Search Results (751)

Sustainable materials engineering necessitates the valorization of industrial by-products, such as coal fly ash, into functional, high-performance materials. This research addresses a core challenge in materials synthesis: establishing a deterministic technology for controlled porous structure formation to optimize the thermophysical properties of lightweight thermal insulation composites. The primary objective was to investigate the structural evolution kinetics during the high-intensity thermal processing of fly ash-based precursors to facilitate precise property regulation. We developed a novel, integrated process, underpinned by mathematical modeling of simultaneous bloating and non-equilibrium heat transfer, to evaluate key operational parameters within a vortex-layer reactor (VLR). This framework enables the a priori prediction of structural outcomes. The synthesized composite granules were subjected to comprehensive characterization, quantifying apparent density, total porosity, static compressive strength, and effective thermal conductivity. The developed models and VLR technology successfully identified critical thermal exposure windows and heat flux intensities of the heating medium required for the reproducible regulation of the composite’s porous architecture. This precise structure process control yielded materials exhibiting an optimal balance between low density (<400 kg/m³) and adequate mechanical integrity (>1.0 MPa). This work validates a scalable, energy-efficient production technology for fly ash-derived porous media. The established capability for predictive control over microstructural development provides a robust engineering solution for producing porous materials, significantly contributing to waste reduction and sustainable building practices. Full article

In this study, a three-dimensional computational fluid dynamic (CFD) model was constructed and validated against experimental data. The oxygen injection methods—specifically the primary air flow and secondary air flow—were investigated. The results demonstrate that primary air flow is the dominant factor in combustion. An increase of primary air from an φ of 0.20 to 0.75 lead to a rise in combustion peak temperature from 892.17 K to 1321.02 K, while simultaneously expending the flame combustion zone and enhancing the conversion of C₁₀H₈ and CH₄. Conversely, increasing the secondary air flow from 1 L/min to 7 L/min reduced the centrally measured temperatures form 886.09 K to 856.07 K due to irregular flow patterns, which expanded the central low-temperature region. While secondary air flow promoted more uniform reactant conversion and slightly suppressed intermediate products (e.g., soot, C₆H₆), its overall effect was secondary to that of the primary air. This research reveals a critical design insight: using primary air injection to introduce oxygen into the reactor is a reasonable approach. The findings provide valuable guidance for optimizing partial oxidation burner design and operating conditions to maximize tar conversion while maintaining reactor integrity. The study also establishes a rigorously validated CFD framework for analyzing complex reacting flows in tar thermochemical conversion reactors. Full article

Background: The conversion of carbon dioxide (CO₂) into valuable products like carbon monoxide (CO) is an important process facing limitations due to poor energy efficiency. Dielectric barrier discharge (DBD) plasma reactors offer a potential solution through synergistic plasma catalysis, making the selection of an optimal solid packing material a critical design challenge. Methods: This study investigated the impact of four different packing materials—Al₂O₃, ZrO₂, glass beads, and kaolin pellets—on the CO₂ conversion process in a DBD reactor. The materials’ physical and chemical properties (porosity and composition) were analyzed. Experiments were conducted to examine the influence of gas flow rates and bead size on CO₂ and CO concentrations. The study utilized optical emission spectroscopy (OES) and kinetic mathematical modeling to characterize the discharge and the reaction. Results: Higher gas flow rates led to a decrease in CO₂ conversion due to reduced specific energy input. The addition of solid packing significantly improved system efficiency by promoting filamentary and surface discharges, with smaller beads yielding higher conversion rates. Notably, kaolin demonstrated unique performance characteristics, suggested by its increased plasma brightness, likely due to flow-induced turbulence promoting the reaction. Conclusions: Proper material selection and packing design are crucial for efficient CO₂ splitting, concurrently boosting energy efficiency and maintaining high conversion. While Al₂O₃ (corundum) shows high intrinsic activity, kaolin emerges as a highly competitive and advantageous material when associated costs are considered paramount for large-scale applications. Full article

Simultaneous catalytic elimination of nitrogen oxides (NO_x) and volatile organic compounds (VOCs) represents a promising technology for addressing the synergistic pollution of fine particulate matters of <2.5 μm diameter (PM_2.5) and O₃. Nevertheless, it has been maintaining significant challenges in practical implementation, particularly the inherent mismatch in temperature windows between NO_x reduction and VOCs oxidation pathways, coupled with catalyst poisoning and deactivation phenomena. These limitations have hindered the industrial application of bifunctional catalysts for the removal of concurrent pollutant. This review systematically explored the fundamental mechanisms and functional roles of active sites in controlling synchronous catalytic processes. The mechanism of catalyst deactivation caused by multiple toxic substances has been comprehensively analyzed, including sulfur dioxide (SO₂), water vapor (H₂O), chlorine-containing species (Cl*), reaction by-products, and heavy metal contaminants. Furthermore, we critically evaluated the strategies of doping regulation, nanostructure engineering and morphology optimization to enhance the performance and toxicity resistance of catalysts. Meanwhile, emerging regeneration techniques and reactor design optimizations are discussed as potential solutions to improve the durability of catalysts. Based on the above critical aspects, this review aims to provide insights and guidelines for developing robust catalytic systems capable of controlling multi-pollutants in practical applications, and to offer theoretical guidance and technical solutions to bridge the gap between laboratory research and industrial environmental governance applications. Full article

Biogas and biomethane represent promising domestic fuels compatible with decarbonization targets at a time when diversification of gas sources is essential due to market volatility and increasing security risks. In laboratory practice, however, biogas production is still frequently assessed manually, which increases measurement uncertainty, limits temporal resolution, and reduces comparability between experimental series. We present an open and low-cost platform for continuous monitoring based on the hydrostatic water-displacement principle, complemented by stabilized process conditions (temperature control at 37 °C with short-term variability of approximately ±0.02 °C), continuous measurement with a 1 Hz sampling rate, and cloud-based data visualization. The methodology builds on a standardized procedure grounded in well-defined pressure–height–volume conversion relationships and transparent signal processing, enabling objective comparison of substrates and experimental setups. Validation experiments confirmed the system’s capability to capture short-term transient phenomena, improve reproducibility among parallel reactors, and maintain long-term measurement stability. Long-duration tests demonstrated short-term scatter of approximately 0.06 mL, minimal drift below 0.15% per 24 h, and an expanded uncertainty of roughly 3.1% at 100 mL. In parallel BMP tests, the continuous method yielded final volumes 5.78% higher than the discrete pressure method, reflecting systematic bias introduced by sparse manual sampling and reactor handling. The basic configuration quantifies the cumulative volume and production rate of biogas and is readily extendable to online gas composition analysis. The proposed solution offers a replicable tool for research and education, reduces costs, supports measurement standardization, and accelerates the optimization and subsequent scale-up of biogas technologies toward pilot-scale and industrial applications. Full article

Silver nanoplates hold significant promise for advanced electronic materials, especially in low-temperature conductive silver pastes crucial for next-generation solar cells. However, their widespread practical application, like many nanomaterials, is currently limited by insufficient production capacity and inconsistent quality inherent in conventional batch synthesis methods. To overcome these critical challenges, we developed a novel ultrasound-assisted continuous-flow synthesis method for the scalable and high-yield production of silver nanoplates. This innovative approach effectively addresses common issues such as nanoparticle deposition and pipeline clogging by leveraging ultrasonic cavitation for enhanced mixing and stable flow. Through systematic optimization of synthetic parameters-including temperature, flow rate, and seed concentration-our continuous-flow reactor achieved mass production of pure silver nanoplates at a rate of 3.8 g/h. This scaled-up system is capable of producing hundreds of grams per day. The as-prepared nanoplates demonstrate excellent electrical performance, highlighting the method’s potential for industrial-scale manufacturing and significantly advancing the development of high-efficiency electronic devices. Full article

Polymethoxy butyl ether (BTPOM_n), a novel diesel additive developed for suppressing incomplete combustion emissions, was synthesized via an optimized batch slurry method employing n-butanol and trioxane (TOX) over NKC-9 acid cation-exchange resin (90–110 °C). A comprehensive kinetic model elucidated the reaction mechanism, addressing competitive pathways governing both main product formation and key side reactions—specifically polyoxymethylene hemiformals (HD_n) and polyoxymethylene glycols (MG) generation. As the first detailed kinetic investigation of BTPOM_n synthesis, this work provides a fundamental dataset and a robust predictive model that are crucial for process intensification and reactor design. Hybrid optimization integrating genetic algorithms with nonlinear least-squares regression achieved robust parameter estimation, with model predictions showing excellent agreement with experimental data. Thermal effects significantly influenced reaction rates, enhancing decomposition and propagation processes with increasing temperature. Optimal catalyst loading was identified at 3 and 6 wt.%, balancing reaction acceleration and byproduct suppression. Temperature-dependent equilibrium revealed chain length regulation through growth and depolymerization processes. This mechanistic understanding enables predictive reactor design for cleaner fuel additive synthesis. It provides critical insights for developing emission-control technologies in diesel engine systems. Full article

The methanol-to-olefins (MTO) process offers a viable alternative to traditional naphtha cracking for producing light olefins, providing flexibility in feedstock sources and the potential for reduced energy consumption. This study presents a detailed plant-wide design of an MTO process, developed and optimized to increase ethylene and propylene yields while reducing energy consumption. The methodology includes comprehensive reactor modeling of a fast fluidized-bed reactor–regenerator system, accounting for coke formation kinetics, along with rigorous process simulation for the subsequent separation and purification of products. A six-column distillation train has been designed and optimized for the recovery of polymer-grade ethylene and propylene, while dual-stage CO₂ absorption units ensure complete removal of carbon dioxide. Pinch analysis is used to identify opportunities for heat integration, resulting in an optimized heat-exchanger network that significantly reduces the need for external heating and cooling utilities. The results show that the optimized MTO design achieves a methanol conversion rate of over 99.9% and produces a propylene-rich product stream with a propylene-to-ethylene ratio of approximately 1.8, while maintaining a high purity level exceeding 99.5%. By implementing heat integration and recycling by-products, including using off-gas methane as furnace fuel and repurposing waste heat for steam generation, the plant reduces utility requirements by more than 85%, significantly improving energy efficiency. An economic evaluation shows a favorable payback period of approximately 5.4 years and an internal rate of return of 15–16%, confirming the viability and industrial potential of the integrated MTO process for sustainable olefin production. Full article

A numerical model was developed to simulate a fluidized bed reactor for isobutane dehydrogenation. First, we constructed a hydrodynamic model of catalyst particle fluidization and a kinetic model for three chemical reactions in a simple lab-scale reactor (H = 70 cm, D = 2.8 cm). Experimental studies and numerical simulation of the laboratory reactor were carried out at four temperatures: 550, 575, 600, and 625 °C. The product yield results from the computational fluid dynamics simulation show a close match to the experimental data. The optimal process temperature in the laboratory reactor is 575 °C, at which the isobutylene yield is ~46.03 wt%. With decreasing temperature, the isobutylene yield decreases, and it rises as temperature increases. However, with rising temperature, the total yield of by-products increases on average to 20 wt%. We compared the CFD simulation results for two laboratory reactor models: a 3D model and a 2D axisymmetric model. For gas phase fractions, absolute deviations ranged from 0.01 to 1.12%, while relative deviations were between 0.006% and 0.114%. However, there are differences in the solid-phase particle dynamics. Second, we applied the constructed CFD model to simulate an industrial-scale reactor (H = 23.81 m, D = 4.6 m). In addition to its size, the industrial reactor differs from the laboratory reactor in its heating principle. In this configuration, the gas, preheated to 550 °C, and the catalyst particles, at 650 °C, are fed into the entire volume. The objective of this study is to test the performance of the model, which was verified on a laboratory reactor, for simulating an industrial reactor. Temperature fields and zones of reaction product formation are analyzed. The average isobutylene yield is ~31.88 wt%, which is consistent with the operation of real reactors but lower than the results for the laboratory reactor at all temperatures. The industrial reactor is more challenging to heat uniformly. It contains many internal elements that affect the movement of the gas–solid system. Overall, the model developed for the laboratory reactor has proven to be suitable for CFD modeling of an industrial reactor. Full article

This work presents a preliminary “Strengths, Weaknesses, Opportunities, and Threats” (SWOT) analysis followed by a “Correct, Adapt, Maintain, and Explore” (CAME) analysis on wood sawdust biofuel. New designs of sawdust biofuels boilers and reactors require gathering relevant information on the main characteristics of sawdust biofuels. Optimisation algorithms require not only the numerical parameters needed to find optimal solutions but also the consideration of scenarios related to the use of this type of biofuel. This work provides complementary information to create a comprehensive framework for assessing the viability and sustainability of integrating wood sawdust into diverse energy production systems. This includes an examination of the current state of sawdust utilisation, its environmental implications, and the potential of valorising this abundant biomass resource. This review further delves into the technical aspects of converting sawdust into biofuel pellets, examining various technical processes involved in its physical analysis. The intended audience of this review encompasses researchers, mechanical designers, policymakers, and industry strategists and stakeholders interested in sustainable energy solutions and waste management strategies, providing a holistic perspective on the opportunities presented by wood sawdust as a renewable energy source. Full article

Plastic pollution, driven by the durability and widespread use of polyolefins such as polypropylene (PP) and high-density polyethylene (HDPE), poses a formidable environmental challenge. To address this issue, we have developed an integrated multiscale framework that combines thermocatalytic experimentation, process-scale simulation, and molecular-level modeling to optimize the catalytic pyrolysis of PP and HDPE waste. Under the identified optimal conditions (300 °C, 10 wt % HMOR zeolite), liquid-oil yields of 60.8% for PP and 87.3% for HDPE were achieved, accompanied by high energy densities (44.2 MJ/kg, RON 97.5 for PP; 43.7 MJ/kg, RON 115.2 for HDPE). These values significantly surpass those typically reported for uncatalyzed pyrolysis, demonstrating the efficacy of HMOR in directing product selectivity toward valuable liquids. Above 400 °C, the process undergoes a pronounced shift toward gas generation, with gas fractions exceeding 50 wt % by 441 °C, underscoring the critical influence of temperature on product distribution. Gas-phase analysis revealed that PP-derived syngas contains primarily methane (20%) and ethylene (19.5%), whereas HDPE-derived gas features propylene (1.9%) and hydrogen (1.5%), highlighting intrinsic differences in bond-scission pathways governed by polymer architectures. Aspen Plus process simulations, calibrated against experimental data, reliably predict product distributions with deviations below 20%, offering a rapid, cost-effective tool for reactor design and scale-up. Complementary density functional theory (DFT) calculations elucidate the temperature-dependent energetics of C–C bond cleavage and radical formation, revealing that system entropy increases sharply at 500–550 °C, favoring the generation of both liquid and gaseous intermediates. By directly correlating catalyst acidity, molecular reaction mechanisms, and process-scale performance, this study fills a critical gap in plastic-waste valorization research. The resulting predictive platform enables rational design of catalysts and operating conditions for circular economy applications, paving the way for scalable, efficient recovery of fuels and chemicals from mixed polyolefin waste. Full article

The increasing atmospheric CO₂ concentration is one of the major environmental challenges, necessitating not only emission reduction but also effective carbon utilization. Non-thermal plasma-catalytic CO₂ conversion offers an efficient pathway under mild conditions by synergistically combining plasma activation with catalytic surface reactions. In this study, mesoporous ceria catalysts were synthesized by different methods and characterized using N₂ adsorption–desorption, SEM, XRD, XPS, CO₂-TPD, and XRF techniques. The materials exhibited distinct textural and electronic properties, including variations in surface area, pore structure, and basicity. Plasma-catalytic CO₂ dissociation experiments were conducted in a dielectric barrier discharge reactor at near-room temperature. Among the synthesized catalysts, Ce(mp)-4 demonstrated the highest CO₂ conversion of 32.3% at a 5 kV input voltage and superior energy efficiency, which can be attributed to its meso-macroporous structure that promotes microdischarge formation and enhances CO₂ adsorption–desorption dynamics. CO was the only product obtained, with near-100% selectivity. Catalyst stability testing showed no deactivation while spent catalyst characterization indicated carbon-containing species. The findings in this study highlight the critical role of tailored pore structure and basic-site distribution in optimizing plasma-catalytic CO₂ dissociation performance, offering a promising strategy for energy-efficient CO₂ utilization. Full article

This study addresses developing systematic guidelines for the design of concentration control in the oxidation of benzene to maleic anhydride within a tubular reactor. The influence of step size selection and temperature sensor location on the tuning and performance of a PI/P cascade control system applied to the oxidation process was evaluated. The reactor’s dynamic behavior was analyzed using numerical simulations based on the solution of the Fortran mathematical model. Sensor positions and multiple step sizes (from +10% to −10%) were analyzed to characterize reactor dynamics and optimize control parameters. The results show that a controller design corresponding to a −9% step in the jacket temperature offered the best performance, ensuring process stability and selectivity. In contrast, step changes between +10% and −8% caused temperature deviations beyond safe limits. Since maleic anhydride is an essential precursor in the production of resins, plastics, lubricants, and pharmaceutical intermediates, optimizing the efficiency and safety of its production represents a significant benefit to the global chemical industry. Full article

As attention to environmental risks from the PAHs in biochar production increases, developing a low-cost and easy-to-operate optimized pyrolysis process is urgent. The effect of extra biochar was investigated in order to minimize polycyclic aromatic hydrocarbons (PAHs) on biochar and residual tar for the development of a new fixed-bed pyrolysis process. Hence, the effect of extra biochar as a catalyst on the reduction effect on PAHs originating from corn stover pyrolysis was inspected and explored in this study. Pyrolysis was conducted at 500, 600, and 700 °C in a tube furnace reactor with corn stover as the biomass feedstock. Biochar prepared at 500 °C, 600 °C, and 700 °C was used as a catalyst by stacking extra biochar on top of the corn stover raw material. Then, the concentration of PAHs in corn stover biochar and residual tar inside the reactor was examined. The physicochemical characteristics, including morphology, pore structure, and chemical structures of extra biochar, were investigated separately. The results showed that, with stacking extra biochar, the concentrations of PAHs in corn stover biochar (7.15 mg/kg to 1.25 mg/kg) and residual tar (132.23 mg/kg to 101.10 mg/kg) inside the reactor decreased significantly at medium temperatures (500 °C). The concentrations of PAHs in corn stover biochar decreased from 9.14 mg/kg, 10.44 mg/kg to 3.66 mg/kg, 2.7 mg/kg. However, the concentrations of PAHs of residual tar inside the reactor increased significantly at medium temperatures (600 °C, 700 °C). In addition, the reaction mechanism of extra biochar as a catalyst to reduce PAHs in corn stover biochar was established. The results suggest that the measure of adding extra biochar reduced PAHs in resulting biochar effectively, but is not high enough to eliminate PAHs issues in the entire pyrolysis process completely. Full article

This study presents the design and simulation of an integrated pathway to produce Biodimethyl ether (Bio-DME) from biomethane derived from Agave sisalana residues, focusing on the downstream sections such as: (i) steam reforming of biogas and water-gas shift to generate syngas and (ii) indirect methanol synthesis followed by methanol dehydration to Bio-DME, including separation and recycle steps. The modeled scope excludes the anaerobic digestion stage. Benchmarking against the literature was used to validate model fidelity. The simulation delivered a single-pass methanol conversion of 81.8%, a Bio-DME reactor conversion of 44.6 mol%, and a Bio-DME yield/selectivity of ≈99 mol%; product purities reached ≈99.99 mol% Bio-DME at the first distillation column and ≈99.9 mol% MeOH in the recycle, indicating efficient separation. Compared to the literature, Bio-DME conversion in this study is slightly below the reported values (0.446 vs. 0.499, Δ = 0.053), while yield is very close to literature (0.99 vs. 0.9979, Δ = 0.0079). Incomplete methanol conversion emerges as the primary optimization lever, pointing to adjustments in operating conditions (T, p), recycle/purge strategy, and H₂/CO control. Overall, the results confirm the technical feasibility of the simulated sections and support the development of a sisal-based, low-carbon Bio-DME route relevant to Northeast Brazil. Full article