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Since the earliest reports on catalytic benzene hydrogenation, 1,3-cyclohexadiene and cyclohexene have been proposed as key intermediates. However, the former has never been obtained with remarkable selectivity. Herein, we report the first partial hydrogenation of benzene towards 1,3-cyclohexadiene under mild conditions in a catalytic biphasic system consisting of Ru@Pt nanoparticles (NPs) in ionic liquid (IL). The tandem reduction of [Ru(COD)(2-methylallyl)2] (COD=1,5-cyclooctadiene) followed by decomposition of [Pt2(dba)3] (dba=dibenzylideneacetone) in 1- n-butyl-3-methylimidazolium hexafluorophosphate (BMI ⋅PF6) IL under hydrogen affords core-shell Ru@Pt NPs of 2.9±0.2 nm. The hydrogenation of benzene (60 °C, 6 bar of H2) dissolved in n-heptane by these bimetallic NPs in BMI ⋅PF6 affords 1,3-cyclohexadiene with an unprecedented 21 % selectivity at 5 % benzene conversion. Conversely, almost no 1,3-cyclohexadiene was observed when using monometallic Pt0 or Ru0 NPs under the same reaction conditions and benzene conversions. This study reveals that the selectivity is related to synergetic effects of the bimetallic composition of the catalyst material as well as to the performance under biphasic reaction conditions. It is proposed that colloidal metal catalysts in ILs and under multiphase conditions ('dynamic asymmetric mixtures') can operate far from the thermodynamic equilibrium akin to chemically active membranes. [ABSTRACT FROM AUTHOR]

The reduction of atmospheric CO 2 is indeed a major challenge for modern life due to its increase as a result of the intensified contemporary industrial activities and its contribution to global warming. One of the most desirable approaches to accomplish this goal is to convert CO 2 into C1 feedstocks, such as formic acid (FA). In this regard, naked ruthenium clusters and nanoparticles (1.8 ± 0.3 nm) are prepared by magnetron sputtering into different supported ionic liquid phases (SILPs) that demonstrated remarkable efficiency in producing a total of 2.2 M of free FA with a TONs of 7305 in 1-Butyl-3-methylimidazolium acetate ionic liquid media at 87 °C. The higher efficiently is related to the hydrophobic/hydrophilic effect presents in the ionic liquid-cages of the SILPs akin to the micelle nano (micro)reactors, which act as catalytic membranes enabling the tuning of FA production. DFT calculations support the mechanistic approach followed the hydrogenation of HCO 3 * to FA. [Display omitted] • Ru clusters and NPs are prepared by magnetron sputtering into different SiO 2 supported ionic liquid phases (SILPs). • The presence of IL-anions (BF 4 and NTf 2) significantly control the selective growth of Ru atoms to clusters and NPs. • Ru clusters are formed in the SILP containing BF 4 - anion while small NPs (1.8±0.3 nm) are obtained having NTf 2 - anion. • Ru clusters/SILP-BF 4 catalyst demonstrates remarkable efficiency in producing a total of 2.2 M of free FA in BMIm.OAc IL. • It is proposed that FA originates from the hydrogenation of HCO 3 - rather than the direct hydrogenation of the CO 2. [ABSTRACT FROM AUTHOR]

• Bimetallic core-shell Ni-Ru NPs were prepared in BMI.NTf 2 ionic liquid. • hydrophobic ionic liquid affords mainly C 2 + hydrocarbons. • Ru-Ni NPs in hydrophilic ionic liquid gives CO during CO 2 hydrogenation. • Positive catalytic synergistic effect is observed. • Metal segregation was observed experimentally during the catalysis. The direct conversion of carbon dioxide to hydrocarbons is one of the key solutions to both the reduction of the greenhouse effect and the sustainable production of fuels and lubricants. Here, it is demonstrated that simple bimetallic Ru/Ni nanoparticles (NPs) (2–3 nm, Ru-rich shell, and Ni-rich core) in a hydrophobic ionic liquid (IL) promote the direct hydrogenation of CO 2 to light hydrocarbons (HCs) under very mild reaction conditions in a simple batch reactor. The reaction of CO 2 with hydrogen (1:4, 8.5 bar) at 150 °C with the Ru/Ni NPs (3:2) in bis((trifluoromethyl)sulfonyl)amide (BMI.NTf 2) hydrophobic IL affords C 2 + hydrocarbons (79% alkanes and 16% olefins) with 5% CH 4 at 30% conversion. However, the reaction performed in the hydrophilic IL 1- n -butyl-3-methyl-1 H -imidazol-3-ium tetrafluoroborate affords mainly CO. The catalytic hydrogenation of CO 2 towards HCs proceeds by a two-step process with the initial conversion of CO 2 into CO by reverse gas shift reaction (RWGS), followed by Fischer-Tropsch Synthesis (FTS). The bimetallic NPs have higher catalytic efficiencies than their monometallic counter- parts, owing to strong synergy between the metals. The presence of Ni in the bimetallic NPs yields a more active RWGS catalyst, and the Ru increases the FTS towards heavier HCs. [ABSTRACT FROM AUTHOR]