Effect of alkali metal cation modulated supported cobalt catalyst on reductive amination
Benzylamine,with its diverse applications in medicine,pesticides,dyes and spices,has garnered the attention for its industrial significance.While benzylamine can be synthesized through the reductive amination of benzaldehyde,the catalysts employed are often complex and expensive.In this work,we report a series of alkali metal cation-modulated cobalt catalysts supported on silica(Co-M/SiO2)prepared via a simple impregnation method.The catalysts were evaluated for the reductive amination of benzaldehyde.Notably,the best catalyst Co-Na/SiO2(Co2+∶Na+=1∶1.5),obtained the conversion of benzaldehyde to 100％and the selectivity of benzylamine to 94.6％.The doped catalyst increased benzylamine selectivity by 24.6 percentage points and decreased benzyl alcohol byproduct formation by 17.1 percentage points.Characterization of the catalysts(XRD,XPS,TEM,Raman,NH3-TPD,CO2-TPD,H2-TPD,TGA)provided insights into the structural and morphological properties of the catalysts.Results indicated that cobalt in the Co-Na/SiO2 catalyst primarily existed in the Co0 and CoOx form,and the addition of Na+changed the binding energy of Co0 species in the catalyst through electron transfer.Moreover,the Co-Na/SiO2 catalyst offered a balanced distribution of acid-base sites and optimal hydrogen adsorption capacities,favoring the reductive amination.The in situ DRIFTS experiments were utilized to illustrate the differences between species adsorption abilities and reaction processes over Co-Na/SiO2 and Co/SiO2 catalysts.Results revealed that the Co-Na/SiO2 catalyst had a superior ability to reduce benzaldehyde amines to benzylamine compared to the Co/SiO2 catalyst,as it could inhibit the formation of benzyl alcohol byproduct.This work provides a cost-effective and highly active cobalt-based catalyst preparation strategy for reductive amination,paving the way for future research in designing efficient catalysts for this important transformation.
benzaldehydebenzylaminereductive aminationalkali metal cation modulationCo-based catalyst
NETL
NSTL
万方数据
