Study On Adsorption And Removal Of Carbon Disulfide In Isoprene By Modified Activated Alumina

Isoprene is a valuable resource that can be used in the petroleum cracking to ethylene industry,and can synthesize many important high value-added products,such as polyisoprene rubber,special rubber,petroleum resin,perfume,insecticide and other rubbers Products and fine chemical products,the development and utilization prospects are very broad.However,isoprene contains a small amount of sulfide mainly composed of carbon disulfide,and its presence will cause catalyst poisoning in the process of isoprene,seriously affecting the process of isoprene and product quality.Adsorption desulfurization technology has a simple process,low energy consumption,can meet the deep desulfurization requirements of isoprene without affecting the quality of raw materials,and has become a new type of deep desulfurization technology that has attracted much attention.The key of adsorption desulfurization technology is the preparation of adsorbent,so it has become an industrial demand to develop an adsorbent that can effectively remove carbon disulfide in isoprene.In this paper,pseudo-boehmite with different properties and pore-expanding agent are used as raw materials.A series of activated alumina carriers are prepared by the mixing and kneading method.A series of modified activated alumina adsorbents are prepared by the impregnation method.The sulfur content is 2000 ppm.Using isoprene as raw material,the effect of preparation conditions of modified activated alumina adsorbent on desulfurization performance of adsorbent was investigated by static adsorption method.The crystal structure,specific surface area,pore structure and surface functional groups of the adsorbent were characterized by XRD,mercury intrusion,CO₂-TPD,FT-IR and other characterization methods.The experimental results show that small pore small hole quasi-thin aluminite is selected as the raw material,the content of sesbania powder is1wt%,the carrier roasting temperature is 600℃,the roasting atmosphere is air,the active component K₂CO₃ loading is 18wt%,and the additive citric acid When the loading is1.8wt%,the prepared K₂CO₃/γ-Al₂O₃ adsorbent has the best performance for removing isoprene carbon disulfide,and the desulfurization rate in 3 hours is 63.0%.The characterization results show that the optimal K₂CO₃/γ-Al₂O₃ adsorbent has the characteristics of the largest pore volume of<10 nm and the largest number of weak base centers.Secondly,in the fixed adsorption bed reactor,using low sulfur isoprene as the raw material,the optimal K₂CO₃/γ-Al₂O₃ adsorbent dynamic adsorption process conditions were studied.The experimental results show that the raw material sulfur content is 50ppm,Under the optimized process conditions with a liquid hourly space velocity of 1 h-1 and an adsorption temperature of 10℃,K₂CO₃/γ-Al₂O₃ adsorbent has the best dynamic adsorption desulfurization performance,with an adsorbent breakthrough time of 158 h and a breakthrough sulfur capacity of 0.72%.Finally,using isoprene with a sulfur content of 2000 ppm as the raw material,the regeneration performance of K₂CO₃/γ-Al₂O₃ adsorbent was investigated by static adsorption method,and XRD characterization analysis of the adsorbent before and after regeneration was carried out.The experimental results show that the deactivated K₂CO₃/γ-Al₂O₃ adsorbent can recover partial desulfurization activity under the regeneration conditions of air flow rate 200 m L/min,regeneration temperature 600℃,regeneration time 4 h,and desulfurization in 3 h.The rate is 43.8%.Through characterization,it was found that the characteristic diffraction peak of K₂SO₄ was found in the XRD spectrum of the adsorbent after deactivation and regeneration,which was the main reason for the difficulty of recovering the level of fresh adsorbent for the activity of the regenerated adsorbent to remove carbon disulfide.