Bio-oil from Wheat Straw and Hydrogen from Aqueous Phase of Bio-oil
Date
2013-07-10
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Abstract
Hydrogen is currently produced mostly from hydrocarbons, such as naphtha and natural gas; and, the demand for hydrogen in industrial applications, like oil refining, bitumen upgrading or in fuel cells, is increasing natural gas consumption and, consequently, applying pressure on the supply of natural gas. As such, the supply of natural energy resources is becoming a challenging prospect in the 21st century.
Renewable energy sources, such as biomass, are therefore presently gaining increased attention. Accordingly, a viable route towards hydrogen production from biomass, such as agricultural residues, has been developed through the process of catalytic steam reforming of the aqueous fraction of biomass pyrolysis oil. This method consists of two stages: generation of bio-oil from biomass via a fast pyrolysis reaction in a fluidized bed reactor in the first stage, followed by application of the catalytic steam-reforming process on the aqueous phase of bio-oil to produce renewable hydrogen in a fixed bed steam reformer unit in the second stage. The overarching aim of this study was evaluation of both stages of this method, thereby improving the efficiency of hydrogen production from biomass.
In the first stage, wheat straw as biomass was converted into pyrolytic oil, char and gases under high-temperature conditions in a fluidized bed reactor. The main operating parameters of the pyrolysis process were evaluated for producing high quality bio-oil with maximum yield. Under the optimal conditions of pyrolysis (reaction temperature of about 500°C and wheat straw particle size of less than 0.6 mm), the maximum yield of bio-oil exceeded 50% by weight. In order to evaluate the quality of bio-oil produced through this process, several characterization methods, such as elemental analysis and Karl Fischer titration, were applied.
In the second stage (catalytic steam-reforming process), aqueous phases of a commercial bio-oil, as well as the bio-oil produced in the first stage, were converted to hydrogen in a catalytic fixed bed steam reformer. With the commercial bio-oil, the effects of three groups of nickel-alumina based catalysts developed in-house were evaluated in terms of their yield for hydrogen production. Additionally, the operational conditions of the catalytic steam-reforming process were evaluated for a higher hydrogen yield. The highest hydrogen yield of about 65% was achieved by using the most effective catalyst (Ru-Ni/Al2O3 with 14 wt% Ni) in the case of the aqueous commercial bio-oil under the following optimal conditions: temperature of 850°C and a space velocity (WHSv) of 10 h-1. With the aqueous laboratory-made bio-oil, hydrogen was produced with a yield of about 60% over the same catalyst and under similar operational conditions.
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Engineering--Chemical
Citation
Pouralamdari Meibod, M. (2013). Bio-oil from Wheat Straw and Hydrogen from Aqueous Phase of Bio-oil (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/25133