(570h) Performance of Microwave-Assisted Catalysis for Production of Upgraded Pyrolysis Bio-Oil from Poplar Species in a Continuous-Flow System

The aim of this study is to investigate the performance of a microwave-assisted catalytic process for upgrading pyrolysis oil. The bio-oil was obtained from ground poplar biomass in a continuous-flow rotative heating reactor, via pyrolysis at 500°C with a mean residence time of 15 minutes, as indicated by preliminary studies for maximum liquid production, under a 95%N₂/5%H₂ atmosphere. The exiting volatile stream was split three-way: one stream was immediately condensed in a cold-trap at substantive negative temperatures, the second stream was passed through a conventionally heated catalytic bed prior to flash-cooling and condensing, and the third stream was passed through a catalytic bed heated using microwaves. Different zeolite-based catalysts (HZSM5, Ni-ZSM5, Fe-ZSM5) were investigated to evaluate their performance under longer processing times. The catalytic bed temperatures ranged from (200 to 375°C), controlled via microwave power level and temperature controller, respectively. Upgraded bio-oil samples were collected at different time intervals (every 15 minutes) in order to evaluate the time-series performance of each catalyst for durations up to 3 hours. Bio-oil quantitative analysis was undertaken via a mass balance on the liquid, gas, and char, while bio-oil qualitative analysis was performed using GC-MS, CHNO, and bomb calorimetry. The results were compared with those obtained with conventional heating, and with the initial pyrolysis oil. Different catalyst – to – initial carbon ratios were investigated, and the catalysts were characterised with respect to surface properties, and surface activity, and extent of coking. Results indicate that microwave heating of the catalyst bed results in a better long-term performance of the catalyst with respect to its catalytic activity, with variations among the different catalysts used.