| With the rapid development of human society,the demand for energy has also increased significantly.Although the research on solar energy,wind energy and tidal energy has developed rapidly,traditional fossil energy such as coal,oil and natural gas still occupies an important position.Natural gas,shale gas,coalbed methane and other gases mainly contain methane and other low carbon alkanes.As a new type of clean energy,compared with traditional fossil energy,natural gas,shale gas and coalbed methane have the advantages of low carbon and high efficiency,and are gradually replacing traditional fossil energy such as oil and coal.However,some gas fuels contain sulfides such as ethyl mercaptan(CH3CH2SH),carbonyl sulfide(COS),sulfur dioxide(SO2)and hydrogen sulfide(H2S),which have many adverse effects on equipment operation and pipeline maintenance,and affect the normal production of enterprises.Therefore,the high-precision removal of sulfides in gas fuels has become a research focus.In this paper,Nb2O5·nH2O nanosheets and Cu-Ti LDHs were prepared by hydrothermal method and microwave hydrothermal method,respectively.The phase structure,morphology and structural characteristics of the materials were characterized by X-ray powder diffraction(XRD),Fourier transform infrared spectroscopy(FT-IR),laser Raman spectroscopy(LRS),scanning electron microscopy(SEM),elemental energy spectrometer(EDS),specific surface area tester(BET),X-ray photoelectron spectroscopy(XPS)and 1H magic angle rotating solid nuclear magnetic resonance(1H MAS NMR).The desulfurization performance of the sample was studied by using 500 ppm methane containing ethyl mercaptan(CH3CH2SH/CH4)as a probe.The results show that niobic acid nanosheets have better desulfurization performance than amorphous niobic acid.Under the condition of space velocity 6000 h-1,the breakthrough adsorption capacity of amorphous niobic acid is 3.3 mg·g-1,while the breakthrough adsorption capacity of niobic acid nanosheets is 7.5 mg·g-1,and it still has good regeneration performance after five cycles.The adsorption of ethyl mercaptan on niobic acid nanosheets is mainly due to the weak adsorption of hydrogen bonds,and no other products are formed before and after adsorption,which is also the reason for the good regeneration performance of niobic acid nanosheets.The sample with Cu-Ti LDHs molar ratio of 3:1 has the best desulfurization performance,which is due to the larger interlayer spacing of 3:1 sample,which increases the specific surface area and exposes more active sites,resulting in the difference of desulfurization performance.Under the condition of space velocity of 12000 h-1,the breakthrough adsorption capacity is 147.8 mg·g-1.The removal of ethyl mercaptan on Cu-Ti LDHs is an adsorption/oxidation process.The strong basic hydroxyl groups and Cu2+on the surface of Cu-Ti LDHs oxidize ethyl mercaptan to diethyl disulfide and sulfonate,and the generated products are adsorbed on the surface of the adsorbent,resulting in the decrease of the regeneration performance of Cu-Ti LDHs.Cu-Ti LDHs were modified by controlling different calcination temperatures to prepare Cu-Ti bimetallic oxides(Cu-Ti LDOs),and the difference in desulfurization performance was studied.The results showed that the breakthrough adsorption capacity of Cu-Ti LDOs was much lower than that of Cu-Ti LDHs,which was due to the collapse of layered structure caused by high temperature calcination,the decrease of specific surface area,and the loss of hydroxyl at the main active site on the adsorbent surface,resulting in the decrease of desulfurization performance of the sample.Figure[25]table[7]reference[85]... |
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