Producing Green Energy Through CO2 Capture and Conversion

 


By Associate Professor Yan Ning

NUS Chemical and Biomolecular Engineering

Greenhouse gases trap sunlight energy. This has contributed to making the Earth's climate habitable for humans and other living things. However, the balance is now shifting. The intensification of human activity that has followed industrialization has introduced too much CO2 into the atmosphere.

Annual CO2 emissions have sharply increased from less than 1 billion ton before the industrial revolution to what is currently 36 billion ton [1]. This has led to a global temperature increasing by over 1 degree Celsius [2].

Today, climate change, together with depleting global resources, remain the top challenges globally.

One solution to mitigate these challenges is to design self-regulated circular pathways that utilize CO2 for energy generation. Such efforts are being pursued at NUS, where researchers under the NUS Flagship Green Energy Programme are pursuing the synthesis of green fuels from small molecules.

This is being achieved through CO2 capture from flue gas and ultimately from air, solar-powered hydrogen production, and CO2 hydrogenation into fuel compounds.

This integrated approach ultimately aims to store energy from sunlight as liquid fuels. Upon utilization, CO2 and H2O may be returned to the environment for reuse, thus emulating nature’s energy-carbon-water cycle.

One effort that aims to develop catalytic materials for CO2 adsorption and catalytic transformation is being led by Associate Professor Yan Ning from NUS Chemical and Biomolecular Engineering. In their work the team is focusing on an emerging type of material, namely single-atom/cluster doped catalysts, to tackle CO2 adsorption and conversion.

Here, doping of single-atom/clusters may precisely modify the geometric characteristics of porous material to induce exceptional selectivity in gas sieving, thereby enabling gas adsorption.  Similarly, single-atom catalysts may facilitate gas conversion by maximising the dispersion of metal atoms on a catalyst surface. In these cases the electronic structure and geometric configuration of the catalysts, and their performance in a range of energy-related applications, are being investigated.  

In the past several years, the team has developed high density single-atom catalysts with increased stability under high temperature, prepared new zeolite catalysts with single atoms and clusters encapsulated, and reported systems with enhanced CO2 adsorption and conversion performances.

The development of low-cost, efficient physisorbents CO2 adsorption, is essential; however, the intrinsic tradeoff between capacity and selectivity greatly limits their practical separation efficiency.

Recently, mordenite zeolite doped by isolated Fe clusters (Fe-MOR) was developed for CO2 sieving [3]. This joint effort, which involved researchers from 11 institutes, was led by three teams in Nanjing Tech University, Zhejiang University and National University of Singapore.

Mordenite monolith is a typical material for gas adsorption, but it is not selective due to the overly large pore diameter. By careful selection of the synthetic condition, isolated tetrahedral Fe species were controllably located inside the 1D microporous channels, leading to a zeolite pore system of precisely narrowed microchannels that only allows CO2 to enter even when N2 or methane are present.

YanLab

 

Moreover, the new material exhibited excellent stability to work under high moisture. These remarkable features make the material a highly promising candidate to purify CO2 from flue gas or remove CO2 from natural gas.

Assoc Prof Yan and his team will explore the catalytic conversion of CO2 trapped inside the zeolite pores which will involve replacing Fe with a more active metal for CO2 conversion, without comporting the pore diameter confinement effect.

References 

[1] “CO2 emissions (2020)" Carbon Dioxide Analysis Center in US DOE
[2] "Why does the temperature record shown on your "Vital Signs" page begin at 1880?" NASA, Retrieved from:  https://climate.nasa.gov/faq/21/why-does-the-temperature-record-shown-on-your-vital-signs-page-begin-at-1880/
[3] Science 373, 315–320 (2021)

NingYAN
Assoc Prof Ning YAN's  major research interest includes catalytic conversion of renewable carbon sources, green chemistry & engineering, and catalyst development. He was awarded the NUS Young Researcher Award 2019 for his contributions to the conversion of biomass to value-added chemicals and the fields of nano- and single-atom catalysis.




Contact

Associate Professor Ning YAN
E: ning.yan@nus.edu.sg
P: +(65) 6516 2886
W: http://yan-nus.weebly.com/

  • Home
  • Producing green energy through CO2 capture and conversion