Metal-organic framework (MOF) nanoparticles, also called porous coordination polymers, are a major part of nanomaterials science, and their role in catalysis is becoming central. The extraordinary variability and richness of their structures afford engineering synergies between the metal nodes, functional linkers, encapsulated substrates, or nanoparticles for multiple and selective heterogeneous interactions and activations in these MOF-based nanocatalysts. Pyrolysis of MOF-nanoparticle composites forms highly porous N- or P-doped graphitized MOF-derived nanomaterials that are increasingly used as efficient catalysts especially in electro- and photocatalysis. This review first briefly summarizes this background of MOF nanoparticle catalysis and then comprehensively reviews the fast-growing literature reported during the last years. The major parts are catalysis of organic and molecular reactions, electrocatalysis, photocatalysis, and views of prospects. Major challenges of our society are addressed using these well-defined heterogeneous catalysts in the fields of synthesis, energy, and environment. In spite of the many achievements, enormous progress is still necessary to improve our understanding of the processes involved beyond the proof-of-concept, particularly for selective methane oxidation, hydrogen production, water splitting, CO2 reduction to methanol, nitrogen fixation, and water depollution.

State of the Art and Prospects in Metal-Organic Framework (MOF)-Based and MOF-Derived Nanocatalysis.

Hydrogen is the most effective and sustainable carrier of clean energy, and liquid-phase hydrogen storage materials with high hydrogen content, reversibility and good dehydrogenation kinetics are promising in view of "hydrogen economy". Efficient, low-cost, safe and selective hydrogen generation from chemical storage materials remains challenging, however. In this Review article, an overview of the recent achievements is provided, addressing the topic of nanocatalysis of hydrogen production from liquid-phase hydrogen storage materials including metal-boron hydrides, borane-nitrogen compounds, and liquid organic hydrides. The state-of-the-art catalysts range from high-performance nanocatalysts based on noble and non-noble metal nanoparticles (NPs) to emerging single-atom catalysts. Key aspects that are discussed include insights into the dehydrogenation mechanisms, regenerations from the spent liquid chemical hydrides, and tandem reactions using the in situ generated hydrogen. Finally, challenges, perspectives, and research directions for this area are envisaged.

Recent developments of nanocatalyzed liquid-phase hydrogen generation

Perspectives on the synthesis of organic carbamates

A nanocomposite able to function as a hydrogenation catalyst under strongly acidic conditions without the presence of noble metals is synthesized and thoroughly studied. This specially designed catalyst possesses a unique structure composed of carbon nitride (CN) with underlying nickel, in which the nickel endows the CN with new active sites for hydrogen adsorption and activation while it itself is physically isolated from the reactive environment and protected from poisoning or loss. The CN is inert for hydrogenation without the help of nickel. The catalyst shows good performance for hydrogenation of nitro compounds under strong acidic conditions, including the one-step hydrogenation of nitrobenzene in 1.5 M H2SO4 to produce p-amoniophenol, for which the acid in the reaction system has restricted the catalyst only to noble metals in previous studies. Further characterization has demonstrated that the nickel in the catalyst is in an electron-deficient state because some of its electron has been donated to...

Acid-Resistant Catalysis without Use of Noble Metals: Carbon Nitride with Underlying Nickel

Synthesis and characterization of versatile MgO–ZrO2 mixed metal oxide nanoparticles and their applications

Zn(OAc) 2 was found to give excellent catalytic performance for methyl N -phenyl carbamate (MPC) synthesis from aniline and dimethyl carbonate (DMC). However, after being used for only once it tended to lose activity because of the formation of ZnO by the reaction of Zn(OAc) 2 and methanol. Zn(OAc) 2 /SiO 2 was prepared by incipient impregnation and it gave excellent catalytic performance in MPC synthesis, on which aniline conversion and MPC yield were 98.1% and 93.8%, respectively. And Zn(OAc) 2 /SiO 2 was found to be more stable than Zn(OAc) 2 during the reaction. When Zn(OAc) 2 /SiO 2 was used for the fifth time, aniline conversion and MPC yield were found to be 64.3% and 38.1%, respectively. The Zn(OAc) 2 /SiO 2 catalyst was characterized by TG-DTA, ICP, FTIR, XRD and XPS. The characterization results suggested that the deactivation of Zn(OAc) 2 /SiO 2 was also due to the formation of ZnO and there were two reasons for the improved stability of Zn(OAc) 2 /SiO 2 catalyst. One was the formation of the Si–O–Zn bonds in Zn(OAc) 2 /SiO 2 catalyst, which increased the steric hindrance of Zn and consequently retarded the reaction between Zn(OAc) 2 and methanol. The other cause was the dehydration between methanol and the hydroxyl group on the SiO 2 surface, which reduced the chance of a reaction between methanol and Zn(OAc) 2 .

Investigation of supported Zn(OAc)2 catalyst and its stability in N-phenyl carbamate synthesis

BACKGROUND: A single-step conversion of nitrobenzene (NB) to p-aminophenol (PAP) through catalytic hydrogenation is a widely used synthesis route for PAP The main shortcoming of this route is the use of sulfuric acid for rearrangement of the phenylhydroxylamine (PHA) intermediate In this paper, S2O82−/ZrO2 (PSZ) solid acid and Pt-S2O82−/ZrO2 (Pt-PSZ) bifunctional catalysts were prepared for the synthesis of PAP in non-acid medium

RESULTS: Calcination temperature has a substantial effect on the acidity, structure and activity for PHA rearrangement of PSZ The highest PAP yield was 338% over PSZ calcined at 823 K when the reaction was carried out in water at 423 K A high PAP yield of 239% was achieved by a single-step reaction of nitrobenzene over Pt-PSZ bifunctional catalysts

CONCLUSION: PSZ solid acid exhibits high activity for PHA rearrangement Perfect tetragonal ZrO2 and much stronger acid sites play important roles in catalytic activity Inhibiting the hydrogenation activity by reducing the amount of Pt loading on Pt-PSZ can improve the competition of PHA rearrangement on acid sites with hydrogenation of PHA on metal active sites, resulting in better selectivity to PAP Copyright © 2008 Society of Chemical Industry

Synthesis of p-aminophenol from the hydrogenation of nitrobenzene over metal-solid acid bifunctional catalyst

Effect of hydrazine hydrate on the Ru–Zn/SiO2 catalysts performance for partial hydrogenation of benzene

Esterification of cyclohexene with formic acid over a peanut shell-derived carbon solid acid catalyst

BACKGROUND: Methyl N-phenyl carbamate (MPC) is an intermediate for the preparation of methylene diphenyl diisocyanate (MDI), which is an important monomer for polyurethane synthesis. The synthesis of MPC by the reaction of aniline and dimethyl carbonate (DMC) is becoming more and more attractive. However, most of the catalysts used in MPC synthesis are homogeneous and not environment-friendly. Therefore, it is important and necessary to develop a new kind of oxide catalyst, that is not only friendly to the environment, but also exhibits higher activity and longer service time.



RESULTS: A new heterogeneous catalyst, ZnO-TiO2, was prepared for MPC synthesis. ZnO-TiO2 catalyst with a molar ratio Ti/Zn = 2 and calcined at 673 K exhibited good catalytic activity: aniline conversion was 96.9% and MPC yield 66.7%.



CONCLUSION: ZnO-TiO2 exhibits better catalytic activity than ZnO or TiO2 alone, which may result from the formation of ZnTiO3 and Zn2TiO4. Compared with ZnTiO3, Zn2TiO4 has better selectivity for MPC synthesis. Lewis acid sites with weaker acid strength favour MPC synthesis. The catalyst activity can be recovered almost completely by calcination. Copyright © 2008 Society of Chemical Industry

Wei Xue

Papers

Investigation of supported Zn(OAc)2 catalyst and its stability in N-phenyl carbamate synthesis

Synthesis of p-aminophenol from the hydrogenation of nitrobenzene over metal-solid acid bifunctional catalyst

Effect of hydrazine hydrate on the Ru–Zn/SiO2 catalysts performance for partial hydrogenation of benzene

Esterification of cyclohexene with formic acid over a peanut shell-derived carbon solid acid catalyst

Clean synthesis of methyl N‐phenyl carbamate over ZnO‐TiO2 catalyst