With the right catalyst, we can make jet fuel from carbon dioxide

Techniques for capturing carbon dioxide in the atmosphere2 And turning it into a fuel provides a climate-friendly alternative to exploiting fossil fuels – they might release carbon dioxide2 Back in the air on combustion, but no net change. This includes biofuel crops, but can extend to industrial processes that directly involve carbon dioxide2. As processes that capture carbon dioxide2 From ambient air becomes more economical, as does the potential value of that CO2 As a supplier of fuel.

There are several methods you can take to create fuel, but they are energy-intensive because of the carbon dioxide2 It is a stable molecule – reversing the combustion reaction to produce new fuel does not happen for free. But there is an additional challenge: designing a process that is precisely tuned for production Type Of the fuel you want.

One way to do this is to use a catalyst – a substance that directs chemical reactions without consuming it. With the help of a single catalyst, carbon dioxide was captured2 In addition to hydrogen gas, it may convert primarily to methane; A different catalyst may shift the primary product towards the larger molecules of the liquid fuel.

A new study led by Benzene Yao from the University of Oxford describes a new catalyst that has led to the production of long-chain hydrocarbons used in jet fuels.

Numbers

This catalyst is iron – manganese – potassium – nothing too strange. In the tests, only five percent of the converted carbon dioxide2 Carbon monoxide and 10 percent ended up as methane, while roughly half of it converted to long-chain hydrocarbons in the jet fuel range (8-16 carbon). Compared to other catalysts tested in previous studies, this is a much better outcome in the aviation fuel range. Of the 2-4 carbon hydrocarbons produced, they are preferred Alkenes On Alkanes, Which means more carbon-carbon bonds and fewer carbon and hydrogen bonds. The reaction produces five times as much propylene as propane, for example. These are useful raw materials for things like plastic.

The catalyst provides sites for hosting feedback, which affects the product. Here, this mainly happens to the iron and carbon metal that is converted to and from iron oxide. One form helps CO2 The molecules interact with hydrogen, while the other helps the resulting carbon monoxide molecules interact with hydrogen to build hydrocarbons.

Basic chemistry at work here.
Zoom in / Basic chemistry at work here.

The method for making the catalyst turns out to be important. The materials were combined with an organic compound that was burned while everything was kept at 350 ° C for a number of hours. The combustion reaction helps iron, manganese, and potassium form the correct minerals, and leaves some carbon behind. Experiments with a similar catalyst made in a different way were much less effective.

Reset

Although the catalyst is not consumed during use, it changes, which means that it may have to be regenerated at some point. As it was before its first use, it can be done at high temperatures in the presence of hydrogen and carbon monoxide, and remineralisation of the catalyst.

As part of the real world system, this will be linked to the CO2 Capture lab and electrolysis device that splits water to make hydrogen gas. Products can then be separated and processed as needed.

Obviously, this study concerns only an understanding of the type of catalyst to be used, and there is no economic analysis of the fuel production process here. There is a lot of energy input into this process, especially when compared to conventional oil production. But while petroleum fuels add to the carbon dioxide2 In the atmosphere, air-based fuels can add very little (or nothing depending on the power source required). This also comes with the option to break down the types of hydrocarbons they manufacture, rather than just working with whatever comes out of the ground.

Nature Communications, 2020. DOI: 10.1038 / s41467-020-20214-z (About DOIs).

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