SOLAR FUELS AND A HYBRID PROCESS THEREOF BASED ON BIOMIMETIC CARBONATION AND PHOTOCATALYSIS

摘要

The present invention is related to a process for generation of hydrogen and syngas based on biomimetic carbonation and photocatalysis. A path breaking way has been developed for generation of solar fuels in specific hydrogen by coupling biomimetic carbonation with photocatalysis. Efforts are being made worldwide to mimic the reaction for fixation of anthropogenic CO2 into calcium carbonate using carbonic anhydrase (CA) as a biocatalyst. CA is being employed to accelerate the rate of hydration of CO2 to form carbonate ions and proton. Presently carbonate is being precipitated from aqueous solution as calcium carbonate given a suitable saturation of calcium and carbonate ions by addition of appropriate buffer. A major breakthrough in the area of generation of solar fuels like hydrogen has been achieved by coupling biomimetic carbonation with photocatalysis. This approach may prove to be a revolutionary technical advancement required for hydrogen economy demanding carbon neutral hydrogen production. Also the production of hydrogen in addition to carbonates as end products during biomimetic carbonation may make the process commercially viable to be adopted by industries emitting carbon dioxide. The carbonate rich stream has been photocatalytically reduced to formaldehyde. This breakthrough thus opens new horizons in the area of carbon sequestration by virtue of the fact that end product of carbon sequestration is not only environmentally benign product of calcite but it would lead to the generation of clean energy including hydrogen, methane and methanol. Maximum hydrogen evolution has been observed upto 101.14 µmoles/mg of ,free CA , 156.8 µmoles/mg of immobilsed CA and 101.14 µmoles/mg of CA 6684.5 µmoles/mg of stabilised CA using TiO2/Zn/Pt as photocatalyst. The problem of using Zn as a metal donor has been overcome by illuminating the system. Hydrogen evolution to the tune of 84 µmoles/mg of CA has been observed for system with Zn as metal donor in the presence of Pt as co-catalyst with illumination.