Thermal Decomposition Of Organic Matter Research Articles

Thermal Behavior of Oil Shale Pyrolysis under Low-Temperature Co-Current Oxidizing Conditions.

The thermal behavior of the Huadian oil shale during low-temperature co-current oxidizing pyrolysis was studied by lab-scale experiments under different basic pyrolysis temperatures and input gas flow rates. The results showed that, in the process of oil shale co-current oxidizing pyrolysis, the increasing input gas flow rates under the same basic pyrolysis temperatures can significantly enhance the heat generation of oil shale. Meanwhile, it can be seen from the temperature variation characteristics of oil shale that the heat released by the oxidation reaction of semicoke and oxygen is enough to support the thermal decomposition of organic matter without supplemental heating. Moreover, it can be concluded from the 92.06% effective recovery of shale oil that a high yield of oil without a significant loss can be achieved. Finally, compared with increasing basic pyrolysis temperatures, the increased input gas flow rates have a more obvious effect on improving the effective recovery of shale oil.

Study on pyrolysis kinetics and reaction mechanism of Beizao oil shale

The evaluation of pyrolysis kinetics and the reaction mechanism of organic matter and mineral matrix for oil shale is a rather difficult work due to the concomitant structure and complicated reactions. The pyrolysis process of Beizao oil shale was studied in a thermogravimetric analyzer at various heating rates with obvious existence of two stages. The kinetic parameters were estimated via a model-free method known as Friedman method and a multistep model-fitting method called Coats-Redfern method. A two-stage reaction model is proposed based on thermogravimetric analysis and the obtained kinetic parameters. The results indicated that the reaction model g(α) = −[ln(1 − α)]2 might be in charge of Stage I, and reaction mechanism for Stage II could be interpreted by g(α) = −[ln(1 − α)]3. Furthermore, the curve of conversion rate α was predicted based on the obtained kinetic parameters, and the reaction parameters and models were validated by an extra heating rates beyond those used to generate them. It was speculated that the two-stage reactions could be attributed to the thermal decomposition of organic matter with bitumen as intermediate in Stage I, and the devolatilization of inorganic components, mainly clay aluminosilicates and calcite, in Stage II.

A comparison of the molecular composition of plant and fungal structural biopolymer standards with the organic material in early cretaceous Ontong Java Plateau Tuff

Earlier investigations have suggested that an extensive deep biosphere with a significant fungal component is present within the sub-oceanic crust. To investigate this further, the organic material in the lithic sections of a sub-oceanic volcaniclastic tuff obtained from the eastern lobe of the Ontong Java Plateau (OJP tuff) were characterised using X-ray photoelectron spectroscopy and thermal hydrolysis and methylation coupled to gas chromatography/mass spectrometry. In the investigation here, the chemical and molecular composition of plant and fungal structural biopolymer standards were characterised using the same techniques and then compared to the organic material from the OJP tuff. This was conducted on untreated material and after hydrous pyrolysis, a process that simulated the physical and thermal decomposition of organic material that occurs during late diagenesis. The characteristics of the organic material in the OJP tuff matched the products of hydrous-pyrolysed chitin. This result suggested that OJP tuff contained organic material that could have been derived from fossilised chitin, implying that the OJP tuff potentially contained the remnants of a microbial community with a fungal component.

Biochar—just a black matter is not enough

What differs biochar from charcoal? The simple answer is that biochar is a carbon-rich product obtained from the thermal decomposition of organic material, at the presence of no or only a bit of oxygen. In principle, the production of biochar is comparable to the production of charcoal, one of the oldest and most established processes developed by mankind. While charcoal is made traditionally from wood, biochar can be based on a wide range of biomass and biomass residues. However, a variety of technologies for the production of biochar has been developed in recent years. The technologies are based on pyrolysis, gasification, or hydrothermal carbonization and are ranging from simple units, like heated steel drums to full automated and controlled processes. Therefore, the obtained products have tremendous differences in its properties and resulting qualities. The quality defines the field of application. To obtain the required quality for each application, the right process must be applied. Consequently, it is not enough only to enrich the carbon content by thermal decomposition of organic material. The production of tailor-made biochar for specific high added–value application is much more complex. In addition, side products like liquid biofuels make business cases stronger. If it is done in the right way, biochar production combined with advanced biofuels can be an economic solution to overcome the problems of climate change. “So for the future of mankind, this black matter might give the light at the end of the tunnel.”

Recycling of waste artificial marble powder using supercritical methanol

Waste artificial marble powder (AMP), a composite material of poly(methyl methacrylate) (PMMA) and aluminum tri hydroxide (ATH; Al(OH)3), was recycled using supercritical fluids, in which the depolymerization and thermal decomposition of organic materials and the dehydration of inorganic substances occur simultaneously. For PMMA depolymerization in AMP, higher temperatures are required than for PMMA alone, because of the ATH in AMP. Moreover, as Al(OH)3 transforms to alumina (Al2O3), the generated water influences the methyl methacrylate (MMA) yield. In supercritical methanol, MMA is a major product, whereas in sub- and supercritical water, methacrylic acid (MAA) is the main product. The highest yield of MMA was obtained at 573 K in supercritical methanol. The excess methanol in supercritical methanol suppresses the hydrolysis of MMA to MAA, a reaction that reduces the yield of MMA in sub- and supercritical water. MMA was depolymerized in supercritical methanol, but when the reaction proceeded further, the yield of MMA decreased due to thermal decomposition and/or other chemical reactions. While ATH was converted to boehmite (AlOOH) in sub- and supercritical water, the transformation of ATH was minimized in supercritical methanol.

Harnessing In Silico, In Vitro, and In Vivo Data to Understand the Toxicity Landscape of Polycyclic Aromatic Compounds (PACs).

Polycyclic aromatic compounds (PACs) are compounds with a minimum of two six-atom aromatic fused rings. PACs arise from incomplete combustion or thermal decomposition of organic matter and are ubiquitous in the environment. Within PACs, carcinogenicity is generally regarded to be the most important public health concern. However, toxicity in other systems (reproductive and developmental toxicity, immunotoxicity) has also been reported. Despite the large number of PACs identified in the environment, research attention to understand exposure and health effects of PACs has focused on a relatively limited subset, namely polycyclic aromatic hydrocarbons (PAHs), the PACs with only carbon and hydrogen atoms. To triage the rest of the vast number of PACs for more resource-intensive testing, we developed a data-driven approach to contextualize hazard characterization of PACs, by leveraging the available data from various data streams (in silico toxicity, in vitro activity, structural fingerprints, and in vivo data availability). The PACs were clustered on the basis of their in silico toxicity profiles containing predictions from 8 different categories (carcinogenicity, cardiotoxicity, developmental toxicity, genotoxicity, hepatotoxicity, neurotoxicity, reproductive toxicity, and urinary toxicity). We found that PACs with the same parent structure (e.g., fluorene) could have diverse in silico toxicity profiles. In contrast, PACs with similar substituted groups (e.g., alkylated-PAHs) or heterocyclics (e.g., N-PACs) with varying ring sizes could have similar in silico toxicity profiles, suggesting that these groups are better candidates for toxicity read-across analysis. The clusters/regions associated with certain in silico toxicity, in vitro activity, and structural fingerprints were identified. We found that genotoxicity/carcinogenicity (in silico toxicity) and xenobiotic homeostasis and stress response (in vitro activity), respectively, dominate the toxicity/activity variation seen in the PACs. The "hot spots" with enriched toxicity/activity in conjunction with availability of in vivo carcinogenicity data revealed regions of either data-poor (hydroxylated-PAHs) or data-rich (unsubstituted, parent PAHs) PACs. These regions offer potential targets for prioritization of further in vivo assessment and for chemical read-across efforts. The analysis results are searchable through an interactive web application (https://ntp.niehs.nih.gov/go/pacs_tableau), allowing for alternative hypothesis generation.

Ionic Cross-Linking Fabrication of Chitosan-Based Beads Modified with FeO and TiO2 Nanoparticles: Adsorption Mechanism toward Naphthalene Removal in Seawater from Cartagena Bay Area.

Polycyclic aromatic hydrocarbons (PAHs) are complex molecules produced by the thermal decomposition of organic matter in anthropogenic activities. Novel composites with enhanced physicochemical properties aim to overcome limitations such as adsorption capacity, affinity, and stability for PAHs adsorption. Composites based on chitosan are promising due to the good biocompatibility and adsorption properties. This study focuses on the facile preparation of chitosan beads modified with iron oxide (FeO) and titanium dioxide (TiO2) nanoparticles via ionic cross-linking (Ch-FeO/TiO2). FeO and TiO2 were synthesized performing co-precipitation and green chemistry methods, respectively. The characterization evidenced the formation of Ch-FeO/TiO2 with good crystallinity, excellent thermal stability, and superparamagnetic response, attributed to the presence of FeO and TiO2 nanoparticles. High thermal stability up to 270 °C was related to the cross-linked chitosan network. The enhanced adsorption mechanism of Ch-FeO/TiO2 was determined by removing naphthalene from water and seawater samples. The Ch-FeO/TiO2 showed a higher adsorption capacity of 33.1 mg/g compared to 29.8 mg/g of the unmodified chitosan (un-Ch) beads. This is due to the higher functional surface area of 27.13 m2/g, compared to that of 0.708 m2/g for un-Ch. We found a rapid adsorption rate of 240 min and the maximum adsorption capacity of 149.3 mg/g for Ch-FeO/TiO2. A large number of actives sites allows for increasing the naphthalene molecules interaction. Adsorption in seawater samples from Cartagena Bay (Colombia) exhibits an outstanding efficiency of up to 90%. These results suggest a promising, cheap, and environmentally friendly composite for remediation of water sources contaminated with complex compounds.

Using Field-Effect Gas Sensors for Monitoring H2 in Transformer Oil

Introduction Hydrogen can be released during the thermal decomposition of organic materials; therefore, monitoring its level in the working industrial high-voltage transformer oil allows you to identify the development of degenerative processes in advance, because these processes can lead to an accident in the future. In experiments has shown that highly sensitive and small-sized field effect gas sensor based on the metal-insulator-semiconductor (MIS) structure can be used for measuring of H2 in oil with direct contact of its structure with transformer oil. Hydrogen Diffusion in Transformer Oil Numerical estimates show that with the diffusion coefficient D = 4*10-9 m2/s [1] (at room temperature), the time required for H2 saturation in a transformer oil with 10 cm depth to a level 0,9C0 is more than 1 year. In reality, there are convective flows occurred due to the temperature gradient which are combined with diffusion. Nevertheless, such a large diffusion time must be taken into account when designing the experimental setup and the obtained results interpreting. Field-Effect Gas Sensor A schematic representation of the field-effect gas sensor is shown on Figure 1 and described in work [2]. The measuring H2 concentration with the field-effect gas sensor is as follows. When hydrogen molecules from the external environment interact with the metal electrode, H2 molecules decompose into atoms and diffuse to the metal-insulator interface. It is known that on the surface of palladium hydrogen atoms have a dipole moment. The electric field of dipoles leads to a change in the electric field in the dielectric and in the surface layer of the semiconductor. As a result, the capacitance of the MIS-structure changes, the value of which is fixed by the electronic unit while maintaining a constant bias voltage on the MIS-structure. Results and Conclusions The setup used in experiment (Fig. 2) provides similar to a transformer conditions of H2 diffusion. Both field-effect sensors were preliminarily calibrated for H2 in air (in the concentration range 5-100 ppm) at the sensing element temperatures of 23 and 100°С. The optimal temperature of the sensor structure is 100-150°C. However, in experiments, the main sensor could not be maintained at this temperature due to intense heat exchange with oil. For this reason, its heating element was turned off and equal to the temperature of the oil and was 23°C. The reference sensor was maintained at a temperature of 100°C. Relative humidity above oil was 25%. The experiment was carried out as follows. Through drainage tubes, fixed H2 concentrations in the range from 5 ppm to 100 ppm were fed into the container. After the mixture was supplied, the tubes were blocked and, subsequently, the H2 concentration in the vessel was monitored by sensor (Fig. 2 (3)). To accelerate the process of oil saturation with H2, a mixing device was used, the rotation frequency of which was selected to exclude the formation of air bubbles in the oil. Figure 3 shows the dependence of the response of the sensors (main and reference) on the concentration of H2. Table 1 shows the measurement results.The experiment showed that the temperature of the sensor has a significant effect on the detection time of H2. Immersion of the sensor in oil leads to an increase in the noise level of the signal and a decrease in the sensitivity of the sensor in the low concentrations range. Also, the presence of transformer oil does not change the functional dependence of the sensor capacity on the H2 concentration. The response time to H2 is significantly less than the time of its diffusion in oil, which makes it possible to use the sensor as a sensitive element in the control systems for the level of dissolved H2 in the oil of a working transformer. Acknowledgment This work was funded by the Russian Science Foundation under Grant no 18-79-10230 from 08.08.2018.

Origin of hydrocarbon and non-hydrocarbon (H2S, CO2 and N2) components of natural gas accumulated in the Zechstein Main Dolomite (Ca2) strata in SW part of the Polish Permian Basin: stable isotope and hydrous pyrolysis studies

The genetic identification of natural gas accumulated in the Zechstein Main Dolomite (Ca2) strata in the SW part of the Polish Permian Basin (PPB) was determined by means of analytical and experimental methods of petroleum geochemistry including molecular and isotopic compositions, i.e. δ13C of C1–C5 hydrocarbon gases and CO2, δ2H of C1–C3 hydrocarbon gases and δ34S of H2S of natural gas and gases generated during hydrous pyrolysis (HP) experiments and δ15N of N2 of natural gas as well as results of geochemical analyses of organic matter of the Ca2 source rock samples including Rock-Eval (RE) pyrolysis and elemental and stable C isotope compositions of kerogen. Four HP experiments conducted on two composite samples from Ca2 strata with different (II and III) prevailing genetic type of kerogen each, led to production of thermogenic gas which was used for geochemical comparison with natural gases accumulated within Ca2 strata. Hydrocarbon gases of analysed accumulations belong to two different genetic groups: (i) including gases sourced from sapropelic organic matter (type II kerogen) dispersed in the Ca2 strata produced during either both microbial and thermogenic processes or solely thermogenic processes and (ii) comprising gases not genetically related to the Ca2 source rock, originated from humic organic matter (type III kerogen) of high maturity from deeper buried strata. CO2 related to Ca2 strata primarily was produced during thermal decarboxylation of kerogen and carbonate dissolution by acid fluids, while CO2 unrelated to Ca2 strata was generated from thermal decomposition of deeper buried carbonate formations. H2S has been generated during thermal decomposition of sulphur-containing organic matter and thermochemical sulphate reduction (TSR) processes. The coexistence of CO2 and H2S indicates that these components might have been produced together by TSR and less microbial sulphate reduction (MSR) processes. Molecular nitrogen in analysed natural gases was generated mainly during thermal decomposition of organic matter, but atmosphere-derived molecular nitrogen is presumably also present.

Allura Red dye sorption onto electrospun zirconia nanofibers

Abstract Zirconia fibers were obtained by sol-gel and electrospinning techniques, using polyvinylpyrrolidone and zirconium butoxide as precursor. The as-spun fibers obtained from the precursor solutions were continuous and a mean diameter of 300 ± 95 nm was observed in samples obtained using a high precursor molar ratio (Z1: 0.1 M). The fibers were treated at different temperatures, and characterizations by thermal analysis, FTIR, Raman Spectroscopy and XRD demonstrated that monoclinic and tetragonal phases of zirconia are present. The predominant phase is monoclinic with some crystalline peaks corresponding to tetragonal zirconia. The phase transition from tetragonal to monoclinic zirconium oxide was observed at 1000 °C. At 1200 °C, the fiber morphology was preserved, while diameter decreased to 130 ± 39 nm due to the thermal decomposition of organic matter and sintering process. The adsorption behavior of the zirconia fibers was evaluated. Maximum adsorption capacity of Allura Red dye onto zirconia fibers was 0.895 mg/g. The data fitted better to pseudo-second order and Elovich kinetic models, while equilibrium data fitted to Freundlich and Temkin isotherms. The kinetic and equilibrium isotherm studies suggest that sorption of Allura Red dye on zirconia fibers takes place by a chemisorption process on a heterogeneous surface. The results showed that zirconia fibers can be used as an alternative adsorbent material for the effective removal of Allura Red dye from water. The manufacture of zirconia fibers by the electrospinning method offers an alternative to produce ceramics that can be used as adsorbent materials.

Disposal of waste-based fuels and raw materials in cement plants in Germany and Switzerland – What can be learned for global co-incineration practice and policy?

Abstract The limit value for emissions of total organic carbon (TOC) for incinerators in the European Union (EU) is 10 mg/m3. However, clinker burning is a material conversion process during which TOC emissions from the fuels occur concurrently with the thermal decomposition of organic material from the raw material mixture (limestone, marl, shale, etc.) in the preheater, which alone can emit more than 10 mg/m3. Therefore, the German legislature has created an exemption that allows authorities to set higher limit values for cement kilns if the cause of the higher emissions is the natural raw material mixture and not the co-incinerated waste. Separating the effects requires a test to determine the baseline emission of the natural raw material or waste raw material. Up until now, these tests were only used internally by companies. By applying such tests, the emissions from the fuels, particularly from waste-based fuels, can be determined, restricted and controlled. TOC emissions from natural materials cannot be avoided. In Switzerland and Germany these emissions are on average around 20–35 mg/m3. Switzerland has recently set a high TOC limit value of 80 mg/m3 for cement kilns, independent of the source of organic emissions, and even allows the use of polychlorinated biphenyl (PCB) contaminated soils as raw material (up to 10 mg/kg). This limit is too high and can result in unnecessary emissions of carcinogenic benzene, PCBs and other pollutants. Both the natural raw materials and waste raw materials emit organic carbon. However, there is one major difference. The natural raw materials emit mostly aliphatic compounds at temperatures up to about 600 °C, whereas the organic compounds originating from waste-based raw material components can include hazardous pollutants like polychlorinated biphenyls (PCBs) and other persistent organic pollutants (POPs), which desorb in the preheater and are released into the environment. Therefore, waste raw materials such as soils contaminated with POPs or other semivolatile toxic chemicals cannot be introduced via the raw mill -(leading to desorption in the preheater) but need to be fed in the kiln inlet. Cement kilns treating POPs or raw materials with problematic semivolatile organics need strict control and possibly continuous monitoring for dioxins and other POPs.

Using Field-Effect Gas Sensors for Monitoring H2 in Transformer Oil

Hydrogen can be released during the thermal decomposition of organic materials, therefore, monitoring its level in the working industrial high-voltage transformer oil allows you to identify the development of degenerative processes in advance, because these processes can lead to an accident in the future. In experiments has shown that highly sensitive and small-sized field effect gas sensor based on the metal-insulator-semiconductor structure can be used for measuring of Hydrogen in oil with direct contact of its structure with transformer oil. Given the harsh environmental conditions of hydrogen measurement the field effect capacity type gas sensor were fabricated by using laser micromilling technique for fabrication compact ceramic surface mounting device package and microheater for sustentation working temperature of metal-insulator-semiconductor structure.

Ketoconazole: compatibility with pharmaceutical excipients using DSC and TG techniques

Ketoconazole (KTZ) is an antifungal agent responsible for the inhibition of 14-α-demethylase sterol. The drug–excipient compatibility studies play an important role in pharmaceutical formulations development. Interactions between drug and excipients may affect the chemical nature, stability, bioavailability and consequently the therapeutic efficacy and safety profile. The main goal of this work was to evaluate the compatibility of KTZ with some excipients: corn starch, microcrystalline cellulose, colloidal silicon dioxide, lactose monohydrate and povidone, using differential scanning calorimetry and thermogravimetry (TG). Binary mixtures in a mass ratio of 1:1 between drug and excipient were used to make the study feasible. The comparison was performed using Tonset of the melt from pure drug and its enthalpy value (ΔHf) with respective values obtained for each binary mixture. Experimental and simulated TG/DTG curves were compared using the Pearson’s correlation coefficients to assess possible incompatibilities due to thermal decomposition of organic matter and/or gaseous products released. Thus, the excipients corn starch and colloidal silicon dioxide have been shown to be incompatible with KTZ.

Reduced fluids in porphyry copper-gold systems reflect the occurrence of the wall-rock thermogenic process: An example from the No.1 deposit in the Xiongcun district, Tibet, China

High fO2 conditions characterize the majority of global porphyry copper deposits and contain highly oxidized minerals, such as magnetite and anhydrite. In contrast, the No. 1 porphyry Cu–Au deposit in the Xiongcun district (Tibet, China) has abundant pyrrhotite, reduced fluids (CH4 ≫ CO2), and a relative lack of highly oxidized minerals, which are indicative of low fO2 conditions. Scanning electron microscopy, fluid inclusion, C–H–O–He–Ar isotopes, and whole-rock organic carbon contents and isotope analysis were used to constrain the evolution of ore-forming fluid, the origin of CH4 and metal deposition mechanisms for the No. 1 deposit. The He–Ar isotopic compositions (3He/4He = 0.11–0.96 Ra, 40Ar/36Ar = 418.7–2920.2) suggest that the ore-forming fluids predominantly derived from crust source with minor mantle input. The H–O isotopic analysis results (δ18OH2O = −1.8 to +5.2‰, δD = −106 to −89.9‰) indicate that the ore-forming fluids were derived from a magmatic source that mixed with some meteoric waters. The element compositions of zircons and fluid/melt inclusions from the mineralized Middle Jurassic quartz diorite porphyry reveal that the primary magma was characterized by high log fO2 (>NNO) conditions. The quartz diorite porphyry intruded into the carbon-bearing wall rocks produced abundant CH4 by thermal decomposition of organic matter (δ13CCH4 = −26.3 to −28.5‰), which changed the redox state of the porphyry copper system from oxidized to reduced condition. Ore elements were deposited via fluid boiling as a consequence of the rapid decrease in temperature and pressure.

The use of compiled thermal methods in the characteristics of source rocks on the example of menilite beds

The aim of the research was to compare the results of the thermal decomposition of organic matter using different research methods. Experiments were carried out to assess interpretation methods in the characterization of the generation potential of source rocks. The research was conducted for samples of Menilite shales, recognized on the basis of long-term geochemical studies as good quality source rocks. The samples represented the Menilite Beds of the Silesian Unit, taken from the outcrops in the Carpathians. Research using known methods: Rock-Eval pyrolysis (RE), thermogravimetric and calorimetric methods (TG/DSC), and pyrolysis methods combined with gas chromatography analysis (PY-GC), were performed on the same samples- both on rock samples, as well as isolated kerogen. Such integrated studies have so far not been conducted on any rock material. The applied research methods showed a significant comparability of the results obtained. A number of correlations were found between the parameters from individual methods, including: the amount of hydrocarbons separated during PY-GC in the temperature range of 300–650°C, and the parameter S2 from RE, and mass loss in the TG analysis in the same temperature range; S2 values of rock samples and kerogen with weight loss as a result of pyrolysis from TG/DSC analysis at temperatures in the range of 300–650°C; temperature values of the maximum peak S2 (Tpk2) of rock samples with the maximum mass loss temperature during TG analysis; residual carbon content (RC) from RE analysis of rock and kerogen samples with a mass loss as a result of burning residual organic matter from TG/DSC analysis at temperatures in the range of 650–1050°C. The mass loss determined during thermogravimetric analysis, combined with the percentage share of individual hydrocarbon fractions, in which the C9+ fraction is significant, confirms the high petroleum potential of the organic substance contained in the Menilite Beds. Comparative studies of pyrolytic methods: Rock Eval, TG/DSC and PY-GC have proved the compatibility of the results obtained with all methods. Each of the methods also makes it possible to obtain mutually complementary information relating to the TOC, the degree of thermal maturity and type of generated hydrocarbons and other non-hydrocarbon compounds. The conducted tests and performed correlations showed the usefulness of a set of thermal methods to obtain complete information on source rocks.

Influence of igneous intrusions on thermal maturity and optical texture: Comparison between a bituminous marl and a coal seam of the same maturity

The impact of a 120 cm thick dike on dispersed organic matter in the Triassic Marry Harbour (MH) bituminous marl in the Raanes Peninsula, Ellesmere Island, Arctic Canada, was studied using reflected light microscopy and Rock-Eval pyrolysis. Results were compared to a coal seam of similar maturity that was thermally altered by an igneous intrusion. The MH bituminous marl is mature and within the oil window (Ro = 0.94%), whereas the coal is high-volatile B bituminous rank (Ro = 0.80%). Thermal alteration impacted differently the organic-rich marl than the coal seam. Most of the heat generated by the intrusive emplacement in contact with coal is spent transforming coal to coke in the plastic layer/zone, similar to the process that coal undergoes in industrial coking operations. In contrast, the thermal alteration of sedimentary rocks occurs over longer distances as a result of the absence of a plastic layer/zone. The impact zone of the 120 cm thick igneous intrusion was greater in the MH bituminous marl, which became thermally altered (Ro = 2.34%) at 190 cm from the contact with the dike. On the contrary, the coal became thermally altered (%Ro = 5.0%) by a 240 cm alkali-basalt intrusion (twice the thickness of the MH dike) and its impact zone was only 65 cm. Heat and hot volatile matter produced by the thermal decomposition of organic matter and minerals (carbonate, dehydration of clay minerals) in contact with the igneous intrusion body is transferred through the sedimentary rock matrix by convection through fractures. This transformation is evident by the occurrence of the pyrolytic carbon at various distances in the fractured MH marl from contact. The hydrogen index (HI) shows a similar trend to that of the remaining source potential (S2). Both parameters decrease systematically toward the dike, and go through a minimum at 20 cm from the dike contact, as the indigenous organic matter is converted to hydrocarbons or devolatilized. At the dike contact, both S2 and HI have higher values. These trends are similar to those of the volatile elements H and Cl in the intruded coal seam. The free hydrocarbons (S1) showed a slightly different trend than S2 and HI. It increased initially from 300 cm and reached a maximum at about 190 cm from the dike contact before decreasing continually and reaching a minimum at 20 cm from the contact. At the dike contact, the S1 increased slightly, similar to the HI and S2. The presence of oil droplets trapped in carbonate concretions, in combination with the highest value of oil expelled from the source rock (based on S1/TOC) at distance of 190 cm from dike, is an indication of the influence of contact metamorphism on oil generation locally. Furthermore, it indicates that intrusion of igneous dikes into the bituminous MH marl resulted in an increase of organic matter maturation locally and in hydrocarbon generation.

Geochemical characteristics of natural gases related to Late Paleozoic coal measures in China

By 2013, more than 20 gas fields related to Late Paleozoic coal measures have been discovered in China, primarily distributed in the Bohai Bay, Ordos, Sichuan, and Junggar Basins. The total proven reserve in these gas fields is more than 3200 × 109 m3, accounting for 30.1% of the proven gas reserves in China. After analyzing the molecular compositions, stable carbon isotopes, and helium isotopes of 375 gas samples, genetic types and origins of the natural gas, as well as the secondary alterations it experienced, are discussed in this study. Most of the natural gas related to the Late Paleozoic coal measures are coal-type gas, with some of the gases from the Sichuan Basin and the Jingbian gas field in the Ordos Basin being oil-type gases generated from marine mudstones in the Permian Longtan Formation and marine carbonates in the Ordovician Majiagou Formation, respectively. The equivalent vitrinite reflectance values based on stable carbon isotopes of natural gases vary from 0.8% to 2.5%, indicating the mature to over mature stage. Positive carbon isotope series (δ13C-CH4 < δ13C-C2H6 < δ13C-C3H8) are observed in most gas samples, and carbon isotope reversals occur in the forms of δ13C-CH4 > δ13C-C2H6 and δ13C-CH4 < δ13C-C2H6 > δ13C-C3H8. The form of δ13C-CH4 > δ13C-C2H6 is primarily resulted from the mixing of oil-type gases of different maturities, while the form of δ13C-CH4 < δ13C-C2H6 > δ13C-C3H8 is primarily resulted from the mixing of coal-type gases of different maturities. High concentrations of hydrogen sulfide in natural gas from the Sichuan Basin and the Chenghai gas field in the Bohai Bay Basin are resulted from thermochemical sulfate reduction (TSR), which causes, to some extent, the fractionation of carbon isotopes. By contrast, the fractionation of methane carbon isotopes resulting from the TSR effect is not clear. Carbon dioxide from the Bohai Bay and Junggar Basins is primarily biogenic, generated via the thermal decomposition of organic matter, while that from the Ordos Basin, Sichuan Basin, and Chenghai gas field is generated via the thermal decomposition of carbonates. Carbon dioxide related to the TSR effect has also contributed to the Sichuan Basin and Chenghai gas field.

The origin and secondary alteration of dissolved gas in oil: A case study from the western Tu-Ha Basin, China

The Tu-Ha Basin is a typical Jurassic coal-derived petroliferous basin in western China. Seventeen natural gas samples were collected from the Jurassic Sanjianfang and Qiketai Formations, the Cretaceous Tugulu Formation, and the Paleogene Shanshan Formation to analyze the source and secondary alteration of natural gas. The natural gas samples were characterized by molecular and stable carbon (δ13C) and hydrogen (δD) isotope compositions. The results indicate that the natural gases are wet gases, in which methane is the main alkane component. Nitrogen (N2) and carbon dioxide (CO2) are the two non-hydrocarbons. The N2 values (>12%) are relatively higher, which increase rapidly at the burial depth of 1500–2000 m. Some natural gases have suffered secondary alteration at this depth. The natural gases are thermal genetic coal-derived gases (humic gas), coming from the Jurassic coal measure source rocks, which are chiefly in the low mature to early mature stage. Nitrogen in the shallow is chiefly derived from the atmosphere, while nitrogen at the deeper burial depth is mainly derived from the thermal decomposition of organic matter (OM). The shallow natural gas samples have the heaviest carbon isotope composition of ethane (δ13C2) and a carbon isotope sequence of (δ13C1 < δ13C2 > δ13C3 > δ13n-C4 < δ13i-C4), which is mainly caused by the biodegradation. The higher nitrogen content illustrates that a large amount of surface water is running into the reservoirs. Water washing occurs in the reservoirs, which decreases the molecular methane content and increases the amount of heavier hydrocarbons at 1500–2000 m depth.

Development of innovative low cost Biochar production technology

Biochar is a solid product of thermal decomposition of organic matter at a temperature below 900°C under conditions of oxygen deficit, produced for environmental or agricultural application. The selection of low cost biochar production technology will help to the resource poor farmers for application of such a wonderful soil amendments in their own field. In present study, an attempt has been made to develop an eco-friendly low cost biochar production technology which is very easy, economical and cost effective. Both the drum method (portable kiln) and pit method were very suitable for preparation of biochar and thus these two methods can be recommended to the farming community. The recovery of biochar was more in drum method as compared to pit method.

Ambient inclusion trails and microboring structures on Early Cambrian microfossils

Ambient inclusion trails (AITs) are microtubular structures on various substrates that have occurred widely through the geologic record. They are thought to be generated by the migration of inclusion grains (pyrite, magnetite, carbonaceous spherules), termed ″terminal propelled grains″, through a substrate driven by pressure solution from the in situ thermal decomposition of organic matter. AITs have been reported frequently from Archean rocks, and also commonly occurring with phosphatized fossils through late Neoproterozoic and Cambrian. During this timeframe, bioturbation was also becoming more intense, and some analogous, AIT-like structures may be more appropriately interpreted as endolithic micro-organisms or borings of predatory animals. It is thus crucial to reduce potential ambiguity between these types of structures, and provide keys for distinguishing AITs and real biogenic structures. From the Early Cambrian Kuanchuanpu Fm. in Xixiang, Southern Shaanxi, China, numerous microfossils hosting AITs were collected and examined, with recognition of two types of co-occurring micro-borings in addition to AITs. Type 1 micro-boring structures appear as long, unbranched, cylindrical filaments with isodiametric spheroidal expansions on the surface of steinkerns or moulds of small shelly fossils (SSFs); these structures correlate well with casts of known endolithic cyanobacterial fossils, Endoconchia lata . Type 2 micro-boring structures are comprised of dense networks of microborings and microtunnels on the phosphatized fossil materials, and are interpreted as trace fossils of endolithic fungi. Such a co-occurrence enables us to make direct comparisons between the variations in microtubular structures. We have made detailed observations of their morphological and taphonomic features, which collectively reveal that they are substantially different in both formation and mechanism of preservation. In the initial stage of formation of Type 1 structures, E. lata bored within the original calcite shells of SSFs, with the resulting borings preserved as phosphatic casts during phosphatization. Type 2 structures were caused by infestation of endolithic fungi on the phosphatized fossils while there were still much residual organic materials available for their probably heterotrophic life mode, leaving dense traces of boring behavior. With deeper burial and occurring later in the taphonomic sequence, thermal decomposition of the surrounding organic remains released gases that propelled small inclusions to move through the substrates, forming AIT tunnels. Some peculiar spherical grains preserved in the distal ends of AITs have been discovered and examined with Laser-Raman and EDS mapping. These data revealed that organic carbon is their major component. The intact spherical profiles without evidence of compression in their tunnel-facing backsides, and the perfect fit of the grain margins and AIT outlines suggest that these carbonaceous grains may have themselves been responsible for AIT formation rather than passive accumulation or secondary filling. Such rare carbonaceous terminal propelled grains of AITs not only explains the morphological diversity (rounded cross sections) of AIT tunnels, but also provide us with a new approach to investigate the taphonomic environment of the fossil-enriched strata. Raman geothermometry of these carbonaceous materials indicates that the Kuanchuanpu Fm. in this area underwent very low-grade metamorphism, with a peak metamorphic temperature estimated at 232–261°C. This implies that the fossils are mostly free from metamorphic overprints, and roughly constrains the upper limits of AIT formation. In general, as indirectly biogenic structures, the distribution of AITs is random and shows no preference for fossil taxonomy and no particular pattern. However, for those AITs that occurred on protoconodonts, there is an intriguing distribution pattern that AITs traveled around the outskirts of protoconodont spines, forming distinctive spiral grooves. Such a phenomenon may provide auxiliary evidence of their original composition by the following interpretations. The half-open grooves indicate the original composition of protoconodont spines were relatively soft material as opposed to hard bioapatite. The polygonal cross sections suggest, in this case, that the propelled grains were euhedral pyrite crystals, which were usually resulted by the decomposition of more recalcitrant organic materials. Our interpretation is that euhedral pyrite crystals moved from inside of the spines and were trapped by surrounding hard substrate, forming spiral grooves on the fossil-sediment interface. Our observations are consistent with the hypothesis that the original composition of the protoconodont spines are mainly organic, such as chitin, with secondary phosphatization—this hypothesis presents a more favorable scenario for the observed morphologies of the AITs formed by migration of euhedral pyrite crystals through a relatively soft substrate.