Low pressure conversion of CO2 to methanol over Cu/Zn/Al catalysts. The effect of Mg, Ca and Sr as basic promoters. (15th August 2020) - Previtali, D.
Graphical abstract: Highlights: The solubility of MgCO3, CaCO3 and SrCO3 influence catalysts' morphologies. CZA-Ca converts 12% of CO (feed: syngas) at 2 MPa while commercial sample 10%. CZA-Sr resulted inactive towards CO2 conversion into methanol. Abstract: Carbon dioxide concentration level is reaching a non-returning point. Carbon capture technologies are immature and short-term actions are necessary. The conversion of CO2 into methanol is a technical challenge. Commercial copper-zinc-alumina catalysts convert maximum 7% carbon dioxide in syngas at high pressures (5 MPa to 10 MPa) and moderate temperatures (473 K to 573 K) into methanol. However, there are not records on the synthesis of methanol at low pressure ( P < 2.5 MPa ) and without a large excess of hydrogen in the feed. Here, we tested three new catalysts prepared by co-precipitation of copper, zinc and aluminum nitrates (CZA), with strontium, magnesium or calcium as basic promoters to enhance CO2 conversion to methanol. We discussed the microstructure of the catalysts according to the supersaturation of the relative carbonates formed during the co-precipitation synthesis. Compared to the benchmark, the sample doped with Ca showed higher carbon conversion with all the feed compositions tested (syngas, synthetic biosyngas and CO2 with H2 ). CZA doped with Sr is inactive in this reaction.