Low pressure conversion of CO2 to methanol over Cu/Zn/Al catalysts. The effect of Mg, Ca and Sr as basic promoters

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 CO 2 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 CO 2 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 CO 2 with H 2 ). CZA doped with Sr is inactive in this reaction.

Century of Technology Trends in Methanol Synthesis: Any Need for Kinetics Refitting?

“…However, in these conditions, the selectivity toward high-carbon-content side products is lower . Commercial catalysts are based on Cu/ZnO/Al 2 O 3 (CZA catalyst), , where copper is essential to promote the shift reaction, changing the relative ratio among CO, CO 2 , and H 2 . The catalyst composition varies according to the producer; generally, copper ranges in weight between 20 and 80%, zinc oxide from 15 up to 50%, and the Al 2 O 3 content varies from 4 to 30% .…”

Comparative study on the effect of different copper loading on catalytic behaviors and activity of Cu/ZnO/Al2O3 catalysts toward CO and CO2 hydrogenation

“…Both CO and CO 2 conversions over the CZA-L and CZA-H catalysts are relatively low compared to other researches. Previously, some researchers studied on CO and CO 2 hydrogenation reaction at medium to high pressure (over 2 MPa) and they reported the CO conversion in the range of 5-12%, depending on pressure and temperature of reaction (Previtali et al, 2020;Sadeghinia et al, 2020). In case of CO 2 hydrogenation, they reported the conversion of CO 2 under moderate pressure (over 5 MPa) that is around 7-16% (Sun et al, 2015;Sadeghinia et al, 2020).…”

“…The greenhouse gas such as CO 2 is the main environmental pollution for global warming. This problem leads to the utilization of carbonaceous feedstocks (CO and CO 2 ) in efficient ways to convert them into more valuable chemical products (Allam et al, 2019;Previtali et al, 2020). Hence, the study of high value-added products from the conversion of CO and CO 2 is interesting, especially on hydrogenation (Hu et al, 2018;Li et al, 2020).…”

Experimental methods in chemical engineering: Process simulation

“…Process simulation discriminates between process alternatives (design: 246 articles), which comprises modelling (187 articles) and determines the dimensions of unit operations like separation (126), including distillation (137 articles) (reactive and extractive), heat integration (33), and dehydration (26). Hung et al, [27] for example, demonstrated that recovering dilute acetic acid water solutions (between 30-70% by mass of acid) with amyl alcohols among C 1 -C 5 minimizes the total annual cost (TAC), without any stream pretreatment.…”

“…This is because first-and second-generation biofuels interest has been dropping in recent years in favour of other green technologies for the conversion of green house gases, such as CO 2 into fuels. [31][32][33] In fact, the magenta cluster centered around H 2 (227 articles) concentrates on gasification (biomass +steam with 239 articles), syngas (141), and reactors and fluidized beds (84). CO 2 capture (193 articles), with CO 2 (162), and CH 4 dominate the yellow cluster that includes combustion (87), absorption (82), and HYSYS (66).…”