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The upgrading of pyrolysis oil to bio-fuel was investigated using sub- and supercritical water at 410 and 450 °C, with a high mass ratio of water to pyrolysis oil to ascertain the maximum yields that could be achieved. The results indicate that conversions increased with increasing pyrolysis oil to water mass ratio at high water ratio under supercritical water conditions at 410 °C, gave the highest products conversion of ~91 wt.%, with 28 wt.% heavy oil recovered, ~23 wt.% gas yield, 27 wt.% water generated and approximately 13-14 wt.% of light oil produced. Similar product conversion was obtained using biomass as a feedstock with slightly higher water mass ratio added into the reactor (R1:15), and slightly lower heavy oil yield was recovered (21 wt.%). Gas generation was observed to reach a maximum and then level off at ~22-23 wt.% in near-supercritical water and supercritical water experiments at 410 °C. No further cracking of the heavy oil was observed for experiments at 450 °C, and an increase of 10 wt.% in the gas yield was observed when the temperature was increased to 450 °C (33 wt.%) from 410 °C (23 wt.%) with ~7 wt.% of light oil produced and approximately 24 wt.% of water generated. The oxygen contents of the heavy oil recovered were ~15-16% (for 410 and 450 °C), with H/C atomic values of 1.1. Similar overall conversions were achieved using tetralin with much lower solvent to oil ratios were needed and the liquid products had a slightly lower oxygen content (14%). The estimated hydrogen from water was estimated as ca. 0.3% at 410 and 450 °C in high conversions of pyrolysis oil experiments, and experiments with tetralin/1-methyl naphthalene provide evidence that a small amount of hydrogen was sufficient to achieve high product conversion, giving an increase of H element content from 7.0% to 7.3%. [ABSTRACT FROM AUTHOR]

Miscanthus conversion to bio-fuels was investigated using sub- and supercritical water at 410 and 460 °C with high mass ratios of water to biomass to ascertain the maximum yields that could be achieved. The results indicate that conversions increased with increasing miscanthus to water mass ratio at high water ratio and 410 °C to give the highest conversions of ∼90 wt.%, producing ∼21 wt.% heavy oil, ∼27 wt.% gas, ∼28 wt.% water and ∼12 wt.% light oil. At 460 °C, the maximum conversion was similar but the liquid product was lighter with only 7% heavy oil and more hydrocarbon gas being obtained. The oxygen contents of heavy oil recovered ∼12–16% (for 410 °C and 460 °C), with H/C ratio of 1.09 at 410 °C. Under equivalent conditions with tetralin as a model hydrogen-donor solvent, similar overall conversions were achieved but with much lower solvent to miscanthus mass ratios were needed and the liquid products have lower oxygen contents (∼13%). Reduced CO and increased CO 2 yields provide evidence that water hydrogen is being utilised but the estimated amounts of ca. 0.5% at 410 and 460 °C are considerably lower than with hydrogen-donor solvents which account for the lower yields of bio-oils and their higher oxygen contents. [ABSTRACT FROM AUTHOR]

Abstract: Catalytic hydropyrolysis was used to release the aliphatic biomarkers covalently bound within the asphaltene structure of highly biodegraded Nigerian tar sand bitumens. Unlike the free aliphatic hydrocarbons extracted from the bitumen, the hydropyrolysis products of the asphaltenes afford aliphatic biomarkers having the characteristics of the initial unaltered oil, which had been trapped within the asphaltene matrix of the bitumen and protected from biodegradation processes. The biomarker profiles obtained allow proper characterisation of the bitumen in terms of source and thermal maturity. Catalytic hydropyrolysis is also capable of releasing aromatic hydrocarbons that can be used in the geochemical characterisation of the bitumen. [Copyright &y& Elsevier]

In this study, pyrolysis of sawdust and pinewood (120–250 μm) was conducted in a drop-tube furnace (DTF) at temperatures of 900, 1100, 1300 °C and residence times of 50–600 ms in both CO 2 and N 2 atmospheres. The samples are fed at a rate of 5–10 g/h in a gentle flow of nitrogen (1 L/min) to ensure laminar flow. A silica tracer method has been developed to accurately determine the high temperature volatile matter yields. The elemental analysis of chars collected allowed the study of the release of nitrogen. BET surface area, scanning electron microscope (SEM) and X-ray diffraction (XRD) analyses were also carried out to study the chars produced. Burnout tests were conducted at 1100 °C, an O 2 concentration of 5% v/v in N 2 and CO 2 respectively, using the chars produced at the same temperature and a residence time of 200 ms. In nitrogen, the maximum volatile yield achieved was 97 wt% while in CO 2 , the maximum volatile yield was over 99 wt% for residence times above 200 ms, indicating virtually complete gasification of the char. These are the highest reported volatile matter yields for biomass obtained using a DTF. The release of nitrogen into the volatile phase is proportional to the yield of volatiles both for air and oxy-fuel conditions. SEM images revealed higher porosities of the DTF CO 2 chars than those of N 2 , being consistent with their higher BET surface areas. Faster char burnout was obtained for oxy-fuel firing attributable to the CO 2 /char gasification reactions. The results will be useful for modeling dedicated oxy-biomass firing and co-firing systems. [ABSTRACT FROM AUTHOR]

In order to ascertain whether kerogen and the heavy oil or bitumen generated during the initial stages of source rock maturation then go on to produce similar gas yields compared to the natural situation when they are present in source rocks, a study has been conducted on an immature type II Kimmeridge Clay Formation (KCF) source rock (Dorset, United Kingdom), with an initial vitrinite reflectance (VR) of 0.31% Ro and total organic carbon (TOC) content of 14.4%. Water (hydrous) pyrolysis experiments were conducted on the whole immature source rock, the isolated partially matured bitumen-extracted source rock and the isolated bitumen (bitumen generated and extracted from the initial source rock) and mixtures of the isolated partially matured source rock and bitumen using a 22ml Hastalloy vessel at 320–420°C for 7–48h over a pressure range of 115–500bar. Hydrocarbon gas yields and the increase in VR were greater for the whole rock experiments compared to the experiments on the isolated partially matured source rock and isolated bitumen (no mineral matter present), as well as the experiments on mixtures of the isolated partially matured isolated source rock and bitumen combined. Hydrocarbon gas yields and VR values were found to decrease at 500bar compared to 180bar at 350°C where the effects of pressure retardation were found to be much more significant for the partially matured source rock maturation and bitumen in isolation than for the whole source rock. At 420°C, gas generation was not affected by pressure, but VR decreased going from 310bar to 450bar. The results obtained demonstrate that the interplay of inherent mineral matter, reactant phase, source rock/kerogen, bitumen and pressure are key factors in determining the extent of hydrocarbon generation and source rock maturation in geological basins. [ABSTRACT FROM AUTHOR]

In an effort to reduce CO 2 emissions from solid fuels, a considerable amount of research is going into how improve the manufacturing processes and product properties of the products from pyrolysis. One aspect that is often overlooked is the production of charcoal for cooking and soil remediation, which is an inefficient conversion process. There is considerable interest into using additives to increase charcoal yields, and based on the observation from fast pyrolysis work that certain catalyst tar cracking pathways can deposit considerable amounts of coke on the surface of the catalyst, there is a potential application to slow pyrolysis processes producing charcoal. Alumino-silicate catalysts have been shown to have a relatively high tendency to do this. This work hypothesises that this catalysation can be applied to slow pyrolysis, with low cost alumino-silicate minerals, specially bentonite clay, which has been added to pine pyrolysis in concentrations up to 60%wt (against input biomass) at temperatures 300–700 °C. This study has shown that the use of bentonite clay minerals can be beneficial to the process, as there is an increase in the charcoal yield from biomass, whilst the proximate analysis of the charcoal shows little change from levels expected from biomass only pyrolysis. The conversion of oil to charcoal was more effective at high temperatures due to higher levels of oil cracking. At 700 °C with 60% clay loading, charcoal yield increased 16%wt (dry ash free basis) was seen, while at the same time 19% extra gas was produced at the expense of 35% of the oil from raw pine pyrolysis. This indicates fuel properties of the charcoal are predictable, and changes in yield considerable. At the same time, the abundance of lower molecular weight oils is increased (relative to 4-methyl phenol). It is though that pyrolysis oil reacts with the clay, causing the heavier tars to disproportionate into charcoal and gas. [ABSTRACT FROM AUTHOR]

Poly(ethylene imine) is a family of polymers with a high content of amine groups employed in various applications and widely investigated as CO 2 adsorbents in carbon capture and sequestration. In this study, five branched polyethylenimines (PEIs) of different molecular weights were analysed by Py-GC-MS to gather information on the chemical structure of the principal thermal degradation products. All the PEIs produced pyrolysates with a similar chemical composition characterised by the occurrence of ethylenediamine, diethylenetriamine, piperazine, N -ethylaminepiperazine, pyrazine, 2-methylpyrazine, 2,3-dimethylpyrazine, 2-ethylpyrazine. Oligomeric ethylene polyamines were volatilised or evolved after chain scission of the PEI backbone. Pyrolysates also contained minor amounts of alkylated pyrroles, imidazoles, pyridines and other compounds that could not be identified. Pyrolysis products were formed at 300 °C, and their abundance increased markedly from 400° to 600°C. Pyrolysis of PEIs at 500 °C in the presence of mesoporous silica favoured cyclisation and aromatisation, enhancing the production of alkylated pyrazines. These compounds are of potential interest in the food industry as flavour-enhancing additives. • Thermal degradation products of branched polyethyleneimines PEI revealed by Py-GC-MS. • Oligomeric linear polyamines, piperazines, pyrazines principal products at 300–600 °C. • Slight changes of pyrolysate composition of PEI with different MW. • Silica enhanced the pyrolytic formation of alkylated pyrazines. [ABSTRACT FROM AUTHOR]

Agroenvironmental benefits and limitations of biochar in soil applications require a full understanding of the stability and fate of the various carbon fractions. Analytical hydropyrolysis (HyPy) enables the determination of the stable black carbon (BC HyPy ) and thermally labile (semi-labile; non-BC HyPy ) fractions in biochar and soil samples. The non-BC HyPy fraction can be analysed at a molecular level by gas chromatography-mass spectrometry (GC-MS). In the present study, HyPy was applied to the characterisation of biochars produced from pine wood, beech wood and corn digestate with the same pyrolysis unit at low (340–400 °C) and high (600 °C) temperatures. Results were compared with those from Py-GC-MS. HyPy provided consistent information concerning the thermal stability of biochar samples, with BC HyPy levels related with the relative abundance of the charred fraction estimated by Py-GC-MS and the hydrogen/carbon (H/C) ratios. The non-BC HyPy fractions were featured by the presence of polycyclic aromatic hydrocarbons (PAHs) from two to seven rings, including alkylated derivatives up to C 4 . Partially hydrogenated PAHs were also detected. The yields of non-BC HyPy were higher for those biochars produced at lower temperatures and always more abundant than the levels of solvent-extractable PAHs. The methylated/parent PAH ratios from HyPy and Py-GC-MS exhibited lower values for the most charred biochar. The observed differences in the abundance of the stable fraction and the molecular chemistry of the semi-labile fraction can be usefully utilised to drive the process conditions to the desired properties of the resulting biochars and to predict the impact of biochar amendment to soil organic pools. The concentrations of priority PAHs in the semi-labile fraction was evaluated in the mg g −1 level suggesting that it could be an important fraction of the polyaromatic carbon pool in soil. [ABSTRACT FROM AUTHOR]

Bio-oils produced by processes such as slow or fast pyrolysis typically contain high water and oxygen contents, which make them incompatible with conventional fuels. It is therefore necessary to upgrade the bio-oils to reduce their oxygen and water contents. The bio-oil upgrading process can consume up to 84 wt% of the initial bio-oil it is therefore important to develop other alternative approaches to generate high quality bio-oil. Thermolytic liquid solvent extraction (LSE) has been considered as a potential viable process due to the high liquid yield, better product quality and water free nature of the final products. In this study, a novel LSE process of biomass liquefaction has been studied under various conditions of solvent type, temperature, and biomass species. Compared to currently available commercial pyrolysis approaches, this process using tetralin as a solvent is shown to be capable of generating high quality bio-oil with low oxygen contents (ca. 5.9%) at extremely high overall conversions of up to 87 and 92 (%) dry and ash free basis (DAF) from Scotch pine and miscanthus, respectively. Overall, the study has demonstrated the advantages of LSE for bio-oil generation from biomass, in terms of producing high conversions to liquid products that are compatible with existing petroleum heavy feedstocks. [ABSTRACT FROM AUTHOR]

Abstract: Microscale sealed vessel pyrolysis (MSSVpy) and catalytic hydropyrolysis (Hypy) combined with gas chromatography–mass spectrometry have emerged in recent years as useful and versatile organic analytical and characterisation methods. Both now commercially available, these pyrolysis methods complement traditional flash pyrolysis analysis which can be limited by excessive degradation or inadequate chromatographic resolution of pyrolysates of high structural polarity. To assess the versatility and merits of these two pyrolysis methods they were separately applied to several organic samples reflecting different thermal maturities. This comparison revealed many product similarities, but also several important features unique to each. Both produced C27–C33 hopane products from a bacterial isolate and a membrane biofoulant from a water filtration system. Increased concentrations of higher MW and ββ-stereoisomeric hopanes detected by Hypy reflect more selective bond cleavage, attributed to a relatively short residence time and catalyst assisted reduction of volatilisation temperatures, of the mostly C35 (ββ-) bacteriohopanepolyol precursors established by corresponding LC–MS analysis. When applied to the asphaltene fraction of a biodegraded oil both pyrolysis methods were able to regenerate similar distributions of liquid n-alkanes and source diagnostic hopane and sterane biomarkers removed from the free phase of oil by the biodegradation. The detection of low MW (

A sequential degradation scheme, involving solvent extraction, alkaline saponification and catalytic hydropyrolysis (open-system pyrolysis assisted by high hydrogen gas pressure), was used for recovering both free and covalently-bound lipid organic compounds from two archaeological ceramic sherds sampled from the interior of cooking vessels and from a ceramic control sample used for cooking modern milk. Various organic molecular products released by this regime were identified and quantified using gas chromatography–mass spectrometry (GC–MS), and the stable carbon isotopic (δ13C) values of the major products were measured using gas chromatography–combustion–isotope ratio mass spectrometry (GC–C–IRMS). Significant amounts of fatty acids and fatty acid-derived hydrocarbons could be released by alkaline hydrolysis and hydropyrolysis, respectively, following initial solvent extraction of the ceramic. No significant lipid signal bias, in terms of both carbon number distributions of compounds or stable carbon isotopic signatures, could be discerned though between free, hydrolysable and tightly-bound molecular components in this study. So, conventional analysis of free fatty acid components appears, from this limited data set, to provide an accurately representative insight into the total fatty acid composition in archaeological pots. Even after catalytic hydropyrolysis, a significant amount of residual carbon (>50 wt.% of the total organic carbon) remained on the archaeological sherds in the form of highly condensed aromatic polymers, with much lower (6 wt.%) levels of residual carbon persisting in the control pot. This aromatic macromolecular phase on the vessel interior most probably originates from repeated use of the vessels for cooking, via gradual polymerisation/aromatisation of food residues, rather than being derived from smoke condensates produced from cooking on open wood fires. The co-existence of preserved aliphatic fatty acids and a thermally-stable aromatic macromolecular phase within the same ceramic matrix suggests that the preserved lipid components were introduced into the vessel after the formation of the bulk of the char, and so fatty acid analyses most probably provide information concerning the later uses of archaeological pots prior to burial. [Copyright &y& Elsevier]