Preparation And Catalytic Properties Of Carbon-based Copper Single-atom Catalysts

As single-atom catalysts have high atomic utilization and high catalytic activity,their application in the field of heterogeneous catalysis is increasing.In particular,carbon-based copper single-atom catalysts have the advantages of cheap and easily available raw materials and easy structure adjustment,which make them have broad application prospects in heterogeneous catalytic reactions.In order to develop carbon based-copper single-atom catalysts with high catalytic activity,a series of copper monatomic catalysts were prepared by using three different copper complexes as precursors and applied to the hydroboration of arylalkene and the ipso-hydroxylation of arylboronic acid.The specific research contents and results are as follows:（1）Preparation of Cu-N/C single-atom catalyst and its application in the hydroboration of arylalkene and the ipso-hydroxylation of arylboronic acid.Using copper-ethylenediaminetetraacetic acid complex（Cu-EDTA）as precursor and activated carbon as support,adsorption impregnation-calcination method was used to obtain0.2 wt%Cu-N/C（1:2）single-atom catalyst and 0.2 wt%Cu-N/C（1:2）single-atom catalyst with high stability and substrate universality.In the hydroboration of arylalkene,0.2 wt%Cu-N/C（1:2）exhibited high yield（76%）and reaction efficiency(1900 mmol_product/g _Cu),where the reaction efficiency was 14 times that of the 2 wt%Cu-N/C nanocatalyst.In addition,0.2wt%Cu-N/C（1:2）exhibits high stability and broad substrate applicability in arylalkene hydroboration reactions.0.2 wt%Cu-N/C（1:1）has the best reaction efficiency(3250mmol_product/g _Cu)in the ipso-hydroxylation of arylboronic acids,which is 6 times higher than that of 2 wt%Cu-N/C nanocatalysts.It was also found that the content ratio of Cu to N in the catalyst affected the catalytic activity of single-atom catalyst in different reaction systems.（2）Preparation of SCC-Cu-N/C single-atom catalyst and its application in the hydroboration of arylalkene.The SCC-0.2 wt%Cu-N/C-700 single-atom catalyst was obtained by the adsorption-impregnation-calcination method with sodium chlorophyll copper complex as the precursor and activated carbon as the support.The reaction efficiency(6800 mmol_product/g _Cu)of this catalyst in the hydroboration of arylalkene is 40 times higher than that of the same system of nanocatalysts.The catalyst still showed a high yield（64%）after cycling the reaction four times,and it showed broad substrate applicability in substrate expansion experiments.Through comparison,it is found that the reaction efficiency of SCC-Cu-N/C system catalyst prepared with sodium copper chlorophyllin is better than that of Cu-N/C system catalyst prepared with Cu EDTA,and the reaction efficiency of SCC-0.2 wt%Cu-N/C-700 single-atom catalyst is 3.6times that of 0.2 wt%Cu-N/C（1:2）single-atom catalyst.（3）Preparation of Cu-P/C single-atom catalyst and its application in the hydroboration of arylalkene.The 0.25 wt%Cu-P/C（1:1）single-atom catalyst was obtained by the adsorption-impregnation-calcination method with copper phytate（Cu-PA）complex as the precursor and activated carbon as the support.0.25 wt%Cu-P/C（1:1）was applied in the hydroboration of arylalkene,and the results showed that its catalytic reaction efficiency(1660 mmol_product/g _Cu)was much higher than that of 2.5 wt%Cu-P/C nanocatalyst(66 mmol_product/g _Cu).It is found that the catalytic activity of N-doped carbon-based copper single-atom catalyst is better than that of P-doped carbon-based copper single-atom catalyst.According to the cycle experiment and the substrate expansion experiment,it can be obtained that 0.25 wt%Cu-P/C（1:1）has high stability and substrate universality.