Acrylic Acid: The Building Block of Plastics Industry

 
Acrylic Acid 

Acrylic acid, also known as propenoic acid, is an important unsaturated carboxylic acid used primarily as a monomer in the production of polymers and co-polymers. It is a colorless, volatile liquid with a characteristic acrid odor and finds widespread applications in the plastics, coatings, adhesives and hygiene industries.

 

Manufacturing of Acrylic Acid

Acrylic acid is produced commercially through a two-step process - oxidation of propene to acrylonitrile followed by hydrolysis of acrylonitrile to acrylic acid. Around 70-80% of acrylic acid is produced via this route.

Oxidation of propene:
In the first step, propene is oxidized to acrylonitrile in the presence of a catalyst. This catalytic oxidation is conducted at 200-400°C using air or oxygen and yields acrylonitrile in around 95% selectivity. The major catalyst used is a cobalt-based caatalyst optionally promoted with bromine or molybdenum.

Hydrolysis of acrylonitrile:
In the second step, acrylonitrile obtained from the above reaction is hydrolyzed to acrylic acid. This hydrolysis is conducted by blowing steam into acrylonitrile at 150-200°C in the presence of sulfuric or phosphoric acid as a catalyst. The reaction yields acrylic acid in nearly 100% yield.

Alternative production methods:
Other methods for acrylic acid production include hydrocarbon oxidation, carbonylation of ethylene and oxidation of propylene. However, the most economical and predominant route is the two-step oxidation-hydrolysis process from propene.

Properties and Applications

Acrylic acid is a colorless liquid with a boiling point of 141°C and melting point of 13.6°C. It polymerizes easily and hence is usually stabilized during storage and transportation using inhibitors like hydroquinone. Some key properties and applications of acrylic acid are:

Superabsorbent Polymers:
Polyacrylic acid and its salts like sodium polyacrylate are superabsorbent polymers used extensively in baby diapers and adult incontinence products to absorb large volumes of aqueous fluids.

Adhesives:
Acrylic acid based polymers and copolymers find extensive application as acrylic pressure sensitive adhesives, hot melts, construction adhesives due to their excellent adhesion to various substrates.

Coatings:
Acrylic acid is polymerized to form acrylic resins which are used as exterior architectural coatings and interior decorative paints owing to properties like transparency, weather resistance, color retention.

Hygiene Products:
In addition to use in superabsorbents, acrylic acid derived polymers are present in many personal hygiene products like cotton fibers, tissue papers, wet wipes etc. for attributes like softness, bulk.

Thickeners and Emulsifiers:
Various acrylic polymers and copolymers are employed as thickeners, emulsion stabilizers and rheology modifiers in cosmetics, pharmaceuticals and food formulations.

Others:
Some other minor applications of acrylic acid include fiber production, production of acrylate esters for surface coatings and water treatment polymers.

Environmental and Safety Aspects

Being volatile and highly reactive in nature, few safety and environmental issues need to be addressed during production, transportation and downstream processing of acrylic acid:

- Acrylic acid is highly flammable with a flash point of 32°C. Special precautions need to be taken against fire and explosions risks especially during catalytic oxidation reaction.

- Due to its acrid odor even at low concentrations, acrylic acid production and processing units require proper ventilation and exhaust systems to limit worker exposure.

- Spills of acrylic acid into water bodies can lower dissolved oxygen levels and impact aquatic life. Its polymers have triggered concerns about microplastic pollution.

- Waste streams from acrylic acid plants need treatment to remove organic contaminants before being discharged/incinerated to meet environmental regulations.

- Proper handling and storage in inhibitor-stabilized conditions is necessary to prevent polymerization of this highly reactive chemical.

- Use of green chemistry principles like development of bromine-free catalyst systems can help address certain environmental issues related to acrylic acid production.


In summary, acrylic acid is a basic petrochemical building block consumed on a large scale worldwide in the synthesis of superabsorbent polymers, adhesives, coatings and other acrylic derived products. While endowed with many useful properties, its flammable and hazardous nature demands compliance to safety and environmental standards throughout its lifecycle to ensure sustainable production and applications of this industriall

 

Get more insights on this topic: https://www.ukwebwire.com/linear-motion-system-market-industry-insightstrendslinear-motion-system-market-2/

 

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