Institutional Repository of GuangZhou Institute of Energy Conversion, CAS
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Study on biomass and polymer catalytic co-pyrolysis product characteristics using machine learning and shapley additive explanations (SHAP)
No full textBiomass and polymer catalytic co-pyrolysis can convert waste into higher-quality fuels, thereby reducing the use of fossil fuels to some extent. However, this process is an extremely complex thermochemical conversion, influenced by numerous factors such as feedstock properties, operational variables, and catalyst. Currently, experimental methods require substantial time and resource investment. Machine learning (ML) can fit and match input and output features based on existing data, achieving extremely high accuracy in the co-pyrolysis process. This study applies advanced ML models to study the biomass and polymer catalytic co-pyrolysis process, with a focus on the yield of pyrolysis products and the variations of the oxygen-containing components in the pyrolysis oil. The best-performing model is used for feature analysis of the correlation between inputs and outputs, based on game theory SHAP analysis. The results indicate a significant negative correlation between the polymer addition ratio and the generation of oxygen-containing components during the co-pyrolysis process. The addition of catalysts promotes the generation of pyrolysis gas during co-pyrolysis but suppresses the yield of pyrolysis oil. Additionally, catalysts significantly inhibit the formation of oxygenates in the pyrolysis oil. The XGBR model shows the highest performance in predicting pyrolysis oil yield, achieving R-2 values of 0.98 during training phase and 0.91 during testing phase. The GBR model performs well in predicting the oxygenate composition of pyrolysis oil from small datasets
Metal incorporated into magnetic hybrid covalent organic framework for high selective uptake of scandium ion
No full textThe growing demand for rare-earth elements (REEs) has led to the development of sustainable methods and materials for separating and recovering these critical metals (CM). Herein, metal was incorporated into a covalent organic framework (COF) via the solvothermal method for selective capture and uptake of scandium. The incorporation of metals into hybrid magnetic COF@COF materials has not been studied for CM's selective capture or recovery. The hybrid metal incorporated (MI-COF@COF) material shows good stability, fast kinetic, excellent selectivity, high affinity, and an enhanced adsorption capacity for scandium uptake (294.1 mg g(- 1), corresponding to 99.6 % adsorption efficiency), and robust reusability. The regression coefficient of the pseudosecond-order model achieves a higher value (R-2 = 0.999) and an equilibrium capacity of 53.5 mg g(- 1) with 98.5 % adsorption efficiency within 5 min. Notably, scandium is effectively separated with an efficiency of 94.0 % from red mud-leached solution in the presence of interfering ions. Aside from scandium, incorporating other metals into hybrid materials paved the way for economically feasible metal incorporation for targeted selective capture
Simulation study of a novel approach to couple compressed CO2 energy storage with compression heat storage in aquifers
No full textThe integration of energy storage systems is essential for addressing the limitations of renewable energy generation, such as intermittency and fluctuations. This study introduces a porous media adiabatic compressed CO2 energy storage system (PM-ACCES) that combines thermal energy storage with compressed CO2 energy storage within aquifers at different depths. PM-ACCES aims to reduce the overall system complexity by eliminating the need for thermal storage systems at the ground level to store compression heat, while simultaneously integrating CO2 energy storage with sequestration. Through comprehensive numerical simulations and thermodynamic modelling, the study evaluates the performance of the PM-ACCES system under various operating conditions. The results show that, under the default conditions of this study, the average discharge power and charge power of the PM-ACCES with solar heating over 30 days are 4663.7 kW and 2342.9 kW, respectively, with a corresponding discharge capacity of 18,655 kWh and a charge capacity of 23,429 kWh. The PM-ACCES system can operate without external heat sources, achieving a discharge power of 3045.31 kW and a discharge capacity of 12,156 kWh, while attaining a higher round-trip efficiency of 51.93 %. Additionally, the study examined various factors affecting the energy storage performance of the solar-heated PM-ACCES. The findings suggest that improving wellbore thermal insulation and utilizing deeper aquifers can significantly enhance energy storage performance. However, increasing the circulation flow rate, while boosting charge and discharge power, reduces the round-trip efficiency. These findings provide a robust foundation for future optimization of CO2-based energy storage systems, offering a promising solution for integrating renewable energy into the power grid
Recent progress in thermal catalytic conversion of CO<sub>2</sub>: Insights into synergies with alkane or biomass transformations
No full textTo achieve the goals of carbon peaking and carbon neutrality, thermal catalytic reactions that convert CO2 2 into various commodity chemicals offer promising solutions. This review summarizes four prevalent types of CO2 2 thermal catalysts tailored for producing CO, alcohols, hydrocarbons, and cyclic carbonates. A comprehensive examination is provided on the mechanisms of these catalysts, including the redox mechanism and the formate mechanism for CO2 2 to CO, the CO intermediate pathway and the formate pathway from CO2 2 to methanol, as well as the Fischer-Tropsch synthesis (FTs) route and the methanol-mediated route from CO2 2 to hydrocarbons. Key emphasis is placed on the mechanism-guided design of these catalysts and the identification and engineering of their active sites to improve catalytic performance. Furthermore, recognizing the substantial requirement of H2 2 in the thermal catalytic conversion of CO2, 2 , we examine the feasibility of the co-conversion of CO2 2 and alkanes/ biomass for overcoming the thermodynamic equilibrium limit of individual conversion and elucidate the synergistic mechanisms and catalyst development strategies for the coupling reactions. Building on this knowledge, the future direction of the co-conversion of CO2 2 and alkanes/biomass is evaluated, including the rational design of novel bifunctional catalysts via the selection of active metal/metal oxides, the introduction of doping and defects, and the engineering of supports, compositions, and morphologies. This review aims to lay the foundation for an in-depth investigation into the co-conversion of CO2 2 and alkanes/biomass
Thermodynamic performance comparison of calcium looping processes for post-combustion capture: Influence of CO<sub>2</sub> enrichment routes among three heat supply methods
No full textCalcium looping process is recognized as a promising option for low-energy consumption post-combustion CO2 capture. This paper introduced three calcium looping processes with different fossil-fuel-based heat supply methods including air combustion (CaL-AC), oxy-fuel combustion (CaL-Oxy), and chemical looping combustion (CaL-CLC). The sensitivities of key parameters on system performance are investigated, and the detailed energy analysis is conducted to reveal the thermodynamic performance difference. Results show that the changes of the average CaO conversion ratio and the solids make-up ratio bring about drastic variation of energy distributions and the specific primary energy consumption for CO2 avoidance (SPECCA) in the CaL-AC process. While temperature difference of supplying heat for calcination has a significant influence on the system performance of the CaL-CLC process. Besides, eliminating air preheating leads to the increase of the SPECCA from 3.12 MJ/kg CO2 to 4.53 MJ/kg CO2 in the CaL-AC process, which is inferior than that in the CaL-Oxy process. Furthermore, the minimum CO2 enrichment work of different pathways is examined. The unit minimum enrichment work in the CaL-CLC process is 9.92 kJ/mol CO2, lower than those in the other two processes due to the avoidance of minimum enrichment work for fuel decarbonization. Through reaction coupling, the Gibbs free energy of the combustion reaction offsets the minimum work required for O2 release, thereby avoiding the minimum separation work. In post-combustion CO2 capture processes, avoiding the CO2 enrichment work requirement during fossil fuel conversion will offer another way to reduce energy consumption
Study of the rheology and flow risk of hydrate slurries containing combined anti-agglomerants: Effects of wax, water cut and continuous phase composition
No full textAs oil and gas extraction increasingly ventures into deep-sea environments, the issues surrounding the flow safety of hydrate and wax deposits have become more critical. There is an urgent need to develop environmentally friendly and adaptable hydrate anti-agglomerants, and to expand the database and knowledge base for risk management strategies to ensure optimal production safety. This study formulated combined anti-agglomerants with varying HLB values using Span 80 and Tween 80 in different ratios. Rheological experiments were conducted to investigate their synergistic anti-agglomeration performance in water-in-oil emulsions and their adaptability in environments with wax, varying water contents, and different continuous phase compositions. The results indicate that, in comparison to a single anti-agglomerant, the combined anti-agglomerants not only increases the critical time for hydrate formation but also reduces peak viscosity and stable viscosity by 23-90 % and 25-85 %, respectively. Additionally, an index for assessing the flow risk of hydrate slurries under specific conditions was proposed, which demonstrates that the combined anti-agglomerant with an HLB value of 8.6 exhibits exceptional performance across various conditions. This finding is significant for refining risk management strategies for hydrates in deep-sea oil and gas transportation processes
Effect of complex ionic liquid additives on the formation kinetics and separation efficiency of binary gas mixture hydrates
No full textRising carbon emissions worldwide have necessitated the discovery of efficient CO2 separation and capture technologies. Owing to their good CO2 selectivity, imidazolium-based ionic liquids (ILs) have been used as additives in hydrate-based gas separation (HBGS) technologies. Sodium dodecyl sulfate (SDS) can notably improve the rate of hydrate formation when used as a surfactant. However, the synergistic effect of imidazolium-based ILs and SDS remains unknown. This study aimed at investigating the synergistic effect of imidazolium-based ILs and SDS on the hydrate formation kinetics of binary gas mixtures of CO2/N2 at different temperatures. The carbon capture and storage capacity was determined, and HBGS was evaluated using pure imidazolium-based IL 1-butyl3-methylimidazolium octyl sulfate ([BMIM] [OS]) and composites of IL and SDS as additives. Compared with pure water, [BMIM] [OS] effectively promoted gas hydrate formation and increased CO2 consumption by 107.9 %. The maximum CO2 separation factor was obtained at 273.15 K, and the mixed additive significantly enhanced gas consumption by 11.1 %. X-ray diffraction and Raman spectroscopy analysis indicated that the hydrate samples were type I structural hydrates and that [BMIM] [OS] improved the mass transfer process. The results of this study provide a theoretical basis for CO2 gas separation and capture
Developing a new ethylene glycol/H2O pretreatment system to achieve efficient enzymatic hydrolysis of sugarcane bagasse cellulose and recover highly active lignin: Countercurrent extraction
No full textImproving pretreatment efficiency is a critical premise in achieving efficient biomass conversion, and obtaining high-performance natural polymers is the guarantee of high-value conversion of biomass. In this study, a new pilot-scale continuous countercurrent pretreatment reaction unit about ethylene glycol-alkali solution was designed for pretreating sugarcane bagasse in order to achieve efficient separation of the three major components of lignocellulose when expanding the scale of pretreatment, reduce lignin deposition on the fiber surface, and obtain highly active lignin and excellent enzymatic hydrolysis efficiency of cellulose. X-ray diffractometer (XRD), X-ray photoelectron spectrometer (XPS), brunauer-emmett-teller (BET) and scanning electron microscope (SEM) methods are used to analyze the structural properties of sugarcane bagasse before and after pretreatment, and high-performance liquid chromatography (HPLC) is used to analyze the monosaccharide components in the enzymatic solution. In addition, the structural properties of the recovered lignin are analyzed by gel permeation chromatography (GPC), 31P NMR and 2D-HSQC-NMR methods. The results indicate that the system can gain a high cellulose recovery of 92.99% along with a lignin removal of 95.33%, and recovered lignin has low lignin carbohydrate complexes, low condensation, and rich in phenolic hydroxyl groups for 1.95 mmol/g. Meanwhile, the countercurrent pretreatment system can effectively reduce the deposition of lignin on the cellulose surface, which is evidently superior to the non-countercurrent pretreatment and facilitates the efficiency of enzymatic saccharification of substrate, achieving a high glucose yield of 99% as well as a total sugar yield of 91.11%. The method efficiently separates biomass in a green manner, and solid residues are easily hydrolyzed, showing potential for industrial-scale production
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