Ni-MoOx bifunctional catalyst on SiO2 for vapor halide-free methanol carbonylation: Insight into synergistic catalysis between Ni and MoOx

Cu/Sn-β Catalyst Enabling the One-Step Synthesis of Methyl Acetate from Methanol Alone via Dehydrogenation Coupling

“…It is not surprising because the dehydration of methanol to DME is a second-order reaction to methanol. 15,16 Moreover, the STY DME also shows a positive correlation with the medium−strong LAS density (Figure 5C). As widely accepted, moreover, Cu 0 is the active phase for the methanol to MF reaction.…”

“…In Figure B, the space–time yield of DME (STY DME ) was plotted against the weak LAS density of the 1Cu/Sn-β- x ( x = 120, 100, 80, 60, 30) catalysts, showing a clear positive-quadratic correlation. It is not surprising because the dehydration of methanol to DME is a second-order reaction to methanol. , Moreover, the STY DME also shows a positive correlation with the medium–strong LAS density (Figure C). As widely accepted, moreover, Cu 0 is the active phase for the methanol to MF reaction. , Combining the above information with the fact that our Sn-free 1Cu/Sn-β-∞ (active for methanol-to-MF) and Cu-free Sn-β-100 (active for methanol-to-DME) are completely inert for the title reaction (Figure A,B), we believe that the Cu δ+ (0 < δ ≤ 1; medium–strong LAS) coupling with framework-confined Sn (weak LAS) toward synergistic catalysis is the only possibility, which is closely linked with the formation of target product MA (Figure D,E).…”

“…On combining this information with the common knowledge that the acid site density and distribution can also influence the methanol conversion pathway over the catalyst, we cannot conclude that the LAS of our Cu/Sn-β plays a key role in converting methanol to only DME. For instance, the presence of continuous weak acid sites can accelerate the methanol dehydration to form DME, , while the strong acid sites are highly active for further converting methanol and/or DME to hydrocarbons ( i.e. , MTH reaction). ,, Therefore, the acidity of such used 1Cu/Sn-β- x ( x = 120, 100, 80, 60, 30) catalysts were measured by NH 3 -TPD as well as 1Cu/Sn-β-∞ and Sn-β-∞ as references, with the results shown in Figure .…”

“…For instance, the presence of continuous weak acid sites can accelerate the methanol dehydration to form DME, , while the strong acid sites are highly active for further converting methanol and/or DME to hydrocarbons ( i.e. , MTH reaction). ,, Therefore, the acidity of such used 1Cu/Sn-β- x ( x = 120, 100, 80, 60, 30) catalysts were measured by NH 3 -TPD as well as 1Cu/Sn-β-∞ and Sn-β-∞ as references, with the results shown in Figure . Clearly, the desorbed NH 3 signals in the NH 3 -TPD-MS profiles are all detected at 50–500 °C (Figure A).…”

“…Furthermore, using highly toxic iodine promoters and carbon monoxide does not conform to the development concept of green chemistry. Therefore, a large number of heterogeneous carbonylation catalysts without iodine promoters have been developed, such as NiCl 2 -CuCl 2 /activated carbon, zeolites, − and TMO/SiO 2 (TMO: transition-metal oxides). , Most of them are far inferior to industrial catalysts. Recently, an atomically dispersed Rh-ReO 4 /SiO 2 catalyst was reported, achieving an acetic acid production rate comparable to that of the homogeneous Monsanto process …”