Young researchers at the Leibniz Institute for Catalysis, LIKAT, in Rostock have developed a catalytic process for bio-polymers that runs under very mild conditions. The results are building blocks of the plastic PEF, a sustainable alternative to PET beverage packaging. The production of PEF building blocks does not require petroleum, but instead cellulose, i.e. biomass, and essentially only alcohol and air. The process can be transferred into practice immediately. To make it freely accessible, the young chemists published their findings on an open-access platform.
Coca Cola was the first company to build a plant bottle factory in the USA for beverage bottles made of polyethylene terephthalate (PET), which are produced entirely from plant material - but with a high energy input. The conventional process for the PET building blocks requires temperatures of up to 300 degrees Celsius and a pressure of around 100 bar.
In the beginning, we simply took balloons, blew them up in the lab and put them over the apparatus." - Experiment with gas entering the reaction vessel.
"These harsh conditions have so far weakened the industry's enthusiasm for biobased plastics," said Dr. Esteban Meija. He is head of the "Polymer Chemistry and Catalysis" junior research group at LIKAT. The work on the new process was carried out under his leadership.
The result is quasi the "green brother" of PET: PEF, full name: polyethylene furanoate. The PEF process manages with a maximum of 60 degrees Celsius, operates at normal atmospheric pressure and can increase its productivity 15 times over under continuous flow conditions. Dr. Meija: "This makes bio-based polymers such as PEF interesting again for industry.”
Platform Chemical from Rice Straw
The starting material for the PEF building blocks is a so-called platform chemical, a furan derivative called HMF, which is produced from cellulose, a polysaccharide from waste products such as agricultural waste. Laboratories around the world are conducting research on a dozen such platform chemicals in order to convert the raw material for chemistry from crude oil and natural gas to biomass on a large scale.
HMF, to be precise: hydroxymethylfurfural, is one of the hot candidates, as Esteban Meija says. However, new ideas are also needed for the simple and cheap implementation of this raw material and its products on a large scale.
Dr. Meija's research contacts with Vietnam led to cooperation with Nguyen Trung Thanh, a professor at Hanoi University of Technology. Meija's junior research group offered him the opportunity to develop a simplified process for the production of HMF from rice straw in his habilitation thesis. In parallel, Meija assigned a student from Venezuela, Abel Salazar, the task of improving the PEF process based on HMF.
Balloons in the Laboratory
In principle, in this process, a mixture of HMF and alcohol reacts with oxygen and in the presence of a catalyst to form an ester, or more precisely a diester, which can be polymerised to PEF in a further step (see scheme). Compared to the previous process, the new process at the LIKAT manages with a fractional amount of heat and pressure.
On top of that, the researchers do not supply the required oxygen to the reaction in concentrated form, but rather from the air - which simplified the process considerably and apparently also increased the fun factor of the experiments: "At first we simply took balloons, blew them up in the laboratory and put them over the apparatus. With three or four reactions at the same time, it made for a nice party scene in the lab.
But the use of room air had a disadvantage for the reaction: it ran too slowly. The product could only be examined the next morning. Meija and his team solved the problem in two places. First, they slightly increased the pressure and found an optimum at 20 bar. "Secondly, we replaced our reaction vessel with a microflow reactor."
The starting materials, essentially a mixture of HMF and alcohol, are pressed through a system of fine tubes with oxygen or air. Due to the capillary forced guidance, the oxygen molecules come into contact with the starting mix in a well-dosed manner. The reaction mixture then passes through a cartridge. There the catalyst is located, which starts the reaction, in this case particles of cobalt oxide and ruthenium, applied to the surface of small beads.
This arrangement enables the "oxidative esterification", as chemists call this reaction, and above all it allows a continuous process. The catalyst is not consumed, it can be used again and again. The product, the esterified PEF component, leaves the cartridge as a liquid and can now be polymerized.
"Our reaction now runs 15 times faster than when the experiments began," says Esteban Meija. The chemist is convinced that the result will interest many people. "That's why we have decided to publish the results in open access."
Dr. Esteban Mejia
Dr. Martha Höhne | idw - Informationsdienst Wissenschaft
Circular RNA makes fruit flies live longer
26.06.2020 | Max-Planck-Institut für Biologie des Alterns
How ApoE4 endangers the brain
26.06.2020 | Max Delbrück Center for Molecular Medicine in the Helmholtz Association
With an X-ray experiment at the European Synchrotron ESRF in Grenoble (France), Empa researchers were able to demonstrate how well their real-time acoustic monitoring of laser weld seams works. With almost 90 percent reliability, they detected the formation of unwanted pores that impair the quality of weld seams. Thanks to a special evaluation method based on artificial intelligence (AI), the detection process is completed in just 70 milliseconds.
Laser welding is a process suitable for joining metals and thermoplastics. It has become particularly well established in highly automated production, for...
A research team from the Max Planck Institute for the Structure of Dynamics (MPSD) and the University of Oxford has managed to drive a prototypical antiferromagnet into a new magnetic state using terahertz frequency light. Their groundbreaking method produced an effect orders of magnitude larger than previously achieved, and on ultrafast time scales. The team’s work has just been published in Nature Physics.
Magnetic materials have been a mainstay in computing technology due to their ability to permanently store information in their magnetic state. Current...
The Venus flytrap (Dionaea muscipula) takes only 100 milliseconds to trap its prey. Once their leaves, which have been transformed into snap traps, have...
NASA-NOAA's Suomi NPP satellite observed a huge Saharan dust plume streaming over the North Atlantic Ocean, beginning on June 13. Satellite data showed the dust had spread over 2,000 miles.
At NASA's Goddard Space Flight Center in Greenbelt, Maryland, Colin Seftor, an atmospheric scientist, created an animation of the dust and aerosols from the...
Molecular switches are the molecular counterparts of electrical switches and play an important role in many processes in nature. Nanotechnologist now produced a photographic film at the atomic level and thus tracked the motion of a molecular building block. The result was a light-controlled "pedalo-type motion", going forward and backward. The study has been published in the "The Journal of Physical Chemistry Letters".
Molecular switches – they are the molecular counterparts of electrical switches and play an important role in many processes in nature. Such molecules can...
19.05.2020 | Event News
07.04.2020 | Event News
06.04.2020 | Event News
26.06.2020 | Studies and Analyses
26.06.2020 | Physics and Astronomy
26.06.2020 | Life Sciences