CN103230803B - Copper-based cerium-cobalt-lanthanum composite oxide catalyst and preparation method thereof - Google Patents
Copper-based cerium-cobalt-lanthanum composite oxide catalyst and preparation method thereof Download PDFInfo
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Abstract
The invention discloses a catalyst for selective reduction of NO by propylene and a preparation method thereof. The catalyst is low in optimal catalytic activity temperature and has high catalytic activity in a wide temperature range. The preparation method comprises the following steps: regulating the pH value of a (NH4)2CO3 or NH4HCO3 solution to 8-12 with ammonia water, heating, and slowly and dropwisely adding a mixed salt solution of cerium salt, cobalt salt and lanthanum salt while stirring; drying the generated solid, and roasting to obtain a Ce-Co-La-O composite oxide supporter; and impregnating the obtained Ce-Co-La-O composite oxide supporter in a copper salt water solution, and roasting to obtain the Cu/Ce-Co-La-O oxide.
Description
Technical field
The present invention relates to catalyst, specifically adopt copper base cerium cobalt lanthanium complex oxide catalyst and the manufacture method thereof of the NOx in propylene purified treatment burnt gas.
Background technology
Along with the high speed development of the coal-fired industries such as thermal power generation and the quick growth of an oil-fired vehicle recoverable amount, the nitrogen oxide discharged in atmospheric environment (NOx) increases day by day.NOx is more and more serious on the impact of ecological environment, not only pollutes, destroys natural environment, and directly cause the diseases such as the decline of human body myocardial contractive power, respiratory and circulatory failure, threatens human health.Therefore, NO
xthe control of polluting and control cause global showing great attention to.NO
xamong NO account for more than 90%, how effectively eliminate vital task and the study hotspot that NO just becomes current field of Environment Protection.
Early 1990s, Iwamoto etc. report Cu-ZSM-5 can play catalytic action under excess oxygen result of study to hydrocarbon compound selective reduction NO, showing Selective Catalytic Reduction of NO is eliminate the effective ways of NO, causes the broad interest of countries in the world scientific worker.Adopt NH
3for the Selective Catalytic Reduction of NO technology of reducing agent, can be applied in enterprises such as coal-fired power plants at present, and the application in fuel engines exhaust emissions purification etc., remain at NH
3there is stronger corrosivity and be difficult to the problems such as control.The technology being the Selective Catalytic Reduction of NO of reducing agent due to employing hydro carbons has range of application widely, so be subject to the attention of countries in the world scientific worker always.
Adopting hydro carbons to be in the research of reducing agent Selective Catalytic Reduction of NO, be that the research of reducing agent is more extensive with propylene.Report the achievement in research about Propylene Selectivity Reduction of NO in recent years successively.The result of study of document shows, in the research of Propylene Selectivity reductive NO, the main catalyst adopted has molecular sieve catalyst, noble metal catalyst, metal oxide catalyst and post layer clay catalyst.Wherein, noble metal catalyst, because price is high and reserves are limited, is thus difficult to large-scale application and development; Activity of molecular sieve catalysts is better, but hydrothermal stability is not good enough, in the presence of water vapor easy inactivation; The hydrothermal stability of post layer clay catalyst is better than molecular sieve catalyst, but the miscellaneous and interlayer post of preparation process easily caves in; Metal oxide catalyst is extensively favored because of its good hydrothermal stability always, but catalytic activity must be improved and reduce best catalytic activity temperature, current common demands best catalytic activity temperature higher than 300 DEG C, and can not have higher catalytic activity in wider temperature range.
It take hydroxyl-aluminium cross-linked montmorillonite as catalyst and the preparation method of the propylene in oxygen-rich condition selective reduction NO of carrier that CN1623634A discloses a kind of.Its catalyst comprises carrier aluminum cross-linked montmorillonite, by adopting SO
4 2-modification is carried out to carrier, under air or inert atmosphere, pricise pretreatment is carried out to carrier aluminum cross-linked montmorillonite, then use Cu
2+solution impregnation, drying and roasting form, and the conversion ratio of NO can be made to reach about 50%.
CN1706547A is open a kind of with γ-Al
2o
3for catalyst and the preparation method of the propylene in oxygen-rich condition selective reduction NO of carrier, first use SO
4 2-to carrier γ-Al
2o
3carry out modification, then use La
3+solution impregnation, after dry and roasting, then uses Cu
2+solution impregnation, drying and roasting form, and at 300 DEG C, catalyst can reach more than 83% to the conversion ratio of NO, but NO conversion ratio is very low at low temperatures and high temperatures.
CN1762591A discloses the catalyst of a kind of propylene in oxygen-rich condition selective reduction NO, and complex carrier active component is La
2o
3-ZrO
2-Al
2o
3, use Cu
2+solution impregnation, drying and roasting form.The present invention can make the conversion ratio of NO up to more than 84%, but NO conversion ratio is not high yet at low temperatures and high temperatures.
CN101015808A is open a kind of with γ-Al
2o
3for the Catalysts and its preparation method of the propylene in oxygen-rich condition selective reduction NO of carrier.By NH
4al (SO
4)
2solution instillation NH
4hCO
3and NH
3h
2the mixed solution of O is to prepare γ-Al
2o
3presoma, obtains γ-Al after ageing, suction filtration, drying, roasting
2o
3carrier, with Cu (NO
3)
2solution impregnation, drying and roasting form, and the optimum activity temperature of catalyst is 275 DEG C, but NO conversion ratio is not high yet at low temperatures and high temperatures.
CN101176845A discloses the catalyst of a kind of propylene in oxygen-rich condition selective reduction NO, and complex carrier active component is CeO
2-Al
2o
3, complex carrier Co deposited synthesis, then adopts La
3+solution impregnation, dry, roasting, then use Cu
2+solution impregnation, drying and roasting form, and the optimum activity temperature of catalyst is 300 DEG C, but activity is not high at low temperatures and high temperatures.
CN101422734A discloses a kind of under excess oxygen, adopt propylene purified treatment NO Cu-series catalyst and manufacture method thereof, is heated by ammonium carbonate solution, instills Al (NO under stirring
3)
3, La (NO
3)
2and/or ZrOCl
2aqueous solution composition, drying roasting obtains complex carrier, then uses Cu
2+solution impregnation, dry, roasting obtains catalyst, and the optimum activity temperature of catalyst is 300 DEG C, but under low temperature and high temperature, activity is not high yet.
CN102698765A discloses a kind of composite denitration Catalysts and its preparation method of selecting reduction of NO by propylene, carrier is ceramic honey comb, molecular sieve, silica-gel carrier, activated carbon fiber, diatomite, ceramic wafer or metal alloy, catalytic active component is copper cobalt and cerium compound oxide, the optimum activity temperature of catalyst is 220 DEG C, but under high temperature, activity is lower.
Summary of the invention
The object of the present invention is to provide a kind of best catalytic activity temperature for lower, and there is in wider temperature range the copper base cerium cobalt lanthanium complex oxide Catalysts and its preparation method of the employing selecting reduction of NO by propylene of higher catalytic activity.
The preparation method of catalyst of the present invention comprises the following steps:
A. compound concentration is the (NH of 1-2mol/L
4)
2cO
3or NH
4hCO
3the aqueous solution, regulates its pH=8-12 with the ammoniacal liquor of mass concentration 20-35%;
B. water-soluble cerium salt, water soluble cobaltous salt and water soluble lanthanum salt are pressed Ce
3+, Co
2+, La
3+the ratio of mol ratio 1 ︰ 0.06-0.2 ︰ 0-0.1 adds water and is mixed with the mixing salt solution of metal ion total concentration 0.2-0.3mol/L;
C. by (NH
4)
2cO
3or NH
4hCO
3solution is heated to 30-40 DEG C, under stirring, by (NH
4)
2cO
3or NH
4hCO
3the ratio of metal ion summation 3 ︰ 1-2 in molal quantity and mixing salt solution, slow instillation mixing salt solution, ageing suction filtration after 4-16 hours after instillation completely, the solids that reaction generates is in 500-750 DEG C of roastings after 100-150 DEG C of dryings, and after cooling, grinding obtains Ce-Co-La-O composite oxide carrier;
After the copper salt solution of D.Ce-Co-La-O composite oxide carrier dipping 0.01-0.1 mol/L, in 100-150 DEG C of dryings, in 450-650 DEG C of roastings after grinding, obtain Cu/Ce-Co-La-O catalyst.
In steps A, preferred pH=9-11 of the mixed solution be made into.
In step B, the preferred cerous nitrate of water-soluble cerium salt, cerous sulfate or cerium chloride, water soluble cobaltous salt is cobalt nitrate, cobaltous sulfate or cobalt chloride, and water soluble lanthanum salt is lanthanum nitrate, lanthanum sulfate or lanthanum chloride.
In step B, Ce
3+, Co
2+, La
3+mol ratio be preferably 0.8-1 ︰ 0.09-0.11 ︰ 0.05-0.07.
In step C, after the solids that reaction generates carries out described drying, then impregnating effect concentration is the aqueous hydrogen peroxide solution of 2-20%, then carries out described roasting.
In step D, mantoquita is preferably copper nitrate, copper sulphate or copper chloride, and the concentration of mantoquita is 0.04-0.06 mol/L.
The present invention adopts back titration coprecipitation method to prepare Cu/Ce-Co-O or Cu/Ce-Co-La-O catalyst, to C
3h
6selective reduction NO has good catalytic performance, the NO conversion ratio 200 DEG C time of Cu/Ce-Co-La-O catalyst is wherein 49.0%, 250 DEG C for best catalytic activity temperature, NO conversion ratio be 81.6%, when 600 DEG C, NO conversion ratio also reaches 52.5%, there is low-temperature catalytic activity and effectively improve heat endurance, catalytic activity wider range, possesses actual application prospect.
Accompanying drawing explanation
Fig. 1 is C on catalyst of the present invention
3h
6the relation curve of the NO conversion ratio that selective reduction NO reacts and temperature.
Fig. 2 is the influence curve of steam to Cu/Ce-Co-La-O catalytic activity.
Fig. 3 is the XRD spectra of catalyst.
Fig. 4 is the H of catalyst
2-TPR composes.
Fig. 5 is the infrared spectrogram of catalyst 150 DEG C of pyridine adsorption.
Fig. 6 is the infrared spectrogram of catalyst 300 DEG C of pyridine adsorption.
Fig. 7 is the thermogravimetric curve of catalyst.
Fig. 8 is the SEM photo of Cu/Ce-Co-O catalyst.
Fig. 9 is the SEM photo of Cu/Ce-Co-La-O catalyst.
Detailed description of the invention
Embodiment 1
Be (the NH of 1.5mol/L in 500ml concentration
4)
2cO
3add the ammoniacal liquor of 25wt% in the aqueous solution, be made into the mixed solution of pH=10.With Ce
3+︰ Co
2+the ratio of mol ratio 0.9 ︰ 0.1, takes the Ce (NO of respective amount
3)
36H
2o and Co (NO
3)
26H
2o, adds deionized water, is slowly stirred to and dissolves completely, be mixed with Ce
3+and Co
2+concentration summation is the mixing salt solution 2000ml of 0.25mol/L, introduces in separatory funnel.
By ammoniacal liquor and (NH
4)
2cO
3the mixed solution of solution is placed in heat collecting type magnetic force thermostatic mixer constant temperature 35 DEG C and stirs continuously, slowly instills Ce (NO
3)
36H
2o and Co (NO
3)
26H
2in the mixed solution of O, continue after instillation to stir 1h completely.Reaction product carries out suction filtration after room temperature ageing 8h, Constant Temp. Oven is put in 120 DEG C of freeze-day with constant temperature 12h after filter cake being left standstill 2h, with 5wt% aqueous hydrogen peroxide solution dipping, sealing and standing 2h after grinding, put into Muffle furnace after suction filtration in 650 DEG C of roasting 3h.After cooling, grinding obtains Ce-Co-O composite oxide carrier again.
Cu (the NO of Ce-Co-O carrier and 0.05 mol/L
3)
2solution incipient impregnation 24h, then 110 DEG C of freeze-day with constant temperature 12h in baking oven, put into Muffle furnace in 550 DEG C of constant temperature calcining 2h after grinding.Then grind screening, obtain the catalyst based Cu/Ce-Co-O of Cu.
Embodiment 2
Be (the NH of 1.5mol/L in 500ml concentration
4)
2cO
3add the ammoniacal liquor of 25wt% in the aqueous solution, be made into the mixed solution of pH=10.With Ce
3+︰ Co
2+︰ La
3+the ratio of mol ratio 0.9 ︰ 0.1 ︰ 0.06, takes the Ce (NO of respective amount
3)
36H
2o, Co (NO
3)
26H
2o and La (NO
3)
36H
2o, adds deionized water, is slowly stirred to and dissolves completely, be mixed with Ce
3+, Co
2+and La
3+concentration summation is the solution 2000ml of 0.25mol/L, introduces in separatory funnel.
By ammoniacal liquor and (NH
4)
2cO
3the mixed solution of solution is placed in heat collecting type magnetic force thermostatic mixer constant temperature 35 DEG C and stirs continuously, slowly instills Ce (NO
3)
36H
2o, Co (NO
3)
26H
2o and La (NO
3)
36H
2in the mixed solution of O, continue after instillation to stir 1h completely.Reaction product carries out suction filtration after room temperature ageing 8h, Constant Temp. Oven is put in 120 DEG C of freeze-day with constant temperature 12h after filter cake being left standstill 2h, with 5wt% aqueous hydrogen peroxide solution dipping, sealing and standing 2h after grinding, put into Muffle furnace after suction filtration in 650 DEG C of roasting 3h.After cooling, grinding obtains Ce-Co-La-O composite oxide carrier again.
Cu (the NO of Ce-Co-La-O carrier and 0.05 mol/L
3)
2solution incipient impregnation 24h, then 110 DEG C of freeze-day with constant temperature 12h in baking oven, put into Muffle furnace in 550 DEG C of constant temperature calcining 2h after grinding.Then grind screening, obtain the catalyst based Cu/Ce-Co-La-O of Cu.
The catalyst obtained to above-mentioned 2 embodiments carries out following active testing
Carry out in miniature fixed-bed quartz reactor device (diameter is 8mm).Reactor feed gas consists of: Ф (NO)=0.20%, Ф (C
3h
6)=0.12%, Ф (O
2)=2.0%, balances with He gas.Catalyst amount is 0.500g; Reacting gas air speed is 20000h
-1.Reacting gas composition vertical 9790 gas chromatographs of good fortune detect, six-way valve sample introduction.Carrier gas is He, and packed column is Porapak N and 5A molecular sieve, and column temperature is 120 DEG C.Thermal Conductivity, bridge electric current is 155mA.With the content of each component of FGA-4100 five component automobile exhaust analyzer on-line checkingi gaseous mixture, with N
2generation calculate NO conversion ratio.Investigate steam when affecting catalyst activity, reaction gas brings the steam of 10% (Ф) into by double plunger micro pump and heating furnace, and adjust He flow maintain total tolerance and other reactive component concentration constant.
Fig. 1 is C on Cu/Ce-Co-O and Cu/Ce-Co-La-O catalyst
3h
6the relation of the NO conversion ratio that selective reduction NO reacts and temperature, evaluates the performance of each catalyst with the conversion ratio of NO.In figure, b is the curve of Cu/Ce-Co-O catalyst, and c is the curve of Cu/Ce-Co-La-O catalyst.Fig. 1 is known, and when on Cu/Ce-Co-O catalyst, when 200 DEG C, NO conversion ratio is 34.6%, 270 DEG C is best catalytic activity temperature, NO conversion ratio is 74.2%, 600 DEG C, NO conversion ratio is 34.4%; When on Cu/Ce-Co-La-O catalyst, when 200 DEG C, NO conversion ratio is 49.0%, 250 DEG C is best catalytic activity temperature, NO conversion ratio is 81.6%, 600 DEG C, NO conversion ratio also reaches 52.5%.
When Fig. 2 is Cu/Ce-Co-La-O catalyst at anhydrous steam with containing 10% (Ф) steam, the measurement result of catalytic performance.In figure, the conversion ratio of NO when curve a is anhydrous steam, curve b is the conversion ratio containing NO during 10% (Ф) steam, and Fig. 2 is known, and when steam exists, best catalytic activity temperature is 260 DEG C, and NO maximum conversion rate is 80.1%.That is to say, compared with during anhydrous steam, when steam exists, best catalytic activity temperature is rising 10 DEG C, and NO maximum conversion rate is decline 1.5%.This shows, Cu/Ce-Co-La-O catalyst has good vapour resistant performance.
The catalyst obtained to above-mentioned 2 embodiments carries out X-ray diffraction (XRD) test
X-ray diffraction (XRD) test is carried out on German Bruker-D8 type X-ray diffractometer, adopts Cu
k α radiation source, tube current 40mA, tube voltage 40kV.
Fig. 3 is the XRD spectra of Cu/Ce-Co-O and Cu/Ce-Co-La-O catalyst, and 2 kinds of catalyst all only demonstrate face-centered cubic fluorite type structure CeO
2characteristic diffraction peak.In figure, b is the XRD spectra of Cu/Ce-Co-O catalyst; C is the XRD spectra of Cu/Ce-Co-La-O catalyst.
The CeO of Cu/Ce-Co-O catalyst
2characteristic diffraction peak lays respectively at 28.62 ° (111), 33.02 ° (200), 47.61 ° (220), 56.52 ° (311), 69.46 ° (400) and 76.92 ° (331), does not occur the diffraction maximum of Co species.Co ion (the ionic radius Co compared with small ionic radii can be thised is presumably because
2+for 0.074nm, Co
3+be 0.063 nm) partly instead of larger Ce ion (the ionic radius Ce of ionic radius
4+be 0.097 nm, Ce
3+be 0.114 nm), thus infilter CeO
2lattice in, form Ce-Co-O solid solution.This is conducive to Co and Ce and good synergy occurs, can impel the activity of catalyst improve and best catalytic activity temperature obviously reduce.
The CeO of Cu/Ce-Co-La-O catalyst
2characteristic diffraction peak lays respectively at 28.50 ° (111), 32.86 ° (200), 47.36 ° (220), 56.24 ° (311), 69.18 ° (400) and 76.61 ° (331), does not occur the diffraction maximum of Co species and La species.The La that ionic radius is larger can be thised is presumably because
3+(ionic radius is 0.115 nm) Some substitute Ce
4+(ionic radius is 0.097 nm) infilters CeO
2lattice in, form Ce-Co-La-O solid solution, so contribute to improving catalytic activity further.Simultaneously due to La
3+enter CeO
2lattice, is conducive to the heat endurance improving carrier, impels catalyst at high temperature still can keep higher catalytic activity.
Adopt traditional coprecipitation, infusion process etc. all can not obtain Ce-Co-O solid solution.And above-mentioned situation shows, the present invention adopts the coprecipitation method of improvement can obtain Ce-Co-O solid solution and Ce-Co-La-O solid solution.Due to obtaining of solid solution carrier, can promote that between Ce, Co, La, better performance acts synergistically mutually, to active component Cu, good carrier effect can occur again, this is the key of acquisition superperformance Cu/Ce-Co-La-O catalyst.
In addition, according to Fig. 3 and document, adopt area of computer aided with major diffraction crystal face (111), according to size of microcrystal and the lattice parameter of Debye-Scherrer formulae discovery catalyst, the results are shown in following table:
As seen from table, the size of microcrystal of each catalyst is at 10.21 ~ 9.52nm, and show to adopt the coprecipitation method improved to obtain nanometer-size die, this will be conducive to improving catalytic activity.
The catalyst obtained to above-mentioned 2 embodiments carries out H
2-TPR test analysis
Temperature programmed reduction (H
2-TPR) test carry out on the TPR-chromatogram arrangement of self-chambering, catalyst amount 50 mg, experiment procatalyst prior to 500 DEG C at O
2/ He (20mL/min, 25%O
2) process 30min in air-flow to purify its surface, be down to after room temperature until temperature and switch to H
2/ Ar (20mL/min, 5%H
2) gaseous mixture, after baseline is steady, carry out temperature programmed reduction reaction with the speed of 10 DEG C/min.
From Fig. 3 also, all there is not the diffraction maximum of Cu species in Cu/Ce-Co-O and Cu/Ce-Co-La-O catalyst, this shows that active component Cu is highly dispersed at carrier surface.Fig. 4 is the H of Cu/Ce-Co-O and Cu/Ce-Co-La-O catalyst
2-TPR test result, in figure, b is the reduction peak of Cu/Ce-Co-O catalyst; C is the reduction peak of Cu/Ce-Co-La-O catalyst, and 2 kinds of catalyst all demonstrate two reduction peak.
The peak temperature of Cu/Ce-Co-O catalyst two reduction peak is 494 DEG C and 216 DEG C respectively, wherein peak temperature is the reduction peak that 494 DEG C of persons should be attributed to support C e-Co-O, and peak temperature is the active component Cu species reduction peak that 216 DEG C of persons should be attributed to support C e-Co-O high degree of dispersion on the surface.That is to say, add Co and carrier and active component Cu species reduction peak temperature can be made to reduce by 68 DEG C and 115 DEG C respectively.This is that Co ion infilters CeO owing to defining Ce-Co-O solid solution
2lattice and Lattice Oxygen vacancy concentration is increased, facilitates diffusion and the migration of oxygen, reduces Ce
4+the temperature that ion is reduced, Ce-Co-O solid solution carrier can produce synergy to active component Cu species simultaneously, contributes to the reduction of CuO, thus effectively reduces the best catalytic activity temperature of catalyst.
The peak temperature of Cu/Ce-Co-La-O catalyst two reduction peak is 477 DEG C and 205 DEG C respectively, wherein peak temperature is the reduction peak that 477 DEG C of persons should be attributed to support C e-Co-La-O, and peak temperature is the active component Cu species reduction peak that 205 DEG C of persons should be attributed to support C e-Co-La-O high degree of dispersion on the surface.That is to say, add La and the reduction peak temperature of carrier and active component Cu species can be made further to reduce by 17 DEG C and 11 DEG C respectively.This is due to La
3+infilter CeO
2lattice, further increases Ce
4+low-temperature reduction ability, promote that Ce-Co-La-O carrier and active component Cu species act synergistically, the reduction-oxidation cycle efficieny of Cu species is improved further, and therefore, Cu/Ce-Co-La-O catalyst has better low-temperature catalyzed performance simultaneously.
The catalyst obtained to above-mentioned 2 embodiments carries out Py-IR test analysis
Pyridine adsorption IR spectra (Py-IR) test is carried out on the Spectrum 2000 FT-IR spectrometer of PE company of the U.S., first in oxygen, 500 DEG C are warming up to before Catalyst Adsorption pyridine, and constant temperature process 1 h, be cooled to uniform temperature after vacuumizing and take the photograph catalyst background spectra.Wait to be cooled to 100 DEG C, vacuumize after Adsorption of Pyridine 15 min, then at the temperature of 150,300 DEG C, take the photograph spectrum respectively.
The Py-IR test result of Cu/Ce-Co-O and Cu/Ce-Co-La-O catalyst when Fig. 5 and Fig. 6 is respectively 150 DEG C and 300 DEG C, the Pyridine adsorption IR spectra figure of b to be the Pyridine adsorption IR spectra figure of Cu/Ce-Co-O catalyst, c be Cu/Ce-Co-La-O catalyst in figure.According to the literature, PyL and the PyH+ species that catalyst surface Lewis acid (being abbreviated as L acid) center and Br nsted acid (being abbreviated as B acid) center and Pyridine Molecules (Py) are formed are respectively at 1440 ~ 1460 cm
-1with 1535 ~ 1550 cm
-1produce characteristic absorption peak.Document is pointed out again, 1450 and 1612 cm
-1near assignments in the characteristic peak of Lewis acid, 1540 and 1635cm
-1neighbouring assignments is in the characteristic peak of Br nsted acid.
As shown in Figure 5, the L acid of each catalyst is different with B acid acid amount: L acid and B acid appear in Cu/Ce-Co-O catalyst; Cu/Ce-Co-La-O catalyst L acid reduces and B acid increases.This shows that Co and Ce forms Ce-Co-O solid solution, effectively can increase B acid acid amount; Add La and Ce, Co and form Ce-Co-La-O solid solution, B acid acid amount can be increased further.
Comparison diagram 5 and Fig. 6 can see again, and pyridine adsorption temperature is 300 DEG C from 150 DEG C of risings, and the L acid of each catalyst all obviously reduces, and the B acid of Cu/Ce-Co-O catalyst and Cu/Ce-Co-La-O catalyst is all slightly reduce, and this shows that the intensity of B acid is greater than L acid.
According to the report of document, C on copper-based catalysts
3h
6rate-determining steps in selective reduction NO course of reaction carries out in B acid position, and first NO is activated in B acid position; B acid can promote the activation of hydrocarbon reductant, is conducive to C
3h
6selective reduction NO.Can be thought by Fig. 5 and Fig. 6, effectively can increase B acid acid amount owing to adding Co, and the intensity of B acid be comparatively large, thus effectively impels the activity of Cu/Ce-Co-O catalyst to significantly improve; And add La can increase further B acid acid amount, so the activity being conducive to Cu/Ce-Co-La-O catalyst improves further.
The catalyst obtained to above-mentioned 2 embodiments carries out TG test analysis
Thermogravimetric analysis (TG) is carried out on Japanese Shimadzu Corporation TGA-50 type thermogravimetric analyzer.Nitrogen flow 20 mL/min, heating rate 10 DEG C/min.
Fig. 7 is the TG test result of Cu/Ce-Co-O and Cu/Ce-Co-La-O catalyst, and b is the thermogravimetric curve of Cu/Ce-Co-O catalyst, and c is the thermogravimetric curve of Cu/Ce-Co-La-O catalyst.As shown in Figure 7, the thermal weight loss process of 2 catalyst can be roughly divided into two stages.First stage is at 30 ~ 870 DEG C, is catalyst surface physical absorption water successively, chemical absorbed water removes the dehydration with surface hydroxyl.The weight loss of this period Cu/Ce-Co-O and Cu/Ce-Co-La-O catalyst reaches 3.22% and 2.37% respectively.Second stage is at 870 ~ 1000 DEG C, mainly some Lattice Oxygen remove, part Ce species sintering, cause the component of part-structure to lose.The weight loss of this period Cu/Ce-Co-O and Cu/Ce-Co-La-O catalyst reaches 2.72% and 1.65% respectively.
The catalyst obtained to above-mentioned 2 embodiments carries out SEM test analysis
The SEM (JSM-6360LA) that SEM (SEM) test is produced in company of NEC (JEOL) is carried out.
Fig. 8 is the SEM photo of Cu/Ce-Co-O catalyst, and Fig. 9 is the SEM photo of Cu/Ce-Co-La-O catalyst, and demonstrate the exterior appearance of each catalyst and the size of catalyst granules, each catalyst granules is made up of some crystal grain.Cu/Ce-Co-O catalyst granules is obviously little, but obviously occurs agglomeration, and this shows that the interpolation of Co can suppress catalyst granules to be grown up, but is difficult to suppress agglomeration; The remarkable refinement of Cu/Ce-Co-La-O catalyst granules, more even, this shows that the interpolation of La can effectively reduce the agglomeration of crystal grain.The refinement of catalyst granules, can stop active component clustering, will be conducive to the absorption of reactant molecule at catalyst surface, activation and reaction.
Claims (10)
1. a preparation method for copper base cerium cobalt lanthanium complex oxide catalyst, is characterized in that, comprise the following steps:
A. compound concentration is the (NH of 1-2mol/L
4)
2cO
3or NH
4hCO
3the aqueous solution, regulates its pH=8-12 with the ammoniacal liquor of mass concentration 20-35%;
B. water-soluble cerium salt, water soluble cobaltous salt and water soluble lanthanum salt are pressed Ce
3+, Co
2+, La
3+the ratio of mol ratio 1 ︰ 0.06-0.2 ︰ 0-0.1 adds water and is mixed with the mixing salt solution of concentration of metal ions summation 0.2-0.3mol/L;
C. by (NH
4)
2cO
3or NH
4hCO
3solution is heated to 30-40 DEG C, under stirring, by (NH
4)
2cO
3or NH
4hCO
3the ratio of metal ion summation 3 ︰ 1-2 in molal quantity and mixing salt solution, slow instillation mixing salt solution, ageing suction filtration after 4-16 hours after instillation completely, the solids that reaction generates is in 500-750 DEG C of roastings after 100-150 DEG C of dryings, and after cooling, grinding obtains Ce-Co-La-O composite oxide carrier;
After the copper salt solution of D.Ce-Co-La-O composite oxide carrier dipping 0.01-0.1 mol/L, in 100-150 DEG C of dryings, in 450-650 DEG C of roastings after grinding, obtain Cu/Ce-Co-La-O catalyst.
2. the preparation method of copper base cerium cobalt lanthanium complex oxide catalyst according to claim 1, is characterized in that, in steps A, and mixed solution pH=9-11 be made into.
3. the preparation method of copper base cerium cobalt lanthanium complex oxide catalyst according to claim 1, it is characterized in that, in step B, water-soluble cerium salt is cerous nitrate, cerous sulfate or cerium chloride.
4. the preparation method of copper base cerium cobalt lanthanium complex oxide catalyst according to claim 1, it is characterized in that, in step B, water soluble cobaltous salt is cobalt nitrate, cobaltous sulfate or cobalt chloride.
5. the preparation method of copper base cerium cobalt lanthanium complex oxide catalyst according to claim 1, it is characterized in that, in step B, water soluble lanthanum salt is lanthanum nitrate, lanthanum sulfate or lanthanum chloride.
6. the preparation method of copper base cerium cobalt lanthanium complex oxide catalyst according to the arbitrary claim of claim 1-5, is characterized in that, in step B, and Ce
3+, Co
2+, La
3+mol ratio 1 ︰ 0.09-0.11 ︰ 0.05-0.07.
7. the preparation method of copper base cerium cobalt lanthanium complex oxide catalyst according to the arbitrary claim of claim 1-6, it is characterized in that, in step C, after the solids that reaction generates carries out described drying, impregnating effect concentration is the aqueous hydrogen peroxide solution of 2-20% again, then carries out described roasting.
8. the preparation method of copper base cerium cobalt lanthanium complex oxide catalyst according to claim 1, it is characterized in that, in step D, mantoquita is copper nitrate, copper sulphate or copper chloride.
9. the preparation method of copper base cerium cobalt lanthanium complex oxide catalyst according to claim 1 or 8, it is characterized in that, in step D, the concentration of mantoquita is 0.04-0.06 mol/L.
10. the catalyst that either method described in claim 1-9 is obtained.
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