Evaluation Of Cu-based And Co-based Catalyst For Deep Purification Of Carbon Monoxide In Polymerization Grade Olefins

The key for the developing of high-end polyolefin products is the purification technics of "polymerization grade" olefin.The dissatisfaction of purifying depth may lead the catalyst poisoning,even emergency shutdown of the entire plant.With the development of polyolefin technology,the quality requirement of the propylene is increasingly stringent,of which the concentration of CO is required to as low as 30 ppb(3 ×10-8,?).Catalytic oxidation method has industry potential which needs less equipment and higher removal efficiency,so development of key catalyst and technology for deep purification of carbon monoxide at low temperature is very important.In this dissertation,catalysts were prepared by co-precipitation method.The influences of active component(non-noble metal,e.g.Cu,Co)and additives(e.g.Zn,Ce,Pr,La)on the physico-chemical properties of catalysts and the catalytic performance in CO oxidation were characterized.The preparation method and formulation of CuxCoyZn0.15Ce0.15O?catalyst,the pre-treatment process and removal process were investigated systematically,by XRD,BET,H2-TPR,XPS techniques.The results and conclusions are obtained as followed:(1)The influences of the addition of non-noble metal active components(Cu,Co)and additives(Zn,Ce,Pr,La)on the physico-chemical properties of catalysts and the catalytic performance in CO oxidation were investigated.The addition of additives(Zn,Ce)could improve the dispersion of CuO and increase the specific surface area,finally promote the removal of trace amount of CO in olefin at low temperature.Compared with CuzZn0.15Ce0.15O? catalyst(T100 = 104 ?),CuxCoyZn0.15Ce0.15O? catalyst(T100=80?),which owes two active center(CuO,Co3O4),has higher activity of CO catalytic oxidation and better stability during the continuous reaction of 33 h.(2)The influences of the major factors,including precipitation,precipitation agent,calcination temperature,precipitation temperature,aging time,were also investigated systematically,in order to optimize preparation process of CuO-Co3O4-ZnO-CeO2 catalyst.The catalyst exhibited the excellent performance in the catalytic oxidation of CO,when it was prepared by co-current precipitation method,(NH4)2C03 as precipitating agent,precipitation at 80 0C,aging for 3h andcalcination around 400?.(3)The influence of the ratio of two active center(mcuO:mCo3O4= x:y)for the catalytic CO oxidation was studied,as the content of CuO(x)in CuxCoyZn0.15Ce0.15O? with 5%?65%(the sum of x and y is 70%).The results demonstrated that the CuxCoyZn0.15Ce0.15O?catalyst showed a better catalytic CO oxidation activity when the mass ratio of CuO and Co3O4(mCuO:mCo3O4)was 50:20.(4)The influences of pre-treatment process,reaction conditions and impurities on Cu0.5Co0.2Zn0.15Ce0.15O? catalyst for removal of CO from liquid propylene was studied.The results showed that Cu0.5Co0.22Zn0.15Ce0.15O? catalyst had a better catalytic CO oxidation activity at oxidation state than that at reducing state;water as an impurity had litter influence for CO catalytic oxidation activity.Under the conditions of 50 ?,LHSV = 8 h-1 and 3.0 MPa,it could remove the CO in liquid propylene from 10.0 × 10-6(?,volume fraction)to 2.0 × 10-8(?)with good stability during the continuous reaction of 66 h,which could meet the requirements of propylene polymerization and provided a broad prospect for industrial applications.