Within this project, Fraunhofer CBP is working on the further development of methanol synthesis from CO2‑rich synthesis gas, first on a laboratory scale (TRL 3) and further scaled‑up to a pilot plant (TRL 6). The integration of the Co‑SOEC process with the methanol pilot plant will be carried out and its technological feasibility tested. Sample quantities of up to 500 liters are to be made available for application testing.
Producing methanol from synthesis gas
Once a methanol plant had been engineered and set up on a laboratory scale at the CBP, the temperature (250–270°C), pressure (50–90 bar gauge) and gas hourly space velocity (GHSV; 8,000–30,000 h-1) were varied to determine the optimum process parameters while using an industrial catalyst.
During this process, the synthesis gas was converted into a methanol-water mixture using a plug flow reactor and an industrial catalyst. Any non-converted synthesis gas was separated by a separator and fed back to the reactant flow. As the process parameters were varied, their influence on the conversion process was examined, long-term tests were carried out in relation to catalyst stability and the results of the experiments were compared with the simulations that were being conducted in parallel with the process.
The results of the experiments demonstrated that the conversion rate could be increased by up to 44 percent by raising the pressure. By contrast, increasing the GHSV led to a reduction in the conversion rate. This can be explained by the shorter contact time with the catalyst. Within the investigated temperature range, the temperature was not found to have any influence on the conversion rate. The results from the simulations were comparable to those from the laboratory-scale experiments.
Piloting the methanol process
Once methanol synthesis had been established on a laboratory scale, a pilot plant was converted to carry out the methanol process on a pilot-plant scale and then put into operation. The operating point was scaled to the highest conversion rate and the plant was operated on a long-term basis with subsequent rectification of the methanol-water mixture. The conversion rate and purity of the methanol produced in the pilot plant were similar to those achieved in the laboratory experiment.
For the subsequent practical application tests on the cars and trucks, the methanol produced from the synthesis gas was used as a fuel in both blended and pure form. Given that no standard has yet been drawn up for using methanol as a fuel, possible requirements for the product were defined on the basis of DIN 51625 “Automotive fuels – Ethanol fuel – Requirements and test methods”.
Methanol synthesis on behalf of customers
Following the successful completion of the project, Fraunhofer CBP now has the expertise required to carry out methanol synthesis on behalf of interested companies and organizations on both a laboratory and a pilot scale.