2.1. Cu-MOFs (Cu3BTC2) and
ZIF-9(Co) preparation
In a typical synthesis process, 0.01 mmol Cu
(NO3)2.3H2O
and 0.03 mmol 1,3,5 pyromellitic acid were firstly weighed and dissolved
in 50 mL ethanol,then the mixture was stirred for 1 h and transferred to
an oven at 140 °C for 24 h. After being washed and dried,blue Cu-MOFs
powder was obtained. The synthesis of pure ZIF-9 was carried out in
aqueous solution at room temperature. 0.23 g benzimidazole and 0.28 g Co
(NO3)3.6H2O
were weighand dissolved in 40 ml of water.After the mixture was stirred
for 15 min, it was added 5 mL of ammonia and then stirred for 45 min.
Finally, it was kept in the dark for 8 h and dried by centrifuge to
obtain the product.
2.2 Composite sample preparation
In the process of synthesizing ZIF-9, a certain amount of
pre-synthesized Cu-MOFs was added during the aging process under dark
conditions. Cu-Co-x(x = 1, 2, 3, 4. x refers to the changed Cu-MOFs
mass) was obtained by adjusting the precursor of ZIF-9 synthesized by
benzimidazole and
Co(NO)3.6H2O.
Cu-Co-xP-2(x = 1, 2, 3, 4; x is the mass ratio of precursor to sodium
hypophosphite) composite catalyst was obtained by phosphating different
Cu-Co-2 (Cu-MOFs@ZIF-9) with a 0.125 g Cu-MOFs. Phosphating experiments
of the catalyst were carried out under the conditions of nitrogen
protection by calcination at 300 °C for 2 h. In addition, Cu-Co-x (x =
1, 2, 3, 4.) was subjected to phosphatization experiments of the same
degree (sodium hypophosphite has twice the mass of Cu-Co-x) to obtain
Cu-Co-2P-x (x = 1, 2, 3, 4.) composite catalyst. The phosphorylated
products of pure Cu-MOFs and ZIF-9 are referred to as Cu-P and Co-P. The
specific catalyst synthesis diagram is shown in Figure 1.