| Compared with coal and oil,small molecular alkane gas has the advantages of less pollution and high-energy utilization,so it has been vigorously developed.However,the widespread sulfide has the disadvantages of corroding pipelines,polluting the environment and poisoning catalysts,which seriously hinders the development of this kind of energy.Therefore,the removal of sulfide from small molecular alkane gas has become an urgent problem to be solved.On the other hand,pure sulfide is also an important chemical raw material.Therefore,it is of great environmental and economic benefits to realize the adsorption and separation between sulfide and small molecular alkane gas.Layered KNb3O8 and KTiNbO5 were prepared by high temperature solid-state method.HNb3O8 nanosheets(HNb3O8-NS)and HTiNbO5 nanosheets(HTiNbO5-NS)with fully exposed surface active sites were obtained by H+ion exchange and pillared stripping.X-ray powder diffraction(XRD),scanning electron microscopy(SEM),transmission electron microscopy(TEM),high resolution transmission electron microscopy(HRTEM),atomic force microscopy(AFM),laser Raman spectroscopy(LRS),N2-adsorption desorption,1H magic-angle spinning nuclear magnetic resonance(1H MAS MNR)and other modern characterization methods were used to characterize the phase structure,micro morphology,skeleton structure,channel structureand acid characteristics of the materials.A fixed bed reactor evaluated the adsorption and regeneration properties of the material,and the properties of ethyl mercaptan(Et-SH)desorbed from the material surface were determined.The adsorption simulation process was calculated by density functional theory(DFT)to reveal the molecular level adsorption mechanism of Et-SH adsorbed on two kinds of nanosheets.Finally,the difference of adsorption properties between the two nanosheets was evaluated,and the reasons for the difference were explained combined with the results of experiment and DFT calculation.The results showed that after stripping and recombination of layered H3ONb3O8 and HTiNbO5,loose nanosheets with fully exposed surface active sites were successfully obtained.In the system of HNb3O8-NS adsorbing Et-SH,the breakthrough adsorption capacity(Cap(BT))of stripped HNb3O8-NS is 51.5 times than layered H3ONb3O8.The regeneration desulfurization rate of HNb3O8-NS can still reach more than 94%after 9 cycles of regeneration.The test results of regeneration gas outlet show that Et-SH could be physically desorbed from the surface of HNb3O8-NS.Therefore,HNb3O8NS can realize the cyclic adsorption and separation of Et-SH in methane gas.DFT calculation shows that Et-SH has the strongest adsorption strength at the bridging hydroxyl site of HNb3O8-NS.Moreover,HTiNbO5-NS was constructed by replacing some Nb elements with Ti elements.In the Et-SH system adsorbed by HTiNbO5-NS,the electron cloud density distribution of the adsorption model shows that there is an obvious electron cloud overlap between the hydroxyl H atoms on the surface of HTiNbOs-NS and the S atoms of Et-SH,which directly proves the existence of S…H hydrogen bond.In addation,Mulliken charge population distribution results show that the S…H hydrogen bond may be formed by the intersection of the H 2s orbital of H atoms of HTiNbO5-NS hydroxyl and the S 3s and S 3p orbitals of S atoms of Et-SH.Finally,the effects of Ti substitution on the lamellar structure,hydroxyl content,hydroxyl acidity,specific surface area,pore volume,adsorption strength and adsorption properties of nanosheets were studied.The results of this study broaden the application connotation of hydrogen bond interaction and provide a new idea for the design of efficient Et-SH adsorbent.Figure 37 Table 9 Reference 100... |
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