(353d) What's inside the Black Box? Understanding Enzymatic Conversion of CO2

Carbon capture and conversion to methanol is an essential part of the global transition towards net-zero emissions. Rare-metal catalysis is the most developed and researched method; however, it carries cost and sustainability concerns.

Enzymes are becoming increasingly recognized as a powerful and sustainable alternative, beginning with carbonic anhydrase which can increase hydration of CO₂. This new method presents challenges as enzymes must be robust enough to work within adverse environments, such as exhaust outflows. One of the most effective ways to solve these issues is through immobilization. Unfortunately, many studies are limited by the complex methodologies used to immobilize enzymes, loss of activity upon immobilisation, and loss of enzymes from the matrix.

This study seeks to explore the use of enzymes immobilised on a novel bioinspired silica framework for improved enzyme functionality and retention. By including a novel application of multi-wavelength scanning using UV-vis spectroscopy, it also hopes to elucidate the dynamic chemical process behind CO₂ conversion to methanol.

Using different bioinspired silicas pore sizes effects on the carbonic anhydrases immobilisation efficiency, retention, and stability were characterised. Specifically, the different bioinspired silicas were synthesised using pentaethylenehexamine, diethylenetriamine, and polyethylenimine/L-Arginine amine additives to create these different pore sizes. Further work was also done on the impact of varying temperature, pH, leaching, and storage time on carbonic anhydrase.

With the goal of creating an enzyme cascade to make methanol more enzymes were tested on bioinspired silica. Products and intermediates formate, formaldehyde, methanol and the co-factor NADH were tested over time within the immobilized system. Data from other dependent variables will also be presented, such the absence of carbonic anhydrase and the inclusion of a co-factor regeneration system.