Catalytic Hydropyrolysis Research Articles

Transformations of biomass internal oxygen at varied pyrolysis conditions

Pine bark, characterized by high oxygen content (41 wt.%) typical of biomass, was submitted to pyrolysis at varied conditions in order to follow the regularities of oxygen transformation. The effect of water, a catalyst and molecular hydrogen on the yield and composition of pyrolysis products, and their oxygen content were studied. The volatiles, liquid fractions soluble in selected solvents, and solid products of pyrolysis were characterized by ultimate analysis, FTIR-spectroscopic and chromatographic methods. It was demonstrated that, depending on pyrolysis conditions, 46–79 wt.% of oxygen of the original biomass can be transformed into water and 17–43 wt.% into CO 2. The maximum amount of water is produced at catalytic hydropyrolysis, and the maximum amount of CO 2 at pyrolysis with supercritical water. The yields of total bio-oil and charcoal with considerably reduced oxygen content were 11–19 and 30–41 wt.%, respectively. Though a significant portion of oxygen compounds was separated by extraction with polar solvents like water and acetone, the benzene-soluble oil fraction was characterized by a wide spectrum of oxygenates as well. As for the biomass, the role of oxygen in both quantitative and qualitative pyrolytical transformations is dominant being strongly influenced by pyrolysis conditions.

The use of model compounds to investigate the release of covalently bound biomarkers via hydropyrolysis

This study describes the reduction of functionalised model compounds to their corresponding hydrocarbons by catalytic hydropyrolysis to provide information on the release of biomarkers from kerogens and asphaltenes covalently bound through the functional groups investigated. Five model compounds were investigated, the n-C 18 carboxylic acids, stearic and oleic acids; the C 24 steroidal acid, 5β-cholanic acid; and the saturated and unsaturated C 27 sterols, 5α-cholestanol and cholesterol. The yield and distribution of the hydrocarbons generated were assessed for the model compounds adsorbed to silica and carbon substrates, and unsupported on a bed of catalyst. The n-C 18 acids are shown to be reduced to the n-C 18 alkane, with a selectivity of >95% for stearic acid, although due to its unsaturated structure, oleic acid is prone to cracking, with shorter chained n-alkanes also being formed. The conversion of these compounds, adsorbed to either silica or carbon is relatively low, even at hydropyrolysis temperatures significantly above their boiling point, suggesting that interactions between the acids and substrate leading to the formation of stable entities (Si–O–C linkages in the case of silica) significantly retard volatilisation. The yield can be increased by placing the compounds directly onto a bed of catalyst, but for low boiling compounds such as stearic acid this can result in volatilisation and cracking at temperatures below that of the activation point of the catalyst. This method produced improved yields of >95% pure product for higher boiling compounds such as 5β-cholanic acid. The presence of the functional group attached to the ring system of compounds such as 5α-cholestanol does not diminish the selectivity of the technique. The double bond in cholesterol resulted in more incomplete hydrogenation with sterenes being generated, and in addition to 5α and 5β-cholestane, diasteranes were also generated via migration of the double bond.

Mild catalytic hydropyrolysis of high-viscosity, high-sulfur crude oil

The possibility of increasing the light cut content during mild catalytic hydropyrolysis of high— viscosity, high—sulfur crude oil was investigated. The new technology allows attaining a greater than 60 wt. % yield of motor fuels due to decomposition of resins and asphaltenes without expensive catalysts. The <350°C cut obtained can be used without hydrotreating for synthesis of environmentally safe motor fuels.

05/00960 The potential of bound biomarker profiles released via catalytic hydropyrolysis to reconstruct basin charging history for oils

05/00960 The potential of bound biomarker profiles released via catalytic hydropyrolysis to reconstruct basin charging history for oils

Hydropyrolysis of algae, bacteria, archaea and lake sediments; insights into the origin of nitrogen compounds in petroleum

Nitrogen compounds are ubiquitous in fossil fuels and yet our understanding of their origins in the geosphere is limited. In this study, high hydrogen pressure pyrolysis was performed on sample material representing potential contributors to sedimentary organic matter (algae, bacteria and archaea) and sediments representing early diagenetic accumulations from Lake Pollen (Norway) and Priest Pot (UK). Previous workers demonstrated the structurally conservative nature of high hydrogen pressure pyrolysis in that the technique maximizes the yields of covalently bound hydrocarbon biomarkers from organic matter without adversely affecting their stereochemistry ( Love et al., 1995). Release of covalently bound biomarkers in high yields from kerogen via catalytic hydropyrolysis. In this study, the types and distributions of organic nitrogen compounds in the hydropyrolysates were characterised under similar conditions to such experiments where biomarker hydrocarbons undergo minimal rearrangement. Compounds identified by gas chromatography–mass spectrometry included alkyl-substituted indoles, carbazoles, benzocarbazoles, quinolines and benzoquinolines. Indoles are present in all hydropyrolysates, suggesting a common origin. A potential source of indoles is represented by tryptophan which was shown to degrade through a series of alkylated intermediates to indole. Carbazole, quinoline and benzoquinoline were also found in the hydropyrolysates of algae, bacteria and archaea. The presence of these petroleum-related nitrogen compounds in hydropyrolysates generated from biomass suggests an early origin for petroleum nitrogen compounds. A potential source of naturally occurring nitrogen compounds such as that in the alkaloids has yet to be realised. Benzocarbazoles were absent from hydropyrolysates of algae, bacteria and archeae, but present in those from recent sediments, suggesting their presence may be related to processes occurring during early diagenesis at, or immediately below, the sediment–water interface. In sediments from Lake Pollen, changes in the benzocarbazole ratio [ a]/([ a] + [ c]) ratio coincides with the interval described as a transition from fjord to lake environment, suggesting that benzocarbazoles are sensitive to changes in depositional environment and may have potential to act as a marker for environmental conditions.

A catalytic hydropyrolysis method for the rapid screening of microbial cultures for lipid biomarkers

A catalytic hydropyrolysis procedure was developed for rapidly assessing the relative abundances and variety of different biomarker lipid structures in microbial cultures by reductively converting free functionalised and polymeric lipids within whole cells into hydrocarbons. High pressure hydrogen gas and a molybdenum catalyst were used to target and cleave carbon–oxygen covalent bonds (particularly ester, alcohol, acid and ether) and the pyrolysis process was conducted in an open-system reactor configuration to minimise structural and stereochemical rearrangements in the products. A revised experimental protocol, involving a modified catalyst-loading procedure, careful use of a silica support substrate and a revised temperature program was tested and optimised for handling biomass. Partial hydrogenation of double bonds inevitably did occur although it was found that some unsaturation was preserved, particularly within branched and polycyclic hydrocarbon structures. This experimental approach aids our ability to optimally correlate fossil biomarker signals found in the sedimentary record with their lipid precursors found in extant organisms. Our technique complements more rigorous, but time-consuming, chemical approaches used for elucidating the exact chemical structures of intact functionalised lipids by providing a rapid means by which to screen microbial cultures.

The potential of bound biomarker profiles released via catalytic hydropyrolysis to reconstruct basin charging history for oils

Catalytic hydropyrolysis performed in a fixed bed reactor using high hydrogen gas pressures (>10 MPa) has the unique ability to release high yields of biomarker hydrocarbons from macromolecular organic fractions in petroleum source rocks and crude oils whilst minimising alteration to their isomeric distributions. One potential application of such bound biomarker profiles, which is the subject under investigation here, is to act as molecular tracers to aid the reconstruction of secondary migration pathways of oils in basins as well as reservoir filling histories. Our hypothesis is that bound biomarker compounds released from the adsorbed asphaltenes from core petroleum samples along a known migration pathway reveal the maturity and source characteristics of the first oil that came into contact with the carrier substrate. The primary investigation was performed on the Blake Field (Outer Moray Firth, UK North Sea, blocks 13/24 and 13/29), where the solvent-extractable biomarker hydrocarbon distributions exhibit no significant variations throughout the reservoir, offering little information as to reservoir filling events. Bound biomarker characterisation obtained by the hydropyrolysis of the adsorbed asphaltene fractions not only displayed lower overall maturities than the hydrocarbon biomarkers, but significantly exposed a discrete positive trend of maturity emanating from a location in the northwest part of the field which, if the original hypothesis is correct, possibly indicates the location where oil first entered the reservoir. Supplementary information obtained from laboratory experiments where two oils of subtly different composition (in terms of bound biomarker profiles) were consecutively passed through core substrates under anhydrous and hydrous conditions, and eluted with solvents of increasing polarity, revealed that the most strongly adsorbed asphaltenes exhibited bound biomarker distributions indicative of approximately 70 wt% of asphaltenes from the original oil retained on the core substrate, which is compatible with the hypothesis.

04/01359 Application of catalytic hydropyrolysis for the rapid preparation of lignin concentrates from wood: Beramendi-Orosco, L. E. et al. Organic Geochemistry, 2004, 35, (1), 61–72

04/01359 Application of catalytic hydropyrolysis for the rapid preparation of lignin concentrates from wood: Beramendi-Orosco, L. E. et al. Organic Geochemistry, 2004, 35, (1), 61–72

Stable carbon isotopic characterisation of free and bound lipid constituents of archaeological ceramic vessels released by solvent extraction, alkaline hydrolysis and catalytic hydropyrolysis

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 ( δ 13 C ) 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.

03/02107 Product analysis of catalytic multi-stage hydropyrolysis of lignite: Li, W. et al. Fuel, 2003, 82, (5), 569–573

03/02107 Product analysis of catalytic multi-stage hydropyrolysis of lignite: Li, W. et al. Fuel, 2003, 82, (5), 569–573

Application of catalytic hydropyrolysis for the rapid preparation of lignin concentrates from wood

The use of hydropyrolysis (hypy) is described as a potentially rapid procedure for obtaining lignin-enriched residues from wood for either simply estimating lignin content or for performing stable isotope ratio measurements. Hypy was carried out on samples of oak wood and, as reference materials, Klason lignin and pure cellulose over the temperature range of 200–500 °C. The composition of the residues were assessed by solid-state 13C NMR. At 300 and 350 °C, the extents of conversion achieved for cellulose was 88 and 95% respectively, indicating that highly lignin-enriched residues should be obtained for wood samples. This was confirmed by solid-state 13C NMR which also indicated that any remaining cellulose had aromatised to a significant extent. In addition, hypy caused quite extensive demethylation of methoxyl functionalities and cleavage of the characteristic β- O-4 ether lignin linkage. Finally, correcting the 300 and 350 °C hypy residues for residual cellulose gave estimates of the lignin content for oak wood in close agreement with those obtained by the Klason method and by solid-state 13C NMR. At 350 °C, the residual cellulose accounts for ca. 30% of the lignin concentrate obtained from hypy.

Recycling by pyrolysis of thermoset composites: characteristics of the liquid and gaseous fuels obtained

Catalytic hydropyrolysis (HP) of crop straw and used engine oil (UEO) alone and co-HP of crop straw and UEO were conducted. Crop straws with higher cellulose contents and cellulose-to-hemicellulose mass ratios produced higher oil yield in the HP process. Positive synergistic effect between crop straw and UEO was observed for improving the pyrolysis oil yield and reducing coke formation and N and S content during their co-HP process. Compared with the oils produced from the HP of crop straw alone, the oils obtained from the co-HP of crop straw and UEO possessed higher H content, HHVs, and effective hydrogen (H/Ceff) value, and significantly lower N and S contents (12−887 mg L−1 and 16−112 mg L−1, respectively). Strong synergistic effect between crop straw and UEO for the removal of S rather than N was observed during co-HP. Co-HP was found to slightly increase the abundances of lighter compounds in the oils compared with that of HP of crop straw alone. Co-HP of crop straw and UEO also resulted in a clearly higher energy recovery (73.26–83.45 %) than the HP of crop straw alone (30.95–67.95 %). The pyrolysis oil produced from the co-HP process was divided into centrifugal oil (C-oil) and extraction oil (E-oil), and the C-oils had much lower N and S contents (12−57 mg L−1 and 16−24 mg L−1, respectively) than the E-oils (445−887 mg L−1 and 71−112 mg L−1, respectively). Moreover, the C-oils also exhibited slightly higher saturated hydrocarbons content and lower aromatic compounds content than the E-oils.

Release of organic nitrogen compounds from Kerogen via catalytic hydropyrolysis

High hydrogen pressure pyrolysis (hydropyrolysis) was performed on samples of solvent extracted Kimmeridge Clay Formation source rock with a maturity equivalent to ca. 0.35% vitrinite reflectance. We describe the types and distributions of organic nitrogen compounds in the pyrolysis products (hydropyrolysates) using GC-MS. Compounds identified included alkyl-substituted indoles, carbazoles, benzocarbazoles, quinolines and benzoquinolines. The distributions of the isomers of methylcarbazoles, C2-alkylcarbazoles and benzocarbazoles in the hydropyrolysates were compared to a typical North Sea oil. The hydropyrolysates compared to the North Sea oil, showed increased contributions from alkylcarbazole isomers where the nitrogen group is exposed (no alkyl substituents adjacent to the nitrogen functionality) and appreciable levels of benzo[b]carbazole relative to benzo[a]- and benzo[c]carbazoles. Hydropyrolysis is found to be an ideal technique for liberating appreciable quantities of heterocyclic organic nitrogen compounds from geomacromolecules. The products released from the immature Kimmeridge Clay are thought to represent a potential source of nitrogen compounds in the bound phase (kerogen) able to contribute to the free bitumen phase during catagenesis.

Release of organic nitrogen compounds from kerogen via catalytic hydropyrolysis

Release of organic nitrogen compounds from kerogen via catalytic hydropyrolysis

99/00640 Effect of dust type and operating conditions on the performance of high-temperature ceramic filters

Fixed-bed hydropyrolysis tests have been conducted on a UK bituminous coal (Gedling), the Wyodak Argonne Premium coal sample and the high-sulfur Mequinenza lignite at a pressure of 15 MPa with heating rates of 5 and 300 K min−1. The tar yields and overall conversions increased markedly by ∼5–20 wt% daf coal as the heating rate was decreased from 300 to 5 K min−1 for final temperatures of 520 and 600°C, both with and without a sulfided molybdenum catalyst. Conversions of > 90 wt% were achieved with slow heating in catalytic hydropyrolysis for all three coals. The small increases in gas yield indicated that tar-forming as opposed to hydrogasification reactions are promoted by slow heating. These results demonstrate the value of slow heating for analytical applications of hydropyrolysis, which include the determination of organic sulfur forms and the covalently bound biomarker hydrocarbons in coals and petroleum source rocks.

Free and bound fatty acid oxidation products in archaeological ceramic vessels

While oxidation products of unsaturated fatty acids, for example dicarboxylic acids (hereafter diacids), must form during the use of unglazed ceramic vessels for the processing of animal and plant products, such components have never been observed during studies of absorbed lipids. Their absence from the extractable lipid fraction is presumed to be the result of their loss from potsherds through groundwater leaching. Lipid oxidation products including short-chain dicarboxylic acids, ω-hydroxy acids and longer-chain hydroxy and dihydroxy acids have now been observed as components probably covalently bound into solvent insoluble residues of potsherds recovered from waterlogged deposits. These components were only revealed following alkaline treatment of the insoluble residues. A similar mixture of diacids was observed in high abundance in the free lipid fraction of vessels recovered from an exceptionally arid deposit where groundwater leaching would never have occurred. These results confirm the formation of oxidation and probable polymerization products of unsaturated fatty acids during vessel use and burial.

A Novel Hydropyrolysis Approach for Optimum Release of Covalently-Bound Biomarker Hydrocarbon Skeletons from Sedimentary Organic Matter

In order to generate more representative biomarker profiles, geomacromolecules must first be fragmented into smaller (readily-analysable) structural units to gain access to the covalently-bound pool of biomarkers. Existing chemical degradation and pyrolysis methods for fragmenting and analysing molecular components of kerogen are notoriously poor at providing quantitatively significant and/or accurate data. Chemical degradation methods have been less successfully and less widely applied to kerogen in comparison with solvent-soluble macromolecular fractions (usually applied to polar fractions). In general, since the polar fractions represent only a small proportion of the total OM and the yields of routinely analysable products obtained from chemolysis are low, it follows that the biomarker profiles produced from chemical degradation may also be highly biased with respect to the total biomarker assemblage. With analytical pyrolysis methods, e.g. Py-GC-MS, higher conversions of kerogen can be achieved but the structural information about the molecular constituents that is provided (and hence the accuracy of biogeochemical information that is conveyed) is compromised to a significant extent due to the appreciable secondary reactions (cracking and isomerisation) of released products which manifest at the high pyrolysis temperatures employed (typically >600~ In order to generate more representative biomarker profiles, a far higher proportion of the biomarker constituents must be accessed. Reaction conditions are sought which solubilise a significant proportion of sedimentary OM (approaching 100% conversion), whilst maxiraising the level of structural (biogeochemical) information and minimising the extent of secondary reactions between degradation products. Pyrolysis at high hydrogen pressures (> 10 MPa, hydropyrolysis) eliminates the problem of low yields often associated with the use of sterically-bulky chemical reagents and limits the extent of retrogressive chemistry (leading to char-formation and rearrangement of detectable products) encountered in other analytical pyrolysis methods (e.g. flash-pyrolysis). Fixed-bed hydroyrolysis in the presence of a dispersed sulphided molybdenum catalyst gives rise to overall carbon conversions greater than 85% for petroleum source rocks (Type I and Type II ancient SOM) and high volatile coals (Type III OM), with high selectivities to dichloromethane-soluble tar and low hydrocarbon yields (Roberts et al., 1995). Previous work has demonstrated the unique ability of fixed-bed catalytic hydropyrolysis to release much higher yields of aliphatic biomarker hydrocarbons (including n-hydrocarbons, hopanes, steranes and methyl steranes) from immature kerogens in comparison with solvent extraction, mild catalytic hydrogenation and normal pyrolysis methods (Love et al., 1995, 1996). A combination of slow heating rate (5~ rain1), high hydrogen pressure (15 MPa) and use of a dispersed sulphided molybdenum catalyst represents the best regime for achieving high conversions to dichloromethane-soluble products whilst minimising the structural rearrangement of biomarker species (Love et al., 1997). Staged hydropyrolysis on Goynuk oil shale (NW Turkey, Oligocene, Type I) has confirmed that hopanes released at higher temperatures (above 350~ through cleaving relatively strong bonds (possibly by up to 4 or more ether linkages protected by a macromolecular matrix) are quantitatively more significant than those released at lower temperatures for this immature source rock with a relatively low organic sulphur content (Love et al., 1997). This important pool of (strongly-)bound biomarkers is especially difficult to isolate by existing chemical and thermal degradation methods. The very high yields of products, in combination with the retention of structural information that is observed, dictates that hydropyrolysis will generate a more sensitive and accurate biomarker profile for sedimentary OM than these existing approaches.

High Uptake of Palladium by Bituminous Coals

In view of the interest in catalytic hydropyrolysis and suitable dispersed catalysts, the uptake of palladium has been investigated using three different coals, namely, North Dakota and Mequinenza lignites and Gedling high-volatile bituminous coal

97/03694 Effects of reaction parameters on product yields during coal hydropyrolysis

Catalytic hydropyrolysis (HyPy) was used to release covalently bound aromatic hydrocarbons from both mature and overmature Permian source rocks in the Sichuan Basin, China. The released covalently bound aromatic hydrocarbons were discussed and compared with their free counterparts obtained by Soxhlet extraction. Furthermore, a mature Permian Dalong kerogen was selected for artificial simulation experiments. The HyPy experiments of the above thermal altered kerogens were subsequently conducted. The results from the artificial simulation sequence were also discussed and compared with those from the natural maturity sequence. For both natural maturity sequence and artificial simulation sequence, the distributions of covalently bound methylphenanthrenes and methyldibenzothiophenes are quite similar at different maturity stages. Triaromatic and monoaromatic steroids which are the aromatization products of steroids were not detected in covalently bound aromatics of all samples. The above results indicate that the rearrangement of methyl group on aromatic nucleus and the aromatization of steroids within kerogen was retarded to some extent or even prohibited, due to the protection of macromolecular structure below a vitrinite reflectance of 2.4%. It implies that aromatic maturity-related biomarker parameters based on the rearrangement and aromatization reactions within kerogens are probably not appropriate for maturity assessment. Meanwhile, perylene which is easily altered by thermal alteration was still existent in covalently bound aromatics released from the Dalong Formation even at over mature stage (Ro: 1.8%) and from the thermal altered kerogen until the temperature below of 400 °C (H/C: 0.49). It means the covalently bound perylene can be protected by macromolecular structure from the destruction of thermal stress at least below Ro of 1.8% (or H/C > 0.5). The results obtained also permitted the geochemical characterization of the source rocks.

Effect of Process Variables in Catalytic Hydropyrolysis on the Release of Covalently Bound Aliphatic Hydrocarbons from Sedimentary Organic Matter

Hydropyrolysis has considerable promise for application as an analytical tool for release of biomarker hydrocarbons in high yields with minimal structural rearrangements. In this study, the effect of key reactor variables on the product yield and distribution of alkanes obtained from temperature-programmed fixed-bed hydropyrolysis of a Tertiary oil shale (Goynuk, NW Turkey, classified as a type I kerogen) and a Tertiary lignite (Hambach, Lower Rhine Basin, Germany) has been investigated. A combination of slow heating rate (5 °C/min), high hydrogen pressure (15 MPa), and use of a dispersed sulfided molybdenum catalyst represents the best regime for achieving high conversions to dichloromethane-soluble oil while minimizing the structural rearrangement of biomarker species. Staged hydropyrolysis has confirmed that hopanes released at higher temperatures through cleaving relatively strong bonds are quantitatively more significant than those released at lower temperatures. These findings have reinforced the un...