CN102527373A - A kind of SCR denitrification catalyst with TiO2 as carrier - Google Patents

Abstract

The object of the present invention is to provide a SCR denitration catalyst with _TiO2 as the carrier and a manufacturing method thereof, which does not need to add reinforcing materials and has high catalytic activity. The catalyst uses barium-added TiO ₂ as a carrier, wherein the mass percentage of barium oxide is 5% to 20%; V ₂ O ₅ is the active component of the catalyst. The barium-added TiO ₂ accounts for 95%-99% by mass of the active components of the catalyst; the ammonium metavanadate is used as the V ₂ O ₅ precursor, and the V ₂ O ₅ accounts for 1%-5% by mass of the active components of the catalyst. Because the catalyst of the present invention does not need to add reinforcing materials during preparation, the active ingredients are more concentrated and the activity is stronger, which is one of the major breakthroughs of the present invention compared with the prior art. In addition, the catalyst of the invention has good formability and high strength. The SCR denitrification catalyst of the present invention has high catalytic activity. Its catalytic activity was tested in the simulated flue gas composition in the laboratory. NH3 was used as the reducing agent, the concentration was 1000ppm, the space velocity was 6000h ^-1 , the _NOx concentration was 1000ppm, and the volume of _O2 The percentage is 5%, and the rest is nitrogen. When the temperature range is 300°C-450°C, the conversion rate of nitrogen oxides is 80%-99%.

Description

A kind of SCR denitrification catalyst with TiO2 as carrier

technical field

The invention belongs to the field of chemical industry, and in particular relates to an SCR denitration catalyst with TiO2 as a carrier and a manufacturing method thereof. the

Background technique

Nitrogen oxides (NOx) are the main air pollutants, which can cause acid rain, photochemical smog, greenhouse effect and the destruction of the ozone layer. At present, my country's thermal power plants emit more than 10 million tons of nitrogen oxides every year, accounting for more than half of all nitrogen oxide emissions. Various regulations and policies to strengthen the limitation of nitrogen oxide emissions are being formulated or will be introduced soon, so the technology of controlling nitrogen oxide emissions has also received extensive attention from all walks of life. the

There are two ways to reduce NOx emissions: combustion process control and post-combustion flue gas denitrification. After adopting low-nitrogen combustion technology, the nitrogen oxide emission concentration of the unit still does not reach the emission standard limit, and a flue gas denitrification device should be added. Flue gas denitration technology mainly includes selective non-catalytic reduction technology (SNCR) and selective catalytic reduction technology (SCR). The process of SNCR technology is simple, but the denitrification efficiency of this process is low, only about 50%, which is difficult to meet the requirements of large coal-fired boilers with high environmental protection requirements. Compared with other technologies, SCR technology has the characteristics of low cost and high efficiency, and is currently the mainstream of denitrification technology in the world. the

The core of SCR technology is a high-performance catalyst. There are three types of catalysts: plate type, honeycomb type and corrugated plate type. Compared with plate type catalysts, honeycomb type catalysts can easily adjust the pore diameter of the honeycomb by changing the extruder mold, thereby increasing the surface area. , so the application range is wider, and a higher denitrification efficiency is obtained at a very high space velocity (GHSV), and its market rate accounts for 70%. the

At present, there are dozens of patents for denitrification catalysts in China. From the published patents, it can be seen that the commonly used carriers include TiO ₂ , Al ₂ O ₃ , molecular sieves, activated carbon, etc. Among them, TiO ₂ is the most widely used because of its high catalytic activity. widely. Nano- _TiO2 powder has poor formability, so some materials are used as reinforcing components or as matrix. Publication number is CN101474565A invention patent report adopts glass fiber as reinforcing component to manufacture honeycomb catalyst. Publication number is that the patent of invention of CN101396656A uses clay and glass fiber as the most reinforcing body. The publication number is CN101185886A patent of invention. Al ₂ O ₃ -SiO ₂ -TiO ₂ is used as a composite carrier to coat the cordierite honeycomb ceramic substrate and then load active components by impregnation. The invention patent with the publication number CN1792431A uses cordierite honeycomb ceramics as the skeleton material, double oxides Al ₂ O ₃ and TiO ₂ as the composite carrier, Al ₂ O ₃ as the inner layer carrier, and TiO ₂ as the outer layer carrier, impregnated with active components . Although the reinforcing material improves the mechanical strength of the catalyst, its active ingredient content is small and the catalytic activity is reduced.

Contents of the invention

The object of the present invention is to provide an SCR denitration catalyst with TiO2 as the carrier and a manufacturing method thereof, which does not need to add reinforcing materials, has good formability, high strength and high catalytic activity. the

Catalyst active ingredient of the present invention is:

With barium-added TiO ₂ as the carrier, the mass percentage _of barium oxide is 5% to 20%; V ₂ O ₅ is the active component of the catalyst, and the mass percentage of the active component of the catalyst is 1% to 5% based on V ₂ O 5 %.

The barium-added TiO ₂ accounts for 95%-99% by mass of the active components of the catalyst; the ammonium metavanadate is used as the V ₂ O ₅ precursor, and the V ₂ O ₅ accounts for 1%-5% by mass of the active components of the catalyst.

Catalyst preparation method of the present invention comprises the following steps:

1) Mixing process:

Based on V ₂ O ₅ , the mass percentage of active ingredients in the catalyst is 1% to 5%. Weigh ammonium metavanadate, fully mix and dissolve ammonium metavanadate and oxalic acid, add barium-type TiO ₂ and forming aids, and stir mechanically Until the mixture is evenly mixed, the liquid content of the mixture is about 20%-50% by mass.

The barium-added TiO ₂ is barium-added TiO ₂ with a barium oxide mass percentage of 5% to 20%, and the barium-added TiO ₂ accounts for 95% to 99% by mass of the active components of the catalyst.

Described forming aid comprises binding agent, plasticizer, lubricant and solvent, and wherein preferred scheme is as follows:

The binder is polyvinyl alcohol, the degree of polymerization n is 1500-1700, and the dosage is 5g-50g/1kg active ingredient of the catalyst;

Glycerin is used as a plasticizer and lubricant, and the dosage is 5g-50g/1kg active ingredient of the catalyst;

Water is used as a solvent, and the dosage is 200ml-1000ml/1kg of catalyst active ingredients. the

2) Extrusion molding process:

Step 1) The obtained mixture is extruded through a filter extruder and filtered to remove larger particles in the mixture, and then vacuum refined by a bipolar mud refiner to remove the gas adsorbed in the mud, and the refined mud is stale, and then passed through The vacuum extrusion molding machine extrudes the honeycomb ceramic catalyst billet. The preferred parameters are as follows:

The extrusion pressure of the filter extruder is 8MPa; stale for 2-8 hours; and then extruded into a honeycomb ceramic catalyst billet through a vacuum extrusion molding machine, the extrusion pressure is 8-12MPa, and the extrusion speed is 0.5-2m/min. the

3) Drying process:

After the above-mentioned catalyst blank is dried, moisture is removed, and the preferred parameters are as follows:

The catalyst blank is dried in a drying room, the temperature is controlled at 80°C-120°C, the heating rate is 10-50°C/hour, the humidity is controlled at 20%-70%, and the blank is dried for 8-12 hours. the

4) Firing process:

After drying, the catalyst is fired into a finished product, and its preferred parameters are as follows:

The above-mentioned catalysts are fired in a shuttle kiln with a heating rate of 1-10°C/min, rising from 100°C to the firing temperature, the firing temperature is 450°C-550°C, and the firing temperature is stable for 2-6 hours. to 100°C. the

Because the catalyst of the present invention does not need to add reinforcing materials during preparation, the active ingredients are more concentrated and the activity is stronger, which is one of the major breakthroughs of the present invention compared with the prior art. In addition, the catalyst of the invention has good formability and high strength. The SCR denitrification catalyst of the present invention has high catalytic activity. Its catalytic activity was tested in the simulated flue gas composition in the laboratory. NH3 was used as the reducing agent, the concentration was 1000ppm, the space velocity was 6000h ^-1 , the _NOx concentration was 1000ppm, and the volume of _O2 The percentage is 5%, and the rest is nitrogen. When the temperature range is 300°C-450°C, the conversion rate of nitrogen oxides is 80%-99%.

Detailed ways

The present invention will be further described below through specific examples. the

Example 1:

Weigh _400g of ammonium _metavanadate , 600g of oxalic acid, 30L of water, 500g of polyvinyl alcohol, 500g of glycerin, mix and dissolve fully, and add 30kg of barium oxide with a percentage content of 20%. Add barium-type TiO ₂ powder and mix with mechanical stirring for 1 hr. The mixture is filtered through a filter extruder, and then vacuum-refined through a mud mill, and the resulting mud is stale for 2 hours. Then it is extruded into a honeycomb ceramic billet through a vacuum extruder, and the extrusion pressure is 10 MPa. The billet enters the drying chamber and is dried at 100°C for 12 hours. The dried billet is fired in a shuttle kiln with a heating rate of 1°C/min, rising from 100°C to the firing temperature at 450°C, keeping the firing temperature stable for 4 hours, and then cooling the furnace to below 100°C.

Example 2:

Weigh _2000g of ammonium _metavanadate , 3000g of oxalic acid, 30L of water, 500g of polyvinyl alcohol, 500g of glycerin, fully mix and dissolve, and add 30kg of barium oxide with a percentage content of 20%. Add barium-type TiO ₂ powder and mix with mechanical stirring for 1 hr. The mixture is filtered through a filter extruder, and then vacuum-refined through a mud mill, and the resulting mud is stale for 4 hours. Then it is extruded into a honeycomb ceramic billet through a vacuum extruder, and the extrusion pressure is 12 MPa. The billet enters the drying chamber and is dried at 100°C for 12 hours. The dried billets are fired in a shuttle kiln with a heating rate of 1°C/min, rising from 100°C to the firing temperature at 500°C, keeping the firing temperature stable for 4 hours, and then cooling the furnace to below 100°C.

Example 3:

Weigh _400g of ammonium _metavanadate , 600g of oxalic acid, 20L of water, 1500g of polyvinyl alcohol, 1500g of glycerin, fully mix and dissolve, and add 30kg of barium oxide with a percentage content of 5% Add barium-type TiO ₂ powder and mix with mechanical stirring for 1 hr. The mixture is filtered through a filter extruder, and then vacuum-refined through a mud mill, and the resulting mud is stale for 4 hours. Then it is extruded into a honeycomb ceramic billet through a vacuum extruder, and the extrusion pressure is 10 MPa. The billet enters the drying chamber and is dried at 100°C for 8 hours. The dried billet is fired in a shuttle kiln with a heating rate of 2°C/min, rising from 100°C to the firing temperature at 450°C, keeping the firing temperature stable for 6 hours, and then cooling the furnace to below 100°C.

Example 4:

Weigh _2000g of ammonium _metavanadate , 3000g of oxalic acid, 30L of water, 1500g of polyvinyl alcohol, 1500g of glycerin, fully mix and dissolve, and add 30kg of barium oxide with a percentage content of 5%. Add barium-type TiO ₂ powder and mix with mechanical stirring for 1 hr. The mixture is filtered through a filter extruder, and then vacuum-refined through a mud mill, and the resulting mud is stale for 4 hours. Then it is extruded into a honeycomb ceramic billet through a vacuum extruder, and the extrusion pressure is 12 MPa. The billet enters the drying chamber and is dried at 100°C for 12 hours. The dried billet is fired in a shuttle kiln with a heating rate of 1°C/min, rising from 100°C to the firing temperature at 500°C, keeping the firing temperature stable for 4 hours, and then cooling the furnace to below 100°C.

The catalytic activity of the catalysts described in Examples 1 to 4 was tested in a laboratory simulated flue gas composition, with NH ₃ as the reducing agent, the concentration was 1000ppm, the space velocity was 6000h ^-1 , the _NOx concentration was 1000ppm, O ₂ Under the condition that the volume percentage is 5%, and the rest is nitrogen, the nitrogen oxide conversion rate of the catalyst at different temperatures is shown in Table 1.

Table 1 Nitrogen oxide conversion rate/% of catalyst at different temperatures

Claims (5)

1. one kind with TiO ₂Be the SCR denitrating catalyst of carrier, it is characterized in that to add barium type TiO ₂Be carrier, wherein barium monoxide quality percentage composition is 5%～20%; V ₂O ₅Be the catalyst activity composition.

2. according to claim 1 with TiO ₂Be the SCR denitrating catalyst of carrier, it is characterized in that adding barium type TiO ₂Accounting for catalyst active ingredient mass percent is 95%～99%; With the ammonium metavanadate is V ₂O ₅Presoma, V ₂O ₅Accounting for catalyst active ingredient mass percent is 1%～5%.

3. claim 1 is described with TiO ₂Preparation method for the SCR denitrating catalyst of carrier is characterized in that may further comprise the steps:

(1) with V ₂O ₅The mass percent that calculating accounts for catalyst active ingredient is 1%～5% to take by weighing ammonium metavanadate, with ammonium metavanadate and the abundant mixed dissolution of oxalic acid, adds barium type TiO ₂And shaping additive, mechanical agitation is to mixing, and the content liquid of mixture is about 20%～50% mass percent.

(2) larger particles in the mixture is extruded and removed by filter to the mixture that obtains of step 1) through filtering extruder; Again through bipolar pug mill vacuum refining; Remove the gas that adsorbs in the pug, the pug after the refining carries out old, is squeezed into the ceramic honeycomb catalyst blank through the vacuum extruding form machine again;

(3) remove moisture after the above-mentioned catalyst blank drying;

(4) dry rear catalyst is fired into finished product.

4. as claimed in claim 3 with TiO ₂Be the preparation method of the SCR denitrating catalyst of carrier, it is characterized in that described in the step 1) that in the shaping assistant, adhesive is a polyvinyl alcohol, extent of polymerization n is 1500～1700, and consumption is 5g～50g/1kg catalyst active ingredient; Glycerine is plasticizer and lubricant, and consumption is 5g～50g/1kg catalyst active ingredient; Water is solvent, and consumption is 200ml～1000ml/1kg catalyst active ingredient.

5. as claimed in claim 3 with TiO ₂Preparation method for the SCR denitrating catalyst of carrier is characterized in that adding described in the step 1) barium type TiO ₂Be barium monoxide quality percentage composition be 5%～20% add barium type TiO ₂, add barium type TiO ₂Accounting for catalyst active ingredient mass percent is 95%～99%.