JPH0351693B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process for the hydration of propylene to isopropyl alcohol over a solid superacid catalyst. The hydration of propylene to isopropyl alcohol in sulfuric acid solution by a two-step esterification-hydrolysis process was one of the first petrochemical processing methods dating back to the early 1920's. However, the two-step process in the liquid phase has some serious drawbacks, for example the 85% sulfuric acid required for the propylene esterification reaction is corrosive; it accelerates the hydrolysis and separates the sulfuric acid from the alcohol after hydrolysis. There is a need to dilute the acidic reaction medium to facilitate the process; there is a need to reconcentrate the sulfuric acid before recycling it to the esterification step of the process; there is often a need to neutralize the alcohol product. There is a need to do so. Direct hydration of propylene over solid catalysts is therefore a practical method to overcome the above-mentioned difficulties. Considerable research has therefore been devoted to developing methods for hydrating propylene without sulfuric acid or other liquid acids. Conventional processes that have been investigated generally involve contacting propylene with water in the presence of a suitable solid catalyst at elevated temperature and pressure to directly produce the desired isopropyl alcohol. High pressure, relatively low temperature and high steam/propylene ratio favor conversion to isopropyl alcohol. When the hydration catalyst is active at low temperatures, the reaction is usually carried out in the presence of a large excess of liquid water (ie under correspondingly high pressure). Kaiser using a sulfonated styrene divinylbenzene ion exchange resin (e.g. Amberlite 15 or IR-120 from Rohm & Haas),
Beuther, Moore and Odioso (Ind.Eng.
Chemistry Product Res. & Development Volume 1
296-302 (1962)) studies the effects of temperature, pressure, space velocity and feed composition on conversion and selectivity. The catalyst used was at low temperature (<150℃)
When not active, use gas phase operation to avoid excessive pressure. The thermodynamic equilibrium that exists at higher temperatures limits the conversion of propylene to a very low degree. Some of the reported hydration processes, essentially gas phase processes for propylene conversion, use supported mineral acids at relatively low pressures. The catalyst used was silicophosphoric acid (U.S. Patent No.
2876266), phosphoric acid of Celite (U.S. Patent No.
2579601) and tungstic acid on alumina (FJ Sanders & BFDodge, Ind, Eng.
Chem., 26 , 208 (1934)). Conversion rates reported for gas phase operations such as over phosphoric acid impregnated with diatomaceous earth Celite at 225-250°C and 550 psig are only 3.8%.
It is. Although direct hydration processing in the gas phase overcomes the main drawbacks of two-step sulfuric acid-based solution processing, it has hitherto suffered from low single-stream conversion, which is dependent on thermodynamic vapor phase equilibrium conditions. This is thought to be the result of Therefore, the reactants are in gas phase (propylene) and liquid phase (water).
Research has focused on the use of conditions that allow both. Treatment with liquid water allows for direct hydration of olefins at much higher single-stream conversions than can be achieved by gas phase operation, probably because the solubility of the product alcohol dissolved in the liquid phase This is because it changes the thermodynamic equilibrium conditions that limit the gas phase conversion rate. Catalysts that can be used in this multiphase process must then exhibit hydrothermal stability as well as catalytic activity in the presence of water in the liquid phase at a given reaction temperature. The most commonly used catalyst for this propylene hydration process known so far is tungsten oxide, but silica
Alumina and supported Group and Group metals have also been reported. Ogino ((Catalyst) 4 , 73 (1962) J.CATAL.,
8, 64 (1967)) is a metal sulfate-silica gel catalyst effective for the hydration of propylene, especially Fe, Al, Cr, Cu,
We have discovered sulfate-silica gel catalysts of Zn, Co, Pb, Ni, Mn and the like. He concluded that an acidity range of 1.5 to -3 H ₀ was most suitable using these catalysts. However, the method used to determine the surface acidity of the catalyst based on the color change of the indicator dye must be considered unreliable.
That is, there is no clear indication available as to what to expect with highly acidic solid catalysts, especially solid superacids. Sulfone-based cation exchange resins have also been proposed as catalysts for propylene hydration. Japanese Unexamined Patent Publication 1972-
Publication No. 151106 (Chemical Abstracts 88,
169578x) discloses the use of halogenated cation exchange resins of the sulfonic acid type to hydrate lower olefins to form the corresponding alcohols. Example 1 of this patent publication describes the hydration of propylene over a chlorinated Amberlite 15 sulfonated styrene-divinylbenzene copolymer to produce isopropyl alcohol. The propylene conversion rate is stated to be 14.3% and the isopropanol selectivity to be 96%. A temperature of 130° C. and a pressure of 70 atmospheres (approximately 1000 psi) are required for the hydration reaction. The above-mentioned patent publication also describes the use of Nafion 501 resin from DuPont, "a perfluorovinyl ether copolymer containing sulfonic acid groups" as a catalyst. Example 2 of the aforementioned patent publication describes the use of this catalyst to hydrate 1-butene to secondary butanol with a conversion rate of 3.1%. This extremely low conversion rate is not explained, but the reason is clear considering that the commercially available Nafion 501 resin used is a potassium salt of resin sulfonic acid and is not an acid catalyst. Commercially available naphionic resins, which are potassium salts of sulfonic acid resins used in ion exchange membrane applications, are clearly unsuitable as hydration catalysts. The present invention relates to the hydration of lower ( _C2 - _C6 ) olefins in the gas phase at moderate temperatures and moderate pressures, including atmospheric pressure;
In particular, it has been discovered that the superacid solid perfluorinated sulfonic acid can be used to effectively promote the hydration of propylene to isopropyl alcohol. These catalysts include C ₁₀ -C ₁₈ perfluorinated alkanesulfonic acids, free acid form perfluorinated alkanesulfonic acid polymers such as trifluoroethylene sulfonic acid polymers, tetrafluoroethylene-trifluoroethylene sulfonic acid copolymers. A copolymer of a combined or activated free acid form of perfluoroalkenesulfonic acid and perfluorovinyl ether, such as the commercially available free acid form of Nafion resin from DuPont (referred to herein as Nafion-H). could be. These catalysts based on perfluorinated sulfonic acids (which are themselves solids) have very low or no volatility;
It has a high degree of long-term stability under the hydration conditions used, which is due to its extremely high acidity, hitherto unachievable with any solid catalyst system, and thus gives a selective and effective conversion of The temperature range of the hydration reaction of propylene promoted by perfluorinated sulfonic acids can vary between approximately 120° and 180°C, the molar ratio of water to propylene can vary from 1 to 50, and static flow The space velocity (LSHV) in the reactor can vary between about 1 and 10. Optimum conditions are found between 140°C and 160°C, a molar ratio of water to propylene between 2 and 10 and a space velocity between 2.5 and 5. The flow system can be at atmospheric pressure or under pressure. Moderate pressure (500-1000 psi) can be advantageous to increase the single stream yield of isopropyl alcohol. The reaction is preferably carried out in the gas phase over a fixed bed catalyst or as a multiphase system. Under these conditions, conversions of 15-30% of propylene to isopropyl alcohol are achieved in a single stream with selectivities of 96-99%. Optimal conditions for hydrating other lower olefins can be routinely determined. The perfluorinated solid alkanesulfonic acids used as catalysts in the present invention can be produced by various methods.
The perfluorinated alkanesulfonyl fluoride can be prepared in a variety of ways, such as by the use of electronic fluorination to prepare the corresponding perfluorinated alkanesulfonyl fluoride;
Journal of the Chemical Society (1947), 2640
-2645 can be hydrolyzed to the related alkanesulfonic acids. Alternative methods of preparing the catalyst include reacting perfluorinated alkyl iodides (R _F I) with sulfur dioxide by their Gunylyal reaction or adding sulfonyl halides to perfluorinated olefins. Trifluoroethylene sulfonic acid polymers are described in US Pat. No. 3,041,317 (CA 58 451a).
Trifluoroethene-fluorinated sulfone polymers can be prepared by a variety of methods including hydrolysis with water and strong base (NaOH or KOH). This hydrolysis forms an alkali salt of the polymeric sulfonic acid, from which treatment with NHO ₃ or H ₂ SO ₄ releases the effective acid form of the sulfonic acid. Tetrafluoroethylene-trifluoroethylene sulfonic acid copolymers are similarly prepared according to British Patent No. 1184321 (Chem, Abst, 73 , 15936V). Commercially available Nafion trade name ion exchange membrane resins, such as Nafion 501 manufactured by DuPont, are perfluorinated polymers having sulfonic acid groups in an amount of about 0.01 to 5 mole equivalents/g catalyst. The polymeric resin is a potassium salt with a repeating structure and can be specified as follows; or (In the formula, the ratio of x and y varies from about 2 to about 50,
m is 1 or 2). Polymers of the above structure can be prepared in various ways. One method described in US Pat. Nos. 3,282,875 and 3,882,093 consists of polymerizing the corresponding perfluorinated vinyl compounds. Polymeric catalysts can also be prepared by copolymerizing the corresponding perfluorinated vinyl ethers with perfluoroethylene and/or perfluoro-α-olefins according to US Pat. No. 4,041,091. Commercially available Nafion resins can be converted to their acid form (referred to as Nafion-H for distinction) by repeated treatment with hydrous strong acids such as nitric acid or sulfonic acid. A superacid is an acid with an H ₀ greater than -11, such as -25, on the Hammett scale. i.e. sulfuric acid (−11 H ₀ )
or exclude weaker acids such as HF (-10 H ₀ ). The present invention will be illustrated by the following examples, which are included for illustrative purposes only and should not be construed as limiting the invention in any way. Although the examples use the preferred olefin propylene, the invention is generally applicable to other olefins, especially lower olefins having up to 6 carbon atoms. Example 1 10g perfluorohexadecanesulfonic acid
C ₁₆ F ₃₃ SO ₃ H is deposited on 75 g of porous chromosorb by vacuum evaporation. 5 g of this catalyst are charged into a stainless steel contact tube reactor with dimensions 170 x 12 mm. Heat the reactor to 135°C,
Propylene (8 g/hr) and water (25 g/hr) are passed under a pressure of 700 psig. Isopropyl alcohol was obtained with a propylene conversion of 23% and a selectivity of 96%. Example 2 10g perfluorodecanesulfonic acid
Deposit C ₁₀ F ₂₁ SO ₃ H onto 90 g of porous alumina. 50 g of this catalyst are reacted under the conditions of Example 1 to obtain a 25% conversion of propylene to isopropyl alcohol with a selectivity of 97%. Example 3 97% using 10 g of perfluorodecanesulfonic acid C ₁₂ F ₂₅ SO ₅ H as catalyst under the conditions of Example 1.
to obtain a selective conversion of 25% to isopropyl alcohol. Example 4 Fixed bed glass contact tube reactor (150 x 8 mm)
Charge 10 g of polymeric trifluoroethylene sulfonic acid catalyst to the reactor. Propylene (10 g/h) and steam (30 g/h) are passed over the catalyst heated to 150°C. Isopropyl alcohol is obtained with a propylene conversion of 18% and a selectivity of 96%. Example 5 The reaction is carried out as in Example 4, except that a tetrafluoroethylene-trifluoroethylene sulfonic acid polymer is used as the catalyst. Isopropyl alcohol is obtained with a propylene conversion of 15% and a selectivity of 98%. Example 6 50 g of commercially available Nafion-K resin (ion exchange membrane material manufactured by Dupont made from potassium salt) was
Reflux in 250 ml deionized water for 2 hours. After aging, the resin is treated with 100 ml of 20-25% nitric acid for 5 hours at room temperature. The nitric acid treatment is repeated three times. Finally, the resin is washed with deionized water until neutral and dried in a vacuum drying oven at 105° C. for 24 hours. 5 g of the activated Nafion H catalyst are placed in a fixed bed glass contact tube reactor with dimensions of 150 x 8 mm. Propylene (10 g/h) and water (30 g/h) are passed over the catalyst heated to 150°C. Isopropyl alcohol is obtained with a propylene conversion of 16% and a selectivity of 97%. Example 7 A fixed bed contact reactor made of stainless steel with dimensions of 170 x 12 mm is charged with 5 g of the Nafion-H catalyst prepared as in Example 6. Heat the reactor to 130°C,
Propylene (8 g/hr) and (125 g/hr) are passed under a pressure of 500 psig. Isopropyl alcohol is obtained with a propylene conversion of 31% and a selectivity of 96%. Although the invention has been described with reference to preferred embodiments, it is not intended to limit the invention to any particular form, but on the contrary to cover alternatives, modifications and equivalents as will be apparent to those skilled in the art. It is intended that

Claims (1)

Claims: 1. Treating the lower olefin with water over a superacid catalyst of solid perfluorinated sulfonic acid in the gas phase for a period sufficient to hydrate the lower olefin to the corresponding alcohol. A method for hydrating lower olefins to the corresponding alcohols, comprising contacting them with the corresponding alcohols. 2. Claim 1 comprising treating or contacting propylene with water over a solid perfluorinated sulfonic acid superacid catalyst for a period sufficient to hydrate the propylene to the corresponding isopropyl alcohol. The method described in section. 3. The method of claim 1 using a superacid catalyst of _{3 C10} to _C18 perfluorinated alkanesulfonic acids. 4. The method according to claim 1, which uses a polymeric perfluorinated ethylene sulfonic acid superacid catalyst. 5. The method according to claim 1, wherein a superacid copolymer of tetrafluoroethylene-trifluoroethylene sulfonic acid is used as a catalyst.