The role of the acidity of alumina prepared by aluminum-carbon black composite for CO hydrogenation to dimethyl ether on hybrid Cu–ZnO–Al2O3/alumina

Abstract

The effects of surface area and the acidity of mesoporous c-Al 2 O 3 , which is prepared by calcining aluminum-carbon black composite (Al/CB) of the precipitated aluminum nitrate on carbon black at different weight ratios, were investigated to verify the roles of carbon black in the surface properties and stability of Cu-ZnO-Al 2 O 3 for the direct synthesis of dimethyl ether (DME) from syngas. A high surface area of *100 m 2 /g with a large pore diameter of *25 nm originated from the occupied spaces of carbon black enhanced the dispersion of the active Cu-ZnO-Al 2 O 3 particles by forming a strong and stable interaction with mesoporous solid acid c-Al 2 O 3 surfaces. The enhanced dispersion of copper-containing particles, being strongly interacted with the acid sites of the hybrid Cu-ZnO-Al 2 O 3 / Al 2 O 3 catalyst using c-Al 2 O 3 prepared at an optimal Al/CB weight ratio of 10, is mainly responsible for the high CO conversion with a high yield to oxygenates and a suppressed aggregation of active copper species during the direct synthesis of DME from syngas.Keywords Dimethyl ether (DME) Á Syngas Á Cu-ZnO-Al 2 O 3 Á Hybrid catalyst Á Composite of carbon black and alumina Á Acid sites Electronic supplementary material The online version of this article (

Morphology Effects of Ferrierite on Bifunctional Cu–ZnO–Al2O3/Ferrierite for Direct Syngas Conversion to Dimethyl Ether

“…Since the dispersion and grain size of the Cu–ZnO–Al 2 O 3 particles on the different morphologies of the FERs can largely change the reducibility of Cu crystallites, the reduction behaviors of CZA-incorporated FERs were measured by two successive TPR analysis and the reduction patterns are displayed in Figure A and summarized in Table S2. Based on the first TPR run, the maximum reduction temperatures on the CZA-incorporated FERs were found to be 208–214 °C with the minimum temperature on the CZA/NSFER by showing a typical Gaussian pattern due to the homogeneous size distribution of Cu–ZnO–Al 2 O 3 particles, which are similar with the previous reports. , Interestingly, the high-temperature reduction peaks at ∼ 300 °C observed on the CZA/m-FER and CZA/CFER could be assigned to the strongly interacted and hardly reducible CuO segregates on the much stronger acidic sites of the FERs . The successive second TPR run after the oxidation of the reduced CZA-incorporated FERs by the first TPR run revealed a slight increase of reduction temperatures up to 215–230 °C, which can be caused by thermal aggregations of Cu crystallites with their adjusted interactions in the segregated Cu–ZnO–Al 2 O 3 matrices by selectively eliminating high-temperature reduction peaks at ∼300 °C on the CZA/m-FER and CZA/CFER.…”

“…homogeneous size distribution of Cu−ZnO−Al 2 O 3 particles, which are similar with the previous reports. 30,31 Interestingly, the high-temperature reduction peaks at ∼ 300 °C observed on the CZA/m-FER and CZA/CFER could be assigned to the strongly interacted and hardly reducible CuO segregates on the much stronger acidic sites of the FERs. 32 The successive second TPR run after the oxidation of the reduced CZAincorporated FERs by the first TPR run revealed a slight increase of reduction temperatures up to 215−230 °C, which can be caused by thermal aggregations of Cu crystallites with their adjusted interactions in the segregated Cu−ZnO−Al 2 O 3 matrices by selectively eliminating high-temperature reduction peaks at ∼300 °C on the CZA/m-FER and CZA/CFER.…”

Mesostructured γ-Al2O3-Based Bifunctional Catalysts for Direct Synthesis of Dimethyl Ether from CO2

“…γ-Al 2 O 3 , the focus of this work, is widely used as a methanol dehydration catalyst due to its low cost, compared to zeolites and other aluminosilicates, and due to the presence of Lewis acid sites of moderate strength, which lead to high DME selectivity; the presence of strong Brønsted sites, on the other hand, despite showing a higher activity in methanol dehydration, gives rise to a lower selectivity, due to the formation of hydrocarbons through the Methanol-To-Olefins (MTO) process and a potential deactivation of the catalyst due to coke formation [10,[16][17][18]. For these reasons, γ-Al 2 O 3 has been widely reported for the methanol-to-DME process [19][20][21], as well as for the one-pot syngas-to-DME [22][23][24] and CO 2 -to-DME processes [25][26][27].…”