CONTINOUS SEPARATION OF COMMODITY CHEMICALS FROM PARTIALLY DEOXYGENATED PYROLYSIS OILS VIA FLASH DISTILLATION

Open Access
Author:
Mcvey, Thomas Matthew
Graduate Program:
Agricultural and Biological Engineering
Degree:
Master of Science
Document Type:
Master Thesis
Date of Defense:
November 15, 2017
Committee Members:
  • Daniel Edward Ciolkosz, Thesis Advisor
  • Manish Kumar, Committee Member
  • Ali Demirci, Committee Member
Keywords:
  • pyrolysis
  • bio-oil
  • distillation
  • BTX
  • benzene
  • toluene
  • xylene
  • biomass
  • pyrolysis oil
  • separation
  • continuous distillation
Abstract:
This study investigated the potential for continuous flash distillation for fractionating partially deoxygenated bio-oils such as tail gas reactive pyrolysis (TGRP) bio-oil to extract the component chemicals of benzene, toluene, and xylene (BTX), which are critical feedstocks for producing many refinery products. A model chemical mixture was used to mimic the low-oxygen nature of TGRP bio-oil, as TGRP bio-oil was available in limited quantities. The process conditions investigated with respect to separation efficiency were temperature (120, 130, and 140°C) and input flow rate (2 and 3 mL min-1). Also investigated was steady-state operation, comparison of results between batch and continuous modes of distillation, and the use of a model bio-oil mixture as representative of low oxygen bio-oil, such as TGRP oil. Steady-state operation was found to be achieved in 9 of 13 runs according to a self-defined criterion. Mean BTX extraction percentage (gout/gin) for a flow rate of 2 mL min-1 was found to be 16.21% for 120°C, 34.31% for 130°C, and 50.81% for 140°C. while for 3 mL min-1 it was 15.14% for 120°C, 36.83% for 130°C, and 39.07% for 140°C. While the mass of BTX extracted per minute was found to be larger for modeled results compared to experimental results, the trends with respect to operating temperature were positively correlated, verifying the theoretical effects of operating conditions on BTX separation. Limited availability and crossover of relative data for comparable batch (amount of BTX distilled via tops = 7 wt%) and continuous (BTX = 1.83 wt% average per fraction) distillation runs allowed for only limited observations and comparisons between distillation modes. These results suggest that continuous, atmospheric distillation of low-oxygen bio-oils is a reasonable means for separating commodity, refinery-grade chemicals from biomass pyrolysis-derived bio-oils.