N2 Pressure Research Articles

Mechanism of water-induced alterations to nanoscale pores: Implications from anhydrous versus hydrous pyrolysis

In this study, shale samples from the Chang7 Member of Triassic Yanchang Formation in Ordos Basin, China were used to conduct artificially induced thermal maturity experiments from 250 °C to 450 °C for 72 h. The role of water in organic matter (OM) conversion and nanoscale porosity alterations were observed and discussed comprehensively by Rock-Eval pyrolysis, low pressure N2/CO2 adsorption, Fourier transform infrared spectroscopy (FTIR) and water-soluble organic acids (WSOAs) experiments. Results show that Rock-Eval pyrolysis parameters (Tmax, S1, and S2), TOC content, WSOAs and pore volume (PV) show slight changes below 350 °C while these parameters were considerably altered above 400 °C under two different pyrolysis conditions (anhydrous and hydrous), indicating that after 400 °C, the OM conversion and bitumen cracking will accelerate. In comparison to anhydrous pyrolysis, hydrous pyrolysis always has smaller Tmax, implying that water could inhibit OM thermal progression. Moreover, S1 of hydrous pyrolysis is approximately two times higher than that of anhydrous pyrolysis, which originates from water providing an exogenous source of hydrogen to generate excessive volumes of hydrocarbons, enhancing the conversion rate of OM. The WSOAs are 2 to 4 times greater under hydrous pyrolysis than anhydrous pyrolysis, denoting that the presence of water could improve the yield of organic acids via inhibiting the polycondensation of oxygen-containing functional groups and oxidizing organic components by hydroxyl radicals. Moreover, below 350 °C, pyrolysis shale residues exhibit a slightly smaller PV in hydrous pyrolysis, mainly due to the infilling effect of bitumen. However, exceeding 400 °C, PV that was obtained from low pressure N2 adsorption under hydrous pyrolysis conditions is found to be two times as large as the value under anhydrous pyrolysis conditions, which is attributed to the net-PV increase reactions such as thermal cracking, and the dissolution of organic acids. Furthermore, in anhydrous pyrolysis, the polycondensation of oxygen-containing functional groups and the carbon-carbon cross linking could be considered as the two main reaction pathways to release the sources of hydrogen. Collectively, the presence of water is significant for hydrocarbon generation and porosity evolution during thermal progression of OM at various stages.

Highly selective catalytic transfer hydrogenation of biomass derived furfural to furfural alcohol over Zr/SBA-15 catalysts

The effective utilization of furfural (FU) from biomass for the production of furfuryl alcohol (FOL) is becoming increasingly important due to the versatility of FOL production of valuable chemicals. This study reports a highly efficient approach for in-situ hydrothermal methods to prepare SBA-15 (SB) and x% Zr/SBA-15 (ZSB) composite catalysts with different weight percentages (x = 1, 3, and 5 wt.%). The prepared bare and most active catalysts were analyzed by XRD, FT-IR, FE-SEM, EDS, and TEM. Characterization studies showed that Zr species were present and uniformly distributed in the SB framework. All the prepared materials were used for liquid phase catalytic transfer hydrogenation (CTH) of FU with isopropanol (2-PrOH) at atmospheric N2 pressure (1 atm) under mild reaction conditions. The 3ZSB catalyst showed excellent conversion of FU (100 %) and remarkably high selectivity for FOL (97 %). To achieve the highest possible conversion of FU with high selectivity to the desired products, the experimental parameters such as reaction temperature, hydrogen donor, time, molar ratio, and catalyst weight were optimized. The reusability of the most active 3ZSB composite catalysts was also tested for up to six sequences. Moreover, no significant change in catalytic performance was observed. In this study, a green, efficient, and sustainable process for the catalytic synthesis of FOL using biomass-derived FU is presented. This process is of great importance in promoting the sustainable use of biomass resources.

Molecular Dynamics Simulation of CH4 Displacement through Different Sequential Injections of CO2/N2

As a clean energy source, coalbed methane (CBM) produces almost no exhaust gas after combustion, and its extraction and efficient utilization play a key role in supporting sustainable development. Therefore, molecular dynamics simulations were used to research the diffusion of CH4 in coal after injecting CO2/N2 in different sequences and to clarify the efficiency of CBM extraction under different injection sequences, so as to contribute to sustainable development. The results show that the adsorption amounts of CO2 and N2 in different injection sequences are obviously different. To narrow the gap between the two injection amounts, the injection pressure of N2 can be appropriately increased and that of CO2 can be reduced, or N2 can be injected preferentially instead of CO2. When CO2 is injected first, the interaction energy between CH4 and coal is stronger and increases slightly with displacement time as a whole. The interaction energy curve of the N2 injection decreases, and the displacement effect becomes worse and worse. From the diffusion and relative concentration distribution of CH4, it can be seen that the diffusion of CH4 molecules outside the grain cell is more obvious when N2 is injected first. In terms of the number of CH4 molecules diffusing outside the crystal cell, it is less when CO2 is injected first than when N2 is injected first. The average value of the velocity distribution of CH4 increases slightly when CO2 is injected first and decreases significantly when N2 is injected first, but the average value is overall higher for N2 injection first. From the difference in diffusion coefficients before and after the gas injection, it can be seen that the decrease in permeability due to the expansion of the coal matrix by CO2 is more obvious than the increase in permeability due to the contraction of the coal matrix by N2.

Diazotrophic nitrogen fixation through aerial roots occurs in Avicennia marina: implications for adaptation of mangrove plant growth to low-nitrogen tidal flats.

Nitrogen limitation of primary production is common in coastal ecosystems. Mangrove trees maintain high levels of nitrogen fixation around their roots. The interior aerial space of mangrove roots, in which atmospheric gas is supplied through lenticels, could be efficient sites for nitrogen fixation. We measured tidal variations of partial pressure of N2 in root aerenchyma and conducted field experiments using 15 N2 as a tracer to track N2 movement through aerial roots of Avicennia marina. We used the acetylene reduction assay to identify the root parts harboring diazotrophs. The nitrogenase activity and estimated nitrogen fixation through aerenchyma were higher in pneumatophores and absorbing roots than in cable roots. Positive correlations between root nitrogen contents and turnover rates of root nitrogen derived from N2 through aerenchyma suggested that the internal supply of N2 to diazotrophs could be the main source for nitrogen assimilation by A. marina roots. Our results confirmed that N2 is supplied to diazotrophs through aerial roots and that nitrogen fixation occurs in A. marina roots. The aerial root structures, which occur across families of mangrove plants, could be an adaptation to survival in not only low-oxygen environments but also tidal flats with little plant-available nitrogen.

Impact of sputtering gas on the microstructural, mechanical and wetting properties of vanadium nitride coatings

Vanadium nitride (VN) coatings were deposited via reactive DC magnetron sputtering technique on a hot substrate (400 °C) with varying partial pressure of N2. The impact of nitrogen partial pressure on the crystal structure, microstructure, elemental composition, surface topography, mechanical and wetting properties of VN coatings was investigated using grazing incidence X-ray diffraction (GIXRD), Raman spectroscopy, field emission scanning electron microscope (FESEM), energy dispersive spectroscopy (EDS), atomic force microscope (AFM), nano-indentation, and drop shape analyzer (DSA). The variation in the N2 partial pressure leads the significant changes in the microstructure, mechanical and wetting properties of the coatings. The GIXRD spectra reveals the formation of crystalline FCC phase in the deposited VN coatings. However, at 100% N2 partial pressure, the preferred orientation of crystal planes changes from (200) to (220). The FESEM image reveals that at low N2 partial pressure, the coating exhibits well-separated grains with clearly visible grain boundaries. As the N2 partial pressure increases, the agglomeration of grains becomes more pronounced, and the grain boundaries become less discernible. However, at 100% N2 partial pressure, the structure transforms into triangular nanoflake-like prismatic structures with voids. The VN coatings with 60% N2 partial pressure exhibits the highest mechanical properties whereas at 100% N2 partial pressure, the VN coatings reveal super-hydrophilic character.

Early Nitrogen Budget of the Martian Atmosphere and Its Evolution

AbstractIn 1976, Viking measured a 14N/15N ratio of 170 ± 15 in the Martian atmosphere, and in 2012, MSL measured a ratio of 173 ± 11. This type of enrichment of the heavier isotope can only be explained by a significant loss of N to space, with the lighter isotope escaping more efficiently. A quantitative understanding of this nitrogen evolution of the Martian atmosphere requires analyzing all of the sources, sinks and exchanges of N2. We employ the processes of sputtering, photochemical escape by dissociative recombination and photodissociation, volcanic outgassing and impact processes to understand the evolution of N2 through time. We use a forward time‐marching model starting at initial abundance at 4 Gya to calculate the N2 abundance and 15N/14N enrichment over the history of Mars. We also incorporate a simultaneous CO2 evolution, which decays in either a power‐law or linear function to the present‐day value of 6 mbar. We constrain the simulated evolutionary tracks to the present day N2 abundance and 15N/14N ratio of the Martian atmosphere to explore the initial conditions of the early atmosphere. Our model indicates a modal value of 120 mbar of initial N2 pressure, with an upper limit of 3.6 bars, for an initial CO2 pressure of 1 bar. This modal value is in good agreement with the N2 budget of Earth's atmosphere when scaled to the mass of Mars, which amounts to ∼110 mbar.

High Thermal Conductivity of Submicrometer Aluminum Nitride Thin Films Sputter-Deposited at Low Temperature.

Aluminum nitride (AlN) is one of the few electrically insulating materials with excellent thermal conductivity, but high-quality films typically require exceedingly hot deposition temperatures (>1000 °C). For thermal management applications in dense or high-power integrated circuits, it is important to deposit heat spreaders at low temperatures (<500 °C), without affecting the underlying electronics. Here, we demonstrate 100 nm to 1.7 μm thick AlN films achieved by low-temperature (<100 °C) sputtering, correlating their thermal properties with their grain size and interfacial quality, which we analyze by X-ray diffraction, transmission X-ray microscopy, as well as Raman and Auger spectroscopy. Controlling the deposition conditions through the partial pressure of reactive N2, we achieve an ∼3× variation in thermal conductivity (∼36-104 W m-1 K-1) of ∼600 nm films, with the upper range representing one of the highest values for such film thicknesses at room temperature, especially at deposition temperatures below 100 °C. Defect densities are also estimated from the thermal conductivity measurements, providing insight into the thermal engineering of AlN that can be optimized for application-specific heat spreading or thermal confinement.

Significance of particle size and lithotype on adsorption equilibrium in low pressure N2 and CO2 adsorption of coal: Implications for abnormal phenomenon of adsorption in N2 adsorption of semianthracite

Low pressure N2 and CO2 adsorption was conducted on different lithotypes (vitrain and clarain) with ten different particle sizes ranging from 2.8-2.0 mm to 0.045–0.020 mm of semianthracite (Ro, max = 2.06%) having the abnormal phenomenon of adsorption in N2 adsorption. The effects of particle size and lithotype on adsorption equilibrium in N2/CO2 adsorption and associated pore structure were systematically analyzed to explore the possible reason for the abnormal phenomenon of adsorption and propose the suitable particle size for N2/CO2 adsorption. Decreasing particle size in vitrain and clarain shortens the gas flow paths and removes the constrictions, which facilitates the complete adsorption equilibrium in CO2 adsorption and improves the degree of adsorption equilibrium in N2 adsorption. For different lithotypes with the same particle size, clarain achieves complete adsorption equilibrium easier and quicker in CO2 adsorption and has higher degree of adsorption equilibrium in N2 adsorption than vitrain. The abnormal phenomenon of adsorption in N2 adsorption is resulted from the combined effect of extremely low degree of adsorption equilibrium and elastic deformation of coal. The abnormal phenomenon of adsorption is more pronounced in vitrain than in clarain and gradually disappears with decreasing particle size in both vitrain and clarain. Particle sizes of <0.075 mm (>200 mesh) and <1.0 mm (>18 mesh) are recommended as the suitable particle sizes in N2 adsorption and CO2 adsorption to accurately characterize pore structure for the coals having the abnormal phenomenon of adsorption, respectively.

Fully Printed HTL-Free MAPbI3 Perovskite Solar Cells with Carbon Electrodes

This study investigates fully printed methylamine vapour-treated methylammonium lead iodide (MAPbI3) hole transport layer (HTL)-free perovskite solar cells (PSCs) with a carbon electrode. We describe a method that can be used to deposit MAPbI3 films in an ambient environment with doctor blading that is entirely free of spin coating and has precise morphology control, in which the varying input N2 pressure affects the film morphology. Consequently, a fully printed perovskite solar cell with an ITO/SnO2/MAPbI3/carbon structure was fabricated using a doctor-blading SnO2 electron transport layer and a screen-printed carbon counter electrode. The low-temperature-derived PSCs exhibited a superior power conversion efficiency (PCE) of 14.17% with an open-circuit voltage (Voc) of 1.02 V on a small-active-area device and the highest efficiency of &gt;8% for an illumination exposure area of 1.0 cm2, with high reproducibility. This work highlights the potential of doctor blading and methylamine vapour treatment as promising methods for fabricating high-performance perovskite solar cells. A doctor-blading approach offers a wide processing window for versatile high-performance perovskite optoelectronics in the context of large-scale production.

Dynamics of a laser plume plasma in an atmosphere of the He, Xe, Ar, and N2 buffer gases during ablation of a SiMn target

Investigations of the dependence of the ferromagnetism of MnxSi1-x (x ∼ 0.5) films on the energy spectrum of target plume particles are topical for spintronics. The time-of-flight (TOF) method using a Langmuir probe has been used to study the dynamics of a laser plume during ablation of a SiMn target in vacuum and in an atmosphere of He, Xe, Ar, N2 buffer gases in a wide pressure range from 10−6 to 4∙10−1 mbar. The TOF curves of the probe signal have been obtained by ablation of the SiMn target by the second harmonic of the Q-switched Nd:YAG laser. A nonmonotonic dependence of the probe signal amplitude on the buffer gas pressure was established. A feature of the delay of the TOF curve signal from the moment of target ablation as a function of the N2 pressure in the chamber was revealed, which was explained by the resonant scattering of the Si + ion and the N2 nitrogen molecule. The most suitable gases for control of the ion velocity were selected based on the dynamics of the laser plume. The dependence of the electrical characteristics of MnxSi1-x (x ∼ 0.5) films on the pressure of helium and argon has been established.

Unraveling Exclusive In-Plasma Initiated Oxidation Processes Occurring at Polymeric Surfaces upon O2 Admixtures to Medium Pressure Ar and N2 DBD Treatments.

Polymeric surfaces have been increasingly plasma-activated to adopt adequate chemistries, enabling their use in different applications. An unavoidable surface oxygen insertion upon exposure to non-oxygen-containing plasmas was always observed and mainly attributed to in-plasma oxidation stemming from O2 impurities in plasma reactors. Therefore, this work investigates exclusive in-plasma oxidation processes occurring on polyethylene surfaces by purposely admixing different O2 concentrations to medium-pressure Ar and N2 dielectric barrier discharges (base pressure: 10-7 kPa). Hence, distinctive optical emission spectroscopy and in-situ X-ray photoelectron spectroscopy (XPS) data were carefully correlated. Pure N2 discharge triggered an unprecedented surface incorporation of large nitrogen (29%) and low oxygen (3%) amounts. A steep rise in the O-content (10%) at the expense of nitrogen (15%) was detected upon the addition of 6.2 × 10-3% of O2 to the feed gas. When the added O2 exceeded 1%, the N content was completely quenched. Around 8% of surface oxygen was detected in Ar plasma due to high-energy Ar metastables creating more surface radicals that reacted with O2 impurities. When adding only 6.2 × 10-3% of O2 to Ar, the surface O content considerably increased to 12%. Overall, in-plasma oxidation caused by O2 impurities can strikingly change the surface chemistry of N2 and Ar plasma-treated polymers.

Revealing roles of CO2 and N2 in pressurized hydrothermal carbonization process for enhancing energy recovery and carbon sequestration

In this study, CO2– and N2-pressurized hydrothermal carbonization processes were investigated to understand the catalytic effects of CO2 on hydrochar production and its quality (e.g., surface properties, energy recovery, and combustion behaviour). Both CO2– and N2-pressurized HTC processes could enhance the energy recovery (from 61.5% to 63.0–67.8%) in hydrochar by enhancing the dehydration reactions. Nonetheless, the two systems exhibited contrasting trends in volatile release, oxygen removal, and combustion performance as a function of increasing pressure. High N2 pressure enhanced deoxygenation reaction, facilitating the release of volatiles and increasing the hydrochar aromaticity and combustion activation energy (172.7 kJ/mol for HC/5N). Without the contribution of CO2, excessively high pressure may cause an adverse impact on the fuel performance owing to higher oxidation resistance. This study presents an important and feasible strategy to utilise CO2-rich flue gas in the HTC process to produce high-quality hydrochar for renewable energy and carbon recovery.

Experimental study on enhanced coal seam gas extraction by uniform pressure/pulse pressure N2 injection

Gas extraction is the fundamental way to prevent and control gas as well as to obtain clean energy. Based on the analysis of the mechanism of conventional negative-pressure gas extraction technology and N2 injection enhanced gas extraction technology, the technology of pulse pressure N2 injection enhanced gas extraction is proposed. The experiments of CH4 displacement by uniform pressure/pulse pressure N2 injection are carried out. The migration pattern of gas components during the whole process of CH4 displacement by N2 injection is quantitatively characterized. The influence pattern and sensitivity of N2 injection pressure on the effect of CH4 displacement are analyzed. The economic benefits of N2 injection by uniform pressure/pulse pressure to displace CH4 are investigated. The results indicate that conventional negative-pressure gas extraction technology has disadvantages such as insufficient seepage power and gas extraction will soon enter the exhaustion stage. While N2 injection enhanced gas extraction technology not only has the flow increasing effect of gas itself factors but also has the flow increasing effect of injected energy for changing coal properties. During the process of displacing CH4 by uniform pressure/pulse pressure N2 injection, the CH4 volume fraction decreases and the N2 volume fraction increases as the N2 injection pressure increases. Increasing the injection pressure of two N2 injection methods can effectively shorten the T50% (the time when the CH4 volume fraction is equal to the N2 volume fraction is equal to 50%), but with a reduced degree of impact. Increasing injection pressure not only increases the amount of CH4 precipitation but also increases the amount of N2 precipitation, which is not conducive to the later utilization of the precipitated CH4. With the increase of N2 injection pressure, the sensitivity of CH4 displacement efficiency by uniform pressure N2 injection decreases, the sensitivity of CH4 displacement efficiency by pulse pressure N2 injection remains the same, and the sensitivity of CH4 displacement ratio by uniform pressure/pulse pressure N2 injection decreases. The CH4 prevent and control effect, N2 injection cost, and CH4 resource utilization of pulse pressure N2 injection are better than that of uniform pressure N2 injection. The technology of enhanced gas extraction by pulse pressure N2 injection not only improves the CH4 prevent and control effect but also reduces N2 injection cost. At the same time, it promotes the efficient utilization of CH4 resources. The research results have great significance and value for improving the level of gas disaster prevention and resource development.

A new approach to turbostratic carbon production via thermal salt-assisted treatment of graphite

Here graphite was found to undergo carbon/carbonate gasification at 800 °C, resulting in exfoliation of graphite to form turbostratic carbon. The lattice distance of graphene sheets in graphite are shown to undergo marked changes following treatment with molten ternary eutectic carbonate (Li2CO3: 43.5%, Na2CO3: 31.5%, K2CO3: 25%) during slow temperature ramping rates (5 °C/min) under N2 at temperatures above 750 °C. Initial findings suggest that approximately 50 wt% of graphite experiences interlayer expansion. The conventional d spacing of 0.34 nm is modified to a range of intervals between 0.41 nm and 1.22 nm. As a consequence of high operational temperature (800 °C), cations (Li+, Na+ and K+) as well as potentially the anion (CO32–) intercalate between graphitic layers and overcome Van der Waal force between layers. Employing a pressurized N2 environment of 5 bar and 10 bar successfully controls carbonate vaporization and decomposition, as well as inducing ordered layer manipulation to exfoliate more graphite planes from the edges towards deeper levels of the particles. Exploring parameters of both carbonate loading and treatment time in addition to pressure demonstrate that this work opens up a rich selection of parameters that can be used to produce carbons with tuned properties from graphite.

Structural design and strength analysis of the calorimeter pipeline joint for the negative neutral beam injection system of China fusion engineering test reactor

The negative ion-based neutral beam injection (NNBI) verification prototype system is one of the core components of China Fusion Engineering Test Reactor (CFETR). To effectively cut off the beam and debug the neutral beam device, the power measurement system plays an indispensable role. In this study, we examine the detailed design of the pipeline joint structure of the calorimeter verification prototype, focusing on the impact of the structural design of the target panel pipeline joint on the structural strength and manufacturing process required by the cooling circular pipeline joint of the calorimeter. Based on this, the manufacturing process and strength of the integrated pipeline structure of the target panel are inspected under a design pressure of 4 MPa, including theoretical analysis of the integrated pipeline pressure-bearing structural design, welding technology design, and finite element simulation under high pressure. Accordingly, the feasibility of the final manufacturing scheme and key technologies are analyzed. The pressure test of the sample under an internal N2 pressure of 4 MPa verifies that its structure can meet the design requirements, thereby providing reference for the effective structural design and manufacturing of the NNBI calorimeter prototype.

Optimizing 129Xe and 131Xe relaxation in an NMR gyroscope using buffer gas pressure and wall coating

The accuracy of inertial measurement performed by the nuclear magnetic resonance gyroscope (NMRG) with two isotopes depends on the duration of transverse relaxation. Extending the relaxation of the xenon isotopes at the same time plays a very important role in the accuracy of gyro. The relaxation time of 129Xe and 131Xe can be increased to about 15–20 s by optimizing the buffer gas pressure of N2 at about 0.57 amg and coating RbH, respectively. According to the results of theoretical analysis and experimentation, the gyro stability reaches 0.6°/h, and the active measurement volume is 3 × 3 × 3 ∼ mm3.

Liquid-Phase Dehydration of Glycerol to Acrolein with ZSM-5-Based Catalysts in the Presence of a Dispersing Agent.

Liquid-phase dehydration of glycerol to acrolein was investigated with solid acid catalysts, including H-ZSM-5, H3PO4-modified H-ZSM-5, H3PW12O40·14H2O and Cs2.5H0.5PW12O40, in the presence of sulfolane ((CH2)4SO2) as a dispersing agent under atmospheric pressure N2 in a batch reactor. High weak-acidity H-ZSM-5, high temperatures and high-boiling-point sulfolane improved the activity and selectivity for the production of acrolein through suppressing the formation of polymers and coke and promoting the diffusion of glycerol and products. Brønsted acid sites were soundly demonstrated to be responsible for dehydration of glycerol to acrolein by infrared spectroscopy of pyridine adsorption. Brønsted weak acid sites favored the selectivity to acrolein. Combined catalytic and temperature-programmed desorption of ammonia studies revealed that the selectivity to acrolein increased as the weak-acidity increased over the ZSM-5-based catalysts. The ZSM-5-based catalysts produced a higher selectivity to acrolein, while the heteropolyacids resulted in a higher selectivity to polymers and coke.

Photoelectrochemical N2 -to-NH3 Fixation with High Efficiency and Rates via Optimized Si-Based System at Positive Potential versus Li0/.

As a widely used commodity chemical, ammonia is critical for producing nitrogen-containing fertilizers and serving as the promising zero-carbon energy carrier. Photoelectrochemical nitrogen reduction reaction (PEC NRR) can provide a solar-powered green and sustainable route for synthesis of ammonia (NH3 ). Herein, we report an optimum PEC system with a Si-based hierarchically-structured PdCu/TiO2 /Si photocathode and well-thought-out trifluoroethanol as the proton source for lithium-mediated PEC NRR, achieving a record high NH3 yield of 43.09μg cm-2 h-1 and an excellent faradaic efficiency of 46.15% under 0.12-MPa O2 and 3.88-MPa N2 at 0.07V versus lithium(0/+) redox couple (versus Li0/+ ). PEC measurements coupled with operando characterization revealed that the PdCu/TiO2 /Si photocathode under N2 pressures facilitate the reduction of N2 to form lithium nitride (Li3 N), which reacts with active protons to produce NH3 while releasing the Li+ to reinitiate the cycle of the PEC NRR. The Li-mediated PEC NRR process is further enhanced by introducing small amount of O2 or CO2 under pressure by accelerating the decomposition of Li3 N. For the first time, this work provides mechanistic understanding of the lithium-mediated PEC NRR process and opens new avenues for efficient solar-powered green conversion of N2 -to-NH3 . This article is protected by copyright. All rights reserved.

Catalytic hydrothermal deoxygenation of sugarcane bagasse for energy dense bio-oil and aqueous fraction acidogenesis for biohydrogen production

The study focuses on the effective conversion of sugarcane bagasse (SCB) by catalytic deoxygenation using various alkali and metal-based catalysts under N2 pressure employing water as solvent. The specific influence of catalyst over bio-crude yields (bio-oil and aqueous fraction) including energy recovery ratio was explored. The optimum catalytic condition (Ru/C) resulted in ∼ 70% of bio-crude and 28% of bio-oil with an improved HHV (31.6 MJ/kg) having 11.6% of aliphatic/aromatic hydrocarbons (C10–C20) which can be further upgraded to drop-in fuels. The biocrude composed of 44% of aqueous soluble organic fraction (HTL-AF). Further, the carbon-rich HTL-AF was valorized through acidogenic fermentation to yield biohydrogen (Bio-H2). The maximum bio-H2 production of 201 mL/g of TOC conversion (K2CO3 catalyst) was observed with 7.7 g/L of VFA. The SCB was valorized in a biorefinery design with the production of fuels and chemical intermediates in a circular chemistry approach.

Shallow burial shale gas accumulation pattern of the Wufeng–Longmaxi Formations in the northern Guizhou area, western Yangtze platform

Although continuous breakthroughs of economic shale gas exploitation have been made globally within the middle–deep buried depth (∼1500–3500 m), the shallow–buried (less than 1500 m) shales are also widely distributed, showing excellent exploration prospects. However, the shale gas accumulation (SGA) pattern of the shallow burial shale remains unknown, limiting future shale gas exploration. To investigate the SGA pattern and the exploration potential of shale gas in shallow–buried shales, experiments such as X–Ray Diffractometer, N2 and CO2 adsorption, Focused Ion Beam Scanning Electron Microscopy (FIB-SEM), total organic carbon (TOC) content, gas chromatography–mass spectrometry, and field gas content test were carried out based on three wells penetrated the Wufeng–Longmaxi Formation with the buried depths of less than 700 m in the Northern Guizhou area, western Yangtze Platform. The geochemical and mineral records indicate that the organic matter is enriched as a result of global climate and regional tectonic activity, indicating the sufficient gas generation potential. The results of low pressure N2 and CO2 adsorption, as well as images of the FIB–SEM show that the mesopores are controlled by the organic matter, and the micropores, which are associated with minerals (primarily clays), can provide much more specific surface area and pore space in shallow–buried shales. Furthermore, carbonates with low porosity and permeability from the Songkan, Jiancaogou and Baota Formations, and the shale interval with low TOC values, weak brittleness, and low porosity, can serve as good roofs and floors for the SGA. Despite the fact that multi–stage tectonic movements resulted in the formation of faults and fractures, the good preservation, adequate gas storage space, and sufficient hydrocarbon generation potential contribute to the SGA in the shallow–buried shale.