Influence of 1-Butene Adsorption on the Dimerization Activity of Single Metal Cations on UiO-66 Nodes

Facile construction of zirconium/iron bimetallic organic frameworks for fluoride efficient removal from aqueous phase: An integrated experimental and theoretical investigation

This work presents the synthesis of Zr/Fe bimetallic organic frameworks (Zr/Fe-UiO-66) with varying compositions via a straightforward solvothermal method, targeting fluoride ions (F-) removal from the aqueous phase. Adsorption experiments elucidated the effect of factors (i.e., adsorbent dosage, initial concentration (C0), temperature, contact time and pH) on fluoride adsorption, and the parameters were optimized. The results show that the Zr/Fe-UiO-66(C) achieved the maximal uptake capacity of 164.4 mg/g, with the conditions of pH = 5.0, T = 298 K, C0 = 190 mg/L. The adsorption behavior of fluoride on Zr/Fe-UiO-66 can be well followed with the pseudo-second-order (PSO) kinetic model and the Sips isotherm model, described as the spontaneous, chemical driven and endothermic process. The adsorption mechanism was comprehensively explained by characterizations and microscopic simulations, such as molecular dynamics methods (MD) and independent gradient model analysis (IGM), which involves the chemical bonding, hydrogen-bond interaction and electrostatic interactions. Furthermore, Zr/Fe-UiO-66(C) exhibited excellent fluoride ion selectivity and superior stability. After 5 cycles of adsorption, Zr/Fe-UiO-66(C) maintained the removal efficiency of 83.4 % for F-. This research provides significant insights into the development of bimetallic metal-organic framework materials and fluoride removal research.

Defect-enabling zirconium-based metal-organic frameworks for energy and environmental remediation applications

This comprehensive review explores the diverse applications of defective zirconium-based metal-organic frameworks (Zr-MOFs) in energy and environmental remediation. Zr-MOFs have gained significant attention due to their unique properties, and deliberate introduction of defects further enhances their functionality. The review encompasses several areas where defective Zr-MOFs exhibit promise, including environmental remediation, detoxification of chemical warfare agents, photocatalytic energy conversions, and electrochemical applications. Defects play a pivotal role by creating open sites within the framework, facilitating effective adsorption and remediation of pollutants. They also contribute to the catalytic activity of Zr-MOFs, enabling efficient energy conversion processes such as hydrogen production and CO2 reduction. The review underscores the importance of defect manipulation, including control over their distribution and type, to optimize the performance of Zr-MOFs. Through tailored defect engineering and precise selection of functional groups, researchers can enhance the selectivity and efficiency of Zr-MOFs for specific applications. Additionally, pore size manipulation influences the adsorption capacity and transport properties of Zr-MOFs, further expanding their potential in environmental remediation and energy conversion. Defective Zr-MOFs exhibit remarkable stability and synthetic versatility, making them suitable for diverse environmental conditions and allowing for the introduction of missing linkers, cluster defects, or post-synthetic modifications to precisely tailor their properties. Overall, this review highlights the promising prospects of defective Zr-MOFs in addressing energy and environmental challenges, positioning them as versatile tools for sustainable solutions and paving the way for advancements in various sectors toward a cleaner and more sustainable future.

Computational design of metal hydrides on a defective metal-organic framework HKUST-1 for ethylene dimerization

Catalytic ethylene dimerization to 1-butene is a crucial reaction in the chemical industry, as 1-butene is used for the production of most common plastics (e.g., polyethylene). With well-defined tuneable structures and unsaturated active sites, defective metal-organic frameworks have recently emerged as potential catalysts for ethylene dimerization. Herein, we computationally design a series of metal hydrides on defective HKUST-1 namely H-M-DHKUST-1 (M: Co, Ni, Cu, Ru, Rh and Pd), and subsequently assess their catalytic activity for ethylene dimerization by density functional theory calculations. Due to the antiferromagnetic behavior of dimeric metal-based clusters, we comprehensively investigate all possible multiplicity states on H-M-DHKUST-1 and observe multiplicity crossing. The ground-state reaction barriers for four elementary steps (initiation, C-C coupling, β-hydride elimination and 1-butene desorption) are rationalized and C-C coupling is revealed to be the rate-determining step on H-Co-, H-Ni-, H-Ru-, H-Rh- and H-Pd-DHKUST-1. The energy barrier for β-hydride elimination is found to be the lowest on H-Ru- and H-Rh-DHKUST-1, attributed to the weak stability of agostic arrangement; however, the energy barrier for 1-butene desorption is the highest on H-Rh-DHKUST-1. Among the designed H-M-DHKUST-1, Co- and Ni-based ones are predicted to exhibit the best overall catalytic performance. The mechanistic insights from this study may facilitate the development of new MOFs toward efficient ethylene dimerization and other industrially important reactions.

Tunable zirconium-based metal organic frameworks synthesis for dibutyl phthalate efficient removal: An investigation of adsorption mechanism on macro and micro scale

The tunable porous structure of metal organic frameworks (MOFs) plays a crucial role in determining their adsorption performance. In this study, we developed and employed a strategy involving monocarboxylic acid assistance to synthesize a series of zirconium-based MOFs (UiO-66-F4) for the removal of aqueous phthalic acid esters (PAEs). The adsorption mechanisms were investigated by combining batch experiments, characterization and theoretical simulation. By adjusting the affecting factors (i.e., initial concentration, pH values, temperature, contact time and interfering substance), the adsorption behavior was confirmed as a spontaneous and exothermic chemisorption process. The Langmuir model provided a good fit, and the maximum expected adsorption capacity of di-n-butyl phthalate (DnBP) on UiO-66-F4(PA) was calculated to be 530.42 mg·g-1. Besides, through carrying out the molecular dynamics (MD) simulation, the multistage adsorption process in the form of DnBP clusters was revealed on a microcosmic scale. The independent gradient model (IGM) method showed the types of weak interactions of inter-fragments or between DnBP and UiO-66-F4. Furthermore, the synthesized UiO-66-F4 displayed excellent removal efficiency (>96 % after 5 cycles), satisfactory chemical stability and reusability in the regeneration process. Hence, the modulated UiO-66-F4 will be regarded as a promising adsorbent for PAEs separation. This work will provide referential significance in tunable MOFs development and actual applications of PAEs removal.