Peak oil theory suggests petroleum is limited and will run out. Petroleum comes from decaying organic matter that has been heated and pressurized for a very long time. Here, time is an unattainable resource and therefore limits natural petroleum production. Abiogenic petroleum theories may say otherwise, but there’s also a known cost-effective way to produce synthetic petroleum!
There are four groups of organic chemicals which comprise petroleum. There are alkanes which comprise, on average, 30% of extracted petroleum, cycloalkanes which comprise 49%, aromatic C5/C9 resins which comprise 15%, and asphaltenes which comprise 6%. The alkanes, also known as paraffins, are your natural gases: things like methane, ethane, propane, and butane. The cycloalkanes, also known as naphthenes, make up a large part of fuels and white-out. The resins are used for varnishes, adhesives, and food glazing agents much like other resins from plants. And finally, the asphaltenes, which are solid particulates, act as binders. They’re used for concrete road, shingles, and waterproofing buildings. Cement and epoxy are some commonly known binders.
The most important parts are the alkanes, cycloalkanes, and to a lesser degree: the aromatic resins. Gasoline is comprised of all these three things because it comes from distillation of petroleum. Mineral oil, which is just refined crude oil, comes in three flavors: Paraffinic, Napthenic, and Aromatic.
There are two main processes used to make synthetic petroleum. The first, which was invented in 1925 and used by Germans in WW2, is known as the Fischer-Tropsch process [ (2n + 1)H2 + nCO → CnH(2n+2) + nH2O ]. Depending on the ratio of hydrogen gas and carbon monoxide, you can engineer any alkane that you’d like. Hydrogen and carbon are wildly abundant too. Carbon monoxide is easily enough to derive as well. You could heat carbon in air to get carbon dioxide and then increase the temperature until carbon monoxide is the more stable phase, you could pass steam over carbon, you could find a natural occurrence, you could do a variety of things to get it. Any natural gas can be engineered in an economically efficient fashion.
The second process, or rather a collection of processes, is known as catalytic reforming. Ironically, it’s already used extensively in the petroleum industry. In real simple terms, it means using catalysts to rearrange stuff on organic molecules. Catalysts can be anything from metals, oxides, or even enzymes. It’s their unique properties that allow us to rearrange stuff on organic molecules. Here are a few specific processes that are useful to our goal of synthetic petroleum:
Alkanes, in the presence of a platinum catalyst, will rearrange to form isoalkanes and branched alkanes (which can be volatile at room temperature and pressure, be careful!). The isoalkanes can then be separated will typical wet chemistry techniques.
With those isoalkanes, we can reuse that same platinum catalyst to form cycloalkanes. You see, although platinum is expensive, it can be reused over and over again because it’s not actually consumed in the reaction.
Finally, we can use the cycloalkanes in the presence of hydrogenation acceptors (such as sulfur, selenium, or 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone) to aromatize it. Odd numbered carbon cycloalkanes are a bit trickier to work with, but all you need to do is an R group to stabilize the molecule. An R group is simply a side chain and can be anything from oxygen, cyanide, or even molecules more complex than our current product. For our purposes though, we’d use simple ones.
Asphaltene is a large group of complex molecules. However, these molecules aren’t necessary for gas and oil, and it’s easy enough to engineer any kind of binder that we’d like for the specific application.
Anthony's Musings 