Catalysts are used in reactors to facilitate or accelerate gas or liquid reactions. This creates a unique demand for balancing surface area, flow, and heat resistance. In the past, engineers often had to compromise, choosing between structures that promoted good mixing, strong structures, or structures that could be easily and reliably manufactured. Sinto Advanced Ceramics (formerly Bosch Advanced Ceramics) aims to remove these limitations by adopting a new technology: 3D printed ceramics from Formlabs.

Since 2016, Sinto Advanced Ceramics has used 3D printing technology to produce high-performance ceramic parts with complex geometries for the semiconductor, chemical, aerospace, and automotive industries. Formlabs' stereolithography (SLA) 3D printers enable cost-effective production and scalable manufacturing of certain parts, from prototyping to mass production.

The catalytic converter for the chemical industry, printed with Alumina 4N Resin on a Form 4 SLA 3D printer, exemplifies the importance of accurate, flexible, and responsive additive manufacturing technology for Sinto Advanced Ceramics.

Design Requirements for Catalysts in Chemical Reactors

Catalytic converters are used within reactors to facilitate or accelerate gas or liquid reactions. These devices need to withstand mechanical loads at high temperatures while also having a larger surface area than traditional catalysts. Therefore, a critical challenge lies at the intersection of "materials" and "structure."

A better catalyst structure helps reactions occur faster, increases efficiency, and extends the lifespan of parts, which in turn reduces costs and enhances sustainability in chemical production processes.

In terms of design, catalytic converters must have a large surface area, good flow properties, and efficiently mix reactants. The problems with traditional catalysts are as follows:

1. Extruded honeycomb structures do not facilitate the mixing of reactants.
2. Open foams have an uncertain and immeasurable surface area.
3. Fixed beds do not promote substance flow.

A periodic open-cell structure is crucial for the efficiency of catalytic converters, as it serves as a support structure for catalytic materials capable of accelerating chemical processes.

Engineers at Sinto Advanced Ceramics have developed a solution to this problem by creating a "diamond structure" composed of struts with a thickness of only 2 millimeters, mimicking the atomic bonding characteristics within a diamond crystal. Gases or liquids flow through this highly porous structure, and upon contact with the catalyst coated on the surface, these substances react with each other.

Unlike foam or fixed bed catalysts, this diamond structure is a precisely defined and detailed geometry that can be consistently reproduced, making it ideal for manufacturing with 3D printing technology and ensuring uniformity in each piece.

During the proof of concept phase, catalysts were printed from plastic and then coated. However, the properties of this material could not provide the required mechanical strength, which ultimately led to the selection of Alumina 4N Resin.

Direct Printing of Alumina

“In research, catalysts for proof of concept are typically produced by printing the base structure from plastic and then coating it with Al₂O₃. Directly printing the structure from Al₂O₃ allows us to create more stable structures and reduce manufacturing steps.”

Malte Hartmann
Malte Hartmann
Development Engineer, Sinto Advanced Ceramics

Alumina 4N Resin enables direct 3D printing with high-purity alumina engineering ceramics up to 99.99% and a relative density of 98.6%.

This material offers exceptional performance for applications in harsh or challenging environments, with the following key properties:

1. Excellent high-temperature resistance (Thermally Resistant)
2. High hardness (Hard)
3. Abrasion and wear resistance (Abrasion Resistant)
4. High mechanical strength (Mechanically Strong)
5. Chemically inert or highly resistant to chemical reactions (Chemically Inert)

These properties make Alumina 4N Resin suitable for manufacturing high-performance ceramic parts that face heat, wear, mechanical stress, and harsh chemicals in various industrial applications.

By eliminating the use of plastic base structures and removing the post-coating step, Sinto Advanced Ceramics can simplify the manufacturing process, enhance mechanical strength reliability, and enable the true series production of ceramic catalysts.

Parts printed with Alumina 4N Resin must undergo cleaning with Ceramic Wash Solution, then drying and firing.

Since this alumina material was developed by Formlabs specifically for their Form Series 3D printers, the shrinkage rate can be precisely known. Additionally, the material leverages the Low Force Display (LFD) technology of the Form 4 to enable high-precision printing.

Sinto Advanced Ceramics can control part tolerances to less than 200 micrometers (µm), while customers require tolerances not exceeding 0.5% of the nominal dimension, which is strong evidence of the manufacturing process's precision.

1. Dimensions: 8 cm diameter, 10.1 cm height
2. Weight: 313 grams
3. Manufactured with: Form 4 3D printer using Alumina 4N Resin

Flexible and Economical Scalable Production

For Sinto Advanced Ceramics, choosing additive manufacturing technology is not just about design freedom and the ability to produce complex geometries. The Form 4 and Alumina 4N Resin also provide an economically viable solution for manufacturing.

“At Sinto Advanced Ceramics, we utilize a variety of manufacturing technologies and select the most suitable solution based on customer needs. Formlabs printers offer a distinct advantage by allowing us to scale production flexibly and support growth simply by adding more machines to the production system. This factor is a key reason why we chose additive manufacturing technology and further solidifies Formlabs' role as a partner for innovative, economically viable, and scalable manufacturing solutions.”

Nikolai Sauer
Nikolai Sauer
General Manager, Sinto Advanced Ceramics

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References

https://formlabs.com/global/blog/sinto-advanced-ceramics-alumina/