SK280789B6 - Method of skeleton isomerization of olefinic unsaturated compounds - Google Patents

Abstract

Disclosed is a method of skeleton isomerisation of olefinic unsaturated compounds having the number carbons in a molecule ranging from C4 to C12, which isomerisation is carried out in the presence of a heterogeneous catalyst at 300 - 600 degrees Celsius and at pressure ranging from 0.08 to 1 MPa whereto at least one unsaturated C4 to C12 compound or alcohol. Dehydrating - isomeric catalyst is based on gamma-Al2O3 that is modified under the influence of at least one aqueous solution with the concentration within the range of 0.01 to 4.8 wt.% and being selected from among H2SO4, HNO3, (NH4)2SO4, NH4HSO4, NH4NO3, which catalyst is thereafter deprived of water and fired in oxygen gas-containing atmosphere at 300 - 650 degrees Celsius. The isomerate thus obtained is recovered or subjected to further processing, and the catalyst is re-activated by oxygen-containing gas at 300 - 650 degrees Celsius at the 10 percent decrease of its activity.

Description

Technical field

The invention relates to the skeletal isomerization of olefinically unsaturated compounds, in particular olefins and cycloolefins, but also from in situ aliphatic and cycloaliphatic alcohols as their precursors, with a carbon number of 4 to 12 on a heterogeneous dehydration-isomerization catalyst.

BACKGROUND OF THE INVENTION

It is long known [Letter 1.1. et al., Kinetics i kataliz 6, 741 (1965); Macho V., Polievka M .: Petrochemistry 1965, 30; DE 3 317 165] that by dehydration of n-alkanols on γ-Al ₂ O ₃ and other acidic catalysts mainly 1-alkenes and to a lesser extent positional isomers, i.e. n-alkenes having an internal double bond position, are formed; in turn, tertiary butyl alcohol essentially produces only isobutylene and the like. Dehydration of primary alcohols on potassium phosphate impregnated with NaOH as well as on calcium phosphate at a temperature of about 400 ° C produces 1-alkenes [Frejdlin L. Ch. et al., Neftechimija 1, 749 (1961); ibid 3, 10 (1963)] as well as on 0.25 wt.% alumina impregnated. alkali metal hydroxide [Letter 1.1. et al .: Kinetics i kataliz 6, 741 (1965)] at a temperature of about 300 ° C. Even β-alcohols on thorium and lanthanum oxides at about 400 ° C produce 1-olefins [Lundlen AJ et al: J. Am. Chem. Soc. 85, 2180 (1963); Chem. Eng. News 41, 42 (1963)]. However, the skeletal isomerized alkenes, in particular the C ₄ and C ₅ alkenes, are prepared essentially only by the skeletal isomerization of n-alkenes, such as isobutylene from n-butenes and isoamylenes from n-pentenes, on strongly acidic heterogeneous catalysts, such as aluminosilicates, chlorinated and optionally brominated alumina [Rohrer JC et al .: J. Phys. Chem. 66, 1962, p. 2070; Kaiser JR et al., Ind. Eng. Chem. Prod. Res. Dev. 1, 1962, no. 2, p. 127; US 3,558,733, 3,663,453, 3,730,958, 3,751,513; Fridstejn IK et al .: Neftechimija 4, 1964, p. 681; Takeshita T et al., Catal rew. 8, 1973, p. 29; Otremba M. et al., Nephtechimija 20, 1980, p. 20]. However, there is a drawback to the need for frequent activation of such catalysts by the action of halogens, hydrogen halides or halocarbons, and contamination of products with halogen compounds with all technological and environmental consequences. In addition to acidic activation, reactivation or firing of polymers and carboids from the catalyst is also required. Similar problems or low efficacy are also encountered in the application of alumina with zirconia or admixtures. zirconium halide and silica [GB 1 065 005 and 1 065 010; US 4,038,337], n-pentenes form isoamylenes on alumina modified with silica [SU 906 360; Neftechimija 8, 1988, p. 613]. The selectivity, especially when applied to n-butenes, is lower. However, tert-olefins can also be isomerized [GB 1 065 005; US 4,499,325, 4,544,780], such as isobutylene to n-butenes on borosilicate or fluorinated alumina at a temperature of 250 to 550 ° C. But the first catalyst has low efficiency and the second one needs to be acidified frequently and contaminates the product with a fluorocarbon. Similarly, they are known [Takeshita T et al .: Catal. Rev. 8, 1973, no. 1, p. 29; Misono M et al., J. Catal. 10, 1968, p. 88; FR 1,352,299; No. 1 379 412] and the acidic properties of alkaline earth and metal sulphates as well as their use only for the positional isomerization of 1-butenes to 2-butenes and vice versa. It is probably because they were pure sulphates. Thus, [SU 1 004 332] the simultaneous dehydration of cyclohexanol associated with the subsequent skeletal isomerization of cyclohexene to methylcyclopentenes on zeolites and chlorinated alumina at 350 to 450 ° C is also known. The efficiency of the technically demanding zeolites is low and chlorinated alumina requires, in addition to reactivation, frequent acidification with halogen compounds, which additionally contaminate the product.

SUMMARY OF THE INVENTION

The present invention provides a process for the skeletal isomerization of olefinically unsaturated compounds having a carbon number of 4 to 12 on a heterogeneous dehydration-isomerization catalyst at a temperature of 300 to 600 ° C and a pressure of 0.08 to 1 MPa, which is carried out such that at least one olefinically unsaturated compound C ₄ to C ₂ and / or at least one alcohol C ₄ to _{C) 2,} dehydrating the olefinically unsaturated compound is fed to the catalyst is γ-alumina modified by treatment with at least one aqueous solution of a concentration of 0.01 to 4.8 % by weight selected from aqueous solutions of sulfuric acid, nitric acid, ammonium sulphate, ammonium hydrogen sulphate, nitric acid and ammonium nitrate, followed by dewatering and firing in the presence of an oxygen-containing gas at 300 to 650 ° C, the formed isomerisate being isolated and / or leads to further chemical uses and heterogeneous dehydrates The black isomerization catalyst is reactivated with an oxygen-containing gas at a temperature of 300 to 650 ° C after a decrease in activity of at least 10%.

Skeletal isomerization, respectively. dehydration conjugated to skeletal isomerization, preferably in the presence of at least one of nitrogen, carbon dioxide and hydrogen. Carbon dioxide is the most effective.

Furthermore, γ-Α1 ₂ Ο ₃ is particularly desirable to remove adsorbed and volatile components by heating, in particular by heating under reduced pressure, prior to impregnation with an aqueous solution. This exposes the surface of γ-Α1 ₂ Ο ₃ and releases the pores for solution penetration.

According to the invention, the olefinically unsaturated compounds C ₄ to C 12 are mainly individual olefins or mixtures of C ₄ to C ₁₂ olefins, in particular n-butenes, n-pentenes, but also double bonded terpenes per molecule, C ₆ cycloolefins, in particular cyclohexene and alkyl cyclohexenes.

Mixtures of aliphatic and cycloaliphatic alcohols may also be used as aliphatic alcohols C ₄ to C ₁₂ according to the invention, in addition hydrocarbons and other oxygenated organic compounds and water may also be present. A mixture of butanol, isobutanol, 2-ethylhexanol, 2-ethyl-4-methylpentanol together with aldehydes, ketones, ethers and esters isolated as a byproduct from propylene oxonation oxo products and higher olefins can be used as a mixture of C ₄ -C ₈ alcohols. Further, a by-product alcohol from the production of cyclohexanol and cyclohexanone by oxidation of cyclohexane, consisting mainly of n-pentanol, alcohols, C ₂ to C ₄ ketones and ethers.

Impregnation of γ-Α1 ₂ Ο ₃ is carried out with dilute aqueous solutions in the range of 0.01 to 4.8% by weight, with a concentration in the range of 0.4 to 1.5% by weight being most preferred, with sulfuric acid solutions and / or ammonium sulfate or ammonium hydrosulfate. The same is true for nitric acid and ammonium nitrate. Higher concentrations of aqueous solutions, ie above 4.8 wt.% And below 0.01 wt. is already marked by a decrease in the activity and selectivity of the dehydration-isomerization catalyst. For the firing of the catalyst as well as the reactivation of the catalyst, air containing oxygen or a mixture of air with additional nitrogen, carbon dioxide and the like can be applied as oxygen-containing gas. Pou2

Substitution of nitrogen with noble inert gases is a cost-effective option.

The advantages of the process according to the invention are technical simplicity, long lifetime of the applied catalyst, its technically and energy-saving reactivation, high purity of the products, free of foreign matter. Then the possibility to use a wide range of starting materials for targeted production of alkenes. Thus, in the case of the availability of isoalkenes or isoalkanols, these can also be used to produce n-alkenes and vice versa. If isobutylene and isoamylenes are needed and the availability of n-butenes, n-pentenes or butanol and pentanol, these can be converted into isobutylene and isoamylenes in one process step, particularly useful for the production of methyl tert-butyl ether, methyl tert-amyl ether and the like. In the case of the spraying of alcohols on the dehydration-isomerization catalyst, in situ reaction water is also used to extend the cycle time from reactivation to further reactivation of the catalyst. The process allows the flexible production of C ₄ to Cu alkenes of the desired structure on a single catalyst and apparatus depending on production and market needs.

Further advantages of the method according to the invention, as well as further data on its implementation, are evident from the examples.

DETAILED DESCRIPTION OF THE INVENTION

Example 1

Extruded γ-Α1 ₂ Ο ₃ with a diameter of 1 mm and a length of up to 4 mm, with a specific surface area of 238 m ² . g ^-1 , at a rate of 25 cm ^3, is evacuated at 300 ° C (2.7 MPa) for 3 h. Then, with continued evacuating, but at room temperature, the γ-alumina was added 400 g of an aqueous solution of ammonium sulfate (NH 4) ₂ SO ₄ at a concentration of 1% by weight. Thereafter, the aqueous solution together with the alumina were heated at 93 to 98 ° C for 4 h at atmospheric pressure. The alumina is then separated, dried in the air and fed into a stainless steel reactor, where it is heated gradually up to 450 ° C in the air stream (3 dm ³ , h ^-1 ) and finally at 500 ° C in the stream. air (3 dm ³ , h ^-1 ) for 2h.

This dehydration-isomerization catalyst is contained in a stainless steel flow reactor with an inner diameter of 30 mm and a height of 500 mm. At the bottom is a grate with a layer of Rashig rings of stainless steel with a size of 5x5 mm up to a height of 150 mm. On this layer the basalt wool is 5 mm thick and then the catalyst layer is 25 cm ³ . On the catalyst again a layer of basalt wool and finally a layer of Rashig rings up to a height of 100 mm. A 6 mm diameter thermowell is received in the center of the catalyst bed, in which a platinum thermometer sensor is received. The reactor is heated by means of an electrically heated jacket with a digital temperature controller with an accuracy of + 3 ° C. The reactor is connected to a steel condenser and a water-cooled optional liquid separator using a duplicator at a temperature of 12-16 ° C.

The residual pyrolysis fraction C ₄ (raffinate C ₄ ) is fed from a 2 dm ³ steel pressure bottle through a capillary flowmeter to the top of the reactor. Instead of raffinate C ₄ , other alkenes or alcohols, air or nitrogen may be added to the reactor. The gas enters the top of the reactor, where it is preheated to the required temperature on the Rashig ring layer, then continues through the catalyst, further Rashig rings to the condenser. There, a possible liquid fraction is collected and is collected in a separator. The gas from the separator is passed through a gas meter and a sampler or chromatograph to a degassing line. The raw material used and the reaction products are analyzed by chromatography. The catalyst is reactivated with air at 450 ° C for 2 h at 6 h intervals.

For the skeletal isomerization, the residual pyrolysis C ₄ fraction (raffinate C ₄ ) of the following composition (% by weight) is fed: methanol = 0.1; methyl tert-butyl ether = 0.1; propane = 0.2; propene = 0.2; isobutane = 7.3; n-butane = 17.2; 1-butene = 42.8; isobutylene = 3.2; trans-2-butene = 18.2; cis-2-butene = 10.5.

0.75 g is charged to the catalyst at 400 ° C. cm &^lt; ^{5 >} h &^lt; ^{-1 > of} raffinate C ₄ , then similarly sludge at 450-500 [deg.] C. Product samples analyzed after 1 hour of skeletal isomerization at 400, 450 and 500 ° C have the following composition (in% by weight): methane + inert = 0.5; 0.1; respectively. 0.4; ethane = 0.02; 0.05; respectively. 0.4; ethylene = 0.3; 0.7; respectively. 1.7; propane = 0.3; 0.7; respectively. 1.7, propane = 11.1; 11.6; respectively. 14.0; propylene = 3.0; 6.9 and 11.6, isobutane = 11.1; 11.6; respectively. 14.0; n-butane = 16.1; 17.4; respectively. 18.4; 1-butene = 13.7; 10.4; respectively. 9.2; isobutylene = 16.8; 22.9; respectively. 18.4; trans-2-butene = 20.1; 13.7; respectively. 11.2; cis-2-butene = 13.9; 9.8; respectively. 8.0; hydrocarbons C ₅ (mainly isoamylenes) = 2.5; 5.2; respectively. 4.4. The conversion of n-butenes is thus 33.3; 52.6, respectively. 60.3%. Isobutylene selectivity = 57.1; 52.4 and 35.2%, isobutylene yield (per pass) = 19.0; 27.5 and 21.2% respectively.

With a catalyst loading of 1.5 and 2.2 g.cm &^lt; ³ &^gt;. h ^-1 at 425 ° C the conversion of n-butenes reaches 45.9 and 45.9%, respectively. 44.2% selectivity to isobutylene 66.5, resp. 65.5% and isobutylene yield (calculated on n-butenes) per pass 30.5 and 30.5%, respectively. 29.0%.

Under otherwise similar conditions, but using an aqueous solution of ammonium sulphate at a concentration of 7% by weight, with the same amount of (NH ₄ ) ₂ SO ₄ , for the acidification of γ-Α1 ₂ Ο ₃ as catalyst, such a catalyst yields isobutylene yield (calculated from n-butenes) per pass by 20 to 25 rel. % lower.

Example 2

The catalyst prepared according to Example 1 is subjected to a skeletal isomerization of the residual pyrolysis C ₄ fraction (raffinate 2) specified also in Example 1. The skeletal isomerization is carried out similarly to Example 1, on the one hand using carbon dioxide or hydrogen additives in the supplied pyrolysis residue. C ₄ fraction. The effect of CO ₂ and hydrogen on skeletal isomerization at 425 ± 3 ° C and various catalyst loads, on the one hand conversion of n-butenes to one catalyst per pass, and on selectivity to isobutylene, alkenes C ₂ to C ₃ , butane with isobutane, C ₅ olefins, isobutylene yield per pass ", isoamylene yield, which of course, the yield or selectivity and the isobutylene in the feed should not be counted, i.e. at the inlet of the pyrolysis of residual C ₄ fraction. Thus, the isobutylene yield is the newly formed isobutylene, which can be expected to be fully convertible in the balance, e.g. in etherification to methyl tert-butyl ether. In addition, whether for the use of such an isoerisate for the production of methyl-tert. butylether or alkylbenzene can also be expected to yield isoamylenes which, in etherification with methanol, give tert-amyl methyl ether.

At 6 h intervals, the catalyst was reactivated with air for 1.5 h at 425-450 ° C.

The most important reaction conditions and results are summarized in Table 1.

The results reveal the positive effect of the addition of carbon dioxide and partly hydrogen, in particular on the selectivity of the skeletal isomerization.

SK 280789 Β6 íčSuika i

I- * * á ABOUT Chrc «atO £ raricl <4 anyýja proCuktu [x hral.j s .5 WITH and tT 4 Ž j FROM 1 425 0.5 0.21 0.08 0.50 1.51 0.15 4.36 11.91 16.29 13.68 - 4.5 425 0.5 00:23 0.05 0.45 1.25 0.10 8.85 11:43 15, M 11.83 - 1 425 G.5 00:25 0.02 00:50 0.31 0.28 5.18 10.36 19.33 13,2c .- 7 425 0.5 C, 23 st. 0.?5 0.10 0.42 2.51 8.46 19,00 12.56 °> Ζ 4 4.5 425 0.5 0.3 sl. 0.3 0.2 0.7 2.5 9.1 17.8 13.2 "i ABOUT 1 425 0.5 0.2 0.02 0.5 o.t 2.1 3.5 e, s 18.3 1'3 "i 6 3 425 0.5 0.2 0.0? 0.4 0.2 3, II 2.9 9.1 17.3 12.2 ^tC Z 6 about 425 0.5 0.2 st. 0.4 0.3 2.59 2.4 9.1 15.7 13.7 "i 12 T 425 Delta, 5 0.2 st. 0.4 0.3 73 3.2 8.7 16.9 n J ^ct 7 12 1.5 425 o.5 0.3 st. 0.4 0.3 6.21 2.7 8.8 16.9 12.3 ^and ! 12 4.5 425 0.5 0.2 st. 3.4 0.3 5.68 2.4 9.1 16.4 13.1 ^tt Z 12 7 425 0.5 0.2 0.02 0.4 0.1 4.5 2.3 73 H.5 13.0 - 1 425 0.15 0.1 0.03 0.3 0.4 0 5.9 10.2 193 9.4 - - 7 425 0.35 0.3 st. 0.5 0.1 0.4 3.7 9.9 13.6 11.6 - 1 <25 0.35 0.3 st. of 5 03 - 5.5 H.3 17.4 10.2 - - 7 425 00:35 0.2 By $ 1. 0.3 0.1 ’ 0.6 3.2 73 20.4 10.6; s 4 2 425 0.35 0.2 0.02 0.5 0.4 0.3 4.3 10.4 10.1 IC, 6 and 4 7 425 00:35 0.1 0.03 0.5 0.3 0 43 10.1 18.7 11.2 s 6 4 425 J.5 0.3 0.02 0.3 0.7 0.2 33 10.1 17.4 113 h 6 δ 425 of 5 0.2 0.03 0.4 0.7 0.5 3.2 10.2 17.0 12.4 ^H 2 5 2 <25 0.35 0.2 0.03 0.5 0.7 0.2 4.3 10.8 16.8 10.4 ^H z g about 425 3.35 0? 0.72 0.5 0.6 0.5 3.8 10.7 17.4 11.1 from 12 2 425 0.35 0.1 about.:? 0.4 0.6 st. 4.1 11.3 19.2 10.3 from 18 7 425 00:35 about.? 0.02 0.5 0.4 0.3 3.3 10.0 173 H.7

Table 1 - continued

Chromatographic analysis of the product Γχ iwot.j total leakage (X hsot.J .S ij 1 £ í Ύ s 4 s B and F F 5 7 T 7 F S í í 8 J 20.99 16.17 11:47 0.2 0.2 1.1 0.8 0.4 2.5 1.3 3.7 73.6 t «, 81 18.01 12.54 0.1 0.2 0.8 0.4 0.3 1.8 0.9 2.7 75.9 23.16 14.87 10.41 0.3 0.3 1.6 1.9 0.4 3.3 i ,? 5.1 74.7 19.75 18.63 13,11 0.2 3.2 1.0 0.9 0.3 0.2 1.4 1.4 50.7 13.8 19.4 > 3.7 OH in 0.1 0.9 0.6 0.2 1.9 0.9 2.9 75.2 21.6 16.8 12.2 0.1 0.2 0.9 C, d 0.3 2.7 1.0 3.7 78.6 19.7 13.2 U of 0.1 0.2 0.8 What 0.2 1.7 0.9 ?. 1 74.1 16.5 23.5 14.5 0.8 0.1 0.7 0.4 0.2 0.7 2.2 75.3 19.7 15.5 11.8 0.2 0.2 0.9 0.6 0.3 1.8 1.1 2.9 72.9 16.5 17.6 1? 4 0.1 0.1 0.7 0.4 0.2 1.5 0.7 2.2 74.8 16.1 13.4 13.7 0.1 0.1 0.7 0.5 0.2 1.5 0.8 2.3 73.8 17.4 13.7 14.2 0.1 0.1 0.6 0.4 0.2 1.3 0.7 ?,about 72.9 23.9 14.1 93 0.2 0.3 1.3 1.0 0.4 2.6 1.6 4.1 72.1 22.1 17.1 12.1 0.2 0.2 t.o 0.5 0.3 2.3 1.3 3.5 73.2 24.0 14.5. 10.3 J 2 0.2 1.1 0.7 0.4 2.3 1.3 3.6 73.1 23.4 15.5 11.3 0.3 0.3 1.3 0.8 0.4 2.7 1.5 -.3 73.0 23.1 15.8 11.1 0.3 L, 4 2.0 1.4 0.7 0.5 2.5 2, i 53.0 23.3 16.3 11.3 J 2 J 3 1.0 0.6 0.3 2.0 1.1 1.4 56.3 20.0 18.1 13.2 0.2 0.2 1 ' 0.9 0.2 2.4 1.3 3.6 74.3 19.6 18.6 13.4 0.1 0.1 0.8 0.6 0.2 1.9 ž, 9 2.7 74.5 23.2 16.1 11.4 0.2 0.3 ', 2 0.1 0.4 2.5 1.4 3.- 7? 9 22.0 16.3 11.8 0.1 0.2 1 of 0.7 0.4 2.1 I.3 J.3 71.2 22.1 16.2 11.4 j 0.2 0.2 1.1 0.0 3.3 2, í '4 J, 7 72.9 21.5 7.6 12.4 0.1 0.2 -72 _: • J b 0.3 2.0 M - ·> OJ

Table 1 - continued

J 3 w. . L · » u se Selective n-butenes r: f XJ C • S M O> i? >  5 U 3 5? > N and cT ω ⁴ c " 3 ♦ <_r 46.4 53.6 0.6 19.5 10.4 15.3 24.9 5.2 40.7 57.1 0.0 17.7 11.7 12.4 23.2 3.3 59.3 55.5 0.7 6.15 11.1 19.1 27.9 7.2 33.0 60.9 1, "J 0.7 9.9 17.2 23.1 3.3 34.9 63.1 1.2 10.1 9.4 15.4 22.0 4.0 42.5 82.1 0.9 12.3 those d 15.9 26.4 5.3 37.5 63.9 1.0 11.2 9.2 13.3 23.9 3.3 29.9 64.3 I, U 12 G 8.2 14.1 19.2 3.2 40.6 62.0 0.9 12.3 9.6 14.6 25.1 4.4 35.9 62.6 '.i 11.8 10.3 1, those 23.1 2.2 31.5 61.6 0.9 12.2 10.1 14.6 19.4 3Λ 31.3 67.3 1.2 11.2 7.7 12.6 21.1 2.9 53.4 54.2 0.3 16.1 11.6 15.7 29.0 6.0 43.0 61.6 0.8 12.4 U, 8 14.4 25.5 4.3 51.0 56.8 0.8 17.5 »1.0 13.5 29.0 5, the 47.5 59.6 o, 7 9.0 10.2 Π 2 26,3 6.0 47.6 53.4 0.5 14.3 10.9 15.3 27.8 4.0 45.7 61.5 0.3 13.2 12.3 ' 12.9 28.1 3.3 39.8 59.2 1.0 12.4 9.4 17.2 23.6 5.1 37.8 60.6 0.8 14.1 U-6 13.6 22.9 3.3 47 u 53.4 0.7 14.9 8.4 '15 8 27.9 5.4 44.5 5'3,1 0.6 15.4 10.5 14.4 26,3 4.6 46.9 56.5 0.4 14.0 13.9 15.1 26.5 5.2 41.7 61.6 .3,4 »3.7 10,0 13.7 25.7 4.6

Example 3

Using the γ-AljOj as described in Example 1, 3 catalysts were used. Catalyst A prepared by acidification of 50 cm ^{3 of} γ-Α1 ₂ Ο ₃ with sulfuric acid at a concentration of 5% by weight, Catalyst B by acidification of an aqueous solution of sulfuric acid at a concentration of 1% by weight. and Catalyst C by acidification with an aqueous ammonium nitrate solution of 1 wt.

In the preparation of Catalyst A, 50 cm ^{3 of} γ-Α 12 ₂ Ο ₃ were heated for 2 h in 100 g of a 5% by weight aqueous solution of H ₂ SO ₄ . After the acid has been separated off, the catalyst is washed three times with 25 cm @ ^{3 of} distilled water and dried at room temperature. The reactor was heated in an air stream to 500 ° C and held at this temperature for 1 h.

Catalyst B was prepared similarly to Catalyst A, but instead of an aqueous solution of H ₂ SO ₄ at a concentration of 5 wt. 1% by weight aqueous solution was used.

Catalyst C was prepared from 50 cm ^{3 of} γ- ₁₂ Ο ₃ , which was first evacuated for 3 h at a pressure of 2.67 kPa and a temperature of 300 ° C. Thereafter, it was cooled to room temperature under vacuum of γ-Α ₁₂ Ο ₃ , and 400 g of a 1 wt.% NH ₄ NO ₃ aqueous solution were also added under vacuum. and held at reflux at 100 ° C for 4 h with gentle stirring. Then the solution was decanted and the prepared catalyst was dried at room temperature and then gradually heated in the reactor to 500 ° C in a stream of air and left under these conditions for 1 h.

The individual catalysts were subjected to a ₄ -year isomerization of the n-butenes of the residual pyrolysis C ₄ fraction. One sample was investigated on catalysts A and B and the other sample on catalyst C was as follows: n-butane = 17.8; respectively. 17.3; isobutane = 6.6; respectively. 7.4; 1-butene = 50.1; respectively. 42.8; trans-2-butene = 14.1; respectively. 18.2; cis-2-butene = 8.1; respectively. 10.5; isobutylene = 2.3; respectively. 3.2; pentenes = 0; respectively. 0; propane = 0.3; respectively. 0.3; propene = 0.2; respectively. 0.3, with neither ethane nor ethylene present in both samples.

The reaction conditions and the results obtained are shown in Table 2. The results show a significantly higher activity of catalysts B and C compared to A, as well as the higher selectivity of the skeletal isomerization of n-butenes to isobutylene.

Reactivation of the catalyst is carried out at 430 to 480 ° C at 6 h intervals for 1.5 h with air at a flow rate of 240 cm ³ . cm ' ³ _cat h' ¹ .

Example 4

Extruded γ-Α1 ₂ Ο ₃ with a diameter of 1 mm and a length of 3 to 5 mm in an amount of 50 cm ³ at 300 ° C was evacuated to a pressure of 2.67 kPa for 3 h. then cooled to room temperature under vacuum, 400 g of a 1% w / w aqueous solution of ammonium sulfate was added. and heated to 100 ° C under reflux for 6 h. Then the prepared catalyst was decanted, dried at room temperature and then in the reactor, as described in Example 1, calcined in a stream of air at 500 ° C for 1 h (Catalyst D).

Catalyst E was prepared similarly to Catalyst B in Example 1 except that it was evacuated (300 psi) at 300 ° C for 3 h prior to acidification and then acidified with an aqueous solution of 0.5 wt.% Sulfuric acid. at 100 ° C for 1 h.

k j ä I / I ARE YOU ruk & wj n «i H Sl.kíiwl to [Z] -i 4 C F 4 I 4 4 1 FROM Í h 4 5 • c 5 and J5 à to Š J- í i I 435 O.5 0.8 M 1Í.C 5.5 lt, l 213 '5.5 J 273 43.1 II.S 1 «3 ') 3 * <55 1. » o.l 0, f 1.2 ».T D.3 > 3.2 13.0 17.1 12.3 2.9 41.1 92.1 1 i 2 15.0 23 21.7 495 ^{', J} 4.4 M.4 16.7 9.7 19.0 13 23 31.4 32.6 76.2 25.2 12.6 10.2 445 1. » o.l 0.4 0.6 t. J 0.4 17.3 14.6 15.8 '9.3 14.0 2.7 333 59.4 16.1 11.2 10,0 20.1 B 448 0.5 0.1 0.4 03 3.0 3.7 19.8 133 ".1 10.2 D, and 23 37.7 573 12.7 '4.5 i: e 21.9 480 3.5 0.4 0.1 0.4 5.4 3.5 ».1 Ί,; · 13 « '3.6 14.2 4.0 50 s 48.0 '3.7 0.2 11-one 24.3; 5Λ ô.ô 0.0 1, J i-j 0.4 11.1 '7.1 13.1 n.3 2R 44.2 42.1 n, 5 24.4 1.5 450 <-. 5 0.8 3 1.2 5.4 12.1 17.0 1 in t 13.2 13.7 53 5.2 52.7 53.1 21.5 1t, S 12.8 2J, G UJ ^J · ' J.J. «5 '· * i ».e U 5 U.) 15.7 10.9 4.9 48.7 57.6 15 « 10.5 14.1 28.1 ^L 4JU CL7 -.1 U.4 1.4 *. · 17.1 16.st 11.4 21.4 16.) 11.5 3.9 44.6 57.1 18.1 12.4 0 0 » 0.8 nes 11.0 3.17 U, i 23.3 15.4 1J3 4.7 <7.7 «3 173 10.2 3.5 29.8 ’L’ 0.5 4.5 4.0 15.3 1 ?. ' 12.1 n, i '·.> n. » 43 44.4 B. L. «3 J.1 273 0.5 0 0.4 1.1 4.4 ii »3 1 »3 12.5 11.1 ₍ 4 » 473 «» 1 »3 of 2 33 23.0

Catalyst F, prepared from γ-Α ₁₂ O ₃ , characterized in Example 1, as follows: 25 cm ³ (15.2 g) γ-Ι ₂ Ο ₃ was evacuated at 0.5 kPa for 3 h at 300 + 10 ° C. Then it cooled to room temperature and added with 50 g of an aqueous solution of H ₂ SO ₄ at a concentration of 5% by weight. and kept at 100 ° C for 4 h under a steamer. It was then washed three times with distilled water, dried, evacuated again at 300 ° C for 3 hours, cooled and 0.15 g of silicone oil MF in 20 cm ^{3 of} toluene was added. Thereafter, the toluene was evaporated and the catalyst was heated in a stream of air at 500 ° C for 2 h.

The reaction conditions of dehydration of n-butanol as well as of tert-butyl alcohol with conjugated skeletal isomerization of the primary formed n-butenes, respectively. The conversion of n-butanol and tert-butyl alcohol was always complete. From n-butanol by dehydration, primary 1-butene is formed, its 2-butenes (cis- and trans-) positional isomerization and isobutylene by skeletal isomerization. The tert-butyl alcohol primarily results in isobutylene and its skeletal isomerization of 2-butenes and further their positional isomerization of 1-butene.

We can see that isobutylene is also produced from n-butanol and not only isobutylene from t-butyl alcohol, but also 2-butenes, but even 1-butene.

Example 5

Catalyst E, the preparation of which is given in Example 4, performs dehydration of n-dodecanol with conjugated isomerization to skeletal isomerization of decenes to methylnonenes and other branched chain _C12 alkenes in one process stage. The catalyst loading with decanol is 0.52 g. cm ' ³ . h ^-1 at 462 + 3 ° C. Dodecanol conversion reached 100% and selectivity to methylenedecenes and dimethyldecenes 63.3%. The remainder are linear C ₁₂ alkenes and lower hydrocarbons.

Under otherwise similar conditions, 1-dodecene is fed to the scaffold isomerization with a catalyst load of 0.53 g instead of dodecanol. cm ' ³ . h ^-1 at 462 + 3 ° C. The conversion of 1-dodecene is 57% and the selectivity to methylundecenes and dimethyldecenes is 72.3%.

The catalyst is reactivated with 91% v / v mixture at 450 to 460 ° C at 8 h intervals for 2 h. nitrogen and 9% oxygen.

Example 6

Catalyst E, prepared as described in Example 4, was sprayed at 425 + 3 ° C with varying amounts of cyclohexanol at a simultaneous flow rate of 60 cm ^{3 of} nitrogen. cm ' ³ . h ' ¹ . Additional reaction conditions and results are summarized in Table 4.

Example 7

For catalyst D, prepared as described in Example 4, 0.49 g of catalyst was continuously charged with cyclohexanol. cm ' ³ . h ¹ in a stream of inert gas - nitrogen of 60 cm ³ . cm ' ³ . h ^-1 investigates the effect of dehydration temperature with conjugated skeletal isomerization. Further data and results are given in Table 5.

T * uTkt4

Ualaia keájátan rpt) SM «Ά» Η · IN M' ejkk- HH ·· herin 1 ejkto · h **> 2 - »· cyktopMta 1—1 * · cjUeM · I l-OM) 4cyUtP-M i eioyl eytío- oytte- £ OJI 00:54 00:51 0.73 • M 91.2 99.1 91.4 99.9 • M • 0.1 75.9 «Μ 21.1 19.1 24.1 »3 4 »9 4M <2.7 JM 11.7 16.5 M 11.7 11.0 5. » 6.7 03 0.6 95.7 • 9.4 79.1 4M 61.7 6.7 563 13.1 21.7 153 9.7 M M M o.i «Μ 943 • M tu 91.7

Τ * υΠα5

TeplMfl SMV MvXm curling (q crktohooNd · eykto- Bomi cjkb- Hoá l-wql · eytiopeatta 2-M · pMta l-M) * · n * kpcMte I qUopM * 2-9-8 - á- 3-Mtyl · qtiopáa FROM MO 370 41 » 455 «95 91.6 913 99.7 9 ».l 99.1 »». » «Α 24.« 59.0 153 • M 41.0 19.4 14.2 M 31.9 54.7 59.0 27.2 M 1.9 I5, J 15.3 0.0 0.7 M 33 M 91.4 • 9.7 ? ύ M.9 U 41. » 653 <7 V f, 2.0 IM im 11.9 IN 0.0 M U M 2.4 12 KU 7 »1 77.4 »13 • 9.0 42.7

SK 280789-6

Example 8

The dehydration-isomerization catalyst D specified in Example 4 was fed with n-pentanol vapors in an amount of 0.9 g. cm ' ³ . h ^-1 while maintaining the catalyst bed temperature at 450 + 3 ° C. The conversion of n-pentanol is complete, the selectivity to isoamylenes reaches 39%.

But under otherwise similar conditions, but by replacing nitrogen with carbon dioxide, the conversion of n-pentanol is also complete, but the selectivity to isoamylenes is 51.3%.

Example 9

Extruded γ-Α1 ₂ Ο ₃ with a diameter of 1 mm and a length of 2 mm with a specific surface area of 248 m ² . g ¹ in an amount of 50 cm ³ is heated to 390-400 ° C for 5 h under reduced pressure (2.67 kPa). Then also under vacuum, cooled to room temperature and quenched with an aqueous solution in an amount of 500 g of a 0.4 wt.% Nitric acid mixture. and ammonium hydrosulfate at a concentration of 0.35 wt. Then, at atmospheric pressure, the mixture is refluxed at 100 ° C for 4 h. The modifying γ-Α 12 _{1 3 is then} decanted, dried and then placed in an amount of 25 cm ³ in the reactor described in Example 1. In a stream of air for 3 h, it is fired at 500 ° C for 2 h. The air is then purged with nitrogen from the reactor and fed at a reactor temperature of 430 + 3 ° C to a catalyst under a load of 0.55 g. cm ³ , h ^-1 mixture of isoamylenes. at a conversion of 62.3, the selectivity to n-pentenes is 28.3%.

Industrial usability

The process is suitable for the skeletal isomerization of n-alkenes to isoalkenes or vice versa, isoalkenes to n-alkenes, in particular for skeletal isomerization of n-butenes to isobutylene and n-pentenes to isoamylenes, which are suitable raw materials for the production of methyl tert-butyl ether or alkyl. tert-butyl ethers, tert-amyl alkyl ethers, as high-octane gasoline additives. Isoolefins are also suitable monomers and comonomers, the production of which can be produced not only from alkenes but also from alcohols in one process step.

Claims (5)

A process for the skeletal isomerization of olefinically unsaturated compounds having a carbon number of 4 to 12 on a heterogeneous dehydration-isomerization catalyst at a temperature of 300 to 600 ° C and a pressure of 0.08 to 1 MPa, characterized in that at least one olefinically unsaturated compound C ₄ to C ₁₂ and / or at least one alcohol C ₄ to _{C] 2,} dehydrating the olefinically unsaturated compound is fed to the catalyst is γ-alumina modified by treatment with at least one aqueous solution of a concentration of 0.01 to 4.8% by weight. , selected from aqueous solutions of sulfuric acid, nitric acid, ammonium sulphate, ammonium hydrogen sulphate, nitric acid and ammonium nitrate, followed by dewatering and firing in the presence of an oxygen-containing gas at 300 to 650 ° C, the formed isomerisate being isolated and / or is led to further chemical use and a heterogeneous dehydration-isomerization catalyst is reactivated by an oxygen-containing gas at a temperature of 300 to 650 ° C after a decrease in activity of at least 10%. The scaffold isomerization process according to claim 1, wherein the scaffold isomerization is additionally carried out in the presence of at least one of nitrogen, carbon dioxide and hydrogen, Skeletal isomerization process according to claims 1 to 3, characterized in that the γ-alumina is freed from the adsorbed and volatile components by heating, preferably under reduced pressure, prior to impregnation with an aqueous solution. A scaffold isomerization process according to claims 1 to 4 3, characterized in that the olefinically unsaturated C ₄ to C ₁₂ compounds are individually or mixtures of C ₄ to C ₁₂ olefins, preferably n-butenes and n-pentenes, cycloolefins, preferably cyclohexene, alkylcycloolefins, preferably methylcyclohexenes. A skeletal isomerization process according to claim 1 4, characterized in that the alcohols C ₄ C ₁₂ represents individual aliphatic alcohols or mixtures of aliphatic alcohols, preferably n-butanol, n-pentanol and / or cycloaliphatic and alkylcycloaliphatic alcohols, preferably cyclohexanol.