Frontiers of Chemical Science and Engineering最新文献

This paper proposes an innovative simultaneous optimization approach for single and multi-component mass exchanger network synthesis (MENS). A retrofitted stage-wise superstructure and a parallelized random walk algorithm with compulsive evolution (RWCE) are adopted. An iterative calculation method is designed to satisfy the requirements of multi-component mass transfer, with a relaxation for the outlet composition of the lean streams. The parametric analysis shows that the relaxation coefficient plays a major role in driving the convergence of the method. To improve the robustness of the established model, an adaptive relaxation coefficient strategy is implemented for multi-component MENS problems. In a divergence situation, the outlet concentration of the lean stream can be adjusted automatically by a random relaxation coefficient. Finally, three industrial MENS examples are considered in this work, whose total annual cost (TAC) are reduced by 7179, 2212, and 551 $·year⁻¹. The corresponding optimization times are obtained to be 336, 125, and 145 s. The results indicate improvements in the economy and time, demonstrating that the parallelized RWCE can yield an optimal TAC and optimization efficiency compared to previous results. Overall, the adaptive relaxation coefficient strategy enhances the convergence for multi-component MENS problems.

The use of metal-organic frameworks (MOFs) as CO₂-gas-capture materials has attracted extensive research attention. In this study, two types of MOFs—Zn-MOF and ZnCe-MOF—were synthesized utilizing the microchannel reaction method, with water being employed as the solvent. The specific surface area, pore size, and pore volume of Zn-MOF and ZnCe-MOF were 1566.4 and 15.6 m²·g⁻¹, 0.65 and 7.32 nm, as well as 1.65 and 0.03 cm³·g⁻¹, respectively. Furthermore, Ce doping not only increased the pore size of ZnCe-MOF but also its adsorption energy from −0.19 eV (Zn-MOF) to −0.53 eV (ZnCe-MOF). At 298 K, the adsorption capacities of Zn-MOF and ZnCe-MOF were 0.66 and 0.74 mmol·g⁻¹, respectively. In addition, the CO₂ adsorption behaviors of Zn-MOF and ZnCe-MOF were linear and logarithmic, respectively. Theoretical calculations show that the results of adsorption thermodynamic simulations were consistent with the experiments. Thus, the preparation of ZnCe-MOF materials using a microchannel reactor provides a new approach for the continuous preparation of MOFs.

Enhancing nitrogen removal is a very active branch in municipal wastewater treatment research, toward this end, anammox technology is a sustainable solution. This review systematically outlines the strategies employed to enhance mainstream anammox performance, including nitrite accumulation and microbial enrichment based on partial nitrification coupled anammox and partial denitrification coupled anammox, developed to address the challenges of low ammonium content in wastewater, nitrate accumulation in the effluent, and the influence of organic matter. The characteristics and advantages of novel anammox-coupled processes, including partial nitrification and partial denitrification coupled anammox, endogenous partial denitrification coupled anammox, and denitrifying anaerobic methane oxic coupled anammox are also comprehensively discussed; these aim to ensure the highly efficient and stable operation of anammox under diverse wastewater conditions by constructing a composite biological nitrogen removal system based on anammox, supplemented by nitrification-denitrification and other processes. Additionally, a novel anammox application route including mainstream partial denitrification/anammox and absorptionbiodegradation as well as sidestream partial nitrification/anammox is proposed, and its application pathway in conceptual wastewater treatment plants is outlined, aiming to foster the development of cost-effective, efficient, and energy-saving advanced wastewater treatment processes. Finally, prospects are presented that indicate the gaps in contemporary research and potential future research directions. Overall, this review provides a reference for treating municipal wastewater with anammox and sheds new light on related strategies and nitrogen removal mechanisms.

Coal utilization, as a major energy source, raises sustainability concerns and environmental impacts, prompting researchers to explore blending it with other feedstocks. This study discusses hydrochar coal-water slurry (HC-CWS) preparation conditions, emphasizing apparent viscosity and exploring the influence of high ash content on char reactivity. The study highlights that the presence of free water in sludge is moderately influential, while high amounts of free water in raw sewage sludge (SS) and its near absence during hydrothermal carbonization (HTC) of SS are both unfavorable for enhancing the overall performance of coal-water slurry (CWS). HTC reduces the concentration of hydroxyl functional group, enhancing slurry performance and reducing ash content in HC-CWS, indicating that coal complements hydrochar (HC). High-temperature HC preparation is unsuitable for HC-CWS due to increased viscosity and decreased stability. In terms of ash content, the optimal pH and HC ratio for CWS are determined at 30% HC. The gasification reactivity of HC, prepared at 180 °C with a 30% HC ratio in CWS at R_0.5 is 6 × 10⁻³ and at R_0.9 is 9 × 10⁻³. However, increasing HC to 50% diminishes reactivity under CO₂ atmosphere. The inhibitory effect was observed with an increasing percentage of HC in CWS and the synergy factor decreased in the following order: 10% HC > 30% HC > 50% HC, i.e., from 1.04 to 0.35. The possible reason is the presence of high ash content and their similar initial gasification rates during its early stages.

Direct air capture (DAC) using amine-functionalized solid adsorbents holds promise for achieving negative carbon emissions. In this study, a series of additive-incorporated tetraethylenepentamine-functionalized SiO₂ adsorbents with varying tetraethylenepentamine and additive contents were prepared via a simple impregnation method, characterized by various techniques, and applied in the DAC process. The structure-performance relationship of these adsorbents in DAC was investigated, revealing that the quantity of active amine sites (or the tetraethylenepentamine content in the exposed layer), as determined by CO₂-TPD measurement, was an important factor affecting the adsorbent performance. This factor, which varied with the tetraethylenepentamine content, additive type, and additive content, showed a positive correlation with the CO₂ adsorption capacity of the adsorbents. The optimal adsorbent, 40TEPA-10PEG/SiO₂ containing 40 wt % tetraethylenepentamine and 10 wt % polyethylene glycol (Mn = 200), exhibited a stable CO₂ capacity of 2.1 mmol·g⁻¹ and amine efficiency of 0.22 over 20 adsorption–desorption cycles (adsorption at 400 ppm CO₂/N₂ and 30 °C for 60 min, and desorption at pure N₂ and 90 °C for 20 min). Moreover, even after deliberate accelerated oxidation treatment (pretreated in air at 100 °C for 10 h), the CO₂ capacity of 40TEPA-10PEG/SiO₂ remained at 2.0 mmol·g⁻¹. The superior thermal and oxidative stability of 40TEPA-10PEG/SiO₂ makes it a promising adsorbent for DAC applications.

Zeolites, with their exquisite microporous frameworks and tailorable acidities, serve as ubiquitous catalysts across a diverse spectrum of industrial applications, ranging from petroleum and coal processing to sustainable chemistry and environmental remediation. Optimizing their performance hinges on a thorough understanding of the structure-performance relationship. In situ solid-state nuclear magnetic resonance spectroscopy has emerged as a critical tool, providing unparalleled atomic-level insights into both structure and dynamic aspects of zeolite-catalyzed reactions. Herein, we review recent progress in the development and application of the in situ solid-state nuclear magnetic resonance technique to zeolite catalysis. We first review the in situ nuclear magnetic resonance techniques used in zeolite-catalyzed reaction, including batch-like and continuous-flow reaction modes. The conditions and limitations for these techniques are thoroughly summarized. Subsequently, we review the applications of in situ nuclear magnetic resonance techniques in zeolite-catalyzed reaction, focusing on some important catalytic reactions like methanol-to-hydrocarbons, ethanol dehydration, alkane activation, and beyond. Emphasis is placed on the strategies of specific in situ nuclear magnetic resonance methodologies to tackle critical challenges encountered in these fields, such as probing intermediates and unraveling reaction mechanisms. Additionally, we discuss the burgeoning opportunities and prospective challenges associated with in situ nuclear magnetic resonance studies of zeolite-catalyzed processes.

The rapid migration and separation of photoinduced carriers is a key factor influencing photocatalytic efficiency. Constructing an S-scheme heterojunction is a strategic technique to enhance the separation of photo-generated carriers and boost overall catalytic activity. Herein, a simple physical stirring technique was adopted to successfully fabricate a novel NiCo₂S₄/CoTiO₃ S-scheme heterojunction photocatalyst. Upon exposure to light, the NiCo₂S₄/CoTiO₃-10 specimen demonstrated an outstanding hydrogen evolution rate of 2037.76 µmol·g⁻¹·h⁻¹, exceeding twice the rate observed for the pristine NiCo₂S₄ (833.72 µmol·g⁻¹·h⁻¹). The experimental outcomes reveal that the incorporation of CoTiO₃ significantly enhances the charge separation and transfer within the system. Concurrently, the formation of the S-scheme mechanism facilitates the separation of carriers while maintaining high redox capabilities. This work introduces an innovative approach to forming S-scheme heterojunctions based on bimetallic sulfides, thereby offering new prospects for the efficient utilization of solar energy.

Biochar belongs to the category of low-cost, stable, and environmentally benign carbon-based materials. In this article, the reasons that highlight the advantages of biochar materials to be used in carbon dioxide (CO₂) adsorption are briefly viewed with recent examples. Also, the issues to be solved for recommending biochar materials in the practical applications are listed.

The dynamics of methanol within prototype methanol synthesis catalysts were studied using quasi-elastic neutron scattering. Three Cu-exchanged zeolites (mordenite, SSZ-13 and ZSM-5) were studied after methanol loading and showed jump diffusion coefficients between 1.04 × 10⁻¹⁰ and 2.59 × 10⁻¹⁰ m²·s⁻¹. Non-Arrhenius behavior was observed with varying temperature due to methoxy formation at Brønsted acid sites and methanol clustering around copper cations.

The lateral dispersion of bed material in a bubbling fluidized bed is a key parameter in the prediction of the effective in-bed heat transfer and transport of heterogenous reactants, properties important for the successful design and scale-up of thermal and/or chemical processes. Computational fluid dynamics simulations offer means to investigate such beds in silico and derive effective parameters for reduced-order models. In this work, we use the Eulerian-Eulerian two-fluid model with the kinetic theory of granular flow to perform numerical simulations of solids mixing and heat transfer in bubbling fluidized beds. We extract the lateral solids dispersion coefficient using four different methods: by fitting the transient response of the bed to (1) an ideal heat or (2) mass transfer problem, (3) by extracting the time-averaged heat transfer behavior and (4) through a momentum transfer approach in an analogy with single-phase turbulence. The method (2) fitting against a mass transfer problem is found to produce robust results at a reasonable computational cost when assessed against experiments. Furthermore, the gas inlet boundary condition is shown to have a significant effect on the prediction, indicating a need to account for nozzle characteristics when simulating industrial cases.