Effect of Ultrasonic Pretreatment on the Formation of SAPO-34 for CO2 capture

Carbon dioxide is the sole contributor towards global warming. Therefore the growing atmospheric CO2 concentration and its impact on climate have motivated widespread research and development aimed at slowing or stemming anthropogenic carbon emissions. Additionally, in the natural gas processing industry, corrosive impurities known as ‘acid gases’, typically CO2 and hydrogen sulfide (H2S) are undesirable. Due to the extreme development of adsorption technology and the increase in adsorbent synthesis, it has been considered to be one of the most promising techniques for the capture of CO2 from natural gas. Zeolites are considered efficient in this particular application and due to the high surface area and porosity of SAPO-34; it is predominant for CO2 capture. In the present work, synthesis of SAPO-34 was successfully performed via hydrothermal synthesis for 24 h using TEAOH as structure directing agent (SDA). However, attempt to reduce the synthesis duration of SAPO-34 through ultrasonic pretreatment was not successful. The characterization studies were carried out by using scanning electron microscope (SEM), and X-ray diffraction (XRD). From XRD results, a relative crystallinity of 90% based on XRD peak intensity at 2θ = 9.5° and less intense peaks at 2θ = 21.5°, 22.6°, 23° & 35.9 was obtained for the sample synthesized under hydrothermal conditions for 24 h without ultrasonic pretreatment The SEM micrographs showed that SAPO-34 crystals having an average crystal size of 2 μm with homogeneous size distribution were obtained. Both XRD and SEM analysis confirmed the formation of SAPO-34 under hydrothermal synthesis for 24 h without ultrasonic pretreatment. Nevertheless, samples synthesized under ultrasonic pretreatment coupled with the reduction of synthesis durations ranging from 15 min to 3 h did not show SAPO-34 structure and morphology mainly due to the systematic errors. After the characterization, SAPO-34 particles were tested for its CO2 adsorption characteristics and the adsorption capacity was comparable with those results reported in the literature.