> 3.2
<tb> Total <SEP> pressure, <SEP> pounds / inch <SEP> square <SEP> 500 <SEP> 500
<tb> Temperature, <SEP> jacket <SEP> of the <SEP> reactor, F <SEP> 365 <SEP> 385
<tb> Temperature,

   <SEP> hot <SEP> zone <SEP> F <SEP> 375 <SEP> 395- <SEP> 405
<tb>
 
 EMI13.6
 C014POSITION OF HYDROGENATION PRODUCTS
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<tb> Oxygenated <SEP> materials,% <SEP> in <SEP> weight <SEP> of the <SEP> hydrogenation <SEP> products <SEP> 54.0 <SEP> 52.5
<tb>
 
 EMI13.8
 Aldehydes, fi Tt n "tt" il 3,4 1, 2 Alcohols, rr, r rr fi rr Il "39,1 .4.1a., $ Residue, fi fi It fi rt fi fi," 11, 5 6, 5 Hydrocarbons, il fi fi rf il '16.0 47.5 Olefins, Il fi "fi fi fi" 37.4 41.5 OLEFIN RETENTION EFFICIENCY Olefins not transformed into paraffins, / a $ ?, 7 g7, 1
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<tb> DISTRIBUTION <SEP> OF <SEP> OLEFINS <SEP> IN <SEP> FRACTION <SEP> HYDROCARBONS
<tb>
 
 EMI13.10
 Olefins in hydrocarbon fraction, wt% ,,, <8] .; 2, $ 7 = ..,, .. '; :::; <<. z.



  . j. $ ";.] i? Î%;

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 The advantages of the present invention, in particular the preferential hydrogenation of aldehydes in a mixture of aldehydes and olefins, can be obtained by modifying still in other respects the conditions described in the two tables. Thus, space velocities other than 0.5 or 1.17 may be used. The hydrogenation can be carried out at any pressure between about 100 and 1000 English pounds per square inch.

   Other effective catalysts
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 at low temperatures, eg temnratjzr.s below 500 F, can be used: The best results are obtained at hydrogenation temperatures below 450 F, especially at temperatures between 300 and 450 F and, in particular, between 350 and 400 F, with catalysts of nickel sulfide, cobalt, nickel and tungsten, cobalt molybdate and copper chromite. The volumetric ratios of water to hydroformylation products between 0.15: 1 and 2: they give good results, the best results being obtained with ratios between 0.20: 1 and 0.5: 1 in volume.



   When the present invention is applied in conjunction with a hydroformylation reaction, it offers the additional advantage of allowing the recovery of an olefin stream from the hydrogenation stage which is richer in non-terminally linked olefins than the original stream. used at the hydroformylation stage.



  This occurs because the olefin stream from the hydroformylation stage is richer in non-terminally linked olefins than the stream fed to the hydroformylation stage and because when the products from the hydroformylation stage are hydrogenated by the process according to the present invention, it is the aldehydes which are preferably hydrogenated, while the hydrocarbons contained in the hydrogenation products consist essentially of olefins.

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   It is obvious that numerous modifications and variations are possible in the implementation of the method according to the invention, without departing from the scope thereof, as defined in the following claims.



    CLAIMS.



  1.- Process for preferentially hydrogenating aldehydes in a mixture of aldehydes and olefins, characterized in that this mixture is subjected to a hydrogenation in the presence
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 ...-.-.....- 0 '0 "- --jyw' y '' 'WWàWJUWWI' ± QUC" 'to Q nifl -J ::' J :: '.., V ... L \ .Wlt :: IJ.L'.l.y'ue ù.! .¯ Cive
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 water to the mixture of aldehydes and olefines' r3.s between 0.15: 1 r .f.a. ! 1'r; i.,. .....,: 'J "" 1 ..' \ t t ,,;: and about 2: 1 in the liquid state, on a low temperature hydrogenation catalyst, at a temperature of about 300
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 ...> 1 ".- 500 F. to 500 F. ,, 1 '1.



  2.- Process for preferentially hydrogenating aldehydes in a mixture of aldehydes and olefins, characterized in that said mixture is subjected to hydrogenation in the presence of a certain amount of added water ', this amount being such that the volumetric ratio of water to the mixture of aldehydes and olefins in the liquid state is between about 0.15: 1 and about 2: 1, on a nickel catalyst at a temperature of d 'about 300 to about 500 F.



  3. - Process for preferentially hydrogenating al- aéhyàes in a mixture of alahydes and olefins, characterized in that said mixture is subjected to a hydrogenation in the presence of a certain quantity of added water, this quantity. being such that the volume ratio of water to the mixture of aldehydes and olefins in the liquid state is between about 0.15: 1 and 2: 1, over a cobalt catalyst, at a temperature of about 3CC at around 500 F.

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Claims (1)

4.- Process for preferentially hydrogenating al- ahyàes in a mixture of aldehydes and olefins, characterized in that said mixture is subjected to hyarogenation in the presence of a certain quantity of added water, this quantity. EMI15.4 being such that the volumetric ratio of water to the mixture of aldehydes and olefins in the liouiae state is co. caught between <Desc / Clms Page number 16> EMI16.1 eix., iron, ù, 15: 1 and about 2: 1 ,,., ur a <"'\ t.alyeL.Lr of sulphide rse nickel and ae tungsten, z a temperature :: 1tln dtellviron" <1 At about 500 F. EMI16.2 5.- Process for preferentially hydrogenating alaényaes aanj a mixture of aldehydes and o11finea, characterized in that said mixture is subjected to una hydrogenation in the presence of a certain quantity of added water, this quantity of water being such that the volumetric ratio of water to the mixture of aldehyde and olefins in the liquid state is between about 0.15: 1 and about 2: 1, on a cobalt molybdate catalyst, at a temperature of d 'about 300 to about 500 F. 6. - A process for preferentially hydrogenating aldehydes, in a mixture of aldehydes and olefins, characterized in that said mixture is subjected to hydrogenation in the presence of a certain amount of added water, this amount of water being such that the volumetric ratio of water to the mixture of aldehydes and olefins in the liquid state is between about 0.15: 1 and about 2: 1, on a copper chromite catalyst, at a temperature between about 300 and about 500 F. 7.- Process for preferentially hydrogenating aldehydes in hydroformylation products originating from a reaction. EMI16.3 tion of hydroformylation, characterized in that water is introduced into said hydroformylation products in an amount such that the volumetric ratio of water to hydroformylation products in the liquid state is approximately 0.2: 1 to 0.5: 1, hydrogen is passed with the mixture of water and products EMI16.4 hydrofor'nylation at a temperature of about 350 to about 400 F in a hydrogenation zone containing a nickel catalyst, the hydrogenation products obtained are discharged, they are EMI16.5 3pse loe, 5 olfi7es and these olefins are recycled to the hydro- EMI16.6 ..I, .V ..h: J ...... '-' .. LV.!.!.