Valorization of arid land biomass: a case for pyrolysis

  • Prosper Dzidzienyo

Student thesis: Master's Thesis

Abstract

This study focused on producing precursors for jet-fuels using biomass common in arid regions such as waste plant biomass and biomass that can be grown with sea water in desert areas, from slow pyrolysis, and studying the decomposition rates and Arrhenius kinetic parameters that describe the pyrolysis reaction with Thermo-gravimetric Analysis. Different biomass types sampled include Salicornia bigelovii, date palms (Phoenix dactylifera) agricultural residues, macroalgae Ulva lactuca and microalgae Arthrospira platensis. Also, two residues streams: food waste and secondary waste sludge (from wastewater treatment plants). Slow Pyrolysis was performed on all biomass types and the distribution of pyro-oil, char and gases from these biomasses are presented. Pyro-oil yields varied from 0.4% to 37% for different biomasses from 300 °C to 550 °C. Salicornia bigelovii straw gave the highest yield of pyro-oil at 34% at 450°C while lows of 12% was obtained with Ulva lactuca. This low yield was attributed to the high ash content due to the presence of non-combustible salts and crystal formation at high temperatures. Scanning electron micrographs of the chars of U. lactuca revealed the presence of these salts. The mass loss data obtained from Thermogravimetric Analysis of S. bigelovii and date palm revealed the decomposition rate peaked between 315°C and 338°C for both biomasses at all heating rates, 5K/min, 10K/min and 15K/min during the active pyrolysis phase. The activation energy for S. bigelovii and date palm straw during this active pyrolysis phase was estimated as 147.6 KJ/mol and 164.7 KJ/mol respectively with pre-exponential factors of 3.13 × 109 /min and 9.55 ×1010/min for the respective biomasses. Other isoconversional models were used to determine these kinetic parameters during other phases of the pyrolysis reaction.
Date of AwardMay 2017
Original languageAmerican English
SupervisorJens Schmidt (Supervisor)

Keywords

  • Biomass Fuel Production
  • Jet Fuel Precursors
  • Slow Pyrolysis
  • Date Palms
  • Waste Plant Biomass.

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