Study On Adsorption And Separation Mechanism Of Niobium Based Nanotubes For Sulfide In Light Alkanes

The development and utilization of light alkanes is the mainstream trend of energy consumption in the future.Natural gas has many advantages:1.Environmental protection.The CO₂ emission generated during combustion is low,which can effectively reduce the greenhouse effect;2.Low-cost.Compared with coal,it has the same unit calorific value price;3.Safe and reliable.The characteristics of non-toxic and lighter than air make it difficult to gather and reach the critical explosion point,which makes it have good equipment friendliness in industrial production.With the increasing consumption of natural gas year by year,people pay attention to the acid natural gas wells with high development difficulty.However,more than 90%of the natural gas produced in such gas fields contain impurities such as hydrogen sulfide and organic sulfide,which can not be used directly.Because of its toxicity,flammability and corrosiveness,it will cause a series of environmental and safety problems.Therefore,how to remove sulfide in natural gas with high precision has become an important research content.In this paper,layered K₄Nb₆O₁₇ precursors were prepared by high temperature solid state method.After proton exchange,H₄Nb₆O₁₇ nanosheets（HNS）were obtained by liquid phase exfoliating method.Then protonated H₄Nb₆O₁₇ nanotubes（HNTs）were prepared by different methods by controlling the tube forming conditions.X-ray powder diffraction（XRD）,fourier transform infrared spectroscopy（FT-IR）,laser raman spectroscopy（LRS）,scanning electron microscopy（SEM）,transmission electron microscopy（TEM）,¹H magic-angle spinning nuclear magnetic resonance hydrogen spectroscopy（¹H MAS NMR）,X-ray photoelectron spectroscopy（XPS）and N₂-adsorption desorption were used to analyze the morphology,skeleton structure,the properties of surface hydroxyl functional groups and Br?nsted acid sites.The adsorption,desorption and cyclic regeneration of ethyl mercaptan（Et-SH）in simulated natural gas were investigated by using a fixed bed reactor gas chromatography combined device.Finally,the different adsorption properties of protonated nanotubes synthesized by different methods and conditions were evaluated.Through combined characterization,the relationship between nanotube morphology and surface hydroxyl Br?nsted acid site properties was expounded,and the reasons for the performance differences were analyzed.The H₄Nb₆O₁₇ nanotubes（HNTs）with large specific surface area and rich acid hydroxyl sites have been successfully prepared by curling H₄Nb₆O₁₇ nanosheets（HNS）.In the preparation process we controlled the contact mode and reaction temperature of the two phases of the HNS sol and acid.The experimental results show that the HNT-S are superior to the HNT-D.The adsorption capacity is about 73%higher than the latter at a space velocity of 5300 h^-1.After multiple cycles of regeneration,it can still maintain the desulfurization efficiency of more than 95%.Thus,it has a good regeneration performance.The HNT-Hx with high specific surface area,high tube formation ratio and high cruling degree prepared in the thermal field has higher desulfurization performance than that of HNT-OT at room temperature.Under the space velocity of 5300 h^-1,the HNT-Hx has a high adsorption breakthrough sulfur capacity of 63.6 mg·g^-1.This is attributed to the increase of the contact rate between the two phases of HNS sol and acid,the intensification of Brownian motion and the enhancement of proton transfer in the thermal field.However,due to the enhancement of the BA strength,the generation of more Lewis acid sites and the steric hindrance caused by irregular tubular structure,the difficulty of desorption and regeneration increases.Under the same regeneration conditions,the regeneration efficiency of HNT-H80 is about 90%.Figure[42]Table[8]Reference[116]...