Preparation And Development Research Of Hydrofining Catalyst On Ethylene Glycol

Ethylene glycol(EG)is a very important organic chemical material,it's manly used in production of polyester resin(fiber and film),and thus it is greatly needed by market.In recent years,problem such as EG's UV value doesn't satisfy the quality demand occurs in EG production units.It's due to trace amount of impurity taking place in the production that EG product cannot meet the index in the National standard(GB4649-2008)that premium grade EG's UV value should be more than 75%,92%,99%at the wave length of 220?275?350nm.In this case,EG quality is affected by impurity and cannot meet the demand of polyester resin production.Therefore,technology to enhance the EG's UV value and promote its affinity value is needed by market.In this paper,fixed-bed hydrogenation technology was adopted,and nickel based EG hydrofining catalyst with carrier was prepared to hydrotreat petroleum routes' EG product which had substandard UV value and so as to promote its UV value.Main research content and result are shown as below:(1)Nickel based A type hydrogenation catalyst with ?-Al2O3 as its carrier and nickel based AT type hydrogenation catalyst with Al2O3-TiO2 as its carrier were prepared by separate-step impregnation method,and were evaluated with industrial feed under the same condition.The result showed that:the prepared A type catalyst exerted high activity when used in hydrofing EG to promote its UV value.Under the condition like space velocity =15h-1,T=353K,H2 volume =2.24L/h,P =0.2MPa,catalyst mesh number= 20?30,A3 catalyst could promote the feed's UV value from 8.2%,90.7%,97.9%to 71.3%,94.7%,100%respectively at the wavelength of 220nm,275nm,350nm;While the prepared AT type catalyst brought about unexpected phenomenal that the feed's UV value decreased at the wavelength of 220nm,275nm after being hydrotreated.(2)Various kinds of characterization methods like N2 adoption and desorption,NH3-TPD,SEM,XPS,XRD,TEM were adopted to analyze two kinds of catalysts and their related carriers,and the reason why AT type catalyst's hydrogenation product's UV value decreased at 220nm,275nm was studied with the help of characterization result.Compared with A type catalyst AT type catalyst possessed smaller specific area and pore diameter,and was not favorable for product diffusion;the surface acid of AT type catalyst and their carriers was stronger,and easy to cause side reaction,like condensation reaction which produced side product with longer carbon chain;Ni atom's electron-deficient property was enhanced due to the influence from Ti,Ni with higher valence had higher absorbability toward C=O,and thus it was difficult for product to desorb from catalyst's surface,which in turn leaded to aldol condensation to produce side product;large amount of hydroxyl group might lead to side reaction like aldehyde condensation,aldol condensation,Etherification.(3)Nickel based MA type hydrogenation catalyst with ?-Al2O3 as its carrier and Mg as its promoter together with nickel based MAT type hydrogenation catalyst with Al2O3-TiO2 as its carrier and Mg as its promoter were prepared by separate-step impregnation method and were evaluated with industrial feed under different condition.The result showed that:the introduction of Mg was beneficial to boost both the two kinds of catalyst's activity.Under the condition Like space velocity =15h-1,T=368K,H2 volume=2.24L/h,P =0.2MPa,catalyst mesh number= 2030,MA-1 catalyst could promote the feed's UV value to 84.3%(220nm),99%(275 um),100%(350nm)respectively,up to premium grade's national standard.MAT catalyst's hydrogenation product's UV value was also obviously increased under the same condition;According to stability test,the prepared MA catalyst showed excellent stability which can fit the industrial need.(4)Various kinds of characterization method was utilized to study the Mg's Mechanism of additives when loaded on different carriers of two EG hydrofining catalysts.The addition of Mg addictive helped to reduce aggregation of Nikcel,and made nickel better distributed on catalysts' surface;Mg might react with Al2O3 to form MgAl26O40 phase like magnesium aluminate spinel,which inhabited the formation of NiAl2O4 which was hard to be reduced,leading more Nickel form NiO phase which was easy to be reduced,and thus enhanced the catalysts' reduction ability;The addition of Mg brought about the NiO grain refinement,so active component had better distribution;The surface acid of catalyst was decreased and then side reaction took place less.The Mg additive had active effect in promoting catalysts'activity.(5)The prepared AT type EG hydrofining catalyst was put into industrial application and application result showed that this catalyst was suitable to hydrotreat C9+ cut of pyrolysis gasoline,it had good activity and olefin saturation capacity under lower temperature,and high tolerance toward gums and great stability.