Formation of Effective Copper-Based Catalysts of Methanol Synthesis

Steering the Aspects of MgO-Induced Structure Sensitivity in Cu-Based Catalysts for CO2-Rich Syngas Conversion to Dimethyl Ether: Cu/Zn Ratio and Lattice Parameters

“…On the contrary, over our CZM catalyst series, with catalysts having the Cu/Zn molar ratio of >2, a small phase of aurichalcite began to appear, which enhances with a further increase in the Cu/Zn ratio. Our results are well in line with the results reported by Minyukova et al, where they reported the occurrence of a mixed precursor phase (aurichalcite + malachite) at a Cu loading as high as 60–70 mol % and a Cu/Zn ratio within the range of 2–4.6.…”

“…The needles are wellarranged in the pattern similar to "urchin-like" morphology. Catalyst CZ [3]−M(20) possesses well-distributed particles, but the size seems to be bigger than that of CZ [2]−M (20). It is apparent that the dimensions of the particles increased with the increase in the Cu/Zn ratio, in line with the results from XRD (Table S3 of the Supporting Information).…”

“…The degree of reducibility of the calcined catalyst samples was examined by hydrogen-assisted temperature-programmed reduction (H 2 -TPR). No single sharp reduction peak was obtained (Figure 6) for any of the catalyst samples, except for CZ [2]−M (20). Reasons might include the reduction of CuO in manifold steps, 45 the reduction of several CuO species, e.g., from diverse precursor phases, 46 or the successive reduction of components present in the catalyst other than CuO.…”

“…The non-appearance of standard reflections related to MgO at 2θ = 37.5°and 43.0°m ight be accredited to its amorphous character. As a result of the homogeneous metal distribution in the precursor, a decent dispersion of the mixture of CuO and ZnO has been achieved in catalysts CZ [2]−M (20) and CZ [3]−M(20) because many ZnO peaks were found to be overlapped. However, the same can be observed for catalyst CZ [4]−M(20), but the reason for this might be the presence of more Cu in the catalyst.…”

“…This totally depends upon the nominal metal composition used for synthesizing the precursor. With Cu being the major fraction, these precursor phases , are markedly Cu 2 (OH) 2 CO 3 (malachite) for pure Cu samples, (Cu 1– y Zn y ) 5 (OH) 6 (CO 3 ) 2 (aurichalcite) with y > 0.5, (Cu 1– x Zn x ) 2 (OH) 2 CO 3 (zincian malachite) with x < 0.3, and (Cu,Zn) 6 Al 2 (OH) 16 CO 3 ·4H 2 O (hydrotalcite-like phase), exceptionally when a considerable amount of Al 3+ is present.…”