CN102153055A

CN102153055A - Solvent heat preparation method for batch graphite type carbon nitride

Info

Publication number: CN102153055A
Application number: CN2010105690503A
Authority: CN
Inventors: 刘建军; 钟恺凯; 左胜利; 于迎春
Original assignee: Beijing University of Chemical Technology
Current assignee: Beijing University of Chemical Technology
Priority date: 2010-12-02
Filing date: 2010-12-02
Publication date: 2011-08-17

Abstract

The invention discloses a solvent heat preparation method for batch graphite type carbon nitride, and belongs to the field of chemical new materials. The chemical composition of the carbon nitride is CxNyHz, wherein x, y and z are the atom number of elements in the molecular formula, x is equal to 2.8 to 3.2, y is equal to 4 to 5, and z is equal to 1 to 5. The method comprises the following steps of: weighing a plurality of raw materials in approximately stoichiometric ratio, taking a solvent in a volume which is 60 to 70 percent of the volume of a reaction kettle, raising the temperature to a set temperature (180 to 230 DEG C) at a certain temperature raising rate (5 to 20 DEG C per minute), and controlling the stirring speed (100 to 300rpm) of the reaction kettle; when the required temperature is reached, performing thermostatic reaction for 10 to 20 hours; and then performing natural cooling to room temperature, washing the sample for several times by using water and acetone, and drying the sample to obtain yellow powder, namely a target product. The preparation method has simple operation, mild condition and low cost; and the prepared graphite type carbon nitride has good crystallization, high purity and high yield, and is suitable to be used as a precursor for experiment synthesis and performance research for further preparing a macro high-density carbon nitride phase.

Description

The solvothermal preparation method of batch graphite mould carbonitride

Technical field

The present invention relates to a kind of preparation method of batch graphite mould carbonitride and be further used for the high pressure phase synthetic use, belong to the new chemical materials field as precursor.

Technical background

In 1989, Liu and Cohen predicted solid carbon nitrogen covalent compound β-C theoretically ₃N ₄The phantom amount and the highest diamond of known hardness quite or better.There is low-density graphite mould carbonitride (g-C in researchist's prediction subsequently ₃N ₄), with four kinds of highdensity other carbonitrides (α-C mutually ₃N ₄, β-C ₃N ₄, cube-C ₃N ₄, false cube-C ₃N ₄).In the carbonitride structure of theory prediction, the compact-type carbonitride is (as α-C ₃N ₄, β-C ₃N ₄, pc-C ₃N ₄, c-C ₃N ₄) hardness that can match in excellence or beauty with diamond is arranged, become novel superhard material thereby be expected to substitute diamond.But because the thermodynamic stability height of carbon atom and nitrogen molecule, so directly synthetic compact-type carbonitride is also very difficult, and graphite mould carbonitride (g-C ₃N ₄) synthetic mainly obtain by high temperature pyrolysis or solvent thermal reaction by carboritride and different nitrogen sources; synthesis technique is than simple and easy; and the graphite mould carbonitride can be used as the precursor of synthetic compact-type carbonitride; also can be used as mesoporous material and abrasion resistance material; especially in recent years with the graphite mould carbonitride as novel non-metal catalyst; at catalysis Friedel-Crafts acylation reaction, the cyclisation of nitrile and alkynes and CO ₂Progress significantly makes the research of graphite mould carbonitride more and more receive domestic and international investigators' concern in the priming reaction.

At present the synthetic method of graphite mould carbonitride mainly contains two classes, i.e. high temperature pyrolytic cracking (HTP) and solvent-thermal method, and wherein high temperature pyrolytic cracking (HTP) can be made by high temperature pyrolytic cracking (HTP) (500-1000 ℃) by the multiple C of containing, N raw materials such as trimeric cyanamide, cyanamide, cyanuryl chloride and quadrols.But final product is difficult to separate and purifies because the pyrolytic process intermediate product is more, often is difficult to obtain the g-C of pure phase ₃N ₄, limited its application as further synthetic precursor.And solvent-thermal method synthetic reaction condition comparatively gentle (200-400 ℃), nitrogen is difficult for running off, and makes reactant that the reaction of stoichiometric ratio can take place with solvent as medium, selects suitable solvent, helps separating, purifying, obtains the g-C of intimate stoicheiometry ₃N ₄The solvent thermal of report is synthesized g-C at present ₃N ₄Mainly lay particular emphasis on the exploration of synthetic product condition and the structural analysis of product, solvent adopts poisonous and dangerous hydrazine and liquefied ammonia, the autoclave pressure volume has only 50-100ml, sample throughput is very little, do not consider amplificationization as a kind of mass production processes of critical function material, and after output is amplified, the change meeting of factors such as corresponding mass transfer, heat transfer directly influences the stability of quality product, and the operating procedure that this patent relates in the batch preparations graphite mould carbonitride specifically comprises best synthetic technological condition, proportioning raw materials, agitation condition etc.

Summary of the invention

The object of the invention provides a kind of simple to operate, safety, mild condition, can obtain the preparation method of pure phase graphite mould carbonitride in batches, and this material can be used for obtaining the synthetic precursor of high-density carbonitride and support of the catalyst, photocatalyst.

Benzene solvent thermal synthesis concrete steps of the present invention are as follows:

(1) weighing is some near the raw material of stoichiometric ratio, comprises C ₃N ₃Cl ₃And NaNH ₂Powder is measured the solvent of the 60-70% of reactor volume (0.2-1.0L) again, adds the certain volumetrical reactor of band teflon-lined;

(2) the certain temperature rise rate of control (5-20 ℃/min), be warmed up to design temperature (180-230 ℃), the stirring velocity (100-300rpm) of control reactor.When reaching temperature required, isothermal reaction 10-20h.

(3) after heating finishes, naturally cool to room temperature, take out sample, carry out ultrasonic concussion, water and washing with acetone several times again are to remove inorganic salt and the organism in the product, decompress filter, then product is put into baking oven and dry, obtain yellow powder, be the purpose product.

Have the following advantages according to preparation method of the present invention:

(1) simple to operate, the mild condition of preparation method of the present invention, cost are low, prepare graphite mould carbonitride well-crystallized, purity height, output big (＞10g), be applicable to experiment study on the synthesis and performance characterization to further preparation magnanimity high-density carbonitride phase.

(2) synthetic graphite type carbonitride of the present invention has good impact stability,＜40GPa, still do not decompose under the pressure of＜3000K, the temperature condition.

Description of drawings

The g-C of Fig. 1 embodiment 2 ₃N ₄XRD figure spectrum

The g-C of Fig. 2 embodiment 2 ₃N ₄The TEM photo

Embodiment

Embodiment 1

(1) takes by weighing 9.2g C ₃N ₃Cl ₃With 6.2g NaNH ₂Powder is measured 70% solvent of reactor volume (0.2L) again, adds the certain volumetrical reactor of band teflon-lined;

(2) be warmed up to 190 ℃, isothermal reaction 12h;

(3) after heating finishes, naturally cool to room temperature, take out sample, carry out ultrasonic concussion, water and washing with acetone are three times again, to remove inorganic salt and the organism in the product, decompress filter, then product is put into 50 ℃ of oven dry of baking oven 4h, obtained yellow powder, be the purpose product.

Embodiment 2

(1) weighing 11.5g C ₃N ₃Cl ₃And 7.73gNaNH ₂Powder is measured 70% solvent of reactor volume (0.25L) again, adds band teflon-lined reactor;

(2) the certain temperature rise rate of control (20 ℃/min), be warmed up to design temperature (220 ℃), the stirring velocity of control reactor control is 220rpm, isothermal reaction 15h;

Embodiment 3

(1) weighing 31.2g C ₃N ₃Cl ₃And 46.0gNaNH ₂Powder is measured 75% solvent of reactor volume (1.0L) again, adds band teflon-lined reactor;

(2) the certain temperature rise rate of control (15 ℃/min), be warmed up to design temperature (215 ℃), the stirring velocity of control reactor control is 300rpm, isothermal reaction 20h;

Claims

1. the solvent process for thermosynthesizing of the graphite mould carbonitride of synthetic precursor that is used to obtain the high-density carbonitride and support of the catalyst, photocatalyst is characterized in that its chemical constitution is:

C _xN _yH _z

Wherein x, y, z are each atoms of elements number in the above-mentioned molecular formula, x=2.8-3.2, y=4-5, z=1-5.

2. the preparation method of batch pure phase graphite mould carbonitride according to claim 1 is characterized in that this method may further comprise the steps:

(1) weighing is some near the raw material of stoichiometric ratio, comprises C ₃N ₃C1 ₃And NaNH ₂Powder is measured the solvent of the 60-70% of reactor volume (0.2-1.0L) again, adds the certain volumetrical reactor of band teflon-lined;

(2) the certain temperature rise rate of control (5-20 ℃/min), be warmed up to design temperature (180-230 ℃), the stirring velocity (100-300rpm) of control reactor control.When reaching temperature required, isothermal reaction 10-20h.

3. preparation method according to claim 2 is characterized in that, described solvent is one of benzene, alkylbenzene.

4. preparation method according to claim 2 is characterized in that carbon nitride material comprises to be approximately C ₃N ₄Chemical molecular formula and graphite-like structure.