Secondary Reactions of Primary Tar from Biomass Pyrolysis: Characterization of Heavy Products by FT-ICR MS

Abstract

The aim of this study is to deeper understand the effect of homogeneous vapor-phase reactions on heavy components in condensed bio-oil. The fast pyrolysis of elm was conducted in a microfluidized-bed reactor (MFBR) at 500 °C. The primary tar formed in MFBR was immediately introduced into a secondary tubular reactor (STR), in which the secondary reactions occurred. The chemical components of both condensed primary tar and secondary products were characterized by atmospheric pressure photoionization Fourier transform ion cyclotron resonance mass spectrometry (APPI-FT-ICRMS). The results show that the condensed primary tar was mainly composed of dimers containing 3−4 oxygen atoms. Even at a low temperature of 500 °C, the secondary reactions would evidently promote the cracking of heavy C x H y O z compounds. More interestingly, large tetramers were generated probably by the recombination of smaller oligomers in secondary reactions. A long residence time (RT) would further facilitate the formation of oxygen-free compounds, especially for the large and condensed aromatic hydrocarbons. Van Krevelen diagrams confirm the processes (e.g., decarboxylation, decarboxylation, etc.) when the C x H y O z compounds were converted into unsaturated C x H y compounds .

Virtual Special Issue of Recent Advances in Analysis of Fuels and Products by Advanced Mass Spectrometry

“…Chiaberge et al provide a detailed characterization of the complex products in co-processing of biocrude and fossil crude oils with FT-ICR MS. Comprehensive composition analysis with high-resolution mass spectrometry has significant implications in evaluation of the processing route. Yang et al study homogeneous vapor-phase reactions on heavy components in a condensed bio-oil. Elm is pyrolyzed, and tar and secondary product are characterized by FT-ICR MS.…”

Van Krevelen diagrams based on machine learning visualize feedstock-product relationships in thermal conversion processes

“…Consequently, previous investigations using the van Krevelen diagram to understand the directions of several specific reactions can be challenging to apply to the analysis of mixtures. On the other hand, although there have been studies using the van Krevelen diagram to illustrate the thermal conversion reactions of real biomass and biodegradable wastes such as algae 29 , lignocellulosic biomass 30 , and digestate 31 , typically only single or a few cases are reported in each study. Therefore, there is interest in addressing these gaps and creating van Krevelen diagrams that better reflect the real-world applications of different thermal conversion techniques.…”