Construction Of Zinc-based Layered Double Hydroxides Nanosheets And Their Adsorption Properties For Ethyl Mercaptan

With the rapid development of social economy,environmental problems have attracted more and more attention.In order to reduce the negative impact of environmental problems,people pay more and more attention to the use of clean energy.As a typical representative of natural gas,its demand and consumption are increasing,and it is gradually occupying the dominant position of fossil energy.However,some sulfur compounds contained in natural gas will corrode the equipment,resulting in catalyst poisoning,which seriously affects the efficiency of chemical production and needs to be properly removed.In this paper,layered double hydroxides nanosheets（LDHs-NS）with Zn as divalent metal were successfully prepared by solvothermal method using ethylene glycol（EG）as reaction medium,including Zn Ti-LDHs-NS,Zn Al-LDHs-NS and Zn Al Ti-LDHs-NS.Powder X-ray diffraction（XRD）,Scanning electron microscopy（SEM）,Transmission electron microscopy（TEM）,High-resolution transmission electron microscopy（HRTEM）,Fourier transform infrared spectroscopy（FT-IR）,N₂ isothermal adsorption desorption and X-ray photoelectron spectroscopy（XPS）were used to characterize the phase structure,morphology,specific surface area,pore structure and element state of the samples.The desulfurization performance of the prepared samples for Et-SH was investigated by dynamic adsorption of ethyl mercaptan（Et-SH）from natural gas in a fixed bed reactor.The adsorption process was simulated by density functional theory（DFT）,and the main adsorption sites and adsorption effects were discussed at the molecular level.The results show that the specific surface area and desulfurization performance of the nanosheets prepared by solvothermal method are significantly improved compared with the layered materials.The different washing solvents in the preparation process also have a significant effect on the phase structure and desulfurization performance of the samples.For Zn Ti-LDHs-NS,the highest breakthrough adsorption capacity of Et-SH reached 26.63 mg·g^-1,which was about 3 times that of Zn Ti-LDHs prepared by hydrothermal method.The samples obtained by different washing solvents are all nanosheets.The addition of anhydrous ethanol during the washing process can increase the porosity of the sample,make the sample fluffier,and have a larger specific surface area.Adding deionized water can more effectively remove residual organic solvents.After using Al atoms to replace Ti atoms,the sample obtained by washing with anhydrous ethanol was nanosheets.The breakthrough adsorption capacity for Et-SH was 32.52mg·g^–1.After adding deionized water,the sample recovered the layered structure and the breakthrough adsorption capacity was greatly reduced.DFT calculation results show that the H atom in the hydroxyl group on the surface of Zn Ti-LDHs-NS and Zn Al-LDHs-NS is the main adsorption active site,and the S···H bond interaction is mainly formed when the adsorption occurs.PDOS analysis results show that the hybridization of S 3p orbital and H 1s orbital promotes the formation of S···H bond.At the same time,the adsorption mode of EG residue on the nanosheets was simulated,and it was found that EG retention on Zn Ti-LDHs-NS hindered the adsorption.After the Al atom replaces the Ti atom,the average bond length of the Al-O bond is smaller than the average bond length of the Ti-O bond,resulting in a more compact distribution of hydroxyl groups on the surface of the nanosheets,and more ways of charge transfer between Et-SH and nanosheets.The adsorption energy is larger,which has a certain effect on the adsorption of Et-SH.When Al atoms replace part of Ti atoms,the phase structure of Zn Al Ti-LDHs-NS is similar to that of Zn Al-LDHs-NS.The breakthrough adsorption capacity of the samples prepared by the same washing solvent for Et-SH is between that of Zn Ti-LDHs-NS and Zn Al-LDHs-NS.Figure[37]Table[7]Reference[120]...