After fermentation acetic acid is chemically converted to an alcohol.
Converting Acetic Acid to Ethanol
The resulting acetic acid from the fermentation process is converted to an intermediate product–ethyl acetate–and then reacted with hydrogen to make an alcohol. With this process, the alcohol produced is ethanol. The needed hydrogen can be produced in a variety of ways and we are investigating steam reforming in this project. Another method, gasification, may be more important for commercial scale production.
In this method, steam and natural gas are combined at elevated temperature and pressure to produce hydrogen. This technology is well developed and efficient so that natural gas usage is minimized. It is also the most common way to produce hydrogen industrially today.
In this process, the hydrogen is created using high temperatures to gasify the poplar lignin residues produced during pre-treatment. By combining the fermentation process with gasification about 2/3 of the energy in the alcohol comes from the sugar stream and 1/3 comes from the lignin stream in the form of hydrogen.