Enhanced Stability and Chemical Resistance of a New Nanoscale Biocatalyst for Accelerating CO2 Absorption into a Carbonate Solution

• Published in: Environmental science & technology Vol. 47; no. 23; pp. 13882 - 13888
• Main Authors: Zhang, Shihan, Lu, Hong, Lu, Yongqi
• Format: Journal Article
• Language: English
• Published: Washington, DC American Chemical Society 03.12.2013
• Subjects: Absorption, Physicochemical; Adsorption; Air pollution caused by fuel industries; Applied sciences; Biocatalysis; Carbon Dioxide - analysis; Carbonates - chemistry; Carbonic Anhydrases - metabolism; Climatology. Bioclimatology. Climate change; Earth, ocean, space; Energy; Energy. Thermal use of fuels; Enzyme Activation; Enzyme Stability; Enzymes, Immobilized - metabolism; Exact sciences and technology; External geophysics; Kinetics; Meteorology; Nanoparticles - chemistry; Nitrogen; Pollution reduction; Silicon Dioxide - chemistry; Solutions; Stack gas and industrial effluent processing; Temperature; X-Ray Diffraction; Zirconium - chemistry; Gas absorption; Carbon dioxide; CO2 sequestration; Carbon sequestration; Biocatalyst; greenhouse gas; sustainable development; Mitigation; Coal power plant; Carbonation; Physicochemical purification; Flue gas purification; Nanostructured materials; Potassium carbonate; climate change
• DOI: 10.1021/es4031744
• ISSN: 0013-936X

A novel potassium-carbonate-based absorption process is currently being developed to reduce the energy consumption when capturing CO2 from coal combustion flue gas. The process employs the enzyme carbonic anhydrase (CA) as a catalyst to accelerate the rate of CO2 absorption. This study focused on the immobilization of a new variant of the CA enzyme onto a new group of nonporous nanoparticles to improve the enzyme’s thermal stability and its chemical resistance to major impurities from the flue gas. The CA enzyme was manufactured at the pilot scale by a leading enzyme company. As carrier materials, two different batches of SiO2–ZrO2 composite nanoparticles and one batch of silica nanoparticle were synthesized using a flame spray pyrolysis method. Classic Danckwerts absorption theory with reaction was applied to determine the kinetics of the immobilized enzymes for CO2 absorption. The immobilized enzymes retained 56–88% of their original activity in a K2CO3/KHCO3 solution over a 60-day test period at 50 °C, compared with a 30% activity retention for their free CA enzyme counterpart. The immobilized CA enzymes also revealed improved chemical stability. The inactivation kinetics of the free and immobilized CA enzymes in the K2CO3/KHCO3 solution were experimentally quantified.