CN112427032B

CN112427032B - Catalyst for catalyzing and burning vinyl chloride to polymerize wet-containing tail gas and preparation method thereof

Info

Publication number: CN112427032B
Application number: CN201910788701.9A
Authority: CN
Inventors: 秦中宇; 徐彦龙; 梁高珲; 李允升; 朱文俊; 翟一鸣; 张宏科
Original assignee: Wanhua Chemical Group Co Ltd
Current assignee: Wanhua Chemical Group Co Ltd
Priority date: 2019-08-26
Filing date: 2019-08-26
Publication date: 2022-07-12
Anticipated expiration: 2039-08-26
Also published as: CN112427032A

Abstract

The invention provides a preparation method of a catalyst for catalyzing and incinerating wet tail gas containing vinyl chloride, which comprises the following preparation steps: (1) preparing active component doped precursor, dissolving mineral containing transition metal niobium with acid, adding fluosalt, fluoridizing and complexing to obtain doped precursor K₂[NbOF₅](ii) a (2) Preparing doped active component, MnO mixing with doped precursor K₂[NbOF₅]Mixing, controlling the pH value, adding alkali for coprecipitation to generate an active component emulsion; (3) preparing and modifying a carrier, namely modifying the attapulgite of the carrier by using a modifier solution containing a silane coupling agent; (4) loading active component, vacuum immersing the emulsion of active component, calcining for shaping, and calcining for passivating. Proved by verification on an incineration platform, the catalyst prepared by the method has good effect of catalytic incineration of the wet tail gas containing the chloroethylene.

Description

Catalyst for catalyzing and burning vinyl chloride to polymerize wet-containing tail gas and preparation method thereof

Technical Field

The invention belongs to the field of chemical tail gas treatment, and particularly relates to a catalyst for catalyzing and incinerating vinyl chloride to polymerize wet tail gas and a preparation method thereof.

Background

The reaction conversion rate of polyvinyl chloride generated by vinyl chloride polymerization is about 80%, and the rest unreacted vinyl chloride is released from a polymerization kettle after the polymerization reaction is finished. For the treatment of the chlorine-containing tail gas (containing chlorine volatile organic compounds, CVOCs, containing a certain amount of moisture), the common practice in industry is to condense and recycle the tail gas, and then send the uncondensed gas to an incinerator for high-temperature incineration (above 1100 ℃), so that the energy consumption is high, and harmful substances such as CO, formaldehyde, formic acid, phosgene and the like can be generated to cause secondary pollution.

The CVOCs can be removed by a direct burning method, a catalytic hydrogenation and dechlorination method, a catalytic steam reforming method, a photocatalytic oxidation method, a catalytic combustion method and the like. Of these, catalytic combustion is the most economical and environmentally friendly. A plurality of related catalysts with certain activity, selectivity and stability have been developed. For such catalysts, the active component is generally selected from Mn, Cu, Cr, Fe and V oxides; the support is generally SiO₂、ZrO₂、CexZr-xO₂Solid solution, SiO₂、γ-Al₂O₃And zeolites, metal honeycombs, woven metal meshes, and the like, and among them, catalysts in which a molecular sieve and a woven metal mesh carrier are used as a carrier have been studied in many cases. However, due to improper selection of the carrier and the auxiliary agent, the problems of poor selectivity of the catalyst to a certain component, poor resistance to poisoning (active site deactivation), insufficient oxidation capacity and the like are easily caused, and the situation of poor catalytic effect is frequently seen.

Therefore, many scholars screen and verify active components or carriers in a large quantity, and some scholars dope simple substances or improve carriers on the active components to achieve the excellent catalysis purpose; weili (Master university paper, Tianjin university, 2007.06) examines the catalyst activity with VOx and/or WOx as active components, and proves that the catalyst has good carbon deposition resistance and chlorine poisoning resistance, but the selectivity of the catalyst is low. The result shows that the manganese-cerium oxide has better catalytic capability to common hydrocarbons CVOCs such as ethane, propane, normal hexane, benzene, toluene and the like or single component CVOC (dichloroethane). The catalytic effect of aqueous multicomponent CVOCs was not evaluated in depth.

CN201710423251 discloses a non-coated metal matrix monolithic catalyst carrier/catalyst, wherein the catalyst is a carrier, and a porous alumina layer is loaded with 0-10 wt% of noble metal elements. Can be applied to the catalytic combustion purification of the chlorine-containing volatile organic compounds such as DCM, o-DCB and the like in the waste gas in the field of atmospheric environmental protection. CN 107626327A provides a catalyst for dechlorination of carbon tetrachloride by passing through Al₂O₃The modified activated carbon is used as a carrier, Pt and metal M are used as active components, and the metal M is any one or more than two of Cr, Mn, Co and Ba. In both of the above patents, noble metals are used as active components, and although the amount used is not large, the cost is still high for industrial exhaust gas applications. CN109107567A discloses M-MnO_X-CeO₂Catalyst with MnO_X、CeO₂As an active component, FeOx, CuO, CoOx or K₂O is taken as a dopant, one of cordierite and spherical 4A or 13X molecular sieves is taken as a carrier, and the generated catalyst can be used for catalytic oxidation of gaseous formaldehyde under the normal temperature condition or thermal catalytic oxidation of CVOCs by adjusting a proper proportion. The invention considers the oxide doping of the active component, but still uses a single carrier, and the actual effect on the thermal catalysis of CVOCs is unknown.

In conclusion, dechlorination catalysts are researched more and more, the effect is different after the active components or carriers are changed, and the influence of the preparation process is also very critical. At present, a dechlorination catalyst with high catalytic activity, strong anti-poisoning capability and good economical efficiency and excellent comprehensive performance is difficult to prepare.

Disclosure of Invention

The reason why the existing dechlorination catalyst has problems is that: the catalytic reaction of CVOCs is divided into dehalogenation reaction and oxidation reaction, wherein the dehalogenation reaction is a control step and is determined by the acid position B or the acid position L of the active center of the catalyst, and the number of the acid positions influences the catalytic activity. In the actual catalytic reaction process, on one hand, the active center is easily covered due to carbon deposition of the active center, and reactant molecules cannot approach the acid site of B, so that the loss of the function of the acid site of B (namely, alkali poisoning) is one of the reasons for catalyst deactivation. On the other hand, the generated Cl reacts with active components (such as Cl-Mn, Cl-V combination), and the reduction of active components (i.e. chlorine poisoning) is another cause of the catalyst deactivation. In the support aspect, if the support is not properly selected, not only does it not provide a large active surface, but it may also increase the manufacturing cost of the industrial catalyst.

Aiming at the problems and reasons of the prior dechlorination catalyst, the invention aims to provide a preparation method of a catalyst for catalyzing and incinerating vinyl chloride to polymerize wet tail gas, and the catalyst obtained by the method has the advantages of high catalytic activity, obvious dechlorination effect, strong poisoning resistance, low carrier cost and special water-resistant effect.

In order to achieve the above purpose and achieve the above technical effects, the technical solution of the present invention is as follows:

a preparation method of a catalyst for catalyzing and incinerating vinyl chloride to polymerize wet tail gas comprises the following steps:

(1) preparing an active component doped precursor: dissolving mineral containing metal niobium with acid, adding fluorine salt, fluorinating and complexing to obtain doped precursor K₂[NbOF₅]；

(2) Preparing a doped active component: mixing active component MnO with doped precursor K₂[NbOF₅]Mixing, controlling the pH value, adding alkali for coprecipitation to generate active component emulsion;

(3) preparing and modifying a carrier: modifying a carrier Attapulgite (ATP) with a modifier solution containing a silane coupling agent;

(4) loading active components: vacuum soaking the modified carrier with the active component emulsion, roasting to form, deactivating with steam, cooling and other steps.

In the present invention, the metal-containing niobium mineral in the step (1) is refined niobium mineral, such as Nb₂O₅Refined niobium ore grade 36.48 wt%, the mineral dissolving acid being hydrofluoric acid, e.g. a 40 wt% hydrofluoric acid solution, and the fluoride salt being potassium fluoride, e.g. a 40 wt% potassium fluoride solution, wherein the niobium concentrate: hydrofluoric acid: the mass ratio of the potassium fluoride is 1 (3-5) to 0.8-1.

In the step (1), a transition metal element niobium is added, the niobium reacts with fluorine at room temperature, reacts with chlorine, hydrogen and air at about 200 ℃, reacts with hydrogen and nitrogen at about 400 ℃, is directly combined with sulfur, nitrogen and carbon at high temperature (>400 ℃), and can resist the corrosion of molten alkali and various acids. Therefore, at about 200 ℃, Cl generated by dechlorinating the chlorine-containing tail gas is firstly selected to react with niobium, and active elements (such as Mn) are not consumed; at high temperature (>400 ℃), carbon deposition generated by chlorine-containing organic matters is combined with niobium, so that the carrier can be well protected, and the carbon deposition is prevented from being attached to an active site, therefore, the addition of niobium can play a positive protection role on both the active component and the carrier, and meanwhile, the catalyst is prevented from being inactivated by alkali poisoning and chlorine poisoning.

In the invention, in the step (2), the active component MnO and the doped precursor K are₂[NbOF₅]Mixing according to the weight ratio of (10-50) g to 300 g; adding excess NH₄And controlling the pH value of OH to be 8-10. The blend prepared by the stepThe mixed active component contains niobium hydroxide, MnO, etc. and is a mixed emulsion.

In the invention, ATP used for modification in the step (3) is 200-300 mesh components, and the modifier solution comprises ethanol, hydrofluoric acid, aluminum nitrate, magnesium nitrate and a silane coupling agent in a volume ratio of 4:1:2:2: 1; the ratio of the dosage of the modifier solution to ATP is (1-2) L:100 g; the modification process is stirring for 30-60 min at 45-75 ℃, and drying at 90-110 ℃ after modification.

In the step (3), because ATP is a natural magnesium-aluminum-rich silicate clay mineral, the structural unit of ATP contains a large amount of SiO which can be used as a catalyst carrier₂MgO and gamma-Al₂O₃And is a natural mineral with a nano-channel structure. ATP is cheap and rich, has a large specific surface area, an excellent pore structure and ion exchange property, can effectively improve the effective active site of an acid catalyst in a catalytic reaction, is easy to regulate and control surface acidity, and has good adsorption performance. The preparation process of ATP powder in the step refers to a general method for preparing powder in patent CN 102794169B. Specifically, the attapulgite flakes are obtained by pre-stacking and homogenizing clay, mixing with water, and extruding and shearing with a roller or multiple rollers (this process is intended to disaggregate and disperse ATP crystal bundles). Then, the sheet-like material is dried and pulverized.

In the step (3), the modifier functions as follows: under a mutual dissolving system established by ethanol, a small amount of hydrofluoric acid plays a proper role in reducing silicon; the introduction of aluminum nitrate and magnesium nitrate can adjust the Si/Mg ratio and the Si/Al ratio, and the aim is to optimize the molecular structure of the carrier.

In the invention, the silane coupling agent in the step (3) is one or more of KH550, KH560, 570, Si-69 and LM-N308. The silane coupling agent is used for improving the wettability of the surface of the carrier, and the main principle is that silane is grafted with carrier molecules to enable the surface of the carrier to generate hydrophobic groups, so that the hydrophobic effect is achieved, and the 'water-resistant' effect is achieved when the water-containing organic matter is catalytically incinerated.

In the invention, when dipping is carried out in the step (4), the proportion of the doped active component emulsion to the modified carrier is (200-300) ml:100g, and the dipping time is 5-8 h. In the dipping process, the mixture is placed in a water bath environment of 80 ℃ for shaking so as to ensure that emulsion particles are fully contacted with the carrier, and the mixture is taken out for natural draining after dipping.

In the step (4), during the dipping process, colloidal particles (with negative charges) formed by the modified ATP in the solution interact with metal ion (Nb) hydrolysis hydroxide (with positive charges) in the active component emulsion, so that the doped active component is uniformly loaded on the surface of the modified ATP.

In the invention, the step (4) is roasted for 7-10 h at 550-700 ℃, air containing water vapor is introduced for passivation in the roasting stage, and the concentration of the water vapor is less than 800ppm based on the mass of the air containing the water vapor. The roasting process of the step is finished in a muffle furnace, and the roasting is naturally cooled to finish the preparation of the catalyst.

In the step (4), after the calcination, the doped active component is firmly combined with the carrier. After firing, Nb is converted from hydroxide to oxide structure (Nb)₂O₅) At this time, the passivation with water vapor (oxide with crystal water) of not more than 800ppm is used to form the niobic acid structure (Nb)₂O₅·nH₂O), the surface of the niobic acid contains a B acid center (Nb-OH) and a coordination unsaturated L acid center (Nb)⁵ ⁺)。Nb₂O₅The strength of B acid on the surface is greater than that of B acid on the surface of MnO, when the doping amount is increased, the proportion of Mn-O-Mn and Mn-O-Nb species is reduced, and the proportion of Nb-O-Nb species is increased.

Moreover, through the steam passivation step, the resistance effect of the catalyst on the moisture in the tail gas is enhanced again, and the catalytic effect is obviously enhanced.

Further, Nb contained in the calcined catalyst₂O₅The active element Mn is not easy to generate electron transfer and lose due to strong interaction with Mn metal, so that the electron cloud density of Mn is increased.

Another object of the present invention is to provide a catalyst prepared by the above preparation method.

A catalyst for tail gas incineration treatment is prepared by the preparation method.

The invention has the following positive effects:

(1) the doped active component prepared by introducing the metal niobium effectively prevents the loss of the active component and the carbon deposition of the active site, improves the anti-poisoning capability of the catalyst, and simultaneously avoids the alkali poisoning inactivation and the chlorine poisoning inactivation of the catalyst.

(2) A modified attapulgite carrier is selected, so that a larger active surface or acid site is provided, and meanwhile, the acid center of the catalyst B is enhanced through a water vapor passivation step, so that the activity of the catalyst is improved.

(3) The catalyst has good dechlorination effect on wet CVOCs, and can reduce chloroethylene in chloroethylene incineration tail gas to 20-41ppm and reduce chloromethane to 1-16 ppm.

Detailed Description

The following examples further illustrate the invention but are not to be construed as limiting the invention.

The sources of the raw materials and the reagents of the catalyst of the invention are detailed in the following table 1, and the reagents are all analytically pure (AR).

TABLE 1 catalyst raw materials and reagents

The catalytic incineration pilot plant is designed by itself, and relevant design parameters and evaluation conditions are detailed in the following table 2. The evaluation tail gas comes from a laboratory small-scale polymerization kettle, and the composition and the content are detailed in the following table 3. The related component analysis adopts Agilent 7890B type gas chromatography, a four-valve six-column sample injection system, and the test standard is GB/T16088-1995 chloroethylene direct sample injection gas chromatography determination method.

TABLE 2 incineration plant parameters

TABLE 3 composition of chlorine-containing tail gas

Composition (I)	Vinyl chloride	Water (I)	Carbon dioxide	Carbon monoxide	Methyl chloride	Nitrogen gas
							The content wt%	62	1.8	15	6	0.2	15

Example 1

(1) Preparing an active component doped precursor: taking 100g of refined niobium ore, adding 40 wt% hydrofluoric acid solution for dissolving, adding 40 wt% potassium fluoride solution into the solution after reaction, and controlling the niobium concentrate: hydrofluoric acid: reacting for 60min at room temperature with the mass ratio of potassium fluoride of 1:3:0.8 to obtain a doped component precursor K₂[NbOF₅]And (3) solution.

(2) Preparing a doped active component: 10g of active component MnO is dissolved in 300g of precursor solutionThen adding NH₄And (4) fully stirring and mixing OH until the pH value is controlled to be 8 for 20min to obtain the doped active component.

(3) Preparing and modifying a carrier: referring to the general method for preparing ATP powder in patent CN 102794169B example 1 (step 2-3), ATP powder with 200-300 meshes is screened out. Weighing 100g of powder, putting the powder into a water bath containing 1L of a modified solvent (the volume ratio of all substances in the solvent is ethanol: hydrofluoric acid: aluminum nitrate: magnesium nitrate: silane coupling agent is 4:1:2:2: 1; wherein the silane coupling agent is selected and the mass ratio of the silane coupling agent is KH550: KH560 is 1:1), setting the temperature at 45 ℃, magnetically heating and stirring for 30min, then cooling, filtering, washing with deionized water until the washing liquid becomes neutral, putting the washing liquid into a vacuum oven, and drying at 90 ℃ to complete the preparation of the modified carrier.

(4) Loading active components: according to the proportion of 200ml/100g of the doped active component emulsion and the modified carrier, vacuumizing and dipping for 5 hours under the condition of shaking in a water bath at 80 ℃. Taking out, draining, and roasting in a muffle furnace at 550 ℃ for 7 h. Air containing water vapor with the mass concentration of 700ppm is introduced for passivation during roasting. After roasting, the catalyst is naturally cooled, the catalyst is prepared and loaded into a catalytic incineration reactor.

The effect of catalytic incineration tail gas is shown in the following table 4:

TABLE 4 composition of chlorine-containing tail gas

Content/ingredient

Vinyl chloride

Water (W)

Carbon dioxide

Carbon monoxide

Methyl chloride

Nitrogen gas

Content before treatment (wt)

62％

1.8％

15％

6％

0.2％

15％

Content after treatment (wt)

25ppm

2％

83％

0

5ppm

15％

Example 2

(1) Preparing an active component doped precursor: controlling the fine niobium ore: hydrofluoric acid: the mass ratio of potassium fluoride was 1:3:1, and the other conditions were the same as in example 1.

(2) Preparing a doped active component: the same as in example 1.

(3) Preparing and modifying a carrier: KH-550 was selected as the silane coupling agent, and the other conditions were the same as in example 1.

(4) Loading active components: the same as in example 1.

The effect of catalytic incineration tail gas is shown in the following table 5:

TABLE 5 composition of chlorine-containing off-gas

Content/ingredient

Vinyl chloride

Water (I)

Carbon dioxide

Carbon monoxide

Methyl chloride

Nitrogen gas

Content before treatment (wt)

62％

1.8％

15％

6％

0.2％

15％

Content after treatment (wt)

27ppm

2％

83％

0

8ppm

15％

Example 3

(1) Preparing an active component doped precursor: 100g of the refined niobium ore is taken, added with a hydrofluoric acid solution with the concentration of 40 wt% for dissolution, a potassium fluoride solution with the concentration of 40 wt% is added into the reacted solution, and the niobium concentrate is controlled: hydrogenHydrofluoric acid: the mass ratio of the potassium fluoride is 1:4:1, and the mixture reacts for 60min at room temperature to obtain a doped component precursor K₂[NbOF₅]And (3) solution.

(2) Preparing a doped active component: 20g of active component MnO is dissolved in 300g of precursor solution, and then excessive NH is added₄And (4) fully stirring and mixing OH until the pH value is controlled to be 9 for 20min to obtain the doped active component.

(3) Preparing and modifying a carrier: refer to patent CN 102794169B example 1 (step 2-3) general method for preparing attapulgite powder, prepare 200-300 mesh ATP powder sieve component. Weighing 100g of powder, putting the powder into a water bath containing 1.5L of a modified solvent (the volume ratio of all substances in the solvent is ethanol: hydrofluoric acid: aluminum nitrate: magnesium nitrate: silane coupling agent is 4:1:2:2: 1; the selection and mass ratio of the silane coupling agent is KH550: KH560: LM-N308 is 1:1:1), setting the temperature to be 60 ℃, magnetically heating and stirring for 45min, then cooling, filtering, washing with deionized water until the washing liquid becomes neutral, putting the washing liquid into a vacuum oven, drying at the temperature of 100 ℃, and finishing the preparation of the modified carrier.

(4) Loading active components: according to the proportion of the doped active component emulsion to the modified carrier of 270ml/100g, vacuumizing and dipping for 7 hours under the shaking condition of water bath 80 ℃. Taking out, draining, and roasting in a muffle furnace at 600 deg.C for 9 h. Air containing water vapor with the mass concentration of 700ppm is introduced for passivation during roasting. Naturally cooling, finishing the preparation of the catalyst, and loading into a catalytic incineration reactor.

The effect of catalytic incineration tail gas is shown in the following table 6:

TABLE 6 composition of chlorine-containing tail gas

Content/ingredient

Vinyl chloride

Water (W)

Carbon dioxide

Carbon monoxide

Methyl chloride

Nitrogen gas

Content before treatment (wt)

62％

1.8％

15％

6％

0.2％

15％

Content after treatment (wt)

20ppm

2％

83％

0

1ppm

15％

Example 4

(1) Preparing an active component doped precursor: taking 100g of refined niobium ore, adding 40 wt% hydrofluoric acid solution for dissolving, adding 40 wt% potassium fluoride solution into the solution after reaction, and controlling the niobium concentrate: hydrofluoric acid: the mass ratio of the potassium fluoride is 1:5:1, and the mixture reacts for 60min at room temperature to obtain a doped component precursor K₂[NbOF₅]And (3) solution.

(2) Preparing a doped active component: 50g of active component MnO is dissolved in 300g of precursor solution, and then excessive NH is added₄OH until pH is controlled to 10, and stirring thoroughlyMixing for 20min to obtain doped active component.

(3) Preparing and modifying a carrier: refer to patent CN 102794169B example 1 (step 2-3) general method for preparing attapulgite powder, prepare 200-300 mesh ATP powder sieve component. Weighing 100g of powder, putting the powder into a water bath containing 2L of a modified solvent (the volume ratio of all substances in the solvent is ethanol: hydrofluoric acid: aluminum nitrate: magnesium nitrate: silane coupling agent is 4:1:2:2: 1; the silane coupling agent is selected and the mass ratio is KH550: KH560: 570: 1:1), setting the temperature to be 75 ℃, magnetically heating and stirring for 60min, then cooling, filtering, washing with deionized water until the washing liquid becomes neutral, putting the washing liquid into a vacuum oven, drying at 110 ℃, and preparing the modified carrier.

(4) Loading active components: according to the proportion of the doped active component emulsion to the modified carrier of 300ml/100g, the vacuum-pumping immersion time is 8h under the condition of shaking in a water bath at 80 ℃. Taking out, draining, and roasting in a muffle furnace at 700 ℃ for 10 h. Air containing water vapor with the mass concentration of 700ppm is introduced for passivation during roasting. Naturally cooling, finishing the preparation of the catalyst, and loading into a catalytic incineration reactor.

The effect of catalytic incineration tail gas is shown in the following table 7:

TABLE 7 composition of chlorine-containing tail gas

Content/ingredient

Vinyl chloride

Water (W)

Carbon dioxide

Carbon monoxide

Methyl chloride

Nitrogen gas

Content before treatment (wt)

62％

1.8％

15％

6％

0.2％

15％

Content after treatment (wt)

30ppm

2％

83％

0

10ppm

15％

Example 5

(1) Preparing an active component doped precursor: controlling the fine niobium ore: hydrofluoric acid: the mass ratio of potassium fluoride was 1:5:0.8, and the other conditions were the same as in example 4.

(2) Preparing a doped active component: the same as in example 4.

(3) Preparing and modifying a carrier: the selection and the mass ratio of the silane coupling agent are 570: si-69 is 1:1, other conditions are the same as in example 4.

(4) Loading active components: the same as in example 4.

The effect of catalytic incineration tail gas is shown in the following table 8:

TABLE 8 composition of chlorine-containing tail gas

Content/ingredient

Vinyl chloride

Water (W)

Carbon dioxide

Carbon monoxide

Methyl chloride

Nitrogen gas

Content before treatment (wt)

62％

1.8％

15％

6％

0.2％

15％

Content after treatment (wt)

41ppm

2％

83％

0

16ppm

15％

Comparative example 1

(1) Preparing an active component doped precursor: 100g of MnO was added with hydrofluoric acid and potassium fluoride in the proportions described in example 3 to produce a precursor solution containing no Nb component.

(2) Preparing a doped active component: the same as in example 3.

(3) Preparing and modifying a carrier: the same as in example 3.

(4) Loading active components: the same as in example 3.

The catalytic incineration tail gas effect is shown in the following table 9 and is poorer than the effect of the embodiment 1-5 through evaluation of a small test device.

TABLE 9 composition of chlorine-containing off-gas

Content/ingredient

Vinyl chloride

Water (W)

Carbon dioxide

Carbon monoxide

Methyl chloride

Nitrogen gas

Content before treatment (wt)

62％

1.8％

15％

6％

0.2％

15％

Content after treatment (wt)

235ppm

2％

82.5％

2.4％

19ppm

13％

Comparative example 2

(1) Preparing an active component doped precursor: the same as in example 3.

(2) Preparing a doped active component: the same as in example 3.

(3) Preparing and modifying a carrier: in the comparative example, the carrier is a 4A molecular sieve of 200-300 meshes, and the other processes are the same as those in example 3.

(4) Loading active components: the same as in example 3.

The catalytic incineration tail gas effect is shown in the following table 10 and is poorer than the effect of the embodiment 1-5 through evaluation of a small test device.

TABLE 10 chlorine-containing tail gas composition

Content/ingredient

Vinyl chloride

Water (W)

Carbon dioxide

Carbon monoxide

Methyl chloride

Nitrogen gas

Content before treatment (wt)

62％

1.8％

15％

6％

0.2％

15％

Content after treatment (wt)

122ppm

2％

82.7％

1.2％

16ppm

14％

Comparative example 3

(1) Preparing an active component doped precursor: the same as in example 3.

(2) Preparing a doped active component: the same as in example 3.

(3) Preparing and modifying a carrier: the same as in example 3.

(4) Loading active components: the calcination process was not passivated by introducing air containing water vapor, and the other processes were the same as in example 3.

The catalytic incineration tail gas effect is shown in the following table 11 and is poorer than the effect of the examples 1-5 through evaluation of a small test device.

TABLE 11 composition of chlorine-containing tail gas

Content/ingredient

Vinyl chloride

Water (W)

Carbon dioxide

Carbon monoxide

Methyl chloride

Nitrogen gas

Content before treatment (wt)

62％

1.8％

15％

6％

0.2％

15％

Content after treatment (wt)

368ppm

2％

82.5％

2.2％

19ppm

13％

Comparative example 4

Referring to CN109107567A example 6, the preparation method of the catalyst adopts MnO as an active component and CuO and CeO₂As a dopant, the spherical 4A molecular sieve is used as a carrier, the supported CuO-MnO-CeO2 catalyst is prepared by referring to the process conditions (the molar ratio of Mn to Ce is 1:1, and the molar ratio of Cu to Ce is 1:1), and the tail gas in the invention is used for verifying the catalytic effect.

The effect of the catalytic incineration tail gas is shown in the following table 12 and is poorer than the effect of the catalytic incineration tail gas in the examples 1-5 according to the evaluation of a small test device:

TABLE 12 composition of chlorine-containing tail gas

Content/ingredient

Vinyl chloride

Water (I)

Carbon dioxide

Carbon monoxide

Methyl chloride

Nitrogen gas

Content before treatment (wt)

62％

1.8％

15％

6％

0.2％

15％

Content after treatment (wt)

13％

2％

69.9％

10ppm

16ppm

15％

It should be noted that the above examples are merely illustrative of representative embodiments of the present invention, and thus are preferred embodiments. And not to limit the scope of the invention, and although the invention has been described in detail with reference to preferred embodiments thereof, it will be understood by those skilled in the art that various changes and modifications may be made, and equivalents may be substituted for elements thereof without departing from the scope of the invention as defined in the claims.

Claims

1. A preparation method of a catalyst for catalyzing and burning vinyl chloride to polymerize wet tail gas is characterized by comprising the following steps:

(1) preparing an active component doped precursor: dissolving mineral containing metal niobium with acid, adding fluorine salt, fluorinating and complexing to generate doped precursor K₂[NbOF₅]；

(3) preparing and modifying a carrier: modifying the attapulgite with a modifier solution containing a silane coupling agent;

(4) loading active components: vacuum dipping the modified carrier with the active component emulsion, roasting and forming, passivating with steam, cooling;

the attapulgite for modification in the step (3) is a 200-300-mesh sieve component, and the modifier solution comprises ethanol, hydrofluoric acid, aluminum nitrate, magnesium nitrate and a silane coupling agent in a volume ratio of =4:1:2:2: 1; the ratio of the amount of the modifier solution to the attapulgite is (1-2) L:100 g.

2. The method for preparing the catalyst according to claim 1, wherein the metal-containing niobium mineral in the step (1) is refined niobium mineral, the acid is hydrofluoric acid, and the fluorine salt is potassium fluoride, wherein the mass ratio of the refined niobium mineral to the hydrofluoric acid to the potassium fluoride is 1 (3-5) to (0.8-1).

3. The method for preparing a catalyst according to claim 1, wherein the active component MnO of step (2) is mixed with the doped precursor K₂[NbOF₅]Mixing according to the weight ratio of (10-50) g to 300 g; adding excess NH₄Controlling the pH value of OH to be 8-10.

4. The preparation method of the catalyst according to claim 1, wherein the modification process in the step (3) is stirring for 30-60 min at 45-75 ℃, and drying at 90-110 ℃ after modification.

5. The method for preparing a catalyst according to claim 1, wherein the silane coupling agent in the step (3) is one or more of KH550, KH560, KH570, Si-69 and LM-N308.

6. The preparation method of the catalyst according to claim 1, wherein the ratio of the doped active component emulsion to the modified carrier is (200-300) mL:100g, and the soaking time is 5-8 h during the soaking in the step (4).

7. The preparation method of the catalyst according to claim 1, wherein the step (4) is calcined at 550-700 ℃ for 7-10 h, and air containing water vapor is introduced for passivation in the calcination stage, wherein the concentration of the water vapor is less than 800ppm based on the mass of the air containing the water vapor.

8. A catalyst for catalyzing and incinerating wet tail gas generated in vinyl chloride polymerization, which is prepared by the method for preparing the catalyst for catalyzing and incinerating wet tail gas generated in vinyl chloride polymerization according to any one of claims 1 to 7.