Metathesis

Catalysis is indispensable in the chemical industry both for economic and environmental reasons. It is estimated that 90 % of commercially produced chemicals are synthesized via catalytic processes. The aspects of sustainability and green chemistry, e. g. the use of highly active catalyst systems at low catalyst loadings under mild reaction conditions in environmental benign media, became also essential.

Olefin metathesis is one of the fundamental catalytic reactions that initiated new industrial technology avenues in the 21st century. Its application in the field of green chemistry, especially in green catalysis is emerging. Olefin metathesis catalysts can initiate the breaking and creation of new carbon-carbon bond – which is one of the strongest chemical bonds in nature. These unique – in general, high energy demanding chemical – process can be initiated by olefin metathesis catalysts under ambient conditions at low (even at as low as several ppm) catalyst loading levels, resulting in high atom economic (waste free) chemical transformations with a low carbon footprint.

One of the most important missions of the Green Chemistry Research Group is to develop new, cutting-edge green catalyst systems for sustainable, low-energy chemical processes.

In 2022 the global plastics production reached an annual value of 400 Mt and this is expected to rise to 1000 Mt by 2050. Fugitive persistent plastics are a major problem on land and especially in the Earth’s oceans where the mass of plastics is projected to exceed the total mass of fish by the year 2050. They are causing serious environmental issues and rising concerns about microplastic pollution and its impact on ecosystems and health.

Currently, only limited recycling strategies exist to convert end-of-life plastics. It is estimated that only 10% of the plastic waste ever generated was recycled, and only 14% of that was recycled multiple times (2017). While the share of mechanically recycled - in general downgraded - plastics is increasing year by year (8.3% of annual production in 2022), chemical recycling technologies - producing virgin grade polymers - currently account for less than 0.1% of annual plastic production.

Polyolefins - such as polyethylene and polypropylene packaging materials - dominated the production of plastics with a combined share of 45% in 2022 and currently lack efficient end-of-life treatment.

In our laboratories novel, sustainable chemical processes are developed for catalytic conversion of persistent plastics to high value, sustainable chemicals, materials including propylene and biodegradble polymers.

Nowadays one of the biggest challenges for the energy industry is the transition from fossil-fuel power sources to renewable ones. Therefore, the need for the higher exploitation of renewable energy is now clear in all segments of the energy industry. Storing renewable energy in low cost, environmentally benign materials is among the most intensively investigated research areas. Among these materials, ammonia borane (AB) received extensive attention in recent years as an emerging hydrogen storage material due to its high hydrogen density (19.6 wt %), nontoxicity, stability, and water solubility. Although AB itself is stable in water, its catalytic dehydrogenation (2 mol eq) in aqueous media produces borazine whose tandem hydrolytic reaction enables further hydrogen release (1 mol eq). Thus, water serves both as a reaction medium and also a pure hydrogen fuel source (33% of overall released H2).

Our ongoing research is focusing on the development of novel, water soluble or solid supported AB hydrolytic dehydrogenation catalysts for the efficient renewable energy storage.

The research aims to develop green catalytic systems and chemical processes for transforming plastic waste and renewable resources, such as vegetable oils, into sustainable polymers that are chemically recyclable and biodegradable. The objective is to design innovative catalyst systems and processes that enable:

- The selective breakdown of long-chain olefins into propylene derived from either persistent plastic (e.g. polyethylene) waste or renewable sources.

- The conversion of propylene into biodegradable plastics, including polybutylene adipate terephthalate (PBAT) and polybutylene succinate (PBS).