Microfluidic synthesis of a Zeolitic-Imidazole Framework ZIF-67 at ambient temperature and pressure is reported. With a metal/ligand/triethylamine (TEA) ratio of 1/4/4, ZIF-67 can be produced with a ...high space-time yield (STY) of 57000 kg m−3 d−1 and a production rate of 285 g h−1 in ethanol. It can be produced with a similar STY in water solution as well. Given the importance of sustainable synthesis, the recycling process of the mother liquor was investigated. The mother liquor can be recycled 5 times with high yield and crystallinity in ethanol, but not applicable in water solution. The morphology and particle sizes of ZIF-67 can be regulated in a controlling manner in a water-ethanol mixed solvent. Moreover, the influence of TEA on the characteristic of the ZIF-67 structure was investigated in detail.
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•A microfluidic strategy to produce ZIF-67 at ambient temperature and pressure is provided.•The mother liquor of ethanol can be recycled 5 times with high yield and crystallinity.•The particle sizes can be regulated in the nanometer range using an ethanol-water mixed solvent.
In the catalytic conversion of biomass-derived furfural to 2-methylfuran, a concerted combination of hydrogenation and hydrogenolysis is required. Highly dispersed MoP catalysts supported on SiO2 ...were prepared by incipient impregnation with the aid of citric acid and subsequent temperature-programmed hydrogen reduction. The prepared MoP/SiO2 exhibited a markedly high performance in the selective hydrodeoxygenation of furfural to 2-methylfuran. A full conversion of furfural with 96.3% selectivity to 2-methylfuran under mild reaction conditions (120 °C, 1.0 MPa, WHSV: 0.3 h–1) was obtained with over 20% MoP/SiO2 in a continuous fixed bed reactor. The oxophilicity of Mo species and surface acidity of MoP might enhance the adsorption of furfural and the subsequent cleavage of the C–O bond of the intermediate furfuryl alcohol, leading to considerably high selectivity to 2-methylfuran. The complexion of Mo species with citric acid improved the dispersion of MoP particles due to the controllable decomposition of the complex in the course of preparation. Although the activity of MoP/SiO2 decreased gradually with the reaction time in 50 h, it could be restored by in situ hydrogen reduction.
The removal of acetylene impurities is indispensable in the production of ethylene. An Ag-promoted Pd catalyst is industrially used to remove acetylene impurities by selective hydrogenation. It is ...highly desirable to replace Pd with non-precious metals. In the present investigation, CuO particles, which are most frequently used as the precursors for Cu-based catalysts, were prepared through the solution-based chemical precipitation method and used to prepare high-performance catalysts for selective hydrogenation of acetylene in large excess ethylene. The non-precious metal catalyst was prepared by treating CuO particles with acetylene-containing gas (0.5 vol% C
2
H
2
/Ar) at 120 °C and subsequent hydrogen reduction at 150 °C. The obtained catalyst was tested in selective hydrogenation of acetylene in a large excess of ethylene (0.72 vol% CH
4
as the internal standard, 0.45 vol% C
2
H
2
, 88.83 vol% C
2
H
4
, 10.00 vol% H
2
). It exhibited significantly higher activity than the counterpart of Cu metals, achieving 100% conversion of acetylene without ethylene loss at 110 °C and atmospheric pressure. The characterization by means of XRD, XPS, TEM, H
2
-TPR, CO-FTIR, and EPR verified the formation of an interstitial copper carbide (Cu
x
C), which was responsible for the enhanced hydrogenation activity.
A new active phase Cu
x
C is formed during the pretreatment process, enabling enhanced hydrogenation activity.
Highly dispersed Ni2P catalysts (Ni2P/SiO2-DPx) were prepared by reducing the passivation-free precursors, which were obtained through the phosphidation of nickel phyllosilicate with sodium ...hypophosphite. The strong metal–support interaction of nickel phyllosilicate and the mild phosphidation conditions prevented the agglomeration of Ni particles and resulted in a smaller Ni2P particle size. The superior catalytic performance of the as-prepared Ni2P/SiO2-DP catalysts was evaluated in hydrodesulfurization (HDS) of 4,6-dimethyldibenzothiophene and the hydrogenation of phenanthrene, in comparison with Ni2P/SiO2-IM and CoMoS/γ-Al2O3 prepared from a conventional incipient wetness impregnation method. The passivation-free Ni-P/SiO2-DPx precursors showed great storage stability, and Ni2P/SiO2-DP derived from the stored Ni-P/SiO2-DP precursors exhibited negligible loss of HDS activity. This method provides a potential preparation strategy for the industrial applications of transition metal phosphides without the temperature-programmed reduction and the subsequent passivation process.
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•Bifunctional Ni3P/γ-Al2O3 was prepared by an electroless plating method.•A deposition–precipitation method was adapted to improve the dispersion.•Ultrafine Ni3P particles (~3.8 nm) ...were dispersed homogeneously on γ-Al2O3.•Ni3P/γ-Al2O3 exhibited high performance and stability in phenol hydrodeoxygenation.
A bifunctional Ni3P/γ-Al2O3 catalyst was prepared by an electroless plating method and characterized by XRD, XPS, N2 adsorption–desorption, ICP, TEM, CO chemisorption, NH3 TPD, and Py-FTIR. To improve the dispersion of Ni3P on γ-Al2O3, highly dispersed nickel aluminum oxide hydrate was deposited on γ-Al2O3 by a deposition–precipitation procedure. The resulting Ni3P nanoparticles (~3.8 nm) were homogeneously dispersed on γ-Al2O3. The Ni3P/γ-Al2O3 catalyst exhibited high performance in the hydrodeoxygenation of phenol, in which both hydrogenation and dehydration were involved. The Ni3P/γ-Al2O3 was remarkably stable both in catalytic performance and in structure during a 100-h run.
In this work, we report the catalytic performance of a MoO2Cl2 anchored metal-organic framework, Mo@COMOC-4, in the oxidative desulfurization (ODS) process on a continuous fixed-bed reactor. ...Mo@COMOC-4 was examined as a catalyst in the oxidation of model oils containing dibenzothiophene (DBT), benzothiophene (BT) or 4,6-dimethyldibenzothiophene (4,6-DMDBT). In a 50-h ODS reaction of DBT at 70 °C, with tert-butyl hydroperoxide (TBHP) as the oxidant, a constant high DBT conversion of nearly 80% was observed along with a high oxidant utility of over 85%, where DBT was converted rapidly into DBT sulfone. XRD and ICP analysis show that the structure of Mo@COMOC-4 was well preserved, with no significant leaching of Mo species. In addition, Mo@COMOC-4 can also oxidize a hydrogenated diesel oil, and 74% sulfur removal efficiency was achieved, with an extraction recovery of 92.5% after acetonitrile extraction. Spectroscopic characterization confirmed the formation of a molybdenum peroxide complex from MoO2Cl2 under TBHP treatment, a plausible catalytic process was proposed based on the experiment evidence as well as FT-IR and FT-FIR characterization results.
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•A MoO2Cl2 anchored MOF catalyze oxidative desulfurization was examined on a fixed-bed reactor.•The catalyst showed high ODS activity for sulfur compounds and a diesel fuel.•Spectroscopic characterization gave insights to the Mo active sites under the oxidant treatment.•A plausible catalytic cycle was proposed based on the characterization results.
Hydrogen peroxide (H2O2) plays a vital role in various industries, from healthcare and pharmaceuticals to water treatment and electronics. Its importance lies in its versatility as a powerful and ...green oxidizing agent and disinfectant. However, with an anticipated increase in demand for H2O2, greener production methods are required. Photocatalytic H2O2 generation (from O2 and/or H2O) using Metal–Organic Frameworks (MOFs) and Covalent Organic Frameworks (COFs) has emerged as a sustainable alternative to traditional methods. This review provides a comprehensive overview of the intrinsic characteristics of MOFs and COFs, focusing on strategies to enhance light harvesting, charge separation, charge mobility, and the associated oxidation and reduction reactions. By addressing current limitations, this review elucidates the fundamental physicochemical properties of these materials, explores H2O2 production mechanisms, and outlines future directions for improved photocatalytic performance.
Iodoarenes are important precursors for fine chemicals and pharmaceuticals. The direct iodination of arenes using molecular iodine (I2) has emerged as an attractive green synthesis method. Most of ...the direct iodination protocols are still homogeneous systems that require harsh conditions and use or produce toxic products. We report a new heterogeneous catalytic route for the direct aerobic iodination of arenes under mild conditions using a PMoV2 polyoxometalate (POM) embedded in the metal–organic framework (MOF) MIL-101 (PMoV2@MIL-101). The catalyst shows full yield for the conversion of mesitylene to 2-iodomesitylene at a rate that is similar to the homogeneous POM system. Moreover, the catalyst is applicable for a wide range of substrates in an oxygen atmosphere without using any co-catalysts or sacrificial agents. To the best of our knowledge, this is the first report on designing a sustainable and green MOF-based heterogeneous catalytic system for the direct iodination reaction using molecular oxygen and iodine.
One-pot reactions offer economic and environmental advantages. Therefore, the design and synthesis of multifunctional catalysts capable of catalyzing multistep organic transformations are highly ...important. Herein, an effective bifunctional heterogeneous catalyst is presented. For the first time, the encapsulation of H5PMo10V2O40 (PMoV2) polyoxometalate into the cages of an alkylamine-modified MIL-101 using an optimized double-solvent method is reported. The obtained PMoV2@DETA-MIL-101 material displays a great catalytic performance (99% conversion of alcohols) for the selective aerobic oxidation-Knoevenagel one-pot reaction. To the best of our knowledge, this is one of the first reports on the usage of noble-metal-free catalysts for the aerobic oxidation-Knoevenagel one-pot reaction without the addition of additives. The catalyst is very stable and can be used for at least five cycles with no leaching of the active sites.
