Catalytic fast pyrolysis of duckweed: Effects of pyrolysis parameters and optimization of aromatic production

• Catalytic fast pyrolysis of duckweed was carried out on micro-furnace pyrolyzer.
• Effects of pyrolysis temperature and catalyst-to-biomass ratio were investigated.
• Response surface models based on full factorial design were established.
• The optimal operating conditions for specific aromatic compounds were obtained.

Catalytic fast pyrolysis (CFP) of duckweed is a potential source for biorenewable gasoline and diesel fuel production, but its ability to produce aromatics has not been investigated in detail. In this study, we employed a micro-pyrolyzer coupled with gas chromatograph–mass spectrometer, flame ionization detector, and a thermal conductivity detector to conduct CFP of duckweed (Lemna minor) with HZSM-5 catalyst and obtained promising yields of total aromatic hydrocarbon (TAH) and benzene, toluene, and xylene (BTX). In the operating conditions studied, pyrolysis temperatures and catalyst-to-biomass ratios (CBR) had significant effects on product yields and distributions. Duckweed CFP can be optimized to maximize either the TAH yield or the output of the BTX components. Optimal operating conditions were determined based on response surface methodology (RSM) with a 4 × 5 full factorial design (FFD). The RSM predicted optimal TAH and xylene carbon yields to be 27.2 mol% and 6.2 mol% at 736 °C and 662 °C, respectively, with CBR of 16:1. Optimal benzene and toluene carbon yields of 5.5 mol% and 8.0 mol%, respectively, were obtained at 750 °C and CBR of 20:1.