The chemical industry plays a pivotal role in many sectors, from agriculture to healthcare, and energy to manufacturing. Chemicals, particularly petrochemicals, are used as starting materials for many consumer products such as plastics, textiles, fertilisers, cosmetics and cleaning products.

The nature of chemical production makes the chemical industry a significant emitter of carbon dioxide (CO₂), primarily due to the energy-intensive processes involved, and the use of fossil fuels as feedstocks. According to the International Energy Agency, direct CO₂ emissions from chemical production amounted to 925 Mt in 2021, a 5% increase from the previous year. The chemical sector is now the third largest producer of direct CO₂ emissions. As demand for consumer products continues to grow, so too are concerns about the impact of the chemical industry on the environment and human health.

To reduce the adverse effects of using petroleum-based products and their derivatives, researchers are turning to chemicals made from renewable sources such as wood, algae and agricultural waste. Renewable materials produce fewer greenhouse gas emissions during their life cycle, making them more sustainable in the long term compared to fossil-based resources. In addition, some renewable feedstocks are otherwise regarded as waste. In this case, their use contributes to waste reduction, and contributes to a circular economy.

Amine production

In the lab of Professor Yan Ning from NUS Chemical and Biomolecular Engineering, his team is exploring a pathway to convert lignin, a wood component, into renewable organonitrogen chemicals like amines. Amines are found in many products, from small molecules like ethanolamine, which is used for CO₂ absorption, to larger synthetic polymers like nylon, an essential material in the fabric industry.

The current industrial processes for manufacturing amines rely heavily on non-renewable fossil resources, resulting in the production of large amounts of chemical waste, the need for harsh reaction conditions, use of highly toxic or hazardous intermediates, and relatively low product yields. There have been limited efforts in synthesising amines from renewable sources. According to Prof Yan, the few existing renewable pathways to organonitrogen chemicals have not been established or are inefficient, characterised by their lengthy processes and low efficiency. His objectives are to develop innovative strategies for the production of organonitrogen chemicals, by either formulating novel pathways or enhancing the effectiveness of existing procedures.

Utilising by-products

By working on lignin, a renewable feedstock alternative, Prof Yan hopes he can contribute to a more sustainable chemical industry. Lignin is an organic polymer that is abundant in plant cell walls. It is a major by-product of the paper industry and agricultural waste, and at present, is mostly burned for energy, which is a low-value, waste-generating application. 

As lignin has a complex chemical structure, the aim is to break down the polymer into simpler and smaller constituent parts, referred to as monomers. These monomers can then be converted into other chemicals. For instance, lignin can be used to synthesise phenol, a chemical that is used in resins and plastics, offering a sustainable alternative to petroleum-derived phenols.

Prof Yan next aims to investigate the production of amines from chitin, a crucial component in the shells of crabs, shrimp, lobsters, and the exoskeletons of insects. Following this he will turn his attention to nitrogen gas as a nitrogen source for amine production, a feat that has yet to be achieved.

With the push for sustainable practices, and a circular economy, growing stronger, the chemical industry will likely turn to a wider range of renewable sources for chemical production. Already animal fat and used cooking oils have been used to produce bio-based diesel. The chemical industry is an important contributor to many sectors, including agriculture, healthcare, manufacturing, and energy. By turning to renewable sources, the industry can continue to positively impact our lives while safeguarding the planet for future generations.