KR920003916B1 - Composition of aldehyde hydrogenation catalyst - Google Patents

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Description

Aldehyde Hydrogenation Catalyst Composition

The present invention relates to a process for the catalytic hydrogenation of aldehydes with alcohols. The present invention relates, in particular, to improved catalysts and catalytic processes for hydrogenating aldehydes to alcohols, a major improvement in selectivity being evidenced by the reduction in the production of undesirable byproducts.

Hydrogenation of aldehydes that produce alcohol has been practiced for a long time. Typically the reaction of aldehydes with hydrogen is carried out in the presence of certain reduced metal complexes which act as hydrogenation catalysts. Commercial hydrogenation catalysts commonly used include copper chromate; Cobalt compounds; Nickel; Nickel compounds which may contain small amounts of chromium or other promoters; Mixtures of copper with nickel and / or chromium; And a mixture of reduced copper oxide-zinc oxide (ie, copper-zinc oxide).

Naturally, when using the above-mentioned hydrogenation catalysts to hydrogenate aldehydes with alcohol, all of these hydrogenation catalysts all have one or more disadvantages. The selectivity of most catalysts, such as copper chromate, cobalt compounds, nickel catalysts and reduced copper oxide-zinc oxide catalysts, is lower than the desired selectivity. That is, when hydrogenating an aldehyde using such a catalyst, the amount of by-products formed may be more than the desired amount. These by-products reduce the desired selectivity of the conversion of aldehydes to alcohols, and usually byproducts must be removed from the hydrogenation product prior to continuous use of the alcohols (see European Patent Publications 0 008 767 and 0 074 193). . Moreover, copper chromite catalysts are difficult to manufacture, the toxicity issues associated with their use are severe, and cobalt compounds are quite expensive.

When using nickel catalysts, the main by-products are ethers and hydrocarbons (paraffins), and esters are produced as main by-products when using reduced copper oxide-zinc oxide catalysts. The amount of byproduct formed may be from about 0.5 to about 3.0 weight percent and more based on the total weight of the reaction product.

For example, in a method of catalytic hydrogenation of butyraldehyde to butanol over a nickel catalyst, a small amount of butyl ether is formed while by-products are reduced when using a reduced copper oxide-zinc oxide catalyst for the same reaction. Small amounts of butyl butyrate are produced. The ether forms an azeotrope with the water present in the alcohol hydrogenation product and often the product from the feed stream. Thus, a substantial amount of energy is required to separate the byproduct ether from the alcohol, and typically a significant amount of alcohol is lost. For example, the separation of butyl ether from butanol, which is necessary for butanol to pass pure standards such as specifications for the manufacture of acrylates, requires a series of expensive distillation steps, and butyl formed by the butylether-butanol azeotrope 4 lbs butanol is lost per pound of ether. This loss may lead to the use of commercially unfavorable, other advantageous hydrogenation catalysts.

While byproduct esters can be more easily removed, separation costs and associated losses are inevitable. Due to ester formation, alcohol is lost through the ester stream fused from the bottom of the alcohol, which is still purified in a typical recovery process. European Patent Publication No. 0 074 193 to avoid such losses, recovering and concentrating the esters and then hydrolyzing them to further alcohols in another reactor containing the reduced copper oxide-zinc oxide catalyst. The approach used in the call requires additional equipment. Moreover, the amount of ester formed is typically increased within a range of raising the temperature in the catalytic hydrogenation reactor. Therefore, when using a reduced copper oxide-zinc oxide catalyst, it may be necessary to perform the hydrogenation process at a relatively low temperature in order to minimize the formation of by-product esters. In particular, when the by-products are esters such as propyl propionate, it is necessary to carry out the hydrogenation process at relatively low temperatures since it is difficult to separate esters such as propyl propionate from the preferred alcohol using conventional class techniques. Unfortunately, running at lower temperatures reduces the rate of catalytic hydrogenation.

In addition, the reduced copper oxide-zinc oxide catalyst complicates the performance of conventional catalyst techniques due to the tendency to form higher amounts of ester at higher reaction temperatures. It is common practice to raise the reaction temperature over time to compensate for the progressive and consequent loss of hydrogenation catalytic activity over time. However, in the case of using a reduced copper oxide-zinc oxide catalyst, the formation of ester by-products is elevated due to this temperature rise, thus making the subsequent product purification process more complicated or increasing the amount of by-product ester formation above acceptable limits. In this case, the catalyst input should be changed sooner than predicted by the rate of hydrogenation.

In addition, since the reaction needs to be carried out at lower temperatures, the process is complicated by the need for a more expensive reactor or an increase in the number of adiabatic reaction steps with an internal cooler. Moreover, less useful energy is recovered from the heat of reaction at low temperatures.

As indicated above, there is a need in the art for catalytically hydrogenating aldehydes with alcohols, catalysts with improved product selectivity, particularly those that maintain high catalyst selectivity at high temperatures necessary to maximize reaction rates and energy efficiency.

The present invention provides a catalytic process for hydrogenating aldehydes with alcohols and catalysts that produce the maximum desired alcohol product and significantly reduce the formation of byproduct esters and ethers as compared to prior art catalysts. The present invention is a by-product of adding a small amount of selectivity enhancer selected from the group consisting of alkali metals, nickel, cobalt and mixtures thereof to known reduced copper oxide-zinc oxide catalysts, which is a by-product than when using catalysts that do not contain such enhancers. Based on the surprising finding that reducing the formation of esters significantly improves the selectivity of the catalyst. As noted above, byproduct esters are formed during hydrogenation on a reduced copper oxide-zinc oxide catalyst, particularly at elevated temperatures, which is often desirable to maximize reaction rates and energy efficiency.

The present invention relates to an aldehyde consisting essentially of a mixture of reduced copper oxide and zinc oxide, impregnated with a minimum selectivity enhancing amount selected from the group consisting of sodium, potassium, lithium, cesium, nickel, cobalt and mixtures thereof. A heterogeneous vapor phase process for the production of alcohols by catalytic hydrogenation of the corresponding aldehydes on a hydrogenation catalyst.

According to another aspect of the invention, a mixture of an alkali metal selectivity enhancer selected from the group consisting of sodium, potassium, lithium, cesium and mixtures thereof and a transition metal selectivity enhancer selected from the group consisting of nickel, cobalt and mixtures thereof Provided is a preferred aldehyde hydrogenation catalyst composition consisting essentially of a mixture of copper oxide and zinc oxide (ie, reduced copper oxide-zinc oxide) incorporated in a minimal selectivity enhancing amount of the selectivity enhancer. The present invention also relates to a method for producing an aldehyde hydrogenation catalyst.

Disregarding other additives, the improved copper oxide-zinc oxide catalyst of the present invention may contain from about 20 to about 70 weight percent copper oxide and correspondingly from about 80 to about 30 weight percent zinc oxide before being reduced. It contains. The preferred amount of copper oxide in the pre-reduced or calcined precursor catalyst composition is in the range of about 30 to about 50 weight percent, while balancing with zinc oxide. Particularly preferred are precursor catalyst compositions having a weight ratio of copper oxide to zinc oxide of from about 1: 2 to about 1: 1.

Aldehyde hydrogenated calcined precursor catalyst compositions containing mixtures of copper oxide and zinc oxide useful in the present invention can be prepared by any one of a variety of known methods suitable for preparing catalyst materials. Thus, an initial mixture of copper oxide and zinc oxide can be prepared by mixing metal oxides together (e.g., titration or melting a mixture of oxides, followed by melting and pulverizing the solidified mass).

Preferably, the mixture is co-precipitated from an aqueous solution of copper and zinc salts of a mixture of copper and zinc compounds that can be readily converted (decomposed) into oxides, or in the presence of a thermally stable metal oxide such as, for example, alumina. Prepared by decomposition of a mixture of ammine carbonate and zinc ammine carbonate.

Useful coprecipitation processes include the precipitation of copper carbonate and zinc carbonate in the desired proportions from a solution containing soluble copper and zinc salts such as nitrates. The oxide mixture is then prepared from the coprecipitated salt using an oxidation treatment, for example firing, at elevated temperature in the presence of oxygen. The calcined product can then be formed into tablets, granules and the like of any suitable size and shape. For example, co-precipitated copper carbonate and zinc carbonate are recovered and dried, and then the dried precipitate is calcined in the presence of an oxygen-containing gas at a temperature within the range of about 550 ° to 700 ° F. Convert to form.

Prior to use as a catalyst for aldehyde hydrogenation, the catalyst is run for several hours (e.g. up to about 24 hours) in the presence of a reducing agent such as hydrogen or carbon monoxide at a temperature within the range of about 150 to 300 ° C, preferably about 230 to 260 ° C. The catalyst must be heated to reduce it. Preferably, the catalyst is reduced using a dilute hydrogen stream, typically a stream containing 1 to 5% hydrogen in a gas such as nitrogen inert to the catalyst during the reduction process. While nitrogen is the preferred diluent for reducing gases, other gases may also be used.

It is important to control the catalyst temperature during the reduction so that the temperature does not exceed about 300 ° C., preferably about 260 ° C. as a result of the copper oxide reduction exotherm. Excessive temperature during the reduction leads to lower catalyst activity. While the catalyst can be reduced prior to use in the aldehyde hydrogenation reaction, the catalyst can also be reduced during the process of converting aldehyde to alcohol. After the mixed oxide powder is reduced, the catalyst composition can be formed in the desired form, but preferably the mixed oxide is reduced to pellet, extrude, or otherwise form before use.

As generally known. Catalyst efficiency depends on various physical properties, including surface area and pore volume, which vary widely depending on how the catalyst is made. The catalyst advantageously has an internal surface area of 30 to 60 m 2 / g. Internal surface area can be measured by known BET methods.

In preparing the catalyst by coprecipitation, water-soluble mixtures of copper and zinc salts can be used, for example chlorides, sulfates, nitrates and acetates. Preference is given to using nitrates. Typically, an aqueous solution of sodium carbonate is added to a solution of copper and zinc salts for coprecipitation. In the standard practice, the prior art teaches that it is undesirable to have sodium present in the catalyst, so it is necessary to thoroughly wash out the calcined copper carbonate and zinc carbonate before firing, essentially removing all traces of alkali metal (sodium) nitrate [ References: U.S. Patent Nos. 3,303,001 (Sections 2, Lines 54 to 67), U.S. Patent Nos. 4,048,196 (Sections 6, Lines 35 to 62) and U.S. Patents 4,393,251 (Sections 4, Lines 35 through 35) Column 5, line 17)]. Nevertheless, the prior art has recognized that reduced copper acid-zinc oxide catalysts prepared by standard coprecipitation techniques will contain small amounts of sodium. See US Pat. No. 3,303,001 (paragraphs 4, 1 to 52). Line) and Canadian Patent No. 1,137,519]. However, the prior art did not recognize the advantages of known alkali metals for the selectivity of the reduced copper oxide-zinc oxide catalyst used in the aldehyde hydrogenation process when providing a selectivity enhancing amount.

In addition, mixtures of copper oxide and zinc oxide can be prepared, for example, by simultaneously decomposing the ammine complex compounds as soluble copper and zinc tetra-ammine carbonate or soluble copper and zinc di- or tri-ammine carbonate. Aqueous mixtures of copper and zinc ammine complexes with a preferred weight ratio of copper to zinc are heated for a sufficient time at temperatures within the range of 160 ° to 210 ° F. in the presence of a thermally stable metal oxide such as, for example, hydrated alumina, Unreacted carbon dioxide is liberated, followed by precipitation of the water insoluble basic carbonate. The resulting slurry is then filtered and the filter cake is calcined (see US Pat. Nos. 3,790,505 and 4,279,781, which are incorporated herein by reference).

Precursor catalyst compositions of copper oxide and zinc oxide that are suitable for preparing the improved catalyst of the present invention are commercially available. For example, suitable catalyst compositions include United Catalyst Inc. and 52-1 under the trade names G-66 (see US Pat. No. 3,303,001) and C18HC (see US Pat. No. 3,790,505). Available under the trade name Catalco. While coprecipitation and ammine decomposition are preferred methods for the preparation of catalyst precursors, any method known in the art for forming a mixture of copper oxide and zinc oxide can be used.

In accordance with the present invention, a reduced copper oxide-zinc oxide catalyst or catalyst precursor is modified by adding a selectivity enhancer with a minimum selectivity enhancing amount selected from the group consisting of sodium, potassium, lithium, cesium, nickel, cobalt and mixtures thereof. Within the broad scope of the present invention, selectivity enhancers can be added to the catalyst composition in a variety of ways, and the term "impregnating" as used in the specification and claims encompasses all of these methods.

For example, when preparing a precursor catalyst composition by adding a selectivity enhancer as a water-soluble salt of the selectivity enhancer to a coprecipitation solution of a copper oxide and zinc oxide precursor compound (such as copper carbonate and zinc carbonate), It may be impregnated or incorporated into the precursor catalyst composition. When drying the precipitated salts, the enhancer can be co-precipitated with the copper and zinc salts or the residue of the selectivity enhancer can be dispersed in the precipitated copper and zinc salts. In addition, after recovering the coprecipitated copper and zinc salts, the selectivity enhancer (s) may be mixed with the coprecipitated copper and zinc salts or impregnated with the copper and zinc salts before or after drying. The treated composition is then calcined to convert the precipitated or impregnated selectivity enhancer salt together with copper and zinc salts into the oxide form of the selectivity enhancer salt.

In addition, the selectivity enhancer (s) catalyst precursor. That is, it can be added to a mixture of copper oxide and zinc oxide. For example, calcined catalyst precursors, preferably powdered or calcined catalyst precursors, available from commercial catalyst suppliers, are wetted with an aqueous solution of selectivity enhancer, dried and then calcined to convert the selectivity enhancer into its oxide form. You can switch. Also, as pointed out below, depending on the specific selectivity enhancer used and the form thereof, in some cases the firing of the treated catalyst precursor should be avoided. However, in a further variant method, which is useful when there is no need to calcinate the residue of the selectivity enhancer, the selectivity enhancer may be added directly to the reduced copper oxide-zinc oxide catalyst. Preferably, the catalyst precursor composition is impregnated with an aqueous solution of the selectivity enhancer to impregnate the selectivity enhancer with the catalyst. For example, an aqueous slurry of powdered catalyst precursor composition and selectivity enhancer may be spray dried to form a powder suitable for forming catalyst pellets. Using this technique, the amount of selectivity enhancer added to the catalyst and the uniform dispersion of the selectivity enhancer in the catalyst can be controlled.

Alkali metal selectivity enhancers can be incorporated into the catalyst as hydroxides or any salt that produces an alkali metal oxide after firing. One suitable alkali metal salt used to impregnate the catalyst is readily available and is a water soluble nitrate. Alkali metal enhancers can also be added as their carbonates and bicarbonates. Standard firing processes can be used to convert alkali metal compounds into their oxide forms. Subsequent reduction of the catalyst precursor converts the alkali metal oxide to an alkali metal hydroxide. Other alkali metal compounds suitable for impregnating a catalyst for use in the present invention will be apparent to those skilled in the art.

While not intending to be limited to any particular explanation, the inventors believe that the alkali metal selectivity enhancer is present in the catalyst in its hydroxide or hydrated oxide form. Thus, alkali metal hydroxides may be used to incorporate the alkali metal into the catalyst precursor or calcined or reduced catalyst. In this latter case, a gentle drying step is sufficient instead of firing to prepare the catalyst.

The alkali metal selectivity enhancer (s) is based on about 0.05 to 7.0 weight percent (based on the total free alkali metal), preferably about 0.5 to 3.5 weight percent (based on the precursor catalyst composition of copper oxide and zinc oxide). It is added to the catalyst in an increase in selectivity. Typically, when the amount of alkali metal addition increases to its upper limit, the activity of the catalyst decreases. Furthermore, catalysts impregnated with certain alkali metals such as sodium are less active than catalysts impregnated with similar amounts of another alkali metal such as potassium. Therefore, in such an environment, a lower amount of sodium should be used. Actual catalytic activity can be measured using routine experimentation.

Preferably, the alkali metal is potassium, which may be added to the copper oxide-zinc oxide catalyst precursor in the form of a degradable salt such as potassium hydroxide or potassium carbonate, potassium bicarbonate or potassium nitrate. The precursor catalyst composition is calcined to convert the decomposable alkali metal salt into its oxide form. For example, in the case of potassium carbonate, it is thought that potassium oxide is formed during aqueous phase. When hydrogen is used to continuously reduce the catalyst, during the hydrogen-copper oxide reduction reaction, the oxide reacts with the released water and is converted into the hydroxide form.

Also, as noted, transition metals nickel and cobalt are selectivity enhancers according to the present invention. Again, various impregnation processes can be used to obtain nickel or cobalt enhanced catalysts. Typically, the precursor catalyst composition, preferably the calcined precursor catalyst composition, is immersed in an aqueous solution of salt of nickel or cobalt as a powder or preformed tablet or granule, and then the catalyst is dried to impregnate the transition metal in the catalyst. The salt used should form nickel oxide or cobalt oxide after firing. For example, an aqueous slurry of catalyst precursor composition and nickel nitrate may be spray dried to a powder and then calcined at about 700 ° F. Nickel or cobalt selectivity enhancers may also be added to the catalyst by including small amounts of suitable water soluble salts in the original copper and zinc salt solution to be coprecipitated. In addition, other methods of impregnating the catalyst with nickel and cobalt will be apparent to those skilled in the art.

It has been found that it is most effective to lightly impregnate these transition metals with the reduced copper oxide-zinc oxide catalyst. Typically, nickel or cobalt salt should be applied in an amount sufficient to provide a selectivity enhancing amount of about 0.5 to about 5.0 weight percent, preferably about 1 to about 4 weight percent, based on the calcined precursor catalyst composition. By using such low amounts of nickel and cobalt selectivity enhancers, the modified, reduced copper oxide-zinc oxide catalyst first avoids the tendency to form the undesirable ethers and paraffins of the nickel or cobalt catalysts.

Particularly preferred aspects of the invention include a reduced copper oxide-zinc oxide catalyst impregnated with an alkali metal selectivity enhancer and a transition metal selectivity enhancer. When used as a catalyst with hydrogen to convert aldehydes into alcohols, the use of a mixture of selectivity enhancers can be used to produce catalyst compositions that synergistically reduce byproduct ester formation and continue to form no essential ethers or paraffins at all. It turned out. Moreover, the maximum benefit of this enhanced catalyst composition is observed at higher temperature reaction conditions and at reduced residence time (ie, lower space velocities), where the selectivity of commercially reduced copper oxide-zinc oxide is significantly reduced.

When used in mixtures, the amount of alkali metal, preferably potassium, to be contained in the catalyst composition is based on about 0.05 to 7.0 weight percent, preferably 0.3, based on the weight percent free alkali metal in the calcined precursor catalyst composition. To 3.5% by weight, while the transition metals nickel and / or cobalt are in an amount of about 0.5 to about 5.0% by weight, preferably 1.0 to 4.0% by weight (based on the weight% of the fired precursor catalyst composition) exist. Particularly preferred catalyst compositions contain about 0.6 weight percent potassium and about 1.5 to 2.5 weight percent nickel.

Without wishing to be bound by any particular theory, the inventors believe that the addition of nickel or cobalt transition metal selectivity enhancers to alkali metal-containing catalysts reduces ester formation due to two different reaction mechanisms. At long residence times, the discharge fraction of the hydrogenation reaction is first thought to contain alcohols and ester formation near the reactor outlet comprises forming hemiacetals from aldehydes and alcohols and then dehydrating the hemiacetals with esters. . On the other hand, it is also known that one ester can be formed from two aldehyde molecules according to the known Tischenko reaction. This reaction is assumed to occur near the inlet of the reactor where the concentration of aldehyde is highest. Obviously, nickel or cobalt transition metal selectivity enhancers can best inhibit the first ester-forming mechanism occurring near the reactor outlet, while alkali metal selectivity enhancer impregnation is directed to the predominant second ester-forming mechanism near the reactor inlet. Is considered to be the most valid.

While the catalyst of the present invention can be used in an unsupported form, the catalyst of the present invention is also alumina, pumice, graphite, silicon carbide, silicon oxide, zircon oxide, titania, silica, alumina-silica, chroma, and catalyst It may contain inert supports or combinations, such as inorganic phosphates, silicates, aluminates, borate salts, which are stable under the conditions of treatment and do not adversely affect the activity or selectivity of the catalyst. It is also possible to use calcium oxide-containing cements used to provide strength or structure to the catalyst.

The catalytic process of the present invention can be used to hydrogenate aldehydes of various straight or branched, saturated or unsaturated aldehydes containing from 2 to 22 carbon atoms. The aldehyde reaction may also contain other oxygenated groups other than carboxylic acid groups. Feed stocks are mainly limited only by vaporizing high-boiling aldehydes. Suitable aldehydes are acetaldehyde, propionaldehyde, isobutyraldehyde, n-butyraldehyde, isopentylaldehyde, 2-methylpentaldehyde, 2-ethylhexaldehyde, 2-ethylbutyraldehyde, n-valeraldehyde, isovaleraldehyde , Caproaldehyde, methyl-n-propylacetaldehyde, isohexaldehyde, caprylaldehyde, n-nonylaldehyde, n-decanal, dodecanal, tridecanal, myristaldehyde, pentadecaaldehyde, palmitaldehyde, stearic Saturated aldehydes such as aldehydes and unsaturated aldehydes such as acrolein, methacrolein, etacrolein, 2-ethyl-3-propylacrolein, crotonaldehyde and the like. Aldehydes may be almost pure or mixed with components or components other than aldehydes. It is also possible to use mixtures of aldehydes.

The aldehydes or mixtures of aldehydes used can be obtained by the oxo process. Some or all of the resulting mixture of the oxo method, ie the reaction of olefins with carbon monoxide in which carbonyl groups are added to one of the carbon atoms of the olefinic groups in the presence of a catalyst, can be used. Of course, aldehydes or mixtures of aldehydes can also be obtained by methods other than the oxo method, such as oxidation of olefins or saturated hydrocarbons or aldol contact. The invention is not limited to any particular source of aldehyde.

The aldehyde in vapor phase is contacted with a hydrogenation catalyst in the presence of a hydrogen-containing gas. While almost pure hydrogen can be used alone, it is desirable in some cases to supply hydrogen mixed with other gases, preferably aldehydes and gases that are inert to the catalyst. Inert gases suitable for mixing with hydrogen are nitrogen and methane. The term "hydrogen-containing gas" includes gaseous mixtures containing hydrogen as well as nearly pure hydrogen gas.

The concentration of hydrogen in the reaction zone is not critical, but typically hydrogen should be in excess of the stoichiometric requirement for the aldehyde to be reduced. In general, the molar ratio of hydrogen to aldehyde will be about 5 to 400, preferably about 10 to 200. For aldehydes containing 2 to 8 carbon atoms, the molar ratio of hydrogen to aldehyde is in the range of about 10 to 30.

Typically, the hydrogenation reaction is carried out at a temperature of at least about 100 ° C., but can be carried out at a high temperature, such as about 300 ° C., because of the high selectivity of the catalyst according to the invention. Preferably, the reaction is carried out at a temperature in the range of about 120 to 260 ° C. This temperature range balances the competition between energy and reaction rate. The reaction can be carried out at any suitable pressure of atmospheric pressure up to about 600 psig. In view of the need to maintain the aldehyde and alcohol product in the vapor phase above the dew point, the reaction pressure may be slightly affected by the reaction temperature, the amount of aldehyde and hydrogen-containing gas to be hydrogenated. The space velocity for the hydrogenation reaction may range from about 0.1 to 2.0 based on the liquid volume of aldehyde fed to the evaporator per volume of catalyst per hour.

Preferably the process of the invention is carried out in a continuous process. In a preferred continuous operation, the aldehyde, the mixture of aldehydes, or the oxo reaction product is evaporated as necessary and carried out with the hydrogen-containing gas at the desired temperature and pressure on the catalyst of the invention. Advantageously the catalyst can be used in a fixed catalyst bed reactor. The reaction zone may be an elongated tubular reactor with a catalyst supported in the tube. It is also possible to use an adiabatic tank type reactor. The heat of reaction in such a reactor increases the reaction temperature from the reactor inlet to the reactor outlet.

The catalyst of the present invention having enhanced selectivity, and especially the catalyst having enhanced selectivity by alkali and transition metal selectivity enhancers, can inhibit the formation of esters at high temperatures and high alcohol concentrations. Thus, adiabatic reactors can be used to their full potential. However, it is also possible to use the catalyst in a cooled tube in a fixed bed of catalyst or in an isothermal or near isothermal reactor containing the catalyst in a cooling tube. As noted above, when the entire catalyst layer is used close to its maximum temperature, excellent selectivity can be obtained even with the catalyst of the present invention. Under these conditions, the heat of reaction can be recovered as useful energy, for example by generating high pressure steam.

The alcohol product recovered from the hydrogenation reaction is condensed to separate from unreacted hydrogen, and excess hydrogen is again compressed to recycle to the reaction zone.

The following examples illustrate the invention and are not intended to limit the scope of the invention as defined in the appended claims.

[Catalyst Preparation Method]

A solution (16 L) containing 417 g of copper marketed as copper nitrate and 858 g of zinc marketed as zinc nitrate is heated to about 110 ° F., sprayed with 15.7% by weight sodium carbonate solution (12.75 L) and then mechanically stirred And then maintained at about 140 ° F. The final pH of the precipitation mixture is about 7.0 to 8.5. After precipitation, the copper-zinc basic carbonate is washed and about 80% of the filtrate is decanted to remove sodium. Washing four times with 100-120 ° F. wash water and decanting reduced the sodium capacity in the calcined filter cake to about 0.1-0.15% by weight. The copper-zinc basic carbonate precipitate is calcined to obtain a mixture of copper oxide and zinc oxide (catalyst precursor composition). Then a sufficient amount of catalyst to provide a calcined catalyst composition of about 0.7 wt% potassium oxide, 3.0 wt% nickel oxide, 2.0 wt% graphite, 32.0 wt% copper oxide, and 62.3 wt% zinc oxide The aqueous slurry (30 wt% solids) of the precursor, graphite, nickel nitrate and potassium nitrate is spray dried. The spray dried powder is compressed and then calcined at 700 ° F. to decompose the nitrate. Reduction then yields a catalyst according to the invention.

Example 1

The mixed butyraldehyde containing 1 part isobutyraldehyde and 9 parts n-butyraldehyde, as obtained by hydroformylation of propylene at low pressure over a rhodium-containing catalyst, is divided into equal fractions, and then each Two Stage Insulation Experiment In a plant-scale hydrogenation reactor system, the reactor is fed at a space velocity of 0.8 (total liquid feed capacity for the total capacity of catalyst per hour). A gas feed containing 60% hydrogen and 40% nitrogen is fed to the inlet of the first reactor with a molar ratio of hydrogen to aldehyde of 13: 1. The gas effluent from the first reactor is mixed with the second portion of the mixed butyraldehyde feed and then passed through to the second reactor in succession. The pressure at the outlet of the second reactor is maintained at 100 psig. The vaporized aldehyde and hydrogen mixture is fed at 125 to the first reactor, which is discharged into the reactor at a temperature of 210 ° C. After further addition of the aldehyde, the effluent from the first reactor is adjusted to 128 ° C. at the inlet of the second reactor and discharged to the second reactor at a temperature of 196 ° C. The catalysts in both reactors were about 33 weight percent copper oxide and about 67 impregnated with about 3 weight percent nickel oxide (about 2.4 weight percent nickel) and about 1 weight percent potassium carbonate (about 0.6 weight percent potassium). Prepared by reducing the calcined catalyst precursor composition consisting essentially of weight percent zinc oxide. The calcined precursor catalyst composition is reduced using a nitrogen-containing dilute hydrogen stream as diluent at a temperature of about 200 ° C. The mixed butanol product, condensed from the outlet of the second reactor, contains only 1.6 wt% unreacted aldehyde and only 0.05 wt% mixed iso- and n-butyl butyrate.

Example 2

In a control example for example 1, except that the catalyst is an unmodified, reduced copper oxide-zinc oxide catalyst (a precursor catalyst of about 33 wt% copper oxide and about 67 wt% zinc oxide) The experiment is carried out under similar reaction conditions in the same experimental plant as described in 1. The product condensed from the outlet of the second reactor containing 0.3% aldehyde and 2.9% mixed butyl butyrate indicates a significant increase in the production of ester byproducts. In another experiment with a peak temperature of 188 ° C., a product sample containing 1.9% unreacted aldehyde and 1.2% butyl butyrate is recovered. Both experimental results yield significantly more esters than the esters obtained using the catalyst in Example 1.

Example 3

Propionaldehyde is fed to a steam jacketed tubular reactor (0.5 in diameter x 4 ft in length) enhanced with the catalyst of enhanced selectivity described in Example 1. During the test, the liquid space velocity is maintained at 0.4 hourly, the temperature is nearly isothermal at 150 ° C., the pressure is fixed at 50 psig, and the pure hydrogen as co-reactant is supplied with a molar ratio of hydrogen to propionaldehyde at 20: 1. . The condensed product contains only 0.02 wt% propyl propionate and 0.04 wt% propionaldehyde.

Example 4

Valeraldehyde is fed to a small laboratory tubular reactor operated isothermally at 150 ° C. and 60 psig. The same selectivity enhanced catalyst as used in Example 1 is used. When the aldehyde conversion is 95%, the byproduct pentylpentanoate is produced only 0.08% by weight.

Example 5

In this example, before reduction, essentially consisting of about 33% copper oxide and about 67% zinc oxide catalyst. The effects of various modifications on aldehyde hydrogenation on the calcined precursor catalyst composition are tested. The hydrogenation test is carried out in a set of small laboratory tubular reactors operated under the same conditions. The test results are shown in the following table. Reaction conditions include a pressure of 60 psig, an outlet temperature of 192 ° C., a feed molar ratio of hydrogen 10: butyraldehyde 1, and a space velocity (based on gas effluent under standard conditions) of total gas per hour of catalyst 120 , 000 capacity.

(Butyl ether or propane do not form any significant amount) (1% K ₂ CO ₃ corresponds to 0.6% potassium)

As noted above, the use of nickel, cobalt or potassium enhanced catalysts reduces the production of ester byproducts. Mixtures of potassium and nickel selectivity enhancers are used to obtain significant reduction grades.

Example 6

Compared to reduced copper oxide-zinc oxide catalysts with enhanced selectivity and copper oxide-zinc oxide catalysts without enhanced selectivity in a reactor fed with a mixture of iso- and n-butyraldehydes with a weight ratio of 1:99. Get data at conversion rates higher than%. The peak reaction temperature is about 210 ° C. The inlet conditions are adjusted to obtain a partial pressure of 6 psig for butyraldehyde and a partial pressure of 70 to 77 psig for hydrogen. The total gas phase feed rate is 4800 standard fr ² per ft ^{2 of} catalyst per hour. The results are shown in the following table.

By using only alkali metal selectivity enhancers as in Example 5, the production of byproduct esters is significantly reduced by about 80%, while the mixture of potassium and nickel is an additional feed in a significant reduction.

Example 7

Using the reactor and reaction conditions described in Example 5, the performance of the various copper-containing catalysts was tested (as in the ratios described below, the catalysts tested were substantially free of ester blood volume or other byproduct formation such as ethers). It is not effective in reducing the result of the test.

(Before reducing)

While certain particular embodiments of the present invention have been described, those skilled in the art will recognize various variations of the present invention. Accordingly, the scope of the present invention will be limited only by the appended claims.

Claims (13)

Prepared by reducing the precursor catalyst composition containing copper oxide and zinc oxide, based on the weight of copper oxide and zinc oxide in the precursor catalyst composition, (i) with sodium, potassium, lithium, cesium and mixtures thereof Impregnated with a selectivity enhancer comprising a mixture of about 0.05 to 7.0 weight percent alkali metal selectivity enhancer selected from the group consisting of and (ii) about 0.5 to 5.0 weight percent transition metal selectivity enhancer selected from the group consisting of nickel, cobalt and mixtures thereof. , An aldehyde hydrogenation catalyst composition consisting essentially of a mixture of reduced copper oxide and zinc oxide. The aldehyde hydrogenation catalyst composition of claim 1, wherein the amount of alkali metal selectivity enhancer is about 0.3 to 3.5 weight percent. The aldehyde hydrogenation catalyst composition of claim 1, wherein the alkali metal selectivity enhancer is potassium. The aldehyde hydrogenation catalyst composition of claim 1, wherein the amount of transition metal selectivity enhancer is about 1.0 to 4.0 weight percent. The aldehyde hydrogenation catalyst composition of claim 1, wherein the transition metal selectivity enhancer is nickel. The aldehyde hydrogenation catalyst composition of claim 1, wherein the selectivity enhancer comprises a mixture of (i) about 0.05 to 7.0 weight percent potassium and (ii) about 0.5 to 5.0 weight percent nickel. 7. The aldehyde hydrogenation catalyst composition of claim 6, wherein the selectivity enhancer comprises a mixture of (iii) about 0.3 to 3.5 weight percent potassium and (ii) 1.0 to 4.0 weight percent nickel. (I) about 0.05 to 7.0 weight percent alkali metal selectivity enhancer selected from the group consisting of (i) sodium, potassium, lithium, cesium, and mixtures thereof based on the weight of copper oxide and zinc oxide in the precursor catalyst composition; A precursor aldehyde hydrogenation catalyst composition consisting essentially of a mixture of copper oxide and zinc oxide impregnated with a selectivity enhancer comprising a mixture with about 0.5 to 5.0 weight percent of a transition metal selectivity enhancer selected from the group consisting of nickel, cobalt and mixtures thereof. 9. The precursor aldehyde hydrogenation catalyst composition of claim 8, wherein the amount of alkali metal selectivity enhancer is from about 0.3 to 3.5 weight percent. 9. The precursor aldehyde hydrogenation catalyst composition of claim 8, wherein the selectivity enhancer is potassium. 9. The precursor aldehyde hydrogenation catalyst composition of claim 8, wherein the amount of transition metal selectivity enhancer is about 1.0 to 4.0 weight percent. 9. The precursor aldehyde hydrogenation catalyst composition of claim 8, wherein the transition metal selectivity enhancer is nickel. 9. The precursor aldehyde hydrogenation catalyst composition of claim 8, wherein the selectivity enhancer comprises a mixture of (i) about 0.05 to 7.0 weight percent potassium and (ii) about 0.5 to 5.0 weight percent nickel.