Adsorption Separation Of Acetylene And Ethylene With M-gallate Framework Materials

As technologies advancement,the standard for quality of basic chemical materials is pushed higher and higher.Ethylene of high purity is one of quite important chemicals for the worldwide chemical industries.The traditional technologies of separating ethylene and acetylene is energy-inefficient,so it is significant to explore adsorption separation technology that has been recognized as the most potential technology in the 21th century.To produce acetylene and ethylene friendly-environmentally,the dissertation reports a new serieal of metal organic frameworks(M-gallates)which can highly efficiently separate acetylene and ethylene for the first time.First,preparation of M-gallates(M=Mg,Co,Ni)framework materials were studied,and their stability was investigated.The results showed that the series of materials were quite stable in air,without changes of structures and acetylene uptakes.After soaking in the water and ethanol,the series of materials were moderately stable in structures,but still occurring a slight change in crystal structure.The longer the materials were settled in the water and ethanol,the higher ethylene uptakes of Co-gallate and Ni-gallate materials,however that of Mg-gallate materials was opposite.Then,Adsorption isotherms of acetylene and ethylene were collected in these three materials.On basiss of single-component isotherms,the IAST selectivity of C2H2/C2H4 was calculated and the adsorption heat of acetylene and ethylene was also checked by using Clausius-Clapeyron equation.The results revealed that the ethylene uptakes at 298 K and 1 bar in Mg-gallate,Co-gallate and Ni-gallate were 4.41 mmol/g,3.90 mmol/g,3.61 mmol/g respectively,ranking next to SIFSIX-1-Cu and NOTT-300 materials.At 298 K and 0.05 bar,outperforming ethylene uptakes of 3.21 mmol/g,3.11 mmol/g,2.62 mmol/g were observed on Mg-gallate,Co-gallate,and Ni-gallate,respectively.At 298 K and 1 bar,for adsorption of binary C2H2/C2H4(1/99),the IAST selectivity of Ni-gallate reached up to 48.41,higher than that of state-of-the-art SIFSIX-1-Cu(44.54),along with Mg-gallate of 22.46 and Co-gallate of 16.38.For binary C2H2/C2H4(50/50),the IAST selectivity was still higher than that of SIFSIX-1-Cu,reaching 56.7 along with Mg-gallate of 20.3 and Co-galalte of 13.7.The adsorption heat of Mg-gallate,Co-gallate and Ni-gallate materials ranged 25 kJ/mol?42 kJ/mol,38 kJ/mol?50 kJ/mol,39 kJ/mol?52.5 kJ/mol respectively.It was found the materials had strong interactions with acetylene,leading to high ethylene uptakes and high selectivity for C2H2/C2H4.At last,the dynamic adsorption separation performance was investigated in the fixed bed.The results showed that the materials were able to separate acetylene and ethylene effectively.After being regenerated and reused several times,the materials remained the uptakes of ethylene and acetylene as well as the selectivity of C2H2/C2H4,suggesting the series of materials were quite structurally and functionally stable.