Turning Fruits Into Refrigerant

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In keeping with the theme of my last two videos, I decided to try another chemistry project involving fermentation. In this video, I'll be fermenting a mix of apples, bananas, grapes and strawberries into ethanol. The ethanol produced by this method is at a pretty low concentration and it's mixed with lots of undesirable organic compounds, so it's distilled to purify it. A second distillation is done with a fractional distillation column, which brings the output concentration to around 75%. The ethanol is then converted to low-temperature refrigerant by two different methods:

In the first method, ethanol vapor will be dehydrated by an aluminum oxide catalyst at 350C to convert it into Ethylene (C2H4) and Water. The water is condensed out, and the Ethylene gas is dried, and then compressed to around 20 bar in a heat exchanger connected to the evaporator of a refrigeration system running somewhere between -30C to -40C. At this temperature and pressure, the Ethylene liquefies, and when it's discharged to the atmosphere, it's forced to evaporate, dropping its temperature to the boiling point of -104C. I stupidly did this without gloves, and actually gave myself frostbite on the tip of one of my fingers.

In the second method, the ethanol is diluted with water to a concentration of about 6% ABV. Then, a small amount of unpasturized apple cider vinegar is introduced into the solution. The bacteria in the unpasturized vinegar ("acetobacter") consume ethanol and oxygen and output acetic acid. Normally this process takes 6-8 weeks, but with a bubbler aerating the solution 24/7, I was able to get measurable results within about 10 days.

Once the acetic acid has been produced, it's reacted with baking soda to form sodium acetate. The sodium acetate is electrolyzed with a platinum anode, producing a combination of CO2 and Ethane (C2H6). To isolate the Ethane from the CO2, the gas mix would need to react with Calcium Hydroxide, but I didn't go that far in this video.

The boiling point of Ethylene is -104C and Ethane is -89C, which means both of these gases are commonly used as the second stage refrigerant in a cascade vapor-compression system. They're also used in the gas mixtures of mixed-gas joule-thomson cryocoolers for liquefying natural gas or nitrogen.

It is possible to make a first-stage refrigerant with fruits by the dimerization of Ethylene to Butene, but this requires high temperatures and pressures with an exotic catalyst to perform the reaction. Butene (C4H8) has a boiling point of around -6C, which would make its performance similar to R600A (isobutane) in small, low-power refrigeration systems like tabletop icemakers or mini-fridges.