1.. Impregnation method
A certain amount of zrocl2.8h20 was dissolved in an appropriate amount of deionized water, and ammonia was added to form a hydrogel. The pH value was adjusted to 9.0. After being placed at room temperature for 12h, the precipitate was filtered and washed with deionized water to be chlorine-free (0.1 mol·L ~ AgN03 solution was used for detection). Then the filter cake was soaked in anhydrous ethanol and alcoholized for 12 h in a constant temperature drying oven. After cooling to room temperature, remove and filter the remaining anhydrous ethanol. After drying for 383 K, the white powdery zirconium hydroxide carrier was obtained. The prepared Zr(OH)4 precursor was impregnated to prepare the catalyst in the following three ways :(1) A small amount of calculated concentration of ammonium metatungstate aqueous solution was prepared to moisten the zirconium hydroxide powder and stir it to mix it fully. After drying, the prepared catalyst was calcined at different temperatures. (2) the zirconia hydroxide powder was immersed into an aqueous solution of ammonium tungstate at a certain calculated concentration, evaporated, dried and roasted at different temperatures. The catalyst was denoted as WZH(B) :(3) the process was the same as that of (2). The aqueous solution of ammonium tungstate was changed to ammonium tungstate aqueous solution, and the catalyst was denoted as WZH(C).
2. Coprecipitation method
Weigh ZrOCl2·8H20 and H2WO4 as reserve by molar ratio 1:2. The experimental process was as follows: the solution was prepared with a pH adjusted value and a total of precipitates; the solution was mixed with stirring; the solution was washed and dehydrated; the solution was prepared with precursors; and the solution was synthesized by heating.
A. H2WO4 is yellow powder, insoluble in water, sulfuric acid, nitric acid and hydrochloric acid, but soluble in HF acid, alkali and ammonia. In the experiment, H2WO4 was added to a certain amount of concentrated ammonia water and stirred thoroughly for 24h before being completely dissolved.
B. ZrOCl2·8H20 was dissolved in deionized water and made into 0.5 mol·L_1 solution. Impurities were filtered. ZrOCl2·8H20 solution was added to the ammonia solution of H2W04 according to the stoichiometric ratio. Electromagnetic stirring was used in the whole process. The precipitate was dehydrated by centrifugation and washed with anhydrous ethanol for five times.
The precipitate was dried and calcined at 600℃ for 2h.
C. Place the precursor powder in a muffle furnace. 1# and 2# samples were obtained by holding them for 0.5 h and 1h at 1200℃ and quenching them in air to room temperature.
3. The hydrothermal method
ZrO(N03)2•5H2O and N5H37W6O24•H2O were used as raw materials. 50ml of 0.2mol/L Zr solution and 50ml of 0.4mol/L W solution were configured, and the mixture was continuously stirred for 2.5h. Then add 35ml, 6mol/L of HCl and stir it for 3 hours, then heat it at 180℃ for 15 hours. Filter, wash with deionized water, and dry at 60℃. The resulting precursor was heated at 500℃ for 6h to obtain ZrW2O8 powder.
The ZrO2, WO3 (5 mol%) — ZrO2 andWO3 (10 mol%) — ZrO2 were prepared. The synthesis method is solution combustion synthesis and solution calcination synthesis. ZrO(NO3)2·xH2O) and hydrated ammonium meta-tungstate were used as the precursor and urea as the fuel.
A certain amount of zirconium nitrate, ammonium mettungstate and urea was dissolved in the smallest amount of water and preheated at 400 ℃ in a muff furnace. Mixture will suddenly burn (ignited), generated a foam material WO3 – ZrO2
ZrO(N03)2 ‘5H20 and N5H37W6024’ H20 were used as raw materials. The Zr source solution of 50ml0.2mol/L and W source solution of 50ml and 0.4mol/L were configured. Mix the two ingredients in a molar ratio of 1:2, stirring continuously for 2.5 hours. Add 35ml of 6mol/ l of HCL and stir for 3 hours. Then it was transferred to teflon-lined Parr bomb where it was heated at 180 ° c for 15h, washed and dried at 60 ° c. 570 ℃ heating 6 h
2.1. Preparation of the Catalysts. The Two company’s supports were prepared from zirconium oxyhydroxide. Zirconium oxyhydroxide was obtained after precipitation of zirconium propylate (Zr (OPr) 4 70 wt % In propanol. Aldrich) in water while stirring (molar thewire water/propylate) 105). After 1 h of stirring,
The powder was filtered and thoroughly washed with water and dried at 393 K. Part of this powder was informs the as to the as an amorphous support; The remaining part was calcined in air at 773 K for 5 h, leading to a second type of support, i.e. for the crystallized zirconia.
Adopts coprecipitation preparation of WO3 – ZrO2 solid acid. To a certain concentration of ammonium tungstate solution with the mixture of ammonia water solution under strong stirring slowly drops to the oxygen zirconium chloride aqueous solution, the addition of ammonia to make the final solution of the 56 a value of 10 right, the sediment after high-speed emulsification 5 min, washing to remove chloride ion, filtering, drying, high temperature roasting 3 h: after get WO3 – ZrO2 solid acid
First, the ratio of tungsten, cerium and zirconium to n(W) : n(Zr)= 2:1, so that
(C, I) :((Ce)+ (Zr)) 1 0.5, 0.3, 0.1, product Ceo 5zro.5 1
O. CZ5, CZ3, CZ1. The preparation of CZ5 is as follows: weigh at 60℃
4.37g template CTAB was dissolved in lOOmL distilled water, denoted as solution 1; then
Zr(NO3)4·5H2O 5.1518 g was dissolved in 20mL water, Ce(N03). ,
6HzO 5.2107 g was dissolved in 30mL water, and then the two solutions were mixed evenly and set aside.
Let’s call it solution 2; When solution 1 has cooled to room temperature, add the solution with vigorous stirring
2. Keep stirring 30rain; Then add a drop of concentrated ammonia so that the pH: 9.7 appears
Tan sticky sol, continue to stir 2h; Transfer with teflon lining
Hydrothermal reactor, heat treatment in lo0~C water for 3 days; Remove and cool naturally to room temperature
After centrifugation, wash with distilled water to neutral, filter at i00. C. Dry overnight; The last
Calcined in a muffle furnace at a low temperature of 150 ~ C under steady air flow for 3h, then
It was roasted at 550℃ for 6h(1℃ / min). CZ3 and CZ1 were obtained by the same method. solid
Set (C1) : ((C)+(Zr)) 1 0.3, so that (Ce4) : (Zr4) :
3:1. The preparation method is the same as above, and the product is Ceo 7 Zro. 02.
SBA15 is first dissolved in a zirconium source (acetylacetone zirconium), followed by constant agitation. Then pour the ammonium tungstate solution into the mixture and stir for 1h. The solvent is then evaporated by a rotary evaporator. Precipitation 110℃ dry for 24h. Calcination at 800℃ for 3h.
Add 5 mol/ L of ammonia to 015 mol/ L of zirconium nitrate solution
To pH = 9 ~ 10, zirconia hydroxide was deposited at 100
The mother liquor at ℃ was aged for 24 h and then washed with deionized water to the pH of the filtrate
= 7, filtered and dried at 100 ℃, then immersed the zirconia hydroxide into the meter
In aqueous solution of ammonium metatungstate, the mixture was placed in an oil bath at 120 ℃
After reflux for 20 h, the product was finally dried at 110 ℃ and roasted at 800 ℃ for 3 h
WO3/ ZrO2 solid acid catalyst was prepared.
Preparation of wo, / sBA – 15 catalyst: H: wo. and
H2c: ‘O. Is the tungsten source, will be 0.05 g of H2w0. And 0.36 grams
H2c: O. Pour into a beaker with 60 mL distilled water at 90 ° c
Reaction until the solution becomes transparent, then add 0.45 g mesoporous
SBA 1 15 molecular sieve, when the solution is quickly evaporated, take the milk in the beaker
The liquid is dried at 100℃ overnight and calcined at 550℃ for 2 h
W03 / SBA 1 15(A) catalyst. At 0.05g H2W04