From Christmas trees to rubber latex

Sheffield, UK – Pine needles from discarded Christmas trees or other sources could be turned into renewable fuels and new products research at the University of Sheffield and the University of Valladolid have found.

According to a release from the universities’, their researchers have identified an ‘efficient, water-based’ process for producing formic acid from pine needles to replace less sustainable chemicals.

Potential applications for the recovered formic acid include renewable fuels, food preservatives and coagulants for the production of dry rubber from natural rubber latex, the statement issued 29 Dec 2022 further pointed out.

The work builds on an earlier study, which showed that pine needles could be chemically broken down into a ‘bio-oil’ for use in the production of sweeteners, paint, adhesives and vinegar, as well as bio-char for use in other industrial chemical processes.

When reacting carbon dioxide to capture CO2 involves the use of a metal to promote the reaction, noted Dr James McGregor, senior lecturer in the department of chemical and biological engineering at the University of Sheffield

“This can be inefficient and expensive, so we went back to some of the work we’ve done previously with pine needles, because we realised that we could potentially use these to promote turning the carbon dioxide into formic acid,” explained McGregor.

University of Valladolid PhD student Maria Andérez-Fernández added: “We found that instead of the metal and the carbon dioxide reacting, we could react carbon dioxide with pine needles and water at high temperatures and a fraction of the pine needles would turn into the same product as the CO2.

Carbon dioxide is introduced as sodium bicarbonate and the co-conversion with captured carbon dioxide, she explained, enhance the conversion of each other, making it more efficient and in this case, making more of the end product - formic acid.

 “With these results, this study sets a new strategy for CO2 and residual biomass valorisation to produce renewable fuels and value-added chemicals, using only water as a solvent and producing a simultaneous reaction that simplifies the process and makes it more efficient,” said Andérez-Fernández.

The study also looked at using other waste materials and concluded that refineries could use mixed biomass feedstock at different times of the year when different waste products are more abundant, for example, using pine needles in January.

This, however, could create a challenge in the process design, as currently refineries use feedstock that is constant throughout the year.

So, if what you are feeding in as your reactants change throughout the year, this would have to be built in, admitted McGregor.

“But it’s a place we would like to get to so that in January, we are using the millions of pine needles readily available rather than them going to landfill,” he stated.

According to the release some 7 million Christmas trees end up in landfill in the UK each year, releasing an estimated 100,000 tonnes of harmful greenhouse gases into the atmosphere.