Abstract
Capturing CO2 emitted from industrial processes and power generation is important in the fight against climate change. Using polymer materials in capturing plants can reduce CO2 capture costs. This study focused on components used in columns for CO2 absorption and desorption (often referred to as "packing"). In the absorber column, the packing is a passive meeting place for the flue gas with CO2 and the solvent which absorbs the CO2.
Today, plants for solvent-based CO2 capture typically use stainless steel packings. Polymer-based materials and mass-produced components may reduce the investment costs for such plants. Using polymer-based materials may also reduce the degradation of the solvents, compared to using metallic materials.
The effect of solvent exposure was studied for a large number of materials in nine polymer families, using tensile properties as the assessment method. Three amine-based solvents were used, with CO2 loadings and exposure temperatures relevant for the absorber and desorber (70 °C and 125 °C). For exposure times up to 14 months, some materials with good chemical resistance were identified. For some polymer types, the molecular weight had an effect on the chemical resistance.
The packing in the absorber column must have a large effective surface area for CO2 absorption. Hence, the solvent should wet the packing material well, and enable solvent film forming on the packing surface. However, typical polymers are hydrophobic while the solvents are hydrophilic. In order to try to reduce the hydrophobicity of polypropylene (a low-cost polymer with good resistance to the solvents), various additives were tried, in different concentrations. Good results were obtained with an amine-functionalized polyhedral oligomeric silsesquioxane (POSS). Using 1 wt% of this POSS reduced the contact angle by about 20 %, and this effect remained after one year exposure in a solvent at 70 °C.
Today, plants for solvent-based CO2 capture typically use stainless steel packings. Polymer-based materials and mass-produced components may reduce the investment costs for such plants. Using polymer-based materials may also reduce the degradation of the solvents, compared to using metallic materials.
The effect of solvent exposure was studied for a large number of materials in nine polymer families, using tensile properties as the assessment method. Three amine-based solvents were used, with CO2 loadings and exposure temperatures relevant for the absorber and desorber (70 °C and 125 °C). For exposure times up to 14 months, some materials with good chemical resistance were identified. For some polymer types, the molecular weight had an effect on the chemical resistance.
The packing in the absorber column must have a large effective surface area for CO2 absorption. Hence, the solvent should wet the packing material well, and enable solvent film forming on the packing surface. However, typical polymers are hydrophobic while the solvents are hydrophilic. In order to try to reduce the hydrophobicity of polypropylene (a low-cost polymer with good resistance to the solvents), various additives were tried, in different concentrations. Good results were obtained with an amine-functionalized polyhedral oligomeric silsesquioxane (POSS). Using 1 wt% of this POSS reduced the contact angle by about 20 %, and this effect remained after one year exposure in a solvent at 70 °C.