Partially calcined gismondine type silicoaluminophosphate SAPO-43: Isopropylamine elimination and separation of carbon dioxide, hydrogen sulfide, and water

Selective removal of carbon dioxide and hydrogen sulfide from other gases is usually difficult to achieve because most of the available sorbents will also adsorb other unwanted molecules. SAPO-43 is a microporous sorbent with appropriate dimensions and characteristics for these types of separations, but previous studies have shown that, because of low thermal stability, it is not suitable. This study discusses a procedure developed to partially remove the organic moiety used for synthesis of SAPO-43 while preserving the framework. The thermal process to remove the template (isopropylamine) results in decomposition of the species, which is believed to be a result of a Hofmann elimination process. Afterward, the partially calcined silicoaluminophosphate can be used as a selective adsorbent to separate molecules like CO₂, H₂O, and H₂S while excluding molecules such as N₂, CH₄, and O₂. In general, it was found that SAPO-43 has adsorption capacities of 1.1, 4.93, and 2.52 mmol/g for CO₂, H₂O, and H₂S, respectively, at 25 °C and atmospheric conditions.