10.1039/c5gc00379b
Nanoclusters of Cu(ii) supported on nanocrystalline W(vi) oxide: a potential catalyst for single-step conversion of cyclohexane to adipic acid
Hydrogen peroxide (50 wt% in water) was purchased from Merck KGaA, Darmstadt, Germany. Ammonium metatungstate, hydrate, anhydrous cupric chloride, cetyltrimethylammonium bromide (CTAB), hydrazine (80% aq. solution), ammonium hydroxide, cyclohexane (purity > 99.9%), acetonitrile (HPLC grade) were purchased from Sigma-Aldrich Co. All the chemicals were used without further purification. 
Cu(II) nanoclusters supported on nanocrystalline WO3 were prepared by modifying our own process, taking CuCl2 and (NH4)6H2W12O40*xH2O as precursors of Cu and W respectively.20 In a typical procedure 5.3 g (NH4)6H2W12O40*xH2O and 0.40 g of CuCl2 were dissolved in 16 g deionized water. Then the solution was made basic to a pH range of 8 using NH4OH solution dropwise. After that, a transparent and homogeneous precursor solution formed when 0.8 g CTAB was added into the solution. After the solution had been stirred for half an hour, aqueous hydrazine solution (0.4 g) was added to it. All the reagents were added maintaining the molar ratio: Cu:CTAB:H2O: The resulting precursor solution was transferred into a Teflon-lined autoclave with a stainless steel shell. The autoclave was sealed and maintained at 180 degC for 24 h. After cooling naturally to room temperature, the white products were collected after centrifugation, washed sequentially with distilled water and absolute ethanol to remove ions possibly remnant in the products, and dried in an oven at 100 degC overnight. Finally, the white powder underwent calcinations under an oxygen atmosphere at 550 degC for 6 h to yield canary-yellow products (catalyst).
Hydrogen peroxide
in water
50 wt%
wt%
hydrazine
aq. solution
80%
%
cyclohexane
purity
> 99.9%
%
(NH4)6H2W12O40*xH2O
dissolved
5.3 g
g
CuCl2
dissolved
0.40 g
g
deionized water
16 g
g
solution
pH range
8
CTAB
added
0.8 g
g
aqueous hydrazine solution
added
0.4 g
g
autoclave
maintained
180 degC
degC
autoclave
maintained
24 h
h
white products
dried
100 degC
degC
white powder
calcinations
550 degC
degC
white powder
calcinations
6 h
h