Search Results (70)

This review outlines a comprehensive methodology for the research and development of heterogeneous catalytic technologies (R&D_HeCaTe). Emphasis is placed on the fundamental interactions between reactants, solvents, and heterogeneous catalysts—specifically the roles of catalytic centers and support materials (e.g., functional groups) in modulating activation energies and stabilizing catalytic functionality. Particular attention is given to catalyst deactivation mechanisms and potential regeneration strategies. The application of molecular modeling and chemical engineering analyses, including reaction kinetics, thermal effects, and mass and heat transport phenomena, is identified as essential for R&D_HeCaTe. Reactor configuration is discussed in relation to key physicochemical parameters such as molecular diffusivity, reaction exothermicity, operating temperature and pressure, and the phase and “aggressiveness” of the reaction system. Suitable reactor types—such as suspension reactors, fixed-bed reactors, and flow microreactors—are evaluated accordingly. Economic and environmental considerations are also addressed, with a focus on the complexity of reactions, selectivity versus conversion trade-offs, catalyst disposal, and separation challenges. To illustrate the breadth and applicability of the proposed framework, representative industrial processes are discussed, including ammonia synthesis, fluid catalytic cracking, methanol production, alkyl tert-butyl ethers, and aniline. Full article

Developing and utilizing capture and storage technologies for CO₂ has become a critical research topic due to the significant greenhouse effect caused by excessive CO₂ emissions. A conventional physical absorption process for CO₂ capture is polyethylene glycol dimethyl ether (NHD); however, its limited application range is caused by its poor absorption of CO₂ at low pressures. In this work, the CO₂ absorption of NHD was enhanced by combining NHD with a novel chemical absorbent 2-methylimidazole (2-mIm)-ethylene glycol (EG) solution to improve CO₂ absorption. Viscosity and CO₂ solubility were examined in various compositions. The CO₂ solubility in the mixed solution was found to be at maximum when the mass fractions of NHD, 2-mIm, and EG were 20%, 40%, and 40%, respectively. In comparison to pure NHD, the solubility of CO₂ in this mixed solution at 30 °C and 0.5 MPa increased by 161.2%, and the desorption heat was less than 30 kJ/mol. The complex solution exhibits high selectivity and favorable regeneration performance in the short term. However, it is more sensitive to moisture content. The results of this study can provide important data to support the construction of new low-energy solvent systems and the development of novel CO₂ capture processes. Full article

In the wake of global energy transition and the “dual-carbon” goal, the rapid growth of electric vehicles has posed challenges for large-scale lithium-ion battery decommissioning. Retired batteries exhibit dual attributes of strategic resources (cobalt/lithium concentrations several times higher than natural ores) and environmental risks (heavy metal pollution, electrolyte toxicity). This paper systematically reviews pyrometallurgical and hydrometallurgical recovery technologies, identifying bottlenecks: high energy/lithium loss in pyrometallurgy, and corrosion/cost/solvent regeneration issues in hydrometallurgy. To address these, an integrated recycling process is proposed: low-temperature physical separation (liquid nitrogen embrittlement grinding + froth flotation) for cathode–anode separation, mild roasting to convert lithium into water-soluble compounds for efficient metal oxide separation, stepwise alkaline precipitation for high-purity lithium salts, and co-precipitation synthesis of spherical hydroxide precursors followed by segmented sintering to regenerate LiNi_1/3Co_1/3Mn_1/3O₂ cathodes with morphology/electrochemical performance comparable to virgin materials. This low-temperature, precision-controlled methodology effectively addresses the energy-intensive, pollutive, and inefficient limitations inherent in conventional recycling processes. By offering an engineered solution for sustainable large-scale recycling and high-value regeneration of spent ternary lithium ion batteries (LIBs), this approach proves pivotal in advancing circular economy development within the renewable energy sector. Full article

The bench-scale demonstration of the UKy-IDEA process for direct air capture (DAC) technology combines solvent-aided CO₂ capture with electrochemical regeneration (ER) through a pH swing process, enabling efficient CO₂ capture and simultaneous solvent regeneration, producing high-purity hydrogen as a valuable co-product. The system shows stable performance with over 90% CO₂ capture efficiency and approximately 80% CO₂ recovery, handling ambient air at 280 L/min. During testing, the unit captured 1 kg of CO₂ over 100 h, with a concentrated CO₂ output purity of around 70%. Operating efficiently at low voltage (<3 V), the system supports flexible and remote operation without AC/DC converters when using intermittent renewable energy. Techno-economic analysis (TEA) and Life Cycle Assessment (LCA) highlight its minimized required footprint and cost-effectiveness. Marketable hydrogen offsets capture costs, and compatibility with renewable DC power enhances appeal. Hydrogen production displacing CO₂ produced via electrolysis achieves 0.94 kg CO₂ abated per kg CO₂ captured. The project would be economic, with USD 26 per ton of CO₂ from the federal 45Q tax credit for carbon utilization, and USD 5 to USD 12 per kg for H₂. Full article

Bisphenol A is a widely recognized endocrine disruptor that persists in ecosystems, harms aquatic organisms, and contributes to ecological degradation, raising global environmental concerns. Numerous studies have explored β-cyclodextrin–based adsorbents for Bisphenol A removal; however, their regeneration remains a major challenge, often relying on energy-intensive processes and excessive use of organic solvents. In this study, Bisphenol A was selected as a model pollutant, and its adsorption onto β-cyclodextrin nanosponges was investigated. After adsorption, Bisphenol A was efficiently recovered from the saturated β-cyclodextrin nanosponges using an innovative and sustainable supercritical CO₂-based green process, which simultaneously regenerated the adsorbent. The adsorption process achieved an efficiency of 95.51 ± 0.82% under optimized conditions (C₀ = 150 mg/L, m_β-CDNS = 0.15 g, T = 25 °C, and N = 200 rpm), with a maximum adsorption capacity of 47.75 ± 0.28 mg/g. The regeneration process achieved over 99% efficiency at 60 °C and 300 bar, with 10% (v/v) ethanol as a co-solvent, nearly fully restoring the adsorbent’s performance. Unlike conventional regeneration techniques, this green approach eliminates the need for environmentally harmful organic solvents while preserving the adsorbent’s structural integrity, making it a highly efficient and sustainable alternative. This study is the first to demonstrate the effective application of supercritical CO₂-based regeneration for β-cyclodextrin nanosponges in Bisphenol A removal, providing a scalable and environmentally sustainable solution for wastewater treatment. Furthermore, characterization analyses confirmed that the adsorbent retained its chemical and morphological stability after adsorption and regeneration. Full article

The increasing concentration of carbon dioxide (CO₂) in the atmosphere is a significant contributor to global warming and climate change. Effective CO₂ capture and storage technologies are critical to mitigating these impacts. This review explores various materials used for CO₂ capture, focusing on the latest advancements and their applications. The review categorizes these materials into chemical and physical absorbents, highlighting their unique properties, advantages, and limitations. Chemical absorbents, such as amine-based solutions and hydroxides, have been widely used due to their high CO₂ absorption capacities and established technological frameworks. However, they often suffer from high energy requirements for regeneration and potential degradation over time. Recent developments in ionic liquids (ILs) and polymeric ionic liquids (PILs) offer promising alternatives, providing tunable properties and lower regeneration energy. Physical absorbents, including advanced solvents like nanofluids and ionic liquids as well as industrial processes like selexol, rectisol, and purisol, demonstrate enhanced CO₂ capture efficiency under various conditions. Additionally, adsorbents like activated carbon, zeolites, metal-organic frameworks (MOFs), carbon nanotubes (CNTs), and layered double hydroxides (LDHs) play a crucial role by providing high surface areas and selective CO₂ capture through physical or chemical interactions. This paper summarizes the state of research on different materials and discusses their advantages and limitations while being used in CO₂ capture technologies. This review also discussed multiple studies examining the use of catalysts and absorption mechanisms in combination with different sorbents, focusing on how these approaches enhance the efficiency of absorption and desorption processes. Through a comprehensive analysis, this review aims to provide valuable insights into the type of materials that are most suitable for CO₂ capture and also provides directions for future research in this area. Full article

One of the most used methods for capturing acidic gases from the atmosphere is the use of amines that react with the acids and can later be recovered. The choice of amines that are most efficient in capturing has been the subject of several studies; however, the energy effort for their regeneration is also important. While the polarity of the solvent plays a critical role in determining which amines efficiently capture CO₂, the heat capacity of the solvent is also a significant factor in the regeneration process. In this work, we present values for Reichardt’s $E_{\mathrm{T}}^{\mathrm{N}}\left(30\right)$ and Kamlet−Taft parameters, such as π* (dipolarity/polarizability), α (acidity), and β (basicity), for solutions of two alkanolamines and two alkoxyamines dissolved in propane-1,3-diol, at 298.15 K, a solvent with a lower heat capacity than water. In addition to the polarity characterization of the amines in that solvent, the aim of this study is to analyze the differences observed in the solvatochromic parameters when water is replaced by alcohol. The impact of this change on the values of those parameters for the binary amine + solvent solutions was assessed by calculating the transfer values, ${\Delta }_{\mathrm{transf}}\left(F_i,x_i\right)$. Defined as, ${\Delta }_{\mathrm{transf}}\left(F_i,x_i\right)=F_i\left(1,3\mathrm{PD}\right)-F_i\left({\mathrm{H}}_2\mathrm{O}\right)$, these transfer values represent the difference in the parameters when the amines are transferred from water to alcohol. While the water medium is more favourable in terms of π* for CO₂ capture, the alcohol medium appears to hold more promise in terms of β. Full article

In chemical absorption for carbon capture, the regeneration heat is a key factor determining solvent regeneration energy consumption, and the sterically hindered amine 2-amino-2-methyl-1-propanol (AMP) has great potential for application. In this paper, a CO₂ reaction heat measurement system designed and constructed by our team was used to perform a comparative study on AMP and monoethanolamine (MEA). Moreover, five additives—MEA, diglycolamine (DGA), diethanolamine (DEA), methyldiethanolamine (MDEA), and piperazine (PZ)—were introduced into AMP-based solutions to investigate the promotion performance of these blended solvents. The results revealed that although AMP exhibited a slower absorption rate compared to MEA, it demonstrated a higher CO₂ loading capacity and cyclic capacity, as well as a lower reaction heat, making it advantageous in terms of regeneration energy consumption. At the same total concentration, the absorption capacity of blended solutions (excluding AMP-MEA solutions) was generally lower than that of single-component AMP solutions. Among these additives, MEA and PZ could enhance the absorption rate clearly yet increase the reaction heat at the same time; DGA and DEA could decrease the overall absorption performance. Generally, AMP-MDEA solutions showed the best desorption performance, with the 15 wt% AMP + 5 wt% MDEA mixture demonstrating the lowest regeneration heat and good cyclic capacity. Full article

Lithium-ion batteries (LIBs) are an indispensable power source for electric vehicles, portable electronics, and renewable energy storage systems due to their high energy density and long cycle life. However, the exponential growth in production and usage has necessitated highly effective recycling of end-of-life LIBs to recover valuable resources and minimize the environmental impact. Pyrometallurgical and hydrometallurgical processes are the most common recycling methods but pose considerable difficulties. The energy-intensive pyrometallurgical recycling process results in the loss of critical materials such as lithium and suffers from substantial emissions and high costs. Solvent extraction, a hydrometallurgical method, offers energy-efficient recovery for lithium, cobalt, and nickel but requires hazardous chemicals and careful waste management. Direct recycling is an alternative to traditional methods as it preserves the cathode active material (CAM) structure for quicker and cheaper regeneration. It also offers environmental advantages of lower energy intensity and chemical use. Hybrid pathways, combining hydrometallurgical and direct recycling methods, provide a cost-effective, scalable solution for LIB recycling, maximizing material recovery with minimal waste and environmental risk. The success of recycling methods depends on factors such as battery chemistry, the scalability of recovery processes, and the cost-effectiveness of waste material recovery. Though pyrometallurgical and hydrometallurgical processes have secured their position in LIB recycling, research is proceeding toward newer approaches, such as direct and hybrid methods. These alternatives are more efficient both environmentally and in terms of cost with a broader perspective into the future. In this review, we describe the current state of direct recycling as an alternative to traditional pyrometallurgical and hydrometallurgical methods for recuperating these critical materials, particularly lithium. We also highlight some significant advancements that make these objectives possible. As research progresses, direct recycling and its variations hold great potential to reshape the way LIBs are recycled, providing a sustainable pathway for battery material recovery and reuse. Full article

Power plants are one of the main sources emitting the CO₂ that is responsible for climate change consequences. Post-combustion carbon capture (PCC), particularly using an aqueous solution, is highly recommended to be used as a mitigation solution to reduce the emissions of CO₂ from power plants. Although PCC is a promising solution, the process still needs further development to reduce the energy demand for solvent regeneration. This paper reviews the challenges related to the post-combustion processes and finds the correlations between selected variables addressed by several researchers. Moreover, this study provides valuable insights into the factors influencing the reduction in energy demand and efficiency penalties. The research findings highlight the importance of considering two key drivers during the design of the PCC process. These are the absorber temperature and the type and amount of the selected solvent. Indeed, statistical analyses show that there is a correlation between the identified drivers’ values and the energy demand of solvent regeneration. Full article

To further enhance the safety and energy efficiency of the Fe₃O₄ preparation experiment, we proposed a strategy for synthesizing monodisperse Fe₃O₄ microspheres through a one-step solvothermal process. In this environmentally friendly synthesis method, stable FeCl₃∙6H₂O was utilized as the sole raw material, while ethylene glycol, characterized by its high boiling point and favorable safety profile, served as the solvent. Additionally, inexpensive and readily available urea was selected to function either as a mineralizer or surfactant. Through this one-step solvothermal reaction, the target product of Fe₃O₄ could be obtained without subsequent calcination under reducing or inert atmospheres, thereby enhancing experimental safety and promoting energy conservation. By controlling the amount of urea added, it became feasible to produce monodisperse magnetic Fe₃O₄ microspheres characterized by complete crystallinity and high yield. Utilizing the as-synthesized Fe₃O₄ as a catalyst, we investigated its photocatalytic activity against xylenol orange organic dyes along with its regeneration characteristics. When 40 mmol of urea was incorporated into the reaction mixture, the resulting Fe₃O₄ sample exhibited optimal photocatalytic performance; a 20 mg/L xylenol orange solution became colorless and transparent after just 1.5 h of UV light irradiation. Furthermore, during five consecutive regeneration cycles, its catalytic activity could be restored to its initial level. Importantly, Fe₃O₄ demonstrated excellent magnetic sensitivity properties that facilitated rapid targeted separation under an external magnetic field, providing convenience for recovery and collection purposes. Full article

In this study, a process for the simultaneous production of hydrogen and carbon from waste organic solvents using liquid plasma was investigated. Ferrite-based perovskites were introduced as catalysts to evaluate the productivity of hydrogen and carbon. A novel ferrite-based perovskite composite, Pr_xNi_yFeO₃, was synthesized. The waste organic solvent was converted into liquid hydrocarbons, primarily composed of toluene, through a simple distillation process. Hydrogen (>98%) and nanocarbon were produced through the liquid plasma reaction of the purified organic solvent. The ferrite-based perovskites demonstrated excellent absorption capacities for visible light. Among them, Pr_xNi_yFeO₃ exhibited the highest absorption capacities for both UV and visible light and had the smallest band gap energy (approximately 1.72 eV). In the liquid plasma decomposition of organic solvents, the ferrite-based perovskites enhanced the hydrogen production rate and carbon yield. The highest hydrogen production rate and carbon yield were achieved with the newly synthesized Pr_xNi_yFeO₃ perovskite composite. Pr_xNi_yFeO₃, which has the narrowest band gap compared to other catalysts, is highly sensitive to the strong visible light emitted from plasma and exhibits excellent catalytic activity. This catalyst also demonstrated remarkable reaction activity sustainability and the potential for recycling through regeneration. Full article

This study aims to evaluate the performance of a new hybrid solvent, comprising aqueous MDEA and tetrabutylphosphonium trifluoroacetate ([TBP][TFA]), for CO₂ capture and to optimize its CO₂ absorption efficiency. First, this study focused on predicting the thermodynamic properties of aqueous MDEAs and [TBP][TFA] and their interaction energy with CO₂ using COSMO-RS. Based on the prediction, it aligns with the principle that CO₂ solubility in the MDEA-[TBP][TFA] hybrid solvent decreases as the Henry’s Law constant increases, with the interactions primarily governed by van der Waals forces and hydrogen bonding. The aqueous MDEA-[TBP][TFA] hybrid solvent was prepared in two steps: synthesizing and blending [TBP][TFA] with aqueous MDEAs. The formation and purity of [TBP][TFA] were confirmed through NMR, FT-IR, and Karl Fischer. The heat capacity of the hybrid solvents was lower than their aqueous MDEA solutions. The performance and optimization of CO₂ capture were studied using RSM-FC-CCD design, with the optimal value obtained at 50 wt.% MDEA, 20 wt.% [TBP][TFA], 30 °C, and 30 bar (12.14 mol/kg), aligning with COSMO-RS predictions. A 26% reduction in the heat capacity was achieved with the optimal ratio (wt.%) of the hybrid solvent. These findings suggest that the aqueous MDEA-[TBP][TFA] hybrid solvent is a promising alternative for CO₂ capture, providing a high removal capacity and lower heat capacity for more efficient regeneration compared to commercial aqueous MDEA solutions. Full article

Low-carbon fuels, feedstocks, and energy sources can play a vital role in the decarbonization of clinker production in cement manufacturing. Fuel switching with renewable natural gas, green hydrogen, and biomass can provide a low-carbon energy source for the high-temperature process heat during the pyroprocessing steps of clinker production. However, up to 60% of CO₂ emissions from clinker production are attributable to process-related CO₂ emissions, which will need the simultaneous implementation of other decarbonization technologies, such as carbon capture. To evaluate the potential of fuel switching and carbon capture technologies in decarbonizing the cement industry, a study of the facility-level CO₂ emissions is necessary. This study evaluates the potential for using a single low-carbon fuel as an energy source in clinker production for cement manufacturing compared to conventional clinker production (which uses a range of fuel mixes). In addition, conventional carbon capture (operated with natural gas-based steam for solvent regeneration) and electrified carbon capture configurations were designed and assessed for net-zero emission targets. Carbon emissions reductions with and without biogenic emissions credits were analyzed to ascertain their impact on the overall carbon accounting. Results show that carbon emissions intensity of cement can vary from 571 to 784 kgCO₂eq/metric ton of cement without carbon capture and from 166.33 to 438.66 kgCO₂eq/metric ton of cement with carbon capture. We find that when biogenic carbon credits are considered, cement production with a sustainably grown biomass as fuel source coupled with conventional carbon capture can lead to a net-negative emission cement (−271 kgCO₂eq/metric ton of cement), outperforming an electrified capture design (35 kgCO₂eq/metric ton of cement). The carbon accounting for the Scope 1, 2, and biogenic emissions conducted in this study is aimed at helping researchers and industry partners in the cement and concrete sector make an informed decision on the choice of fuel and decarbonization strategy to adopt. Full article

As natural gas-fired combined cycle (NGCC) power plants continue to constitute a crucial part of the global energy landscape, their carbon dioxide (CO₂) emissions pose a significant challenge to climate goals. This paper evaluates the feasibility of implementing post-combustion carbon capture, storage, and utilization (CCSU) technologies in NGCC power plants for end-of-pipe decarbonization in Uzbekistan. This study simulates and models a 450 MW NGCC power plant block, a first-generation, technically proven solvent—MEA-based CO₂ absorption plant—and CO₂ compression and pipeline transportation to nearby oil reservoirs to evaluate the technical, economic, and environmental aspects of CCSU integration. Parametric sensitivity analysis is employed to minimize energy consumption in the regeneration process. The economic analysis evaluates the levelized cost of electricity (LCOE) on the basis of capital expenses (CAPEX) and operational expenses (OPEX). The results indicate that CCSU integration can significantly reduce CO₂ emissions by more than 1.05 million tonnes annually at a 90% capture rate, although it impacts plant efficiency, which decreases from 55.8% to 46.8% because of the significant amount of low-pressure steam extraction for solvent regeneration at 3.97 GJ/tonne CO₂ and multi-stage CO₂ compression for pipeline transportation and subsequent storage. Moreover, the CO₂ capture, compression, and transportation costs are almost 61 USD per tonne, with an equivalent LCOE increase of approximately 45% from the base case. This paper concludes that while CCSU integration offers a promising path for the decarbonization of NGCC plants in Uzbekistan in the near- and mid-term, its implementation requires massive investments due to the large scale of these plants. Full article