Synthesis Of SSZ-13 Zeolite And Research On Adsorption And Separation Of CH₄/CO₂

Adsorption is one of the common industrial methods for removing carbon dioxide from natural gas.Due to its simple equipment,mild operating conditions and low energy consumption,it is widely concerned.In this paper,firstly,we introduce the commonly used adsorbents for adsorption of carbon dioxide,including carbon-based molecular sieve,silica gel,MOF and zeolite molecular sieve.Zeolite molecular sieves have good thermal stability,large surface area and are easy for ion exchanging.In many molecular sieves,molecular sieve pores containing a large number of uniform pore diameter.In recent years,because of this unique advantage,zeolite molecular sieves have been widely used in gas adsorption separation,industrial catalysis and other fields.In this study,CHA molecular sieves were synthesized by the turning crystal method using Na Y zeolite.SSZ-13 zeolite was synthesized with benzyl trimethyl ammonium hydroxide.Effects of seed,crystallization method,crystallization temperature and crystallization time on synthesis of SSZ-13 were explored.This paper focuses on the differences in the performance of carbon dioxide in the adsorption of methane by K-SSZ-13,Na-SSZ-13,3A,4A and 5A molecular sieves.The adsorption time and adsorption capacity of the mixed gas were indicated by gas chromatograph.K-SSZ-13 molecular sieve was found to have the highest adsorption and selectivity of carbon dioxide in these molecular sieves,respectively 3.3mmol/g and 116.85.The reason of the high adsorption selectivity is the “trapdoor” mechanism of the K-SSZ-13 zeolite.The actually separation was based on the ability of the CO2 molecule to induce temporary reversible K+ cation deviation from the center of pore apertures.However,the LTA zeolite did not demonstrate this mechanism.Methane and carbon dioxide gases are separated only by the "screening effect" of molecular sieves.At the same time,in this paper,the desorption experiment of these molecular sieves was carried out,and there were two desorption peaks in the SSZ-13 molecular sieve,while the LTA molecular sieves had only one desorption peak.Moreover,the desorption temperature of K-SSZ-13 molecular sieve was lower than that of Na-SSZ-13 molecular sieve,indicating that the K-SSZ-13 molecular sieve was easy to be regenerated.K-SSZ-13 molecular sieve is a good adsorbent for carbon dioxide adsorption.