FR2474024A1 - PROCESS FOR PRODUCING BUTENE-1 FROM A C4 CUTTING OF HYDROCARBONS - Google Patents

Abstract

PRODUCTION OF BUTENE-1 FROM A C-SECTION OF HYDROCARBONS. CUP C IS FIRST REACTED WITH AN ALCOHOL TO CONVERT ISOBUTENE INTO METHYL TERTIOBUTYL ETHER; THE RESULTING CUP C IS SUBJECTED TO SELECTIVE HYDROGENATION THEN TO FRACTIONING ALLOWING TO OBTAIN A CUT RICH IN BUTENE-1, WHICH IS THEN SUBJECTED TO EXTRACTION BY SOLVENT. THUS IS OBTAINED BUTENE-1 WITH A HIGH DEGREE OF PURITY.

Description

The invention relates to a process for producing butene-1

  from a C4 hydrocarbon cut.

  Of the mono-olefins in C4, butene-1 is of interest

  particular. In fact, its polymerization makes it possible to obtain polybutene

  1 which is one of the few polymers to retain good resistance to high temperatures and so be used in manufacturing

  hot water pipes for the building industry.

  Butene-1 is also used as a comonomer in some

  ethylene polymerization processes leading either to the production of

  high density polyethylene or to obtain polyethylene

low density at low pressure.

  So far, unfortunately, because of its high price,

  butene-1 failed to develop on a large scale.

  The object of the present invention is to describe a chain of

  butene-1, which is as effective as it

  this compound at a truly competitive price.

  C4 cuts of hydrocarbons of particular interest to

  the invention are those which, from a conver-

  of olefins, followed by an extraction of at least most of the 1,3-butadiene, contain at least one

  C4 saturated hydrocarbon (n-butane and optionally isobutane), hy-

  monoolefinic hydrocarbons (butene-1, butene-2 and isobutene) and at least one diolefinic hydrocarbon (in particular 1,3-butadiene)

  and / or an acetylenic hydrocarbon (propyne, ethylacetylene and / or vinyl

acetylene).

  These cuts are subjected to the following operations: a) reacting with at least one saturated aliphatic alcohol

  1 to 4 carbon atoms, in the presence of an acid catalyst,

  removing at least 95% of the isobutene by converting it to ether and separating said ether and unreacted alcohol from the C4 fraction; b) reacting the C4 cut from step (a) with hydrogen, in the presence of a hydrogenation catalyst, in

  conditions of selective hydrogenation of acetylenic hydrocarbons

  and / or diolefinic (that is with hydrogenation as

  n-olefins) and isomerization as low as

  butene-1 (ie with a conversion of butene-1

  less than 155%, preferably less than 5%).

  c) Distillation of the product of step (b) under conditions of

  essentially ensuring the attainment of at least 96% (preferably

  at least 99%) of butene-2 and at least most of the n-

  butane in the bottom, and at least most butene-1-with

  isobutane and a minor proportion of n-butane in

  d) treating the top product of step (c) in an extraction zone, preferably extractive distillation, so as to

  to collect, in bottom, the butene-1 sought and, at the head, the hydrocarbons

  saturated bures (isobutane and optionally n-butane).

  Preferably, in step (c), at least 96% (and more preferably

  at least 99%) butene-2 and less than 20% butene-1 is collected in the bottom; and preferably at least 80% butene-1 and less

  4% (advantageously less than 1%) of butene-2 is collected in the form of

  you. By way of example, an unsaturated C4 cut, after conventional extraction of butadiene, contains in% by weight: saturated hydrocarbons (butane / or isobutane): 1 - 15% isobutene: 20 - 70% butene-1: 10 - 40% butene -2: 5 - 30% Diolefinic and acetylenic hydrocarbons: 0.1 - 5% Such a cut constitutes a filler which can be treated according to the process of the invention. Small amounts of C3- and C5 +

may be present.

  The technique of prior elimination of 1,3-butadiene is of no importance for the present process. In some cases at least part of the acetylenic hydrocarbons and other diolefins

  can be simultaneously extracted.

  The isobutene of the C4 cut is first reacted with an alcohol in the presence of an acid catalyst, for example the acid

  sulfuric acid, hydrofluoric acid, aluminum chloride or fluorine

  boron. However, the carbon-containing materials containing -SO 3 H groups, for example sulfonated carbons, for example Nalcite X or AX, Zeo-Karb-H, or sulfonated phenol-formaldehyde resins (for example Amberlite IR-100, Nalcite MX), are preferred. indene-sulphonated coumarone polymers or, preferably, polystyrene divinyl benzene resins

  sulphonated, for example Dowex 50, Nalcite HCR and Amberlyst 15.

  When operating continuously, the volume of feed treated per volume of catalyst per hour is usually from 0.5 to 20. It is usually carried out at 20 ° C. to 150 ° C., preferably 40 ° C. to 1000 ° C., with 0.9 to 10 ° C. preferably 1 to 2 moles of alcohol per mole of isobutene, a

  excess of alcohol favoring the reaction.

  Alcohol can be, for example, ethanol or preferably

methanol.

  The etherification reaction is well known and described,

  for example in US Patents 2,480,940, 3,037,052 and 3,281,475.

247402-4

  It is clear that butene-1 will be even easier to pu

  that the conversion of isobutany in the first stage will have been more extensive. We therefore preferably choose conditions ensuring

  a conversion of at least 95%, preferably at least 99% of the isobutane

  Tene. These conditions are fulfilled, for example, by the process of

  French patent application 7910399 of April 24, 1979.

  At the end of this first step, the formed ether is separated and

  the residual alcohol of unreacted C4 hydrocarbons. This separation

  can be done by any of the known techniques, for example

  for example adsorption, washing with water, distillation or combination of both.

  Distillation presents some difficulties because of the training

  azeotropes; many proposals have already been made to resolve

  to this difficulty; it will not be discussed here.

  The hydrocarbon cut, depleted in isobutene, after removal

  of ether and residual alcohol, is

  (b) selective non-isomerizing hydrogenation.

  * The selective hydrogenation of acetylenic and diolefinic hydrocarbons in the presence of mono-olefins is carried out in the presence

  a noble metal catalyst. A preferred catalyst is palladium.

  The catalyst can be used in the supported state. Examples

  Many supports are alumina, silica, spinel or coal.

  A catalyst with 0.01 to 2% by weight of palladium on alumina is preferred.

  re. The hydrogenation temperature depends on the catalyst used, it is most often between 10 and 1000.degree. C., preferably between

O and 400C.

  The reaction is carried out in the vapor phase or, preferably, in the liquid phase, in the presence of hydrogen, and the pressure may be, for example, from 1 to atmospheres, preferably from 1 to 10 atm. The hydrocarbon flow rate is, for example, from 1 to 50 volumes (liquid) per volume of catalyst per hour. For example, 1 to 2 moles of hydrogen per mole are used.

  of acetylenic or diolefinic hydrocarbon.

  After separation of the hydrogenation gas, the hydrocarbon fraction is subjected to fractionation by distillation (step c).

  carried out, preferably, by the high fractionation technique (super-

  fractionation), with one or more columns comprising in total, for example, 40 to 250 theoretical plates. The severity of splitting

  is a function of the degree of purity desired for butene-1 and butene-2.

  At the end of step (c), the hydrocarbon mixture obtained as overhead product (essentially butene-1 and at least one saturated hydrocarbon) is subjected to a liquid-liquid extraction or preferably

  extractive distillation of conventional type.

  As the polar extraction solvent, it is possible to use, for example, dimethylacetamide, dimethylformamide, furfural,

  N-methyl pyrrolidone, formylmorpholine or acetonitrile. Name-

  many other solvents are known and the invention is not limited to

  choice of specific solvents. However, dimethylacetamide is preferred

  of. At the top, the saturated hydrocarbons are collected and in the bottom a solution of butene-1 in the extraction solvent. Butene-1 can be removed by simple distillation, by stripping or by stripping with an immiscible auxiliary solvent such as

  paraffinic hydrocarbon easily separable by distillation of the

  Tene-l. The invention is illustrated by the attached figure. The C4 hydrocarbon feedstock, derived from a butadiene extraction unit, is sent via the line 1 to the reaction zone 2 fed with

  alcohol after driving 3. After splitting the products,

  the ether formed by line 4 and the residual hydrocarbons-

  5. The latter, previously freed from the residual alcohol by appropriate treatment, for example by washing with water, are treated with hydrogen, introduced via line 7, into the zone.

hydrogenation 6.

  After separation of the residual hydrogen gas, the hydrocarbons

  bins are sent via line 8 to distillation zone 9. In bottom, almost all butene-2 (at least 96%,

  preferably at least 99%) and most of the n-butane

  10. The top product (at least 50%) of the butene-1 submitted to the

  tillation, preferably at least 90%, as well as isobutane and possibly traces of other hydrocarbons) is sent via line II to the extractive distillation zone 12. At the top the paraffins are separated and at the bottom (line 14 ) a solution of butene-1 in the extraction solvent. This solution is redistilled in the column

  15. Butene-1 is collected by line 16, while soil

  extraction is returned via line 17 to zone 12.

EXAMPLE

  A cut of C4 hydrocarbons from a steam-cracking process which has been extracted from butadiene is treated. After this extraction, its composition (% by weight) is that given in Table 1, Column A. This section, added with methanol, is passed over a catalyst formed of a sulfonated ion-exchange resin based on

  polystyrene crosslinked with divinylbenzene (Amberlyst 15). The temperature

  The temperature was 50-90 ° C and the pressure was 10-20 bar. The modern report

  methanol / isobutene was 1.14. The procedure was carried out according to the technique of French patent application 9 910 399 (Example 2), comprising two reaction stages with intermediate separation of MTBE, washing

  with C4 cut water and unconverted methanol recycling.

  The overall conversion of isobutene was 99.8% and the C4 cut obtained had the composition given in Table 1, Column B.

  The C4 cut, substantially free of isobutene (

  less than 0.2% by weight) was added with hydrogen and subjected to selective hydrogenation under the following conditions: Catalyst: 0.3% by weight of palladium on alumina Conditions: temperature: 50 ° C., pressure 3 kg / cm 2; hourly flow rate of hydrocarbon liquid charge: 10. The quantity of hydrogen represents 1.2 times the quantity theoretically necessary

  to hydrogenate butadiene to butene.

  The composition of the effluent is given in Table 1, column C. After separation of the unreacted hydrogen, the hydrogenated C4 cut (butadiene less than 10 ppm by weight) was sent to a distillation unit comprising two columns. in series of 70

  trays each, with a reflux ratio of 14 compared to

  tillat. At the bottom of the 2nd column, butene-2 was collected with

almost all n-butane.

  At the head, almost all isobutane and most of 1-butene were obtained. The molar compositions of effluentsde

  Head and Bottom are given in Table I (Columns D and E).

  The top effluent from this distillation constitutes the

  distillation of an extractive distillation column of 60 trays.

  The solvent used is dimethylformamide, which is sent into the column, 8 stages from the top, with a flow equal to 4.2 times that of the feed. The vapors of the head are condensed; half of the condensate is recycled at the top of the column, as reflux, while

  that the other half of the condensate is removed from the system.

  The residue, consisting essentially of dimethylformamide and butene-1, is sent to the solvent regeneration column comprising 40 trays. The bottom effluent of this column constitutes

  the regenerated dimethylformamide and is recycled to the distillation column.

  extractive tillation, as defined previously. Head effluent

  is the purified butene-1 whose composition is given in the colon

No. F of Table I.

TABLE I

  Composi- Load Output Exit Effluent Effluent Butene-l (F) tion (% (A) step step of bottom head

  by weight) (a) (b) distilla- distilla-

(B) (C) tion (D) tion (E)

hydro-

  bures C3 0.3 0.6 0.6 1.27 Isobutane 1.2 2.2 2.2 4.66 0.06 n-butane 5.8 11, 0 12.0 1.06 21.77 0, 32 Isobutene 47.3 0.2 0.2 0.41 0.02 0.44 Butene-1 27.0 51.0 48.5 92.53 9.18 99.10 Butene-2 18.0 34.2 36.1 0.07 68.27 0.08 Butadiene 0.2 0.4 10 ppm

hydro-

bures C5 0.2 0.4 0.4 0.76 J1

Claims (9)

  1. A process for producing butene-1 from a hydrocarbon fraction   C4 bures containing at least n-butane, butene-1, butene-2,   isobutene and at least one diolefinic or acetylated hydrocarbon   wherein said slice is reacted with at least one saturated aliphatic alcohol having 1 to 4 carbon atoms per molecule, characterized in that   1) said reaction is carried out under conditions as   an isobutene conversion of at least 95%, said conversion of   the residual C4 fraction of said ether and residual alcohol is separated off, and said residual C4 fraction separated from the residual C4 fraction is reacted.   ether and alcohol, with hydrogen, in the presence of a   hydrogenation catalyst under hydrogenation conditions.   selective nation of acetylenic or diolefinic hydrocarbons.   with reduced isomerization of butene-1 to butene-2, and   re the product of the unconverted hydrogen, 3) the product of step (2), distilled from hydrogen, is distilled under conditions essentially ensuring, in the bottom,   at least 96% butene-2 and at least most of the n-   butane, and at the top, at least most butene-1 with optionally isobutane and n-butane not collected in the bottom, and 4) the top product of step (3) is treated in a solvent extraction zone and a raffinate and an extract are collected   and the extract is fractionated to separate the butene-1 from the solvent.   2. The process according to claim 1, wherein step (2) is   made with a palladium catalyst at a temperature of -10 to   + 100C and under a pressure of 1 to 30 atmospheres.   3. A process according to claim 1 or 2, wherein step (3)   is carried out in a distillation zone of equiva-   are worth 40-250 theoretical plateaus.   4. Method according to one of claims 1 to 3, wherein the step   (3) is carried out by leaving at least 99% butene-2 in the bottom and   at least 90% butene-1 at the top.   5. Method according to one of claims 1 to 4, wherein the step   (4) is carried out by extractive distillation with dimethylfor- formamide.   6. Method according to one of claims 1 to 5, wherein the cut   C4 hydrocarbons contain at least the following hydrocarbons in the following weight terms: saturated hydrocarbons (butane and optionally isobutane): 1-15% isobutene: 20-70% butene-1: 10-40% butene2: 5-30 % Diolefinic and / or acetylenic hydrocarbons: 0.1-5% 7.The method of claim 2, wherein the temperature is   from 0 to 40 C and the pressure from 1 to 10 atm.   8. The process according to claim 7, wherein from 1 to 2 is used.   moles of hydrogen per mole of acetylenic hydrocarbon or diolefin Picnic.   9.- Method according to one of claims 1 to 8, wherein the setting   in reaction with a saturated aliphatic alcohol is in   conditions ensuring isobutene conversion of at least 99%.