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Porous graphene has attracted considerable attention for its promising potential application in energy storage devices due to its unique porous structure combined with inherent electronic characteristics of graphene. Herein, a cost effective and environmentally friendly strategy is developed to prepare porous graphene via graphitization coupled with liquid oxidation-rapid thermal reduction using anthracite as a precursor. The prepared porous graphene has microstructure features such as highly continuous corrugated nanosheets with micro-meso-macro hierarchical porous structure, high specific surface area (640 m2 g−1) and large pore volume (3.792 cm3 g−1) with large amount of structural defects and nanopores, which provides sufficient active sites for lithium ions storage and offers favorable pathways for the fast transportation of lithium ions and electrons. When used as anode materials for lithium-ion batteries, such porous graphene exhibits a high reversible capacity of 770 mAh·g−1 at current density of 0.1 C, and possesses an outstanding rate capability with desirable capacities of 274 mAh·g−1 and 224 mAh·g−1 even at high current densities of 10 C and 20 C. Moreover, such porous graphene also demonstrates superior cycling performance up to 98.0% of the initial reversible capacity retention after 110 cycles. This study paves a promising approach to the large-scale production of porous graphene from coal for high performance anode materials used in lithium-ion batteries.

Time-varying formation analysis and design problems for general linear multi-agent systems with switching interaction topologies and time-varying delays are studied. Firstly, a consensus-based formation control protocol is constructed using local information of the neighboring agents. An algorithm with three steps is presented to design the proposed formation control protocol. Then, based on linear matrix inequality technique and common Lyapunove–Krasovskii stability theory, sufficient conditions for general linear multi-agent systems with switching topologies and time-varying delays to achieve time-varying formation are given together with a time-varying formation feasibility condition. Finally, a numerical simulation is given to demonstrate the effectiveness of the obtained theoretical results.

Microwave-assisted chemical vapor deposition (CVD) was employed for the synthesis of carbon nanotubes (CNTs) on pine nut shell (PNS) chars. The impact of reaction temperature, catalyst, carbon source, and the renewable carbon substrate on the synthesis of the CNTs were investigated. Microwave irradiation, the type of carbon source, and the presence of nickel catalyst were found to be the governing factors during the formation and growth of CNTs at low temperatures. 600 °C was found to be the optimum temperature for the formation of the CNTs. The high-resolution transmission electron microscope (HRTEM) results showed that the CNTs synthesized at 600 °C had a multiwall structure and a d-spacing of 0.34 nm. The diameter and length of CNTs were ~50 nm and 2600–3200 nm, respectively. Raman spectroscopy analysis revealed that a high degree of carbon order was achieved at 600 °C due to the formation of CNTs on the surface of bio-char. The formation and growth mechanisms of CNTs under microwave irradiation were proposed and discussed.

This paper investigates the time-varying formation tracking (TVFT) problems for unmanned aerial vehicle (UAV) swarm systems with the leader’s unknown input and collision and obstacle avoidance mechanism. To solve the TVFT control problem which has not been studied extensively, distributed observers are proposed to estimate the leader’s position and a TVFT control protocol is constructed. Stability of control protocol is proved by Lyapunov stability theory. Furthermore, the effectiveness of the TVFT control protocol is verified by numerical simulations and flying experiments, which is more convincing than the theoretical results only.

The impact of pressure on the carbon structure of a Chinese bituminous coal was investigated using a pressurized entrained-flow reactor in the temperature and pressure ranges of 700-900 °C and 0.1-4.0MPa, respectively. Pyrolysis pressure had a significant influence on the physiochemical and carbon structure of chars. The specific surface area and the swelling ratio of chars reached their highest values at 1.0MPa. Fourier transform infrared spectroscopy (FTIR) analysis showed that higher pressures enhanced the decomposition of functional groups in chars. Raman spectroscopy analysis results revealed that at elevated pressures, the organic matrix and functional groups were removed from the char structure, leading to higher ordering of the carbon structure. During X-ray diffraction (XRD) analysis, parameters such as the stacking height (Lc), interlayer spacing (d002) and lateral size of the graphite structures (La) were used to evaluate the graphitic structures in chars. The results showed an increase in Lc, La, and the average number of graphene sheets with pyrolysis pressure, indicating a more ordered carbon structure at elevated pressures. The d-spacing of char was in the range of 3.34-3.37 A, similar to typical graphitic structures.

The chemistry of the plastic layer in a coke oven plays a critical role in coke-making and has a great impact on coke quality. In this study, progressive changes of the plastic layer were investigated using a combination of analytical methods. Three Australian coking coals with different vitrinite contents were used to produce plastic layer samples using a 4 kg lab-scale coke oven. The plastic layer samples were analysed by means of Synchrotron micro-CT scanning and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) analysis to delineate the characteristic regions of each layer. The peak separation and quantitative calculation of FTIR spectra allowed the analysis of changes in structural parameters and functional groups of each plastic layer. The results showed drastic changes in physical and chemical structures of the plastic layer samples for all coals tested and were also strongly influenced by coal type. For the high-vitrinite coals, it seems that relatively larger amounts of the plastic mass were developed due to the timely rupture of large number of the bridge bonds in the intermediate plastic regions and efficient hydrogen transfer to stabilize the radicals generated. This led to a more drastic growth of pores and larger maximized porosities in the intermediate plastic regions. Conversely, the low-vitrinite coal was assumed to form lower amount of the plastic mass in the intermediate plastic region due to less rupture of aliphatic bridge bonds and inefficient hydrogen transfer. This was attributed to a lower degree of the pore development and the lower porosity observed in the region.

Mitochondrial DNA (mtDNA) encodes several key components of respiratory chain complexes that produce cellular energy through oxidative phosphorylation. mtDNA is vulnerable to damage under various physiological stresses, especially oxidative stress. mtDNA damage leads to mitochondrial dysfunction, and dysfunctional mitochondria can be removed by mitophagy, an essential process in cellular homeostasis. However, how damaged mtDNA is selectively cleared from the cell, and how damaged mtDNA triggers mitophagy, remain mostly unknown. Here, we identified a novel mitophagy receptor, ATAD3B, which is specifically expressed in primates. ATAD3B contains a LIR motif that binds to LC3 and promotes oxidative stress‐induced mitophagy in a PINK1‐independent manner, thus promoting the clearance of damaged mtDNA induced by oxidative stress. Under normal conditions, ATAD3B hetero‐oligomerizes with ATAD3A, thus promoting the targeting of the C‐terminal region of ATAD3B to the mitochondrial intermembrane space. Oxidative stress‐induced mtDNA damage or mtDNA depletion reduces ATAD3B‐ATAD3A hetero‐oligomerization and leads to exposure of the ATAD3B C‐terminus at the mitochondrial outer membrane and subsequent recruitment of LC3 for initiating mitophagy. Furthermore, ATAD3B is little expressed in m.3243A > G mutated cells and MELAS patient fibroblasts showing endogenous oxidative stress, and ATAD3B re‐expression promotes the clearance of m.3243A > G mutated mtDNA. Our findings uncover a new pathway to selectively remove damaged mtDNA and reveal that increasing ATAD3B activity is a potential therapeutic approach for mitochondrial diseases.

Highlights • Ice nucleation in fine water droplets triggered by weak ultrasonic vibrations. • Ice nucleation onset sites sit between the particle and the vibrating substrate. • The collapse of cavitation bubbles in the particle crevice is structure sensitive., Water with small volume (a few microlitres or less) often maintains its liquid state even at temperatures much lower than 0 °C. In this study, we examine the onset of ice nucleation in micro-sized water droplets with immersed solid particles under weak ultrasonic vibrations. The experimental results show that ice nucleation inside the water droplets can be successfully induced at relatively high temperatures. The experimental observations indicate that the nucleation sites are commonly encountered in the region between the particle and the substrate. A numerical study is conducted to gain insight into the possible underlying phenomenon for ice nucleation in such systems. The simulation results show that the collapse of cavitation bubbles in the crevice at the particle surface is structure sensitive with the hemisphere-shape crevice generating pressures as high as 1.63 GPa, which is theoretically suitable for inducing ice nucleation.

This paper focuses on the finite-time output containment problem for a kind of nonlinear multi-agent systems with multiple dynamic leaders. Firstly, considering the topological structure among the followers, a kind of adaptive distributed observer is designed to estimate the whole states of all the leaders. By utilizing common Lyapunov theory, the finite-time convergence of proposed distributed observer is proved. On the basis of this conclusion, a containment control protocol including the desired convex combinations of the leaders is developed for each follower by using the given weights. With the help of the output regulation theory, the finite-time output containment criterion for nonlinear multi-agent systems is derived. Finally, a numerical example is presented to demonstrate the effectiveness of the theoretical results.

A series of Mn0.15Fe0.05/fly-ash catalysts have been synthesized by the co-precipitation method using coal fly ash (FA) as the catalyst carrier. The catalyst showed high catalytic activity for low-temperature selective catalytic reduction (LTSCR) of NO with NH3. The catalytic reaction experiments were carried out using a lab-scale fixed-bed reactor. De-NOx experimental results showed the use of optimum weight ratio of Mn/FA and Fe/FA, resulted in high NH3-SCR (selective catalytic reduction) activity with a broad operating temperature range (130&ndash, 300 &deg, C) under 50000 h&minus, 1. Various characterization methods were used to understand the role of the physicochemical structure of the synthesized catalysts on their De-NOx capability. The scanning electron microscopy, physical adsorption-desorption, and X-ray photoelectron spectroscopy showed the interaction among the MnOx, FeOx, and the substrate increased the surface area, the amount of high valence metal state (Mn4+, Mn3+, and Fe3+), and the surface adsorbed oxygen. Hence, redox cycles (Fe3+ + Mn2+ &harr, Mn3+ + Fe2+, Fe2+ + Mn4+ &harr, Mn3+ + Fe3+) were co-promoted over the catalyst. The balance between the adsorption ability of the reactants and the redox ability can promote the excellent NOx conversion ability of the catalyst at low temperatures. Furthermore, NH3/NO temperature-programmed desorption, NH3/NO- thermo gravimetric-mass spectrometry (NH3/NO-TG-MS), and in-situ DRIFTs (Diffuse Reflectance Infrared Fourier Transform Spectroscopy) results showed the Mn0.15Fe0.05/FA has relatively high adsorption capacity and activation capability of reactants (NO, O2, and NH3) at low temperatures. These results also showed that the Langmuir&ndash, Hinshelwood (L&ndash, H) reaction mechanism is the main reaction mechanism through which NH3-SCR reactions took place. This work is important for synthesizing an efficient and environmentally-friendly catalyst and demonstrates a promising waste-utilization strategy.

Time-varying formation tracking of multiple surface vessels system is considered. Firstly, the interaction topology and the time-varying formations of multiple surface vessels are established based on algebraic graph theory. Secondly, the cubic spline interpolation method is used to obtain the desired trajectory when only several path points are given. Thirdly, for leader ship, trajectory tracking control law of outer loop and robust attitude tracking law of inner loop are designed based on the idea of virtual leader. Fourthly, for multiple follower vessels, a distributed time-varying formation tracking control law using only neighboring relative information is designed in the outer loop, and a robust attitude tracking law is designed in the inner loop. In attitude tracking, sliding mode control method is utilized to control the course angle and navigation speed, which eliminates the influence of model parameter perturbation and external disturbances such as wind, wave and current in vessel motion. Finally, numerical simulation results are given to confirm the effectiveness of the acquired theories.

This study addresses the in-situ microwave catalytic reforming of volatile matter from palm kernel shell (PKS) over iron-loaded activated carbon (Fe/AC) catalysts. The impacts of catalyst composition on the secondary gas-phase reactions and distribution of products were studied at 500 °C. It was found that the Fe/AC catalyst promoted the yield of light gases. Using the 1%-Fe/AC catalyst, the yield of gaseous fraction peaked at 37.09 wt%. The selectivity of the deoxygenated products was promoted in the presence of Fe. Catalytic reforming of PKS pyrolysis vapors over Fe/AC drastically enhanced the generation of phenol and H2, the concentrations of which reached 75.09 area% and 75.12 vol%, respectively. Catalytic pyrolysis of syringol and guaiacol as model compounds showed that Fe/AC catalyst promoted the demethoxylation and deoxygenation reactions to selectively generate phenol which was explained by oxophilic reactivity of the active Fe sites.

Alternative fuels are still needed to compensate for the energy shortages caused by fossil fuel depletion. The paper aims to brief the types of alternative fuels used for the past 30 years. Moreover, it includes the recent types of biofuels (especially biodiesel) and their blends with studies on the performances and the exhaust emissions for different engines. In this study, previous studies were analysed, the challenges faced by the researchers were examined, and incentives for using biodiesel fuel in engines were discussed. The engine performance and emissions when using biodiesels and their blends in different engine models were also surveyed. All biodiesels and their blends have demonstrated the ability to reduce emissions such as carbon oxide (CO), carbon dioxide (CO2), nitrogen oxide (NOx), particulate matter (PM) and hydrocarbon (HC) under various operating conditions, as well as the ability to improve the performance of the gas turbine. It is necessary to understand the combustion properties of fuels for their use in an engine. The contribution of this review is to help the engine manufacturers and researchers develop further research relating to readjusting and optimising the biodiesel engine and its relevant system.

Practical time-varying formation tracking analysis and design problems for multiple non-holonomic mobile robot systems with directed interaction topologies are investigated by using the distributed extended state observers, where the practical time-varying formation tracking error is controlled within an arbitrary small bound. Different from the previous work, the dynamics of each robot is non-holonomic and the followers are required to form the practical time-varying formation with respect to the leader of unknown control inputs. Besides, the disturbances and the uncertainties are considered in the dynamic model of the follower. Distributed extended state observers are constructed by using only the neighbouring relative information to estimate both the state and the unknown control inputs of the leader simultaneously. A practical time-varying formation tracking protocol is presented based on the distributed extended state observers. The gain matrices of the observers in the practical time-varying formation tracking protocol can be obtained by solving three linear matrix inequalities. Moreover, the stability of the multiple non-holonomic mobile robot system under the proposed protocol is proved by using the properties of the Laplacian matrix and the Lyapunov stability theory. Finally, two numerical simulation examples are given to illustrate the effectiveness of the obtained theoretical results.

The transformation of nitrogen in microalgae during entrained-flow pyrolysis of Chlorella vulgaris was systematically investigated at the temperatures of 600–900 °C and pressures of 0.1–4.0 MPa. It was found that pressure had a profound impact on the transformation of nitrogen during pyrolysis. The nitrogen retention in bio-char and its content in bio-oil reached a maximum value at 1.0 MPa. The highest conversion of nitrogen (50.25 wt%) into bio-oil was achieved at 1.0 MPa and 800 °C, which was about 7 wt% higher than that at atmospheric pressure. Higher pressures promoted the formation of pyrrolic-N (N-5) and quaternary-N (N-Q) compounds in bio-oil at the expense of nitrile-N and pyridinic-N (N-6) compounds. The X-Ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) results on bio-chars clearly evidenced the transformation of N-5 structures into N-6 and N-Q structures at elevated pressures. The nitrogen transformation pathways during pyrolysis of microalgae were proposed and discussed.

Pressurized entrained-flow pyrolysis of Chlorella vulgaris microalgae was investigated. The impact of pressure on the yield and composition of pyrolysis products were studied. The results showed that the concentration of H2 in bio-gas increased sharply with increasing pyrolysis pressure, while those of CO, CO2, CH4, and C2H6 were dramatically decreased. The concentration of H2 reached 88.01 vol% in bio-gas at 900 °C and 4 MPa. Higher pressures promoted the hydrogen transfer to bio-gas. The bio-oils derived from pressurized pyrolysis were rich in nitrogen-containing compounds and PAHs. The highest concentration of nitrogen-containing compounds in bio-oil was achieved at 800 °C and 1 MPa. Increasing pyrolysis pressure promoted the formation of nitrogen-containing compounds such as indole, quinoline, isoquinoline and phenanthridine. Higher pyrolysis pressures led to increased sphericity, enhanced swelling, and higher carbon order of bio-chars. Pressurized pyrolysis of biomass has a great potential for poly-generation of H2, nitrogen containing compounds and bio-char.

An earth-abundant and low cost bituminous coal was used as precursor to prepare synthetic graphite materials through preliminary carbonization coupled with further high temperature graphitization treatment at 2000–2800 °C. The microstructure characteristics of the obtained synthetic graphite materials were characterized by means of X-ray diffraction, scanning electron microscope, transmission electron microscope, Raman spectroscopy and nitrogen adsorption–desorption. The results show that the microstructures of synthetic graphite materials are strongly dependent on the graphitization temperature. The synthetic graphite graphitized at 2800 °C has perfect ordered layered structure with high graphitization degree and relatively large surface area with well-developed mesopores, which offers a favorable pathway for the electrochemical intercalation-deintercalation of lithium ions in carbon matrix. Such synthetic graphite applied as anode materials for lithium-ion batteries presents a maximum reversible capacity of 310.3 mAh·g − 1 at current rate of 0.1C and still remains as high as 143.9 mAh·g − 1 at current rate of 5C. Moreover, the synthetic graphite also exhibits superior rate capability and outstanding cycling performance with over 95.3% initial capacity retention after 100 cycles. This study demonstrates a promising feasibility for large-scale production of synthetic graphite materials from bituminous coal for high performance lithium-ion batteries.

Practical time-varying formation tracking analysis and design problems for high-order nonlinear multi-agent systems are investigated, where the time-varying formation tracking error is cont...

Time-varying formation tracking problems for high-order multi-agent systems with switching topologies are investigated. Different from the previous work, the states of the followers form a predefined time-varying formation while tracking the state of the leader with bounded unknown control input. Besides, the communication topology can be switching, and the dynamics of each agent can have nonlinearities. Firstly, a nonlinear time-varying formation tracking control protocol is presented which is constructed using only local neighboring information. Secondly, an algorithm with four steps is proposed to design the time-varying formation tracking protocol, where the time-varying formation tracking feasibility condition is introduced. Thirdly, by using the Lyapunov theory, the stability of the proposed algorithm is proven. It is proved that the high-order multi-agent system with switching topologies achieves the time-varying formation tracking if the feasibility condition holds and the dwell time is larger than a positive constant. Finally, a numerical example with six followers and one leader is given to demonstrate the effectiveness of the obtained results.

Hollow carbon nanofibers (HCNFs) were formed on the bio-char surface during microwave pyrolysis of pine nut shell in the temperatures range of 400–700 °C without the use of any additional catalyst, except activated carbon added as a microwave absorber. Scanning electron microscopy (SEM) analysis showed that HCNFs were only formed on microwave pyrolysis chars and not fixed-bed chars, suggesting that microwave irradiation had a major influence on their formation. High resolution transmission electron microscope (HRTEM) results showed that the synthesized HCNFs at 500 °C and 600 °C had a diameter of about 400 nm and length of 1400–5000 nm. HCNFs had multi-walled structure with a d-spacing of about 0.35 nm. Unlike fixed-bed bio-chars, the X-ray diffraction (XRD) analysis of the microwave bio-chars showed typical graphite peak at around 2θ = 26.3° with the strongest peak observed in 600 °C bio-char. Raman spectroscopy analysis revealed that the highest degree of carbon order of HCNFs was achieved at 600 °C, which agreed well with XRD analysis results. Detailed analysis of the volatiles evolved during microwave pyrolysis suggested that hydrocarbons in bio-oil such as benzene and alkenes and CO, CO2, methane, and ethane in bio-gas acted as the carbon source during formation of HCNFs.

Tar removal plays a key role in the process efficiency and viability of biomass gasification for syngas production applications. Among currently available tar treatment technologies, catalytic cracking was found to be the most attractive due to minimal energy losses by avoiding cooling of the raw product gas. Naturally available calcium-based catalysts, particularly stone dust and dolomite, have been proven to be effective for biotar cracking; however, they have poor resistance to attrition and undergo deactivation after a few carbonation/calcination cycles. As such, these characteristics play a critical role in determining the viability of their application at a large-scale. Hence to overcome the shortcomings previously stated, a novel dual supported calcium-based catalyst which includes a stable support with great mechanical strength (alumina, Al2O3, and mayenite, Ca12Al14O33) dosed with CaO nanoparticles was synthesized by wet impregnation of calcium on alumina particles with and without the assistance...

Bio-char has been applied to soil as an amendment to improve soil water holding capacity due to its porous nature. In this study the behavior of water in bio-char was investigated for better understanding mechanisms of water retention by bio-char. Bio-chars with different structures were prepared by partial gasification of peanut shell (PT) and palm kernel shell (PKS). It was observed that the BET surface area and total pore volume of bio-char increased with gasification conversion. Water holding capacity and water adsorption rate showed a direct correlation with micropore volume of bio-char, suggesting that physical structure of bio-char played a key role during interaction with water. These results indicated that partial gasification is a promising method for production of bio-char suitable for soil remediation. Two types of freezable water i.e. freezable free water (FFW) and freezable bound water (FBW) were directly detected in bio-char samples during Differential Scanning Calorimetry (DSC) analysis. The phase transition temperature of freezable bound water correlated well with pore size distribution of bio-chars. The presence of non-freezable (NFW) water in bio-char was also confirmed from the difference between total water content of samples and the sum of FFW and FBW. The amount of FFW showed an indirect correlation with micropore volume of bio-chars, suggesting that FFW is present in macropores. However, an opposite trend was observed for FBW and NFW in bio-chars, indicating that these two types of water were present in micropores. The low-temperature XRD results were used to define the boundary between the freezable and non-freezable water in bio-char samples.

Catalytic graphitization of biomass-based carbon has been used to synthesize graphene nanostructures with extraordinary electrochemical properties. To further improve the structural properties of these graphene nanostructures, it is critical to gain a deeper understanding of the formation mechanism and influence of process variables on the structural features of the resulting material. Here, we report the impact of various parameters such as catalyst loading, temperature, holding time, and catalyst salt precursor on the low-temperature catalytic graphitization of activated carbon (AC). Quantitative X-ray diffraction (XRD) analysis results show that at 20 wt% catalyst loading, reaction temperature of 1400 °C, and holding time of 30 min, a complete graphitization of amorphous carbon was achieved. In situ XRD and transmission electron microscopy (TEM) results indicated that the dissolution-precipitation and metal-induced graphitization are the primary mechanisms under which graphitized carbon was formed. Furthermore, it was found that the rate of graphitization under microwave irradiation is significantly higher than conventional heating, mainly owing to the enhanced precipitation of graphitic carbon caused by both carbon saturation and temperature fluctuation of the catalyst particles.

This work introduces nanostructured carbon-based composite with enriched CNTs and microstructural defects from pomelo peel biomass precursors through successive chemical pretreatment, heteroatom N, S dual-doping and transition metal oxide loading (Ta2Oy) and its application for electrochemical oxygen reduction reaction (ORR) at room temperature. During the microwave pyrolysis process, volatile N, S-containing species from trithiocyanuric acid reactant were trapped and doped into carbonaceous biomass precursor to achieving the rich-defect porous nanotubes and abundant cavity structure. The effect of biomass pretreatment on the textural and structural properties of biochar and formed CNTs were systematically investigated. The impacts of single doping (N) using melamine and dual-doping (N, S) with trithiocyanuric acid on the structural and electrochemical characteristics of biochar were evaluated. An optimized PP-NS-600-Ta-900 electrocatalyst displayed remarkable ORR activity with a half-wave potential of 0.82 V (vs. RHE), a limiting current density of −5.75 mA cm−2 and an electron transfer number of 3.85. The results offer a useful archetypical template to design and construct reliable CNTs enriched biomass-derived biochar for possible electrochemical energy and storage application, illustrating its viability for utilization as ORR electrocatalyst in potential applications, like fuel cells and metal-air batteries.

A series of novel iron-based deep eutectic solvents (DESs) as denitrification sorbents were evaluated to capture NO from simulated flue gases. The application of Fe(II) EG-ChCl DESs demonstrated the efficiency of absorption performance with the complete removal of NO and zero secondary pollution. In this study, mixtures of Ferric chloride (FeCl2), Ethylene glycol (EG), and Choline chloride (ChCl) were prepared using Fe(II) EG-ChCl DESs. Experimental results showed that the best performance for denitrification was achieved when DES solutions were treated at 60 °C, the gas flow rate of 50 mL/min, 5% partial pressure of steam, and the concentration of Fe(II) was 0.1 mol/L. Furthermore, excellent stability for denitrification was observed for the Fe(II) EG-ChCl DESs during five absorption–desorption cycles. The absorption reaction of Fe(II) EG-ChCl DESs maintained a first-order reaction kinetics with a reaction rate constant of 1.1 × 106 (L/mol·s) for the denitrification reaction. The FT-IR result indicated that there was a chemical interaction between Fe2+ and NO, and Fe2+ was the absorptive active species.

The presence of kaolinite as mineral in coal may significantly influence coking properties of coal, therefore affects quality of coke that is produced from such coals. In this paper, the effect of kaolinite addition on pyrolysis behaviour of coal was examined by blending kaolinite with a medium rank, high vitrinite, low ash coal. Thermoplasticity of coal was characterised by using a Gieseler Plastometer. Char and tar samples were collected through pyrolysis at 450 °C in a Gray-King apparatus. The functional groups of the char samples were measured using FT-IR spectroscopy, while tar compositions were characterised using GC/MS. The results indicated that under the test conditions, addition of up to 5 wt% of kaolinite could increase the coal fluidity, attributed to the decrease in CH 3 /CH 2 ratio in the residual char. The proportion of C O/C C bonds affected the plastic range. Furthermore, the results showed that kaolinite addition suppresses the evolution of low molecular compounds in tar phase. This study provides useful information for optimising coal blending in cokemaking industry.

This study reports the synergy effect during co-pyrolysis of Hailar lignite (HL) and palm kernel shell (PKS) biomass under microwave irradiation in the temperature range of 400–600 °C. The results showed that the synergy effect promoted the yields of tar and gas during co-pyrolysis experiments. Gas chromatography-mass spectrometry (GC–MS) analysis of tar showed that the formation of aliphatic hydrocarbons was promoted during co-pyrolysis of lignite and PKS biomass in expense of single-ring aromatic compounds, aliphatic carboxylic acids, alcohols, aldehydes, and ketones. The synergy effect also promoted the formation of H2 and CO during co-pyrolysis. A two-stage pyrolysis reactor was used in order to investigate the mechanism of synergy during co-pyrolysis by isolating the secondary pyrolysis reactions. The two-stage pyrolysis results showed that secondary pyrolysis reactions were mainly responsible for synergy effect, resulting in higher gas and lower tar yields as a result of secondary tar cracking. HL and PKS chars promoted the formation of aliphatic hydrocarbons, CO, and CH4 as a result of decarbonylation, decarboxylation, and demethylation reactions. Reforming of methane over HL and PKS chars led to an increase in concentrations of H2 and CO during secondary pyrolysis reactions.

Gas turbines are designed to run on specific fuels such as conventional fuels, so researchers are working to find alternative fuels as biodiesel. The purpose of this study is predicting the engine performance and emissions rate for the KingTech K180 turbojet engine running on dual biodiesel and its blend with Jet-A fuel. Besides that, this paper explores the different effect between dual blends and single blend. The fuel parameters were calculated based on each fuel's physicochemical properties to produce nine different blends of dual biodiesel (B10-Jet, B30-Jet, B50-Jet, B70-Jet, and B90-Jet) and a single biodiesel blend (POME50: Jet-A50). Then the heat of combustion for each blend was obtained using the GasTurb Details-6. After that, the design point was determined of the specific engine and operates it using alternative fuels to analyze the performance and emissions characteristics (CO, CO2, and NOx). This study found that the B10-Jet blend gave the best specific fuel consumption (SFC) value, 42.43 (g/kN.s). It also produced a lower emissions rate for CO and CO2 than Jet-A fuel and other blends. While emission index NOx was high for all blends, except B10-Jet fuel value was close to Jet-A fuel emission value.

Distributed adaptive cooperative time-varying formation tracking guidance problems of multiple aerial vehicles system against a maneuvering target are investigated. Different from the former results, the proposed cooperative guidance strategies are based on distributed time-varying formation tracking theories. Firstly, the leader aerial vehicle is designed to achieve interception with desired terminal attack angle, which provides a reference trajectory. The uncertain dynamic items and target's uncertain maneuver have been compensated. For the follower aerial vehicles, the distributed cooperative time-varying formation tracking guidance laws are raised. Adaptive distributed extended state observers are introduced to estimate the leader vehicle's states and input information. Then, an algorithm is shown for determining guidance parameters of cooperative guidance laws. Thirdly, the properties and the stabilities of the algorithm are discussed in detail. Finally, a simulation experiment is performed for showing the feasibility and effectiveness of achieved results.

Four hydrogen bond acceptors (HBAs) with different carbon chain length substituents, including methyl-triphenyl phosphonium bromide (MTPB), ethyl-triphenyl phosphonium bromide (ETPB), propyl-triphenyl phosphonium bromide (PTPB), and butyl-triphenyl phosphonium bromide (BTPB), combined with ethylene glycol (EG) were developed to synthesize four low-viscosity deep eutectic solvents (DESs). In this study, the effect of different substituents in DESs on low-concentration SO2 absorption was systematically studied at 30–70 °C. Experimental results show that the EG-MTPB DES has a higher SO2 absorption capacity and a lower viscosity than other DESs. The reason for the higher SO2 absorption capacity of EG-MTPB DES was described by viscosity experiments and quantum chemical calculations. It was shown that the strong polarization ability of the CH3 group promotes the absorption of SO2 by DESs. 1H NMR and FTIR results indicated that chemical interactions primarily exist between the S of SO2 and Br, and the O of SO2 and the H atom of EG form hydrogen bonds. The density functional theory (DFT) results also confirm that the charge of the Br atom migrated to the S atom. Also, thermostability and regeneration experiments showed that the EG-MTPB DES exhibits good stability and can thus be used for industrial flue gas desulfurization.

Attempts were made to construct the molecular structures of vitrinite samples from four bituminous with different ranks and to investigate the correlation of molecular structures to thermoplastic properties of vitrinite by using a number of advanced analytical techniques combined with theoretical methods. The Gieseler plastometry and caking index showed that the Ewirgol vitrinite had a high fluidity (MF = 17675 ppm), wide plastic range (ΔT = 105.1 °C) and good caking properties (G = 99.32). Various analytical technique, e.g. Solid-state 13C nuclear magnetic resonance spectroscopy, Fourier transform infrared spectroscopy, X-ray diffraction analysis and Raman spectroscopy, provided comprehensive structural information for establishing molecular models of vitrinite samples with Density Functional Theory. These molecular models showed that the Ewirgol vitrinite had more cyclic aliphatic structures that contribute significantly to the fluidity development and caking properties. These cyclic aliphatic structures could be precursors of the aromatic rings in liquid molecules during coking and provide transferable hydrogens that saturate the free radicals in the thermoplastic range. The cyclic aliphatic structures may facilitate the formation of such molecular structures with an appropriate molecule size that maintains the mobile phase in the thermoplastic range to develop fluidity.

To better understand the role of microwave and the mechanisms of thermal cracking and catalytic reforming of lignocellulosic bio-oils, this study compares the difference in the reaction characteristics between microwave-assisted and conventional heating of representative bio-oil model compounds. Syringol and guaiacol were selected as bio-oil model compounds. The effects of the heating method on the conversion of the model compound and the yield and composition of products were systematically investigated in the temperature range of 600–700 °C. The results showed that high reaction temperature and microwave-assisted heating favoured the conversion of model compounds, and the conversions of syringol were generally higher than those of guaiacol under the same conditions (temperature, heating method). The heating method was found to greatly influence the yield and composition of products. The bio-oil obtained from conventional thermal cracking of model compounds contained phenolics, aromatic hydrocarbons, aryl alkyl ethers, and oxygen-containing heterocyclic compounds. In contrast, microwave-induced polarisation of poorly stable methoxy groups promotes the formation of phenolics, the concentration of the phenolic in the guaiacol and syringol bio-oil reached 62.5–66.17 area% and 85.18–87.65 area%, respectively, in the temperature range of 600–700 °C. Catalytic reforming of model compounds showed that activated carbon catalyst drastically promoted the phenol formation, particularly under microwave-assisted heating, the phenol concentration reached 93.9–97.97 area% in bio-oil during catalytic reforming of guaiacol. The formation of electron-hole pairs on the active metal sites induced by microwave radiation possibly enhanced the demethoxylation to selectively generate phenol due to the strong electron-donating ability of the methoxyl group. Microwave-assisted catalytic reforming of the model compounds was also beneficial for H2 formation because of the direct dehydrogenation of methyl radicals and the gas-phase reactions. The H2 concentrations of 81.07–82.41 vol.% and 75.2–79.16 vol.% were obtained during microwave-assisted catalytic reforming of guaiacol and syringol, respectively.

Graphene composite materials have attracted significant attention for green energy storage systems due to their excellent electrochemical properties. We report a low-cost and environmentally friendly approach for synthesis of 3D multilayer graphene nanostructures (3DMGS) via catalytic graphitization and chemical oxidation-thermal reduction using biomass-based activated carbon (AC) as a precursor. The combination of microwave catalytic graphitization and chemical oxidation results in an active material with a unique physical and chemical structure. 3DMGS possesses a high specific surface area (503 m2 g−1) and an interconnected hierarchical porous structure with many defects and edges, which provide sufficient lithium-ion diffusion sites and facilitate fast ion transportation. When used as anode material for Li-ion batteries, 3DMGS exhibit outstanding rate capability and cycling stability (260 mAhg−1 at 5000 mAg−1 after 1100 cycles with charge retention of 114.47%.) and ultrahigh specific capacity (1513 mAhg−1 at 100 mAg−1).

An accurate description of homogeneous ice nucleation (HIN) rate strongly relies on the availability of data of ice-water interface energy and activation energy when water molecules cross the ice-water interface. However, it proves extremely challenging to experimentally measure the values of these two quantities for the supercooled water. In this study, a theoretical model based on the molecular kinetic energy distribution is presented, thus avoiding the need to specifying the above two parameters. The predicted HIN temperatures under different pressures agree with the experimental data with deviations less than 3%. Nonlinear variations of ice germ size and concentration were found, which suggests it might be erroneous to utilise the data obtained under high temperatures to linearly extrapolate water characteristics in low-temperature regions. Significant improvements in model prediction accuracy were achieved after the inclusions of temperature fluctuation and droplet internal high pressure. The presentmodel proves capable of accurately predicting the HIN rate over temperatures down to 190 K.

Arsenic is extremely toxic and its release has caused great environmental concerns. Coal combustion is considered to be one of the major anthropogenic emission sources. Arsenic removal technology from coal combustion can be divided into three categories: pre-combustion removal, removal during combustion and post-combustion removal. The post-combustion removal is also called removal from flue gas, which includes several technological developments, namely, the removal using existing air pollutant control devices (APCDs), adsorption, traditional oxidation and advanced oxidation based on removal principle. This review summarizes the latest advances of these arsenic removal technologies. The performance, mechanism and characteristics of arsenic removal technologies were overviewed and analyzed. The merits and drawbacks, and the challenges and prospects of each arsenic removal technologies were discussed. It was found that pre-combustion removal, removal during combustion and removal using APCDs can achieve arsenic removal to a degree, but their removal efficiencies are usually low. Injection of adsorbent into the flue gases can achieve higher arsenic removal efficiency. Calcium-based adsorbents were found to be one of the most efficient ones for arsenic removal. Their shortcoming is the high-temperature sintering and deactivation caused by competitive adsorption of acidic gases. Other adsorbents suffer from low activity, small specific surface area, high cost, or/and little recovery. Further development of advanced adsorbents that are anti-sintering, anti-deactivation, large specific surface area, low-cost, separable, and recyclable should be the main focus in future research. Collaborative control of multiple systems such as removal during combustion, removal using APCDs or/and tail adsorption/oxidation is a promising strategy. Advanced oxidation technologies (AOTs) can achieve high arsenic removal efficiency (90–100%), recovery of arsenic resources and potential simultaneous removal of multi-pollutants, possessing good prospect.

A simple, cost-effective, and environmentally friendly route was developed to synthesize graphene nanosheets from humic acid via preliminary carbonization coupled with oxidation-exfoliation-thermal reduction. Such graphene nanosheets have a high specific surface area (495 m 2 ·g − 1 ) with large pore volume (2.987 cm 3 ·g − 1 ), unique interconnected mesoporous structure and uniform oxygen-containing functional groups in layered graphene framework, which offer a favorable and efficient pathway for the electrolyte propagation and transportation. The electrodes of supercapacitors made from these graphene nanosheets exhibit a maximum specific capacitance of 272 F·g − 1 at the current density of 50 mA·g − 1 in aqueous electrolyte, and possess excellent rate capability, low resistance, superior cycling performance with over 96.5% initial capacitance retention after 8000 cycles. The corresponding supercapacitors deliver a desirable energy density of 6.47 Wh·kg − 1 at a powder density of 2250 W·kg − 1 . This study demonstrates a promising synthesis route for large-scale production of graphene nanosheets from renewable and green humic acid for high performance supercapacitors.

Hollow carbon nanofibers (HCNFs) were found to have formed during microwave pyrolysis of palm kernel shell (PKS) at 500 and 600 °C. The formation of HCNFs was only observed during microwave pyrolysis and not the fixed-bed pyrolysis, indicating that microwave played a key role in formation of HCNFs. X-ray diffraction (XRD) analysis of microwave bio-chars showed typical carbon diffractions at 2θ = 26.3° and 43.2°, indicating good graphitic structure of HCNFs, especially for bio-chars prepared at 600 °C. High resolution transmission electron microscope (HRTEM) results revealed multiwall nature of the HCNFs with carbon layer spacing of 0.34 nm. Two major tubular and bamboo-shape structures were observed for HCNFs. With increasing microwave pyrolysis temperature from 500 to 600 °C, the yield of HCNFs increased from 5.85 wt.% to 9.88 wt.%. Raman spectroscopy analysis showed that with increasing pyrolysis temperature to 600 °C, the I D / I G ratio decreased from 0.95 to 0.86, indicating higher order of the carbon layers of the HCNFs. Energy dispersive X-ray spectroscopy (EDS) showed the presence of Fe, K, and Ca in HCNFs structure which may have played a catalytic role during their formation and growth. Mechanism of formation and growth of HCNFs under microwave irradiation were proposed and discussed. The HCNFs-coated bio-char has great potential for removal of heavy metals from waste water.

Behavior and nature of water in biomass significantly influence the thermochemical conversion processes. This study investigates the characteristics and behavior of water in lignocellulosic and microalgal biomass using differential scanning calorimetry (DSC) and low-temperature X-ray diffraction (XRD) methods. Pine sawdust (PS), peanut shell (PT), and microalgae (MA) samples with different water contents were used and analyzed systematically. Freezable free water was detected in all biomass samples through DSC analysis. Different from PS and PT, a shift in the position of freezable free water peaks was observed during freezing process of MA on DSC, which was attributed to the strong hydrophilicity of this biomass. No freezable bound water was observed in the biomass samples. However, significant amount of non-freezable bound water was detected in all biomass samples. The freezing enthalpies of freezable free water in PS, PT, and MA ranged between 319.04 and 297.7 kJ/kg which were in good agreement with that of bulk water. The boundary between freezable and non-freezable water in the biomass samples was clearly defined combining DSC and XRD analyses. The amount of non-freezable bound water in biomass samples directly correlated with the relative concentration of oxygen functional groups in biomass samples.

The oligomers having the blue photoluminescence and conductivities of 5 × 10–7–7.4 × 10–4 S m–1 after doping by iodine are extracted successfully from coal tar pitches which were dealt with by the air oxidization method at 350°C. Meanwhile, it is observed that extracted materials have the blue photoluminescence with the fluorescence quantum yield of 7–10.2%. In these cases, we used the solutions of toluene and pyridine to extract these functional materials from coal tar pitches. Consequently, we consider these extracted materials showing the advantages in the application of fabricating the electronic devices, because it can decrease the production cost remarkably than use of the materials obtained by general organic synthesis methods. Finally, this research also can provide the one of beneficial references for solving the serious problem of overproduction of coal tar pitches in China. The oligomers having the blue photoluminescence and conductivities of 5 × 10–7–7.4 × 10–4 S m–1 after doping by iodine are extracted successfully from coal tar pitches which were dealt with by the air oxidization method at 350°C. Meanwhile, it is observed that extracted materials have the blue photoluminescence with the fluorescence quantum yield of 7–10.2%. In these cases, we used the solutions of toluene and pyridine to extract these functional materials from coal tar pitches. Consequently, we consider these extracted materials showing the advantages in the application of fabricating the electronic devices, because it can decrease the production cost remarkably than use of the materials obtained by general organic synthesis methods. Finally, this research also can provide the one of beneficial references for solving the serious problem of overproduction of coal tar pitches in China.

Catalytic microwave pyrolysis of peanut shell (PT) using Fe3O4, Na2CO3, NaOH, and KOH for production of phenolic-rich bio-oil was investigated. The effects of catalyst type, pyrolysis temperature, and biomass/catalyst ratio on product distribution and composition were studied. Among four catalysts tested, Na2CO3 significantly increased the selectivity of phenolic compounds in bio-oil during microwave pyrolysis. The highest phenolics concentration of 57.36% (area) was obtained at 500 °C and PT:Na2CO3 ratio of 8: 1. The catalytic effect to produce phenolic compounds among all the catalysts tested can be summarized in the order Na2CO3>Fe3O4>KOH>NaOH. Using KOH and NaOH as catalyst resulted in formation of bio-oil with enhanced higher heating value (HHV) and lower oxygen content, indicating that these catalysts enhanced the deoxygenation of bio-oil. The scanning-electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDS) analysis of char particles showed the melting of magnetite and vaporizationcondensation of mineral salt catalysts on char particle, which was attributed to extremely high local temperatures during microwave heating.

Fly ash is a potential source of highly reactive feedstock for CO 2 mineral carbonation. It does not require pre-treatment, but it has a low carbonation rate and efficiency. To address these issues, we studied the carbonation performance and mechanism of a fly ash from Shenfu coal of China. The effects of temperature, solid to liquid ratio and gas flow rate on the carbonation efficiency of the fly ash were systematically investigated in a direct mineralisation process. Our results indicated that calcium in lime and portlandite had a higher reactivity towards CO 2 than that in other calcium bearing phases either crystalline or amorphous. Solely increasing the temperature did not improve carbonation efficiency. However, experiments in a batch reactor under elevated temperature (140, 180, and 220 °C) and pressure conditions (10 and 20 bar) using recyclable additives showed that a combination of high temperature and pressure significantly improved carbonation efficiency in the presence of 0.5 mol/L Na 2 CO 3 . Our multiple-cycle experiments showed that Na 2 CO 3 facilitated the precipitation of calcium carbonate and was well regenerated in the process.

In this study, thermogravimetric analysis coupled with Fourier transform infrared (TG-FTIR) spectroscopy was primarily used to investigate the extent of biotar cracking apparent from biomass pyrolysis and partial oxidative gasification with and without the addition of CaO. TG kinetic analysis indicated that the gasification process reaction rate increased as the the oxygen and CaO content increased. The effect of oxygen in the gasification environment was more significant for biotars cracking, in comparison to CaO addition, but resulted in higher CO and CO2 yields in the syngas. However, the presence of CaO resulted in greater catalytic conversion of tars into higher H2/CO syngas ratios at lower temperatures. In the present study, syngas with a H2/CO ratio of ∼1.5 can be achieved under conditions of a Ca/B ratio of 3 and an O2 content of 5%. Therefore, it is crucial to control both the oxygen and CaO content in the biomass gasification process in order to achieve synergetic effects related to biotar crack...