DD295096A5 - PROCESS FOR PREPARING A CATALYST FOR GLUCOSE HYDROGENATION - Google Patents

Abstract

The invention relates to a process for the preparation of nickel carrier catalysts for the hydrogenation of glucose to sorbitol in the fixed bed process. The aim is to obtain a cheap, active and economical catalyst with good long-term hydration properties. The object is achieved by nickel nickel nitrate solution being precipitated in a soda-silica solution having a silicon / carbonate ratio of 0.45 to 0.56, and precipitating further nickel depending on the amount of nickel extractable from the ethylenediamine precipitate. A calculation rule for the additional amount of nickel to be precipitated is given. {Nickel Catalysts; hydrogenation; glucose; sorbitol; Silicon / carbonate-Relations; Ethylendiaminextraktion; Calculation; Nickel addition}

Description

Ni ₂₁₁ , = (XXS - EXS) / (E + 189 - X) - Ni _verb

in the formula "E" of the extractable by ethylenediamine from the solid of the precipitation suspension nickel content, calculated in % of the nickel contained altogether in the solid after precipitation, "S", the amount of SiOj, "Ni _V ert>" up to neutralize spent nickel amount "Ni _2U5" additionally conclusively verfällende amount of nickel and "X" used in the precipitation represent a size with values between 155 and 170.

2. The method according to claim 1, characterized in that the molar ratio silicon / carbonate ions in the soda-silicate solution is 0.48 to 0.52.

3. The method according to claim 1 and 2, characterized in that the silicate concentration, calculated as SiO ₂ in the soda-silicate solution is 10.5 to 12 g SiO ₂ /).

4. The method according to claim 1 to 3, characterized in that the pH in the soda-silicate solution to 10.8 to 11.3, measured at 293 K, is set.

5. The method according to claim 1 to 4, characterized in that sodium hydroxide solution is used to adjust the pH of the soda-silicate solution.

Field of application of the invention

The invention relates to a process for the preparation of a catalyst for the hydrogenation of glucose to sorbitol in the fixed bed process.

Characteristic of the known solutions

For the hydrogenation of glucose In aqueous solutions, nickel catalysts are predominantly used in the art. In addition to non-reactive Raney nickel catalysts, nickel-supported catalysts are primarily used for this process, in which the active component is present in highly dispersed form and with a high surface area on the support. SIO ₂ (eg diatomaceous earth, silica gel) and Al ₂ O ₃ are frequently mentioned in the literature. Various methods are known for applying the hydrogenation-active nickel to the support. Thus, the carrier can be impregnated with a solution of a nickel salt (eg Ni (NO ₃ I ₂ .6H ₂ O) (DE-OS 1442 530).) However, these catalysts have a relatively low catalytic activity, since the active component in the Course of the further manufacturing process (drying, calcination, reduction) coarsely dispersed enriches the outer surface of the carrier.

In other processes nickel is therefore precipitated on the surface of the support in the form of an insoluble precipitate. For this purpose, the support is suspended in the nickel salt solution and precipitated with a precipitating agent (eg NaOH, Na ₂ CO ₃ , NaHCO ₃ ), then the nickel is precipitated thereon (DE-OS 2016602, DE-OS 1943362, DE-OS 1667194). As carrier in these Fällverfohren natural, porous solids (diatomaceous earth [DE-OS 1667106]) or synthetic porous solids (AI ₂ O ₃ or silica gel [DE-OS 2016603)] is used. The production of nickel catalysts by co-precipitation of active component and carrier has proved to be particularly favorable. Precipitation takes place with a basic precipitant at temperatures of 323 to 363 K (DE-OS 2726710). Furthermore, it is known to replace part of the solid support by water-soluble silicates (DE-OS 2150975). By hardening special precipitation conditions (DD-PS 156168) and by precipitation of a nickel silicate with a Ni / SiO ₂ ratio of 1.5 (DD-PS 206160) as an intermediate, it was tried, the uniformity of the precipitates and the

to improve the catalytic activity of the catalysts prepared therefrom. However, all these methods have in common that catalysts are obtained which are relatively nonuniform and also can not satisfy in terms of their activity and life. Especially when using nickel-supported catalysts for the hydrogenation of glucose to sorbitol with a fixed catalyst, high demands are placed on the activity and in particular on the mechanical stability of the molded articles. Under the conditions of glucose hydrogenation, the support of the catalysts is washed out very quickly. As a result, in the known, relatively inhomogeneous catalysts, a non-uniform change, in particular also the strength of the catalyst moldings, occurs. The consequence of this is unnecessary, very complex catalyst changes, although the catalyst was not exhausted in its activity. After all known manufacturing processes for nickel catalysts, this disadvantage could not be completely eliminated.

Object of the invention

The object of the invention is to develop a process for the preparation of a nickel-supported catalyst for the glucose hydrogenation, which makes it possible to obtain a cheap, active and economical catalyst with good long-term hydration properties.

Explanation of the essence of the invention

The object of the invention is to develop a process for the preparation of a nickel-supported catalyst for the hydrogenation of glucose, which makes it possible to obtain a homogeneous, high-strength fixed-bed catalyst that can be produced, in particular, during deformation with little effort.

This object is achieved by a method for producing nickel-supported catalysts based on the addition of a waterglass solution to a soda solution, uniform metered addition of a nickel nitrate solution, separating the precipitated precatalyst from the precipitation suspension, washing, drying, shaping, reducing and stabilizing the filter cake according to the invention by water solution is added to the soda solution to a molar ratio of silicon to carbonate ions of 0.45 to 0.56, by adding water and basic compounds dissolved therein a pH, measured at 293K, of 10.5 to 11.5 and a Silica concentration, calculated as silicon dioxide, is adjusted from 10 to 12.5 g per liter of solution is added to this solution while stirring nickel nitrate solution evenly until a pH of 7.0 to 8.5 is reached, the solid of the precipitation suspension in terms of Content of by 10g ethylenediamine hydrate per g of solid at room temperature extracted in 20 minutes of extractable nickel, the temperature during the precipitation is 323 to 343K and stirred for 1 to 10 hours, from the measured value of extractable nickel in the solid of the precipitation suspension having the formula:

Ni ₁₁₁ , = (X x S - E x S) / (E + 189 - X) - NU *

in the formula "E" of the extractable by ethylenediamine from the solid of the precipitation suspension nickel content, calculated in % of the nickel contained altogether in the solid after precipitation, "S", the amount of SiO ₂ used in the precipitation, "Ni _v« rt>"up for neutralization consumed amount of nickel, Ni _n ,," additionally conclusively verfällende amount of nickel and .X "represent a size with values between 155 and 170.

It is important for the process according to the invention that the nickel content of the catalyst is determined by the measured value of the extractable nickel. It is favorable if the ratio silicon / carbonate ions is in the range of 0.48 to 0.52. The silicate concentration in the soda-silica solution should preferably be 10.5 to 12 g of Si (VI and the pH preferably 10.8 to 11.3.

The process according to the invention makes it possible to produce very uniform precipitation products and thus lays the foundation for the production of highly effective catalysts. By using the optimal, actually effective Aktivkompenentenmengen succeeds in reducing the cost of catalyst production. The catalysts prepared according to the invention are resistant to the glucose solution used and are thus characterized by a longer service life.

Ausführungsbelsplel Example 1 (Compilation Bullet)

As disclosed in DD-PS 217996, a catalyst was prepared by impregnating an AljOa support with a solution containing phosphate ions and the amine complex compounds of nickel and copper, followed by drying, reducing and stabilizing. The A ^ Oa support consisted of strands about 1 mm in diameter and had a BET surface area of 245 mVg, a pore volume of 0.76 cmVg and an outer surface area of 1.1 mVl. The finished catalyst had a bulk density of 0.58 kg / l.

Example 2 (Vergelelchsbeleplel)

6:61 of a sodium silicate solution with an SiO ₂ content of 45 g / l were added to the pinned soda solution (2.5 kg of soda in 6 l of water) with vigorous stirring over the course of 30 minutes. Subsequently, 31 of a nickel nitrate solution having a nickel content of 150 g / l were metered in at a rate of 1.51 / h. The temperature during the precipitation was 333K. The suspension was then stirred for 1 hour. Thereafter, another 3.51 of the nickel nitrate solution was passed into the precipitation suspension within 2 hours.

The resulting precipitate was washed with water to remove unwanted components (eg sodium and nitrate ions), dried at 423 K for 10 h, then pressed into cylindrical molds having a bursting pressure of 45 MPa, then reduced in hydrogen flow at 723 K, the hydrogen at the temperature Desorbed in a nitrogen stream and the catalyst after cooling to 353K in a nitrogen stream with an oxygen content of 1 vol .-% stabilized. The catalyst had a nickel content of 65.8%, a bulk density of 1.11 kg / l and, after reduction and stabilization, a bursting pressure of 13.5 MPa.

Example 3 (comparative example)

To a soda solution was added sodium silicate solution, water and sodium hydroxide solution until a concentration of silicate, calculated as SiO ₂ , of 3.9 g per l, a silicon / carbonate ion ratio of 0.255 and a pH of 11.2, measured at 293 K, were set. Subsequently, a nickel nitrate solution having a nickel content of 160 g / l was uniformly metered to the soda / silicate solution until a pH of 7.4, measured at 293 K, was reached. The temperature during the precipitation was 333K. From the precipitation suspension, a sample of the precipitate was taken and washed. About 2 g of the solid was suspended in 150 ml of water, 20 g of ethylene hydrate added and stirred at 298 K for 20 minutes. The precipitate was separated from this suspension and the nickel content was determined both in the solid and in the solution. From the values obtained, the proportion of nickel in the solid of the precipitation suspension was calculated, which can be extracted by ethylenediamine. Dor determined extractable content .E * was used for the calculation of the additional nickel content .Ni _n ,, 'required for the catalyst. "E" was used in the equation Nl _n ,. = (S χ 200-S χ E) / (E-11) - Ni «* In this equation," S "corresponds to the silicate used in the soda-silicate solution , calculated as SiO ₂ from the volume of the solution multiplied by the silicate content. The value of the quantity of nickel consumed to calibrate the pH value of 7.4, "Niv, _rb ", is calculated from the volume of nickel nitrate solution already used multiplied by the nickel content of the solution (160 g Ni / I) amount of nickel to be precipitated was metered in the form of nickel nitrate solution simultaneously with the soda solution required to maintain the pH in the range of 7 to 8.5 in the precipitation suspension already stirred for 3 to 343 K. The precipitate formed was used to remove unwanted constituents (e.g. After drying, the catalyst was compressed into cylindrical Forrr'.ingen having a bursting pressure of 55 MPa, and further processed as in Example 2. After stabilization, the catalyst had been pressed Catalyst a bursting pressure of 8.5 MPa and a bulk density of 1.15 kg / l.

Example 4 (Inventive example)

To a soda solution, sodium silicate solution, water and sodium hydroxide solution were added until a concentration of silicate, calculated as SiO ₂ , of 10.5 g / l, a silicon / carbonate ion ratio of 0.52 and a pH of 11.1, were measured at 293 K, were set. Subsequently, a nickel nitrate solution having a nickel content of 160 g / l was uniformly metered to the soda-silicate solution until a pH of 7.8, measured at 293 K ₁ , was reached. The temperature during the precipitation was 333 K. From the precipitation suspension, a sample of the precipitate was removed and washed. About 2 g of the solid was suspended in 150 ml of water, 20 g of ethylenediamine hydrate added and stirred at 298K for 20 minutes. The precipitate was separated from this suspension and the nickel content was determined both in the solid and in the solution. From the values obtained, the nickel content in the solid of the precipitation suspension was calculated, which can be extracted by ethylenediamine eich. The determined extractable nickel content, E "was used for the calculation of the additional nickel content, Ni _n , required for the catalyst according to the invention. In the equation, Ni _11n (S x 162 - S χ E) / (E + 27) - NU * is used. In this equation, "S" corresponds to the silicate used in the soda-silicate solution, calculated as SiO ₂ from the volume of the solution multiplied by the silicate content. The value of the quantity of nickel consumed to reach the pH value of 7, "Niv.rb" /, is calculated from the volume of nickel nitrate solution already used multiplied by the nickel content of the solution (160gNi / l), thus calculating the amount of nickel to be precipitated In the form of nickel nitrate solution, simultaneously with the soda solution required to obtain the pH in the range of 7.0 to 8.5, was metered into the precipitation suspension which had already been stirred for 3 hours at 343 K. The further processing was carried out as indicated in Examples 2 and 3 Catalyst was compressed after drying at a bursting pressure of 14 MPa. The final catalyst after reduction had a bursting pressure of 9 MPa and a bulk density of 0.94 kg / l.

The catalysts from Examples 1-4 were tested catalytically under the test conditions mentioned. In each case 300 ml of the catalysts were heated in a high-pressure apparatus in the hydrogen stream of 900 l / h within 15 hours to 443 K and left for 5 hours at this temperature. After cooling to 383 K and rinsing the high pressure reactor with water under 25 MPa hydrogen pressure, an aqueous solution of glucocarbonate was hydrogenated under the following conditions: pressure 25 MPa, temperature 383K, 2000 standard liters hydrogen passage / h, concentration of glucose solution 50%, loading with glucose solution 500 g / h. Table 1 summarizes the results obtained.

Table 1

catalyst Sales of glucose (%) Sorbitol selectivity (%) example 1 74.3 72.6 (Comparative Example) example 88.9 85.3 (Comparative Example) Example 3 98.1 93.8 (Comparative Example) Example 4 99.8 97.2 (Invention)

-4- 235

In a further experiment, starting at 383 K, the reaction temperature was increased by 5 Qrad, falling below a Qiucoseumatzes of 99.8% until a reaction temperature of 418K was reached. The consumption of catalyst was determined from the amount of glucose hydrogenated up to this point in time and the catalyst backbone used. Table 2 summarizes the results.

Table 2 Catalyst catalyst consumption (g / kg 50% solution)

Example 1 9.2

(Comparative Example)

Example 2 6.7

(Comparative Example)

Example 3 3.1

(Comparative Example)

Example 4 1.1

(Invention)

Tables 1 and 2 clearly show the better results of the catalyst according to the invention according to Example 4. The bursting pressures determined according to the catalytic test (Table 3) also prove the superiority of the catalyst according to the invention.

Table 3

catalyst Bursting pressure (MPa) to Difference (MPa) in front - example 1 - _ (Comparative Example) Example 2 13.5 partial decay (Comparative Example) 3.5 Example 3 8.5 5.0 (Comparative Example) 7.0 Example 4 9.0 2.0 (Invention)

Claims (1)

1. A process for the preparation of nickel-supported catalysts for the hydrogenation of glucose to sorbitol on the basis of the addition of a waterglass solution to a soda solution, uniform addition of a nickel nitrate solution, separation of the precipitated precatalyst from the precipitation suspension, washing, drying, shaping, reducing and stabilizing the filter cake, characterized in that water glass solution is added to the soda solution to a molar ratio of silicon to carbonate ions of 0.45 to 0.56, by addition of water and basic compounds dissolved therein, a pH, measured at 293K, from 10.5 to 11.5 and a silicate concentration, calculated as silica, from 10 to 12.5 g / liter solution is added to this solution while stirring nickel nitrate solution is uniformly added until a pH of 7 to 8.5 is reached, the solid the precipitation suspension with respect to the content of 10 g Ethylenendiaminhydrat per g of solid at Raumt emperature is examined in 20 minutes of extractable nickel, the temperature during the precipitation is set to 323 to 343 K and stirred for 1 to 10 hours from the measured value of extractable nickel in the solid of the precipitation suspension having the formula