Advances in joint research between NIRE and RITE for developing a novel technology for methanol synthesis from CO2 and H-2

NIRE and RITE have jointly performed a national R&D project on methanol syn thesis from CO2 and hydrogen in order to contribute to CO2 mitigation. In t he first step, many attempts were made at developing high-performance catal ysts for methanol synthesis. The roles of metal oxides contained in Cu/ZnO- based catalysts were classified into two categories: (1) Al2O3 Or ZrO2 impr oves the dispersion of copper particles in the catalyst; (2) Ga2O3 or Cr2O3 increases the activity per unit copper surface area of the catalyst. The l ong-term stability of Cu/ZnO-based catalysts during methanol synthesis from CO2 and hydrogen was improved by adding a small amount of silica to the ca talysts, and then calcining the catalysts at high temperatures around 873 K , Silica added to the catalysts suppressed the crystallization of ZnO conta ined in the catalysts, which was probably caused by the action of water pro duced together with methanol, Based on those two important findings, high-p erformance Cu/ZnO-based multicomponent catalysts (Cu/ZnO/ZrO2/ Al2O3/SiO2 a nd Cu/ZnO/ZrO2/Al2O3/Ga2O3/ SiO2) were developed, The catalysts developed w ere found to be highly active and extremely stable in methanol synthesis fr om CO2 and hydrogen. In the next step, a bench plant with a capacity of 50 kg day(-1) of CH3OH, which was equipped with facilities for recycling unrea cted gases and gaseous products, was successfully operated. The activity of the Cu/ZnO/ZrO2/ Al2O3/SiO2 catalyst was 580 g h(-1) of CH3OH per liter of catalyst under the reaction conditions of 523 K, 5 MPa and SV = 10,000 h(- 1) in 1000 h on stream. The selectivity to methanol synthesis was as high a s 99.7%, and the purity of crude methanol produced was 99.9 wt%, whereas th e purity of crude methanol produced from syngas in a present-day commercial plant was reported as 99.6 wt%, Copyright (C) 2000 John Wiley & Sons, Ltd.