Cracking dechlorination catalyst as well as preparation method and application thereof

Abstract

The invention discloses a cracking dechlorination catalyst as well as a preparation method and application thereof. The cracking dechlorination catalyst comprises zeolite, an adsorbent and a carrier, the zeolite is selected from at least one of an MFI structure, an FAU structure and an MEL structure; the adsorbent is selected from at least one of metal oxide and carbonate; and the carrier is selected from one of a carbon material and carbide. The invention provides a catalyst for one-step catalytic cracking-dechlorination of waste plastics, which can realize oil recovery and chlorine impurity removal in one step in catalytic cracking of chlorine-containing waste plastics.

Description

TECHNICAL FIELD

[0001] The application relates to a cracking and dechlorination catalyst as well as a preparation method and application thereof, and belongs to the field of waste plastic recycling. BACKGROUND

[0002] In addition to the main components of polyethylene (PE) and polypropylene (PP), waste plastics also contain about 10-20% of chlorinated waste plastics such as polyvinyl chloride (PVC) and / or polyvinylidene chloride (PVDC). In the production of fuel oil by catalytic cracking of waste plastics, these chlorines will enter the product in the form of HCl or chlorinated organic matter, and the concentration is as high as several hundred to several thousand ppm. Therefore, such pyrolysis oil usually needs to be adsorbed by a refining process to remove impurities before it can be used as a high-value product fuel such as gasoline or diesel. Or by pretreating the waste plastics, removing the chlorinated impurities by solventization, and then entering the subsequent pyrolysis process, the introduction of chlorine impurities from the raw material is reduced.

[0003] According to the refining method of the related art, chlorine is removed by being converted into HCl through hydrogen treatment of waste plastic pyrolysis oil in the presence of a hydrogen treatment catalyst. However, due to the high chlorine content of waste plastic pyrolysis oil, excessive HCl is generated during the hydrogen treatment process, which causes problems such as equipment corrosion, abnormal reaction, and product performance degradation. SUMMARY

[0004] In order to prevent the above problems caused by chlorine and other impurities contained in waste plastics, the application proposes a waste plastic one-step catalytic cracking-dechlorination catalyst, which can realize oil recovery and chlorine impurity removal in one step in the catalytic cracking of chlorinated waste plastics.

[0005] The application aims to provide a waste plastic one-step catalytic cracking-dechlorination catalyst and a preparation method thereof, which can realize oil recovery and chlorine impurity removal in one step in the catalytic cracking of chlorinated waste plastics.

[0006] In one aspect of the application, a cracking and dechlorination catalyst is provided, which is composed of a zeolite-adsorbent-carrier three-part structure and can realize waste plastic one-step catalytic cracking-dechlorination.

[0007] The cracking and dechlorination catalyst comprises a zeolite, an adsorbent, and a carrier.

[0008] The zeolite is selected from at least one of MFI structure, FAU structure, and MEL structure.

[0009] The adsorbent is selected from at least one of a metal oxide and a carbonate.

[0010] The carrier is selected from one of a carbon material and a carbide.

[0011] Optionally, in the cracking dechlorination catalyst, the mass ratio of the zeolite, the adsorbent, and the carrier is 10-30%:30-60%:20-40%, and the sum of the mass ratio of the zeolite, the adsorbent, and the carrier is 100%.

[0012] Optionally, the zeolite is selected from at least one of ZSM-5, ZSM-11, ZSM-20, HY, USY, and SAPO-37.

[0013] Optionally, the metal oxide is selected from at least one of iron oxide, copper oxide, zinc oxide, calcium oxide, and magnesium oxide.

[0014] The carbonate is selected from at least one of calcium carbonate and magnesium carbonate.

[0015] Optionally, the carbon material is selected from at least one of graphene, carbon nanotube, graphite, carbon black, activated carbon, and substance A, wherein the substance A is a product obtained by carbonizing an organic matter.

[0016] The carbide is selected from at least one of silicon carbide, zirconium carbide, iron carbide, tungsten carbide, and molybdenum carbide.

[0017] Optionally, the organic matter is an organic macromolecular compound.

[0018] The organic macromolecular compound includes a synthetic macromolecular compound and a natural organic macromolecular compound.

[0019] Optionally, the natural organic macromolecular compound is at least one of starch and cellulose.

[0020] Optionally, the synthetic macromolecular compound is selected from at least one of epoxy resin, phenolic resin, polystyrene, styrene-divinylbenzene copolymer, polyacrylonitrile, and polyaniline.

[0021] Another aspect of the present application provides a preparation method of the cracking dechlorination catalyst, and the preparation method comprises:

[0022] S1, physically mixing an adsorbent precursor and a carrier precursor, calcining I, to obtain carrier-adsorbent composite particles;

[0023] S2, immersing the carrier-adsorbent composite particles obtained in S1 in a slurry containing a zeolite, and drying, to obtain a composite catalyst precursor;

[0024] S3, calcining II the composite catalyst precursor obtained in S2, to obtain the cracking dechlorination catalyst.

[0025] Optionally, the temperature of the calcining I is 400-600°C, and the time of the calcining I is 1-6h.

[0026] The calcination atmosphere used in the calcination I is at least one of nitrogen, argon, air.

[0027] Optionally, the temperature of the calcination I is independently selected from any value or a range between any two of 400℃, 450℃, 500℃, 550℃, 600℃.

[0028] Optionally, the time of the calcination I is independently selected from any value or a range between any two of 1h, 2h, 3h, 4h, 5h, 6h.

[0029] Optionally, the temperature of the drying is 100-130℃, and the time of the drying is 2-12h.

[0030] Optionally, the temperature of the drying is independently selected from any value or a range between any two of 100℃, 110℃, 120℃, 130℃.

[0031] Optionally, the time of the drying is independently selected from any value or a range between any two of 2h, 4h, 6h, 8h, 10h, 12h.

[0032] Optionally, the temperature of the calcination II is 500-700℃,

[0033] The time of the calcination II is 2-8h;

[0034] The calcination atmosphere used in the calcination II is at least one of nitrogen, argon, air.

[0035] Optionally, the temperature of the calcination II is independently selected from any value or a range between any two of 500℃, 550℃, 600℃, 650℃, 700℃.

[0036] Optionally, the time of the calcination II is independently selected from any value or a range between any two of 2h, 4h, 6h, 8h.

[0037] As a specific embodiment, a preparation method of a catalyst for waste plastic one-step catalytic cracking-dechlorination includes the following steps:

[0038] S1: Preparation of carrier-adsorbent composite material: a certain amount of adsorbent and carrier or carrier precursor are physically mixed, deionized water is added, kneaded and granulated, and then calcined at 400-600℃ for 1-6h in a certain atmosphere to obtain carrier-adsorbent composite particles.

[0039] S2: Preparation of the composite catalyst: a certain amount of zeolite powder is mixed with deionized water to form a slurry, the granular composite material obtained in step S1 is immersed in the slurry, and then dried at 100-130°C for 2-12h to obtain a composite catalyst precursor.

[0040] S3: The composite catalyst precursor obtained in S2 is calcined at 500-700°C under a certain atmosphere for 2-8h to obtain a composite catalyst.

[0041] In another aspect of the present application, the application provides an application of the above-mentioned cracking and dechlorination catalyst in a catalytic cracking reaction of waste plastics,

[0042] The temperature of the catalytic cracking reaction is 400-600°C.

[0043] The waste plastics are polyolefin-based waste plastics.

[0044] The chlorine content in the waste plastics is ≤4000ppm.

[0045] The mass ratio of the cracking and dechlorination catalyst to the waste plastics is 1:1-1:50.

[0046] In the catalytic cracking reaction, the conversion rate is greater than 99%, the liquid hydrocarbon yield is greater than 80%, and the removal rate of chlorine is greater than 97%.

[0047] The beneficial effects that can be produced by the present application include:

[0048] 1) The cracking and dechlorination catalyst provided by the present application has excellent catalytic performance and dechlorination efficiency.

[0049] 2) The cracking and dechlorination catalyst provided by the present application has the effect of realizing oil recovery and chlorine impurity removal in one step, reducing the reaction process, and reducing costs.

[0050] 3) The cracking and dechlorination catalyst provided by the present application can effectively prevent the conversion of chlorine elements into hydrogen chloride during the plastic cracking process, reducing the corrosion of the pipeline. DETAILED DESCRIPTION

[0051] The present application will be described in detail below in conjunction with examples, but the present application is not limited to these examples.

[0052] Unless otherwise specified, the raw materials in the examples of the present application are purchased through commercial channels.

[0053] The analysis method in the examples of the present application is as follows:

[0054] A gas chromatography quadrupole time-of-flight high-resolution mass spectrometer is used for qualitative analysis of liquid components.

[0055] A gas chromatography is used for quantitative analysis of liquid components.

[0056] Analysis of residual Cl element in liquid components by inductively coupled plasma tandem mass spectrometry.

[0057] The conversion rate ω, liquid hydrocarbon yield μ, alkane, olefin, aromatic hydrocarbon content α, β, γ, and Cl removal rate θ in the embodiments of the present application are calculated as follows:

[0058]

[0059] wherein ω represents the reaction conversion rate, m0 represents the mass of the initially added reactant waste plastic, and m1 represents the mass remaining in the reactor after the reaction ends.

[0060]

[0061] wherein μ represents the reaction liquid hydrocarbon yield, m0 represents the mass of the initially added reactant waste plastic, and m2 represents the mass of the collected liquid product after the reaction ends.

[0062]

[0063] wherein α represents the total alkane content in the liquid hydrocarbons, and αi represents the percentage of alkanes with carbon number i in the liquid hydrocarbons. i

[0064]

[0065] wherein β represents the total olefin content in the liquid hydrocarbons, and βi represents the percentage of olefins with carbon number i in the liquid hydrocarbons. i

[0066]

[0067] wherein γ represents the total aromatic hydrocarbon content in the liquid hydrocarbons,

[0068]

[0069] wherein θ represents the removal rate of Cl element before and after the reaction, m3 represents the mass of the initial Cl element, and m4 represents the mass of the residual Cl element detected after the reaction ends.

[0070] Example 1: Preparation of ZSM-5 / CaCO3-C catalyst

[0071] The process for preparing ZSM-5 / CaCO3-C (C from organic synthetic polymer phenolic resin) in this example is as follows: ​​​​​

[0072] S1: 50 g of calcium carbonate and 50 g of phenolic resin are mechanically mixed, 15 g of water is added during the mixing process, and then granulation is performed by mechanical kneading. The preliminary mixed material is calcined at 500°C for 5 h in a nitrogen atmosphere. During the calcination process, the phenolic resin is completely converted into carbon, which imparts good mechanical strength and water resistance to the adsorbent, and a CaCO3-C with a CaCO3:C mass ratio of 50:30 is prepared.

[0073] S2: 30 g of ZSM-5 powder and 100 g of deionized water are mixed to form a slurry by ultrasonic dispersion. The CaCO3-C prepared in step 1 is impregnated therein, and dried at 120°C for 12 h. The impregnation and drying are repeated until the impregnation ratio reaches 20%, and a ZSM-5 / CaCO3-C composite material is obtained.

[0074] S3: The composite material prepared in step S2 is calcined at 550°C in a nitrogen atmosphere for 6 h, and a composite catalyst ZSM-5 / CaCO3-C with a ZSM-5:CaCO3:C ratio of 20:50:30 is obtained.

[0075] Example 2: Preparation of HY / MgO-C catalyst

[0076] The process for preparing HY / MgO-C (C from natural high molecular substance starch) in this example is as follows:

[0077] S1: 50 g of MgO and 50 g of starch are mechanically mixed, 15 g of water is added during the mixing process, and then granulation is performed by mechanical kneading. The preliminary mixed material is calcined at 450°C for 4 h in a nitrogen atmosphere. During the calcination process, the starch is converted into carbon, which imparts good mechanical strength and water resistance to the adsorbent, and a MgO-C with a MgO:C mass ratio of 50:20 is prepared.

[0078] S2: 30 g of HY powder and 100 g of deionized water are mixed to form a slurry by ultrasonic dispersion. The MgO-C prepared in step 1 is impregnated therein, and dried at 110°C for 12 h. The impregnation and drying are repeated until the impregnation ratio reaches 30%, and a composite material is obtained.

[0079] S3: The composite material prepared in step 2 is calcined at 550°C in an inert atmosphere for 6 h, and a composite catalyst HY / MgO-C with a HY:MgO:C ratio of 30:50:20 is obtained.

[0080] Example 3: Preparation of ZSM-11 / MgCO3-C catalyst

[0081] The process for preparing ZSM-11 / MgCO3-C (C from graphene) in this example is as follows:

[0082] S1: 50 g of MgCC and 30 g of graphene are mechanically mixed, 15 g of water is added during the mixing process, then granulated by mechanical kneading, and the preliminary mixed material is calcined at 500°C for 5 h in a nitrogen atmosphere. During the calcination process, the starch is completely converted into carbon, which gives the adsorbent good mechanical strength and water resistance. A MgCC-C with a mass ratio of MgCC:C of 50:30 is prepared.

[0083] S2: 30 g of ZSM-11 powder and 100 g of deionized water are mixed to form a slurry, and the MgCC-C prepared in step 1 is impregnated therein and dried at 120°C for 12 h. The impregnation and drying are repeated until the impregnation ratio reaches 20%, and a composite material is obtained.

[0084] S3: The composite material prepared in step 2 is calcined at 550°C in an inert atmosphere for 6 h to obtain a composite catalyst ZSM-11 / MgCC-C with a ZSM-11:MgCC:C ratio of 20:50:30.

[0085] Example 4: Preparation of ZSM-5 / CaCC-SiC catalyst

[0086] The process for preparing ZSM-5 / CaCC-SiC in this example is as follows:

[0087] S1: 50 g of calcium carbonate and 40 g of silicon carbide are mechanically mixed, 15 g of water is added during the mixing process, then granulated by mechanical kneading, and the preliminary mixed material is calcined at 500°C for 5 h in a nitrogen atmosphere to prepare CaCC-SiC with a mass ratio of CaCC:SiC of 50:40.

[0088] S2: 30 g of ZSM-5 powder and 100 g of deionized water are mixed to form a slurry, and the CaCC-SiC prepared in step 1 is impregnated therein and dried at 120°C for 12 h. The impregnation and drying are repeated until the impregnation ratio reaches 10%, and a composite material is obtained.

[0089] S3: The composite material prepared in step 2 is calcined at 550°C in an inert atmosphere for 6 h to obtain a composite catalyst ZSM-5 / CaCC-SiC with a ZSM-5:CaCC:SiC ratio of 10:50:40.

[0090] Comparative Example 1:

[0091] The process for preparing the catalyst in Comparative Example 1 is basically the same as in Example 1, except that step S1 is omitted and ZSM-5 slurry is directly impregnated with CaCC to prepare ZSM-5 / CaCC.

[0092] Comparative Example 2:

[0093] The process for preparing the catalyst of Comparative Example 2 is basically the same as that of Example 1, except that steps S2 and S3 are omitted, and CaCO3-C is prepared.

[0094] Comparative Example 3:

[0095] The process for preparing the catalyst of Comparative Example 3 is basically the same as that of Example 1, except that 100 g of phenolic resin is directly carbonized to prepare C in step S1.

[0096] Comparative Example 4:

[0097] The process for preparing the catalyst of Comparative Example 4 is basically the same as that of Example 1, except that the calcination temperatures of S1 and S3 are adjusted to 600°C and 400°C, respectively, and ZSM-5 / CaCO3-C-T is prepared.

[0098] Comparative Example 5:

[0099] The process for preparing the catalyst of Comparative Example 5 is basically the same as that of Example 1, except that the impregnation time and drying temperature of S2 are adjusted to 1 h and 80°C, respectively, and ZSM-5 / CaCO3-C is prepared.

[0100] Comparative Example 6:

[0101] The process for preparing Hβ / MgO-C (C from cellulose carbonization) in this example is as follows:

[0102] S1. 50 g of MgO and 30 g of cellulose are mechanically mixed, 15 g of water is added during the mixing process, and then granulated by mechanical kneading. The preliminary mixed material is calcined at 500°C for 5 h in a nitrogen atmosphere to prepare MgO-C.

[0103] S2. 30 g of Hβ powder and 100 g of deionized water are mixed to form a slurry by ultrasonic dispersion. The MgO-C prepared in step 1 is immersed therein and dried at 120°C for 12 h. The immersion and drying are repeated until the impregnation ratio reaches 20%, and the composite material is obtained.

[0104] S3. The composite material prepared in step S2 is calcined at 550°C for 6 h in an inert atmosphere to obtain the composite catalyst.

[0105] Example 5: Catalytic cracking of waste plastics

[0106] The materials prepared in Examples 1-4 and Comparative Examples 1-6 are applied to the catalytic cracking reaction of waste plastics (the main components of which are PE accounting for 50% and PP accounting for 50%, and the chlorine content is 3000 ppm), and the process is as follows:

[0107] The waste plastic catalytic cracking was carried out in a two-stage tubular furnace. First, a certain amount of quartz wool was added to both stages of the quartz tube, 1 g of waste plastic was added to the front end, 50 mg of catalyst was added to the rear end, nitrogen was introduced to replace the gas in the tube, and the inert atmosphere was maintained, the front end was heated to 450℃ at a rate of 5℃ / min, and maintained for 2h, the rear end of the quartz tube was also heated to 300℃ at a rate of 5℃ / min, and maintained for 4h, the tail was connected with a cooler, a collection bottle and a gas bag were used to collect the reaction cooled liquid and non-condensable gas, after the reaction was completed, part of the liquid was used to analyze its elemental composition, part was added into dichloromethane as a solvent, and uniformly mixed, and used for chromatographic analysis.

[0108] The catalyst was applied to the waste plastic catalytic cracking reaction, and the reaction data is shown in Table 1.

[0109] Table 1 Waste plastic cracking reaction data in Example 5

[0110]

[0111] Example 6:

[0112] The materials prepared in Examples 1-4 and Comparative Examples 1-6 were applied to the waste plastic catalytic cracking reaction, and the process was the same as Example 5.

[0113] The catalyst was applied to the waste plastic catalytic cracking reaction, and the reaction data is shown in Table 2.

[0114] Table 2 Reaction data in Example 6

[0115]

[0116]

[0117] The above is only a few embodiments of the present application, and does not limit the present application in any form. Although the above preferred embodiments are disclosed, they are not intended to limit the present application. Any skilled person in the art can make some changes or modifications to the above disclosed technical content without departing from the scope of the technical solution of the present application, which are equivalent to equivalent embodiments, and are within the scope of the technical solution.

Claims

1. A cracking and dechlorination catalyst, characterized in that, the cracking and dechlorination catalyst comprises a zeolite, an adsorbent, a carrier; the zeolite is selected from at least one of MFI structure, FAU structure, and MEL structure; the adsorbent is selected from at least one of metal oxides and carbonates; the carrier is selected from one of carbon materials and carbides.

2. The cracking and dechlorination catalyst according to claim 1, characterized in that, in the cracking and dechlorination catalyst, the mass ratio of the zeolite, the adsorbent, and the carrier is 10-30%:30-60%:20-40%, and the sum of the mass ratio of the zeolite, the adsorbent, and the carrier is 100%.

3. The cracking and dechlorination catalyst according to claim 1, characterized in that, the zeolite is selected from at least one of ZSM-5, ZSM-11, ZSM-20, HY, USY, and SAPO-37; preferably, the metal oxide is selected from at least one of iron oxide, copper oxide, zinc oxide, calcium oxide, and magnesium oxide; the carbonate is selected from at least one of calcium carbonate and magnesium carbonate.

4. The cracking and dechlorination catalyst according to claim 1, characterized in that, the carbon material is selected from at least one of graphene, carbon nanotube, graphite, carbon black, activated carbon, and substance A, wherein the substance A is a product obtained by carbonizing an organic matter; the carbide is selected from at least one of silicon carbide, zirconium carbide, iron carbide, tungsten carbide, and molybdenum carbide.

5. The cracking and dechlorination catalyst according to claim 4, characterized in that, the organic matter is an organic polymer compound; the organic polymer compound comprises a synthetic polymer compound and a natural organic polymer compound; preferably, the natural organic polymer compound is at least one of starch and cellulose; preferably, the synthetic polymer compound is selected from at least one of epoxy resin, phenol formaldehyde resin, polystyrene, styrene-divinylbenzene copolymer, polyacrylonitrile, and polyaniline.

6. A process for the preparation of the cleavage dechlorination catalyst according to any one of claims 1 to 5, characterized in that the preparation method comprises: S1, physically mixing an adsorbent and a carrier precursor, calcining I, to obtain carrier-adsorbent composite particles; S2, immersing the carrier-adsorbent composite particles obtained in S1 in a slurry containing a zeolite, drying, to obtain a composite catalyst precursor; S3, calcining II of the composite catalyst precursor obtained in S2, to obtain the cracking and dechlorination catalyst.

7. The preparation method according to claim 6, characterized in that, the calcining I is at a temperature of 400-600°C, and the calcining I is for 1-6h; the calcining I uses at least one of nitrogen, argon, and air as a calcining atmosphere.

8. The preparation method according to claim 6, characterized in that, the drying is at a temperature of 100-130°C, and the drying is for 2-12h.

9. The preparation method according to claim 6, characterized in that, the calcining II is at a temperature of 500-700°C, the calcining II is for 2-8h; the calcining II uses at least one of nitrogen, argon, and air as a calcining atmosphere.

10. Use of the cracking and dechlorination catalyst according to any one of claims 1-5 in a catalytic cracking reaction of waste plastics, characterized in that, The temperature of the catalytic cracking reaction is 400-600 DEG C; The waste plastic is polyolefin waste plastic; The chlorine content in the waste plastic is less than or equal to 4000 ppm; The mass ratio of the cracking dechlorination catalyst to the waste plastic is 1:1-1:50.

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