Advances in joint research between NIRE and RITE for developing a novel technology for methanol synthesis from CO2 and H2

Abstract

NIRE and RITE have jointly performed a national R&D project on methanol synthesis from CO 2 and hydrogen in order to contribute to CO 2 mitigation. In the first step, many attempts were made at developing high-performance catalysts for methanol synthesis. The roles of metal oxides contained in Cu/ZnO-based catalysts were classified into two categories: (1) Al 2 O 3 or ZrO 2 improves the dispersion of copper particles in the catalyst; (2) Ga 2 O 3 or Cr 2 O 3 increases the activity per unit copper surface area of the catalyst. The long-term stability of Cu/ZnO-based catalysts during methanol synthesis from CO 2 and hydrogen was improved by adding a small amount of silica to the catalysts, and then calcining the catalysts at high temperatures around 873 K. Silica added to the catalysts suppressed the crystallization of ZnO contained in the catalysts, which was probably caused by the action of water produced together with methanol. Based on those two important findings, high-performance Cu/ZnObased multicomponent catalysts (SiO 2 ) were developed. The catalysts developed were found to be highly active and extremely stable in methanol synthesis from CO 2 and hydrogen. In the next step, a bench plant with a capacity of 50 kg day À1 of CH 3 OH, which was equipped with facilities for recycling unreacted gases and gaseous products, was successfully operated. The activity of the Cu/ZnO/ZrO 2 / Al 2 O 3 /SiO 2 catalyst was 580 g h À1 of CH 3 OH per liter of catalyst under the reaction conditions of 523 K, 5 MPa and SV = 10,000 h À1 in 1000 h on stream. The selectivity to methanol synthesis was as high as 99.7%, and the purity of crude methanol produced was 99.9 wt%, whereas the purity of crude methanol produced from syngas in a present-day commercial plant was reported as 99.6 wt%.

Development of high performance Cu/ZnO-based catalysts for methanol synthesis and the water-gas shift reaction

“…Our research group studied methanol synthesis from CO 2 and H 2 over Cu/ZnO-based catalysts under a national R&D project entitled ''Fixation and Utilization of Carbon Dioxide by Catalytic Hydrogenation'' [6]. The main purpose of the project is to develop three key technologies required for a proposed system for the conversion/transportation of non-fossil energy combined with catalytic hydrogenation of CO 2 , which is shown in figure 2.…”

“…Proposed system for fixation and utilization of CO 2 by catalytic hydrogenation of (energy conversion/transportation system combined with CO 2 hydrogenation). The route drawn with solid lines emits CO 2 after methanol is used for energy, whereas the route drawn with dotted lines recycles CO 2 after the use of methanol [6].…”

“…On the other hand, the yield of methanol gradually increased with increasing 1/SV until reaction (1) reached equilibrium [6,7]. Figure 4 shows the inhibitory effect of water on methanol synthesis and on CO formation, and also the effect of CO on methanol synthesis.…”

Chemical Recycling of Carbon Dioxide to Methanol and Dimethyl Ether: From Greenhouse Gas to Renewable, Environmentally Carbon Neutral Fuels and Synthetic Hydrocarbons

“…[49][50][51][52] In view of our present understanding of the mechanism of the syngas based chemistry, this is not unexpected. Although still debated, it is now usually accepted that methanol is formed almost exclusively by hydrogenation of CO 2 contained in the syngas on the catalyst's surface.…”

Carbon dioxide capture and utilization in petrochemical industry: potentials and challenges

“…An example is the high performance multicomponent Cu-ZnO-ZrO 2 -Al 2 O 3 -Ga 2 O 3 catalyst prepared by coprecipitation [77]. The addition of a small amount (0.6 wt%) of silica greatly improved the long-term stability of the catalyst [78].…”