How Methanol is Produced?
Methanol, also known as methyl alcohol or wood spirit, is the simplest (shortest chain) of alcohols. It consists of one part carbon, one part oxygen, and four parts hydrogen.
Commercially, methanol is commonly produced from coal, natural gas, and other renewable sources such as recycled carbon dioxide, biomass, and municipal waste. Initially, it was produced by destructive distillation of wood, but nowadays it is produced from synthesis gas by combining hydrogen and carbon monoxide with the help of a catalyst.
In addition to that, small amounts of methanol are produced during the process of alcohol distillation. It is produced at the initial stages and discarded by the distillers. This biodegradable form of alcohol is an organic water-soluble chemical.
How to Minimize Methanol in Fermentation?
During the fermentation stage of alcohol production, methanol is produced.
The amount produced varies depending on different conditions, including temperature, type of yeast and other bacteria in the solution, the type of food provided, minerals, and more.
Normal fermentation of starch-derived sugars from corn, wheat, and barley will only contain very small amounts of compounds that can turn into methanol during fermentation.
ACE Alcohol Copper Distillation Equipment
Can You Test for Methanol in Alcohol?
Yes! You can test for the presence of methanol in an alcoholic beverage by performing some quick tests.
The Smell Test
Smelling the beverage is the easiest methanol test, but it takes practice to sharpen your senses. If you detect an unpleasant chemical odor, the drink is not safe for consumption.
Methanol has a sharp, stinging scent that is quite potent and can be easily recognized as “the smell of alcohol”.
Ethanol will have a much milder smell in comparison. It is softer, less pungent, and almost has a “creamy” aroma. Ethanol does not smell as strong as methanol of the same concentration.
Compared to methanol, ethanol has a very pleasant smell, but it is difficult to distinguish if you’re not comparing the two side by side.
The Flame Test
Take a small sample of the alcohol solution and ignite it. If you observe a yellow flame instead of a blue flame, the solution contains methanol.
Again, this test is good in theory, but in practice, you will seldom encounter solutions that are entirely methanol or ethanol. They are usually blended and of varying proportions.
Also, be extremely cautious when using fire as distilling can be a potentially explosive process. Keep any open flames well away from the still.
The Chemical Test
A more effective test for methanol in alcohol is to apply sodium dichromate to a small sample of the solution.
To perform this test, mix 8 mL of sodium dichromate with 4 mL of sulfuric acid. Swirl the mixture and add 10 drops of it to a small container or test tube containing the alcohol to be tested.
Gently swirl the test tube and use your hand to fan the air from the opening of the test tube towards your nose while holding the tube 10-12 inches away. Notice the smell – if it is unpleasant and pungent, then the alcohol contains methanol. However, if it smells fruity, the beverage contains only ethanol and is safe for consumption.
How to Avoid Methanol in Distilling by Making “Cuts”?
This is where the magic happens.
Depending on the varying boiling points of different chemicals involved in distillation, the process allows you to collect those chemicals separately.
Lighter compounds with lower boiling points will evaporate first, while heavier compounds with higher boiling points will evaporate last.
Regular distillation (or pot distillation) allows for a crude separation of compounds.
Fractional distillation using a reflux still enables you to separate the compounds much more accurately.
By making “cuts,” you collect the distillate from your still in discrete containers. You switch between containers at regular intervals (e.g., every 200 mL) to separate the output into four stages – foreshots, heads, hearts, and tails.
During distillation, you must collect the distillate in many separate glass containers as the flavor and contents of the alcohol solution change throughout the process.
The foreshots, which contain mainly acetone (ethyl acetate), methanol, and other poisonous elements, come out before the vapor temperature reaches 175 degrees Fahrenheit. This part is highly toxic and has an awful taste, so it must be discarded. Foreshots contain almost zero ethanol.
It is recommended to collect and discard around 4 ounces of foreshots per 5 gallons of distillate. However, this is the minimum recommendation, and you can always discard a little more. If using a reflux still, it is best to discard the initial 50 mL you collect; if using a pot still, discard 100-200 mL. This ensures that all the methanol and other harmful foreshots are removed.
The next stage is the heads, which come out at 175-185 degrees Fahrenheit. The heads can be set aside but can also be recycled, as they may contain substances that can affect the flavor of the final beverage. There will be a small amount of methanol mixed with ethanol, and the delineation is very gradual.
The hearts, mainly containing ethanol, evaporate at 173 degrees Fahrenheit (78.3 degrees Celsius). The majority of the distillate collected will be heads.
If not separated in time, the unwanted bitterness and oily aroma from the tails could dominate the final product. The tails come off at approximately 203 degrees Fahrenheit (95 degrees Celsius) and should be removed from the distillate.
Tails can be collected and recycled to extract more ethanol in the next distillation run.
