CN102962055A - Molybdenum-based low-temperature denitration catalyst and preparation thereof - Google Patents

Abstract

The invention discloses a molybdenum-based low-temperature denitration catalyst and a preparation thereof. The catalyst is characterized in that TiO2 is used as a carrier, the oxides of molybdenum are used as active components, one or more of the oxides of metals V, W, Cu, Ni, Zn and Ce are added as auxiliaries, and the active components in the prepared catalyst occupiy 1-15% of the catalyst. The preparation method of the catalyst comprises the steps of ultrasonic mixing, drying, crushing and roasting. By using ammonia as a reducing agent, the denitration efficiency can be up to 80% when the temperature is 130 DEG C and the temperature of an active window is 150-446 DEG C when the catalyst is up to 99%; and during the preparation, drying and roasting are carried out, then the specific surface area and the stability of the catalyst are improved and the service life of the catalyst is prolonged, so that the catalyst has good industrial application prospect. The catalyst is suitable for the smoke low-temperature denitration catalytic processes.

Description

A kind of molybdenum based low-temperature denitration catalyst and preparation method

Technical field

The invention belongs to catalyst technical field, relate generally to a kind of preparation method of low-temperature denitration catalyst.

Background technology

Along with the Environmental Protection in China policy continue step up, for national discharged nitrous oxides total amount during finishing " 12 " is controlled at respectively 2046.2 ten thousand tons, than 2273.6 ten thousand tons of 10% general objectives that descend respectively in 2010, " the severeest denitration standard on the history " came into effect from January 1st, 2012, China's recent five years denitration technology and application will enter large-scale developing stage, and the SCR gas denitrifying technology will be obtained in the power plant field large-scale application with the performance of its efficient stable.Develop commercial V from 20 century 70 Japan ₂O ₅/ TiO ₂System middle temperature catalyst, catalyst have become core link in the SCR technique.

For avoiding the SO in the flue gas ₂With NH ₃Reaction generates NH ₄HSO ₄(NH ₄) ₂SO ₄The pore structure of blocking catalyst.SCR often is disposed between boiler economizer and the air preheater, still, contains a large amount of SO in the flue gas of this arrangement ₂, K ₂O, CaO and As ₂O ₃Deng, can cause catalyst poisoning, and the flying dust of high concentration can cause obstruction and the wearing and tearing of catalyst, reduce its service life; Because the limitation of space and pipeline, existing boiler is carried out denitration transform that difficulty is very large, expense is high, more moved boiler for many years, do not reserved the space that Benitration reactor is installed, between economizer and air preheater, increased Benitration reactor and almost can't realize.Boiler for middle and small scale, the temperature section of warm denitrating catalyst is between economizer and air preheater in the employing, but before economizer, it is higher to transform difficulty, yet its exhaust gas temperature generally is higher than large-sized boiler, for better temperature environment has been created in the application of low temperature catalyst.

Serviceability temperature can solve above-mentioned unfavorable problem at low temperature catalyst below 200 ℃, low temperature catalyst can be installed in after the deduster, solved high ash and arranged that the catalyst that brings stops up and wearing and tearing, the oxidizing sulfur dioxide rate reduces greatly simultaneously, follow-up without the equipment corrosion problem, can not exert an influence to boiler body.After the deduster denitrating catalyst is installed and is greatly reduced installation difficulty, saved steel construction, the space is arranged more flexible, easy.Research to low temperature catalyst makes some progress, and at present research mainly concentrates on the research of Mn-Ti low temperature catalyst and Cu-Zr catalyst, and stability and the life-span of catalyst are not ideal enough, have affected the suitability for industrialized production of catalyst.

Summary of the invention

The preparation method who the purpose of this invention is to provide a kind of molybdenum based low-temperature denitration catalyst of suitable commercial Application

For achieving the above object, the present invention takes following technical scheme:

A kind of molybdenum based low-temperature denitration catalyst and preparation method is characterized in that catalyst is take molybdenum oxide as active component; With TiO ₂Be carrier; MoO wherein ₃Account for TiO ₂1～10% of weight, the metallic element auxiliary agent accounts for TiO ₂0.5～5% of weight.

Aforesaid MoO ₃, be by one or more preparations in ammonium molybdate, ammonium dimolybdate, ammonium tetramolybdate, ammonium heptamolybdate, the ammonium octamolybdate.

In the oxide that aforesaid metal oxide auxiliary agent is V, W, Cu, Ni, Zn, Ce one or more are respectively by nitrate corresponding to metallic element, nitrite, acetate or ammonium salt preparation.

A kind of preparation method of molybdenum based low-temperature denitration catalyst comprises following processing step, it is characterized in that:

(1) ultrasonic batch mixing: open reactor, open supersonic generator, in the ultrasonic response still, add Mkg (M and TiO ₂Identical in quality) deionized water, be warmed up to 50～90 ℃; Press 10%～20% of M quality and add solid acid, stop 10～20min; Press MoO ₃Account for TiO ₂The mass ratio of the 1-10% of weight adds provides MoO ₃Salt, account for TiO by metal element auxiliary agent ₂The 0.5-5% of weight adds the corresponding salt that metal oxide is provided, and stops 20～30min; The titanium dioxide that adds Mkg stops 60～120min, forms pug.

(2) oven dry: the pug that ultrasonic batch mixing obtains is dried 1～3h under 150～190 ℃ temperature, take out dry good siccative, become graininess through crusher in crushing.

(3) calcining: the pellet type catalyst that oven dry obtains is calcined 1～3h in 250～450 ℃, be divided into through grinding screen and make catalyst.

The preparation method of aforesaid a kind of molybdenum based low-temperature denitration catalyst, the solid acid that its ultrasonic batch mixing adds is one or both in oxalic acid, the citric acid.

The present invention is owing to take above technical scheme, and it has the following advantages:

1, the low temperature catalyst activity of this method preparation is higher, can reach the NOx conversion ratio more than 80% in the time of 130 ℃, and active window temperature wider (reaching the temperature range of 99% conversion ratio at 150～446 ℃).2, use the auxiliary batch mixing of ultrasonic wave during this method Kaolinite Preparation of Catalyst, active component is fully mixed, keep higher decentralization.3, during this method Kaolinite Preparation of Catalyst through oven dry and roasting technique, improved specific area and the stability of catalyst, the service life of having improved catalyst.

The specific embodiment

Embodiment 1

A kind of preparation method of molybdenum based low-temperature denitration catalyst comprises following processing step,

(1) ultrasonic batch mixing: open reactor, open ultrasonic unit, in the ultrasonic response still, add deionized water 40kg, be warmed up to 50 ℃, add dilute sulfuric acid 1.4kg, add ammonium molybdate 3.1kg reaction 20min, add oxalic acid 5.4kg reaction 15min,

-2-

Add ammonium metavanadate 2.5kg reaction 30min, add 38kg reaction 90min, become muddy.

(2) drying and roasting: change mud under 150 ℃ of conditions dry 2h, shift out pulverizing, change calcine by steps in the calcining kiln over to; Sintering cures: 120 rev/mins of tunnel cave rotating speeds, and 250 ℃ of district's temperature, 350 ℃ of two district's temperature, 450 ℃ of three district's temperature, 450 ℃ of four district's temperature through 50-60 minute, through being ground into particle, obtain catalyst.

(3) catalyst activity test condition: build experiment porch, catalyst is put into fixedly tubular type heater platform, pass into simulated flue gas (SO ₂=800ppm, NOx=NH ₃=600ppm, O ₂=10%, N ₂Be Balance Air), air speed ratio=9000h ^-1

Import and export the concentration of NOx with NOx analyzer detecting catalyst.

The denitration efficiency computational methods:

$a_{\mathrm{Nox}}=\frac{C_{\mathrm{in}}-C_{\mathrm{out}}}{C_{\mathrm{in}}}100\%$

α _NOxBe denitration efficiency, C _In, C _OutFor importing and exporting NO in the flue gas _xContent (ppm).

The denitration efficiency that obtains is:

Temperature ℃	100	125	150	175	200	225	250
								α NOx	46.1	74.2	98.7	99.6	99.9	99.7	99.4

Embodiment 2

(1) ultrasonic batch mixing: open reactor, open ultrasonic unit, in the ultrasonic response still, add deionized water 40kg, be warmed up to 50 ℃, add dilute sulfuric acid 1.4kg, add ammonium molybdate 3.1kg reaction 20min, add ammonium oxalate 4.8kg reaction 15min, add copper nitrate 2.5kg reaction 30min, add 38kg reaction 90min, become muddy.

(2) drying and roasting: with mud dry 2h under 150 ℃ of conditions, shift out pulverizing, change calcine by steps in the calcining kiln over to; Sintering cures: 120 rev/mins of tunnel cave rotating speeds, and 250 ℃ of district's temperature, 350 ℃ of two district's temperature, 450 ℃ of three district's temperature, 450 ℃ of four district's temperature, 50-60 minute, be ground into particle through impact grinding, obtain catalyst.

(3) the catalyst activity test condition is with example 1.

The denitration efficiency that obtains is:

Temperature ℃	100	125	150	175	200	225	250
								α NOx	56.1	73.2	94.3	99.2	99.5	99.8	98.9

Embodiment 3

(1) ultrasonic batch mixing: open reactor, open ultrasonic unit, in the ultrasonic response still, add deionized water 40kg, be warmed up to 50 ℃, add dilute sulfuric acid 1.4kg, add ammonium molybdate 3.1kg reaction 20min, add 5.4kg reaction 15min, add ammonium metavanadate 2.5kg copper nitrate 3.1kg reaction 30min, add 38kg reaction 90min, become muddy.

(2) drying and roasting: with mud dry 2h under 150 ℃ of conditions, shift out pulverizing, change calcine by steps in the calcining kiln over to; Sintering cures: 120 rev/mins of tunnel cave rotating speeds, and 250 ℃ of district's temperature, 350 ℃ of two district's temperature, 450 ℃ of three district's temperature, 450 ℃ of four district's temperature, 50-60 minute, be ground into particle through impact grinding, obtain catalyst.

(3) the catalyst activity test condition is identical with scheme 1.

The denitration efficiency that obtains is:

Temperature ℃	100	125	150	175	200	225	250
								α NOx	60.1	78	99.6	99.4	99.2	99.2	99.9

Claims (5)

1. a molybdenum based low-temperature denitration catalyst and preparation method is characterized in that catalyst is take molybdenum oxide as active component; With TiO ₂Be carrier; MoO wherein ₃Account for TiO ₂1～10% of weight, the metallic element auxiliary agent accounts for TiO ₂0.5～5% of weight.

2. a kind of molybdenum based low-temperature denitration catalyst according to claim 1 and preparation method is characterized in that described MoO ₃By one or more preparations in ammonium molybdate, ammonium dimolybdate, ammonium tetramolybdate, ammonium heptamolybdate, the ammonium octamolybdate.

3. a kind of molybdenum based low-temperature denitration catalyst according to claim 1 and preparation method, it is characterized in that, in the oxide that described metal oxide auxiliary agent is V, W, Cu, Ni, Zn, Ce one or more are respectively by nitrate corresponding to metallic element, nitrite, acetate or ammonium salt preparation.

4. a kind of molybdenum based low-temperature denitration catalyst according to claim 1 and preparation method, the technical characterictic of its preparation method is, comprises following processing step:

(1) ultrasonic batch mixing

Open reactor, open supersonic generator, in the ultrasonic response still, add the Mkg deionized water, be warmed up to 50～90 ℃; Press 10%～20% of M quality and add solid acid, stop 10～20min; Account for TiO by molybdenum oxide ₂The percentage of the 1-10% of weight adds ammonia molybdenum salt, accounts for TiO by metal element auxiliary agent ₂The 0.5-5% of weight adds corresponding metal nitrate, stops 20～30min; The titanium dioxide that adds Mkg stops 60～120min, forms pug.

(2) oven dry

The pug that ultrasonic batch mixing is obtained joins in the residual heat drying kiln, dries 1～3h under 150～190 ℃ temperature, takes out dry good catalyst, is ground into particle.

(3) calcining

The pellet type catalyst that oven dry is obtained is in calcining kiln, and calcine by steps 1～3h makes catalyst in 250～450 ℃.

5. a kind of molybdenum based low-temperature denitration catalyst preparation method according to claim 4 is characterized in that, the solid acid that ultrasonic batch mixing adds is one or both in oxalic acid, the citric acid.