Desktop demonstration of the Fischer-Tropsch synthesis

Added: 2026-05-28

[00:00:01]In this video, I will show you how to build a desktop version of the Fischer-Tropsch synthesis and carry out the experiment.

[00:00:09]The Fischer-Tropsch synthesis is a collection of chemical reactions that converts a mixture of carbon monoxide and hydrogen, known as syngas, into liquid hydrocarbons.

[00:00:20]It was discovered in 1925 by the German chemist Franz Fischer and the German-Austrian chemist Hans Tropsch.

[00:00:29]The whole project began with a custom design and construction of a temperature controller for the mini quartz tube furnace.

[00:00:39]Here you can see most of the components of the quartz tube furnace.

[00:00:58]The compression fittings for the quartz tube are made of PTFE.

[00:01:15]The heating element is made of nichrome wire with a diameter of 1 mm.

[00:01:20]The ceramic tube is used for insulation.

[00:01:24]The screw terminal housings are also made of ceramic as they must be heat resistant.

[00:01:30]The quartz tube has an outer diameter of 12 mm and an inner diameter of 8 mm.

[00:01:44]The thermocouple is secured to the ceramic tube with stainless steel cable ties. This allows it to measure approximately the temperature on the inner surface of the quartz tube.

[00:01:55]Finally, the furnace was insulated several layers of ceramic wool to make it easier to read the temperature on the OLED display and operate the rotary encoder. I 3D printed a bracket for the PCB.

[00:02:18]The program I wrote for the temperature controller includes a PID algorithm.

[00:02:24]This is used slowly to set the temperature at the start of the experiment since the reaction itself is strongly exothermic.

[00:02:32]I used these laboratory gas generators to synthesize hydrogen and carbon monoxide. The chemical equations are as follows.

[00:02:44]Next, a stand for the two gas generators was built using 2020 V-slot aluminum profiles and pipe clamps.

[00:02:59]For the mounting blade, I repurposed another polypropylene kitchen cutting board. This time a yellow one measuring 600 by 400 by 20 mm.

[00:03:10]Since I'm German, I over-engineered the stand [clears throat] for the cold trap a bit.

[00:03:16]On the right-hand side, you can see the borosilicate glass tube which has been drawn out into a nozzle and fitted with copper wool to serve as a flashback arrestor. It is used to burn off excess gases since carbon monoxide is highly toxic and like hydrogen forms explosive mixtures with oxygen. I also printed a mounting ring for the vacuum flask which later will be used for the ice salt bath.

[00:03:43]In the next building step, everything was mounted onto the base plate.

[00:04:39]>> The three-way stopcock is needed to flush the apparatus with argon in order to remove all oxygen.

[00:05:07]The dropping funnels are equipped with Bunsen valves. The Bunsen valve is essentially a one-way valve used to stop suck-back problems. It is simple and cheap to make and works very efficiently.

[00:05:25]Next, I connected everything accordingly using silicone tubing.

[00:06:55]>> And this is what the finished Fischer-Tropsch apparatus looks like.

[00:07:06]In preparation for the experiment, the two drying tubes were filled with silica gel.

[00:07:15]Now it was time to make the catalyst. It must always be freshly prepared. Its effectiveness starts to decrease after just a few hours.

[00:07:24]First, 1 g of cobalt nitrate is dissolved in 25 ml of distilled water.

[00:07:36]In the next step, about two teaspoons of silica gel with a mesh size of 140 to 70 are placed in a petri dish. The silica gel particles have a very large surface area and is typically used for column or flash chromatography.

[00:07:53]Using a pipette, the cobalt nitrate solution is dripped onto the silica gel until it cannot longer absorb any more liquid.

[00:08:13]The saturated silica gel is then transferred to a fireproof ceramic dish.

[00:08:20]The material is then calcined using a burner. The following reaction takes place during this process.

[00:08:31]Since nitrogen oxides are produced and cobalt 2-3 oxide is carcinogenic, it is essential to work under a fume hood or outdoors.

[00:08:43]After a few minutes, we are left with silica gel whose best surface area is now covered with cobalt 2-3 oxide.

[00:09:04]To secure the catalyst, ceramic wool was inserted into the quartz tube.

[00:09:21]The catalyst was transferred into the quartz tube using a piece of silicone tube and a funnel.

[00:09:55]>> A cooling bath was then prepared using crushed ice and calcium chloride. The mixture can reach a stable temperature as low as minus 50° C.

[00:10:44]Now it was time to set up the gas generators. Don't worry if you have lost track. I will show you a diagram of the experiment in a minute. It should explain the entire setup.

[00:11:04]Immediately before the experiment, the apparatus was eventually purged with argon.

[00:12:12]>> A few minutes after the experiment had started, the temperature in the quartz tube furnace rose sharply and eventually reached nearly 1,000° C.

[00:12:25]Notice how the pale blue flame slowly turns into a yellow flame.

[00:12:33]That was also the moment when I knew it was working.

[00:12:57]One of the most difficult challenges I faced was keeping the two gas generators running in sync so that they delivered roughly the same amount of gas. I therefore highly recommend using gas cylinders equipped with pressure regulators, needle valves, and flow meters instead.

[00:13:15]In total, I conducted the experiment three times following all the steps described and cleaning the apparatus beforehand.

[00:13:26]When I opened the cold trap the first time, a gasoline-like smell immediately hit my nose.

[00:13:57]This entire yield was then transferred to a test tube, and it turned out that two clearly separated phases had formed.

[00:14:05]The bottom layer consists mostly of water, one of the most reliable indicators of the reaction, even after volatile components have been evaporated.

[00:14:15]And now, what we've all been waiting for, is the top layer, which had a total volume of 2 ml flammable.

[00:14:33]Oh boy, sure it is. What a reward for the more than 200 hours I've spent working on this project.

[00:14:41]Also, sure I don't know what it is.

[00:14:44]Aside from determining the boiling point, I can perform a qualitative chemical detection of aromatic compounds using a Friedel-Crafts alkylation reaction.

[00:14:54]Typically, aromatics react with anhydrous aluminum chloride as a catalyst and chloroform as a solvent to form colored triarylmethane dyes.

[00:15:04]Another option would be the bromine water test for detecting multiple carbon bonds. I might make a follow-up video on this, since I need to order some chemicals for it.

[00:15:19]Thanks for watching. Stay stay true.