Study On The Performance Of Co-based Encapsulated Catalysts For Hydroformylation Of 1-hexene

A large amount of α-olefins are produced by coal chemical industry and petrochemical industry.Hydroformylation of olefins,as one of the largest homogeneous catalytic industries in the world,is an important method to convert α-olefins into high value-added products.There are some problems in traditional catalysts for hydroformylation of olefins,such as serious loss of active components,difficult separation and recovery,high cost of Rh-based catalysts,expensive and toxic ligands,complex and tedious catalyst synthesis steps,long preparation cycle and so on.In this paper,starting with the encapsulated catalysts considering size effect,confinement effect and shape-selective effect,a heterogeneous catalyst with high activity and high n/i ratio of aldehyde was prepared using a simple and rapid preparation method.The catalyst was characterized by means of XRD,SEM,TEM,TPD,FT-IR,ICP-OES and XPS.The catalytic performance of the prepared encapsulated catalyst in hydroformylation of 1-hexene was evaluated.The optimum reaction conditions,cycle test and adaptability to different olefins were explored.1.Ni modified encapsulated Co@ZSM-5 catalysts with different contents Co and EDA were prepared by in-situ synthesis and H2 reduction and the effect of content of Co and EDA were investigated.When n(EDA):n(CoNi)=150 and the Co content is less than 3 wt%,the Co-Ni@ZSM-5 catalysts can be successfully prepared but gave low conversion of 1-hexene.The suitable EDA content can disperse Co and Ni well.When n(EDA):n(CoNi)=18,the sample with Co content of 5 wt%was prepared and the 1-hexene conversion and heptanal yield are 73.2%and 70.6%,respectively;when n(EDA):n(CoNi)=30,the ratio of n/I reached 2.5 although the conversion and yield were only 64.7%and 64.3%,respectively.2.Co-Ni@SiO2 encapsulated catalyst was prepared via in-situ synthesis and H2 reduction.The preparation method is simple and rapid.The content of Co and Ni will affect the formation of layer structure,and the best ratio of n(SiO2):n(Co):n(Ni)is 2:1:1.The confinement effect and shape-selective effect of layer structure are key to obtain high activity and high ratio of n-heptanal.Under the optimum reaction conditions of T=120℃,t=2 h,and P=5 MPa,the conversion of 1-hexene reached 99.6%,the selectivity of heptanal was 88.1%,and the ratio of n-heptanal to i-heptanal was 1.9.The activity was still high after recycled for 4 times.And the catalyst had good adaptability to C6-C12 α-olefin.That meant,it maintained the same activity more than 93%of conversion whatever to pure feed or mixed α-olefin.