Distributed production of hydrogen by auto-thermal reforming of fast pyrolysis bio-oil

We demonstrated an auto-thermal reforming process for producing hydrogen from biomass pyrolysis liquids. Using a noble metal catalyst (0.5% Pt/Al₂O₃ from BASF) at a methane-equivalent space velocity of around 2000 h⁻¹, a reformer temperature of 800 °C–850 °C, a steam-to-carbon ratio of 2.8–4.0, and an oxygen-to-carbon ratio of 0.9–1.1, we produced 9–11 g of hydrogen per 100 g of fast pyrolysis bio-oil, which corresponds to 70%–83% of the stoichiometric potential. The elemental composition of bio-oil and the bio-oil carbon-to-gas conversion, which ranged from 70% to 89%, had the most significant impact on the yield of hydrogen. Because of incomplete volatility the remaining 11%–30% of bio-oil carbon formed deposits in the evaporator. Assuming the same process efficiency as that in the laboratory unit, the cost of hydrogen production in a 1500 kg/day plant was estimated at $4.26/kg with the feedstock, fast pyrolysis bio-oil, contributing 56.3% of the production cost.     

Catalytic pyrolysis of microalgae to high-quality liquid bio-fuels

The pyrolytic conversion of chlorella algae to liquid fuel precursor in presence of a catalyst (Na₂CO₃) has been studied. Thermal decomposition studies of the algae samples were performed using TGA coupled with MS. Liquid oil samples were collected from pyrolysis experiments in a fixed-bed reactor and characterized for water content and heating value. The oil composition was analyzed by GC-MS. Pretreatment of chlorella with Na₂CO₃ influences the primary conversion of chlorella by shifting the decomposition temperature to a lower value. In the presence of Na₂CO₃, gas yield increased and liquid yield decreased when compared with non-catalytic pyrolysis at the same temperatures. However, pyrolysis oil from catalytic runs carries higher heating value and lower acidity. Lower content of acids in the bio-oil, higher aromatics, combined with higher heating value show promise for production of high-quality bio-oil from algae via catalytic pyrolysis, resulting in energy recovery in bio-oil of 40%.     

Production of a hydrogen-rich gas from fast pyrolysis bio-oils: Comparison between homogeneous and catalytic steam reforming routes

The aim of the present work is to produce hydrogen from biomass through bio-oil. Two possible upgrading routes are compared: catalytic and non-catalytic steam reforming of bio-oils. The main originality of the paper is to cover all the steps involved in both routes: the fast pyrolysis step to produce the bio-oils, the water extraction for obtaining the bio-oil aqueous fractions and the final steam reforming of the liquids. Two reactors were used in the first pyrolysis step to produce bio-oils from the same wood feedstock: a fluidized bed and a spouted bed. The mass balances and the compositions of both batches of bio-oils and aqueous fractions were in good agreement between both processes. Carboxylic acids, alcohols, aldehydes, ketones, furans, sugars and aromatics were the main compounds detected and quantified. In the steam reforming experiments, catalytic and non-catalytic processes were tested and compared to produce a hydrogen-rich gas from the bio-oils and the aqueous fractions. Moreover, two different catalytic reactors were tested in the catalytic process (a fixed and a fluidized bed). Under the experimental conditions tested, the H₂ yields were as follows: catalytic steam reforming of the aqueous fractions in fixed bed (0.17 g H₂/g organics) > non-catalytic steam reforming of the bio-oils (0.14 g H₂/g organics) > non-catalytic steam reforming of the aqueous fractions (0.13 g H₂/g organics) > catalytic steam reforming of the aqueous fractions in fluidized bed (0.07 g H₂/g organics). These different H₂ yields are a consequence of the different temperatures used in the reforming processes (650 °C and 1400 °C for the catalytic and the non-catalytic, respectively) as well as the high spatial velocity employed in the catalytic tests, which was not sufficiently low to reach equilibrium in the fluidized bed reactor.     

Techno-economic comparisons of hydrogen and synthetic fuel production using forest residue feedstock

Mobile distributed pyrolysis facilities have been proposed for delivery of a forest residue resource to bio-fuel facilities. This study examines the costs of producing hydrogen or synthetic petrol (gasoline) and diesel from feedstock produced by mobile facilities (bio-oil, bio-slurry, torrefied wood). Results show that using these feedstock can provide fuels at costs competitive to conventional bio-fuel production methods using gasification of a woodchip feedstock. Using a bio-oil feedstock in combination with bio-oil steam reforming or bio-oil upgrading can produce hydrogen or petrol and diesel at costs of 3.25 $ kg⁻¹ or 0.86 $ litre⁻¹, respectively, for optimally sized bio-fuel facilities. When compared on an energy basis ($ GJ⁻¹), hydrogen production costs tend to be lower than those for synthetic petrol or diesel production across a variety of bio-fuel production pathways.     

Optimum conditions for maximising pyrolysis liquids of oil palm empty fruit bunches

As production of palm oil is expanding, a more efficient use of oil palm biomass to obtain more energy from oil palm plantations is investigated. The work was carried out on a fluidised bed bench scale fast pyrolysis unit, with the objective of determining the important conditions and key variables which are required to maximise the liquid yield and its quality. The investigation on the impact of reactor temperature, varying residence time by changing the nitrogen flow rate and combined impact of ash content and particle size on the product yields is presented. The properties of the liquid product were analysed and compared with wood derived bio-oil and petroleum fuels. It was found that in all cases the liquid product separated into two phases presenting difficulties for fuel applications, which are critically discussed. Potential solutions are also proposed which include upgrading of the liquid for fuel applications and other useful applications.     

Selective catalytic fast pyrolysis of Jatropha curcas residue with metal oxide impregnated activated carbon for upgrading bio-oil

Jatropha curcas waste was subjected to catalytic pyrolysis at 873 K using an analytical pyrolysis–gas chromatography/mass spectrometry in order to investigate the relative effect of various metal oxide/activated carbon (M/AC) catalysts on upgrading bio-oil from fast pyrolysis vapors of Jatropha waste residue. A commercial AC support was impregnated with Ce, Pd, Ru or Ni salts and calcined at 523 K to yield the 5 wt.% M/AC catalysts, which were then evaluated for their catalytic deoxygenation ability and selectivity towards desirable compounds. Without a catalyst, the main vapor products were fatty acids of 60.74% (area of GC/MS chromatogram), while aromatic and aliphatic hydrocarbon compounds were presented at only 11.32%. Catalytic pyrolysis with the AC and the M/AC catalysts reduced the oxygen-containing (including carboxylic acids) products in the pyrolytic vapors from 73.68% (no catalyst) to 1.60–36.25%, with Ce/AC being the most effective catalyst. Increasing the Jatropha waste residue to catalyst (J/C) ratio to 1:10 increased the aromatic and aliphatic hydrocarbon yields in the order of Ce/AC > AC > Pd/AC > Ni/AC, with the highest total hydrocarbon proportion obtained being 86.57%. Thus, these catalysts were effective for deoxygenation of the pyrolysis vapors to form hydrocarbons, with Ce/AC, which promotes aromatics, Pd/AC and Ni/AC as promising catalysts. In addition, only a low yield (0.62–7.80%) of toxic polycyclic aromatic hydrocarbons was obtained in the catalytic fast pyrolysis (highest with AC), which is one advantage of applying these catalysts to the pyrolysis process. The overall performance of these catalysts was acceptable and they can be considered for upgrading bio-oil.     

Characterization of bio-oil obtained from fruit pulp pyrolysis

Apricot pulps was pyrolyzed in a fixed-bed reactor under different pyrolysis conditions to determine the role of final temperature, sweeping gas flow rate and steam velocity on the product yields and liquid product composition with a heating rate of 5 °C/min. Final temperature range studied was between 300 and 700 °C and the highest liquid product yield was obtained at 550 °C. Liquid product yield increased significantly under nitrogen and steam atmospheres. For the optimum conditions, pyrolysis of peach pulp was furthermore studied. Liquid products obtained under the most suitable conditions were characterized by FTIR and ¹H-NMR. In addition, gas chromatography/mass spectrophotometer was achieved on all pyrolysis oils. Characterization showed that bio-oil could be a potential source for synthetic fuels and chemical feedstock.     

Biofuels from algae for sustainable development

Microalgae are photosynthetic microorganisms that can produce lipids, proteins and carbohydrates in large amounts over short periods of time. These products can be processed into both biofuels and useful chemicals. Two algae samples (Cladophora fracta and Chlorella protothecoid) were studied for biofuel production. Microalgae appear to be the only source of renewable biodiesel that is capable of meeting the global demand for transport fuels. Microalgae can be converted to biodiesel, bioethanol, bio-oil, biohydrogen and biomethane via thermochemical and biochemical methods. Industrial reactors for algal culture are open ponds, photobioreactors and closed systems. Algae can be grown almost anywhere, even on sewage or salt water, and does not require fertile land or food crops, and processing requires less energy than the algae provides. Microalgae have much faster growth-rates than terrestrial crops. the per unit area yield of oil from algae is estimated to be from 20,000 to 80,000 liters per acre, per year; this is 7–31 times greater than the next best crop, palm oil. Algal oil can be used to make biodiesel for cars, trucks, and airplanes. The lipid and fatty acid contents of microalgae vary in accordance with culture conditions. The effect of temperature on the yield of hydrogen from two algae (C. fracta and C. protothecoid) by pyrolysis and steam gasification were investigated in this study. In each run, the main components of the gas phase were CO₂, CO, H₂, and CH₄.The yields of hydrogen by pyrolysis and steam gasification processes of the samples increased with temperature. The yields of gaseous products from the samples of C. fracta and C. protothecoides increased from 8.2% to 39.2% and 9.5% to 40.6% by volume, respectively, while the final pyrolysis temperature was increased from 575 to 925 K. The percent of hydrogen in gaseous products from the samples of C. fracta and C. protothecoides increased from 25.8% to 44.4% and 27.6% to 48.7% by volume, respectively, while the final pyrolysis temperature was increased from 650 to 925 K. The percent of hydrogen in gaseous products from the samples of C. fracta and C. protothecoides increased from 26.3% to 54.7% and 28.1% to 57.6% by volume, respectively, while the final gasification temperature was increased from 825 to 1225 K. In general, algae gaseous products are higher quality than gaseous products from mosses.     

Fractional characterization of a bio-oil derived from rice husk

Bio-oils usually contain many types of compounds with various chemical properties. A bio-oil sample derived from rice husk through rapid pyrolysis was fractioned using solvent- or solid-extraction techniques based on their various properties. Ultraviolet-visible spectroscopy, three-dimensional excitation-emission matrix (EEM) fluorescence spectroscopy and Fourier transform infrared spectroscopy were used to characterize their various spectral properties for further understanding the characteristics of the bio-oil. Bio-oil mostly contains many aromatic ring components, acidic polar fractions, few weak- and non-polar components. The results all show that the main compounds and functional groups in the various bio-oil fractions were different and depended on the fractionation methods. The compositions of the bio-oil fractions were also analyzed with a gas chromatography/mass spectrometry (GC/MS) method. The consistency of the results obtained from the spectrometric methods with the GC/MS method indicates that the spectrometric methods have a good potential for rapid and effective characterization of bio-oils.