Canadian Journal of Chemical Engineering最新文献

Amid the ongoing energy crisis, the demand for ecofriendly fuel has skyrocketed. Hydrogen (H₂) is a clean energy source showcasing exciting potential to be the fuel of future. It can be produced through water–gas shift (WGS) reaction. Presently, the catalysts used for WGS reaction have some limitations–thermal sintering, carbon monoxide (CO) poisoning and lack of applicability to small scale operations. To minimize these obstacles, a microkinetic model (MKM) has been developed to identify most active transition metal catalysts as well as bimetallic alloy catalysts for WGS reaction. The MKM is constructed over stepped (211) sites of transition metal catalyst using CatMAP, wherein carbon and oxygen binding energies are used as descriptors. At the reaction conditions of 573 K, and 10 bar, with an initial conversion of 10%, Cu exhibited the maximum turnover of 10⁻⁴ s⁻¹ and the activity trend is noted to be–Cu > Co > Pt > Ni > Rh > Ru > Pd > Au > Ag. Most of the monometallic catalysts exhibited lower turnovers due to catalyst deactivation. To eradicate this problem, bimetallic alloys of Cu, Co, Pt, and Ni-based catalysts were explored whereby Cu₃Rh and Cu₃Pt were identified as potential alloy catalysts lying at the top of the volcano curve (~10⁻² s⁻¹) for the reaction. Besides these, Co₃Pt, Co₃Pd, Cu₃Ni, Pt₃Cu, Ni₃Pt, and Ni₃Pd also exhibited turnover rates (~10⁻³ s⁻¹) higher than the most active monometallic catalysts. These findings reveal high-performance catalysts, which may subsequently be tested experimentally.

Amid the ongoing energy crisis, the demand for ecofriendly fuel has skyrocketed. Hydrogen (H₂) is a clean energy source showcasing exciting potential to be the fuel of future. It can be produced through water–gas shift (WGS) reaction. Presently, the catalysts used for WGS reaction have some limitations–thermal sintering, carbon monoxide (CO) poisoning and lack of applicability to small scale operations. To minimize these obstacles, a microkinetic model (MKM) has been developed to identify most active transition metal catalysts as well as bimetallic alloy catalysts for WGS reaction. The MKM is constructed over stepped (211) sites of transition metal catalyst using CatMAP, wherein carbon and oxygen binding energies are used as descriptors. At the reaction conditions of 573 K, and 10 bar, with an initial conversion of 10%, Cu exhibited the maximum turnover of 10⁻⁴ s⁻¹ and the activity trend is noted to be–Cu > Co > Pt > Ni > Rh > Ru > Pd > Au > Ag. Most of the monometallic catalysts exhibited lower turnovers due to catalyst deactivation. To eradicate this problem, bimetallic alloys of Cu, Co, Pt, and Ni-based catalysts were explored whereby Cu₃Rh and Cu₃Pt were identified as potential alloy catalysts lying at the top of the volcano curve (~10⁻² s⁻¹) for the reaction. Besides these, Co₃Pt, Co₃Pd, Cu₃Ni, Pt₃Cu, Ni₃Pt, and Ni₃Pd also exhibited turnover rates (~10⁻³ s⁻¹) higher than the most active monometallic catalysts. These findings reveal high-performance catalysts, which may subsequently be tested experimentally.

This study investigates the impact of torrefaction on municipal solid waste (MSW) fractions, focusing on energy recovery, calorific value enhancement, mass yield reduction, and energy densification under both nitrogen (N₂) and carbon dioxide (CO₂) atmospheres. As waste production increases globally, driven by population growth and industrialization, there is growing interest in waste-to-energy conversions to address both energy demand and waste management concerns. Torrefaction, a thermochemical pretreatment, enhances the properties of solid waste to make them more suitable for energy recovery processes like pyrolysis and gasification. This study demonstrated that torrefaction effectively addresses the low energy content of MSW, achieving an energy densification ratio up to 1.73. The process showed high energy efficiency, with energy recovery ranging from 69.3% to 99.15%, while different waste fractions exhibited varied behaviours during torrefaction. Lemon peels exhibited the highest energy densification while paper cups achieved the highest energy recovery but minimal energy densification. Wood waste fractions, such as white spruce sawdust and forest residues, demonstrated balanced performance with high energy recovery and moderate energy densification, making them ideal candidates for prioritizing high energy recovery applications. The results show that the use of CO₂, representing flue gas, enhances volatile release and improves energy densification in some fractions, particularly forest residues, compared to N₂, while also promoting better carbon retention at higher temperatures. Overall, this study highlights the importance of waste stream selection, torrefaction atmosphere, and temperature optimization to improve the efficiency of MSW torrefaction, offering insights for the use of flue gas torrefaction in waste-to-energy processes.

To address the difficulty of fault detection in nonlinear, dynamic, and multi-stage processes, a spatiotemporal neighbour centre distance (SNCD) statistic is proposed. SNCD is combined with t-distributed stochastic neighbour embedding (t-SNE) and back propagation neural network (BPNN) to develop the t-SNE-BPNN-SNCD (tB-SNCD) fault detection method. The t-SNE-BPNN leverages BPNN to learn the nonlinear implicit mapping relationships during the t-SNE feature extraction and dimensionality reduction process, solving the problem of embedding new samples in t-SNE. SNCD utilizes not only the spatial neighbour information of samples but also their temporal neighbour information, providing a more comprehensive extraction of process features, eliminating the autocorrelation of process data, and overcoming the difficulties posed by the dynamics of the process for fault detection. Since SNCD makes decisions based on the neighbourhood of samples, it is applicable to nonlinear, multi-stage processes. The performance of tB-SNCD is tested through numerical simulation processes and the Tennessee Eastman process, showing a higher fault detection rate compared to KPCA, DPCA, DKPCA, KNN, PC-WKNN, and LOF methods. Particularly, when faults are time-related, the fault detection rate of tB-SNCD is significantly higher than that of classical methods.

This study presents a new, data-driven review of Fischer–Tropsch (FT) synthesis by systematically analyzing the interplay between reaction parameters and product selectivity using a comprehensive literature-derived dataset. Unlike conventional reviews that focus solely on descriptive trends, this work integrates a structured data matrix comprising 11 input variables and 21 output responses, enabling a quantitative evaluation of process–performance relationships. Moreover, a generalized kinetic model that departs from conventional assumptions of fixed reaction orders is developed and compared. By employing regression techniques on estimated kinetic data, both empirical and mechanistic models are assessed, with particular emphasis on the underexplored role of water in modulating catalytic behaviour. The findings reveal that water exerts a positive influence on olefin production by promoting surface-active carbon formation, though this effect diminishes with increasing hydrocarbon chain length. Molecular dynamics simulations further support this by showing enhanced water-metal interactions, particularly for Fe–Ni alloys. The study also employs analysis of variance (ANOVA) to quantify the binary effects of operating conditions on conversion and selectivity (olefin/paraffin with carbon number up to 10). Altogether, this work not only consolidates kinetic insights but also introduces a predictive framework for understanding and optimizing FT synthesis performance, offering fresh perspectives for catalyst and process design.

Hierarchically hollow structures of AlOOH and Al₂O₃ were hydrothermally fabricated employing Al₂(SO₄)₃ obtained from the aluminium residue in zinc hydrometallurgy, which exhibited the excellent removal capacities and rates for methyl blue. The unique hollow spherical structures composed of numerous nanosheets offer the high specific surface areas. the adsorption begins, equilibrium can be reached within 10 min. The maximum adsorption capacities are 224.85 and 415.53 mg · g⁻¹ on hollow structures of AlOOH and Al₂O₃, respectively. The adsorption conforms to the pseudo-second-order model and can be described by the Redlich–Peterson model. In addition, the two hollow spherical structures have good regeneration performance. Hollow spherical structures have the advantages of low cost, simple synthesis, fast adsorption rates, and large capacities, and are the qualified alternatives for the dyes removal.

CO₂ methanation with Ni/Al₂O₃ catalysts is a key technology for converting CO₂ emissions into sustainable methane. However, conventional impregnation synthesis often results in poor nickel dispersion and in the emission of gaseous NO_x species. Thus, for the first time, sodium palmitate flocculant properties were used to isolate nickel nanoparticles and disperse them over an Al₂O₃ support. Ni/Al₂O₃ catalysts were synthesized by mechanochemical and wet impregnation methods (MI and WI, respectively) to evaluate the impact of the synthesis route on the catalytic performance. Nickel nanoparticles with 9.7–12.6 nm were produced. Influences of temperature (300–500°C) and gas hourly space velocity (GHSV, 2490–14,920 h⁻¹) were evaluated, and a stability study was performed. Best performances were reached at 400°C and the lowest GHSV (2490 h⁻¹). Ni/Al₂O₃-WI catalyst showed a slightly better performance in terms of CO₂ and H₂ conversion ($��X_{{\mathrm{CO}}_2}�=�79�\%�$, $��X_{H_2}�=�77�\%�$), when compared to Ni/Al₂O₃-MI ($��X_{{\mathrm{CO}}_2}�=�77�\%�$, $��X_{H_2}�=�76�\%�$). In addition, CH₄ selectivity was kept stable at >99% for all studies. The stability test showed that Ni/Al₂O₃-WI had a stable performance during the 50 h. These results indicate that this synthesis approach is a viable method for producing catalysts with strong activity and reduced environmental impact. Furthermor

The oxygen evolution reaction (OER) is a critical step in water electrolysis and has long been recognized as the primary bottleneck of the process, owing to its inherently sluggish kinetics and significant energy demands when compared to the hydrogen evolution reaction (HER). Transition metal oxides have been identified as promising electrocatalytic materials for the OER, attributed to their low cost, high catalytic activity, thermodynamic stability, and ease of synthesis and scalability. Among these, NiMo-oxide-based materials exhibit particularly advantageous electrochemical and structural properties, making them strong candidates for OER electrocatalysis. In our previously published study (Part I of the series), NiMo-oxide nanostructures with varying physicochemical properties and microstructures were synthesized via the solution combustion method by systematically modifying key experimental parameters and subsequently tested as HER electrocatalysts. In the current study, the electrocatalytic performance of these materials was thoroughly investigated in the context of the OER in an alkaline medium. The results demonstrated that the β-NiMoO₄ phase exhibited superior OER activity compared to the α-phase. Notably, the in-house catalyst outperformed the benchmark IrO₂, achieving a lower overpotential at 10 mA cm⁻² (289 mV vs. 429 mV for IrO₂) and a Tafel slope of 47 mV dec⁻¹. Furthermore, the catalyst demonstrated exceptional stability during the 24 h polarization test. The observed enhancement in long-term performance was attributed to the formation of NiOOH and the increased surface area of the electrocatalytic layer.

The oxygen evolution reaction (OER) is a critical step in water electrolysis and has long been recognized as the primary bottleneck of the process, owing to its inherently sluggish kinetics and significant energy demands when compared to the hydrogen evolution reaction (HER). Transition metal oxides have been identified as promising electrocatalytic materials for the OER, attributed to their low cost, high catalytic activity, thermodynamic stability, and ease of synthesis and scalability. Among these, NiMo-oxide-based materials exhibit particularly advantageous electrochemical and structural properties, making them strong candidates for OER electrocatalysis. In our previously published study (Part I of the series), NiMo-oxide nanostructures with varying physicochemical properties and microstructures were synthesized via the solution combustion method by systematically modifying key experimental parameters and subsequently tested as HER electrocatalysts. In the current study, the electrocatalytic performance of these materials was thoroughly investigated in the context of the OER in an alkaline medium. The results demonstrated that the β-NiMoO₄ phase exhibited superior OER activity compared to the α-phase. Notably, the in-house catalyst outperformed the benchmark IrO₂, achieving a lower overpotential at 10 mA cm⁻² (289 mV vs. 429 mV for IrO₂) and a Tafel slope of 47 mV dec⁻¹. Furthermore, the catalyst demonstrated exceptional stability during the 24 h polarization test. The observed enhancement in long-term performance was attributed to the formation of NiOOH and the increased surface area of the electrocatalytic layer.