We have developed a Keggin polyoxometalate (POM)‐based ionic‐liquid (IL)‐immobilizing rhodium single‐atom Rh catalyst (MTOA)5[SiW11O39Rh] (MOTA=methyltrioctylammonium cation) that can afford exceptionally high catalytic activity for the hydroformylation of alkenes to produce aldehydes at an ultralow loading of Rh (ca. 3 ppm). For styrene hydroformylation, both the conversion and the yield of the aldehyde can reach almost 99 %, and a TOF as high as 9000 h−1 was obtained without using any phosphine ligand in the reaction process. Further characterization by FTIR, ICP and ESI‐MS analysis revealed that the single Rh atom was incorporated in the lacunary POM anions. In particular, the bulky IL cation can play an additional role in stabilizing Rh species and thus prevent aggregation and leaching of Rh species. The IL catalyst was miscible with n‐hexane at temperatures; this contributed to exceptionally high activity for hydroformylation even at ultra‐low loading of IL catalyst.

In this work, we have developed a Ru single-atom substituted polyoxometalate-based ionic liquid ([TOMA6SiW11O39Ru(dmso)], TOMA = methyltrioctylammonium, named as Ru-POM-IL) and confirmed that the single-atom Ru is anchored into the framework of the POM. The binary ionic liquid (IL) system, composed of the POM-based IL and 1-butyl-3-methyl-imidazolium acetate (BMImOAc), exhibits high efficiency for N-formylation of amines with CO2 and H2, leading to formylamides with high yields in toluene-IL biphasic media. The characterization by laser confocal scanning microscopy reveals a specific sponge-like structure of the binary IL, facilitating the efficient contact between the catalytic active sites and the substrate molecules. Detailed investigations elucidate that the reaction proceeds via a pathway with formate intermediates, including CO2 adsorption and activation by BMImOAc, morpholine-assisted heterolytic splitting of H2 into Ru–Hδ‑ species and the Hδ+ attachment to the morpholine N center; the coupling of CO2 with Ru–Hδ‑ to afford formate species; and then the dehydration of the formate intermediates to formamides. The catalytic system exhibits offered advantages of high efficiency, robustness, and recyclability in the N-formylation reaction.

Catalytic hydrogenations represent fundamental processes in the synthesis of fine chemicals and chemical intermediates, allowing for atom-efficient and clean functional group transformations. Herein, we have developed a highly efficient, robust catalytic system consisting of a ruthenium hydride complex [RuH­(CO)­(dppp)­(en)]Cl and tetrabutylammonium acetate (TBAOAc), where the former was employed as a catalyst for selective hydrogenation of methyl levulinate (ML) to γ-valerolactone (GVL) with molecular hydrogen under mild reaction conditions without any base additives, while the latter was used as a low-temperature molten salt solvent assisting the hydrogenation reaction. After the reaction, solid salt TBAOAc can settle down spontaneously due to the immiscibility with weak polar extraction solvent, leading to the clean separation of products from reaction mixture. Furthermore, the catalytic system was highly leaching-resistant and maintains its catalytic activity in the consecutive recycles. Notably, TBAOAc not only acted as reaction media but also played an important role in improving the catalytic performance via the coordination of OAc– with Ru sites. In contrast to poor activity of ML hydrogenation catalyzed by Ru complex in conventional organic solvents, the superior catalytic activity was achieved by using TBAOAc as media. NMR, HR-ESI-MS analysis, and deuterium-labeling studies indicated that the ligand exchange could happen between TBAOAc and the ruthenium hydride complex via the formation of Ru–OAc species, which can promote H2 activation, dissociation and sequential hydrogenation. Finally, this catalytic system has been extended smoothly for N-formylation of a large variety of amines with carbon dioxide and hydrogen and showed high catalytic activity, stability, and selectivity toward formamides. This study identifies the reason for TBAOAc-assisted ruthenium complex catalyzing hydrogenation and provides new insights to optimize the sustainability of a procedure for the conversion of biomass-derived platform molecules and CO2.

In this work, the zirconium phosphate (ZrP) supported Ag nanoparticles (NPs) catalysts have been constructed. The as-obtained catalyst was characterized thoroughly by XRD, HAADF-STEM and py-IR etc. The coordination interaction...

In this work, zirconium-phosphate-supported platinum catalysts have been prepared by a wetness impregnation method and characterized thoroughly by various methods. The 1% Pt/ZrP catalyst displayed superior catalytic performance for the selective hydrogenation of nitrobenzene. It was found that the formation rate of para-aminophenol was much higher than that of aniline over the catalyst in the presence of inorganic acid and DMSO. A full conversion of nitrobenzene and high selectivity to para-aminophenol (89%) were achieved under mild reaction conditions (80 °C, 0.6 MPa H 2 ). Also, the catalyst can be recycled in 14 consecutive catalytic runs without any obvious decrease in activity and selectivity for the hydrogenation of nitrobenzene. The electron transfer interaction of Pt(0) species with zirconium phosphate accounted for the high dispersion and leaching resistance of the Pt sites, leading to excellent recyclability of the catalysts. The further characterization by in situ DRIFT demonstrated that the nitro functional group was dominantly adsorbed on acid sites of zirconium phosphate and reduced to N-phenylhydroxylamine by spillover hydrogen, followed by rearrangement to afford paraaminophenol.