CN1887421A

CN1887421A - Process and apparatus for preparing metal nitride catalyst material

Info

Publication number: CN1887421A
Application number: CN 200510046779
Authority: CN
Inventors: 吴杰; 李铁藩; 熊天英; 金花子
Original assignee: Institute of Metal Research of CAS
Current assignee: Institute of Metal Research of CAS
Priority date: 2005-06-29
Filing date: 2005-06-29
Publication date: 2007-01-03
Anticipated expiration: 2025-06-29
Also published as: CN100391606C

Abstract

The present invention relates to catalyst technology, and is especially process and apparatus for preparing metal nitride catalyst material (gamma-Mo2N). MoO3/TiO2, MoO3/NiO-TiO2, MoO3/Al2O3-TiO2 or MoO3/Al2O3 is set in a reactor to replace MoO3 with reducing N2-H2 so as to prepare supported metal nitride catalyst Mo2N/TiO2, Mo2N/NiO-TiO2, Mo2N/Al2O3-TiO2 or Mo2N/Al2O3. The reaction conditions include N2-H2 ratio in the gas mixture of 1/(3-5), reaction temperature of 933K+/-10K and holding time of 0.5-1 hr. The apparatus includes mainly a mixer, a reactor, a heat exchanger, and a gas chromatogaph connected through pipeline. The present invention can prepare gamma-Mo2N with specific surface area as great as 150 sq m/g, and the preparation process has its operation simpler than that with NH3.

Description

Preparation method of metal nitride catalytic material and special equipment thereof

Technical Field

The invention relates to the technical field of catalytic materials, in particular to a metal nitride (gamma-Mo)₂N) preparation method of catalytic material and its special equipment.

Background

It is known that nitrides and carbides of transition metals are present in NH₃The catalyst has the same catalytic activity as that of the traditional noble metal (Pt, Ru and the like) catalyst in the aspects of synthesis and the like, and even has higher catalytic activity. Gamma-Mo₂N as heterogeneous catalytically active material has higher cracking activity on heteroatom (N, S, O) containing rings and lower hydrogenation activity on aromatic rings than common commercial transition metal Ni, Co, Mo, W catalysts and the like in many systems of hydrogenation and hydrofinishing, such as gamma-Mo₂N-p-dibenzothiophene Hydrodesulfurization (HDS). Industrial Mo of activity ratio₂S/Al₂O₃The catalyst is 1.2 times higher, and the performance of Hydrodenitrogenation (HDN) is excellent. And found that gamma-Mo₂N and Pd/Al₂O₃The selectivity of the catalysis being different, e.g. acetylene over Pd/Al₂O₃Catalytic conversion to ethane, whereas gamma-Mo₂N is selectively hydrogenated to ethylene (95%).

gamma-Mo for foreign country₂The preparation and application of N in catalytic reactions has been studied for over 30 years. The research is carried out in 90 years in China, and is in the laboratory research stage. Mostly prepared by a small reactor, Mo₂The N amount is between 0.5 grams and several grams.

γ-Mo₂N as a catalyst must have a high surface area to volume ratio. To achieve this, there are two approaches: one is to directly prepare Mo with high specific surface area₂N material; secondly, the gamma-Mo with catalytic activity₂N is supported on a porous support. Early study of multiple harvestsUsing the first approach. In recent years, for load type gamma-Mo₂N has also been studied with new progress.

The preparation of molybdenum nitride can be traced back to Henderson et al (1908) using NH₃Reacting with molybdenum (Mo) at 850 deg.C to obtain molybdenum nitride, and reacting with NH in Xiagg (H ä gg) (1930)₃And reacting with Mo to establish a Mo-N binary equilibrium phase diagram. Mo powder and NH₃Reacting at 400-720 ℃ for 4-24 hours to obtain a product containing 0.77-7.15% of nitrogen, and obtaining 11.95% of nitrogen after long-time (120 hours) nitridation treatment at 400 ℃, wherein the molybdenum nitride has three phases of β -Mo₃N、γ-Mo₂N, delta-MoN, wherein β -Mo₃Scurberg (Sch Ö nberg) reacting molybdenum powder in nitrogen at 800 deg.C for several hours also yielded the product with the highest nitrogen content (49.6 at%), MoCl was used in addition to the metal molybdenum powder as the starting material₃Or MoCl₅And NH₃The molybdenum nitride is prepared by reaction at low temperature (340 ℃). However, the surface area S of molybdenum nitride produced by a classical high temperature nitriding process_g＜1m²The/g does not satisfy the catalytic requirements.

For the preparation of high surface/volume ratio gamma-Mo₂N, so over the course of time, much research has been devoted to developing unsupported, high surface area gamma-Mo₂And N is added. Gepman (Kiperman) exploration for Mo preparation by reaction of ammonium molybdate and ammonia at 873-923K₂N, but they did not measure S_gMoO for Hilis et al₂As a precursor, use H first₂Partial reduction followed by N₂In (773K) nitriding, Aika et al with MoO₃And NH₃Nitriding at constant temperature to obtain a surface area of 13.5m²Dark grey Mo/g₂And (4) N powder.

Volpe (Volpe), Aoyama (Oyama) and Boudart (1983) first proposed the use of temperature programming to render MoO₃And NH₃Reacting to obtain the product with high specific surface area (S)_g＝190m²gamma-Mo of/g)₂And N is added. Their method was to use 1 gram MoO₃With a flow rate of 70. mu. mol. S^-1Pure NH of₃And (4) reacting. The temperature raising program is divided into three stages: (1) rapidly heating from room temperature to 690K (417 ℃);(2)690K-740K (467 ℃) and a heating rate of 0.01KS^-1(3) the rate of temperature rise from 740K to 979K (706 ℃ C.) was 0.05KS^-1And keeping the constant temperature for 0.5 hour to prepare Mo₂Surface area S of N_g＝190 m²/g。

Rolpe (Rolpe) and Boolean (Bourlat) (1985) using MoO with temperature programmed₃With WO₃As raw material and NH₃Reacting to obtain a product with high specific surface area; mo₂S of N_g＝220m²g^-1，W₂S of N_g＝91m²g^-1The grain sizes were 3nm and 4nm, respectively. Providing MoO₃And NH₃The reaction is a local chemical reaction (Topotatic reaction), so MoO₃And Mo₂And a crystallographic orientation relation exists between N: [010]_MoO3//[100]_Mo2NReaction product Mo₂The morphology of N is MoO₃The research result of the flaky pseudomorphic body is that the flaky pseudomorphic body is like a porous monocrystal, the average pore diameter is less than 3nm, and the research result is that the gamma-Mo with no supporter and high specific surface area is prepared₂N opens up a new technical route, namely a temperature programmed reaction technology.

TiO for southern Kao university₂Roasting the carrier at the temperature of 300-500 ℃ for 3-5 hours, weighing equal volume ammonium molybdate according to the measurement, soaking at room temperature for 4-12 hours, filtering, drying at the temperature of 100-120 ℃, roasting at the temperature of 300-500 ℃ for 3-5 hours, tabletting and molding, and performing temperature programming under the ammonia atmosphere to prepare Mo₂N (patent No. 00103352.2). However, the MoO adopting temperature programming is reported at present₃And NH₃Reaction for preparing Mo₂The amount of N is small (from 0.5 grams to several grams). For more than 90 years, the study of NH has been performed by West and Markel₃The basic principle and dynamics of synthesis and decomposition and the basis of catalytic performance, the research of NH is emphasized₃With MoO₃In a quartz tubular reactor, the reaction temperature is related to the reaction product and the surface area. Polycrystalline MoO when the temperature rises to 473K₃Fragmentation, slight increase in surface area, presence of unknown phase (804pm) and MoO at 573K₃，673K MoO₃Disappearance and appearance of MoO₂And another unknown phase (621, 307 and 205pm), more than 773K forming Mo₂N, MoO, increasing with increasing temperature₂The amount of (c) is reduced. The reaction is carried out for 980K +2hr at constant temperature, the reduction nitridation reaction is complete, and the reaction product is completely converted into gamma-Mo₂And N is added. But gamma-Mo₂The crystal grains of N grow larger, and the surface area is slightly reduced. From this, it was concluded that MoO₃And NH₃The maximum temperature of the temperature program is 980K, and the temperature should be kept constant for 2 hours to ensure the reaction is complete. In the calculation of the bed temperature of the tubular reactor, it was found that the center temperature was 120K lower than the furnace temperature, the radial temperature was 80K lower, and the surface temperature of the bed was 40K lower than the furnace temperature, even though the inner diameter was 4mm and the length was 1m, the MoO of the tubular furnace₃The loading of (a) was only 0.5 grams, actually measured at 35K with a hot well, and both were substantially identical. And the temperature gradient of the tube furnace with the diameter of 25cm can reachHundreds of degrees, it can be concluded that Mo is prepared in large quantities₂N, the control of bed temperature is a very difficult problem. In the presence of NH₃When used as a nitriding reactant, there are two key problems affecting product quality: firstly, reduction of MoO₃Water generation ( ) The presence of water vapor promotes Mo as a product₂N is hydrothermally sintered, and H₂O and H₂In MoO₃Competitive adsorption of Mo₂The surface area of N is reduced; second is NH₃Decomposition into endothermic reaction results in very uneven bed temperature distribution in the reactor and large axial and radial temperature gradients.

Disclosure of Invention

In order to solve the problems, the invention provides a preparation method of a metal nitride catalytic material and special equipment thereof, wherein mixed gas of nitrogen and hydrogen is used as a reduction nitridation reactant, and MoO added with mixed filler is used₃Reaction for preparing Mo₂N, to completely avoid NH₃The problem of bed temperature gradient caused by heat absorption by decomposition, and Mo caused by steam₂N causes a problem of hydrothermal sintering.

The technical scheme of the invention is as follows:

a process for preparing the catalytic metal nitride material includes such steps as mixing MoO₃/TiO₂、MoO₃/NiO-TiO₂、MoO₃/Al₂O₃-TiO₂Or MoO₃/Al₂O₃Placing into a reactor, and carrying out N₂-H₂Reductive replacement of MoO₃To prepare Mo₂N/TiO₂、Mo₂N/NiO-TiO₂、Mo₂N/Al₂O₃-TiO₂Or Mo₂N/Al₂O₃A supported metal nitride catalyst; n is a radical of₂-H₂Volume ratio of mixed gas: h₂/N₂＝(3-5)/1，N₂-H₂The space velocity of the mixed gas is 6,000-^-1The reaction temperature is 933K +/-10K, and the heat preservation time is 0.51 hour.

The temperature control process in the reactor of the invention is as follows:

1) rapidly heating from room temperature to 673K at a heating rate of 1-50K/min;

2)673 heating at 0.6-1K/min with 933K;

3)933K + -10K keeping the temperature for 0.5-1 hr;

4) cooled to room temperature in the reactor.

The invention can switch N at room temperature₂-H₂The mixed gas is 99% Ar-1% O by volume ratio₂The mixed gas is used for 12-24 hours.

A special device for preparing metal nitride catalytic material comprises a mixer, a heat exchanger, a water cooler, a separator, a reactor, a drying part, a compressor, an intersegmental cooler, a gas chromatograph and a planar six-way valve; the mixer enters the reactor through a pipeline, the outlet of the reactor enters the heat exchanger through a pipeline, on one hand, the heat exchanger enters the mixer through a pipeline, and the pipeline is connected to the gas chromatograph through the plane six-way valve; on the other hand, the water-cooled gas enters a water cooler through a pipeline, a separator enters a compressor through a drying part through a pipeline, the outlet of the compressor is connected with a heat exchanger through a pipeline, and an intersegment cooler is respectively connected with an inlet pipeline and an outlet pipeline of the compressor.

The mixer of the invention enters the reactor through the pipeline, the pipeline is provided with a check valve and is connected with a pressure display instrument and a needle valve, the inlet of the reactor is provided with a temperature control display instrument and a temperature display instrument, the outlet of the reactor is divided into two paths, one path enters the heat exchanger through the pipeline, the other path leads to the atmosphere through the pipeline, and the pipeline is provided with a stop valve; on one hand, the heat exchanger enters the mixer through a pipeline, the pipeline is connected with a needle valve, and the needle valve are connected in parallel and then are connected to a gas chromatograph through a plane six-way valve; the other side of the heat exchanger enters a water cooler through a pipeline, the pipeline is provided with a temperature display instrument, the water cooler is communicated with the atmosphere through a separator and a pipeline, the pipeline is provided with a stop valve, the separator enters a compressor through a drying part through a pipeline, the pipeline is provided with a temperature control display instrument, the drying part is formed by connecting a dryer IA and a dryer IB which are connected in series in parallel with a dryer IIA and a dryer IIB which are connected in series, the dryer IA, the dryer IB, the dryer IIA and the dryer IIB are respectively connected with the temperature control display instrument, inlet valves and regeneration waste gas outlet valves are respectively arranged at inlets of the dryer IA and the dryer IIA, an outlet valve and a regeneration nitrogen inlet valve are respectively arranged at outlets of the dryer IB and the dryer IIB, and a pressure display instrument, a check valve and a stop valve are; the outlet of the compressor is connected with the heat exchanger through a pipeline, a stop valve and a mass flow meter are arranged on the pipeline, the intersegmental cooler is respectively connected with the inlet pipeline and the outlet pipeline of the compressor, and the pipeline connected with the outlet of the compressor is provided with the stop valve and the check valve.

The invention has the following advantages:

(1) the invention adopts N₂-H₂Mixed gas substituted NH₃With MoO₃And (3) reacting, wherein when the reaction temperature is about 660 ℃ and the temperature rise speed is 0.6-1K/min, the airspeed is increased, and the surface area of the product is increased. Hydrogen rich N₂-H₂Mixed gas (H)₂/N₂3-5/1), space velocity of 6,000-^-1High surface area Mo can be obtained₂And N is added. The invention can prepare the product with the specific surface area as high as 150m²gamma-Mo of/g₂N；

(2) The reaction gas is dried for recycling, the utilization rate is 100 percent, and the cost is low;

(3) using NH in the invention₃The operation is simplified, and the operation danger and the environmental pollution are eliminated;

(4) the invention adopts N₂-H₂Mixed gas and added mixed filler eliminate NH₃The decomposition endotherm causes the problem of temperature gradient caused by poor heat conduction of the reaction bed. Thereby mass production of Mo₂And (4) N powder.

Drawings

FIG. 1 is a flow chart of a molybdenum nitride batch synthesis apparatus. In the figure, 1 mixer; 2, a heat exchanger; 3, a water cooler; 4, a separator; 5, a reactor; 6a dryer IA; 7 a dryer IB; 8, a dryer IIA; 9 a dryer IIB; 10 compressor, 11 interstage cooler; 12 gas chromatography; 13 plane six-way valve.

FIG. 2 is a schematic view of the temperature rising system used in the present invention.

Detailed Description

The invention relates to gamma-Mo₂The preparation technique of N is explained in detail.

In view of preparing gamma-Mo with high specific surface area₂N, the invention adopts a way of temperature programmed gradual reaction and utilizes N₂Reduction of MoO as a reducing gas₃. The accumulation of the moisture of the product is prevented by controlling the temperature rise speed and increasing the gas flow; in order to reduce gas consumption, a gas circulation device is designed in the system so as to reduce preparation cost.

The batch molybdenum nitride reaction apparatus is shown in fig. 1.

A gas

1, nitrogen-high purity nitrogen (the concentration is 99.999%), nitriding raw materials come from a steel cylinder and go to a mixer;

2, hydrogen-high purity hydrogen (the concentration is 99.999%), nitriding raw materials come from a steel cylinder and go to a mixer;

3, mixed gas, which is formed by mixing nitrogen, hydrogen and circulating gas, is subjected to heat exchange and denitrification reaction;

4, cooling the reaction gas, namely the gas discharged from the nitriding reactor, to a dryer;

5, drying gas, namely gas (gas out of the dryer) after being dried and dehydrated, enters the inlet of the compressor;

6, circulating gas, namely gas pressurized by a compressor (gas discharged from the compressor), cooling and then sending to a mixer;

7 regenerating nitrogen, namely high-purity nitrogen (the concentration is 99.999 percent), from a steel cylinder and removing the nitrogen from a dryer;

8, directly discharging regenerated waste gas, namely nitrogen containing moisture removed by the regeneration of the drying agent;

9 feedback gas-gas from the compressor outlet directly to the compressor inlet.

Second, equipment

1 mixer-mixing nitrogen, hydrogen, recycle gas, stainless steel;

2, a heat exchanger, namely heat exchange is carried out on reaction gas and circulating gas, the stainless steel shell has the diameter of 108mm, and a spiral corrugated pipe is arranged in the stainless steel shell; tube pass: reaction gas; shell pass: circulating gas;

3 water cooler-cooling the reaction gas after the heat exchanger, stainless steel, shell diameter 108mm, and installing a coiled corrugated pipe;

tube pass: reaction gas; shell pass: cooling water;

4 separator for separating condensed water;

5 reactor-fixed bed, catalyst precursor molybdenum oxide, thermocouple, L1150 mm phi, 42mm x 3mm, thermocouple sleeve, heating electric furnace 4 KW;

6 dryer IA-fixed bed adsorber, silica gel is filled in, L is 750mm, phi 42mm x 3mm, electric furnace 2 KW;

7 dryer IB-fixed bed adsorber, built-in molecular sieve, L is 550mm, phi 42mm x 3mm, electric furnace 2 KW;

8 dryer IIA-fixed bed adsorber, silica gel is filled in, L is 750mm, phi 42mm is multiplied by 3mm, electric furnace 2 KW;

9 drier IIB-fixed bed adsorber, built-in molecular sieve, L is 550mm, phi 42mm x 3mm, electric furnace 2 KW;

10 compressor-reciprocating compressor, discharge pressure not more than 0.55 MPa;

11 interstage coolers for cooling the feedback gas;

12 gas chromatograph-model GC9800TP, FID, TCD detector: stationary phase TDX-02, d is 3 mm;

helium is formed by separating circulating gas and mixed gas;

13 plane six-way valve-for gas analysis sampling.

Third, instrument, valve and legend

3.1

A mass flow meter and a mass flow controller;

FIC-1 control shows nitrogen flow;

FIC-2 controls and displays hydrogen flow;

3.2a mass flow meter;

FI-1 shows the circulating gas flow rate;

3.3a non-return valve;

3.4

a needle valve;

SA-for mixture analysis;

SB-for cycle gas analysis;

3.5

a stop valve;

v1 — for draining condensed water;

v2-for system air defense;

v3 — for adjusting feedback gas flow;

v4 — for adjusting compressor inlet flow;

v5 — for adjusting compressor outlet flow;

i-1 and II-1 are inlet valves (for adsorption) of dryers IA and IIA;

II-4 and I-4 are outlet valves of IB and IIB of the dryer (for adsorption);

i-5 and II-5 are regeneration nitrogen inlet valves (for desorption) of driers IB and IIB;

i-2 and II-2 are regeneration waste gas outlet valves (for desorption) of the dryers IA and IIA;

TIC temperature control display instrument;

a TIC-1SR53 temperature controller for controlling the temperature of the nitriding reactor (solid state relay);

TIC-2 temperature controller (PID regulation), control dryer IA (solid state relay);

TIC-3 temperature controller (PID regulation), control dryer IB (solid state relay);

TIC-4 temperature controller (PID regulation), control dryer IIA (solid state relay);

a TIC-5 temperature controller (PID regulation) for controlling a dryer IIB (solid state relay);

a TI temperature display instrument;

TI-1 shows the nitridation reactor bed temperature;

TI-2 shows the temperature of the reaction gas at the outlet of the heat exchanger;

TI-3 shows the temperature of the reaction gas at the outlet of the water cooler;

a PI pressure display instrument;

PI-1 shows the nitridation reactor inlet pressure;

PI-2 shows the dryer outlet pressure;

as shown in fig. 1, the apparatus of the present invention comprises: the system comprises a mixer 1, a heat exchanger 2, a water cooler 3, a separator 4, a reactor 5, a dryer IA6, a dryer IB7, a dryer IIA8, a dryer IIB9, a compressor 10, an interstage cooler 11, a gas chromatograph 12 and a plane six-way valve 13. N is a radical of₂、H₂The reactor is respectively communicated with a mixer 1 through a mass flow meter and mass flow controllers FIC-1 and FIC-2, the mixer 1 enters a reactor 5 through a pipeline, the pipeline is provided with a check valve and is connected with a pressure display instrument PI-1 and a needle valve SA through pipelines, a temperature control display instrument TIC-1 and a temperature display instrument TI-1 are arranged at the inlet of the reactor 5, the outlet of the reactor 5 is divided into two paths, one path enters a heat exchanger 2 through the pipeline, the other path is communicated with the atmosphere through the pipeline, and the pipeline is provided with a stop valve V2; the heat exchanger 2 on the one hand enters the mixer 1 via a line which is connected to a needle valve SB, the needle valve SA and the needle valve SB being connected in parallel and then passing through a plane six-way valve 13 to the mixerA gas chromatograph 12; the heat exchanger 2 on the other hand enters the water cooler 3 through a pipeline, the pipeline is provided with a temperature display instrument TI-2, the water cooler 3 is communicated with the atmosphere through a separator 4 through a pipeline, the pipeline is provided with a stop valve V1, the separator 4 enters a compressor 10 through a pipeline through a drying part, the pipeline is provided with a temperature control display instrument TI-3, the drying part is formed by connecting a dryer IA6 and a dryer IB7 which are connected in series in parallel with a dryer IIA8 and a dryer IIB9 which are connected in series, the dryer IA6, the dryer IB7, the dryer IIA8 and the dryer IIB9 are respectively connected with a temperature control display instrument TIC-2, TIC-3, TIC-4 and TIC-5, inlet valves I-1 and II-1 and regenerated waste gas outlet valves I-2 and II-2 are respectively arranged at inlets of the dryer IA6 and the dryer IIA8, outlet valves II-4 and dryer IB7 and dryer 9 are respectively provided with an outlet valve II-4 and IIB-, I-4 and regeneration nitrogen inlet valves I-5 and II-5, wherein a pressure display instrument PI-2, a check valve and a stop valve V4 are arranged on a pipeline connecting the drying part and the inlet of the compressor 10; the outlet of the compressor 10 is connected with the heat exchanger 2 through a pipeline, a stop valve V5 and a mass flow meter FI-1 are arranged on the pipeline, the inter-segment cooler 11 is respectively connected with the inlet and the outlet of the compressor 10, and a stop valve 3 and a check valve are arranged on the pipeline connecting the inter-segment cooler 11 and the outlet of the compressor 10.

Fourthly, the process flow is as follows:

nitrogen and hydrogen from the steel cylinder enter the mixer 1 through the mass flow controller and are mixed with the circulating gas (unreacted nitrogen and hydrogen) from the compressor 10 to form a certain hydrogen-nitrogen ratio (proportion range H)₂/N₂And (3-5)/1) enters a reactor 5, the temperature is controlled by an SR53 temperature controller, and molybdenum oxide reacts to generate molybdenum nitride under a certain temperature condition according to a set temperature rise program. Unreacted gas is discharged from an outlet of the nitriding reactor, sequentially enters a heat exchanger 2 and a water cooler 3, is subjected to condensation water separation by a separator 4, then enters a dryer for deep dehydration, and then enters a compressor 10 for pressurization and then returns to the system.

Fifthly, the operation steps are as follows: (for example, dryer IA, IB are used for adsorption and dryer IIA, IIB are regenerated)

1) Open color spectrum

Opening a main valve of the steel cylinder, and adjusting a partial pressure valve to be about 0.15-0.2 MPa;

switching on a main power supply of the gas chromatograph, and adjusting the front pressure of the column to be 0.15 MPa;

opening a chromatographic workstation and connecting a passage B (the workstation is divided into two passages, and can detect two paths of gas simultaneously, because only one passage is used, namely the passage B);

2) temperature rise

Setting and heating to 130 ℃ of a column box, 140 ℃ of a detection chamber TCD and 160 ℃ of a sample injector;

a stable temperature (no less than 0.5 hour with a linear base);

opening a bridge current switch, and adjusting to 120-130 mA;

standby;

3) a control panel power main switch is turned on (a heat exchange/water cooling temperature display instrument is turned on); opening mass flow meters including FIC-1, FIC-2 and FI-1;

airtight test (can be carried out in a whole system or in sections);

closing SA, SB, V1, V2, V3, I-1, II-4, I-2, II-2, I-5, II-5 (right to bottom);

full-open V4, V5, II-1 and I-4;

opening an N2 gas steel cylinder, and adjusting a partial pressure valve to 0.25 MPa;

adjusting FIC-1, and introducing nitrogen into the system at a flow rate of 20-28L/min;

maintaining pressure and testing leakage, after the system pressure is balanced (the system is full of gas), the FIC value falls back and is not more than 2L/min, otherwise, detecting leakage by using leakage liquid, finding a leakage point and processing (screwing) in time;

opening I-1 and II-4 completely, closing II-1 and I-4 and repeating ④⑤;

FIC-1 is turned off (to indicate a value of 0);

4) temperature rise

Connecting TIC-1(SR53), setting the temperature according to a temperature-raising program, and raising the temperature of the nitridation reactor until the bed layer reaches a first set temperature point (TI-1 is shown to meet the first-stage temperature rise); preparing ventilation preparation at the same time;

5) ventilation

Adjusting FIC-1 according to the hydrogen-nitrogen ratio, introducing nitrogen into the system at a flow rate of 20L/min, adjusting FIC-2 to introduce corresponding hydrogen into the system at a corresponding flow rate (the pressure is the same as that of the nitrogen after the pressure of a hydrogen steel cylinder is reduced), and stopping until the indication values of FIC-1 and FIC-2 fall to the specified value (less than 2L/min); the pressure of PI-1 and PI-2 is not changed any more, and is close to the pressure of the inlet and outlet of the compressor after the pressure of the steel cylinder is reduced;

6) starting the compressor and establishing a cycle

7) Analysing gas composition

And (3) mixed gas analysis:

starting the SA;

sampling (full displacement) (six-way valve left and right);

sample introduction (six-way valve is towards left and right);

closing the SA;

and (3) circulating gas analysis:

opening the SB;

sampling (full displacement) (six-way valve left and right);

sample introduction (six-way valve is towards left and right);

closing the SB;

8) adjusting composition

The flow entering the system is adjusted by fine tuning the pressure;

9) starting compressor

After the FI-1 flow is normal, under the condition of full opening of V3:

① if the flow is increased, the pressure (N2, H2 are adjusted simultaneously) Pmax after the pressure of the steel cylinder is reduced is less than or equal to 0.38 MPa;

② if the flow is reduced, the V4 valve is closed;

10) normal experiment

The gas composition is analyzed, and the flow is adjusted according to the analyzed gas composition.

Sixthly, normal parking

1) Stopping the compressor;

2) stopping the electric furnace;

3) closing the hydrogen main pressure valve and closing the nitrogen main pressure valve;

4) opening V5, and releasing pressure of the system;

seven, closing the chromatogram

1) Closing the bridge flow;

2) turning off the heating power supply;

3) turning off the detector power supply;

4) turning off the carrier gas when the temperature of the detector is lower than 70 ℃;

eighth, dryer switching

If the dryer I series is changed from adsorption to regeneration, the dryer II series is changed from standby to normal operation;

opening II-1 and I-4 fully, and closing I-1 and II-4;

connecting a dryer IA and a dryer IB, and setting the dryer IA at 140 ℃; a dryer IB 350 ℃;

opening I-2 and I-5;

introducing regenerated nitrogen (only by gas passing);

air distribution system ○ N₂-H₂Mixed gas, ○ Ar-O₂(1％O₂) Compounding, attaching a flowmeter, a pressure reducing valve, a regulating valve and sampling analysis.

Example 1

The programmed temperature system adopted by the invention is shown in figure 2, and the optimal programmed temperature system comprises the following steps:

1. the temperature is rapidly increased from room temperature to 673K, and the temperature increasing speed is 1-50K/min (25K/min in the embodiment);

2.673-933K is heated at a speed of 0.6-1K/min (0.6K/min in the embodiment);

3.933K is kept constant for 0.5-1hr (1 hr in this example);

4. cooling to room temperature in the reactor;

5. switching N at room temperature₂-H₂The mixed gas is 99% Ar-1% O by volume ratio₂The mixed gas (i.e. passivation treatment) is carried out for 12-24 hr, in this embodiment 24 hr.

The invention relates to gamma-Mo₂The N supported catalyst was prepared as follows:

respectively adding MoO according to the above process₃/TiO₂、MoO₃/NiO-TiO₂、MoO₃/Al₂O₃-TiO₂Or MoO₃/Al₂O₃Put into the reactor of the invention to carry out N₂-H₂Reduction and replacement of MoO₃To prepare Mo₂N/TiO₂、Mo₂N/NiO-TiO₂、Mo₂N/Al₂O₃-TiO₂Or Mo₂N/Al₂O₃A supported metal nitride catalyst. N is a radical of₂-H₂Volume ratio of mixed gas: h₂/N₂＝4/1，N₂-H₂The space velocity of the mixed gas is 6,000-^-1(50,000 h in this example)^-1) Detection of gamma-Mo by X-ray diffraction₂The existence of N, the specific surface area of which is up to 150m²/g。

Example 2

The difference from the embodiment 1 is that:

1. rapidly heating from room temperature to 673K at a heating rate of 1K/min;

2.673-933K is heated up at a speed of 0.8K/min;

3.933K maintaining the temperature for 0.8 hr;

4. cooling to room temperature in the reactor;

5. switching N at room temperature₂-H₂The mixed gas is 99% Ar-1% O by volume ratio₂The mixed gas (i.e., passivation treatment) was set for 12 hr.

respectively adding MoO according to the above process₃/TiO₂、MoO₃/NiO-TiO₂、MoO₃/Al₂O₃-TiO₂Or MoO₃/Al₂O₃Put into the reactor of the invention to carry out N₂-H₂Reductive replacement of MoO₃To prepare Mo₂N/TiO₂、Mo₂N/NiO-TiO₂、Mo₂N/Al₂O₃-TiO₂Or Mo₂N/Al₂O₃A supported metal nitride catalyst. N is a radical of₂-H₂Volume ratio of mixed gas: h₂/N₂＝3/1，N₂-N₂The space velocity of the mixed gas is 6,000h^-1Detection of gamma-Mo by X-ray diffraction₂NHas a specific surface area of 130m²/g。

Example 3

The difference from the embodiment 1 is that:

1. rapidly heating from room temperature to 673K at a heating rate of 50K/min;

2.673-933K adopts 1K/min speed to heat up;

3.933K maintaining the temperature for 0.5 hr;

4. cooling to room temperature in the reactor;

5. switching N at room temperature₂-H₂The mixed gas is 99% Ar-1% O by volume ratio₂The mixed gas (i.e., passivation treatment) was 18 hr.

respectively adding MoO according to the above process₃/TiO₂、MoO₃/NiO-TiO₂、MoO₃/Al₂O₃-TiO₂Or MoO₃/Al₂O₃Put into the reactor of the invention to carry out N₂-H₂Reductive replacement of MoO₃To prepare Mo₂N/TiO₂、Mo₂N/NiO-TiO₂、Mo₂N/Al₂O₃-TiO₂Or Mo₂N/Al₂O₃A supported metal nitride catalyst. N is a radical of₂-H₂Volume ratio of mixed gas: h₂/N₂＝5/1，N₂-H₂The space velocity of the mixed gas is 10,000h^-1Detection of gamma-Mo by X-ray diffraction₂The existence of N, the specific surface area of which is up to 140m²/g。

MoO in the invention₃/TiO₂In a weight ratio of MoO₃∶TiO₂＝1∶5；

MoO in the invention₃/NiO-TiO₂In a weight ratio of MoO₃∶NiO∶TiO₂＝1∶5∶1；

MoO in the invention₃/Al₂O₃-TiO₂In a weight ratio of MoO₃∶Al₂O₃∶TiO₂＝1∶5∶1；

MoO in the invention₃/Al₂O₃In a weight ratio of MoO₃∶Al₂O₃＝1∶5。

Claims

1. A preparation method of a metal nitride catalytic material is characterized by comprising the following steps: adding MoO₃/TiO₂、MoO₃/NiO-TiO₂、MoO₃/Al₂O₃-TiO₂Or MoO₃/Al₂O₃Placing into a reactor, and carrying out N₂-H₂Reductive replacement of MoO₃To prepare Mo₂N/TiO₂、Mo₂N/NiO-TiO₂、Mo₂N/Al₂O₃-TiO₂Or Mo₂N/Al₂O₃A supported metal nitride catalyst; n is a radical of₂-H₂Volume ratio of mixed gas: h₂/N₂＝(3-5)/1，N₂-H₂The space velocity of the mixed gas is 6,000-^-1The reaction temperature is 933K +/-10K, and the heat preservation time is 0.5-1 hour.

2. A method for preparing a metal nitride catalytic material according to claim 1, characterized in that the temperature control process in the reactor is as follows:

2)673 heating at 0.6-1K/min with 933K;

3)933K + -10K keeping the temperature for 0.5-1 hr;

4) cooled to room temperature in the reactor.

3. A method of making a metal nitride catalytic material as set forth in claim 2, characterized in that: switching N at room temperature₂-H₂The mixed gas is 99% Ar-1% O by volume ratio₂The mixed gas is used for 12-24 hours.

4. A special equipment for preparing metal nitride catalytic material is characterized in that: comprises a mixer (1), a heat exchanger (2), a water cooler (3), a separator (4), a reactor (5), a drying part, a compressor (10), an intersegmental cooler (11), a gas chromatograph (12) and a plane six-way valve (13); the mixer (1) enters the reactor (5) through a pipeline, the outlet of the reactor (5) enters the heat exchanger (2) through a pipeline, on one hand, the heat exchanger (2) enters the mixer (1) through a pipeline, and the pipeline passes through the plane six-way valve (13) to the gas chromatograph (12); on the other hand, the water-cooled gas enters the water cooler (3) through a pipeline, the separator (4) enters the compressor (10) through a drying part through a pipeline, the outlet of the compressor (10) is connected with the heat exchanger (2) through a pipeline, and the inter-stage cooler (11) is respectively connected with the inlet pipeline and the outlet pipeline of the compressor (10).

5. The dedicated apparatus according to claim 4, characterized in that: the mixer (1) enters a reactor (5) through a pipeline, the pipeline is provided with a check valve and is connected with a pressure display instrument (PI-1) and a needle valve (SA), the inlet of the reactor (5) is provided with a temperature control display instrument (TIC-1) and a temperature display instrument (TI-1), the outlet of the reactor (5) is divided into two paths, one path enters a heat exchanger (2) through the pipeline, the other path leads to the atmosphere through the pipeline, and the pipeline is provided with a stop valve (V2); on one hand, the heat exchanger (2) enters the mixer (1) through a pipeline, the pipeline is connected with a needle valve (SB), and the needle valve (SA) and the needle valve (SB) are connected in parallel and then are connected to a gas chromatograph (12) through a plane six-way valve (13); the other side of the heat exchanger (2) enters a water cooler (3) through a pipeline, the pipeline is provided with a temperature display instrument (TI-2), the water cooler (3) is communicated with the atmosphere through a separator (4) through the pipeline, the pipeline is provided with a stop valve (V1), the separator (4) enters a compressor (10) through a drying part through the pipeline, the pipeline is provided with a temperature control display instrument (TI-3), the drying part is formed by connecting a dryer IA (6) and a dryer IB (7) in series in parallel with a dryer IIA (8) and a dryer IIB (9) in series, the dryer IA (6), the dryer IB (7), the dryer IIA (8) and the dryer IIB (9) are respectively connected with the temperature control display instruments (TIC-2, TIC-3, TIC-4 and TIC-5), and the inlets of the dryer IA (6) and the dryer IIA (8) are respectively provided with an inlet valve (I-1, a temperature display instrument, II-1) and regeneration waste gas outlet valves (I-2, II-2), outlet valves (II-4, I-4) and regeneration nitrogen inlet valves (I-5, II-5) are respectively arranged at the outlets of a dryer IB (7) and a dryer IIB (9), and a pressure display instrument (PI-2), a check valve and a stop valve (V4) are arranged on a pipeline connecting the drying part and the inlet of the compressor (10); the outlet of the compressor (10) is connected with the heat exchanger (2) through a pipeline, a stop valve (V5) and a mass flow meter (FI-1) are arranged on the pipeline, the intersegmental cooler (11) is respectively connected with the inlet pipeline and the outlet pipeline of the compressor (10), and the pipeline connecting the intersegmental cooler (11) and the outlet of the compressor (10) is provided with a stop valve (3) and a check valve.