Mechanistic aspects of a homogeneous carbon monoxide hydrogenation catalyst - tetrairidium dodecacarbonyl in molten aluminum chloride-sodium chloride

Hydrogenation of Carbon Dioxide to C2–C4 Hydrocarbons Catalyzed by Pd(PtBu3)2–FeCl2 with Ionic Liquid as Cocatalyst

“…The combination of [BMIm][PF 6 ]) with Xantphose ndowed the Pd-Fe catalysts with the ability of activating CO 2 and H 2 simultaneously via [HPd(PtBu 3 )(BMIm-COO)(BMIm)(PF 6 )Fe] + species, thus catalyzing the formationo fC 2 -C 4 hydrocarbonst hrough CO 2 hydrogenation. Herein,ahomogeneousc atalytic system was developed composed of the ionic liquid 1-butyl-3methylimidazolium hexafluorophosphate ([BMIm][PF 6 ]), Pd(PtBu 3 ) 2 ,F eCl 2 ,a nd the ligand 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos) for hydrogenation of CO 2 under mild conditions, which resultedi nC 2 -C 4 hydrocarbons in selectivities up to 98.3 C-mol %a t1 80 8C.…”

“…[4b, d-f] Co-Fe bimetallic catalysts could catalyzet he reaction at lower temperature( e.g.,2 70 8C), achieving C 2 + selectivity up to 69 %. [6] Ir 4 (CO) 12 was reported to be capable of catalyzing the hydrogenationo fC Oi nto methane,e thane, and trace amountso fp ropane and isobutene in am olten NaCl-2AlCl 3 mixture, and AlCl 3 was found to promote the carbonchain growth through catalyzing the formation of CH 3 Cl and CH 3 CH 2 Cl intermediates. [5] To date, there is no report on the CO 2 hydrogenation to C 2 -C 4 hydrocarbonso ver homogeneous catalysts in the literature.T he hydrogenation of carbon monoxide (CO) to light hydrocarbons has been widely investigated with homogeneous and heterogeneous catalysts.…”

“…[5, 8c] Herein, we report the IL-promoted CO 2 hydrogenation to C 2 -C 4 hydrocarbonso verP d(PtBu 3 ) 2 -FeCl 2 homogeneous catalysts in the presence of al igand, 4,5-bis(diphenylphosphino)-9,9-dimethylxanthene (Xantphos)a tr elativelyl ow temperature (Scheme 1). [ 6 ]c an cause the water formed in the reduction of CO 2 to be expelled from the catalytically active sites, which may be favorable to the CÀC coupling to form C 2 + products. [4] In addition, the catalytic system wasstable and reusable.…”

“…However,n op roduct waso btained (Table 1, entry 5), indicating that DMI inhibited the catalytic activity of the Pd-Fe catalyst in this reactions ystem. Although [EMIm][PF 6 ]w as effectivef or CO 2 hydrogenation, the yield and the selectivity towards C 2 -C 4 hydrocarbonsw ere much lower than those achieved in [BMIm] [PF 6 ]. The above resultsi ndicated that the cooperation of cation and anion of the IL was responsible for their activity to promoteCO 2 hydrogenationtoC 2 -C 4 hydrocarbons.…”

“…6 ]( denoted as Pd-L-Fe-F) were examined by means of X-ray photoelectron spectroscopy (XPS).I nt he Pd 3d spectrum of Pd(PtBu 3 ) 2 ( Figure S8 ai nt he Supporting Information), two pairs of peaks with binding energies (BEs) at 335.24a nd 340.49 as well as 337.19 and 342.38 eV were assigned to Pd 0 and Pd 2 + ,r espectively. 6 ]( denoted as Pd-L-Fe-F) were examined by means of X-ray photoelectron spectroscopy (XPS).I nt he Pd 3d spectrum of Pd(PtBu 3 ) 2 ( Figure S8 ai nt he Supporting Information), two pairs of peaks with binding energies (BEs) at 335.24a nd 340.49 as well as 337.19 and 342.38 eV were assigned to Pd 0 and Pd 2 + ,r espectively.…”