Catalytic reactor

Abstract

A catalytic reactor for industrial-scale hydrogenation processes is described. The catalytic reactor contains a catalytic fixed bed that comprises a support structure and a catalyst. During operation of the reaction in the catalytic reactor, the fixed bed is filled with reaction medium to at least 85% by volume. A very high contact area of the catalyst with the reaction medium is at the same time provided. The support structure is formed from material webs having a thickness of 5 to 25 μm, with a crosslinking density of at least 3 mm.sup.−3 present. The support structure consists of metals selected from elements of groups 8, 6 and 11 of the periodic table of the elements and mixtures thereof.

Claims

1. A catalytic reactor, comprising a catalytic fixed bed having a volume of 0.5 to 100 m.sup.3, a support structure and a catalyst, wherein, during a reaction, the catalytic fixed bed is filled with a reaction medium to at least 85% by volume and the contact area of the catalyst with the reaction medium is at least 2000 m.sup.2 per m.sup.3 volume of the catalytic fixed bed; and wherein: a) the support structure is formed from material webs having a thickness of 5 to 25 μm, with a crosslinking density of at least 3 mm.sup.−3 present; b) the support structure consists of metals selected from elements of groups 8, 6 and 11 of the periodic table of the elements and mixtures thereof; c) the support structure is catalytically inert to hydrogenation reactions under the reaction conditions prevailing in the catalytic reactor and serves as a support body for a catalyst that is applied to the support structure in the form of a catalytically active coating.

2. The catalytic reactor of claim 1, wherein the proportion of the catalyst applied to the support structure through coating is 2 to 500 kg per m.sup.3 volume of the catalytic fixed bed.

3. The catalytic reactor of claim 2, wherein the catalyst comprises: 60% to 99.8% by weight of support oxides and 0.2% to 10% by weight of catalytically active components, wherein the percentages are, in each case, based on the total amount of catalytic coating forming the catalyst.

4. The catalytic reactor of claim 3, wherein the catalyst further comprises additives and/or functional components.

5. The catalytic reactor of claim 3, wherein the support oxides are selected from the group consisting of: aluminium oxide; silicon dioxide; titanium oxide; and mixtures thereof.

6. The catalytic reactor of claim 3, wherein the catalytically active components are selected from the group consisting of: iron; ruthenium; osmium; cobalt; rhodium; iridium; nickel; palladium; platinum; copper; silver; gold; and mixtures thereof.

7. The catalytic reactor of claim 1, wherein cobalt, nickel, copper and/or mixtures thereof are the principal constituents of the support structure.

8. The catalytic reactor of claim 7, wherein the catalyst applied to the support structure is an activated metal catalyst.

9. The catalytic reactor of claim 8, wherein the catalytic fixed bed contains 2% to 17% by weight of aluminium based on the total mass of the catalytic fixed bed.

10. The catalytic reactor claim 7, wherein the activated metal catalyst is modified with a doping element selected from the group consisting of: molybdenum; platinum; palladium; rhodium; ruthenium; copper; and mixtures thereof.

11. The catalytic reactor of claim 1, wherein the catalytic fixed bed has a volume of 2 to 25 m.sup.3.

12. The catalytic reactor of claim 1, wherein the catalytic fixed bed has a fill-weight of between 0.1 and 1 kg/m.sup.3.

13. The catalytic reactor of claim 5, wherein the catalytically active components are selected from the group consisting of: iron; ruthenium; osmium; cobalt; rhodium; iridium; nickel; palladium; platinum; copper; silver; gold; and mixtures thereof.

14. The catalytic reactor of claim 13, wherein cobalt, nickel, copper and/or mixtures thereof are the principal constituents of the support structure.

15. The catalytic reactor of claim 14, wherein the catalyst applied to the support structure is an activated metal catalyst.

16. The catalytic reactor of claim 15, wherein the catalytic fixed bed contains 2% to 17% by weight of aluminium based on the total mass of the catalytic fixed bed.

17. The catalytic reactor claim 14, wherein the activated metal catalyst is modified with a doping element selected from the group consisting of: molybdenum; platinum; palladium; rhodium; ruthenium; copper; and mixtures thereof.

18. The catalytic reactor claim 15, wherein the activated metal catalyst is modified with a doping element selected from the group consisting of: molybdenum; platinum; palladium; rhodium; ruthenium; copper; and mixtures thereof.

19. The catalytic reactor of claim 13, wherein the catalytic fixed bed has a volume of 2 to 25 m.sup.3.

20. The catalytic reactor of claim 13, wherein the catalytic fixed bed has a fill-weight of between 0.1 and 1 kg/m.sup.3.

Description

EXAMPLES

(1) To demonstrate that the reactors of the invention resolve the typical conflict of objectives when operating reactors containing classical bulk materials, i.e. that the reactors of the invention are thus able to achieve the largest possible contact area between the reaction medium and the support while at the same time minimizing high flow resistances (minimization of the pressure loss across the catalytic fixed bed), the results of pressure-loss measurements in a catalytic reactor of the invention are presented.

(2) Provision of a Catalytic Reactor of the Invention:

(3) To form a support structure of the invention, eight commercially available cylindrical nickel foam bodies 80 millimetres in diameter and 250 millimetres in length and having a porosity of 95%, a pore size of 580 μm and a density of 742 kg/m.sup.3 were coated with binder by immersion in an aqueous binder solution containing 2.5% by weight of high-molecular-weight polyethyleneimine homopolymer and then coated with a wax-containing aluminium powder (containing 3% by weight of Ceretan 7080 wax) having a particle-size distribution with a d.sub.99 of 63 μm. The resulting weight ratio of applied aluminium powder to nickel foam body base was 0.27. The resulting body was heated in an atmosphere of oxygen-free nitrogen to 680° C. over a period of 10 minutes and held at this temperature for approx. one minute. The foam body was then “quenched” to approx. 200° C. and after this allowed to cool to room temperature. This heat-treatment resulted in the aluminium becoming alloyed in the nickel foam body with the formation of superficial intermetallic nickel-aluminium phases. Optical evaluation of scanning electron micrographs of embedded samples in cross section revealed the persisting presence in the interior of the nickel foam body of webs of pure nickel with a thickness of 10 μm. The support structure of the invention thus formed had a crosslinking density of 30 mm.sup.−3.

(4) In the next step, an activated metal catalyst was produced from the superficially applied intermetallic nickel-aluminium phases. For this, the aluminium fractions present in the intermetallic phases were dissolved out of the intermetallic phases by treatment with a 10% by weight sodium hydroxide solution. This was done by heating the support structures formed above in 10% by weight sodium hydroxide solution to 55° C. over a period of 30 minutes and treating them with sodium hydroxide solution at this temperature for approx. 30 minutes. The alkali was then removed and the support structures washed with water for approx. one hour.

(5) To form the catalytic reactor of the invention, the eight catalytic fixed beds thus produced were introduced into a glass tube having an internal diameter of 80 millimetres and a length of 2000 millimetres and fixed in place by means of a retaining plate at the bottom and a screening grid at the top. The eight catalytic fixed beds were introduced such that they were stacked on top of one another with no spaces in between and fixed in place so that they were resting firmly on the inner glass wall and unable to shift position with respect to one other, thus preventing any spaces from forming between the individual bodies. An inlet connector at the bottom and an outlet connector at the head were attached to the glass tube by means of ground-glass joints.

(6) The catalytic bed thus produced had a volume capable of reaction medium through-flow of 92.1 vol % and a catalyst contact area with the reaction medium of 4997 m.sup.2 per m.sup.3 volume of catalytic fixed bed.

(7) Pressure-Loss Measurements:

(8) In the catalytic reactor of the invention thus produced, the pressure loss across the catalytic fixed bed was determined with media of two different viscosities at various flow rates. The test media used for this were water (density: 1.015 g/ml; viscosity: 20 mPas) and ethylene glycol (density: 1.1018 g/ml; viscosity: 69 mPas). For the pressure-loss measurement, the test medium was fed into the reactor of the invention at various flow rates through the inlet connector at the bottom. The difference in pressure across the catalytic fixed bed was determined by means of pressure sensors in the reactor inflow and outflow.

(9) The results are presented in FIG. 5.

(10) Comparison with the Prior Art:

(11) Comparative data for catalytic fixed beds of the prior art were obtained by simulation calculation. A theoretical simulation was performed of the pressure loss across a packed fixed bed composed of particles of a non-porous bulk material having a cuboidal geometry of the dimensions 4×4×2 millimetres, the fixed bed formed from the bulk material having a diameter of 80 millimetres and a length of 2000 millimetres. Non-porous bulk material particles served as the comparison material of the prior art, since in the case of commercially available catalyst bodies of the prior art that are introduced into reactors as “heaped” catalyst beds, the reaction medium flows around them only externally. Although the internal porosity of the bulk material particles places limits on mass transport in the reaction process, it does not generally have any significant influence on the pressure loss observed across the catalyst bed.

(12) The pressure loss across the packing is calculated using the Ergun equation (source: Fluid flow through packed columns. Ergun, Sabri. 1952, Chem. Eng. Prog., p. 48.):

(13) $\Delta p=\frac{150\mu L}{D_p^2}\frac{{\left(1-ϵ\right)}^2}{{ϵ}^3}{v}_s+\frac{1.75L\rho }{D_p}\frac{\left(1-ϵ\right)}{{ϵ}^3}{v}_s.Math.v_s.Math.$
where:

(14) TABLE-US-00001 ϵ Porosity μ Fluid viscosity ρ Fluid density v.sub.s Fluid velocity D.sub.p Equivalent diameter L Tube length Δp Pressure loss

(15) This equation consists of a laminar term and a turbulent term that are differently weighted over the respective flow parameters according to the flow regime. When describing non-porous particles that the liquid or gas flows around only externally, the Ergun equation can be used to predict the pressure loss, the equivalent diameter in the case of cuboidal particles being calculated as follows:

(16) $D_p=\sqrt[3]{\frac{6.Math.a.Math.b.Math.c}{\pi }}$

(17) TABLE-US-00002 D.sub.p Equivalent diameter for the Ergun equation a Width of the particle cuboid b Length of the particle cuboid c Depth of the particle cuboid

(18) In the present case, the pressure loss was calculated as a function of the mass flow, with a mass flow considered that corresponded to the to the measurements in the catalytic reactor of the invention that are shown above.

(19) The comparison of the data obtained from the simulation with the data for the flow medium water measured in the catalytic reactor of the invention (density: 1.015 g/ml; viscosity: 20 mPas) shows that the pressure loss across the system of the invention is reduced by approx. 35-40% compared with the non-porous bulk material system (see FIG. 6).

(20) Investigations into Mechanical Stability:

(21) To demonstrate the high mechanical stability of the catalyst fixed bed, which allows catalyst breakage to be avoided over the operating lifetime, the results of investigations into the stability to breakage of samples of a support structure of the invention are presented in comparison with measurements on bulk material particles of the prior art.

(22) FIG. 7 shows by way of example the result of a compressive strength measurement on a sample of a support structure of the invention having the dimensions 4 mm×4 mm×2 mm carried out on a commercial Instron instrument for the determination of compressive strength.

(23) In addition, FIG. 8 shows the deformation of tested samples after performance of the compressive strength measurement.

(24) Measurement on a total of 20 samples did not show a single case of catalyst breakage. Even at forces of up to 80 N, all that was observed was pressure deformation (see FIG. 9).

(25) For comparison purposes, the compressive strength of 20 samples of a commercial nickel catalyst extrudate (bulk material of the prior art) of the Octolyst® series was investigated. Shaped bodies having dimensions of 2-5 millimetres, a bulk density of 0.7-1.3 kg/L and a nickel content of 15-50% by weight were subjected to corresponding compressive strength measurements. FIG. 10 shows the measurement curves obtained. In all cases the test ended with breakage of the catalyst body on application of forces between 20 and 110 newtons.

(26) FIG. 11 shows the tested bulk material of the prior art before the measurement and the broken material obtained as a result of the measurement.

(27) The support structure of the invention and catalyst fixed beds resulting therefrom show distinctly improved mechanical stability compared with catalyst fixed beds of the prior art which specifically avoids catalyst breakage over the operating lifetime of the catalytic reactor of the invention.

(28) A description of the figures is given hereinbelow:

(29) FIG. 1 shows illustrations (not drawn to scale) of sections of four different support structures of the invention (A|B|C|D), in which (1) material webs; and (2) crosslinks
are shown.

(30) FIG. 2 shows a microscopic image of a metallic support structure of the invention indicating (1) material webs and (2) crosslinks.

(31) FIG. 3 shows examples of tension-compression curves for determining the compressive strength of support structures of the invention, indicating the local maxima of the tension-compression curves to be evaluated.

(32) FIG. 4 shows in outline form (not drawn to scale) catalytic reactors of the invention in a trickle-bed design (A) and as a liquid-filled reactor (B), indicating (1) Reaction medium inflow; (2) Reaction medium outflow; (3) Hydrogen gas inflow; (4) Hydrogen gas outflow; (5) Sieve tray; and (6) Catalytic fixed bed of the invention.

(33) FIG. 5: Result of the pressure-loss measurement (water, ethylene glycol) in the reactor of the invention.

(34) FIG. 6: Comparison of the pressure loss across the fixed bed between the reactor of the invention and conventional bulk material system.

(35) FIG. 7: Example plot of the result of a compressive strength measurement on a sample of a support structure of the invention having the dimensions 4 mm×4 mm×2 mm.

(36) FIG. 8: Deformation of samples of support structures of the invention after performance of the compressive strength measurement.

(37) FIG. 9: Result of the compressive strength measurement of a total of 20 samples of support structures of the invention.

(38) FIG. 10: Result of the compressive strength measurement of a total of 20 samples of a commercial nickel catalyst extrudate of the Octolyst® series. Shaped bodies having dimensions of 2-5 millimetres, a bulk density of 0.7-1.3 kg/L and a nickel content of 15-50% by weight were investigated.

(39) FIG. 11: Nickel catalyst extrudate (prior art) before and after compressive strength measurements.