CN102951669B - Method for preparing CeO2 nano solid spheres by microwave-assisted urea hydrolysis - Google Patents

Abstract

The invention relates to a method for preparing CeO2 nano solid spheres by microwave-assisted urea hydrolysis, which comprises the following steps of: dissolving Ce(NO3) 3.6H2O into deionized water to obtain Ce(NO3)3 solution; adding urea, PVP (polyvinyl pyrrolidone) and KBrO3 into the Ce(NO3)3 solution, and continuously and uniformly mixing to obtain mixed solution; moving the mixed solution into a reaction kettle, and placing the reaction kettle into a microwave hydrothermograph for reaction for 0.5-1.5h at the temperature of 160-190 DEG C; and centrifugal washing after reaction, and drying to obtain the CeO2 nano solid spheres. According to the invention, the Ce(NO3) 3-6H2O, the urea, the KBrO3 and the PVP are used as the raw materials, the microwave hydrothermal method and the urea hydrolysis principle are used for further synthesizing solid sphere-shaped CeO2 nano powder, and then, the CeO2 nano solid spheres of which the mean diameter is about 300nm can be obtained. The method disclosed by the invention has the specific advantages that the raw materials are relatively low in price, the process is simple in operation, and the microwave hydrothermal method which is pollution-free, clean and low-consumption is adopted for quickly preparing the CeO2 nano solid spheres under the condition of the urea hydrolysis.

Description

A kind of microwave-assisted hydrolysis of urea prepares CeO 2the method of nanometer solid sphere

Technical field

The present invention relates to one and prepare CeO ₂the method of nanometer solid sphere, particularly a kind of microwave-assisted hydrolysis of urea prepares CeO ₂the method of nanometer solid sphere.

Background technology

CeO ₂that there is fluorite type structure rare earth oxide.CeO ₂there is excellent electricity energy and optical property, have use widely at numerous areas such as photochemical catalysis, corrosion protection coating, gas sensor, fuel-cell electrolyte, polishing material, hydrogen-storing materials, be subject to people and pay close attention to widely.Catalysis aspect, nano Ce O ₂and matrix material has higher specific surface energy and oxygen storage capacity, show good catalytic performance: in the photocatalytic degradation of toluene, CeO ₂show and TiO ₂different degradation mechanism, CeO ₂it is CO that toluene can be made degradable ₂and H ₂o, and do not produce harmful intermediate product.In CO catalyzed oxidation, nano Ce O ₂and matrix material has good catalytic performance.CeO ₂stable performance, low price, toxicity is little, excellent property, is more and more subject to the extensive concern of investigators in recent years.

Up to now, people have used multiple method to prepare CeO ₂and composite material nanometer material.Qiu Kehui etc. for raw material, adopt sol-gel (sol-gel) legal system for V with cerous nitrate, citric acid and ammonium meta-vanadate ⁵⁺ion-doped nano CeO ₂powder [Qiu Kehui, Zhang Wei, Li Junfeng, Wang Kejia .V ⁵⁺the syntheses and properties [J] of ion-doped nano cerium oxide. China rare earth journal, 2009.4 (27,2): 209-212].But powder reuniting prepared by sol-gel method is comparatively serious, granularity is also comparatively large, have impact on its performance.Goldenrain tree precious equality is that cerium source is spherical by water heat transfer with cerous nitrate, fusiform and bouquet shape cerium dioxide [Luan Baoping, Yu Xibin, Liu Jie, Wang Litong, Hua Qingsong, Zhou Xiang, the CeO of different-shape ₂hydrothermal method preparation and characterization [J]. Shanghai Normal University's journal (natural science edition), 2011,40,2:157-162], but preparation powder granularity larger.The H such as Tang ₂o ₂make oxygenant, Ce (NO ₃) ₃do cerium source, go out the CeO along the growth of [100] crystal plane direction at 523K Hydrothermal Synthesis ₂monocrystal nanowire [Tang B, Zhuo L.H, Ge.J.C, eta1.Asurfactant-free route to single-crystalline CeO ₂nanowires [J] .Chem.Comm, 2005,3565-3567].Lin Yue etc. use reverse coprecipitation method to prepare CeO ₂and Dope nano-power [LinYue, Xiao-Ming Zhang.Structural characterization and photocatalytic behaviors ofdoped CeO ₂nanoparticles [J] .Journal of Alloy and Compounds, 2009,475,702-705].But low, the consuming time length of conventional hydrothermal method productive rate, energy consumption are high and greatly dangerous, are unfavorable for a large amount of production.In the pattern of vertical multiple types, spherical nano-powder has good physicochemical property because of its larger specific surface area, becomes the focus that investigators study.

Microwave attenuation materials method proposes at U.S. University of Pennsylvania R.Roy in 1992 novel method for synthesizing that utilizes the dielectric effect of microwave to water to heat, compared with traditional hydrothermal method, microwave attenuation materials method have rate of heating fast, be quick on the draw, the feature such as system is heated evenly, the homogeneous superfine powder of pattern can be prepared fast.

Summary of the invention

The object of the present invention is to provide a kind of cost low, simple to operate and be easy to control microwave-assisted hydrolysis of urea prepare CeO ₂the method of nanometer solid sphere.

For achieving the above object, the technical solution used in the present invention is:

Step one: by analytically pure Ce (NO ₃) ₃6H ₂o is dissolved in deionized water and obtains the Ce (NO that concentration is 0.01 ~ 0.2mol/L ₃) ₃solution;

By urea, PVP, KBrO ₃with Ce (NO ₃) ₃6H ₂o is (7 ~ 10): (3 ~ 5): (3 ~ 5): the mol ratio of 1 is by urea, PVP, KBrO ₃add Ce (NO ₃) ₃in solution, Keep agitation is even obtains mixing solutions;

Step 2: moved into by mixing solutions in reactor, be placed in microwave hydrothermal instrument in 160 ~ 190 DEG C of reaction 0.5 ~ 1.5h, centrifuge washing after reaction, obtains CeO after 80 DEG C of dryings ₂nanometer solid sphere.

Described Keep agitation is at 60 DEG C of Keep agitation 2h

The present invention is with Ce (NO ₃) ₃6H ₂o, urea, KBrO ₃, PVP(polyvinylpyrrolidone) be raw material, adopt microwave-hydrothermal method to utilize the CeO of the principle one-step synthesis solid spherical of hydrolysis of urea ₂nano-powder, obtains the CeO that mean diameter is about about 300nm ₂nanometer solid sphere.The distinctive advantage of this method is that raw material is relatively inexpensive, and technological operation is simple, adopts the microwave-hydrothermal method of pollution-free clean low power consuming can prepare CeO fast under the condition of hydrolysis of urea ₂nanometer solid sphere.

Beneficial effect of the present invention is embodied in: cost is low, simple to operate and be easy to control.In the present invention, microwave hydrothermal prepares CeO ₂the method of nanometer solid sphere can directly apply to doping and compound CeO ₂in the preparation of nano-powder, be CeO ₂base fabrication of new materials provide a kind of new way.In addition relative to conventional hydrothermal method, microwave-hydrothermal method has the advantage of environment protection energy-saving efficient.

Accompanying drawing explanation

Fig. 1 is CeO prepared by embodiment 1 ₂the XRD diffractogram of nanometer solid sphere;

Fig. 2 is CeO prepared by embodiment 1 ₂the stereoscan photograph of nanometer solid sphere;

Fig. 3 is CeO prepared by embodiment 1 ₂the transmission electron microscope photo of nanometer solid sphere.

Embodiment,

Embodiment 1:

Step one: by analytically pure Ce (NO ₃) ₃6H ₂o is dissolved in deionized water and obtains the Ce (NO that concentration is 0.01mol/L ₃) ₃solution;

By urea, PVP, KBrO ₃with Ce (NO ₃) ₃6H ₂o is that the mol ratio of 7:3:3:1 is by urea, PVP, KBrO ₃add Ce (NO ₃) ₃mixing solutions is obtained at 60 DEG C of Keep agitation 2h in solution;

Step 2: moved into by mixing solutions in reactor, be placed in microwave hydrothermal instrument in 180 DEG C of reaction 1h, centrifuge washing after reaction, obtains CeO after 80 DEG C of dryings ₂nanometer solid sphere.

By the CeO of the hollow ball-shape of gained ₂nano-powder is produced D/Max-2200pc type X-ray diffractometer with Japanese Rigaku company and is measured, and result as shown in Figure 1, obtains the CeO of the good pure phase hollow ball-shape of crystallinity ₂nano-powder, finds that the JCPDS card number of product is 33-0394, belongs to isometric system.The surface microscopic topographic of this sample adopts HITACHI S4800 type scanning electronic microscope to observe, and result is Fig. 2, and as can be seen from the figure that prepared is CeO ₂nanometer solid sphere, its mean diameter is approximately 300nm.The transmission pattern of this sample adopts JEOL JEM3010 type transmission electron microscope to observe, and result is Fig. 3.

Embodiment 2:

Step one: by analytically pure Ce (NO ₃) ₃6H ₂o is dissolved in deionized water and obtains the Ce (NO that concentration is 0.05mol/L ₃) ₃solution;

By urea, PVP, KBrO ₃with Ce (NO ₃) ₃6H ₂o is that the mol ratio of 8:3:5:1 is by urea, PVP, KBrO ₃add Ce (NO ₃) ₃mixing solutions is obtained at 60 DEG C of Keep agitation 2h in solution;

Step 2: moved into by mixing solutions in reactor, be placed in microwave hydrothermal instrument in 160 DEG C of reaction 1.5h, centrifuge washing after reaction, obtains CeO after 80 DEG C of dryings ₂nanometer solid sphere.

Embodiment 3:

Step one: by analytically pure Ce (NO ₃) ₃6H ₂o is dissolved in deionized water and obtains the Ce (NO that concentration is 0.1mol/L ₃) ₃solution;

By urea, PVP, KBrO ₃with Ce (NO ₃) ₃6H ₂o is that the mol ratio of 9:4:3:1 is by urea, PVP, KBrO ₃add Ce (NO ₃) ₃mixing solutions is obtained at 60 DEG C of Keep agitation 2h in solution;

Step 2: moved into by mixing solutions in reactor, be placed in microwave hydrothermal instrument in 170 DEG C of reaction 1h, centrifuge washing after reaction, obtains CeO after 80 DEG C of dryings ₂nanometer solid sphere.

Embodiment 4:

Step one: by analytically pure Ce (NO ₃) ₃6H ₂o is dissolved in deionized water and obtains the Ce (NO that concentration is 0.2mol/L ₃) ₃solution;

By urea, PVP, KBrO ₃with Ce (NO ₃) ₃6H ₂o is that the mol ratio of 10:5:4:1 is by urea, PVP, KBrO ₃add Ce (NO ₃) ₃mixing solutions is obtained at 60 DEG C of Keep agitation 2h in solution;

Step 2: moved into by mixing solutions in reactor, be placed in microwave hydrothermal instrument in 190 DEG C of reaction 0.5h, centrifuge washing after reaction, obtains CeO after 80 DEG C of dryings ₂nanometer solid sphere.

Claims (2)

1. a microwave-assisted hydrolysis of urea prepares CeO ₂the method of nanometer solid sphere, is characterized in that comprising the following steps:

Step one: by analytically pure Ce (NO ₃) ₃6H ₂o is dissolved in deionized water and obtains the Ce (NO that concentration is 0.01 ~ 0.2mol/L ₃) ₃solution;

By urea, PVP, KBrO ₃with Ce (NO ₃) ₃6H ₂o is (7 ~ 10): (3 ~ 5): (3 ~ 5): the mol ratio of 1 is by urea, PVP, KBrO ₃add Ce (NO ₃) ₃in solution, Keep agitation is even obtains mixing solutions;

Step 2: moved into by mixing solutions in reactor, be placed in microwave hydrothermal instrument in 160 ~ 190 DEG C of reaction 0.5 ~ 1.5h, centrifuge washing after reaction, obtains CeO after 80 DEG C of dryings ₂nanometer solid sphere.

2. microwave-assisted hydrolysis of urea according to claim 1 prepares CeO ₂the method of nanometer solid sphere, is characterized in that: described Keep agitation is at 60 DEG C of Keep agitation 2h.