Process for the hydration of mixed butenes to produce mixed alcohols

Abstract

Mixed butenes from a cracking process, or raffmates of MTBE or tert-butyl alcohol (TBA), are simultaneously hydrated using water in the presence of a catalyst to produce sec-butyl alcohol (SBA) and tert-butyl alcohol as the principal products, the mixed butanols having utility as fuel additives, e.g., as oxygenates and octane enhancers to replace MTBE, and as a neat fuel.

Claims

1. A process for the production of mixed alcohols from a liquid feedstream of mixed butenes, said mixed butenes consisting of 1-butene, 2-cis butene, 2-transbutene and isobutene, wherein a majority of the butene in said feedstream of mixed butenes is 2-trans-butene, comprising: a. providing a fixed bed reactor containing an acid hydration catalyst and a phase transfer agent; b. introducing the liquid mixed butene feedstream and water into the fixed bed reactor and into contact with the hydration catalyst under conditions favorable to hydration of the mixed butenes, to form mixed butanols, said mixed butanols comprising a majority of 2-butanol and t-butanol; c. recovering unreacted mixed butenes enriched with mixed butanols from the fixed bed reactor; d. separating the mixed butanols from the mixed butenes to forma mixed butanol product stream and a lean mixed butene stream; e. recovering the mixed butanol product stream; and f. returning the lean mixed butene stream to the fixed bed reactor.

2. The process of claim 1, where the fixed bed catalyst is in a downflow, upflow or counter-current flow reactor.

3. The method of claim 1, wherein said acid hydration catalyst is a water soluble acid.

4. The method of claim 3, wherein said organic acid catalyst is selected from the group consisting of acetic acid, tosylate acid, and perflourinated acetic acid.

5. The method of claim 3, wherein the water soluble acid is selected from the group consisting of HCl, H.sub.3PO.sub.4, H.sub.2SO.sub.4 and a heterotopoly acid.

6. The method of claim 1, wherein said acidic catalyst is a solid acid selected from the group consisting of an ionic exchange resin, an acidic zeolite, and a metal oxide.

7. The process of claim 1, wherein said phase transfer agent is Pr.sub.4NBr.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) FIG. 1 depicts an apparatus which can be used in the practice of the invention.

DETAILED DESCRIPTION OF THE INVENTION

(2) The process of the invention will be further described with reference to the attached schematic drawing. The temperature of the water and mixed butene (C.sub.4) feed streams are controlled by heat exchangers prior to their introduction into the hydration reaction 10 that also contains the acid catalyst and water at predetermined concentrations. Exemplary reaction conditions are about 150 C. and 68 bar. As shown, water is also added to the mixed butenes before their introduction into the hydration reactor.

(3) The reaction products are withdrawn from the reactor and passed through a heat exchanger to adjust the temperature of the product stream prior to introducing it into the flash drum decanter 11, which is maintained at exemplary operating conditions of 100 C. and a pressure of about 30 bar. The hydrated reaction product stream is then introduced into a recovery column 12 for release of lighter constituents from the top of the column and recovery of the butanol products as the bottoms. The column is preferably operated at, e.g., about 75 C. and a pressure of about 9 bar.

(4) The lighter constituents are subjected to heat exchange before being introduced into the accumulator decanter 13. The output of the accumulator decanter is divided into a purge mixture and a recycle stream that is returned to the hydration reactor.

(5) It will be understood that the arrangement of the apparatus and the indicated operating conditions are those presently preferred, and that other processes and systems can be employed to achieve comparable results. It will also be understood that the presence of other constituents in the feedstream, such as C3 and C5 olefins, can be tolerated, but that minor modifications in operating conditions and arrangements of the apparatus may be required. Such modifications and variations will become apparent to those of ordinary skill in the art from the present description.

EXAMPLES

(6) The following examples are given for the purpose of illustrating the process of this invention. However, it is to be understood that these examples are merely illustrative in nature, and that the present process is not limited thereto.

(7) All of the butanols utilized in the following examples were purchased directly from commercial suppliers of fine chemicals and used without any purification as GC standards. All of the pure butenes were also purchased from commercial suppliers and used without purification. All of the acids, ionic exchange resins, phase transfer agents and ionic liquids were similarly purchased. Zeolites were synthesized according to published methods. The mixed butenes were obtained from a refinery and contained no additives. The composition of the mixed butenes was determined by GC-MS as detailed below and the concentrations were determined by the method described prior to Table 1.

(8) Butene Identification and Quantification

(9) Butene identification and quantification was carried out using a commercially available gas chromatograph equipped with a flame ionization detector (FID) and a split/splitless injector. A 250 L gas sample was injected in the splitless mode. Semi-quantitative results were obtained by normalization of the peak area to the full chromatogram. All samples are analyzed in triplicate and an average value was reported.

(10) TABLE-US-00001 TABLE 1 Contents of the mixed butenes (wt %) C4 = C3 = C3 (total) 2-t-C4 = 1-C4 = 2-c-C4 = i-C4 = i-C4 n-C4 i-C5 n-C5 16.32 4.22 48.58 24.39 4.61 14.64 4.94 22.00 7.48 1.21 0.19
Butanol Quantification

(11) Hydration products were quantified using a method that is described below and the same gas chromatograph described previously, equipped with an autosampler.

(12) Butene Hydration Examples

(13) Deionized water (200 g), acid (4 g) as shown in Table 2, and optionally, a phase transfer agent, i.e., Pr4NBr (4 g) were all placed in a Parr autoclave. The autoclave was sealed and purged five times with nitrogen at 50 psi. Next, 10 mL of pure 2-trans-butene or 15 mL of mixed butenes from a local refinery were charged to the autoclave under 50 psi of nitrogen gas. The molar ratio of water-to-butenes and the mole ratio of butenes-to-acid are set forth in Tables 2 and 3. The autoclave was heated and maintained at a predetermined temperature for a period of 2-3 hours. At the end of this time, heating was discontinued and the autoclave was allowed to return to room temperature over a period of 2-3 hours before the excess pressure was vented. The autoclave was then opened and the reaction mixture was recovered. The conversion rates were determined by means of gas chromatography. The conversion rates for different hydration conditions are also provided in Tables 2 and 3, with a 100% selectivity to butanols unless other cited.

(14) The 2-trans-butene used in the tests that provided the data reported in Table 2 was purchased from a local commercial source and subjected to the indicated hydration conditions without purification.

(15) TABLE-US-00002 TABLE 2 Hydration conditions and conversion yield of 2-trans-butene* Exp. Temp Psure Time H2O/ C4/ No. Catalyst ( C.) (psi) (Hr) C4 Acid Conv % 1 ZSM5 activated 150 170 2 2.6 0.21 at 350 C. under vacuum 2 ZSm5 activated 150 240 2 2.1 0.35 at 500 C. 3 WO3/Silica 200 360 2 21 104 0.2 4 H3PO4 150 480 3 10 34 0.5 5 H2SO4 150 178 2 78 5 4.3 6 Amberlite 15/ 150 160 2 104 6 H3PO4 (2 g) 7 Amberlite 15 150 160 2 104 5.4 8 MoO3 on silica 200 160 2 104 16 4.1 9 WO3/Silica 120 150 5.5 104 38 0.1 10 WO3/Silica 200 220 3 104 41 0.64 11 H3PO4 150 160 3 104 6 0.52 12 AcOH (2.6 g) 150 250 3 52 1.6 0.23 13 AcOH (4 g)/Pr4NBr 150 160 6 104 1.6 28.6 (4 g) 14 AcOH (2)/Pr4NBr 150 180 3 104 3.2 17.5 (20 g)

(16) The mixed butene feeds used in the tests reported in Table 3 were obtained from a local refinery and subjected to the indicated hydration conditions without purification.

(17) TABLE-US-00003 TABLE 3 Hydration conditions and conversion rates of the mixed butene feeds. Reaction Conditions Based on ASD Data Exp. Reactants temp time 2-OH t-OH No. Catalyst (C) P (psi) (H) H2O/C4 C4/Acid Conv % 2-OH/t-OH Conv % Conv % 1 ZSM5 activated at 500 C 24 h and grinded 150 200 3 138 14.2 3.1 12 34 2 ZSM5 activated at 500 C 24 h and grinded 150 200 5 138 6 0.2 1.3 48 3 Dowex 50WX8 hydrogen form 150 200 3 145 10.2 2.4 8 30 4 Dowex 50WX8 hydrogen form 150 540 24 23 11.1 4.1 10 21 5 Dowex 50WX8 hydrogen form 150 200 5 138 13.4 2 10 44 6 Dowex 50WX8 hydrogen form 120 200 5 138 11.9 1.8 8.5 42 7 Dowex 50WX8 hydrogen form re-use 120 200 5 138 16.6 2.8 13.6 43 8 Amberlite CG-120-II 120 160 3 138 6.8 0.8 3.4 36 9 Amberlite CG-120-II 100 160 8 138 6.3 0.5 2.5 41 10 Amberlite 15 50 g 150 570 3 4 1.9 1.7 1.3 7 11 Amberlite 15 150 200 3 138 9.9 2.5 7.9 28 12 trifluoroacetic acid 150 200 5 138 9 13.7 2.1 10.3 43 13 H3[P(W3O10)4]H2O 150 200 3 138 115 9.8 1.1 5.7 46 14 H3[P(W3O10)4]H2O 150 200 5 138 115 8.7 1.2 5.2 39 15 H3[P(W3O10)4]H2O 150 570 3 4 74 9.6 2.3 7.5 28 16 Tungstosilicic acid hydrate 150 200 3 138 55 6.4 1 3.5 32 17 carbon black 10 g/H3PO4 2 g 150 200 4 138 115 2.9 1.8 2.1 10 18 carbon black 10 g/H3PO4 6 g 150 200 4 138 115 6.4 0.9 3.3 34 19 clay 10 g/H3PO4 6 g 150 200 5 138 115 5.6 0.5 2.1 37

(18) A gasoline with 45% light straight run naphtha (LSRN) and 55% reformate was used as a standard to test the behaviors of butanols at the same additive volume (15%). The ASTM tests methods used for the fuel tests are identified in Table 4, where MON is motor octane number and RON is research octane number.

(19) TABLE-US-00004 TABLE 4 Test methods Test method physical property ASTM D-2699 RON ASTM D-2700 MON ATSM D-323 (gasoline) RVP ATSM D-5191 (diesel) ASTM D 4052 ASTM D 5291 Specific Gravity ASTM D 4840(diesel) BTU (Heat of Combustion) ASTM D 4809 (gasoline)

(20) The ratios of components and the test results are set forth in Table 5.

(21) The examples demonstrate that butanol can be blended into gasoline as a substitute for MTBE. The petro-butanol (2-butanol/t-butanol) blended gasoline had a BTU value that was similar to MTBE blended gasoline. Although the RVP and RON values are slightly lower, they are sufficient to allow the use of the product as oxygenate and octane enhancers to replace MTBE.

(22) TABLE-US-00005 TABLE 5 Butanol effects on gasoline RVP BTU Gasoline Tests (psi) (MJ/L) MON RON 1 45% LSRN/55% 7.05 16970 81.4 87.7 reformate 2 MTBE 15% 7.41 16280 85.1 92.7 3 2-butanol/t-butanol 6.98 17514 83.2 91 (1:1) 15%

(23) Although various embodiments of the invention have been described above and in the attached drawing, other modifications and variations will be apparent to those of ordinary skill in the art from this description, and the scope of the invention is to be determined by the claims that follow.