CO2 Hydrogenation to Methanol by a Liquid-Phase Process with Alcoholic Solvents: A Techno-Economic Analysis

Abstract

Synthesis of methanol from recirculated CO2 and H2 produced by water electrolysis allows sustainable production of fuels and chemical storage of energy. Production of renewable methanol has, however, not achieved commercial breakthrough, and novel methods to improve economic feasibility are needed. One possibility is to alter the reaction route to methanol using catalytic alcoholic solvents, which makes the process possible at lower reaction temperatures. To estimate the techno-economic potential of this approach, the feasibilities of the conventional gas-phase process and an alternative liquid-phase process employing 2-butanol or 1-butanol solvents were compared by means of flowsheet modelling and economic analysis. As a result, it was found that despite improved methanol yield, the presence of solvent adds complexity to the process and increases separation costs due to the high volatility of the alcohols and formation of azeotropes. Hydrogen, produced from wind electricity, was the major cost in all processes. The higher cost of the present, non-optimized liquid-phase process is largely explained by the heat required in separation. If this heat could be provided by heat integration, the resulting production costs approach the costs of the gas-phase process. It is concluded that the novel reaction route provides promising possibilities, but new breakthroughs in process synthesis, integration, optimization, and catalysis are needed before the alcoholic solvent approach surpasses the traditional gas-phase process.

Using renewable methanol, PEM fuel cells and on-board carbon capture to reduce well-to-propeller ship emissions

“…CO 2 + H 2 ⇆ CO + H 2 O (5) CO + 2H 2 ⇆ CH 3 OH (6) Looking at these reaction equations, it is clear that not all CO2 is converted to methanol. A standard CO2 hydrogenation process yield factor is 0.81 (Nieminen et al, 2019), which is defined as the ratio between actual production and theoretical maximum production if all CO2 could be converted to methanol. Following this ratio, approximately 0.59 tonnes of methanol can be made from every tonne of CO2.…”

“…Figure 3: Different pathways to produce renewable methanol Regardless of the source of CO2, CO2 hydrogenation involves the following main chemical reaction: CO 2 + 3H 2 ⇆ CH 3 OH + H 2 O (4) Two side reactions also occur, the reverse water gas shift (RWGS) reaction and hydrogenation of carbon monoxide (B. Lee et al, 2020):CO 2 + H 2 ⇆ CO + H 2 O (5) CO + 2H 2 ⇆ CH 3 OH (6) Looking at these reaction equations, it is clear that not all CO2 is converted to methanol. A standard CO2 hydrogenation process yield factor is 0.81(Nieminen et al, 2019), which is defined as the ratio between actual production and theoretical maximum production if all CO2 could be converted to methanol. Following this ratio, approximately 0.59 tonnes of methanol can be made from every tonne of CO2.…”

Techno-Economic Assessment of Green H2 Carrier Supply Chains

“…Recent advances in green formic acid technology, such as the electrochemical reduction of CO 2 to formic acid and biogenic formic acid production, encourage its use as a sustainable hydrogen carrier. − The goal of this work was to identify the most cost-effective green hydrogen carrier by considering the entire supply chain of hydrogen delivery. The production costs of green hydrogen and potential green hydrogen carriers have been explored in other work. − However, the costs associated with the entire supply chain of delivering green hydrogen to distributed consumers have been often neglected. Here, we sought to systematically estimate the costs along the entire supply chain, from production to end use, associated with the most promising green hydrogen carriers (including formic acid) and molecular green hydrogen.…”

Hydrogenation of carbon dioxide (CO2) to fuels in microreactors: a review of set-ups and value-added chemicals production

“…Two technologies, carbon capture and storage (CCS) and carbon capture and utilization (CCU), play a significant role in reducing CO 2 emissions. 4 Generating value added products through CO 2 hydrogenation utilising renewable hydrogen (H 2 ), produced by water electrolysis, 5 has proven to be a major challenge in order to seek alternative fuel synthesis routes. 6 CCS is expected to play a vital role in limiting the GHGs emissions, as well as climate change attenuation in the future.…”