1. Field of the Invention
Embodiments of the invention relate to a facilitated transport membrane (FTM), which is operable for separating aromatics from a hydrocarbon stream having both aromatics and aliphatic compounds.
2. Description of the Related Art
Aromatic hydrocarbons (e.g., benzene, toluene, xylenes (BTX)) serve as important precursors in the production of petrochemicals. Additionally, the separation of aromatics is useful in upgrading and conditioning aromatic-containing streams in petroleum refineries. Therefore, it would be helpful to provide a useful and economical method to help recover aromatics from all these streams.
Typical methods for separating aromatics from petroleum refineries can include liquid/liquid extraction and extractive or azeotropic distillation. However, these methods are typically very costly and capital intensive, For example, distillation columns are typically up to 300 feet tall and can contain over 200 trays. The reflux ratios are generally greater than 10 and the process is therefore very energy-intensive. As such, more economical separation processes are needed.
Membrane pervaporation processes have been used to separate various types of hydrocarbons. However, many of these conventional membranes suffer from low selectivity (i.e., 5 to 20) and/or a low flux rate (0.03-0.3 kg/m2/h). Therefore, the commercial viability of conventional membranes is limited, preventing them from competing with conventional membrane pervaporation processes, such as extractive distillation. Therefore, it would be advantageous to have a FTM that has improved flux rates and/or selectivities over conventional membranes. It would also be advantageous if the FTM provided more strength and more stability than conventional membranes.