Abstract
Ternary CuxZnyAlz catalysts were prepared using the hydrotalcite (HT) method. The influence of the atomic x:y:z ratio on the physico-chemical and catalytic properties under CO2 hydrogenation conditions was probed. The characterization data of the investigated catalysts were obtained by XRF, XRD, BET, TPR, CO2-TPD, N2O chemisorption, SEM, and TEM techniques. In the “dried” catalyst, the typical structure of a hydrotalcite phase was observed. Although the calcination and subsequent reduction treatments determined a clear loss of the hydrotalcite structure, the pristine phase addressed the achievement of peculiar physico-chemical properties, also affecting the catalytic activity. Textural and surface effects induced by the zinc concentration conferred a very interesting catalyst performance, with a methanol space time yield (STY) higher than that of commercial systems operated under the same experimental conditions. The peculiar behavior of the hydrotalcite-like samples was related to a high dispersion of the active phase, with metallic copper sites homogeneously distributed among the oxide species, thereby ensuring a suitable activation of H2 and CO2 reactants for a superior methanol production.
Highlights
Methanol is usually produced from synthesis gas mixtures (COx /H2 ) at typical reaction conditions of 230–280 ◦ C and 50–100 bar over Cu–based catalysts
Considerable attention was recently paid to hydrotalcite-like compounds (HT) as catalyst precursors, because the catalyst systems derived from hydrotalcite structures possess homogeneous dispersion of metal cations at an atomic level, high stability against sintering, high specific surface area, and strongly basic properties [18,19,20]
The catalytic behavior of the prepared samples was investigated under CO2 hydrogenation conditions and, in Table 4, the results obtained at 30 bar in the temperature range of 220–260 ◦ C are reported, in terms of carbon dioxide conversion, methanol selectivity, and methanol yield
Summary
Methanol is usually produced from synthesis gas mixtures (COx /H2 ) at typical reaction conditions of 230–280 ◦ C and 50–100 bar over Cu–based catalysts In this industrial process, a Cu-based catalyst is typically used, with the composition completed by Zn and Al components [1,2]. Appropriate adsorption amount and adsorption strength of CO2 are beneficial for the production of methanol, which give a guideline for the design of highly effective and efficient catalysts On this account, considerable attention was recently paid to hydrotalcite-like compounds (HT) as catalyst precursors, because the catalyst systems derived from hydrotalcite structures possess homogeneous dispersion of metal cations at an atomic level, high stability against sintering, high specific surface area, and strongly basic properties [18,19,20]. Irrespective of the extent of crystallinity of the coprecipitated phase, the influence of the Cu:Zn:Al ratio on the formation of well-dispersed and active metal particles, generated after calcination and reduction, was addressed
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