The aim of this study is to characterise and compare fast pyrolysis product yields from straw, high yielding perennial grasses and hardwoods. Feedstocks selected for this study include: wheat straw (Triticum aestivum), switch grass (Panicum virgatum), miscanthus (Miscanthus x giganteus), willow short rotation coppice (Salix viminalis) and beech wood (Fagus sylvatica). The experimental work is divided into two sections: analytical (TGA and Py-GC–MS) and laboratory scale processing using a continuously fed bubbling fluidized bed reactor with a capacity of up to 1kg/h. Pyrolysis-gas chromatography–mass spectrometry (Py-GC–MS) has been used to quantify pyrolysis products and simulate fast pyrolysis heating rates, in order to study potential key light and medium volatile decomposition products found in these feedstocks. Py-GC–MS quantification results show that the highest yields of furfural (0.57wt.%), 2-furanmethanol (0.18wt.%), levoglucosan (0.73wt.%), 1,2-benzenediol (0.27wt.%) and 2-methoxy-4-vinylphenol (0.38wt.%) were found in switch grass, and that willow SRC produced the highest yield of phenol (0.33wt.%). The bio-oil higher heating value was highest for switch grass (22.3MJ/kg). Water content within the bio-oil is highest in the straw and perennial grasses and lowest in the hardwood willow SRC. The high bio-oil and char heating value and low water content found in willow SRC, makes this crop an attractive energy feedstock for fast pyrolysis processing, if the associated production costs and harvest yields can be maintained at current reported values. The bio-oil from switch grass has the highest potential for the production of high value chemicals.

The research investigates the fuel property variations associated with the time of harvest and the duration of storage of Miscanthus x giganteus over a one year period. The crop has been harvested at three different times: early (September 2009), conventional (April 2010) and late (June 2010). Once harvested the crop was baled and stored. Biomass properties of samples taken from different storage zones were compared. The thermochemical properties have been investigated using a range of analytical equipment including thermogravimetric analysis (TGA) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). In addition, bio-oil has been produced from the early, conventional and late harvest using a laboratory scale (300 g h(-1)) fast pyrolysis unit. The potential organic liquid yield (on dry basis, also excluding the reaction water generated) based on the laboratory fast pyrolysis processing undertaken in this study, was found to vary between 2.82 and 3.18 dry t ha(-1) for the early and the late harvest respectively. The bio-oil organic yield was reduced by approximately 11% (0.36 t ha(-1)) between the early and the late harvest. Char yield was also reduced by approximately 18% (0.61 t ha(-1)). The highest gas yield (18.03%-1.60 t ha(-1)) was observed for the conventional harvest. Gas chromatography-mass spectrometry (GC-MS) analysis of the bio-oil shows that levoglucosan, methylbenzaldehyde and 1,2-benzenediol all increase as a consequence of delayed harvest. It was also observed that by delaying the harvest time the O:C atomic ratio is reduced and a more carbonaceous feedstock is produced. (C) 2013 Elsevier Ltd. All rights reserved.

The main aim of the work is to investigate sequential pyrolysis of willow SRC using two different heating rates (25 and 1500°C/min) between 320 and 520°C. Thermogravimetric analysis (TGA) and pyrolysis – gas chromatography – mass spectroscopy (Py–GC–MS) have been used for this analysis. In addition, laboratory scale processing has been undertaken to compare product distribution from fast and slow pyrolysis at 500°C. Fast pyrolysis was carried out using a 1kg/h continuous bubbling fluidized bed reactor, and slow pyrolysis using a 100g batch reactor. Findings from this study show that heating rate and pyrolysis temperatures have a significant influence on the chemical content of decomposition products. From the analytical sequential pyrolysis, an inverse relationship was seen between the total yield of furfural (at high heating rates) and 2-furanmethanol (at low heating rates). The total yield of 1,2-dihydroxybenzene (catechol) was found to be significant higher at low heating rates. The intermediates of catechol, 2-methoxy-4-(2-propenyl)phenol (eugenol); 2-methoxyphenol (guaiacol); 4-Hydroxy-3,5-dimethoxybenzaldehyde (syringaldehyde) and 4-hydroxy-3-methoxybenzaldehyde (vanillin), were found to be highest at high heating rates. It was also found that laboratory scale processing alters the pyrolysis bio-oil chemical composition, and the proportions of pyrolysis product yields. The GC–MS/FID analysis of fast and slow pyrolysis bio-oils reveals significant differences.

The research is concerned with thermochemical characterisation of straws and high yielding perennial grasses. Crops selected for this study include wheat straw (Triticum aestivum), rape straw (Brassica napus), reed canary grass (Phalaris arundinacea) and switch grass (Panicum virgatum). Thermogravimetric analysis (TGA) was used to examine the distribution of char and volatiles during pyrolysis up to 900 °C. Utilising multi-heating rate thermogravimetric data, the Friedman iso-conversional kinetic method was used to determine pyrolysis kinetic parameters. Light and medium volatile decomposition products were investigated using pyrolysis–gas chromatography–mass spectrometry (Py–GC–MS) up to 520 °C. The 22 highest yielding identifiable cellulose, hemicellulose and lignin biomass markers were semi-quantified taking into consideration peak areas from GC chromatograms. Notable differences can be seen in butanedioic acid, dimethyl ester (hemicelluloses decomposition products), 2-methoxy-4-vinylphenol (lignin marker) and levoglucosan (intermediate pyrolytic decomposition product of cellulose) content when comparing perennial grasses with straw. From results presented in this study, perennial grasses such as switch grass, have the most attractive properties for fast pyrolysis processing. This is because of the observed high volatile yield content of 82.23%, heating value of 19.64 MJ/kg and the relatively low inorganic content.