AIChE Journal最新文献

This work proposed a pyrolysis chemical looping reforming-two stage regeneration (PCLR-TR) process with carbon-negative syngas and biochar poly-generation，aimed at overcoming challenges in chemical looping gasification. The process effectively separates pyrolysis and reforming, circumventing slow solid–solid reactions and enabling the flexible adjustment of the H₂/CO ratio. The two-stage regeneration ensures improved synchronization of reaction rates across different reactors. The results indicate that manipulation of process parameters allows for flexible adjustment of the H₂/CO ratio in syngas (ranging from 1.02 to 3.83). The introduction of CO₂ feed in the first stage regeneration reactor reduces the oxygen carrier exothermic intensity in the second stage regeneration reactor by 58%. Optimization results suggest that the generated syngas is compatible with diverse downstream applications, exhibiting a maximum CO₂ negative emission of 1.85 kg/kg syngas. The PCLR-TR system offers a versatile and environmentally friendly solution for the energy and chemical industries.

Mg and its related solid base catalysts have always been thought of with weak or medium basicity. Herein, we present the synthesis of Mg single atom catalyst (Mg₁/NPC) with strong basicity by tuning its coordination environment, which shows unusual activity in strong-base-catalyzed transesterification reaction. Mg₁/NPC were obtained through impregnation-pyrolysis method, results manifest Mg single atoms are embedded in nitrogen doped carbon in penta-coordination (Mg-C₃N₂) which endows Mg single atoms with strong basicity and is in contrast to traditional alkaline-earth metal oxides. The novel Mg₁/NPC exhibits excellent activity (40.2%) and stability in transesterification of methanol and ethylene carbonate to produce dimethyl carbonate (DMC), outperforming all state-of-the-art Mg-based solid base catalysts thus far reported as well as Ca, Na, and K-based catalysts with superbasicity (2.5%–39.2%). This work might pave the way for the advancement of novel solid base catalysts with extraordinary sources of basicity for multifarious applications.

A novel solvent extraction system was developed to separate Y³⁺ from Sr²⁺, where tributyl phosphate was chosen as an extractant and an organic solvent was a hydrophobic deep eutectic solvent (DES) consisting of oleic acid (OA) and 1-butyl-3-methylimidazolium chloride ([BMIM]Cl). The extraction experiment demonstrated that the extraction system using OA-[BMIM]Cl DES as an organic solvent exhibited great advantages of fast extraction and excellent selectivity for Y³⁺ (Y/Sr separation factor >500), which are hardly achieved in the extraction systems using conventional molecular solvent, for example, n-heptane. Density functional theory calculations also confirmed that the Y/Sr separation is more thermodynamically favorable in OA-[BMIM]Cl DES as an organic solvent compared to n-heptane. An extraction process comprising two-stage extraction, one-stage scrubbing, and one-stage stripping was proposed, achieving 95.06% of Y³⁺ selectively separated from a simulated solution and Y purity of 98.55% in the final product.

We report measurements performed to understand the effects of gas (Q_G) and liquid (Q_L) flow rates, surface tension (σ_GL), liquid viscosity (μ_L), and particle diameter (d_p) on dynamics of local liquid spreading, pressure drop, and overall liquid holdup in a pseudo-2D trickle bed. We show that an increase in the gas-phase inertia leads to a decrease in the lateral liquid spreading, whereas an increase in the liquid-phase inertia leads to an increase in the lateral liquid spreading. We also show that an increase in d_p causes a reduction in the lateral liquid spreading. Using dimensionless numbers (AB and We), we propose a regime map showing contributions of different forces to the local liquid spreading. We show that the interplay between the inertia and capillary forces governs the liquid distribution near the inlet, whereas the relative contribution of gravitational force increases toward the outlet. Finally, we propose a relation between AB and We for “bed-scale” liquid spreading.

Among various products from electrocatalytic CO₂ reduction (CO₂ER), HCOOH is highly profitable one. However, the slow kinetics of anodic oxygen evolution reaction lowers overall energy efficiency, which can be replaced by an electro-oxidation reaction with low thermodynamic potential and fast kinetics. Herein, we report an electrolysis system coupling CO₂ER with 5-hydroxymethylfurfural oxidation reaction (HMFOR). A BiOCl–CuO catalyst was designed to sustain CO₂ER to HCOOH at partial current density of 500 mA/cm² with FE_HCOOH above 90% and 700 mA/cm² with FE_HCOOH above 80%. In situ and ex situ x-ray absorption fine structure was used to capture the structure transform of BiOCl–CuO into metallic Bi and Cu during CO₂ER process, and the presence of CuO will promote this transformation which are supported by DFT calculations. Coupling HMFOR with CO₂ER, we realize both FE_HCOOH and FE_FDCA above 95% simultaneously, providing new prospects vista for the electrosynthesis of value-added products from paired system.

Herein, the first photochemical microscale continuous oscillatory baffled reactor, that is, Photo-μCOBR, was designed and evaluated. Computational fluid dynamics simulations were used to optimize the key structural parameter and operating conditions. Then, the mixing process was simulated and the μCOBR was shown to be more than 23 times faster than the straight channel both under oscillating conditions. Finally, a glass Photo-μCOBR was fabricated by femtosecond laser internal engraving technology, and the photocatalytic gas–liquid oxidation of dihydroartemisinic acid was performed. A yield of 65.9% was achieved in a residence time of ~120 s and at a gas–liquid flow rate ratio of 1:3 (vs. 18.6% in the capillary photomicroreactor under identical conditions). The results in this work offer guidelines for the design and operation of microscale COBRs, and the as-fabricated Photo-μCOBR displays good potential for gas–liquid photochemical reactions.

Ionic liquids' (ILs) surface tension, vital in liquid interface research, faces challenges in measurement methods—time-consuming and labor-intensive. The Structure-Surface Tension Relationship (SSTR) is crucial for understanding the surface tension laws of ionic liquids, helping to predict surface tension and design ionic liquids that meet target requirements. In this study, SMILES string and group contribution methods were used to generate descriptors, and the random forest and multi-layer perceptron (MLP) models were cross combined with the two descriptor generation methods to establish the SSTR model, providing a comprehensive framework for predicting the surface tension of ionic liquids. String-MLP excels with high accuracy (R² = 0.995, RMSE = 0.686, AARD% = 0.71%) for diverse ILs' surface tension values. Meanwhile, the Shapley Additive exPlanning (SHAP) method was used to test the impact of different features on model prediction, increasing the transparency and interpretability of the model.

Carbon molecular sieve (CMS) membranes are attractive for energy-efficient gas separations. A challenge with the fabrication of a high-performance CMS membrane is fine-tuning its microstructure for precise and efficient separation. This necessitates a molecular-scale analysis to understand its microstructure–performance relationship. Herein, molecular simulations were performed to unravel the relationships between four similar-sized CMS matrices with different microstructural characteristics (e.g., chemical composition and micromorphology) and their gas transport properties. Results show that the disordered packing of carbon layers, leading to the formation of ultramicropore (2–7 Å), originates from stereoscopic sp³ hybridized carbon atoms rather than non-carbon (oxygen) atoms. The size-sieving ability of CMS depends positively on ultramicroporosity; the adsorption capacity is strengthened and then weakened with the increase of ultramicroporosity. Competitive effects are observed in binary-mixture transport, and it is expected that the separation performance can be optimized by a reasonable distribution of ultramicropores combined with the affinity of oxygen-containing species.

There are few studies of mass transfer to nanospheres (1 nm ≤ d_p ≤ 100 nm). We have experimentally investigated the electrocatalytic reduction of hexacyanoferrate (III) to hexacyanoferrate (II) on gold nanospheres. The surface flux is insensitive to particle sizes of d_p ≥ 30 nm and is essentially identical to that for a diffusion-limited system. However, the measured fluxes in the range 5 nm ≤ d_p ≤ 30 nm were one to three orders of magnitude smaller than predicted by a purely diffusion-limited model. Using mathematical modeling, we evaluated six mechanisms affecting mass transfer to a nanoparticle in our experimental system. Among potential acceleratory effects, the curvature effect sharply increased the surface flux by a factor of 20. Other acceleratory effects of Brownian advection and enhanced surface reactivity played negligible roles, the latter due to screening by a charged stabilizing layer. Deceleratory effects of increased tortuosity by stabilizing layers and particle aggregation also played negligible roles. Electrostatic repulsion dominated mass transfer for d_p ≤ 30 nm. This finding suggests tuning the charge and the tortuosity of the stabilizer layer to potentiate the flux will be useful in engineering nanosuspensions.

Electrocatalytic urea removal is a promising technology for artificial kidney dialysis and wastewater treatment. Urea electrooxidation was studied on nickel electrocatalysts modified with Cr, Mo, Mn, and Fe. Mass transfer limits were observed for urea oxidation at physiological concentrations (10 mmol L$��{�\hspace{0.17em}�}^{�-�1�}�$). Urea oxidation kinetics were explored at higher concentrations (200 mmol L$��{�\hspace{0.17em}�}^{�-�1�}�$), showing improved performance, but with lower currents per active site. A simplified dialysis model was developed to examine the relationship of mass transfer coefficients and extent of reaction on flowrate, composition, and pH of the reacting stream. For a nickel hydroxide catalyst operating at 1.45 V$��{�\hspace{0.17em}�}_{�\text{RHE}�}�$, 37 $��{�\hspace{0.17em}�}^{�°�}�\text{C}�$, and pH 7.1, the model shows a minimum geometric electrode area of 1314 cm² is needed to remove 3.75 g urea h$��{�\hspace{0.17em}�}^{�-�1�}�$ with a flow rate of 200 mL min$��{�\hspace{0.17em}�}^{�-�1�}�$ for continuous operation.