Norms and standards for fast pyrolysis liquids: 1. Round robin test

The International Energy Agency-European Union (IEA-EU) round robin test in 2000 was carried out by learning from earlier round robin tests and by employing improved analytical methods. In general, the accuracy of all physical analyses was good for homogenous pyrolysis liquids. For heterogeneous liquids, erroneous results were obtained, especially for kinematic viscosity and stability index. Good laboratory practice, such as proper calibration of equipment, and good background knowledge of the analysis sample, prevents systematic errors.

The main conclusions were: Karl–Fischer titration is recommended for analysing water in pyrolysis liquids. the solids content determined as ethanol insolubles is accurate for white wood (stem wood, no bark or needles) liquids, while a more powerful solvent, like a mixture of methanol and dichloromethane (1:1 vol.%), is required for extractive-rich liquids from feedstocks such as forest residues. for elemental analysis at least triplicates are recommended due to the small sample size. Special attention should be paid to nitrogen standards. They should have a similar range of nitrogen as the sample. Kinematic viscosity is an accurate method at 40 °C for pyrolysis liquids. Rotating viscotesters with a cover at low temperatures (≤50 °C) can also be used. Stability index needs more specific instructions. Results of chemical characterisation were not very consistent. Proper standard solutions have to be used with known amounts of compounds for quantitative analyses.