Using CO2 to generate synthesis gas

In the pilot plant, the reformer’s reactor tube is dimensioned and designed to correspond to the later, industrially usable variant. In commercial plants, the necessary production capacity is achieved through using a corresponding number of reformer tubes. This makes it possible to test new processes and materials under practical conditions. The reformer in the pilot plant is also equipped with extensive measuring technology. This enables the scientists to document and evaluate operating parameters and gas compositions that can be set over a wide range of values.

For the new Dryref process, the scientists have significantly changed standard steam reforming. In addition to methane and some water vapour, CO₂ is also fed into the tubular reactor at high pressure. At temperatures between 800 and 1000 °C, the CO₂ reacts with the methane to form hydrogen and carbon monoxide (CO). This process is more energy-efficient than the standard version: firstly, the dry reforming technique requires much less water vapour to prevent catalyst coking; secondly, the syngas is produced under high pressure, which eliminates the need for prior gas expansion and, following the reaction, further compression. A further advantage is the use of large amounts of CO₂. This is a waste product in power plants and industrial processes. CO-rich synthesis gases are an important synthetic building block in the chemical industry. These are used, for example, in hydroformylation and carbonylation reactions. This makes them the starting point for numerous products such as fertilisers and fuels.

The Dryref process produces valuable synthesis gases with a particularly high CO content. As a result, it can be used directly in many synthesis processes without upstream hydrogen separation. It therefore competes with the so-called partial oxidation process, which also achieves a high CO content by reacting methane with oxygen. However, the pure oxygen that is required with this variant has to be produced with considerable energy costs. Moreover, the dry reforming process in particular provides relevant cost advantages relative to partial oxidation when used in small and medium-sized plants.

The conditions in the new reactor tube differ considerably from those for conventional technologies. For example, catalyst coking is a problem in dry reforming processes. Simulation calculations carried out by Karlsruhe KIT enable a deeper understanding of the complex reaction kinetics. These calculations can be used to better adapt the processes and components. Much depends on developing corresponding nickel and cobalt catalysts that meet industrial requirements. The project partners BASF, hte and Dechema are collaborating in the development of the catalysts.

If the pilot phase runs successfully, the project partners want to offer the dry reforming process on the market when the subsidised project comes to an end in 2017 and construct a reference plant with a customer.