What are the 2 methods used to manufacture ethanol? What are the advantages and disadvantages of both?
The hydration of ethene: Ethene and steam are passed over a catalyst - concentrated phosphoric acid (H3PO4) - at 300OC and 60-70 atmospheres. This process is fast, continuous and gives a pure product but it requires ethene, produced from cracking, and high temperatures and pressures and is therefore non-renewable and expensive.Fermentation of sugars: Yeast is added to a sugar or starch solution and left for several days in warm, anaerobic conditions, inducing anaerobic respiration of yeast which leads to the reaction: Sugar -> Ethanol + Water. This process is slow as it is a batch process which takes several days, and produces impure ethanol. However less energy is needed and the resources required - such as maize or corn - are cheap and renewable
