LOW-TEMPERATURE TECHNOLOGIES FOR CARBON DIOXIDE REMOVAL

The need for a profitable exploitation of low-quality natural gas reserves, characterized by a high content of acid gases (mainly CO2 and H2S), has recently boosted an intense research aimed at developing novel technologies for acid gas removal from natural gas. They represent an alternative to conventional technologies used for the same purpose, which are mainly based on chemical absorption into solvents and become energy-intensive at high acid gas contents due to the heat required for solvent regeneration. Novel technologies have been also developed for the upgrading of biogas, a renewable energy source which is produced from different feedstock materials and typically contains 35 - 50 vol% carbon dioxide. GASP (Group on Advanced Separation Processes & GAS Processing), led by Prof. Laura A. Pellegrini, has contributed to the research about novel low-temperature technologies for the separation of acid gases from natural gas/biogas by studying a process based on dual pressure low-temperature distillation. This work, which is dedicated to Prof. Laura A. Pellegrini on the occasion of her 65th birthday, presents a review of the research activity carried out in this field and compares the performances of two low-temperature distillation processes applied to CO2 removal from natural gas for the production of liquefied natural gas.