Preparation Of Ni-B/KIT-6 Amorphous Catalyst And Its Catalytic α-pinene Hydrogenation

Turpentine was a kind of renewable resource;it was widely available,cheap and easy to synthesize many green products with high added value.Pinene（α-pinene andβ-pinene）was the main component of turpentine.This was attributed to the unsaturated double bond in the structure;the chemical properties of pinene were relatively active,which can be hydrogenated.α-pinene can be hydrogenated to produce cis-pinane and trans-pinane.Cis-pinane was widely used in perfumery,initiator,medicine and other industrial production due to its advantages of low steric hindrance and high reactivity.Therefore,choosing a catalyst with good performance to catalyze theα-pinene hydrogenation system had laid an important foundation for the further utilization of turpentine.In this manuscript,the self-made KIT-6（ordered three dimensional bicontinuous cubic Ia3d silica）was used as the catalyst carrier,supported Ni-B/KIT-6 amorphous catalyst was prepared by chemical reduction method.Furthermore,it was used for hydrogenation ofα-pinene.The following aspects were specifically studied:（1）KIT-6 was successfully prepared by hydrothermal method.The influences of concentration of hydrochloric acid,amount of cosolvent,amount of silicon source and hydrothermal temperature on the synthesis of molecular sieve were investigated by single factor.The optimal preparation conditions were determined as follows:initial molar ratio of TEOS:P123:HCl:H₂O:Bu OH was 1.0:0.017:1.83:195:1.33,hydrothermal temperature was 120℃.Subsequently,the synthesized KIT-6 was characterized by XRD,BET,SEM,TEM and TG-DSC.It was proved that the mesoporous silica KIT-6with three dimensional structures had been successfully synthesized.（2）Supported Ni-B/KIT-6 amorphous catalysts were prepared by chemical reduction method.By using a single factor experiment to combine orthogonal experiment,the best preparation conditions of this new catalyst are finally obtained:m(Ni²⁺)/m（KIT-6）was 1:4,the p H value of KBH₄ was 13,drip rate was 6 m L/min,B/Ni molar ratio was1.5,KBH₄ solution concentration was 0.5 mol/L.Thereafter,the prepared Ni-B/KIT-6amorphous catalyst was characterized,and the preparation conditions of the catalyst were correlated with the catalytic performance.Finally,the process conditions for hydrogenation ofα-pinene were optimized by single factor experiment and orthogonal experiment.The optimum reaction conditions were determined as follows:135℃,4.0MPa,5 wt%（α-pinene）,165 min.The conversion ofα-pinene reached 99.92%,and the enantioselectivity of cis-pinane reached 97.35%.After many experiments,it was determined that the catalyst had outstanding stability and can be used continuously for more than 6 times.（3）The catalysts before and after deactivation were characterized by XRD,BET,SEM,TEM-EDS,TEM-SAED and ICP.The catalyst deactivation may occur for the following reasons:（a）agglomeration of the catalyst after deactivation;（b）The carrier skeleton was partially destroyed,and the crystal shape of the catalyst changed from amorphous state to crystalline state;（c）Loss of active component Ni in the catalyst,as evidenced by ICP characterization.