# Un-cracking petroleum in a refinery **URL:** \ **Category:** Factual Questions\ **Created:** [September 29, 2004, 4:39am UTC](https://boards.straightdope.com/t/un-cracking-petroleum-in-a-refinery/266622 "2004-09-29T04:39:28Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\ **Post date:** [September 29, 2004, 4:39am UTC](https://boards.straightdope.com/t/un-cracking-petroleum-in-a-refinery/266622/1 "2004-09-29T04:39:28Z")
In a refinery, petroleum is fractionally distilled into various species: Natural Gas Gasoline Kerosene Diesel Lubricating Oils Petrolatum, aka petroleum grease Asphalt Often, the heavier fractional species are sent through a reaction chamber under heat, pressure, and catalysis to “crack” the large molecules into smaller, more volatile molecules. These post-reaction by-products are then sent back to be refined again, thus get more valuable gasoline from the heavy oils. Is it possible to “un-crack” natural gas molecules? Build them up into a liquid stock? ---
**Author:** ![bump](https://avatars.discourse-cdn.com/v4/letter/b/7c8e57/32.png) [@bump](https://boards.straightdope.com/u/bump)\ **Post date:** [September 29, 2004, 5:10am UTC](https://boards.straightdope.com/t/un-cracking-petroleum-in-a-refinery/266622/2 "2004-09-29T05:10:30Z")
Absolutely. That’s exactly how synthetic motor oil is made. In a nutshell, they take ethylene gas and polymerize it into molecules called polyalphaolefins, which have most of the characteristics of an ideal oil and then blend that with additives and then you have a much more stable oil for your car. ---
**Author:** ![Roches](https://avatars.discourse-cdn.com/v4/letter/r/bc8723/32.png) [@Roches](https://boards.straightdope.com/u/Roches)\ **Post date:** [September 29, 2004, 6:12am UTC](https://boards.straightdope.com/t/un-cracking-petroleum-in-a-refinery/266622/3 "2004-09-29T06:12:04Z")
Alpha-olefins can also be used to make detergents and other useful products. If I had remembered certain details of the Shell Higher Olefins Process, a method of making linear alpha-olefins from ethylene, at a certain time interval two years ago, I have reason to believe the subsequent time would have been much different for me… Another way of producing heavier molecules from natural gas is by using the methane to make _synthesis gas_, which is mostly carbon monoxide and hydrogen. This can be done done simply by heating the methane to high temperature (~850°) at moderate pressure (~10-20 atm) in the presence of a nickel catalyst. Synthesis gas can then be used to make methanol or ethanol, and it can be used as a feedstock in making other compounds. I don’t imagine that it would be practical to make hydrocarbons from synthesis gas, but it’s not really necessary to do so. Ethanol can be used as a fuel or as a fuel additive, and methanol can be used as a fuel, an additive, or in the manufacture of biodiesel. ---
**Author:** ![Squink](https://avatars.discourse-cdn.com/v4/letter/s/b5e925/32.png) [@Squink](https://boards.straightdope.com/u/Squink)\ **Post date:** [September 29, 2004, 6:26am UTC](https://boards.straightdope.com/t/un-cracking-petroleum-in-a-refinery/266622/4 "2004-09-29T06:26:31Z")
[Making Liquid Fuels From Natural Gas:](http://www.vacets.org/vtic97/qapham.htm) > [@](#): > > methane can be converted to synthesis gas and gasoline can then be produced from this mixture by the Fischer-Tropsch (FT) process. Gasoline is currently produced in Sasol, South Africa and in Malaysia using this technology. Methanol can be produced from synthesis gas using the so called MTG process of Mobil. [How’s your BS Detector? (2002):](http://www.isa.org/InTechTemplate.cfm?Section=InTech&template=/ContentManagement/ContentDisplay.cfm&ContentID=18706) > [@](#): > > Synfuels International Inc. said Monday it has developed a method to convert natural gas directly from a pipeline or wellhead into clean-burning gasoline by way of a cost-effective gas-to-liquids (GTL) process. > … > The Synfuels process differs from the conventional Fischer-Tropsch GTL process in economies of scale and production, he said. Plants using the Synfuels process could vary in size from skid-mounted portable plants to permanent installations – and would be a fraction of the size of a Fischer-Tropsch plant.