Study On The Removal Of Hydrogen Sulfide Using Functional Green Nonaqueous Solvent System

Hydrogen sulfide is a kind of toxic gas which widely exists in nature and human activities.It will cause serious corrosion to the pipeline in industrial production,which has greatly troubled the industrial operation and posed a great threat to human safety.Therefore,how to efficiently remove hydrogen sulfide has become a problem to be solved.In recent years,some achievements have been achieved by using non-aqueous solvents such as ionic liquids and eutectic solvents.In this paper,a series of functional non-aqueous solvents were developed to remove hydrogen sulfide.The desulfurizer was characterized by Fourier transform infrared spectroscopy（FT-IR）,scanning electron microscopy（SEM）,X-ray diffraction（XRD）,thermogravimetry differential thermal analysis（TGA-DSC）,X-ray photoelectron spectroscopy（XPS）and energy dispersive spectroscopy（EDS）.The research contents include the following five aspects:I)Four metal-based functional deep eutectic solvents were synthesized for the removal of hydrogen sulfide.Metal based deep eutectic solvents were prepared by mixing metal chlorides（zinc chloride,ferric chloride,chromium chloride and stannous chloride）and choline chloride in different proportions.The results show that the iron-based deep eutectic solvents（ferric chloride:choline chloride=4:1）was identified as the best desulfurizer.It was found that a relatively low temperature was in favor of the oxidation of H₂S.Moreover,the Fe-based deep eutectic solvents was proved to have good regeneration performance for at least 4 times.After characterization,the solid desulfurization product is sulfur with high purity and good crystal form,and could be recovered easily.II)Four kinds of deep eutectic solvents were synthesized and 5～30%polyethyleneimine was added to prepare basic functional eutectic solvents for dynamic absorption of hydrogen sulfide.The results show that the deep eutectic solvent with 25%polyethyleneimine content（ethylene glycol:choline chloride=2:1）has the highest desulfurization performance.It was found that a relatively low temperature（30^oC）was favorable for the absorption of H₂S.At the same time,we found that water plays an important role in the desulfurization system of functional eutectic solvent.Quantum chemical calculation proved that the absorption of hydrogen sulfide by functional deep eutectic solvents belongs to chemical absorption.The absorption/desorption cycle experiment indicated that the FDESs retain their good regeneration performance for at least five times.III)Iron/ethanolamine/deep eutectic solvent desulfurizer was prepared by using deep eutectic solvent as the solvent of iron/ethanolamine system.The iron/ethanolamine/deep eutectic solvent system showed a significantly enhanced desulfurization performance compared with DES solution of iron or alcohol amine separately.During the regeneration process,iron/ethanolamine/deep eutectic solvent desulfurizer showed a relatively high regeneration performance for at least three times.The solid desulfurization product is sulfur after characterization.IV)Hydrogen sulfide removal performances of four deep eutectic solvent based nanofluid systems was measured.It is found that copper nanofluid system of NF@Cu-1%has the best desulfurization performance and high regeneration performance.It is found that the ethanolamine,choline cation and sulfur were accumulated on the surface of Cu nanoparticles after absorption,and the regenerated surface elements were identified as copper and sulfur.Sulfur exists in the form of cuprous sulfide,and some sulfur was oxidized to zero-valent sulfur after regeneration.At the same time,the macroscopic kinetic behavior of the Cu nanofluid system was studied.It was found that the addition of nanoparticles can promote the mass transfer ability of the nanofluid system,thus enhancing the desulfurization ability.The increase of hydrogen sulfide concentration and temperature can enhance the mass transfer ability of the nanofluid system to a certain extent.V)Ethanolamine and ferric chloride were introduced into the ionic liquid to form an oxidizing functional ionic liquid solution,and the nanofluid composed of ethanolamine and ferric chloride and four kinds of inert nanoparticles was used to remove hydrogen sulfide.The silica nanofluid system of NF@Si O₂-0.5%was identified as the best desulfurization performance as well as regeneration performance.The regeneration rate of the optimal nanofluid system can exceed 88%,which is far higher than that before the addition of silica nanoparticles.It was found that the structure and morphology of silica nanoparticles remained basically unchanged in the absorption-regeneration process.The final desulfurization product was identified as sulfate.At the same time,the macroscopic kinetic behavior of the silica nanofluid system was also investigated.It was found that the addition of nanoparticles can promote the mass transfer ability of the nanofluid system,thus enhancing the desulfurization ability.Moreover,the mass transfer ability of the nanofluid system can be enhanced to a certain extent with the increase of hydrogen sulfide concentration and temperature.