Increasing Pyrolysis Temperature Research Articles

Understanding cellulose pyrolysis under hydrogen atmosphere

The product distributions of cellulose pyrolysis under different pressures, temperatures, and atmospheres were investigated using a high-pressure micropyrolyzer to clarify the pyrolysis reaction mechanism of cellulose decomposition with hydrogen. EGA-MS results shows that the increase in hydrogen pressure prolonged the second stage of cellulose pyrolysis, which was dominated by decarboxylation. Pyrolysis products of cellulose under helium mainly included levoglucosan, furfural, and acids, while cellulose hydropyrolysis mainly produced C5-C7 ketones, besides small amount of alcohols, aromatics and aliphatic hydrocarbons, and even small amount of phenolics. Carbon yield of ketones was as high as 27.2% from cellulose hydropyrolysis under 2.5 MPa hydrogen and 500 °C. The yield of liquid products and non–condensable hydrocarbons increased with elevated hydrogen pressure. The formation mechanisms of aromatics, phenolics, aliphatic hydrocarbons, aldehydes, ketones, and alcohols under hydrogen atmosphere were discussed. Acetaldehyde was produced by acids through a HDO reaction. C5-C7 chain ketones and cyclic ketones were generated by furfural through HDO and hydrocracking reactions. The Diels–Alder reaction to generate aromatics was enhanced by increasing pyrolysis temperature under hydrogen atmosphere. The reaction network of cellulose hydropyrolysis was also proposed.

Aging features of metal(loid)s in biochar-amended soil: Effects of biochar type and aging method

Soil contamination with toxic metals and metalloids has become a major threat to global food security. Among various immobilization agents that can stabilize toxic metal(loid)s effectively, biochar is promising due to its ability to restore soil health. Yet the aging characteristics of biochar following its amendment in soil remain poorly explored. Therefore, this study used standard biochars to depict their aging effects on remediation of metal(loid)-contaminated soil. A total of 2304 observations were made, including 6 biochar feedstocks (rice husk, soft wood, oilseed rape straw, miscanthus straw, sewage sludge and wheat straw), 2 pyrolysis temperatures (550 °C, 700 °C), 8 metal(loid)s (Mn, Ni, Cu, Zn, As, Cd, Sb, Pb), 4 aging methods (natural aging, freeze-thaw cycling, wet-dry cycling, chemical oxidation with H2O2), and 6 sampling intervals. Sewage sludge biochars exhibited the highest resistance to both artificial and natural aging, which may be related to the abundant oxygen-containing functional groups that favor metal complexation, and poorly-developed pore structures that limit the access of natural aging forces. A distinct relationship between ash and temperature was observed, where for high-ash biochars, an increase in pyrolysis temperature indicated lower resistance to aging, while for low-ash biochars, elevated pyrolysis temperature led to higher resistance. The aging behaviors of Cu and Sb were quite similar, which were both highly susceptible to chemical oxidation-induced dissolved organic carbon (DOC) release. Wet-dry cycling and freeze-thaw cycling revealed aging patterns that were similar to those of naturally aged soils as confirmed by cluster analysis. Lab aging data were then compared with existing biochar field aging results. Contrasting long-term immobilization performances were found in different studies, which were attributed to various causes associated with both biochar property and climate. The results of this study provide fresh insights into the long-term risks in the management of metal(loid)-contaminated agricultural soils.

Characteristics and chlorine reactivity of biochar-derived dissolved organic matter: Effects of feedstock type and pyrolysis temperature

Increasing biochar application worldwide may release more biochar-derived dissolved organic matter (BDOM) to the source water for drinking water supply. However, it is unclear how feedstock types and pyrolysis temperatures for biochar production would affect the characteristics and chlorine reactivity of BDOM. Here, we studied the spectroscopic characteristics of BDOM pyrolyzed from pine needle, wheat straw, walnut shells, alfalfa, pig manure, and sludge derived biochars at 300, 500, and 700 °C, as well as the formation potential of disinfection byproducts (DBPs) and their bulk toxicity after BDOM chlorination. The N/C ratio of biochar was higher for N-rich than C-rich feedstocks. Optical analyses indicated that BDOM aromaticity was highest at 700 °C, while the impact of pyrolysis temperature on the molecular weight of BDOM varied greatly among feedstocks. Increasing pyrolysis temperature caused consistently decreased BDOM reactivity toward haloketone formation but did not show consistent impacts on the other DBPs. Among feedstocks, the N-rich sludge showed the highest specific haloacetonitrile formation potential of BDOM at any given pyrolysis temperature. The DBP formation potential from biochar was consistently highest at 300 °C and was higher for N-rich than C-rich feedstocks. The microtoxicity of DBP mixture was highest for the BDOM derived from sludge produced at 300 °C. This study highlights the high variations in characteristics and chlorination reactivity of BDOM with varying feedstocks and pyrolysis temperatures, which implies that more attention should be paid to the environmental impacts of the intensive application of low-temperature biochar from N-rich feedstock such as sludge.

Engineering Lignin-Derived Carbon–Silicon Nanocomposite Electrodes: Insight into the Copyrolysis Mechanism and Process–Structure–Property–Performance Relationships

As a renewable source, available in a large quantity, it is rewarding to find applications for lignin with high added value. We report the use of lignin in synthesizing a three-dimensional, interconnected carbon/silicon nanoparticle (C/Si NP) composite material as a low-cost replacement to conventional anode materials synthesized using expensive and toxic solvents and binders such as polyvinylidene in today’s lithium-ion battery (LIB) manufacturing process. To understand how lignin pyrolysis chemistry and processing conditions affect the structure, mechanical property, and electrochemical performance of the synthesized electrode materials, the thermochemical conversion process was, for the first time, quantitatively investigated using analytical pyrolysis–gas chromatography–mass spectrometry (GC–MS) along with a suite of other analytical tools. Results suggest that the surface bonding interaction of the C/Si NPs was evolved from pristine Si to −Si–O–C–, to −O═Si═O–, with the increase of pyrolysis temperature. The −Si–O–C– bond plays a key role in enhancing the cohesive strength and thus improving the electrochemical performance of the Si composite electrode. The pyrolysis–GC–MS can serve as a useful tool to predict the optimal pyrolysis temperature or tailor the properties of the synthesized composite electrodes by controlling the pyrolysis conditions. This study elucidates the processing–structure–property–performance relationships among lignin pyrolysis chemistry, carbon material structure and properties, and the electrochemical performance of the resulting electrode materials. Such knowledge serves as a basis for designing lignin-derived composite materials for electrochemical energy storage applications.

Retracted] Experiment and Algorithm Research of Coal Direct Liquefaction Residual Oil Pyrolysis and Coking Technology Based on Lumped Kinetic Engineering

With the development of computer operation technology and algorithms, the lumped dynamic model is more practical, and the development and application are more comprehensive. Among them, the direct coal liquefaction residual oil pyrolysis and coking technology, as a coal‐to‐liquid process, can increase the oil yield of the coal liquefaction process and reduce environmental pollution. The purpose of this paper is to study the experiment and algorithm of coal direct liquefaction residual oil pyrolysis and coking technology based on lumped kinetic engineering. Starting from the lumped kinetic engineering, this paper takes the direct coal liquefaction residual oil pyrolysis and coking technology as the research object. Based on the experiment of small‐ and medium‐sized equipment, the residual oil pyrolysis and coking experiment is carried out. This paper further analyzes the components of the experimental products and explores the factors that affect the yield of residual pyrolysis oil based on the five lumped kinetic model of coking. Experimental data shows that when the pyrolysis temperature is 450°C, the content of liquefied heavy oil HS in the pyrolysis oil is 47.87%, the content of asphaltene A is 44.28%, and the content of preasphaltene PA is 7.85%; the pyrolysis temperature is 500 °C. At this time, the content of liquefied heavy oil HS in the pyrolysis oil is 54.97%, the content of asphaltene A is 40.23%, and the content of preasphaltene PA is 4.8%. It can be seen that, with the increase of pyrolysis temperature, the content of liquefied heavy oil HS increases, and the content of asphaltene A and preasphaltene PA decreases.

Interaction of Lead and Calcium with Biochar Produced from Cassava Waste: Perspectives for Agricultural and Environmental Application

The biochar from slow pyrolysis under controlled conditions is favorable in the transformation of waste into materials that serve as soil conditioners, and/or environmental remediation. Thus, this work aimed to produce and characterize biochar from cassava waste under different temperature conditions and evaluate interactions with Ca2+ and Pb2+ for agricultural and environmental applications. To investigate the efficiency of the interaction of biochar with nutrients (Ca) and contaminants (Pb), the influence of pH and contact time were evaluated. There was an increase in pH, pHzpc (zero point charge), and condensed aromatic structures in BC, due to the increase in pyrolysis temperature. Also, biochar demonstrated a Pb2+ adsorbed amount of 2.03 to 2.37 mg g–1 and a Ca2+ release capacity of 0.655 to 0.765 mg g–1. In this way, biochar produced from residues of cassava waste can be a viable strategy to enhance agricultural production and reduce environmental contaminants.

Preparation of C–SiC/ZrSixOyCz core-shell fibers by Coaxial electrospinning and the high-temperature performance

Core-shell ceramics fibers with multiple composition are ideal candidates for thermal insulation application at high temperature. Herein, ultrathin C–SiC/ZrSi x O y C z core-shell fibers were successfully fabricated by coaxial electrospinning and high temperature pyrolysis with polycarbosilane (PCS) as core precursor and Zirconium butoxide as shell precursor, respectively. The ceramics fibers revealed distinct core-shell partition. The average diameter was about 3 μm and the shell thickness increased to 500 nm with increasing pyrolysis temperature. Thermogravimetry analysis (TGA) results showed that the weight of the fibers reduced to 60% in Ar atmosphere and rose to 108% in O 2 atmosphere, which confirmed the excellent thermal stability and anti-oxidation properties due to the protection effect of shell layer and the self-healing mechanism. Moreover, the ceramics fibers maintained good flexibility and deformability. Such optimized anti-oxidation and mechanical performance indicates that the prepared core-shell fibers could be an excellent thermal insulation material for high temperature application.

Effect of pyrolysis temperature on adsorption and degradation of THI and IMI by biochar

In order to explore the effects of biochar prepared at different pyrolysis temperatures and different solid-liquid ratios on the adsorption and degradation of thiacloprid and imidacloprid in biochar, three biochar were prepared by oxygen pyrolysis with sawdust and as raw materials at 300, 500 °C and 600 °C respectively. The effects of biochar on the adsorption degradation of thiacloprid and Imidacloprid in biochar were studied. The results showed that the addition of biochar could significantly increase the soil pH, available phosphorus and organic carbon content, and reduce the soil H / C. The addition of biochar significantly improved the adsorption of thiacloprid and imidacloprid, and the adsorption capacity increased with the increase of biochar pyrolysis temperature. Biochar with different pyrolysis temperatures had different effects on the degradation of thiacloprid and imidacloprid. The strong adsorption capacity of high temperature biochar system reduces the chemical degradation rate of thiacloprid and imidacloprid. Proper solid-liquid ratio can avoid the waste of adsorbent and achieve the optimal utilization rate. Therefore, the types and properties of biochar should be fully considered when using biochar to repair pesticide contaminated soil.

Hierarchical Graphitic Carbon-Encapsulating Cobalt Nanoparticles for Catalytic Hydrogenation of 2,4-Dinitrophenol

Cobalt hierarchical graphitic carbon nanoparticles (Co@HGC) (1), (2), and (3) were prepared by simple pyrolysis of a cobalt phenanthroline complex in the presence of anthracene at different temperatures and heating times, under a nitrogen atmosphere. The samples were used for the catalytic hydrogenation of 2,4-dinitrophenol. Samples (1) and (3) were prepared by heating at 600 °C and 800 °C respectively, while (2) was prepared by heating at 600 °C with an additional intermediate stage at 300 °C. This work revealed that graphitization was catalyzed by cobalt nanoparticles and occurred readily at temperatures of 600 °C and above. The nanocatalysts were characterized by Scanning Electron Microscopy SEM, energy dispersive X-ray analysis EDX, Raman, Xrd, and XPS. The analysis revealed the presence of cobalt and cobalt oxide species as well as graphitized carbon, while TEM analysis indicated that the nanocatalyst contains mainly cobalt nanoparticles of 3–20 nm in size embedded in a lighter graphitic web. Some bamboo-like multiwall carbon nanotubes and graphitic onion-like nanostructures were observed in (3). The structures and chemical properties of the three catalysts were correlated with their catalytic activities. The apparent rate constants kapp (min−1) of the 2,4-dinitrophenol reductions were 0.34 for (2), 0.17 for (3), 0.04 for (1), 0.005 (no catalyst). Among the three studied catalysts, the highest rate constant was obtained for (2), while the highest conversion yield was achieved by (3). Our data show that an increase in agglomeration of the cobalt species reduces the catalytic activity, while an increase in pyrolysis temperature improves the conversion yield. The nanocatalyst enhances hydrogen generation in the presence of sodium borohydride and reduces 2,4-dinitrophenol to p-diamino phenol. The best nanocatalyst (3) was prepared at 800 °C. It consisted of uniformly distributed cobalt nanoparticles sheltered by hierarchical graphitic carbon. The nanocatalyst is easily separated and recycled from the reaction system and proved to be degradation resistant, to have robust stability, and high activity towards the reduction reaction of nitrophenols.

Mechanisms of emerging contaminants removal by novel neem chip biochar

Emerging contaminants (ECs) play a vital role in water pollution. The treatment methods used for the removal are expensive and complex. It is therefore highly needed to develop cost-effective materials for the effective removal of ECs. This study comprehensively investigated the potential of biochar material pyrolyzed at different temperatures in removing mancozeb, a potential EC, reported to significantly pollute water sources in Sri Lanka. Detailed isotherm, kinetics, thermodynamics and rate-limiting factor analysis were performed for biochar with high adsorptive capacity along with FTIR and XRD characterization. Results revealed that biochar pyrolyzed at 900 °C exposed higher adsorptive performance of 187.68 mg/g. Moreover, a detailed isotherm study exhibited that the adsorption of mancozeb to biochar is multilayer in nature. The pseudo second-order equation is well fitted to explain the adsorption rate of mancozeb. In addition, the thermodynamic analysis explains that the adsorption is spontaneous and endothermic. The XRD information well explains the carbon network development with an increase in pyrolysis temperature. At higher pyrolysis temperatures, the constricted carbon network was formed. FTIR analysis expresses that the functional groups are degraded at higher pyrolysis temperature. The rate-limiting analysis indicates that the removal rate of mancozeb by biochar derived from neem chips pyrolyzed at 900 °C initially induced by mass diffusion followed by intraparticle diffusion. The innovative finding of the use of biochar produced from neem chip for the removal of mancozeb makes an opening to the development of noval strategies for the effective removal of ECs at the commercial level.

Investigation on micro‐mechanism of palm oil as natural ester insulating oil for overheating thermal fault analysis of transformers

In order to explore the pyrolysis mechanism of palm oil as the natural ester insulating liquid from the molecular aspect, the ReaxFF reactive force field was used to simulate the pyrolysis process of palm oil. Firstly, the molecular models of the four main molecules of palm oil—tripalmitin, trilinolein, triolein, and tristearin—are constructed via density functional theory (DFT). Secondly, the vibrational frequencies of the four molecules are calculated, so as to calculate the infrared (IR) spectra. Thirdly, molecular dynamics (MD) simulations employing the ReaxFF method are performed to simulate the pyrolysis reaction of the palm oil system under different temperatures, so as to observe the generation pathways of major products used in the dissolved gas analysis (DGA) in the transformer thermal fault analysis. Finally, hydrogen bonds in the pyrolysis process are counted. It is found that the number of hydrogen bonds gradually increased with the increase of pyrolysis time and pyrolysis temperature. It reveals why the life of the insulating paper immersed with natural esters is prolonged, and why the breakdown voltage is reduced slowly in the actual experiment from another perspective. This study can provide theoretical guidance and effective reference for the thermal fault analysis of an insulating liquid using palm oil as raw material.

Comprehensive investigation on the gasification reactivity of pyrolysis residue derived from Ca-rich petrochemical sludge: Roles of microstructure characteristics and calcium evolution

Pyrolysis-gasification coupling process is an effective technology that can realize the thorough reutilization and clean disposal of petrochemical sludge. However, pyrolysis residue of petrochemical sludge (PRPS) produced at different temperatures possesses obviously different structure properties, which profoundly impacts the subsequent gasification. This study reveals the effect of pyrolysis degree of PRPS on the CO2 gasification reactivity by evaluating the micromorphology, pore property, existed form of calcium mineral and carbon structural characteristics. Results demonstrate that micromorphology development of the PRPSs with diverse pyrolysis degree (PRPS prepared at 500–900 °C) has three main stages, namely, the emergence of macropores and fissures (500–600 °C), the pore development (700–800 °C), and the pore jam (900 °C). The optimal PRPS was obtained at 800 °C-pyrolysis (800-PRPS) as the maximal specific surface area and desorption pores volume were observed. In addition, Raman analysis indicated that the 800-PRPS has the best carbon activity as well. By further increasing pyrolysis temperature to 900 °C, the carbon disordering, defect, and active sites of the PRPS decreased. Moreover, results of non-isothermal PRPS-CO2 reaction indicated that the basic calcium compound carbonation, gasification, calcium carbonate decomposition regimes were involved. Compared with 800–900 PRPSs, 500–700 PRPSs were more vulnerable in the lower gasification temperature owing to the more char matrix remain. In addition, owing to the occurrence of the carbonation reaction, the calcium carbonate product layer was formed and might affect the early-age gasification.

Pyrolysis of pellets prepared from pure and blended biomass feedstocks: Characterization and analysis of pellets quality

Recently, pyrolysis integrated with pelletization has received great attention. In the current study, various physical, mechanical, chemical and thermal characteristics of furfural residue pellets (FRPs), sewage sludge pellets (SSPs), furfural residue-sewage sludge pellets (FRSSPs) were studied at different pyrolysis temperature (200–850 °C) and residence time (15–45 min). The mass and energy yields of pellets dropped drastically with increasing pyrolysis temperature. Higher heating values (HHV) of pyrolysed furfural residue pellets (PYFRPs) and furfural residue-sewage sludge pellets (PYFRSSPs) increased from 22.22 to 26.76 MJ/kg, and 20.59–23.72 MJ/kg, respectively with increasing temperature from 200 to 850 °C. However, the HHV of pyrolysed sewage sludge pellets (PYSSPs) decreased with increasing temperature. The lowest pellet density and strength were found at 850 °C and residence time of 45 min. The pellets remained dimensionally stable during the water immersion test and after a storage time of 2 weeks, the relaxed densities and strength remained unchanged. The volumetric energy density of PYFRPs (30.35 kJ/m3) was found to be higher than PYSSPs (8.92 kJ/m3) and PYFRSSPs (23.85 kJ/m3) at the same process conditions. Thermal treatment enhanced the hydrophobicity of pellets. The lowest moisture uptake of 1.14 wt%, 1.8 wt%, and 1.58 wt% for the corresponding PYFRPs, PYSSPs and PYFRSSPs were observed at pyrolysis temperature of 300 °C. The maximum methylene blue and iodine adsorption values (i.e. 96 and 244.8 mg/g), (191 and 314.7 mg/g) and (121.6 and 263 mg/g) for PYFRPs, PYSSPs and PYFRSSPs were found, respectively, at temperature of ≥ 450 °C. Pyrolysis at higher temperature significantly reduced the heavy metals in PYFRSSPs and PYSSPs.

Electrochemical Stability of Platinum Nanoparticles Supported on N‐Doped Hydrothermal Carbon Aerogels as Electrocatalysts for the Oxygen Reduction Reaction

AbstractSustainable N‐doped carbon aerogels were synthesized by a scalable hydrothermal approach using low‐cost and abundant precursors such as glucose and ovalbumin. By adjusting the pyrolysis temperature (900–1500 °C), the surface chemistry, porosity and conductivity of these aerogels could be optimized for the design of Pt‐based oxygen reduction reaction (ORR) catalysts with high Pt loading (40 wt % Pt) and improved stability. Pt nanoparticle deposition was realized by wet impregnation followed by thermal reduction and their size and distribution was found to strongly depend on the surface chemistry of the carbon aerogels. The catalysts’ activities and stabilities, determined by rotating disc electrode measurements in HClO4, were found to strongly depend on the pyrolysis temperature of the N‐doped carbon aerogel supports. While the mass activity decreased with increasing temperature, in line with a decreasing ECSA related to an increase in Pt nanoparticle size, the long‐term stability of the catalysts, as revealed by accelerated stress tests for carbon support degradation (10,000 cycles), increased with increasing pyrolysis temperature, in line with increasing Pt nanoparticle sizes and increasing graphitization of the carbon aerogel supports. Most importantly, the catalyst derived from aerogels pyrolyzed at 1000 °C achieved a good compromise between activity and stability and revealed a superior ORR activity after the accelerated stress test in comparison to a commercially available Pt/C reference catalyst (40 wt % Pt).

Sorption of Cd(II) and Ni(II) on biochars produced in nitrogen and air-limitation environments with various pyrolysis temperatures: Comparison in mechanism and performance

N2 and air-limitation environments are two common pyrolysis atmospheres to produce biochars. However, their influence on the sorption mechanism and performance of biochar toward heavy metal ions (HMs) remains unknown. Hence, biochars produced in N2 and air-limitation environments at 300–750 °C were applied to sorb Cd(II) and Ni(II) in this study. The results show that the maximum adsorption quantities (Qm) of Cd(II) and Ni(II) on biochars of air-limitation pyrolysis were 1.08–1.84 folds and 1.66–3.11 folds, respectively, of those on biochars of N2 pyrolysis. The Qm of both studied HMs on biochars produced in the two studied atmospheres both generally improved with increasing pyrolysis temperature due to the increased contents of inorganic elements such as P, S, and Si at higher temperatures. Besides, the Qm of both studied HMs on biochars of N2 pyrolysis improved with the increasing graphitic C content. The results indicate the sorption mechanism of HMs on biochars of air-limitation pyrolysis was dominated by the mineral anions complexation, while the sorption mechanism of HMs on biochars of N2 pyrolysis was controlled by both the mineral anions complexation and cation-π interaction. Additionally, the protonated oxygen-containing groups (e.g., hydroxyl groups) linked to C fraction possibly formed hydrogen-bonds with mineral anions and thus suppressed the sorption of HMs on biochars. A pyrolysis condition of the maximum adsorption efficiency for HMs is the N2 pyrolysis at 750 °C. The results of this study are beneficial for selecting suitable pyrolysis methods to produce biochars and raising their efficiency in HMs sorption.

Investigation of the CN and C2 emission characteristics and microstructural evolution of coal to char using laser-induced breakdown spectroscopy and Raman spectroscopy

Laser-induced breakdown spectroscopy (LIBS) was employed to study the spectral characteristics of the C2 and CN emissions of three types of coal and their pyrolysis char samples. By analysing the atomic and molecular emissions, the electron temperature, electron density and rotational temperature were calculated to evaluate the characteristics of the laser-induced plasma. The correlation between the molecular emissions and coal combustion characteristics was also investigated, which was explained from the aspect of microstructural evolution obtained by Raman spectroscopy. The molecular emissions were gradually inhibited with increasing pyrolysis temperatures, however the molecules tended to distribute at a higher equilibrium temperature. The rotational temperatures increase by 1000–3300 K relative to the raw coal for chars prepared at pyrolysis temperatures of 293–1173 K. The reduction of C2 and CN emissions, which are thought to be mainly caused by small aromatic rings and amorphous carbon structures, is consistent with the Raman spectroscopy results in that the microstructures evolve towards a more stable large aromatic-ring skeleton after pyrolysis. When the carbon conversion ratio is Xc = 50% for three kinds of coal, the R2 values of the exponential fitting between C2 emission and carbon conversion rate are all higher than 0.99.

Tracing Organic-Inorganic Interactions by Light Stable Isotopes (H, Li, B, O) of an Oil-Bearing Shale and its Clay Fraction During Hydrous Pyrolysis

AbstractTracing interactions during burial-induced organic maturation and associated clay-material alteration is of prime importance for understanding both the individual and combined mineral and organic processes. In the present study the light elements B, Li, O, and H of a sample from oil-prone Eocene Kreyenhagen Shale from San Joaquin Basin (California) were examined. The natural burial-induced temperature increase was simulated by pyrolysis experiments at progressively increasing temperatures (270–365°C) and for varied durations (72–216 h) applied to the whole rock and its <2 μm fraction. The illite structure as well as the K-rich interlayers of the illite-smectite mixed layers were not affected by the pyrolysis experiments and the smectite-rich interlayers did not collapse, while the soluble minerals and the organic matter were altered. The distribution pattern of the rare-earth elements (REEs) from untreated whole rock and of its pyrolyzed equivalents are within analytical uncertainty, which confirms that the changes induced by pyrolysis experiments were minimal in the bulk sample. Conversely, the REEs from the <2 μm fractions were modified significantly, suggesting that the whole rocks and the <2 μm fractions may contain different types of organic materials. Also, only the carbonates, oxides, chlorides, and organic matter were affected together with the smectite-rich interlayers of the illite-smectite structure. Bitumen coating of the smectite interlayers probably increased the amount of B of organic origin in their sites. The δ11B and δ7Li of the successively expelled hydrocarbon phases changed with increasing pyrolysis temperatures, together with the B and Li contents of the hydrocarbon-related fluids. On the basis of the δ11B and δ7Li from pyrolyzed clay fractions, the B released successively was not isotopically homogeneous, probably depending on how the type of organic matter decomposed during the successive pyrolysis steps, and on which components were released. The δ11B of organic-B increased progressively from –2‰ at low experimental temperature up to +9‰ at the highest temperature. The calculated δ7Li that was released also increased relative to the value of the outcropping sample used as a reference, but it remained almost constant from –7‰ at 310°C for 72 h to –8‰ at 365°C for 216 h. The δ18O values of the <2 μm size fractions decreased significantly during pyrolysis above 300°C, but the δD changes were rather modest. The total organic carbon (TOC) remained statistically constant after pyrolysis to 300°C, as did the δ7Li values. The pyrolysis experiments in the present study suggest the presence of bitumen-coated smectite interlayers that could have been misidentified as dehydrated smectite in the literature. Together with abnormal illite K-Ar ages, the occurrence of such bitumen-coated illite-smectite interlayers occurring in source and reservoir rocks could indicate the timing of hydrocarbon maturation relative to illitization.

Effect of pyrolysis temperature on blast furnace injection performance of biochar

As a carbon–neutral fuel, biomass plays a prominent role in replacing fossil fuels. The objective of this research is to uncover the influence of pyrolysis temperature on the metallurgical properties of biochar, as well as to provide a theoretical reference for the preparation of biochar suitable for blast furnace injection. The metallurgical properties of biochar have been systematically studied through the comparative analysis of the physical and chemical properties of biochar. The results show that pyrolysis technology can effectively improve the fuel performance of biomass. As the pyrolysis temperature increases, the fuel performance of biochar increases, the carbonization degree gradually increases, and the combustion performance and reactivity gradually weaken, approaching carbonaceous materials. The Coats-Redfern kinetic equation is used for the kinetic fitting of the combustion process of biochar, and has achieved good results. This clarifies the speed control link in the combustion process of biochar.

Upgrading biochar by co-pyrolysis of heavy bio-oil and apricot shell using response surface methodology

In this study, heavy bio-oil (HB) and apricot shell (AS) were used as raw materials to produce biochar by co-pyrolysis in a tube furnace. Three operational factors were assessed, namely pyrolysis temperature (400–700 °C), residence time (5–20 min) and percentage of HB (0–100%), with the effects on the yield and properties of biochar comprehensively investigated using a response surface methodology. Results showed that the mass yield, fixed carbon content, carbon content, and high heating value (HHV) of co-pyrolysis biochar (550 °C, 12.5 min, and an AS/HB mass ratio of 1:1) were 29.33%, 81.84%, 82.91%, and 32.97 MJ/kg, respectively. The experimental values for the co-pyrolysis biochar were 1.52%, 5.30%, 1.82%, and 1.12 MJ/kg higher than their corresponding theoretical values, respectively. However, the oxygen content of co-pyrolysis biochar was 1.71% lower than the theoretical value. Meanwhile, the C/H ratio of biochar improved with increasing pyrolysis temperature, residence time and percentage of HB, indicating higher biochar aromaticity. The evolution of surface functional groups indicated that an increase in pyrolysis temperature and residence time reduced the intensity of CO and C–O absorption peaks, while an increase in the percentage of HB enhanced the intensity of the C–O absorption peak of biochar. In general, compared to the pyrolysis of HB and AS alone, co-pyrolysis of HB and AS exerted a synergistic impact, improving the mass yield and fuel quality of biochar. Finally, the relationships between properties (mass yield, element content, proximate analysis parameters, and HHV) and the three varied factors were established, providing guidance for effective upgrading of biochar by co-pyrolysis of HB and biomass.

Efficiency and mechanisms of Sb(III/V) removal by Fe-modified biochars using X-ray absorption spectroscopy

Fe-modified biochars (FeBC) are effective antimony (Sb) removal materials; however, the removal mechanisms require further investigation. In this study, aqueous Sb(III) and Sb(V) removal by FeBC (300, 600, and 900 °C) was evaluated, with the adsorption mechanisms investigated using X-ray absorption spectroscopy (XAS). Screening results (based on removal efficiencies) using different types of FeBC indicated the 900 °C FeCl3-modified biochar (FeCl3BC900) achieved the best Sb(III/V) removal performance. The kinetics of the Sb(III/V) removal process were best fitted by a pseudo-second-order model. Additionally, the isothermal results were described by Langmuir and Redlich-Peterson models. Aqueous analysis and X-ray absorption near-edge structure data fitting indicated Sb(III) was oxidized to Sb(V) in the Sb(III)-spiked system, and the oxidation extent increased with increasing pyrolysis temperature. The oxidation process rapidly occurred in both the solution and biochar. No Sb(V) was reduced to Sb(III) in the Sb(V)-spiked system. The XAS results of the isothermal experiment indicated the oxidation capacity of FeCl3BC900 was limited for high initial Sb(III) concentrations. The Sb-Fe1 and Sb-Fe2 bonding distances were 3.05–3.10 and 3.47–3.54 Å, respectively, indicating inner-sphere complexes were formed during the Sb(III/V) removal processes. The Sb(III/V) removal mechanisms included electrostatic adsorption, inner-sphere complexes, and coprecipitation. Oxidation was also involved in Sb(III) removal.