KR20090049656A - Process for preparing n-butanol - Google Patents

Abstract

According to the present invention, a copper-based catalyst is used to directly vapor-phase hydrogenate n-butanoic acid alone or under a reaction condition that does not use water, or a part such as n-butyl ester of n-butanoic acid or n-butanoic anhydride In the process of directly gas-phase hydrogenation of n-butanoic acid containing a carbonic acid derivative, there is provided a hydrogenation method capable of producing n-butanol with high selectivity and high space yield under the suppression of side reactions. Specifically, the present invention is a method for producing n-butanol, comprising directly gas phase reduction of n-butanoic acid with hydrogen on a reduced copper-based catalyst, wherein the reduced-type copper-based catalyst is silica, alumina, titania. And a copper-based catalyst obtained by reducing a complex oxide of at least one diluent selected from the group consisting of zinc oxide and copper oxide, or cobalt, zinc, manganese, ruthenium, rhenium, palladium, platinum, silver, tellurium A catalyst further comprising at least one improved component selected from the group consisting of rulium, selenium, magnesium, and calcium, wherein the content of the copper oxide component is 40-95 wt% and the copper oxide particle size is 50 nm or less.

n-butanoic acid, n-butanol, biobutanol, reduced copper catalyst

Description

Production method of n-butanol {PROCESS FOR PREPARING n-BUTANOL}

The present invention relates to a method for preparing n-butanol from n-butanoic acid, and specifically, n-butanoic acid under direct catalytic gas phase hydrogenation under a copper-based catalyst having limited properties. It relates to a method for producing butanol.

Due to the depletion of petroleum resources and the rise of global environmental issues, research on the deoiling of automobile fuels has been continuously conducted, and bioethanol is currently used in some countries as an alternative fuel for transporting petroleum. On the other hand, biobutanol has no problems of corrosion or low boiling point of bioethanol, and can be used without special modification of automobile system using petroleum fuel, and has higher volumetric fuel efficiency than bioethanol. A fuel having a number of advantages, but the biobutanol manufacturing process is still low yield and productivity compared to the bioethanol manufacturing process, has not been developed a bio process that can be economically produced.

Accordingly, as an alternative to the biobutanol manufacturing process, n-butanoic acid is produced by bioprocessing from biomass, a natural circulation resource, and n-butanol is reduced by catalytic chemical method to reduce n-butanol. Bio-chem compounding techniques are being considered.

   Meanwhile, n-butanol has been produced in large quantities through a hydrogenation reaction after hydroformylation of propylene in a petrochemical process, and has been used in the manufacture of solvents, plasticizers, amino resins, butylamines, and the like.

It is a chemically easy reaction to produce a primary alcohol such as n-butanol by reducing a carboxylic acid such as n-butanoic acid. However, such chemical reduction reactions require the use of expensive and powerful reducing agents such as lithium aluminum hydride (LiAlH ₄ ), so that reduction reactions using such reducing agents can be carried out on an industrial scale for general purpose primary alcohols such as n-butanol. Not suitable for production

On the other hand, a hydrogenation reaction using hydrogen as a reducing agent on a hydrogenation catalyst is used to produce a primary alcohol on an industrial scale. However, such a hydrogenation reaction is not usually applied to direct hydrogenation of carboxylic acid, which is generally used because the hydrogenation catalyst is dissolved in the reactant carboxylic acid to maintain the catalytic activity in the presence of carboxylic acid for a long time, Or because the catalyst component causes decarbonation of the carboxylic acid so that the direct hydrogenation of the carboxylic acid has low selectivity.

Accordingly, most of the carboxylic acid hydrogenation processes are prepared by a two-step process in which a carboxylic acid is esterified with methanol or ethanol, and the esterified product is hydrogenated to produce a primary alcohol [for example, 1,4-butanediol is prepared by hydrogenation of esters of maleic acid, maleic anhydride with methanol or ethanol (USP 6,100,410, USP 6,077,964, USP 5,981,769, USP 5,414,159, USP 5,334,779).

  However, such a process requires the addition of an esterification step, recovery of alcohol used for the esterification reaction, and purification step for hydrogenation of the carboxylic acid, and recovery and purification of unreacted esterified product after the hydrogenation reaction. There are problems such as complexity and disadvantages in terms of production cost.

  Because of these problems, much research is being done to shorten the reaction process in producing primary alcohols.

  For example, US Pat. No. 6,495,730 and the patent cited in the patent disclose a hydrogenation catalyst system for producing 1,4-butanediol by directly hydrogenating maleic acid or succinic acid under reaction conditions in which excess water is supplied relative to carboxylic acid. Are known [ruthenium-tin / activated carbon; Ruthenium-iron oxide; Ruthenium-tin / titanium or alumina; Ruthenium-tin and a component selected from alkali metals or alkaline earth metals; A component selected from tin-ruthenium, platinum and rhodium; Ruthenium-tin-platinum / active carbon].

On the other hand, in USP 4,443,639, ruthenium-based catalysts of ARuDEO _x (A = Zn, Cd, Ni and mixtures thereof, E = Fe, Cu, Rh, Pd, Os, Ir, Pt and mixtures thereof) as hydrogenation catalysts of n-butanoic acid It discloses that n-butanol is obtained when water is present, but n-butyl butyrate is obtained when there is no water.

That is, the prior art requires the use of excess water to prepare a primary alcohol from carboxylic acid (USP 4,443,639: 10 wt% acid aqueous solution), which generates a large amount of waste water, high energy use costs, low productivity (e.g., LHSV: 0.1 hr ^-1 or less) There are problems such as high hydrogenation pressure.

  Accordingly, there is a demand for the development of economical manufacturing process technology for the industrial production of n-butanol by hydrogenation of n-butanoic acid.

Accordingly, it is an object of the present invention to directly hydrogenate n-butanoic acid alone or to n-butyl esters of n-butanoic acid or n-butanoic acid under specific reaction conditions using no specific catalyst. In the process of hydrogenating n-butanoic acid containing the same butanoic acid derivative, it is to provide a hydrogenation method capable of producing n-butanol with high selectivity and high space yield under the inhibition of side reactions.

In order to achieve the above object, the present invention provides a method for producing n-butanol, characterized in that the n-butanoic acid is directly reduced by a gas phase hydrogenation reaction on a copper-based catalyst that satisfies specific conditions as described below.

In the present invention, the copper-based catalyst means all catalysts mainly containing copper such as copper-silica, copper-alumina, copper-titania, copper-zinc oxide, and copper-chromium.

Specifically, the present invention is a method for producing n-butanol comprising directly gas-phase reduction of n-butanoic acid by hydrogen on a reduced copper-based catalyst, wherein the reduced-type copper-based catalyst includes silica, alumina, titania and A copper catalyst obtained by reducing a complex oxide of at least one diluent selected from a group consisting of zinc oxide and a copper oxide component, wherein the copper oxide component is 40 to 95 wt% and manufactured to have a copper oxide particle size of 50 nm or less. Catalyst.

The copper-based catalyst can be modified by further including one or more refined components selected from the group consisting of cobalt, zinc, chromium, manganese, ruthenium, rhenium, palladium, platinum, silver, tellurium, selenium, magnesium and calcium. Can be.

 Further, in the n-butanol production method, n-butanoic acid containing n-butanoic acid alone or n-butanoic acid derivatives may be used as a reactant.

According to the process for producing n-butanol of the present invention, a specific reduced copper-based catalyst is used to directly hydrogenate n-butanoic acid alone or under reaction conditions without using water, or n-butanoic acid or n-part anhydride By hydrogenating n-butanoic acid containing butanoic acid derivatives such as n-butyl ester of carbonic acid, n-butanol can be produced with high selectivity and high space yield while suppressing side reactions, and thus n-butanol is an economical method. It can be prepared as.

In general, in the reaction for producing an alcohol by hydrogenation of an organic carboxylic acid or anhydrides or esterified substances thereof, it is advantageous to obtain an appropriate reaction rate by increasing the reaction pressure, and to keep the reaction temperature as low as possible. This is because the selectivity is lowered because the alcohol, which is a product, is dehydrated on the catalyst at a high temperature. Therefore, it is necessary to keep the reaction temperature low in order to suppress such dehydration reaction and obtain a target product in high yield. However, in the case of the hydrogenation of the esterification, since the hydrogenation usually proceeds at a reaction temperature of 140-200 ° C., the above-mentioned meaning is significant. Due to the strong interaction between the carboxyl group and the metal as a reducing catalyst, the reaction temperature at which the carboxylic acid is reduced is much higher than that of the esterified product. In addition, in order to obtain an appropriate reaction rate, it is necessary to keep the reaction pressure high. In this case, in order to avoid n-butanoic acid contacting the catalyst in a liquid phase to free the catalyst component or particle growth to deactivate the catalyst, the n-butanoic acid should always be in contact with the catalyst in a gaseous state.

Therefore, in order for n-butanoic acid to exist in the gas state under high pressure conditions, it is necessary to maintain an excess hydrogen flow condition compared to n-butanoic acid, which means that hydrogenation of n-butanoic acid can be achieved within a short contact time. To satisfy this, the catalyst must have high activity. On the other hand, in order to reduce the energy cost and obtain the target product in high yield, the reaction temperature and the pressure will be preferable as low as possible.

In order to produce n-butanol in high yield and high productivity by gas phase reduction of n-butanoic acid under the above-described preconditions, the copper-based catalyst of the present invention has a content of copper oxide (precursor of copper component) in the catalyst composition. 40 to 95 wt%, preferably 50 to 90 wt%, and should be a catalyst prepared to have a particle size of copper oxide of 50 nm or less, preferably 30 nm or less, more preferably 20 nm or less. . In addition, silica, alumina, titania, zinc, and the like are used as the diluent together with the copper component, which is not a carrier in a conventional catalyst and is itself a nano-sized microparticle which is complexed with the copper component to form fine copper particles. The particle migration of the catalyst should be suppressed to make the catalyst thermally stable.

The hydrogenation of n-butanoic acid is carried out at a reaction temperature of 200 to 350 ° C., preferably 220 to 300 ° C., whereas the particle migration of the fine copper particles, which is the main component of the catalyst, starts at about 180 ° C. [Topic in Catalysis 8 (1999) 259]. Therefore, the catalyst used in the present invention is less efficient when prepared by the supporting method, it is efficient to prepare by the co-precipitation method or sol-gel method in order to obtain a compounding effect.

In the case of gas phase hydrogenation of n-butanoic acid on a copper-based catalyst having the above-described properties, unlike the use of water in the above-mentioned patent documents, it is necessary to directly hydrogenate n-butanoic acid without using water. Butanol can be obtained with high productivity and high yield.

In the present invention, the gaseous hydrogenation conditions of n-butanoic acid on the catalyst are carried out under a reaction pressure of 5 to 70 atm, preferably 15 to 40 atm, in addition to the above reaction temperature, and when the pressure is low, the conversion rate is low and high. It is not preferable to use excess hydrogen to maintain the gaseous state of n-butanoic acid. In addition, the molar ratio of H ₂ / n-butanoic acid is 10 to 200: 1, preferably 20 to 150: 1, and when it is lower than this, it is difficult to maintain the gaseous state of n-butanoic acid, and when higher than this, excess hydrogen is recovered. This is undesirable because it must be reused. a feed rate (LHSV) of n- butanoic acid is 0.05 ~ 5hr ^-1, preferably 0.2 ~ 2hr ^-1.

In the present invention, the preferred catalyst is a catalyst for obtaining high selectivity by inhibiting dehydration of n-butanol as a product, considering that the hydrogenation of n-butanoic acid is performed at 200 ° C. or higher, in particular at 220 to 300 ° C. It is desirable to have weighting properties, and in this regard, a copper-silica composite catalyst in which the diluent is composed of silica of nanoparticles is effective in achieving the object of the present invention.

More preferably cobalt, zinc, chromium, manganese, ruthenium, rhenium, palladium, platinum, silver, tellurium, selenium, magnesium and Catalysts modified with at least one of the components, such as calcium, are more effective. The modifier component is based on the copper oxide content It is preferable to use it at 20 wt% or less, and the catalyst performance is rather poor when used in excess.

In the n-butanol preparation method of the present invention, the reactant may be used alone n-butanoic acid for the purpose of the present invention, but the n-butanoic acid or n-butanoic acid derived from n-butanoic acid together with n-butanoic acid The case where the butyl ester is mixed and supplied is also included in the scope of the present invention.

In the n-butanol production method of the present invention, the catalyst is usually prepared in the form of an oxide and filled in the reactor, and the activation is reduced by raising the temperature to 250 to 300 ° C. under a stream of hydrogen gas diluted with nitrogen before carrying out the reduction reaction. Go through the process.

Hereinafter, the present invention will be described in more detail with reference to Examples. However, the scope of the present invention is not limited to the following examples.

By weight herein (wt%) is used unless otherwise indicated in the content of each component of the catalyst.

[ Example ]

Example  One

Catalyst: CuO (80) SiO ₂ (20)

Solution A was prepared by dissolving 50 g of copper nitrate [Cu (NO ₃ ) ₂ .3H ₂ O] in 200 ml of deionized water. Aqueous solution of sodium hydroxide was added to 100 ml of deionized water to adjust the pH to 9.2, and solution B in which 13.75 g of colloidal silica Ludox SM-30 was added thereto was prepared, and solution C was prepared by dissolving 16.6 g of sodium hydroxide in 200 ml of deionized water. In the reactor to which the stirrer is attached, solutions A, B, and C are simultaneously added dropwise to carry out the precipitation process at 20 ° C. or lower. Thereafter, the obtained slurry solution was hydrothermally aged for 6 hours while being heated to 85 ° C. The resulting slurry was washed with deionized water sufficiently, filtered and the cake obtained was dried at 120 ° C. for 12 hours and then powdered.

The powder obtained was crushed to a size of 20 to 40 mesh after pressure molding, and then calcined at 600 ° C. for 6 hours to obtain an oxide catalyst. The copper oxide particle size of the catalyst was 4 nm, as measured by the XRD line broading method. 1.0 g of the catalyst was charged in a tubular reactor (ID = 7 mm) and heated to 280 ° C. while flowing N ₂ gas containing 5% H ₂ to activate the catalyst. Thereafter, the reactor temperature and pressure were adjusted to 265 ° C. and 370 psi, and the reaction was performed while supplying n-butanoic acid at a rate of 0.9 cc / hr under a hydrogen gas flow of 130 ml / min. 24 hours after the initiation of the reaction, the conversion rate of n-butanoic acid was 99.9%, the selectivity of n-butanol was 94.3%, and the selectivity of butyl n-butanoic acid was 3.2%.

Example  2

Catalyst: CuO (80) -ZnO (20)

50 g of copper nitrate [Cu (NO ₃ ) ₂ · 3H ₂ O] and 15.05 g of zinc nitrate [Zn (NO ₃ ) ₂ · 6H ₂ O] were dissolved in 200 ml of deionized water and 20.6 g of sodium hydroxide in 200 ml of deionized water. To prepare a solution B in which was dissolved. Co-precipitation was performed by dropwise adding solutions A and B to the reactor to which the stirrer was attached. The subsequent procedure was the same as in Example 1, and the catalyst was calcined at 450 ° C. for 6 hours to obtain an oxide catalyst. The particle size of the copper oxide was 12 nm as measured by the XRD line broadening method.

1.0 g of the catalyst was charged in a tubular reactor and activated in the same manner as in Example 1, followed by reaction under the same reaction conditions. 24 hours after the start of the reaction, the reactivity was 98.2% in n-butanoic acid conversion, 81.5% in n-butanol, and 18.2% in butyl n-butanoic acid.

Example  3

Catalyst: CuO (80) SiO ₂ (10) TiO ₂ (10)

The catalyst was prepared in the same manner as in Example 1. However, TiO ₂ was used as a precursor of titanium (IV) isopropoxide [Titanium (IV) isopropoxide], which was dissolved in isopropanol. The copper oxide particle size of the catalyst calcined at 600 ° C. was 15 nm. 1.0 g of the catalyst was charged to a tubular reactor and activated in the same manner as in Example 1, and the reaction was carried out under the same conditions. 24 hours after the initiation of the reaction, the conversion rate was 99.9%, the selectivity of n-butanol was 94.5%, and the selectivity of butyl n-butanoate was 1.3%.

Example  4

Catalyst: CuO (80.4) CoO (3.0) ZnO (0.2) CaO (0.2) MgO (0.2) TeO ₂ (0.02) SiO ₂ (16.0)

50 g of copper nitrate [Cu (NO ₃ ) ₂ .3H ₂ O] in 200 ml of deionized water, 2.3 g of cobalt nitrate [Co (NO ₃ ) ₂ .3H ₂ O], zinc nitrate [Zn (NO ₃ ) ₂ .3H ₂ O Solution A was prepared by dissolving 0.15 g. Aqueous solution of sodium hydroxide was added to 100 ml of deionized water to adjust the pH to 9.2, and solution B in which 11 g of colloidal silica Ludox SM-30 was added thereto was prepared, and solution C in which 17.3 g of sodium hydroxide was dissolved in 200 ml of deionized water was prepared. The solution A, B, and C were simultaneously added dropwise to the reactor to which the stirrer was attached, and coprecipitation was performed at 20 ° C. or lower. At this time, the pH was adjusted by adjusting the acceleration rate of the solution C, and the final pH of the slurry solution was adjusted to 9.30 after completion of coprecipitation. Thereafter, after hydrothermal aging at 85 ° C. for 6 hours, the resulting slurry was sufficiently washed with deionized water, filtered and the precipitate was recovered. To the cake obtained, 0.13 g calcium acetate [Ca (OAc) ₂ H ₂ O], 0.22 g magnesium acetate [Mg (OAc) ₂ 4H ₂ O] and telluric acid [Te (OH) ₆ ] 0.006 g were removed. The solution dissolved in deionized water was added, mixed, dried at 120 ° C. for 12 hours, and then powdered. The powder was crushed to a size of 20 to 40 mesh after pressure molding, and fractionated and calcined at 600 ° C. for 5 hours to obtain an oxide catalyst. The copper oxide particle size of the catalyst was 5.6 nm as measured by the X-ray diffraction line broadening method.

1.0 g of the catalyst was charged to a tubular reactor, activated in the same manner as in Example 1, and then reacted under the same reaction conditions. 24 hours after the start of the reaction, the conversion of n-butanoic acid was 100%, the selectivity of n-butanol was 96.2%, and the selectivity of butyl n-butanoic acid was 1.4%.

Example  5

The same procedure was followed in Example 1 except that n-butyl acid: butyl anhydride = 50: 50 (w / w) was used instead of n-butyl acid as the reactant.

24 hours after the initiation of the reaction, the conversion of n-butanoic acid was 100%, the selectivity of n-butanol was 96.0%, and the selectivity of butyl n-butanoate was 1.2%.

Claims (10)

A process for producing n-butanol, comprising directly gas-reducing n-butanoic acid with hydrogen on a copper catalyst. The copper-based catalyst is obtained by reducing a composite oxide of a copper oxide component and at least one diluent selected from the group consisting of silica, alumina, titania and zinc oxide, and the content of the copper oxide component in the catalyst is 40 to 95. wt% and the particle size of the copper oxide is 50 nm or less, characterized in that the manufacturing method of n-butanol. The method of claim 1, wherein the catalyst further comprises at least one improved component selected from the group consisting of cobalt, zinc, chromium, manganese, ruthenium, rhenium, palladium, platinum, silver, tellurium, selenium, magnesium and calcium. Characterized in that it is modified by including, a process for producing n-butanol. The method for producing n-butanol according to claim 1 or 2, wherein the catalyst is a reduced copper-silica catalyst. The method for producing n-butanol according to claim 1 or 2, wherein the content of the copper oxide component in the catalyst composition is 50 to 90 wt%. The process for producing n-butanol according to claim 1 or 2, wherein the n-butanoic acid is gas phase reduced at a reaction temperature of 220 to 300 ° C and a reaction pressure of 5 to 70 atm. The method for producing n-butanol according to claim 1 or 2, wherein the molar ratio of hydrogen (H ₂ ) / n-butanoic acid is 10 to 200: 1. The method for producing n-butanol according to claim 6, wherein the molar ratio of hydrogen (H ₂ ) / n-butanoic acid is 20 to 150: 1. The process for producing n-butanol according to claim 1 or 2, wherein the feed rate (LHSV) of n-butanoic acid is 0.05 to 5 hr ⁻¹ . The method for producing n-butanol according to claim 2, wherein the content of the improved component is 20 wt% or less with respect to the copper oxide content. The preparation of n-butanol according to claim 1 or 2, wherein the complex oxide for preparing the copper-based catalyst is reduced and activated at a temperature of 250 to 300 ° C under a flow of hydrogen gas diluted with nitrogen. Way.