Temperature Swing Absorption
In the Temperature Swing Absorption process, HBr is regenerated to Br2 by oxidation with air over a proprietary GRT catalyst. The process is shown schematically in the following figure. Biogas or Natural gas containing methane (CH4) is brought into the process on the left. If the methane comes from biogas it will contain a substantial amount of CO2.
The feed gas is reacted with Br2 in the bromination reactor forming methyl bromide (CH3Br) and hydrogen bromide (HBr). Carbon dioxide (CO2), if present, simply passes through the process. Next the methyl bromide is passed over a proprietary catalyst to synthesize the desired products. Additional HBr is formed in this step. The next step involves absorption of HBr in an acid solution. HBr is readily absorbed but the products pass through. Warming the acid solution releases HBr into the gas phase, where it is mixed with air and oxidized over a catalyst to regenerate Br2. The regenerated bromine is then recycled back to the beginning of the process.
This process is based on proven technology and has lower technical risk than other process options. It is particularly attractive for a large scale installations using biogas as the feedstock.