直接空気回収において、低圧力損失・低熱容量の3D吸着材支持体が必要な理由

直接空気回収において、低圧力損失・低熱容量の3D吸着材支持体が必要な理由

ダイレクトエアキャプチャー, or DAC, is becoming an increasingly important technology pathway in carbon removal.

Unlike conventional carbon capture from concentrated industrial flue gas, DAC works with atmospheric air, where CO₂ concentration is much lower.

This means a DAC system must continuously process a very large volume of air.

As a result, DAC performance cannot be evaluated only by looking at the CO₂ adsorption capacity of the sorbent.

Airflow resistance, gas-solid contact, sorbent immobilization, structural weight, regeneration temperature, and cycling stability can all influence overall system efficiency.

For this reason, DAC development is gradually moving from a sorbent-only approach toward a more integrated engineering model:

Sorbent Chemistry + Porous Structure + Airflow + Thermal Management + Module Design

1. DAC Is Not Only About the Sorbent

Most discussions around DAC naturally focus on the sorbent chemistry.

Common research areas include:

• Amine-based sorbents
• Alkaline materials
• 金属有機フレームワーク
• Porous polymers
• Functional porous materials
• Hybrid solid sorbent systems

These materials are responsible for the chemical interaction with CO₂.

However, a sorbent cannot operate independently inside a practical DAC module.

It must be supported, coated, immobilized, or distributed within a structure that allows air to pass through while maintaining sufficient contact between the gas and the active sorbent.

実用的 DAC module therefore needs to answer two different questions:

Can the sorbent capture CO₂ effectively?

(NAIST) と

Can air move through the adsorption structure with acceptable energy consumption?

The second question is where structured sorbent supports become especially important.

2. Why Pressure Drop Matters in DAC

One of the fundamental differences between DAC and point-source carbon capture is the volume of gas that must be processed.

Because atmospheric CO₂ concentration is low, a DAC system must move a large amount of air to capture a meaningful amount of CO₂.

Every structure placed in the airflow creates resistance.

Pressure drop can increase when:

• The adsorption bed is too thick
• Pore channels are too small
• Sorbent loading is too dense
• Flow paths become highly tortuous
• Coatings partially block open pores

Higher pressure drop means:

Higher fan power demand.

For large-scale DAC systems, this auxiliary energy demand can directly influence operating efficiency and cost.

An important engineering goal is therefore to maintain sufficient sorbent loading and gas-solid contact while minimizing airflow resistance.

3. More Sorbent Is Not Always Better

From a materials perspective, increasing sorbent loading may initially seem desirable.

But in a structured DAC system, maximum loading is not necessarily the optimum condition.

If excessive sorbent blocks the porous structure, several problems can occur:

• Increased airflow resistance
• より高い圧力損失
• Reduced open flow channels
• Lower utilization of internal sorbent
• Slower adsorption kinetics
• Slower desorption

The real design challenge is to balance:

Sorbent Loading × Mass Transfer × Pressure Drop

rather than optimizing sorbent loading alone.

4. Why Low Thermal Mass Also Matters

Many solid-sorbent DAC systems use thermal energy to release captured CO₂ and regenerate the sorbent.

During this regeneration step, energy may be used not only to heat the sorbent itself, but also to heat:

• サポート構造
• フレーム
• 機械的な支持構造
• Internal module components
• Other non-active materials

If the structural support is heavy, every cycle may involve repeatedly heating a significant amount of material that does not directly contribute to CO₂ capture.

Reducing non-active structural mass can therefore be an important engineering objective.

A lower-density support may potentially reduce the amount of non-active material involved in each heating and cooling cycle.

However, it is important to be precise:

Low density does not automatically mean lower total DAC energy consumption.

Actual system energy depends on heat capacity, sorbent chemistry, regeneration temperature, heat-transfer efficiency, module architecture, and operating cycle design.

These potential advantages must therefore be validated experimentally.

5. Structured Sorbents Are Becoming More Important

Traditional adsorption systems often rely on packed beds.

Packed beds are simple and well understood, but they may introduce engineering limitations such as:

• Complex airflow paths
• より高い圧力損失
• 粒子摩耗
• Dust formation
• Non-uniform heat transfer

This is one reason why structured sorbents are receiving growing attention.

そのコンセプトは単純明快だ。

Instead of filling a module with loose particles, the sorbent is distributed onto or within a pre-designed structure.

This allows engineers to optimize independently:

• Flow channel geometry
• 表面積
• Sorbent-layer thickness
• 圧力降下
• 熱伝達
• 機械的安定性

6. Comparison of Common DAC Sorbent Structures

No single structure is optimal for every DAC system.

適切なアーキテクチャは以下に依存します。

• 風量
• Sorbent chemistry
• 再生方法
• モジュールの寸法
• 目標耐用年数

7. Why Open-Cell Foam Is Worth Evaluating

Open-cell foam behaves differently from a honeycomb structure.

A honeycomb typically contains relatively regular, straight channels.

Open-cell foam contains an interconnected three-dimensional pore network.

This allows gas to travel through multiple pathways inside the material.

From an engineering perspective, this structure may offer several interesting characteristics.

3D Airflow Pathways

The interconnected pore network allows air to pass through the structure in multiple directions.

This may help create more effective interaction between the gas stream and the functional sorbent surface.

Low Structural Weight

Low-density foam can occupy a relatively large volume while using a relatively small amount of support material.

This may be useful in DAC modules where both structural weight and thermal mass are important.

調整可能な構造

Thickness, dimensions, density, and surface treatment can be adapted to different module concepts.

簡単な変換

Open-cell foam can be cut, CNC-machined, laminated, or converted into different prototype geometries.

This can be especially useful during early-stage DAC module development.

8. The Potential Role of Melamine Foam in DAC

シノイQX メラミンフォーム is a low-density, three-dimensional open-cell porous material.

The typical density of the standard engineering grade is approximately:

8.5kg /m³

From a DAC engineering perspective, it can be evaluated as a:

軽量3D吸着材サポート

Its potential role is not to act as the CO₂ sorbent itself, but to provide:

• A three-dimensional porous support structure
• 気流経路
• A substrate for sorbent immobilization
• A customizable module geometry
• Low structural mass

9. Melamine Foam Is Not the CO₂ Sorbent

この区別は重要です。

スタンダード メラミンフォーム should not be presented as a direct CO₂ sorbent for DAC.

In a DAC system, the actual CO₂ capture function comes from materials with appropriate chemical affinity or selectivity for CO₂.

これらには、

• Amine-functional materials
• 金属有機フレームワーク
• Alkaline sorbents
• Functional porous polymers
• Other CO₂-selective sorbent systems

The more realistic role of melamine foam is to serve as a three-dimensional structural support for these active materials.

The final DAC material system should therefore be understood as:

3D Support + Functional Sorbent

rather than as a single foam material.

10. How Can Sorbents Be Loaded onto 3D Foam?

This is one of the central development questions.

Depending on the sorbent chemistry, several loading approaches can be evaluated.

表面コーティング

A functional sorbent layer is applied to the foam skeleton.

含浸

The open-cell structure is impregnated with a functional material.

Polymer Functionalization

The foam surface is chemically or physically modified with functional groups or polymers.

複合構造

The foam is combined with membranes, fibers, coatings, or other sorbent-containing layers.

Each route may affect:

• 吸着剤の負荷
• Pore blockage
• 圧力降下
• 吸着速度論
• コーティング接着
• サイクリングの耐久性

For this reason, the loading method must be evaluated together with the structure.

11. What Should Be Tested in a DAC Sorbent Support?

A material should not be selected for DAC based only on density or porosity.

The more important step is module-level engineering validation.

Pressure Drop vs Air Velocity

Measure pressure drop over a range of airflow velocities.

This is one of the most important indicators of aerodynamic performance.

吸着剤の負荷

Determine how much functional sorbent can be stably loaded per unit mass or volume of support.

CO₂吸収

It is useful to evaluate both:

g CO₂ / kg Sorbent

(NAIST) と

キロ CO₂ / m³ Module

because practical DAC systems are also constrained by module volume.

吸着速度論

Measure how quickly CO₂ can reach and interact with the sorbent.

Desorption Kinetics

Measure how efficiently CO₂ can be released during regeneration.

熱質量

Evaluate the thermal load associated with the foam, sorbent, and other structural materials.

湿度安定性

Ambient air contains moisture, so humidity effects on both the sorbent and support structure must be considered.

サイクリングの安定性

Long-term DAC operation requires repeated adsorption-desorption cycles.

主な所見は次のとおりです。

• Sorbent loss
• コーティングのひび割れ
• Foam deformation
• Pressure-drop changes
• Adsorption-capacity decay

12. Different DAC Systems May Need Different Foam Structures

SINOYQX approaches DAC as a joint-development application rather than as a single fixed foam grade.

Potential material directions include:

標準オープンセルフォーム

For early-stage sorbent loading and material screening.

Low-Pressure-Drop Structure

For systems where airflow resistance and fan energy are especially important.

疎水性フォーム

For evaluating structural behavior under high-humidity air conditions.

Reinforced Foam

For modules requiring improved mechanical stability.

カスタムジオメトリ

For CNC-cut or custom-shaped structures based on specific DAC module dimensions.

There is no universal “best” foam structure.

The correct design depends on the sorbent chemistry and the DAC system architecture.

13. From Material Screening to DAC Module Validation

A practical development route usually does not start with a full-scale DAC system.

より効率的なアプローチは次のとおりです。

ステップ 1

Define the CO₂ sorbent chemistry

ステップ 2

Screen suitable 3D support structures

ステップ 3

Evaluate sorbent-loading methods

ステップ 4

Establish the Air Velocity–Pressure Drop relationship

ステップ 5

Test CO₂ uptake and adsorption kinetics

ステップ 6

Run adsorption-desorption cycling tests

ステップ 7

Move into small-scale DAC module validation

Only after these steps can the real engineering value of the support structure be assessed.

14. SINOYQX Joint Development for DAC

SINOYQX develops メラミンフォーム, hydrophobic porous materials, aerogel composites, and other functional porous structures.

For Direct Air Capture applications, we are exploring the engineering potential of melamine foam as a lightweight three-dimensional sorbent support.

Our current focus includes:

• 泡密度
• 細孔構造
• 厚さ
• Module geometry
• 風速
• 圧力降下
• 表面処理
• 吸着剤の負荷
• 湿度
• サイクリング時の安定性

Our objective is not simply to offer a “DAC foam.”

The goal is to help development teams evaluate a porous support structure that fits their sorbent chemistry, airflow requirements, regeneration method, and module design.

工学的境界

Melamine foam itself should not be described as a DAC CO₂ sorbent.

Potential benefits associated with open-cell structure, low density, and low structural mass must be validated under the actual sorbent chemistry, airflow rate, module geometry, and operating cycle.

Material-level performance should not be interpreted as equivalent to full DAC system energy efficiency or CO₂ capture performance.

FAQ

Can melamine foam directly capture CO₂?

Standard melamine foam should not be considered the primary CO₂ sorbent in DAC. Its more appropriate role is as a three-dimensional porous support for functional sorbent materials.

Why is pressure drop so important in DAC?

DAC systems must process very large volumes of air. If airflow resistance is too high, more fan power is required, which increases auxiliary energy consumption.

Why does DAC benefit from low-thermal-mass supports?

In thermally regenerated systems, the support structure may also need to be heated and cooled. Reducing non-active structural mass may reduce the amount of material repeatedly involved in thermal cycling, although total system energy must still be validated experimentally.

What is the difference between open-cell foam and honeycomb structures?

Honeycomb structures usually contain regular flow channels, while open-cell foam contains a three-dimensional interconnected pore network. The two structures differ in airflow behavior, surface geometry, sorbent loading, and manufacturing flexibility.

What is the typical density of SINOYQX standard melamine foam?

The standard engineering grade has a typical density of approximately 8.5 kg/m³. Functional grades should be selected according to the corresponding technical specification or project requirement.

What should be tested first in a DAC support project?

Priority testing should include sorbent loading, pressure drop versus air velocity, CO₂ uptake, adsorption/desorption kinetics, humidity stability, coating adhesion, and cycling durability.

CTA

Developing a Solid-Sorbent DAC Module?

If you are evaluating a structured sorbent support, please provide:

Sorbent type,airflow rate,module dimensions,allowable pressure drop,operating temperature,regeneration method,ambient humidity,target sorbent loading,cycling requirements

SINOYQX can support the evaluation of different foam densities, thicknesses, pore structures, surface treatments, and custom geometries for prototype testing.

Submit Your DAC Project Conditions →