DE102022203604A1 - Powder, ceramic wall, reaction chamber and process - Google Patents

Abstract

The invention relates to a ceramic powder for producing a ceramic component, the powder having at least grain sizes in the range from 1µm to 5mm with a proportion of less than 95% by mass.

Description

The invention relates to a powder, a ceramic wall that can be used for reaction chambers, and a method for producing it.

In the area of Power-to-X applications, as shown in the US 2005/0014641 A1 As is well known, surplus energy is used to produce synthetic raw materials, gases or fuels. This requires adapted processes that take place at higher temperatures in reaction combustion chambers. The conversion processes take place on membranes or catalysts that are coated with reactive elements, as can be seen from the EP 1 789 172 A1 is known. Due to the operating conditions, the use of ceramic materials as catalysts/membranes is recommended.

Due to their design, existing concepts have high heat losses and therefore low efficiency.

It is therefore the object of the invention to solve the above-mentioned problem.

The object is achieved by a powder according to claim 1, a method of production according to claim 7, a ceramic wall according to claim 14 and a reaction chamber according to claim 15.

The subclaims list further advantageous measures that can be combined with one another in any way to achieve further advantages.

The thermal efficiency of currently available concepts offers potential for improvement and can also be further improved through the use of heat exchangers.

• 1, 2 schematisch Herstellungsverfahren,
• 3 schematisch eine keramische Wand und
• 4 eine Reaktionskammer.

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• 1 , 2 schematic manufacturing process,
• 3 schematically a ceramic wall and
• 4 a reaction chamber.

Many chemical reactions occur at elevated temperatures, so thermal insulation or heat exchangers can increase the efficiency of the overall system.

At this point, ceramics have significant advantages: in addition to the low thermal conductivity and good heat capacity for storing thermal energy, the raw material costs are low.

In addition to thermal efficiency, the use of additive manufacturing, such as 3D printing in particular, to produce such a system can contribute to a further increase in chemical conversion, as it allows the chemically active surface to be increased through design optimization of the geometry.

The particle sizes of a ceramic powder used according to the invention used for the production of a ceramic component according to the invention, such as a ceramic wall, in particular for a reaction chamber or a heat exchanger, are in the range from 1 μm to 5mm. In particular, the proportion of 1µm to 3mm is in the range of less than 95%.

The minimum proportion of these particles with sizes of 1µm to 5mm is, in particular, at least 60%, especially at least 70%.

The powder preferably has a Gaussian distribution curve for the grain size distribution.

A particle size of greater than 1 mm with a proportion of less than 40%, in particular with a proportion of less than 30%, is also advantageous.

The minimum proportion of these particle sizes of greater than 1 mm is at least 10%, in particular at least 20%.

In addition, a proportion of particles up to 250nm of less than 5% is advantageous.

Oxides such as aluminum oxide, zirconium oxide, barium oxide, titanium oxide, tungsten oxide, etc. and/or mixtures thereof are particularly suitable as materials.

A targeted surface influence with reactive elements, so-called promoters, such as nickel (Ni), iron (Fe), cobalt (Co), ruthenium (Ru) etc., with a proportion of 0.1% to 5%, which are responsible for the expiring chemical reactions are responsible can be specifically implemented during production.

The promoters can also be introduced using a separate powder mixture.

A sintering process of the powder blank for the component with promoters in a reducing atmosphere can be useful.

The promoters can preferably also be present as oxides.

A ceramic component or a ceramic wall made from the powder according to the invention is preferably produced by a binder jet process.

In principle, a distinction can be made between water-based and solvent-based binder systems. The water-based ones achieve a higher green strength compared to the solvent-based ones.

As part of the process, the binder-containing intermediate product produced in this way is debinded and sintered.

It is advantageous to apply the coating with promoters in a two-stage process, whereby the ceramic wall or component is first fired and the reactive elements/promoters are introduced in a separate step.

This is in 1 shown in more detail, in which a powder blank 1 'for a ceramic component 1 was produced using the powder described above and was debinded and / or sintered (T) in an oven 10 and results in a compacted component 1.

The promoters are then applied and/or introduced into an outer region 4 of the ceramic component 1.

An alternative to this is the subsequent introduction into the sintered component 1 using a type of “wash-coat”. The “wash-coat” process is known from the automotive industry for producing catalytic converters (exhaust).

Another alternative is schematically in 2 shown, in which a part of a ceramic wall 11" has already been produced as a powder blank, which was applied to a surface 16 using powder and binder according to the invention from a reservoir 13 (schematically).

Then a powder mixture of the above-mentioned ceramic powder and one or more promoters, in particular a metallic powder, is applied.

This is in 2 shown on the right, in which an outer region 44 is applied for the first time from a reservoir 14 (schematically) with a ceramic powder 13 and a promoter, which already has a physical mixture of ceramic powder and promoter.

The powder or the powder mixture is in turn applied to the surface and then represents an outer region 44 of a ceramic wall 21.

Two reservoirs for ceramic powder and promoter can also be used (not shown).

In both cases, the thermal treatment of the component 11 'as described above takes place in the oven 10.

3 schematically shows a ceramic wall 21 which has a denser area 24, the denser area 24 being gas-impermeable and the ceramic wall 21 having a gas-permeable or open-pored area 27.

The thickness ratios of the areas 24, 27 are only schematic.

The open-pored area 27 can preferably also be thicker than the gas-tight area 24, which only acts as a support.

The transition from the denser area 24 to the gas-permeable area 27 can preferably also be made in a graded manner, i.e. H. in a region 30 the porosity changes continuously or discontinuously step by step.

This 2-layer structure can preferably also be produced in one step.

The production of the gas-permeable and gas-impermeable areas of the reactor walls can be controlled by using different binder systems for the respective areas 24, 27 with different fillers, which, for example, contribute to a targeted improvement in local sintering.

To increase the density, especially for the gas-tight area 24, a sintering aid can be used in the powder according to the invention.

The sintering aid preferably has silicon oxide and/or aluminum oxide.

The sintering aids are preferably mixed into the binder, in particular in a weight proportion of 1 percent by weight to 20 percent by weight, based on the binder content.

The sintering aid preferably has grain sizes of up to a maximum of 10 μm and also has proportions of at least 1% in the submicrometer range.

A gas-tight region 24 can be created by varying the grain size distribution during printing, ie the powder according to the invention is deviated from in sections here.

Other options include post-infiltration or coating.

4 shows a reaction chamber 20 which has a ceramic wall 11 which was produced using the powder according to the invention.

Likewise, the reaction chamber 20 can have a wall 21 according to 3 have, in which the gas-permeable area 27 limits the interior 33.

The interior 33 represents the combustion chamber in which the reactions take place, which are supported by the promoters that may be present in the gas-permeable area 27.

Likewise, the reaction chamber 20 can have a metallic framework, which is optionally cooled.

The reaction chamber 20 is characterized in that it has gas-tight and gas-permeable 27 areas. A gas-permeable region 27 is achieved by manufacturing using the above-mentioned powder. To produce the gas-tight area, the wall produced in this way can be applied to a gas-tight substrate or connected to one.

A simultaneous optimization of the geometry with regard to the active surface can be integrated directly into the production of the reactors using 3D printing technology. The promoters that are added later today to trigger the chemical reactions can also be implemented directly during 3D production.

An increase in the thermal efficiency of the reactors is achieved by implementing a heat exchanger.

When producing a ceramic wall for a reaction chamber, the gas-tight region is preferably first produced using the powder according to the invention and the binder with the sintering aid.

The gas-permeable area can be printed directly afterwards and onto the gas-tight area.

The gas-permeable region can be treated with the promoters as described above after it has been sintered.

Likewise, for the production of a reaction chamber, the ceramic wall, in particular with the gas-impermeable and the gas-permeable area, can be printed directly with a heat exchanger or printed onto a heat exchanger.

QUOTES INCLUDED IN THE DESCRIPTION

This list of documents listed by the applicant was generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• US 2005/0014641 A1 [0002]
• EP 1789172 A1 [0002]

Claims (15)

Ceramic powder for the production of a ceramic component, where the powder has at least grain sizes in the range from 1µm to 5mm, especially in the range from 1µm to 3mm, with a proportion of less than 95% by mass has and in particular has a Gaussian distribution. powder after Claim 1 , in which the proportion of the powder with grain sizes in the range from 1µm to 5mm, in particular in the range from 1µm to 3mm, is at least 60% by mass, in particular at least 70% by mass. Powder after one or both of the Claims 1 or 2 , in which the proportion of the powder with grain sizes of greater than 1 mm has a proportion of less than 40% by mass, in particular less than 30% by mass, and in particular a minimum proportion of at least 10%, in particular of at least 20%. Powder after one or more of the Claims 1 , 2 or 3 , in which the proportion of powder with grain sizes up to 250nm is less than 5% by mass. Powder after one or more of the Claims 1 , 2 , 3 or 4 , which has at least one oxide, in particular aluminum oxide, zirconium oxide, barium oxide, titanium oxide, tungsten oxide or mixtures thereof. Powder after one or more of the Claims 1 , 2 , 3 , 4 or 5 , to which promoters of 0.1% to 5% are added to provide a catalyst, in particular in which metallic promoters, in particular selected from the group of nickel (Ni), iron (Fe), cobalt (Co), ruthenium (Ru), are used which can be oxidized, particularly during further treatment of the powder. Method for producing a ceramic wall (11, 21) using a ceramic powder according to one or more of Claims 1 , 2 , 3 , 4 , 5 or 6 , in which an additive manufacturing process is used, in particular a binder jet process, with sintering being carried out after debinding. Procedure according to Claim 7 , in which a powder mixture consists of a powder according to one or more of the Claims 1 , 2 , 3 , 4 , 5 or 6 and promoters is used only to produce an outer region (44) of a ceramic wall. Procedure according to Claim 7 or 8th , in which metallic promoters are used in the additive manufacturing process, which are oxidized in particular during further processing of the powder. Procedure according to Claim 7 , 8th or 9 , for producing a gas-tight ceramic wall (21), the powder according to one or more of the preceding Claims 1 until 7 Sintering aids are added, in particular in which binders are added, in order to produce a gas-tight area (24) as part of the ceramic wall. Procedure according to Claim 10 , in which the sintering aids have silicon oxide (SiO2) and/or aluminum oxide (Al2O3), in particular with grain sizes <= 10pm and proportions in the submicrometer range. Procedure according to one or both of the Claims 10 or 11 , in which the sintering aids are mixed into the binder in a proportion of at least 1 percent by weight to a maximum of 20 percent by weight. Method according to one or more of the preceding Claims 7 until 12 , in which a ceramic wall (11, 21) is printed together with a heat exchanger or is printed directly on a heat exchanger. Ceramic wall having a porous area (27) or produced according to one or more of the preceding Claims 7 until 13 , which has, in particular, elemental nickel, iron, cobalt, ruthenium and mixtures thereof or their oxides as promoters on its outer surface area (4, 44). Reaction chamber (20), having a ceramic wall (11, 21), in particular according to Claim 14 , made according to or more of the foregoing Claims 7 until 13 , in particular printed on a heat exchanger or printed together with a heat exchanger.

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