CN106423139A - Rare-earth-based SCR denitration catalyst and preparation method thereof - Google Patents

Abstract

The invention relates to a rare-earth-based SCR denitration catalyst and a preparation method thereof, and belongs to the technical field of environmental catalysis. The catalyst is a denitration catalyst which is compounded from CeO2 and TiO2 at the medium and low temperature, the active component of the catalyst is cerium dioxide, the carrier is titanium dioxide, and the assistant is transition metal and rare earth metal oxide; and the structural formula of the catalyst is CeO2-MOx/TiO2, CeO2/Mox-TiO2 or CeMTiOy, wherein M is one or several kinds of compounds selected from Al, Si, Y, Zr, Nb, Mo, Sn, Sb, La, Pr, Nd, Sm and W, x ranges from 1 to 3 and y ranges from 2 to 5. The invention has the advantages that no toxic substance V2O5 is used in the catalyst, the catalyst has good NO(i) x(/i) conversion rate, N2 selectivity and NH3 conversion rate in the range of 200-500 DEG C, the SO2 conversion rate is small, the H2O and alkali metal poisoning prevention capability is superior to that of commercial vanadium-titanium catalysts.

Description

A kind of rare earth base SCR denitration and preparation method

Technical field

The present invention relates to a kind of be applied to nitrogen-containing oxide（NOx）Flue gas and the NO being similarly composedxDusty gass removing Rare earth base catalyst and preparation method, and in particular to a kind of rare earth base SCR denitration and preparation method, belong to environmental catalysis Technical field.

Technical background

NOxIt is not only the significant contributor of acid rain, and forms surface layer ozone pollution, photochemical fog, secondary Subparticle pollution and the front extract of earth's surface eutrophication, the problem for thus causing is become with depletion of the ozone layer, global climate Changing becomes the atmospheric environment hot issue for projecting the most together.

At present SCR method is considered as best denitration technology, it be under special catalyst effect, with ammonia or other reduction Agent is selectively by NOxIt is reduced to N₂Method.Wherein, with NH₃For reducing agent SCR technology because of its efficiency high, non-secondary pollution And be widely applied.In whole SCR technique, catalyst is most crucial part in system.SCR catalyst development is main Experienced three phases, noble metal catalyst, molecular sieve catalyst and metal oxide catalyst.Noble metal catalyst generally with Pt, Rh, Pd etc. are used as active component, and aluminium oxide or monoblock type pottery are used as carrier, and the active temperature of the catalytic reaction is interval relatively Low, generally below 300 °C, but temperature window is narrower, and has by-product N₂O is generated, in addition to NH₃Certain oxidation is had to make With to the SO in flue gas₂Also more sensitive and relatively costly.Metal ion exchanged molecular sieve catalyst mainly include Y type, ZSM series and mordenite etc..The effective active temperature of such catalyst is interval higher, reaches as high as 600 °C, but main use Under conditions of gas emission control equitemperature is higher.Metal oxide catalyst NH under excess oxygen₃Have in-SCR reaction Preferable catalysis activity, the assembling of generation current factory for V₂O₅-WO₃/TiO₂Catalyst, but its active temperature windows is narrower, and institute The V for using is poisonous, can produce serious harm to environment and health, and Ministry of Environmental Protection promulgates《With regard to strengthening the cigarette that gives up The notice of QI prostration denox catalyst supervision》, clearly by waste flue gas denitration catalyst（Vanadium titanium system）Include Hazardous Wastes Management.Cause This, development environment is friendly, the rare earth based denitration catalyst of excellent performance is significant.

Content of the invention

The purpose of the present invention is the problem for existing for existing catalyst, provides a kind of low cost, activity height, preparation method Simply, eco-friendly rare earth base SCR denitration and preparation method.

The catalyst of the present invention is a kind of middle low temperature CeO₂With TiO₂Compound denitrating catalyst, the active component of catalyst For ceria, it is transition metal and rare-earth oxide that carrier is titanium dioxide, auxiliary agent；The catalyst structure formula is CeO₂-MO_x/TiO₂、CeO₂/MO_x-TiO₂Or CeMTiO_y, wherein：M is Al, Si, Y, Zr, Nb, Mo, Sn, Sb, La, Pr, Nd, Sm And one or more in W, the span of x is 2-5 for the span of 1-3, y.

Described CeO₂-MO_x/TiO₂Or CeO₂/MO_x-TiO₂In catalyst, the weight/mass percentage composition of each component is：CeO₂ 1%-20%、MO_x1%-25%, balance of TiO₂.

CeMTiO_yCeO in catalyst₂With TiO₂Mol ratio be 0.05-0.4, MO_xWith TiO₂Mol ratio be 0.05- 0.3.

Described CeO₂-MO_x/TiO₂Catalyst is synthesized using infusion process, and preparation technology comprises the steps：

To 2-40g TiO₂Middle addition 20-400 mL deionized water, mix homogeneously, in proportion accordingly add 0.5-20 g Ce and The saline solution of 0.1-10g M, stirs 1-5 h, supersound process 1-3 h, stands 10-30 h, 80-120 under room temperature^o6- is dry under C 24 h, 500-700^oRoasting 3-8 h under C, heating rate is 3-10^oC/min.

Described CeO₂/MO_x-TiO₂Catalyst is synthesized using infusion process, and preparation technology comprises the steps：

To 2-40g MO_x-TiO₂Middle addition 20-400 mL deionized water, mix homogeneously, accordingly add 0.5-20 g in proportion Ce saline solution, stirs 1-5 h, supersound process 1-3 h, stands 10-30 h, 80-120 under room temperature^o6-24 h, 500- is dry under C 700^oRoasting 3-8 h under C, heating rate is 3-10^oC/min.

Described CeMTiO_yCatalyst adopts Co deposited synthesis, and preparation technology comprises the steps：

2-20 g Ce salt, 10-40 g Ti (SO are stoichiometrically weighed₄)₂With slaine of the 0.1-10g containing M, 20- is dissolved in In 400 mL deionized waters, one or two precipitant are added dropwise in above-mentioned solution to pH=8-12, the precipitation for obtaining is through old Change, washing, filter after, 80-120^o6-24 h, 400-700 is dry under C^oRoasting 3-8 h under C, heating rate is 3-10^oC/ min.

The precipitant is：NH₃∙H₂O、(NH₄)₂CO₃、NH₄HCO₃, NaOH or NaHCO₃.

Heretofore described catalyst is mainly used for flue gas SCR denitration field, and concrete reaction condition is as follows：Simulation cigarette Gas gas volume ratio is consisted of：100-1500 ppm NO, 100-1500 ppm NH₃, 3-8% O₂, 0-20% H₂O, 0-2000 ppm SO₂, Ar is carrier gas, air speed（GHSV）For 3 000-120,000 h^-1.NH₃/ NO volume ratio is 0.5-1.5, and alkali metal adds 1-10% of the dosage in mass ratio for catalyst amount, gas detecting system is the Fourier transform infrared analysis for being furnished with gas cell Instrument.

Using technique scheme, the technique effect of the present invention has：

1. the preparation method of the present invention is simple, easily realizes industrialized production, and obtained catalyst Modulatory character compares By force, by regulation activity component CeO₂Content, the doping of third component M, precipitant species, precipitation pH value etc. can improve The denitration performance of catalyst.

2. the catalyst operation temperature window width involved by the present invention, with good stability and anti-H₂O、SO₂With Alkali metal performance.Particularly, Ce_0.2W_0.1TiO_yCatalyst is in 250-450^oIn the range of C, NO removal efficiency is up to 100%, N₂Choosing Selecting property is more than 95%, SO₂Conversion ratio is less than 1%, and alkali resistant metal poisoning ability is better than commercial vanadium Titanium series catalyst；Particularly, 5% CeO₂/5%WO₃-TiO₂（Mass ratio）Catalyst 200-450^oIn the range of C, NO removal efficiency is up to 100%, N₂Selectivity is more than 93%, SO₂Conversion ratio is less than 1%, and alkali resistant metal poisoning ability is better than commercial vanadium Titanium series catalyst；Particularly, 10%CeO₂-10% WO₃/TiO₂（Mass ratio）Catalyst is in 250-500^oIn the range of C, NO removal efficiency is up to 100%, N₂Selectivity is more than 95%, SO₂ Conversion ratio is less than 1%, and alkali resistant metal poisoning ability is better than commercial vanadium Titanium series catalyst.

The active component of the present invention is mainly rare earth element ce, eliminates the use of toxic element V, environmentally friendly.Should Product is widely portable to moving source and the stationary source denitration fields such as vehicle exhaust, thermal power plant, glass factory and chemical plant.

Description of the drawings

Fig. 1 is Ce_0.2W_0.1TiO_yThe anti-H of catalyst₂O and SO₂Poisoning performance test result figure（Surveyed with transformation efficiency of the oxides of nitrogen Test result is weighed）.

Fig. 2 is Na to Ce_0.2W_0.1TiO_yAnd V₂O₅-WO₃/TiO₂(VWTi) catalyst performance impact figure（Turned with nitrogen oxides Rate test result is weighed）.

Fig. 3 is K to Ce_0.2W_0.1TiO_yAnd VWTi catalyst performance impact figure（Weighed with transformation efficiency of the oxides of nitrogen test result Amount）.

Specific embodiment

Embodiment 1：

5%CeO is synthesized using infusion process₂/5%WO₃-TiO₂（Mass ratio）Catalyst is used for flue gas SCR denitration, specific implementation step As follows：

Weigh 0.974g Ce (CH₃COO)₃·H₂O adds 100 mL deionized waters and 10 g 5%WO in 200 mL beakers₂- TiO₂, 1 h of supersound process, 6 h of magnetic agitation, 110^oIt is dried overnight under C, 500^o4 h of roasting under C（Heating rate is 5^oC/ min）Required 5%CeO is obtained₂/5% WO₃-TiO₂Catalyst.

SCR denitration performance test is used for using the catalyst of said method synthesis：Will be anti-as fixed bed for 0.4 g catalyst Answer in device, reacting gas is consisted of（Volume ratio）500 ppm NO, 500 ppm NH₃, 5% O₂, Ar is carrier gas, air speed（GHSV） For 20 000 h^-1.Gas detecting system is the Fourier transform infrared analyser for being furnished with gas cell.

5%CeO₂/5% WO₃-TiO₂Catalyst denitration performance test result is as follows：

Embodiment 2：

10%CeO is synthesized using infusion process₂-10%WO₃/TiO₂（Mass ratio）Catalyst is used for flue gas SCR denitration, is embodied as step Rapid as follows：

Weigh 1.261 g Ce (NO₃)₃·6H₂O、0.518 g (NH₄)₆W₇O₂₄·6H₂O adds 50 mL in 100 mL beakers Deionized water and 4 g carrier TiO₂, 1 h of supersound process, 1 h of magnetic agitation, 110^oIt is dried overnight under C, 500^o4 h of roasting under C （Heating rate is 5^oC/min）Required 10%CeO is obtained₂-10%WO₃/TiO₂Catalyst.

SCR denitration performance test is used for using the catalyst of said method synthesis, test condition is with embodiment 1.

10%CeO₂-10%WO₃/TiO₂Catalyst denitration performance test result is as follows：

Embodiment 3：

Using Co deposited synthesis Ce_0.2Mo_0.1TiO_y（Mol ratio）Catalyst is used for flue gas SCR denitration, and specific implementation step is such as Under：

Weigh 3.799 g Ce (NO₃)₃·6H₂O、0.772 g (NH₃)₆Mo₇O₂₄·4H₂O and 10.5 g Ti (SO₄)₂In 250 In mL deionized water, Deca NH after stirring₃·H₂O to pH=10, sucking filtration, washing after room temperature 4 h of ageing, 110^oDry under C Overnight, 500^o5 h of roasting under C（Heating rate is 5^oC/min）Required Ce is obtained_0.2Mo_0.1TiO_yCatalyst.

Tested for denitration performance using the catalyst of said method synthesis, test condition is with embodiment 1.

Ce_0.2Mo_0.1TiO_yCatalyst denitration performance test result is as follows：

Embodiment 4：

Using Co deposited synthesis Ce_0.2W_0.1TiO_y（Mol ratio）Catalyst is used for coal-fired flue gas denitration, and specific implementation step is such as Under：

Weigh 3.799 g Ce (NO₃)₃·6H₂O、10.5 g Ti(SO₄)₂With 1.18 g (NH₄)₆W₇O₂₄·6H₂O is in 250 mL In deionized water, Deca NH after stirring₃·H₂O to pH=10, sucking filtration, washing after room temperature 4 h of ageing, 110^oDry under C Overnight, 500^o5 h of roasting under C（Heating rate is 5^oC/min）Required Ce is obtained_0.2W_0.1TiO_yCatalyst.

SCR denitration performance test is used for using the catalyst of said method synthesis, test condition is with embodiment 1.

Ce_0.2W_0.1TiO_yCatalyst denitration performance test result is as follows：

Investigate Ce_0.2W_0.1TiO_yThe anti-H of catalyst₂O and SO₂Poisoning performance, reacting gas is consisted of（Volume ratio）500 ppm NO, 500 ppm NH₃, 500 ppm SO₂, 5% O₂, 10%H₂O, Ar are carrier gas, air speed（GHSV）For 20 000 h^-1, catalyst amount For 0.4 g.

Ce_0.2W_0.1TiO_yCatalyst is 370^oAnti- H under C₂O and SO₂Poisoning performance test result is shown in accompanying drawing 1.

Investigate Ce_0.2W_0.1TiO_yCatalyst alkali resistant metal poisoning performance, and with traditional V₂O₅-WO₃/TiO₂(VWTi) it is catalyzed The antitoxin performance of agent is contrasted, and reacting gas is consisted of（Volume ratio）500 ppm NO, 500 ppm NH₃, 5% O₂, Ar is for carrying Gas, air speed（GHSV）For 20 000 h^-1, catalyst amount is 1-3% of 0.4 g, the alkali metal consumption for catalyst quality（Quality Than）.

Ce_0.2W_0.1TiO_yCatalyst alkali resistant metal poisoning ability and its accompanying drawing 2, attached is seen with VWTi performance comparison test result Fig. 3.

Knowable to above-mentioned test result, Ce_0.2W_0.1TiO_y、10%CeO₂-10%WO₃/TiO₂And 5%CeO₂/5%WO₃-TiO₂Urge Agent can efficiently remove the NO in flue gas_x, N₂Selectivity and NH₃High conversion rate, and with superior anti-H₂O、SO₂And alkali gold Category poisoning capability, meets the requirement of low emission, therefore can apply to actual flue gas SCR denitration field.

Claims (7)

1. a kind of rare earth base SCR denitration, is characterized in that：The active component of the catalyst is ceria, and carrier is Titanium dioxide, auxiliary agent is transition metal and rare-earth oxide；The catalyst structure formula is CeO₂-MO_x/TiO₂、CeO₂/ MO_x-TiO₂Or CeMTiO_y, wherein：M is one or more in Al, Si, Y, Zr, Nb, Mo, Sn, Sb, La, Pr, Nd, Sm and W, The span of x is 2-5 for the span of 1-3, y.

2. rare earth base SCR denitration according to claim 1, is characterized in that： CeO₂-MO_x/TiO₂Or CeO₂/MO_x- TiO₂In catalyst, the weight/mass percentage composition of each component is：CeO₂1%-20%、MO_x1%-25%, balance of TiO₂.

3. rare earth base SCR denitration according to claim 1, is characterized in that： CeMTiO_yCeO in catalyst₂With TiO₂Mol ratio be 0.05-0.4, MO_xWith TiO₂Mol ratio be 0.05-0.3.

4. a kind of CeO according to claim 1₂-MO_x/TiO₂The preparation method of catalyst, is characterized in that：Using infusion process Synthesis, preparation technology comprises the steps：

To 2-40g TiO₂Middle addition 20-400 mL deionized water, mix homogeneously, in proportion accordingly add 0.5-20 g Ce and The saline solution of 0.1-10g M, stirs 1-5 h, supersound process 1-3 h, stands 10-30 h, 80-120 under room temperature^o6- is dry under C 24 h, 500-700^oRoasting 3-8 h under C, heating rate is 3-10^oC/min.

5. a kind of CeO according to claim 1₂/MO_x-TiO₂The preparation method of catalyst, is characterized in that：Using infusion process Synthesis, preparation technology comprises the steps：

To 2-40g MO_x-TiO₂Middle addition 20-400 mL deionized water, mix homogeneously, accordingly add 0.5-20 g Ce in proportion Saline solution, stirs 1-5 h, supersound process 1-3 h, stands 10-30 h, 80-120 under room temperature^o6-24 h, 500- is dry under C 700^oRoasting 3-8 h under C, heating rate is 3-10^oC/min.

6. a kind of CeMTiO according to claim 1_yThe preparation method of catalyst, is characterized in that：Closed using coprecipitation Become, preparation technology comprises the steps：

2-20 g Ce salt, 10-40 g Ti (SO are stoichiometrically weighed₄)₂With slaine of the 0.1-10g containing M, 20- is dissolved in In 400 mL deionized waters, one or two precipitant are added dropwise in above-mentioned solution to pH=8-12, the precipitation for obtaining is through old Change, washing, filter after, 80-120^o6-24 h, 400-700 is dry under C^oRoasting 3-8 h under C, heating rate is 3-10^oC/ min.

7. CeMTiO according to claim 6_yThe preparation method of catalyst, is characterized in that：The precipitant is：NH₃∙ H₂O、(NH₄)₂CO₃、NH₄HCO₃, NaOH or NaHCO₃.