Introduction to Ethanol and its Production

Ethanol, in the past months has become a major issue of discussion among scientists and governments for many reasons. In the blog posts to come I will be talking about ethanol, its production, uses and potential advantages and disadvantages to using as ethanol as an alternative fuel source in cars.

Products made from crude oil.

Most of the ethanol we use to day is made through the industrial process. It is made my adding a water molecule to an ethylene molecule. Ethylene is an alkane produced from the distillation of crude oil. Crude oil is the base liquid for many of the things we use to maintain a normal lifestyle, these include: plastics, fuel for cars buses and planes, lubricants, kerosene and many other products. There is only problem with crude oil; it is a non-renewable resource. Crude oil is made over millions of years through the fossilisation of dead organic matter. Once we have used all crude oil, there will be no way to produce petrol for cars and make plastics for bags. This is one of the main reasons an alternative fuel source for cars is needed. Scientists have found this alternative fuel source in the form of ethanol.
Their are two names for ethanol depending on the process through which they were made. These are conventional ethanol and cellulosic ethanol. The latter is the process though which I'll be explaining the production of ethanol.

A flowchart of the production of ethanol from 3
different processes.

Cellulosic ethanol is the ethanol produced from a wide variety of different biomasses through chemical processes. This process starts with cellulose. Cellulose is a condensation polymer, meaning that it is made up thousands of individual molecules, in this case, a simple sugar called glucose. From glucose we are able to produce ethanol. To get from glucose to ethanol, a process called fermentation is used. Fermentation is used in many industries, from the biochemical to the tea industry. This process involves the use of yeast and/or different bacteria to transform a sugar into an alcohol. The overall chemistry of fermentation is fairly simple but the actual process is very complicated needing a different enzyme for each step. Here is a simple chemical equation of the fermentation of glucose to produce ethanol with Carbon dioxide as a by product, along with a link to website that explains the many different types of fermentation and its uses.
                  
                                        Glucose ----------> Ethanol   +  Carbon Dioxide
                                                    Yeast catalyst
                                         C₆H₁₂O₆      →        2 C₂H₅OH  +        2 CO₂
                  
                                    http://www.wisegeek.com/what-is-fermentation.htm

The only problem with Cellulosic Ethanol is that scientists have not yet found a simple, efficient and economical way to break down cellulose into its individual molecules of glucose.

Ethanol can now be used as an alternative fuel for cars but i will talk more about that in the next blog post. Ethylene which is the raw material for plastic and and other manufacturing can then be gained through the dehydration process of ethanol. This involves a catalyst (usually concentrated sulphuric acid) and involves removing a water molecule from the ethanol molecule. The chemical equation of the dehydration of ethanol to ethylene is shown below.

                                         Ethanol ----------> Ethylene + Water
                                                    
                                                   Conc. Sulfuric acid
                                            CH₃CH₂OH_(l)    →     C₂H_{4(g)  +} H₂O_(g)