A process for the prepn. of arom. compds. from a feed stream contg. biomass or mixts. of biomass, the process comprising: a) subjecting a feed stream contg. biomass or mixts. of biomass to a process to afford a conversion product comprising arom. compds.; b) recovering the arom. compds. from said conversion product; c) sepg. a higher mol. wt. fraction comprising polyarom. hydrocarbons (PAH) from a lower mol. wt. fraction comprising benzene, toluene and xylene (BTX) by distn.; d) reducing at least part of said higher mol. wt. fraction to obtain a reduced fraction comprising polycyclic aliphatics (PCA); and e) subjecting the higher mol. wt. fraction obtained in step c), the reduced fraction obtained in step d), or a mixt. thereof, to a process to obtain lower mol. wt. aroms. (BTX). [on SciFinder(R)]
Bio-aromatics (benzene, toluene, xylenes, BTX) were prepared by the catalytic pyrolysis of six different black liquors using both in situ and ex situ approaches. A wide range of catalysts was screened and conditions were optimized in microscale reactors. Up to 7 wt % of BTX, based on the organic fraction of the black liquors, was obtained for both the in situ and ex situ pyrolysis ( T = 500-600 °C) using a Ga-modified H-ZSM-5 catalyst. The in situ catalytic pyrolysis of black liquors from hardwood paper mills afforded slightly higher yields of aromatics/BTX than softwood black liquors, a trend that could be confirmed by the results obtained in the ex situ catalytic pyrolysis. An almost full deoxygenation of the lignin and carbohydrate fraction was achieved and both organic fractions were converted to a broad range of (substituted) aromatics. The zeolite catalyst used was remarkably stable and even after 100 experiments in batch mode with intermittent oxidative catalyst regeneration, the yields and selectivity toward BTX remained similar. The ex situ pyrolysis of black liquor has potential for large-scale implementation in a paper mill without disturbing the paper production process.
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