Advanced Cryogenics' Sam A. Rushing explores the subject of CO2 industrial applications, primarily relating to organic and inorganic chemical usage in industry.

Carbon dioxide has been at the forefront of much of today’s media, as a major greenhouse gas which will be an extraordinary challenge to manage in the future.

The greenhouse effect, that being the rise in global temperatures, sea levels, and other catastrophic effects, is one of the most daunting challenges ahead – even though so many schemes for sequestration have been identified, these are yet to be proven.

This article is specifically written on the subject of CO2 industrial applications, primarily relating to organic and inorganic chemical usage in industry.

This chemical industry application, which can include chemical feedstock applications for CO2, is a smaller part of the greater applications in the merchant trade.

As I have written in the past, in the developed markets some 70% of the merchant CO2 is dedicated to food & beverage usage, for the most part. The remaining 30% is then dedicated to a wide range of industrial applications, including chemical manufacturing, both organic and inorganic feedstock requirements for CO2.

Of course, there can be niche, pipeline-fed destinations for carbon dioxide which are ‘over the fence’ – perhaps a chemical manufacturing application, or via a more distant pipeline such as enhanced oil recovery (EOR), which create a base load or full load for a plant site.

Production of calcium carbonate from slaked lime, via CO2 injection, is common in the commodity chemicals realm.

Captive utilisation of CO2
I can think of many applications for CO2 in industry to include both inorganic and organic in some fashion or form; beyond the large volumes and wide variety in the food processing industry (freezing, cooling, and gas packaging), and of course beverage carbonation.

When taking out welding gas usage, metallurgical and allied applications, plus fire abatement, supercritical extraction, oil and gas (enhanced production and well stimulation), carbonic acid production for Ph reduction, laser applications, and pneumatic applications, the following paragraphs describe what I generally think of in terms of organic and inorganic related applications for CO2.

From an old chemical industry perspective, soda ash or sodium carbonate plants such as Church & Dwight and FMC in Green River Wyoming, in the US for example, use CO2 from a merchant Green River plant in the production of sodium bicarbonate or baking soda.

The Church & Dwight plant has been supplied via pipeline from a local merchant CO2 facility.

Other sodium carbonate plants are using CO2 for sodium bicarbonate production in Old Fort, Ohio, which has been supplied via truck or rail delivered. Since much of this sodium bicarbonate must meet certain food/pharmaceutical applications, a food grade, refined CO2 is used rather than using a raw gas product without purification.

CO2 also has applications elsewhere in the production of various commodity products in industry, for example in the plastics industry, where CO2 can be combined with epoxides to create polymers and plastics.

As for commodity organic chemical products, there are a couple of examples too. Methanol production can be enhanced by CO2 injection, whereby CO2 can be injected into a syngas (from reformed natural gas and via catalytic reaction) to yield an increased volume of crude methanol.

If delivering CO2 via pipeline to such a process, this can be considered a captive market as well, while other possible captive markets include the production of urea - where normally the conventional urea manufacturing operation is within an anhydrous ammonia production operation.

The CO2 by-product from anhydrous ammonia production is then used in a two-step process, which would yield the intermediate ammonium carbamate and then dehydrate to a commercial urea.

In some cases, if the anhydrous ammonia plant is not available with the by-product CO2 as a feedstock for urea production on site, then anhydrous ammonia is delivered to a site where CO2 is combined for the production of urea.

This is another possible captive application if large enough, and if delivered via pipeline or other means.

Such applications for the production of urea have taken place in certain world markets, thus transporting both ammonia and CO2 to the manufacturing site for urea production.

Applications in the organic and inorganic realms of chemistry
In terms of other organic-based applications for CO2, these would include the application of raw material for sugar production including polysaccarides (such as starch) and a wide variety of organic compounds for plant growth and their development – including urea once again of course.

In terms of a solvent in industry, the application in dry cleaning operation thus replacing perc is an interesting and environmentally friendly application, moreover, thus replacing and eliminating VOC emissions from an old standard in the form of organic perchlorethylene.

Also, there is the application for CO2 as a solvent for many lipophilic organic compounds, and can be used for removal of caffeine from coffee.

In the pharmaceutical and chemical processing industries, CO2 is becoming more readily accepted these days as a less toxic option to more traditional solvents such as organochlorides – which can be somewhat akin to the replacement of perchlorethylene in the dry cleaning industry.

In the case of certain chemical process and all pharmaceutical industries, the USP standards may be required rather than simply a food grade product.

In the case of USP quality, the major gas companies have a few strategically located plants reserved for the purpose of fulfilling this USP demand; USP grade is essentially of tight record – keeping and reporting for and during the production process.

In terms of agriculture and biological applications, this could be considered organic in general terms, since the plant and animal life is organic by definition in terms of composition.

Plants require CO2 for photosynthesis, and in greenhouse settings, CO2 is often used as a product of fossil fuel combustion, or via merchant product in a gaseous form, which is injected into the greenhouse to enhance growth and quality of the bedding plants, flowers or vegetable production for example.

Today, algae is one of the possible solutions as a raw material for biodiesel production or possibly fermentation with the need to sequester CO2 from power plants currently being evaluated through the application of power plant flue gas in ponds for production of algae.

Summary
As you can see with the above definitions of some CO2 applications in industry, health, and even sequestration, there is a wide range of both organic, and inorganic related applications for this most versatile product.

As the demand for sequestration and more environmentally friendly agents develop, more CO2 will undoubtedly be found in industry.

As noted in this article, sequestration in an organic sense could include applications as an agent for certain algae production options; usually considered for biodiesel production – and this algae can again be a possible feedstock for fermentation as well.

Thus a loop system of sorts emerges.

In terms of environmentally friendly applications, CO2 use can be found in cases such as the replacement of organic halogenated solvents in dry cleaning; plus many more examples.

Once again, CO2 is a remarkably effective and versatile chemical and is again a most daunting greenhouse gas – from a volume perspective, which must be addressed in the term ahead, with respect to global warming and greenhouse gas concerns worldwide.