Electronics

Citrus peel provides an alternative route to bio-based PEF plastics

Sari Rautiainen, Senior Scientist at VTT, proposes a new circular approach to PEF plastics. From citrus peels to PET bottles.

Fossil-based polyethylene terephthalate (PET) plastics are especially widely used in packaging and PET bottles. While plastic has many advantages in food packaging, it also poses major environmental issues, including: Plastic pollution And carbon emissions. To address these issues, fossil-based PET plastics can be replaced with bio-based polyethylene terephthalate (PEF) plastics, which emit less carbon dioxide. However, this shift requires a new and efficient method. Created by VTT An alternative route for producing PEF plastic from food waste streams. Roundness and high yield are the main advantages of this new technology.

Our current practice of using, consuming and disposing of plastic poses significant global challenges and damage to our environment. Addressing these issues requires new and sustainable solutions and technologies.

Plastic packaging is one of the most urgent areas for the transition to more sustainable solutions. Both environmentally friendly consumers and policy makers want more sustainable packaging. The EU strategy focuses on achieving 100% recyclability, reusability, or compostability of packaging materials by 2030.

Shift to bio-based materials

VTT has identified the transition from sustainable raw materials to bio-based materials made as one of the major paths to a circular economy in plastic packaging. Currently, most plastic packaging materials are made from fossil raw materials, and these materials are not normally distributed.

Replacing these fossil-based materials with alternative bio-based materials made from renewable raw materials can significantly reduce carbon dioxide emissions in packages. These bio-based materials can take the circular economy of packaging to a new level, along with solutions that enable effective recycling and increase biodegradability.

PEF – 100% bio-based alternative to PET plastic

Research is being conducted on the potential for producing bio-based PET plastics, but there are no commercially viable results. PEF plastic is a 100% bio-based alternative to PET plastic with enhanced properties.

Replacing fossil-based PET with plant-based PEF polymers can reduce carbon dioxide emissions in final products by 50%. PEF also offers excellent mechanical and barrier properties. When applied to food packaging, this means a longer shelf life for food.

Traditionally, PEF plastics are made from edible glucose and fructose. VTT’s new technology provides a cyclical approach. It uses a stream of food waste as a raw material for making PEF plastics.

FDCA: Essential component of PEF plastic

PET plastics use terephthalic acid in the production of polyesters, which PEF plastics replace with bio-based 2,5-furandicarboxylic acid (FDCA) and its esters. In addition to terephthalic acid, both PET and PEF require ethylene glycol as the second monomer that can be produced from renewable resources.

Traditionally, FDCA is manufactured in a two-step process starting with edible glucose and fructose, with 5-hydroxymethylfurfural (HMF) as an intermediate. The sugar is first dehydrated using an acid catalyst to 5-hydroxymethylfurfural (HMF) and then oxidized to FDCA. Another option is to use methanol as the solvent for dehydration and produce methoxymethylfurfural (MMF) as an intermediate.

There are two issues related to this common method. First, the raw materials glucose and fructose can also be used in the food industry. Therefore, this process directly competes with the food chain. This problem can be overcome by using lignocellulosic glucose.

The second issue is related to HMF instability. This intermediate reacts more easily under acidic conditions to produce levulinic acid and insoluble humin. Due to this instability, HMF yields often remain low. Great efforts have been made to suppress side reactions and enable high yields of isolated HMF, but the inherent instability of HMF makes it a challenging molecule for biorefinery. I will.

VTT’s new route to FDCA

VTT’s chemical development platform has created a unique and highly efficient process for producing FDCA and its esters. This patented technology overcomes the challenges associated with FDCA’s traditional manufacturing process.

This will allow the flow of agricultural waste, including pectin, to be used as a raw material, strengthening the plastic circular economy. In addition, C6 aldaric acid is used as a stable intermediate. Stable intermediates do not tend to react any further, which is essential for achieving high yields of FDCA.

The first step in this new route is to replace edible glucose and fructose with sustainable ingredients that do not compete with the food industry. The VTT process uses a stream of food waste such as orange peel and beet pulp as a raw material. VTT’s biotechnology experts have developed and patented a technology to produce aldaric acid by oxidizing galacturonic acid, the main component of pectin. This technology allows underutilized waste carbohydrates to be used as a source of renewable monomers.

Aldaric acid is a stable intermediate for the production of FDCA. The next step in the process is the dehydration of aldaric acid catalyzed by a solid acid in butanol or other alcoholic solvents to produce furancarboxylates. Best results are achieved with heterogeneous acid catalysts such as sulfonic acid catalysts supported on silica. The FDCA monoesters and diesters produced by this process are easier to process than FDCA in the form of free acids.

VTT can solve the entire route from food waste to PEF plastics by combining VTT’s patented technology for producing aldaric acid from pectin, followed by technology for producing FDCA from aldaric acid. This efficient process enables high yields of up to 80 mol% of FDCA.

Suitable for high-end applications

The PET market is currently over 30 million tons per year. The main fields of application are food packaging, PET bottles and textiles. PEF polymers can directly replace the raw materials of these plastics, reducing carbon dioxide emissions in the final product by 50%. In addition, PEF is a high performance plastic, which has improved quality compared to PET plastic and mainly has excellent barrier properties. PEF provides a barrier that is several times better than PET for oxygen, carbon dioxide, and water. The use of this material in food packaging extends the shelf life of food and helps reduce food waste.

© iStock / narcisa

PEF is fully renewable and fully recyclable. PEF bottles can be recycled directly on the PET stream. This is important for consumers as these products enter the market. This opens up the possibility for the industry to reduce waste and have a positive impact on the environment.

PEF can provide a direct replacement for PET plastic, but PEF is not the only one that can benefit from FDCA. FDCA is also rapidly gaining interest as a bio-based monomer for other applications such as polyurethanes and epoxies, and research into other materials is ongoing.

Next step: Expand production

VTT has introduced this process for producing FDCA from food waste to pilot production. Production is on a kiloscale and is still expanding. VTT’s unique scale-up infrastructure from laboratory to pilot ensures that this new technology reaches a technology readiness level that allows polymer manufacturers to easily transition to full scale.

Currently, VTT is looking for an industrial partner to expand its production. In the near future, you may buy orange juice in a bottle made of orange peel.

Please note that this article will also be published in the 6th edition. Quarterly magazine..

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