Study On Adsorption Desulfurization Of Isoprene

Isoprene can be widely used in various industrial products and manufacturingprocesses, such as isoprene rubber, SIS thermoplastic elastomer, pharmaceuticalpesticide intermediates and a variety of fine chemical products. Isoprene is mainlyseparated from C5fraction which is the by-product in the pyrolysis of petroleumhydrocarbon for producing ethylene. C5fraction contains large amounts ofisoprene(about15-20%), we can obtain pure isoprene form C5fraction.But it isnecessary to make the sulfide concentration of isoprene to be less than5ppm to meetdownstream product applications.During the C5separation process, due to thepropinquity of boiling piont between isoprene and carbon disulfide make it is difficultto separate carbon disulfide from isoprene.The impurities of isoprene are carbondisulfide (mainly about95%of the total sulfur content),and a small number of alkylsulfide, mercaptans, etc.The total sulfur content is40-50ppm. The existence ofsulfides in isoprene seriously hindered the development and utilization of isopreneproducts.Therefore,in this paper, deep desulfurization of isoprene were studied.The adsorption desulfurization method will be used to research the properties ofdifferent adsorbents in this paper,the principle is to use the characterstics ofadsorption desulfurization adsorbent capable of selectively adsorbing sulfurcompounds in the isoprene, so that effection separation of sulfide and isoprene.Firstly,we take dynamic desulfurization experiments with different adsorbents. It was foundthat the adsorption desulfurization efficiency of HL-306、HL-307(provided by TianjinUniversity) and HL-301、HL-302(provided by Dalian institute of chemical physics) ishigh, and it has no interference on the isoprene raw materials. The four differentadsorbents were designed to be two groups of single-factor test for studying thesuitable reaction condition in the desulfurization of isoprene. And, adsorbent werecharacterized by fourier transform infrared spectrometer, X-Ray Diffraction, physicaladsorption instrument and scanning electron microscope forstudying structure-activity relationship between the structure and adsorption properties of adsorbent. Then, therecycle of adsorbent desulfurization performance were investigated. The adsorptionmechanism of adsorption isotherm and dynamic model was further explored throughthe static adsorption process.The result show that(1)HL-307is activated carbon and molecular sievecompound adsorbent, belonging physical adsorption;HL-301, HL-302,HL-306,isactivated carbon and zinc oxide compound adsorbent,belonging chemisoption;(2)HL-302adsorbent performance the best desulfurization properties,under the optimaloperating condition with the desulfurization rate of91.51%, sulfur capacity of1.97%.(3) After recycle of2times, desulfurization efficiency of HL-302was reducedto be59.55%.The HL-307desulfurization efficiency was reduced to be77.80%compare with89.25%of new adsorbent after reproduce6times.