Lignocellulosic biomass is an inexpensive and abundant plant material that can be utilized for the production of chemicals and fuels. Thermochemical processes such as pyrolysis and gasification provide economically viable routes for the conversion of lignocellulosic biomass into these globally important commodities. Due to the high heating rates used in pyrolysis and gasification, tar compounds and their subsequent secondary vapor-phase cracking are of significance. Though tar compounds produced from pyrolysis can be catalytically upgraded to chemicals and fuels, they can be detrimental in gasification, wherein tar compounds cause coking, fouling, and catalyst deactivation. In order to design optimal thermochemical processes for the conversion of lignocellulosic biomass into chemicals and fuels, it is crucial to understand the secondary vapor-phase cracking process of tar compounds.<br/><br/>Despite many studies examining the homogeneous secondary cracking of biomass tar existing in the literature, the thermal decomposition processes are not completely understood. Much of this lack of understanding is due to the complex, heterogeneous nature of biomass tar. A useful approach is to examine the pyrolysis of model compounds that are actual components or are representative of compounds found in biomass tar. In this study, we focus on the model tar compounds guaiacol and two of its alkyl-substituted derivatives: 4-methylguaiacol and 4-ethylguaiacol. Pyrolysis experiments were conducted at temperatures between 300 and 900<sup>o</sup>C and one second residence time using a nonisothermal laminar-flow quartz reactor operated at atmospheric pressure. Light gas products produced from guaiacol, 4-methylguaiacol and 4-ethylguaiacol were identified and quantified using GC-FID/TCD. We discuss differences in light gas production and based on the overall results from these model compounds, we describe a mechanism that is relevant for the thermal decomposition of the guaiacyl-tar components in lignin during pyrolysis and gasification.

Differences in light gas production from the gas-phase pyrolysis of guaiacol, 4-methylguaiacol, and 4-ethylguaiacol

251st National Meeting (2016)

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