Chem & Bio Engineering最新文献

One-step separation of ethylene (C₂H₄) from multicomponent mixtures poses significant challenges in the petrochemical industry due to the high similarity of involved gas molecules. Herein, we report a pillared-layer coordination network named Zn-fa-mtrz (H₂fa = fumaric acid; Hmtrz = 3-methyl-1,2,4-triazole) possessing pore surfaces decorated with methyl groups and electronegative N/O atoms. Molecular modeling reveals that the pore surface of Zn-fa-mtrz provides more and stronger multiple interaction sites to simultaneously enhance the adsorption affinity for CO₂ and C₂H₂ other than C₂H₄. The experimental and simulated breakthrough experiments demonstrate the ability to produce high-purity C₂H₄ (>99.97%) in one-step from ternary CO₂/C₂H₂/C₂H₄ gas mixtures.

One-step separation of ethylene (C₂H₄) from multicomponent mixtures poses significant challenges in the petrochemical industry due to the high similarity of involved gas molecules. Herein, we report a pillared-layer coordination network named Zn-fa-mtrz (H₂fa = fumaric acid; Hmtrz = 3-methyl-1,2,4-triazole) possessing pore surfaces decorated with methyl groups and electronegative N/O atoms. Molecular modeling reveals that the pore surface of Zn-fa-mtrz provides more and stronger multiple interaction sites to simultaneously enhance the adsorption affinity for CO₂ and C₂H₂ other than C₂H₄. The experimental and simulated breakthrough experiments demonstrate the ability to produce high-purity C₂H₄ (>99.97%) in one-step from ternary CO₂/C₂H₂/C₂H₄ gas mixtures.

In our previous work, the control of aluminum distribution on microporous ZSM-5 with and without the addition of sodium (Na) was conducted. In the current research, adjustment of the aluminum distribution on hierarchical ZSM-5 synthesized using a surfactant as a mesoporogen has been carried out. The investigation of aluminum distribution was based on ²⁷Al MAS NMR, constraint index (CI) value, and Co(II) ion-adsorbed UV-vis. The aforementioned characterizations revealed that the hierarchical ZSM-5 with Na exhibited a more concentrated aluminum distribution in the channel intersections than the hierarchical ZSM-5 without Na did. The opposite trend was observed with microporous ZSM-5. Furthermore, the influence of the hydrothermal synthesis time on the formation of the hierarchical structure and the arrangement of aluminum within the framework was also investigated. The prolongation of the hydrothermal synthesis time to 144 h was found to be an optimal period for the formation of a well-hierarchical structure, as demonstrated by the observed increase in the hierarchy factor. Moreover, this process resulted in an increase in the strength of the acid sites and a change in the crystal morphology of the hierarchical ZSM-5 from a coffin-like morphology to a coral reef-like or a flower-like morphology. Additionally, the influence of the alteration in the aluminum distribution on the catalytic performance was also investigated. In the case of the n-hexane cracking and methanol conversion reactions, hierarchical ZSM-5 with Na was observed to produce bulkier molecules (≥C5s) than that without Na. On the other hand, it was observed that the hierarchically structured ZSM-5 exhibited enhanced performance in the production of lower olefins, particularly propene, in comparison to the microporous ZSM-5.

In our previous work, the control of aluminum distribution on microporous ZSM-5 with and without the addition of sodium (Na) was conducted. In the current research, adjustment of the aluminum distribution on hierarchical ZSM-5 synthesized using a surfactant as a mesoporogen has been carried out. The investigation of aluminum distribution was based on ²⁷Al MAS NMR, constraint index (CI) value, and Co(II) ion-adsorbed UV–vis. The aforementioned characterizations revealed that the hierarchical ZSM-5 with Na exhibited a more concentrated aluminum distribution in the channel intersections than the hierarchical ZSM-5 without Na did. The opposite trend was observed with microporous ZSM-5. Furthermore, the influence of the hydrothermal synthesis time on the formation of the hierarchical structure and the arrangement of aluminum within the framework was also investigated. The prolongation of the hydrothermal synthesis time to 144 h was found to be an optimal period for the formation of a well-hierarchical structure, as demonstrated by the observed increase in the hierarchy factor. Moreover, this process resulted in an increase in the strength of the acid sites and a change in the crystal morphology of the hierarchical ZSM-5 from a coffin-like morphology to a coral reef-like or a flower-like morphology. Additionally, the influence of the alteration in the aluminum distribution on the catalytic performance was also investigated. In the case of the n-hexane cracking and methanol conversion reactions, hierarchical ZSM-5 with Na was observed to produce bulkier molecules (≥C5s) than that without Na. On the other hand, it was observed that the hierarchically structured ZSM-5 exhibited enhanced performance in the production of lower olefins, particularly propene, in comparison to the microporous ZSM-5.

Since the phenylalanine (Phe) dipeptide moiety is referred to as an essential structure for building amyloid-β peptide from Alzheimer's disease, its wonderful assembly ability to form nanofibers has been extensively studied. Cross-linked Phe-Phe-based peptide nanofibers can construct networks, thus encapsulating the drugs to form supramolecular hydrogels. Recently, scientists have proposed a variety of Phe-Phe-based macroscopic supramolecular hydrogels and used them in biomedical applications. Therefore, we summarize the construction strategies of Phe-Phe-based macroscopic supramolecular hydrogels and list their represented biomedical applications (e.g., wound healing, eye protection, cancer therapy, etc.) since the birth of Phe-Phe-based supramolecular hydrogels. In addition, we present the perspectives and challenges of Phe-Phe-based macroscopic peptide hydrogels.

Since the phenylalanine (Phe) dipeptide moiety is referred to as an essential structure for building amyloid-β peptide from Alzheimer’s disease, its wonderful assembly ability to form nanofibers has been extensively studied. Cross-linked Phe–Phe-based peptide nanofibers can construct networks, thus encapsulating the drugs to form supramolecular hydrogels. Recently, scientists have proposed a variety of Phe–Phe-based macroscopic supramolecular hydrogels and used them in biomedical applications. Therefore, we summarize the construction strategies of Phe–Phe-based macroscopic supramolecular hydrogels and list their represented biomedical applications (e.g., wound healing, eye protection, cancer therapy, etc.) since the birth of Phe–Phe-based supramolecular hydrogels. In addition, we present the perspectives and challenges of Phe–Phe-based macroscopic peptide hydrogels.

Carbon molecular sieves (CMS) with a tunable pore structure hold significant promise for efficient C₃H₆/C₃H₈ separation. However, understanding the relationship between a precursor’s carbon framework and the microstructure of carbonized products is still ambiguous and requires further investigation. Herein, a relative aliphaticity/aromaticity regulated strategy was proposed to tailor the carbon skeleton of the polyamide precursor, aiming to fine tune the CMS pore size between the kinetic diameter of C₃H₆ (4.68 Å) and C₃H₈ (5.11 Å). The relative aliphaticity/aromaticity of the precursor was rationally modulated by replacing aromatic rings in diamine monomers with aliphatic chains of different lengths. Results indicated that polyamide precursors with higher relative aliphaticity exhibited increased susceptibility to fragmentation during carbonization. Thus, a higher degree of carbon layer restructuring arising from the degradation of aliphatic chains promoted the formation of orderly graphitized structures with sub 5 Å ultramicropores. The ETDA-derived CMS pyrolyzed at 700 °C (ETDA700) exhibited outstanding sieving performance in separating C₃H₆ from C₃H₈, with C₃H₆ uptakes of up to 2.33 mmol/g, while propane adsorption capacity was negligible. This work may provide valuable insights for the design of sieving carbonaceous material by rationally tuning precursor properties for the efficient separation of gas mixtures with similar sizes.

Carbon molecular sieves (CMS) with a tunable pore structure hold significant promise for efficient C₃H₆/C₃H₈ separation. However, understanding the relationship between a precursor's carbon framework and the microstructure of carbonized products is still ambiguous and requires further investigation. Herein, a relative aliphaticity/aromaticity regulated strategy was proposed to tailor the carbon skeleton of the polyamide precursor, aiming to fine tune the CMS pore size between the kinetic diameter of C₃H₆ (4.68 Å) and C₃H₈ (5.11 Å). The relative aliphaticity/aromaticity of the precursor was rationally modulated by replacing aromatic rings in diamine monomers with aliphatic chains of different lengths. Results indicated that polyamide precursors with higher relative aliphaticity exhibited increased susceptibility to fragmentation during carbonization. Thus, a higher degree of carbon layer restructuring arising from the degradation of aliphatic chains promoted the formation of orderly graphitized structures with sub 5 Å ultramicropores. The ETDA-derived CMS pyrolyzed at 700 °C (ETDA700) exhibited outstanding sieving performance in separating C₃H₆ from C₃H₈, with C₃H₆ uptakes of up to 2.33 mmol/g, while propane adsorption capacity was negligible. This work may provide valuable insights for the design of sieving carbonaceous material by rationally tuning precursor properties for the efficient separation of gas mixtures with similar sizes.

Regulating both crystallographic orientation and thickness of titanium metal–organic framework (Ti-MOF) membranes remains a significant challenge. In this study, we pioneered the fabrication of uniform 29 nm thick NH₂-MIL-125 nanosheet seeds by employing crystallization kinetics modulation approach. Through innovating confined counter-diffusion-assisted epitaxial growth under single-mode microwave heating, a highly c-oriented 80 nm thick NH₂-MIL-125 membrane was prepared. Significant reduction in thickness endowed the membrane with unprecedented H₂ permeance (1350 GPU) along with considerable H₂/CO₂ selectivity (19.1), exceeding the performance benchmarks of state-of-the-art NH₂-MIL-125 membranes.

Highly selective capture and separation of propylene (C₃H₆) from ethylene (C₂H₄) presents one of the most crucial processes to obtain pure C₂H₄ in the petrochemical industry. The separation performance of current physisorbents is commonly limited by insufficient C₃H₆ binding affinity, resulting in poor low-pressure C₃H₆ uptakes or inadequate C₃H₆/C₂H₄ selectivities. Herein, we realize a unique single-molecule C₃H₆ nanotrap in an ultramicroporous MOF material (Co(pyz)[Pd(CN)₄], ZJU-74a-Pd), exhibiting the benchmark C₃H₆ capture capacity at low-pressure regions. This MOF-based nanotrap features the sandwichlike strong multipoint binding sites and the perfect size match with C₃H₆ molecules, providing an ultrastrong C₃H₆ binding affinity with the maximal Q_st value (55.8 kJ mol^–1). This affords the nanotrap to exhibit one of the highest C₃H₆ uptakes at low pressures (60.5 and 103.8 cm³ cm^–3 at 0.01 and 0.1 bar) and record-high C₃H₆/C₂H₄ selectivity (23.4). Theoretical calculations reveal that the perfectly size-matched pore cavities combined with sandwichlike multibinding sites enable this single-molecule C₃H₆ nanotrap to maximize the C₃H₆ binding affinity, mainly accounting for its record low-pressure C₃H₆ capture capacity and selectivity. Breakthrough experiments further confirm its excellent separation capacity for actual 1/99 and 50/50 C₃H₆/C₂H₄ mixtures, affording the remarkably high pure C₂H₄ productivities of 17.1 and 3.4 mol kg^–1, respectively.