Pyrolysis is one of the thermochemical technologies for converting biomass into energy and chemical products consisting of liquid bio-oil, solid biochar, and pyrolytic gas. Depending on the heating rate and residence time, biomass pyrolysis can be divided into three main categories slow (conventional), fast and flash pyrolysis mainly aiming at maximising either the bio-oil or biochar yields. Synthesis gas or hydrogen-rich gas can also be the target of biomass pyrolysis. Maximised gas rates can be achieved through the catalytic pyrolysis process, which is now increasingly being developed. Biomass pyrolysis generally follows a three-step mechanism comprising of dehydration, primary and secondary reactions. Dehydrogenation, depolymerisation, and fragmentation are the main competitive reactions during the primary decomposition of biomass. A number of parameters affect the biomass pyrolysis process, yields and properties of products. These include the biomass type, biomass pretreatment (physical, chemical, and biological), reaction atmosphere, temperature, heating rate and vapour residence time. This manuscript gives a general summary of the properties of the pyrolytic products and their analysis methods. Also provided are a review of the parameters that affect biomass pyrolysis and a summary of the state of industrial pyrolysis technologies.

Lignocellulosic biomass pyrolysis: A review of product properties and effects of pyrolysis parameters

Fossil fuel consumption in transportation system and energy-intensive sectors as the principal pillar of civilization is associated with progressive release of greenhouse gases. Hydrogen as a promising energy carrier is a perfect candidate to supply the energy demand of the world and concomitantly reduce toxic emissions. This article gives an overview of the state-of-the-art hydrogen production technologies using renewable and sustainable energy resources. Hydrogen from supercritical water gasification (SCWG) of biomass is the most cost effective thermochemical process. Highly moisturized biomass is utilized directly in SCWG without any high cost drying process. In SCWG, hydrogen is produced at high pressure and small amount of energy is required to pressurize hydrogen in the storage tank. Tar and char formation decreases drastically in biomass SCWG. The low efficiency of solar to hydrogen system as well as expensive photovoltaic cell are the most important barriers for the widespread commercial development of solar-based hydrogen production. Since electricity costs play a crucial role on the final hydrogen price, to generate carbon free hydrogen from solar and wind energy at a competitive price with fossil fuels, the electrical energy cost should be four times less than commercial electricity prices.

Hydrogen production from renewable and sustainable energy resources: Promising green energy carrier for clean development

http://www.adktroutguide.com/files/2003_Pyrolysis_of_biomass_and_sludge_to_produce_fuels_and_chemical_feedstocks.pdf

Pyrolysis of biomass to produce fuels and chemical feedstocks

An overview of hydrogen production from biomass

Slow-pyrolysis of biomass for the production of biochar, a stable carbon-rich solid by-product, has gained considerable interest due to its proven role and application in the multidisciplinary areas of science and engineering. An alternative to slow-pyrolysis is a relatively new process called hydrothermal carbonization (HTC) of biomass, where the biomass is treated with hot compressed water instead of drying, has shown promising results. The HTC process offers several advantages over conventional dry-thermal pre-treatments like slow-pyrolysis in terms of improvements in the process performances and economic efficiency, especially its ability to process wet feedstock without pre-drying requirement. Char produced from both the processes exhibits significantly different physiochemical properties that affect their potential applications, which includes but is not limited to carbon sequestration, soil amelioration, bioenergy production, and wastewater pollution remediation. This paper provides an updated review on the fundamentals and reaction mechanisms of the slow-pyrolysis and HTC processes, identifies research gaps, and summarizes the physicochemical characteristics of chars for different applications in the industry. The literature reviewed in this study suggests that hydrochar (HTC char) is a valuable resource and is superior to biochar in certain ways. For example, it contains a reduced alkali and alkaline earth and heavy metal content, and an increased higher heating value compared to the biochar produced at the same operating process temperature. However, its effective utilization would require further experimental research and investigations in terms of feeding of biomass against pressure; effects and relationships among feedstocks compositions, hydrochar characteristics and process conditions; advancement in the production technique(s) for improvement in the physicochemical behavior of hydrochar; and development of a diverse range of processing options to produce hydrochar with characteristics required for various industry applications.

A comparative review of biochar and hydrochar in terms of production, physico-chemical properties and applications

Slow, fast and flash pyrolysis of rapeseed

Fixed-bed slow and fast pyrolysis experiments have been conducted on a sample of rapeseed. The experiments were performed in two different pyrolysis reactors, namely a fixed-bed Heinze and a well-swept fixed-bed tubular retort to investigate the effects of heating rate, pyrolysis temperature, particle size, sweep gas velocity on the pyrolysis product yields and chemical compositions. The maximum oil yield of 51.7% was obtained in the Heinze reactor 550°C, with a particle size range of +0.6– 1.8 mm (sweep gas 100 cm 3 min −1 N 2 ) at a heating rate of 30° C min −1 . In the well-swept fixed-bed reactor, the maximum oil yield of 68% was obtained at a heating rate of 300° C min −1 . Chromatographic and spectroscopic studies on the pyrolytic oil showed that the oil obtained from rapeseed could be use as a renewable fuels and chemical feedstock.

Fixed-bed pyrolysis of rapeseed (Brassica napus L.).

Pyrolysis of rapeseed in a free fall reactor for production of bio-oil

Oil production from an arid-land plant: fixed-bed pyrolysis and hydropyrolysis of Euphorbia rigida

Pyrolytic behaviors of biomass/coal mixtures were investigated under a heating rate of 7 °C min-1, over a range of pyrolysis temperatures between 400 and 700 °C, and the blending ratio of coal in mixtures was varied between 0 and 100 wt %. The results indicated that considerable synergistic effects were observed during the copyrolysis in a fixed-bed reactor leading to an increase in the oil yield at lower than coal blending ratios of 33%. At the lower blending coal ratio conditions, the oil yields are higher than the expected ones, calculated as the sum of oil fractions produced by pyrolysis of each separated component. The maximum pyrolysis oil yield of 39.5% was obtained with 5% of lignite mixed with safflower seed. The obtained oils are characterized by Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance, gas chromatography mass spectrometry, and elemental analysis. These findings can potentially help to understand and predict the behavior of coal/biomass blends in practical liquefac...

Copyrolysis of Seyitömer−Lignite and Safflower Seed: Influence of the Blending Ratio and Pyrolysis Temperature on Product Yields and Oil Characterization

O. Mete Kockar

Papers

Slow, fast and flash pyrolysis of rapeseed

Fixed-bed pyrolysis of rapeseed (Brassica napus L.).

Pyrolysis of rapeseed in a free fall reactor for production of bio-oil

Oil production from an arid-land plant: fixed-bed pyrolysis and hydropyrolysis of Euphorbia rigida

Copyrolysis of Seyitömer−Lignite and Safflower Seed: Influence of the Blending Ratio and Pyrolysis Temperature on Product Yields and Oil Characterization