CN102049257B - Catalyst for simultaneously reducing SO2 and NO with CO as well as preparation and application of catalyst - Google Patents

Abstract

The invention discloses a catalyst for simultaneously reducing SO2 and NO with CO as well as a preparation method of the catalyst. In the catalyst, a TiO2-Al2O3 compound is used as a carrier, wherein the weight of TiO2 accounts for 5-20% of the weight of the carrier; and an active component is one or more of transition metal oxides, and the load amount of the active component is 5-30% based on an oxide by weight. The catalyst is prepared by the following steps: firstly, adopting an immersion method to load TiO2 on Al2O3; and then introducing active component through a precursor solution used for immersing the active component. The catalyst has high activity in the reaction that SO2 and NO are reduced by CO at the same time; and under the lower reaction temperature and high airspeed, the conversion rate of SO2 can reach 98%, and the conversion rate of NO is nearly 100%.

Description

CO reduces SO simultaneously 2Catalyst and preparation and application with NO

Technical field

The present invention relates to a kind of SO that reduces simultaneously ₂With the Catalysts and its preparation method of NO, relate in particular to a kind of CO and reduce SO simultaneously ₂Catalysts and its preparation method and application with NO.

Background technology

Sulfur dioxide (SO ₂) and nitrogen oxide (NOx) be the major pollutants of atmosphere, they can produce acid rain, form photochemical fog, destroy ozone, bring great harm for environment and human health.China is to be the country of main energy sources with the coal, and the SO in the flue gas discharges in the coal-burning power plant ₂Account for 90% of total amount with NOx, all the other come from discharged flue gas in the industrial production such as petroleum refining.At present, the annual SO of China ₂Discharge capacity surpassed 2,500 ten thousand tons, become SO in the world ₂The first discharging big country; The discharge capacity in NOx every year has also surpassed 1,000 ten thousand tons.Desulphurization denitration is the key subjects of China's air contaminant treatment.

Using at present flue gas desulfurization and denitration technique more widely in the world and be traditional desulfur technology (FGD) the combined selective catalytic reduction technology (SCR) of application works alone separately and removes SO in the flue gas respectively ₂Combined desulfurization and denitration technology with NOx.For example: lime/lime stone-SCR technology and SNOX ^TMTechnology.The combined desulfurization and denitration technology generally all has comparatively ideal denitrification efficiency, but owing to adopt two covering devices to carry out desulfurization and denitration respectively, has therefore that floor space is big, flow process is complicated, investment and shortcomings such as operating cost height, secondary pollution.

Therefore usually contain CO in the flue gas, utilize CO in the flue gas to reduce SO simultaneously ₂With NO be elemental sulfur and N ₂Not only can eliminate these three kinds of pollutants simultaneously, and this technical process is simple, no waste liquid and waste residue, the catalyst with high activity, selectivity and stability is the core place of this technology.

US 5853684 discloses a kind of CO and has reduced SO simultaneously ₂With the catalyst of NO, this catalyst is the oxysulfide of transition metal and rare earth metal, as CoS ₂-La ₂O ₂S.This catalyst desired reaction temperature height, at 500 ℃, SO ₂Conversion ratio be 98%, the NO conversion ratio is 100%.

CN 1288773A discloses a kind of CO and has reduced SO simultaneously ₂With the catalyst of NO, this catalyst is the tin ash of coprecipitation preparation and the composite oxides of titanium dioxide.The disclosed catalyst of CN 1288774A is carrier with titanium dioxide, and active component is the oxide of cobalt and nickel, and the auxiliary activity component is molybdenum, tungsten and rare earth metal.More than two kinds of catalyst all can get 98% SO at 350 ℃ ₂Conversion ratio and 100% NO conversion ratio, but reaction velocity is low, has only 8000h ^-1

At present, relevant both at home and abroad CO reduces SO simultaneously ₂Less with the patent of NO catalyst, there is the high and low shortcoming of air speed of reaction temperature in the catalyst of existing publication.

Summary of the invention

At the deficiencies in the prior art, the invention provides a kind of CO and reduce SO simultaneously ₂With the catalyst of NO, this catalyst reduces SO simultaneously to CO ₂Reaction has very high activity with NO, under lower reaction temperature and high-speed, can get 98% SO ₂Conversion ratio and the NO conversion ratio that is close to 100%.

The invention provides a kind of CO and reduce SO simultaneously ₂With the catalyst of NO, described catalyst comprises:

(1) carrier: with TiO ₂-Al ₂O ₃Compound is a carrier, TiO ₂Spread loads is in Al ₂O ₃Surface, wherein TiO ₂Weight content in carrier is 5%～25%, is preferably 5%～20%;

(2) active component: the activity of such catalysts component is one or more in the transition metal oxide, and the content of active component counts 1%～35% with oxide, is preferably 5%～30%.

Wherein said Al ₂O ₃Be γ-Al ₂O ₃

Wherein said transition metal is selected from one or more among Fe, Co, Ni, Cu, Mo and the W.

According to a second aspect of the invention, also provide the preparation method of above-mentioned reducing catalyst, said method comprising the steps of:

(1) at first with Al ₂O ₃Impregnated in TiO ₂Precursor solution in, obtain TiO after drying and the roasting ₂-Al ₂O ₃Complex carrier;

(2) TiO that step (1) is prepared ₂-Al ₂O ₃Complex carrier impregnated in the salting liquid of transition metal, and drying and roasting obtain the catalyst of carrying transition metal oxide.

According to method provided by the invention, the TiO described in the step (1) ₂Precursor solution is selected from one group of material that ethanolic solution, titanium sulfate aqueous solution or the aqueous solution of titanyle sulfate of ethanolic solution, the titanium tetrachloride of butyl titanate are formed.

100～120 ℃ of baking temperatures described in step (1) and the step (2), 6～12 hours drying times; Described sintering temperature 400-600 ℃, roasting time 2～5 hours.

Transition metal described in the step (2) is selected from one or more among Fe, Co, Ni, Cu, Mo, the W.The salting liquid of described transition metal generally includes: the nitrate of Fe, Co, Ni, Cu, sulfate; Ammonium molybdate; Ammonium tungstate.

According to a third aspect of the present invention, the present invention also provides a kind of described catalyst to reduce SO simultaneously at CO ₂With the application among the NO: above-mentioned catalytic reduction catalysts is placed reactor, feeds CO, SO ₂The reaction gas of forming with NO reacts, and wherein reaction temperature is 320～350 ℃, and reaction velocity is 5000h ^-1～20000h ^-1

According to the conventional method in this area, described catalyst can carry out presulfurization under 400～600 ℃ in the presence of sulfurous gas before using.This presulfurization can be carried out also can original position vulcanizing in device outside device, is translated into sulphided state.

Described sulfurous gas is H ₂S, SO ₂/ CO or SO ₂/ H ₂

Compared with prior art, the present invention has following characteristics:

1, catalyst of the present invention is with TiO ₂The Al of modification ₂O ₃Be carrier, through TiO ₂After the modification, the pore volume of complex carrier and specific area also further increase.After reactive metal loads to this complex carrier, disperse more evenly, thereby the more existing reducing catalyst of activity of such catalysts is significantly improved.And Preparation of catalysts method of the present invention is simple, and flow process is simple.

2, sulfur dioxide and nitrogen oxide during reducing catalyst of the present invention can remove smoke simultaneously can be simplified the process for purifying of purifying contaminated gas significantly.Reducing catalyst of the present invention is used for CO and reduces SO simultaneously ₂When reacting, shown high reactivity with NO.Catalyst of the present invention is (20000h under lower temperature (320 ℃) and high-speed ^-1) can obtain 98% SO ₂Conversion ratio and the NO conversion ratio that is close to 100%.

The specific embodiment

The specific embodiment of the present invention will be described in more detail technical scheme of the present invention by following examples, and described embodiment should not be construed as the restriction of the scope of the invention.

Embodiment 1

With Al ₂O ₃Impregnated in the ethanolic solution of an amount of butyl titanate, stir evaporate to dryness, left standstill 12 hours, through 100 ℃ of dryings 12 hours, 500 ℃ of roastings obtained TiO after 4 hours ₂-Al ₂O ₃Complex carrier;

With TiO ₂-Al ₂O ₃Complex carrier impregnated in the iron nitrate aqueous solution, stirs evaporate to dryness, and through 110 ℃ of dryings 12 hours, 600 ℃ of roastings obtained the catalyst of load iron oxide in 2 hours, were numbered C ₁

Above-mentioned catalyst under 400 ℃, is fed H ₂S gas cure 5 hours.

In the gained catalyst, TiO ₂Account for 5% of vehicle weight; The iron oxide load capacity is 5%.

Embodiment 2

With Al ₂O ₃Impregnated in the ethanolic solution of an amount of titanium tetrachloride, stir evaporate to dryness, left standstill 12 hours, through 110 ℃ of dryings 8 hours, 600 ℃ of roastings obtained TiO after 2 hours ₂-Al ₂O ₃Complex carrier;

With TiO ₂-Al ₂O ₃Complex carrier impregnated in an amount of cobalt nitrate aqueous solution, stirs evaporate to dryness, and through 100 ℃ of dryings 12 hours, 500 ℃ of roastings obtained the catalyst of load cobalt oxide in 3 hours, were numbered C ₂

Above-mentioned catalyst under 500 ℃, is fed H ₂S gas cure 3 hours.

In the gained catalyst, TiO ₂Account for 15% of vehicle weight; The supported by cobalt oxide amount is 10%

Embodiment 3

With Al ₂O ₃Impregnated in the aqueous solution of an amount of titanium sulfate, stir evaporate to dryness, left standstill 12 hours, through 120 ℃ of dryings 6 hours, 400 ℃ of roastings obtained TiO after 5 hours ₂-Al ₂O ₃Complex carrier;

With TiO ₂-Al ₂O ₃Complex carrier impregnated in an amount of cobalt nitrate and the ammonium molybdate mixed aqueous solution, stirs evaporate to dryness, and through 120 ℃ of dryings 6 hours, 400 ℃ of roastings obtained the catalyst of load cobalt oxide and molybdenum oxide in 5 hours, were numbered C ₃

Above-mentioned catalyst under 500 ℃, is fed SO ₂/ CO gas cure 5 hours.

In the gained catalyst, TiO ₂Account for 10% of vehicle weight; The supported by cobalt oxide amount is 10%, the molybdenum oxide load capacity is 10%.

Embodiment 4

With Al ₂O ₃Impregnated in the aqueous solution of an amount of titanyl sulfate, stir evaporate to dryness, left standstill 12 hours, through 100 ℃ of dryings 12 hours, 500 ℃ of roastings obtained TiO after 5 hours ₂-Al ₂O ₃Complex carrier;

With TiO ₂-Al ₂O ₃Complex carrier impregnated in an amount of nickel nitrate aqueous solution, stirs evaporate to dryness, and through 120 ℃ of dryings 6 hours, 600 ℃ of roastings obtained the catalyst of load nickel oxide in 3 hours, were numbered C ₄

Above-mentioned catalyst under 600 ℃, is fed SO ₂/ H ₂Gas cure 3 hours.

In the gained catalyst, TiO ₂Account for 20% of vehicle weight; Nickel oxide loaded amount is 30%.

Embodiment 5

With Al ₂O ₃Impregnated in the aqueous solution of an amount of titanium sulfate, stir evaporate to dryness, left standstill 12 hours, obtain TiO after drying and the roasting ₂-Al ₂O ₃Complex carrier;

With TiO ₂-Al ₂O ₃Complex carrier impregnated in an amount of ferric nitrate and nickel nitrate aqueous solution, stirs evaporate to dryness, and drying and roasting obtain the catalyst of load nickel oxide, are numbered C ₅

Above-mentioned catalyst under 400 ℃, is fed SO ₂/ H ₂Gas cure 3 hours.

In the gained catalyst, TiO ₂Account for 20% of vehicle weight; The iron oxide load capacity is 10%, nickel oxide loaded amount is 10%.

Comparative example 1

According to CN1288774A embodiment 1 preparation catalyst C ₆, catalyst consists of: MoO ₃/ TiO ₂-Co ₃O ₄, wherein, the weight ratio of titanium dioxide and cobalt oxide is 1: 1, MoO ₃Account for 15% of catalyst total amount.

Comparative example 2

According to CN 1288773A embodiment 1 preparation catalyst C ₇, catalyst consists of: SnO ₂-TiO ₂, the weight ratio of tin ash and titanium dioxide is 1: 1..

Comparative example 3

Prepare catalyst C according to embodiment among the US 5853684 ₈, catalyst consists of: CoS ₂-La ₂O ₂S, the mass ratio of Co and La 2.3: 1.

Embodiment 6

The catalyst of embodiment 1-5 and comparative example 1-3 preparation reduces SO simultaneously at CO ₂With the application among the NO.Application test carries out on the small-sized evaluating apparatus in laboratory.The concentration of reaction gas is: SO ₂1200 μ L/L, NO 1000 μ L/L and CO 3400 μ L/L; Air speed: 20000h ^-1The elemental sulfur that reaction end gas generates by the cooling of frozen water cold-trap earlier is then through gas-chromatography HP-6890 on-line analysis, the SO in the tail gas ₂, CS ₂Separated by Gaspro Capillary capillary column with COS, FPD detects; CO and CO ₂Separated by Porapack Q packed column, TCD detects.N ₂Separate with the 5A molecular sieve, TCD detects.SO ₂Conversion ratio (X _SO2), the selectivity (Y of elemental sulfur _s), the yield (Y) and the NO conversion ratio (X of elemental sulfur _NO) calculate by following formula: result of the test is listed in the table 1.

$X_{\mathrm{SO}2}\frac{{\left[{\mathrm{SO}}_2\right]}_{\mathrm{in}}-{\left[S{O}_2\right]}_{\mathrm{out}}}{{\left[{\mathrm{SO}}_2\right]}_{\mathrm{in}}}*100\%$

$Y_s\frac{{\left[{\mathrm{SO}}_2\right]}_{\mathrm{in}}-{\left[S{O}_2\right]}_{\mathrm{out}}-{\left[\mathrm{COS}\right]}_{\mathrm{out}}-{\left[{\mathrm{CS}}_2\right]}_{\mathrm{out}}}{{\left[{\mathrm{SO}}_2\right]}_{\mathrm{in}}-{\left[S{O}_2\right]}_{\mathrm{out}}}*100\%$

Y＝XY _s

$X_{\mathrm{NO}}=\frac{2{\left[N_2\right]}_{\mathrm{out}}}{{\left[\mathrm{NO}\right]}_{\mathrm{in}}}*100\%$

Table 1

By the contrast experiment as can be known, catalyst of the present invention reduces SO than the catalyst of existing patent report simultaneously to CO ₂Reaction has better low temperature active with NO.

Claims (8)

1. a CO reduces SO simultaneously ₂Method with NO places reactor with catalytic reduction catalysts, feeds CO, SO ₂The reaction gas of forming with NO reacts, and wherein reaction temperature is 320～350 ℃, and reaction velocity is 5000h ^-1～20000h ^-1

Described catalytic reduction catalysts comprises: (1) carrier: with TiO ₂-Al ₂O ₃Compound is a carrier, TiO ₂Spread loads is in Al ₂O ₃Surface, wherein TiO ₂Weight content in carrier is 5%～25%; (2) active component: the activity of such catalysts component is one or more in the transition metal oxide, and the content of active component counts 1%～35% with oxide.

2. in accordance with the method for claim 1, it is characterized in that described catalytic reduction catalysts in the presence of sulfurous gas, carried out presulfurization before using under 400～600 ℃, described sulfurous gas is H ₂S, SO ₂/ CO or SO ₂/ H ₂

3. in accordance with the method for claim 1, it is characterized in that the preparation method of described catalytic reduction catalysts may further comprise the steps:

(1) at first with Al ₂O ₃Impregnated in TiO ₂Precursor solution in, obtain TiO after drying and the roasting ₂-Al ₂O ₃Complex carrier;

(2) TiO that step (1) is prepared ₂-Al ₂O ₃Complex carrier impregnated in the salting liquid of transition metal, and drying and roasting obtain the catalyst of carrying transition metal oxide.

4. in accordance with the method for claim 1, it is characterized in that described TiO ₂Weight content in carrier is 5%～20%, and the content of described active component in catalyst counts 5%～30% with oxide.

5. in accordance with the method for claim 1, it is characterized in that described transition metal is selected from one or more among Fe, Co, Ni, Cu, Mo and the W.

6. in accordance with the method for claim 3, it is characterized in that the TiO described in the step (1) ₂Precursor solution is selected from one group of material that ethanolic solution, titanium sulfate aqueous solution or the aqueous solution of titanyle sulfate of ethanolic solution, the titanium tetrachloride of butyl titanate are formed.

7. in accordance with the method for claim 3, it is characterized in that the baking temperature described in step (1) and the step (2) is 100～120 ℃, be 6～12 hours drying time; Described sintering temperature is 400～600 ℃, and roasting time is 2～5 hours.

8. in accordance with the method for claim 3, it is characterized in that the transition metal described in the step (2) is selected from one or more among Fe, Co, Ni, Cu, Mo, the W.