DE2150975A1 - Nickel silica hydrogenation catalyst - of high specific surface,low alkali content for hydrogenating aldehydes,olefins - Google Patents

Abstract

Nickel-silica hydrogenation catalyst (e.g. for fully hydrogenating 2-20C olefins, 6-20C aromatic hydrocarbons, or 1-20C aldehydes) has a Na content 0.2 wt% in which the nickel has a specific surface >70 m2/g. Catalyst pref. contains 25-50 wt% Ni, silica-support is pref. kieselguhr or diatomaceous earth (10-70 wt% of total silica).

Description

Nickel-silicon dioxide catalysts are the subject of the invention highly active nickel-silica catalysts with stabilized high nickel surface areas. The invention particularly relates to supported nickel-silica catalysts which contain very small amounts of alkali metals. These nickel-silica supported catalysts show in the hydrogenation of organic substrates compared to catalysts with lower nickel surface areas and relatively high concentrations of the active catalyst on alkali metals improved activity.

Nickel-silica catalysts supported on porous silica particles, such as kieselguhr, infusor earth, diatomaceous earth or silica containing alumina are known and have been widely used for hydrogenation reactions. Typical Hadration reactions are e.g.

the hydrogenation of olefins to saturated hydrocarbons, the Hydrogenation of aromatics, such as benzene, and conversion of oxoaldehydes and the like. To the corresponding alcohols. Until now, however, it has been limited because of the Activity of the known nickel catalysts and the fact that these catalysts Deactivated @erden fairly quickly, not a completely satisfactory seduction for these hydration reactions developed.

Studies have shown that the activity of the catalysts is directly related to the nickel surface area and the catalysts be deactivated more quickly if the nickel surface area is reduced.

This means that catalysts with a high nickel surface area have a higher Activity and a long catalyst life.

In U.S. Patent 3,351,566 a nickel-silica catalyst is used described, the nickel surface area of which is significantly larger than that of the known Catalysts. Surface areas of between 45 and 60 m² / g are specified. The nickel surface area is defined as the area per unit weight of nickel or expressed per unit weight of the total catalyst (m² / g). Are present all nickel surface areas on the @asis area per unit weight of the total Specified catalyst.

According to the invention it was surprisingly found that under Use of carefully controlled critical conditions in the manufacture of the Catalyst produce a supported nickel catalyst on proous solid particles having a nickel surface area of above about 70 m² / g, preferably of 75-100 m² / g and has a catalytic hydrogenation activity that is several hours is greater than that of the known nickel catalysts.

According to the invention, the hydrogenation of organic compounds is in general significantly improved if you use the hydrogenation in the counter @ kind of a nickel-silicon dioxide Catalyst with a nickel surface area of over 70 m2 / g of the active catalyst and an alkali metal content of less than 0.2% by weight.

According to a preferred embodiment of the invention, the hydrogenation organic compounds with multiple chemical bonds in the presence of a nickel-silicon dioxide Catalyst with a nickel surface area of from about 75 to about 100 m² / g, one Total surface area from about 225 to about 300 m² / g and a sodium content of about 0.1 wt.% or less, based on the total weight of the active catalyst, causes.

The preparation of the catalyst according to the invention requires the use separate solutions, which are preferably aqueous. In a first solution will a source for silicate anions, in a second solution a source for nickel cations solved. A porous carrier is suspended in the solution containing the silicate anions, preferably a porous silica support such as kieselguhr. The two solutions are mixed, preferably by adding the nickel-containing solution to the Silicate solution within about 5-40 minutes. By mixing the two together previously prepared solutions will be the amount of dissolved nickel in the reaction mixture kept extremely low, generally well below 0.60 moles / l of aqueous Mixture. This dilution of the dissolved nickel ions is necessary for the production of catalysts with high nickel surface area is essential. Also should the addition with essentially constant speed with vigorous mixing orfol @ en, so that a possible more even Katalyeator is formed. The mixture is then on heated to its boiling point and a precipitant added to remove the dissolved silicate and to precipitate nickel ions on the porous carrier. A preferred precipitant is NH4HCO3. Alkali metal bicarbonates, hydroxides and oxides represent because of the likelihood that some alkali metal is ultimately incorporated into the finished catalyst, in the are generally not desirable precipitants for this process.

During manufacture, water is added by evaporation to continuously replace lost water and thus an almost constant one Maintain volume. The aqueous mixture will be at its boiling point for 1-5 hours held, then filtered and the product obtained repeatedly with boiling water washed. Then the catalyst is dried, calcined under oxygen and activated. The activation process consists in adding the catalyst a gaseous reducing agent, usually a stream of hydrogen brings.

As already stated, the solution containing nickel and the Silicate-containing solution mixed under dilution conditions, so that the amount of the dissolved nickel ions in the resulting aqueous mixture is extremely low and thereby a catalyst with a high nickel surface area is obtained will. In addition, it is essential in the preparation of the catalyst according to the invention, that the precipitation of the catalyst takes place from dilute solutions, i.e. the nickel containing solution must have a nickel concentration of not more than 1.0 mole / l and the Solution containing silicate must have an alkali metal silicate concentration of not more than 0.40 moles / l. Most preferred are solutions that are no more than 0.75 Contains moles / l gusset and 0.26 llole / l sodium metasilicate. This precipitation differs differs from the precipitation of a more concentrated solution, in which the solution is used up to twice contains as much dissolved substance.

About 30-90% by weight of the total silica content of the activated Catalyst come from the precipitated silicate ions. Preferably, however, come 50-70% by weight of the total silica content of the silicate ions. The applied The nickel: silicate molar ratio is then typically about 0.75: 1 to about 1.75: 1.

The bleaching stages in the manufacture and activation of the catalyst are identical to those described above.

Use of the dilute solution gives a catalyst with im essentially the sign of itickel surface area, but a considerably larger one Catalyst activity. In fact, for example, in the hydrogenation of benzyl, the activity increased by a factor of about 2.

Although the processes in the inventive method do not adhere to a specific one To be bound by theory, one assumes d the use of the additional Solvent, i.e. of water the concentration of alkali metal ions in the solution decreased so that less alkali metal, e.g.

Sodium can be introduced into the precipitated crystallites. In any case, studies have shown that the3 repeated washing of the nickel-silica Catalysts do not reduce the alkali metal content of these catalysts and thereby their activity increased. only if solutions diluted in the manner described above are used, one obtains highly active catalysts that contain little sodium.

More specifically, the present invention relates to manufacture an improved hydrogenation catalyst. It can be used for the hydrogenation of aromatics, e.g. for the hydrogenation of benzene to cyclohexane, for the hydrogenation of saturated and unsaturated aldehydes to alcohols, as in the known oxo process, for hydrogenation of the double bonds in edible fats and oils as well as of other straight-chain and branched olefins and used for the hydrogenation of nitro compounds to amines will. The term "olefins" means unsaturated compounds with at least one multiple bond and comprises polyunsaturated compounds.

only the production of the catalyst, the nickel and silicate ions together on a porous solid carrier in Geilch-en form, preferably a porous particulate silica support. First, two specific solutions are made.

One of these solutions contains a source of silicate ions, such as alkali silicates, @.H. Sodium and Potassium Silicates, Sodium Metasilicate, etc., Silica or Hydrolyzed Silicone hydride.

The amount of the silicate anion in this solution is about 1-3Og / l, preferably 10-20 g / l. The solution can be at atmospheric pressure and room temperature being held.

The second solution contains a source of nickel cations.

It can consist of nickel nitrate, nickel chloride or nickel bromide. The nickel concentration of this solution is 5-60 g nickel / l, preferably 30-45 g / l.

Other sources of nickel cations known to those skilled in the art can also be used and silicate anions can be used.

The porous solid particles, preferably silica particles, are suspended in the solution containing the silicate anions. As porous particles are in particular kieselguhr, infusor earth, diatomaceous earth, containing trickle acid Earth, silicon dioxide or aluminum oxide are suitable. The concentration of the porous Solid particles can be expressed as a percentage of the total silica in the catalyst and should be 10-70, preferably 30-50 wt. be.

The two solutions become one another at low speed given to achieve maximum mixing effect. Typically, a Nickel nitrate solution evenly within about 5-40 minutes, preferably by Added to a sodium metasilicate solution for 10-30 minutes. After mixing the Both solutions must complete the joint precipitation of the nickel and silicate ions will. This can be accomplished by various known methods. Most convenient if you complete the joint precipitation of the nickel and silicate cations in the aqueous, the solution containing the solid carrier particles by adding a solution which is soluble in water alkaline precipitants such as ammonium bicarbonate. The solution should then be around their boiling point are heated. Alkaline ammonium precipitants are for the reduction the amount of alkali metal residues required to avoid a poisoning effect must be removed from the finished catalyst by washing, most suitably. In some cases, potassium precipitants can be used when the potassium is considered Accelerating, not acting as a poisonous agent.

The preferred metal salts are the water-soluble compounds, z .. the nitrates, formates or oxalates are used. The preferred catalytic metal is nickel, however, other catalytic metals can also be used will. These metals include cobalt and iron.

After precipitation, the mixture will boil for about 1-5 hours held. Then it is filtered and washed four times with boiling water. Of the precipitated catalyst is then heated to 90-205 ° C for about 15 hours dried. It is then heated for 2-8 hours, preferably 3-5 hours in the presence of an oxygen-containing gas or air to a temperature Calcined from 315 to 4800 C.

When the calcination is finished, the catalyst must be activated be reduced. The heduction is carried out in the presence of a reducing gas, preferably Hydrogen carried out. The hydrogen is at room temperature at a rate from 5 l / h / g catalyst to 100 l / h / g catalyst, preferably from 10 l / h / g Catalyst up to 30 l / h / g catalyst passed over the catalyst. Then it will be the temperature at a rate of about 5.5 ° C / min. increased to 315-480 ° C. This temperature and the flow of hydrogen will be about 1-4 hours, preferably sustained for more than 2 hours.

The reduction is either discontinuous or continuous carried out, preferably after placing the catalyst in a suitable reactor has given. Reactors for this purpose are known.

At this point the catalyst is sensitive to deactivation and can at ordinary temperatures in the presence of oxygen without prior Passivation cannot be stored. The passivation can consist in that one the reactor at a temperature of over 1500 C with an inert Gas, preferably nitrogen flushed, cooled to room temperature and then that inert gas passes over the catalyst, air in such an amount in the inert Introduces gas such that there is about 1-2 mole percent oxygen. Through this procedure the catalyst receives a surface coating of oxide and is passivated.

The obtained catalyst has a nickel surface area in a reduced state from 70-100 m² / g and a total surface area of 150-300 m² / g. The catalyst contains also about 0.1 wt. or less sodium and 25 to about 50 wt.% nickel. This Catalyst is extremely effective in the hydrogenation of olefins (this one Term includes diolefins and similar compounds), aromatics, saturated and unsaturated aldehydes, in the oxo process, in the hydrogenation of edible fats and oils, from nitro compounds to amines, preferably in the hydrogenation of straight chain and C2-C20 branched olefins, 06-020 aromatics, including condensed non-aromatics and C1-C20 aldehydes.

The catalyst according to the invention is particularly useful in Hydrogenation of benzene to cyclohexane. In the presence of a nickel-silicon dioxide catalyst with a content of less than 0.2% by weight of sodium and preferably 0.1% by weight / or less sodium in the active catalyst will give significantly improved results.

The conditions for the indicated hydrogenation reactions vary strong and known to those skilled in the art. In general, the following conditions can apply applied: temperature 65-540 ° C; Pressure 1 atmosphere to 840 atmospheres overpressure; Feed rate 0.2-100 parts by volume / hour / parts by volume; Hydrogen supply 355-1780 m3 / m3.

In the Oxo process, carbon monoxide and hydrogen are added to AlLene, about alcohols, aldehydes and other organic compounds with oxygen functions to obtain. Typical alkenes that can be used in this process are those with 2-20 carbon atoms. Conditions for the oxo reaction are temperatures from 65-175 ° C, hydrogen to hydrocarbon molar ratios of 0.5-10.0 and Pressures from 7.0-70 atm.

The product of such a carbonylation reaction generally consists from aldehydes, acetals, compounds containing unsaturated oxygen and The like. That a hydrogenating treatment in a second or further hydrogenation stage require. The present invention is particularly applicable to the Aldehyde product suitable.

The hydrogenation conditions in this further stage correspond to conditions generally applied in the first stage, example 1 (comparative example) In all examples, the nickel surface area of the catalyst was chemisorbed of hydrogen on the reduced catalyst surface at room temperature in one conventional gas adsorption vacuum system.

This method is extensively described by Yates, Laylor, and Sinfelt in J. At the. Chem. Soc. 86, p. 2996 (1964).

In this example, a catalyst was used with a nickel surface area of 90 m² / g and 0.2 wt.% sodium.

The catalyst was prepared as follows: 1125 g of Ni (NO) 2.6H20 were added 6H2O was added to 2.25 l of water, then 380 g of Ta2SiO3.9H20 to 2.25 l of water. To the second solution, 50 g of diatomaceous earth was added while maintaining a suspension stirred well. The salts were added to the water at room temperature and stirred until they dissolved. It was made with an electric stirrer stirred at a speed of 600 rpm. The addition was made in a standard laboratory device. The nickel solution then uniformly became the sodium silicate solution in about 15 minutes given. During this time the sodium silicate solution was stirred vigorously. Afterward the mixture was heated to its boiling point. At the boiling point of the mixture were 800 g of NH4HCO3 were added uniformly within about 15 minutes. During this Operation lost water through evaporation. About the lost water water was added to replace it. After all of the NH4HCO3 had been added, the Mixture stirred for 3 hours at its boiling point. That which is lost through evaporation Water was replaced again. It was then filtered and the solid fraction with five times washed in boiling water.

Each washing solution consisted of 2 liters of water. Last was the solid catalyst dried at 930 C, calcined for 4 hours in air at 4000 C and several hours Treatment with a stream of hydrogen at about 3540 C activated. It was about 395 g of catalyst recovered.

The obtained catalyst had a nickel surface area of 90 m2 / g and contained 0.2% by weight of fltrium.

Example 2 (Comparative Example) A sample of that prepared in Example 1 KE talysators were used in a continuously operating hydrogenation reactor to the Used to convert benzene to cyclohexane.

The test conditions were: temperature 100 ° C; Space velocity 25 parts by weight / hour / parts by weight; Pressure 1 atmosphere; Hydrogen to hydrocarbon Molar ratio 40.

Under these conditions there was 36.6 Vo of the benzene in cyclohexane converted. The conversion was determined by gas chromatography.

Example 3 (comparative example) About 750 g Ni (iN03) 2.6H2O and 320 g Na25i03.9H20 were together to 50 g of kieselguhr suspended in 3.5 l of water given. The solution was mixed, heated to its boiling point, and then with 800 g ammonium carbonate added. When the precipitation ended, the slurry became heated to boiling for a further 3 hours. The resulting slurry was then filtered, washed, dried and calcined as described in Example 1. It was about 270 g of catalyst recovered. The resulting catalyst had a 2 nickel surface area of 47 m2 / g. This range was determined in the same way as in Example 1.

This example shows that using a single solution instead of the separate solutions of Example 1 a catalyst with a much smaller surface area, i.e. from 90 to 47 m2 / g.

Example 4 (Comparative Example) In this example, the same became Conditions used as in Example 2, but instead of the catalyst -of Example 1, the catalyst according to Example 3 used.

This means that a catalyst was used in the manufacture of which all Components put directly into a solution and not as in the procedure of the example 1 separate solutions were mixed. The conditions for the Benzene hydrogenation was the same as in Example 2. Conversion to cyclohexane was only 18 ,, as determined by gas chromatography.

This example shows that the catalyst of Example 3 with a The hydrogenation catalyst is correspondingly less effective with a lower surface area is used as the catalyst of Example 1.

Example 5 (according to the invention) The production took place in this example of the catalyst with the following deviations as in Example 1: The one for the two Solutions total amount of sser used was twice that in Example 1. I.e., the nickel nitrate and the sodium metasilicate were each in 5 l of water solved. About 395 grams of catalyst were recovered.

The obtained catalyst had a nickel surface area of about 90 m² / g and contained only about 0.1% by weight iiatrinin. I.e. further dilution had no effect on the surface area of the active catalyst, but it did by doubling the amount of solvent the sodium content is halved reduced.

Example 6 (according to the invention) In this example, exactly the same results Conditions as in Example 2 were used, but instead of the catalyst of Example 1, the catalyst of Example 5 is used. The conversion was 62.8. This is an improvement by a factor of 2 compared to the catalyst of the Example 1 and an improvement by a factor of 4 over the catalyst of the example 3. I.e. by further separation of the solutions, a larger catalyst can be used tt achieve.

Example 7 (according to the invention) A sample of the catalyst according to example 5 was,; e-etj sated and used to convert 2-ethylhexanal into the Alcohol used. The test conditions were: temperature 1350 ag space velocity 3.0 parts by weight / parts by weight / hour; Pressure 35 atm; Hydrogen to carbon dioxide Molar ratio 2.5. After 15 hours, 96.0% of the aldehyde had been converted into the alcohol, while in an experiment carried out under identical conditions using a commercially available nickel catalyst was carried out, only 70.1% of the aldehyde were reduced.

This shows a substantial improvement in the conversion of oxoaldehydes to alcohols due to the greater activity of the catalyst according to the invention.

Claims (15)

Claims 1. Nickel-silica catalyst with a nickel surface area of more than about 70 m2 / g of the catalyst and a sodium content of less than 0.2% by weight. 2. Catalyst according to claim 1, characterized in that it has a Has a total surface area of over about 225 m2 / g. 3. Catalyst according to claim 1, characterized in that it is used as Carrier containing porous silica, nickel surface area of 75 m2 / g to 100 m2 / g, a Mickel content of about 25% by weight to about 50% by weight, based on is the total weight of the catalyst, and has a sodium content of about 0.1% by weight. 4. Catalyst according to claim 3, characterized in that the silicon dioxide carrier consists of kieselguhr or diatomaceous earth and about 10% by weight to about 70% by weight of the total silica i.'Ya catalyst makes up. 5. catalyst according to claim 3, characterized in that the silicon dioxide carrier consists of kieselguhr and 30 Gew.i to 50 wt.% of the total silicon dioxide in the catalytic converter. 6. Process for the preparation of the nickel-silica catalyst according to claims 1-5, characterized in that a) it is prepared as an aqueous solution, which contains below about 30 g / l silicate ions b) porous silica particles slurried in the solution prepared in step a) c) a produces aqueous solution that contains less than 6G g / l nickel ions d) the in Step c) the prepared solution at a substantially uniform rate the slurry prepared in step b) and e) the solids obtained calcined. 7. The method according to claim 6, characterized in that the solution of stage a) about 10 to about 20 grams of sodium metasilicate-derived silicate anions and the solution of step c) about 30 to about 45 g / l of nickel nitrate derived Contains nickel ions. 8. The method according to claim 6, characterized in that the Mixture of stage d) heated to its boiling point and added to the heated mixture Ammonium bicarbonate gives. 9. The method according to claim 6, characterized in that the Activated calcined solids by keeping them at a temperature of about 315 Bringing into contact with hydrogen up to about 4800 C. 10. Process for the hydrogenation of organic compounds, characterized in that that the organic compounds in the presence of a nickel-silicon dioxide catalyst with a nickel surface area in excess of about 70 m² / g and a sodium content of less than 0.2% by weight, based on the total weight of the catalyst, with hydrogen brings in contact. 11. The method according to claim 10, characterized in that the nickel-silicon dioxide Catalyst has a nickel surface area from 75 m2 / g to 100 m2 / g and a sodium content of 0.1% by weight, based on the total weight of the catalyst, Has. 12. The method according to claim 1G, characterized in that the catalyst has a total surface area of over 225 m2 / g. 13. The method according to claim 10, characterized in that the organic Compounds of olefins with 2 to 20 carbon atoms, aromatic hydrocarbons with 6-20 carbon atoms or aldehydes with 1 to 20 carbon atoms. 14. The method according to claim 13, characterized in that one is benzene in the presence of a nickel-silicon dioxide catalyst containing 0.1% by weight of sodium, at a temperature of about 65 to about 5400 C and a pressure of 1 atmosphere Hydrogenated to cyclohexane up to 840 atmospheres pressure. 15. The method according to claim 13, characterized in that one Aldehyde product from an oxo reaction in the presence of a nickel-silicon dioxide catalyst, which contains 0.1 wt% sodium, at a temperature of about 65 to about 1500 C and a pressure of about 0.7 to about 70 atmospheres are hydrogenated to the corresponding alcohols.