Ionic Liquid Mediated In Situ Synthesis of Ru Nanoparticles for CO2 Hydrogenation Reaction

Ionic Liquids in Metal, Photo-, Electro-, and (Bio) Catalysis

Ionic liquids (ILs) have unique physicochemical properties that make them advantageous for catalysis, such as low vapor pressure, non-flammability, high thermal and chemical stabilities, and the ability to enhance the activity and stability of (bio)catalysts. ILs can improve the efficiency, selectivity, and sustainability of bio(transformations) by acting as activators of enzymes, selectively dissolving substrates and products, and reducing toxicity. They can also be recycled and reused multiple times without losing their effectiveness. ILs based on imidazolium cation are preferred for structural organization aspects, with a semiorganized layer surrounding the catalyst. ILs act as a container, providing a confined space that allows modulation of electronic and geometric effects, miscibility of reactants and products, and residence time of species. ILs can stabilize ionic and radical species and control the catalytic activity of dynamic processes. Supported IL phase (SILP) derivatives and polymeric ILs (PILs) are good options for molecular engineering of greener catalytic processes. The major factors governing metal, photo-, electro-, and biocatalysts in ILs are discussed in detail based on the vast literature available over the past two and a half decades. Catalytic reactions, ranging from hydrogenation and cross-coupling to oxidations, promoted by homogeneous and heterogeneous catalysts in both single and multiphase conditions, are extensively reviewed and discussed considering the knowledge accumulated until now.

Synthesis and Catalytic Application of Ru-Deposited Magnetic nanoparticles for the selective hydrogenation of CO2 gas

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In this report, a hybrid terpyridine (tpy) ligand functionalized with magnetic support was synthesized to obtain well-dispersed Ru NPs with a 2.0±0.5 nm mean size. This material was further analyzed using different analytical techniques before utilizing it as a catalyst for the CO¬2 hydrogenation reaction. A noticeable application of Ru-deposited magnetic nanoparticles as catalysts was observed during the CO2 hydrogenation. We successfully synthesized the formic acid with a high TON value under high-pressure reaction conditions. Easy recovery of the catalyst under the applied magnetic field helped us to reuse the catalyst up to 6 times with good TON and TOV value.

Direct Synthesis of Formic acid from Carbon Dioxide by Hydrogenation over Ruthenium Metal Doped Titanium Dioxide Nanoparticles in Functionalized Ionic Liquid

Background:

Presently worldwide manufacturing of formic acid follows the permutation of methanol and carbon monoxide in presence of a strong base. But due to the use of toxic CO molecule and easy availability of CO2 molecule in the atmosphere, most of the research has been shifted from the conventional method of formic acid synthesis to direct hydrogenation of CO2 gas using different homogenous and heterogeneous catalysts.

Objective:

To develop reaction protocol to achieve easy CO2 hydrogenation to formic acid using Ionic liquid reaction medium.

Methods:

We used the sol-gel method followed by calcination (over 250oC for 5 hours) to synthesize two types of ruthenium metal-doped TiO2 nanoparticles (with and without ionic liquids), namely Ru@TiO2@IL and Ru@TiO2. We are reporting the application NR2 (R= CH3) containing imidazolium- based ionic liquids not only to achieve a good reaction rate but also to get agglomeration free ruthenium metal-doped TiO2 nanoparticles along with easy product isolation due to the presence of NR2 (R= CH3) functionality in ionic liquid structure. We synthesized various NR2 (R= CH3) functionalized ionic liquids such as 1-Butyl-3-methylimidazolium Chloride, 1,3-di(N,Ndimethylaminoethyl)- 2-methylimidazolium trifluoromethanesulfonate ([DAMI][TfO]), 1,3-di(N,Ndimethylaminoethyl)- 2-methylimidazolium bis (trifluoromethylsulfonyl) imide ([DAMI][NTf2]) and 1-butyl-3-methylimidazolium chloride ionic liquids which were synthesized as per the reported procedure.

Results:

We easily developed two types of Ru metal-doped TiO2 nanoparticles using the sol-gel method. After calcination, both Ru@TiO2@IL (3.2 wt% Ru), and Ru@TiO2 (1.7 wt% Ru) materials were characterized by XRD, FTIR, TEM, ICP-AES, EDS, and XANES analysis. After understanding the correct structural arrangement of Ru metal over TiO2 support, we utilized both Ru@TiO2@IL (3.2 wt% Ru) and Ru@TiO2 (1.7 wt% Ru) the materials as a catalyst for direct hydrogenation of CO2 in the presence of water and functionalized [DAMI] [TfO] ionic liquid.

Conclusion:

Here we demonstrated the preparation and characterization of TiO2 supported Ru nanoparticles with and without ionic liquid. After understanding the correct morphology and physiochemical analysis of Ru@TiO2@IL (3.2 wt% Ru), and Ru@TiO2 (1.7 wt% Ru) catalysts, we examined their application in CO2 reduction and formic acid synthesis. During the optimization, we also noticed the significant effect of functionalized [DAMI] [TfO] ionic liquid and water to improve the formic acid yield. Lastly, we also checked the stability of the catalyst by recycling the same till the 7th run.

Acceleration of Baylis-Hillman Reaction using Ionic Liquid Supported Organocatalyst

Background:

Baylis-Hillman reaction requires cheap starting materials, easy reaction protocol, and possibility to create the chiral center in the reaction product has increased the synthetic efficacy of this reaction which also suffers from high catalyst loading, low reaction rate, and poor yield.

Objective:

The extensive use of various functional or non-functional ionic liquids (ILs) with organocatalyst acts not only as reaction medium but also as a support to anchor the catalysts to increase the reaction rate of various organic transformations.

Methods:

In this manuscript, we have demonstrated the synthesis of quinuclidine-supported trimethylamine-based functionalized ionic liquid as a catalyst for the Baylis-Hillman reaction.

Results:

We obtained the Baylis-Hillman adducts in good, isolated yield along with low catalyst loading, short reaction time, wide substrate scope, easy product, and catalyst recycling. N- ((E,3S,4R)-5-benzylidene-tetrahydro-4-hydroxy-6-oxo-2H-pyran-3-yl) palmitamide was also successfully synthesized using CATALYST-3 promoted Baylis-Hillman reaction.

Conclusion:

We successfully isolated the 25 types of Baylis-Hillman adducts using three different quinuclidine-supported ammonium-based ionic liquids such as Et3AmQ][BF4] (CATALYST-1), [Et3AmQ][PF6] (CATALYST-2), and [TMAAmEQ][NTf2](CATALYST-3) as new and efficient catalysts. Generally, all the reactions demonstrated higher activity and gave good to high yield in competition with various previously reported homogenous and heterogeneous catalytic systems. Easy catalyst and product recovery followed by 6 times of catalysts recycling were the added advantages of the prosed catalytic system. Tedious and highly active N-((E,3S,4R)-5-benzylidene-tetrahydro- 4-hydroxy-6-oxo-2H-pyran-3-yl) palmitamide derivative was also synthesized using CATALYST- 3 followed by Baylis-Hillman reaction.

The route towards sustainable production of ethylene glycol from a renewable resource, biodiesel waste: a review

Ethylene glycol (EG) is a commodity chemical commercially produced via oxidation of the petrochemical-based resource, ethylene.

Enhanced Base-Free Formic Acid Production from CO2 on Pd/g-C3 N4 by Tuning of the Carrier Defects

CO₂ hydrogenation is attracting increasing attention as a sustainable route to produce formic acid, a commodity and potential energy vector. Here, bifunctional catalysts comprising metal nanoparticles deposited on bulk graphitic carbon nitride were assessed under base-free conditions, identifying supported Pd as the best performer. The catalyst productivity was enhanced by maximizing the edge-defects of the g-C₃ N₄ carrier, amino groups able to activate CO₂ , and by generating welldispersed 5 nm Pd particles, required to split H₂ . Bottom-up synthesis methods, that is, hard-templating and carbon enrichment upon polymerization, and top-down strategies, that is, thermal exfoliation of the as-prepared solid, were explored to boost the defects, the nature and density of which were evaluated by thermal and (in situ) spectroscopic techniques. After optimization of temperature, pressure, and reaction time, a 20 times higher turnover frequency compared with the best Pd/g-C₃ N₄ catalyst reported producing formic acid from CO₂ without base was attained. This activity level was retained upon recycling with intermediate catalyst regeneration at mild temperature.