Tianjin University Team Develops a Membrane That Cuts Carbon Capture Costs to $38 a Tonne

October 8 (IT Home) — According to Xinhua, a team led by Jiang Zhongyi and He Guangwei at Tianjin University has developed a new fully organic mixed-matrix membrane, overcoming the difficulty of balancing separation performance with processability, and offering a new materials pathway for low-energy, low-cost carbon capture from industrial gases.

The result was published online in Nature Energy on 7 October, with collaborators including researchers from the Swiss Federal Institute of Technology Lausanne (EPFL) and the University of Southern California.

Carbon capture is an important part of meeting “dual carbon” goals. The industrial gases emitted by power plants, cement works and steel mills contain relatively low concentrations of carbon dioxide but very large total volumes, and conventional separation methods are energy-intensive and costly. Membrane separation is green, low-carbon and energy-saving, and is seen as a highly promising carbon capture technology. However, capturing carbon from industrial flue gas requires membranes that combine high permeance, high selectivity, long-term stability and easy scale-up. Mixed-matrix membranes combine the processability of polymers with the efficient transport of porous fillers, but the two materials have very different properties, creating compatibility problems. Traditional approaches try to “stick” the two materials together more firmly by strengthening the forces between them, with limited effect: separation performance is still dominated by the polymer, and the porous filler struggles to play a role.

To tackle this, the team drew inspiration from the structure of cell membranes and proposed a “weak interfacial force embedding” strategy, combining single-crystal covalent organic frameworks (COFs) with ordered channels and a polymer to create a fully organic mixed-matrix membrane. By coordinating the filler-polymer and filler-filler interactions, the COF is embedded evenly in the membrane at high loading, genuinely “taking the leading role” in molecular transport while the membrane retains its flexibility and solution processability, building ultrafast transport channels for carbon dioxide. According to ScienMag, the team raised the single-crystal COF loading to a volume fraction of 75.5% — a proportion previously considered very difficult to achieve in mixed-matrix membranes. At such high loading, the filler is no longer a minor additive but becomes the dominant continuous network for gas molecule transport.

In tests with simulated flue gas mixtures, the fully organic mixed-matrix membrane achieved an order-of-magnitude improvement in carbon dioxide permeance, breaking the record reported in the literature and reaching about 70% of the theoretical value predicted for a pure COF membrane. According to figures disclosed by ScienMag, the membrane reached a carbon dioxide permeance of 74,800 Barrer while maintaining a carbon dioxide/nitrogen selectivity of about 20. By comparison, commercial polymer membranes in post-combustion carbon capture typically have permeance in the range of tens to low hundreds of Barrer. The membrane also showed good long-term stability, holding its performance under test conditions containing moisture, sulphur oxides and nitrogen oxides.

A preliminary techno-economic analysis, under the assumed process and cost conditions, put the carbon capture cost at about US$38 (about 255.1 yuan at current exchange rates) per tonne of carbon dioxide.

According to the energy innovation review site, a team led by Lin Zhihong at the Guangdong Technion-Israel Institute of Technology had previously used a heat-driven chemical modification strategy to cut carbon capture costs from about US$68 to about US$38 per tonne, a reduction of about 44%. Data from Columbia Business School and Nature Sustainability and other sources indicate that the cost of membrane-based carbon capture generally falls between US$26 and US$80 per tonne, while conventional amine-based absorption costs between US$30 and US$66 per tonne.

Jiang Zhongyi, the paper’s corresponding author, said: “Turning the difficult problem of industrial carbon reduction into a scientific question about advanced membrane materials is the direction we have been working on for a long time.”

The result provides a new approach to developing membrane materials that combine performance, stability and processability, and is expected to be applied in flue gas carbon capture in the power, cement and steel industries — helping to move carbon capture membrane technology towards industrial application.