What is pyrolysis oil application

Refinement of pyrolysis oils

Development of a combined process for refining pyrolysis oil with biogenic alcohols and hydrogen

Researchers and engineers around the world are searching for optimal methods of producing chemical raw materials and fuels from biomass. Pyrolysis oils are an important intermediate stage. They have to be refined in order to produce fuel. In our project we are investigating whether esterification and acetal formation as well as the subsequent treatment with hydrogen can achieve this.

Background and purpose

The aim of the project is to produce a product with significantly improved properties from crude pyrolysis oil. It should be suitable both for motor use - and easier to process in refineries - and as a source of basic chemicals (aromatics, cycloalkanes). We want to reduce the acidity, water content and viscosity of pyrolysis oils and noticeably increase the calorific value and storage stability. During processing, the highest possible proportion of the energy primarily present in the biomass should be retained. In this way, we could make a significant contribution to saving 60% of the greenhouse gases in liquid fuels. There would be a long-term sales market for dry, biogenic residues from agriculture and forestry.


We test catalysts in batch and continuous trials. We use commercial catalysts, we get samples from industry. By varying the parameters time and pressure, their mechanical long-term stability and activity should be tested. We want to set up and operate a continuous, multi-stage hydrogenation plant, characterize products and draw up mass balances.

Our research questions

Can pyrolysis liquids for fuels be refined in such a way that they can be fed into a conventional refinery process?


The overall goal of the project was to improve the properties of pyrolysis crude oils for the production of basic chemicals or for use in engines. For this purpose, the effects of esterification or acetal formation and hydrogen treatment on the properties of the oils were investigated. Discontinuous screening tests with variation of the reaction conditions and the catalyst material formed the basis for the construction and operation of a continuous, multi-stage test facility. The results show that the proportions of water and acids in the pyrolysis oils from beech wood and barley straw can be effectively reduced by means of esterification and hydrogen treatment. If transition metal catalysts are used, the proportions of low molecular weight substances, especially benzenes and phenols, can be increased. This enabled intermediaries to be created from pyrolysis oil, which can be integrated into existing process routes in the chemical industry.

Links and Downloads

The final report can be found here shortly.

Thünen contact person

Participating Thünen partners


  • Agency for Renewable Resources e.V. (FNR)
    (national, public)