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•Preparation methods of graphene-like materials from biomass were summarized.•The mechanisms and product characteristics of different methods were discussed.•Common characterization ...instruments to determine the structure were discussed.•Tailored designs of graphene-like material need further investigation.
Two-dimensional graphene materials attracted much attention worldwide because of their superior performance in electronic devices, sensors, and energy storage. However, its application is limited by high cost and insufficient production. The work to find out a simple and environmentally friendly process is highly needed. Designed pyrolysis of biomass precursors can derive graphene-like materials. This review summarizes some typical preparation processes for graphene-like materials synthesis from biomass carbonization via pyrolysis, including salt-based activation, chemical blowing, template-based confinement, coupling with hydrothermal carbonization pretreatment, post exfoliation, and some other methods. The operation of these methods and the performance of obtained graphene-like materials were closely highlighted. The scalability of the techniques and the applications of the biomass graphene-like carbon were also discussed. Some advanced characterization methods, such as SEM, TEM, AFM, Raman, and XPS to determine the graphene-like structure and graphitization degree were also discussed. In the end, some current challenges and future perspectives of the synthesis of these graphene-like materials were concluded.
A series of ReaxFF reactive molecular dynamic simulations are performed to investigate the combustion of
n
-pentane, isopentane and neopentane. The effects of temperature and the
n
-pentane-to-O
2
...ratio on the number of main radical and molecular products for the combustion of
n
-pentane are analyzed, the combustion characteristics of
n
-pentane, isopentane and neopentane are compared, and the spontaneous combustion characteristic of
n
-pentane is discussed in this work. The results indicated that the main reactions involved in the early stage of
n
-pentane, isopentane and neopentane combustion are the pyrolysis of these working fluids, and then, O
2
molecules are involved in the oxidation reactions. The content of O
2
in reaction systems has a very obvious effect on the combustion of
n
-pentane. With the increase in the O
2
content, the consumption rate of
n
-pentane is significantly accelerated, and the rate of increase in the total fragments number is also significantly increased. Neopentane burns most intensely, followed by isopentane, and finally
n
-pentane. A faster heating rate will be accompanied by more intense spontaneous combustion of
n
-pentane and more product formation, which will cause greater harm to the surrounding area. Thus, in order to reduce the possibility of damage caused by leakage combustion of flammable working fluid, the heat source temperature and open flame around the organic Rankine cycle system should be strictly controlled, and some flame retardants are recommended to be added to the working fluid to reduce the flammability while ensuring the economy of the organic Rankine cycle. This study is conducive to the safety of
n
-pentane, isopentane and neopentane used in industrial fields.
With the growing emphasis on green chemistry and the ecological environment, researchers are increasingly paying attention to greening materials through the use of carbon-based solid acids. The ...diverse characteristics of carbon-based solid acids can be produced through different preparation conditions and modification methods. This paper presents a comprehensive summary of the current research progress on carbon-based solid acids, encompassing common carbonization methods, such as one-step, two-step, hydrothermal, and template methods. The composition of carbon source material may be the main factor affecting its carbonization method and carbonization temperature. Additionally, acidification types including sulfonating agent, phosphoric acid, heteropoly acid, and nitric acid are explored. Furthermore, the functions of carbon-based solid acids in esterification, hydrolysis, condensation, and alkylation are thoroughly analyzed. This study concludes by addressing the existing drawbacks and outlining potential future development prospects for carbon-based solid acids in the context of their important role in sustainable chemistry and environmental preservation.
A series of ReaxFF-MD simulations are employed to illuminate the oxidation mechanism of HFO-1336mzz(Z) as an environmentally friendly refrigerant in O2/H2O environment. The results showed that H2O ...molecule has a significant impact on the HFO-1336mzz(Z) oxidation reactions and promotes the rate of HFO-1336mzz(Z) oxidation decomposition. H2O molecule can react with H and O radicals to form OH radical and will provide more H atoms to combine with F radicals to generate HF molecule. The OH radical plays a crucial role in the HFO-1336mzz(Z) oxidation reactions because the reactivity of OH radical. CO2, COF2 and HF are dominant products and the other radicals COF, O, F, CF3 and CO2F have a significant impact on the HFO-1336mzz(Z) oxidation reactions. The chemical equations of HFO-1336mzz(Z) oxidation in different conditions are presented to expound the comprehensive oxidation mechanism.
•Oxidation decomposition mechanism of HFO-1336mzz(Z) are investigated by ReaxFF-MD.•The effect of temperature and H2O molecule number on the products are discussed.•HF, COF2 and CO2 are the main products.•The chemical equations of HFO-1336mzz(Z) oxidation decomposition are discussed.
•Economic-environmental-sustainable analysis was performed for subcritical ORC system.•A double-layer optimization design framework is proposed for fluid selection in ORC.•Multi-objective ...optimization results of ORC system were studied and compared.•Optimal fluid selection scheme was obtained based on different geothermal temperatures.
Global issues such as the energy crisis and environmental pollution impulse the development of waste heat recovery technologies. Organic Rankine cycle (ORC) systems are a promising solution to utilize renewable energies and recover waste heat. However, the different heat source temperatures often force the ORC to use different working fluids. Matching the heat source temperatures with suitable fluids is important to enhance the system performance and promote the marketability of this technology. In this work, a double-layer multi-objective optimization framework is proposed for subcritical ORC systems applied in the geothermal field. Four kinds of objective functions are selected in the optimization model, including net power output, total product unit cost, greenhouse gas emissions, and ecological life cycle cost to characterize system thermodynamic, exergoeconomic, environmental, and sustainable performances, respectively. The feature of the established model allows simultaneous system comprehensive design and fluid screening under specific geothermal temperatures. Results showed that the impacts of decision variables, including evaporation pressure and condensation temperature, on system performances were different under the different performance indicators. According to the balanced weighting factor case study, it is found that R134a had excellent thermodynamic and sustainable performances while R600a performed better from economic and environmental aspects at 393.15 K geothermal temperature. In addition, it was observed that the obtained optimal point shifted regularly on the Pareto curve with the change of geothermal temperature and weighting factor. Finally, under different weighting factor schemes, the optimal plans of fluid selection were obtained at certain geothermal temperatures. HCs fluids showed superior overall performance in the double-layer optimization framework considering ecological impacts, while R152a exhibited excellent comprehensive performance among the selected safe fluids under the premise of strict consideration of system security.
Ocean thermal energy is a stable and abundant marine renewable energy that can be adopted for sustainable desalination in remote islands. However, its relatively low available temperature difference ...restricts its application. Therefore, to manipulate ocean thermal energy while overcoming its unique small thermocline temperature gradient, a dual-energy-driven distillation desalination system driven by solar and ocean thermal energy is put forward. The merits of this system include resolving the nightly failure of solar desalination systems and higher productivity. To quantify the system potential, a numerical model is developed and thermodynamic analysis is conducted. A comparison between dual-energy-driven system and single-energy-driven systems is conducted. The results indicate that the yield can be significantly improved by simultaneously using solar and ocean thermal energy. A single ocean thermal energy-driven desalination can achieve the minimum freshwater productivity of 0.07 kg·h−1, while coupled solar thermal energy can improve freshwater yield to 1.21 kg·h−1, which is 30.1 % higher than that of a single solar desalination. The system power consumption is only 1.77 kW·h/ton. Furthermore, based on the actual meteorological data in Haikou, China, an annual freshwater productivity of 3524 kg (for a 1 m2 absorber plate area) can be obtained, corresponding to a gain output ratio of 0.44.
•A thermal desalination system driven by solar and ocean thermal energy is proposed.•A comprehensive mathematical model of desalination system is developed and verified.•Distillate yield and gain output ratio are examined and analyzed to assess the system.•The yield can be increased by 30.1 % via combining solar and ocean thermal energy.•Annual freshwater yield of the system is up to 3524 kg in low-latitude areas.
•The pyrolysis mechanisms of hydrocarbons are investigated using ReaxFF molecular dynamics and DFT methods.•The initiation reactions and chain reactions of pyrolysis are detailed analyzed.•The ...effects of pressure, temperature and molecular structure are considered in the thermal decomposition of hydrocarbons.•The kinetic analysis of n-pentane, isopentane, neopentane and cyclopentane pyrolysis has been carried out.
In order to investigate the decomposition mechanism of hydrocarbons, pyrolysis processes of 11 typical hydrocarbons (isobutane, isopentane, isohexane, n-butane, n-pentane, n-hexane, cyclobutane, cyclopentane, cyclohexane, benzene and toluene) are performed by using ReaxFF MD and DFT method. The results show that the initial pyrolysis reactions of these hydrocarbons can be divided into two types: homolytic cleavage of C–H bond and C–C bond. The bond dissociation energies of C–H bonds are higher than that of C–C bonds in these hydrocarbons except for toluene. The thermal decomposition rates of branched-chain hydrocarbons are faster than that of straight-chain hydrocarbons. The thermal decomposition rates of chain hydrocarbons gradually increase with the increases of C atom number. The main product molecules of hydrocarbon pyrolysis are H2, CH4, C2H2 and C2H4. The apparent activation energies of 4 hydrocarbons (n-pentane, isohexane, neopentane and cyclopentane) pyrolysis are calculated by the kinetic analysis. In further reactions, CH3, C2H5 and H radicals are collided with hydrocarbons to undergo H-abstraction reactions. The energy barriers of H-abstraction reactions are calculated by DFT.
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