Studies On The Separation Of Long-chain Olefin/Paraffin From F-T Synthetic Oil Mixture

Long-chain ?-olefins are a kind of raw material,which are used to produce surfactant,oil field chemicals,olefin copolymer,plasticizing alcohol and lubricating oil.Fischer-Tropsch synthetic oil mixture has abundant long-chain ?-olefins.Obtaining highly purified long-chain ?-olefins from F-T oil not only improves the added value of long-chain?-olefins but also economic efficiency of F-T synthetic oil.Studies on the separation of F-T synthetic oil mixture are a demanding task.The methods of freezing,distillation,extraction and adsorption wered employed to separate the mixtures.Combining distillation and?-complexation adsorption method was determined as the final solution to separate long-chain ?-olefin/paraffin.The means of packed tower vacuum batch distillation was used to fractionate the F-T synthetic oil preliminarily.Different vacuum degrees and reflux ratios on the impact of fractional compositions were discussed;the temperature sections of single carbon mixtures were confirmed.A magnetic complex separation adsorbent—AgNO₃/MCM-41/NiFe₂O₄ was designed and synthesized via the incipient wetness impregnation.The samples were characterized and analyzed by scanning electron microscope?SEM?,transmission electron microscope?TEM?,powder X-ray diffraction analysis?XRD?,nitrogen adsorption-desorption analyses,Fourier transform infrared spectroscopy?FT-IR?,vibrating sample magnetometer?VSM?and etc.The tests showed that the obtained products were composed of NiFe₂O₄ with spinel structure and MCM-41 with hexagonal arrangement of unidimensional mesopores.When the loading amount of AgNO₃ was 0.2g/g magnetic carrier,AgNO₃ was finely dispersed in the channel.The specific surface area and most probable pore size were717.89m2/g,2.94 nm.For the C₁₁ ?-olefin/C₁₁ paraffin mixtures,adsorption behaviours of C₁₁ ?-olefin on magnetic adsorbent were investigated.Results showed that adsorbents have preferential adsorption for long-chain olefins.The one-stage equilibrium adsorption capacity and adsorption time were 2.14g/g,100 min respectively.The adsorption temperature and initialolefin concentration were studied.The optimal adsorption temperature was 20?.When the mass percent of olefin was up to 60%,the adsorption capacity reached saturation.In the200?,0.08 Mpa conditions,the adsorbent could be completely regenerated after 3h by vacuum heating.Adsorptive selectivity,adsorption and magnetic recovery of adsorbents after reuse ten times were investigated.The recovery was up to 98.9% and the selectivity and adsorption of olefin decreased slightly?1.93g/g?.But the changes still can satisfied requirements for olefin adsorbed selectively.