A hydrogen-type lignin recombinant multi-stage molecular sieve catalyst and its preparation and application

Abstract

The present invention relates to the technical field of resource utilization of mulch film catalytic cracking, and more specifically to a hydrogen-type lignin recombinant multi-stage molecular sieve catalyst and its preparation and application. By using lignin as an organic template to assist in the reassembly of Y molecular sieves, the aluminosilicate fragments are re-deposited as a mesoporous phase, and a larger pore structure connected to the inherent microporous channels is introduced, a multi-level pore system is formed, which improves the diffusion rate of waste mulch film raw materials and coke precursors in the catalyst, greatly improves the catalytic cracking efficiency, and solves the problems of severe coke deposition and short life of traditional Y molecular sieve catalysts. The hydrogen-type lignin recombinant multi-stage molecular sieve catalyst has excellent selectivity for waste mulch film cracking products, which is beneficial to the catalytic cracking of waste mulch films to form synthesis gas and natural gas. Synthesis gas and natural gas are important raw materials in the processing of chemical fuels, and have good economic and environmental benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of resource utilization of ground film catalytic cracking, and more specifically to a hydrogen-type lignin recombinant multi-stage molecular sieve catalyst and its preparation and application. Background Art

[0002] Plastic mulch is an important auxiliary material for agricultural production in arid areas. It has the functions of heat preservation and moisture retention, weed suppression, ground temperature increase, and yield increase. It is widely used in the arid northwest and cold northeast regions. As a major agricultural producer, my country uses a very high amount of mulch. If a large amount of mulch is not recycled in time after use, it will remain in the soil and be difficult to degrade, which will cause a series of pollution to the environment. Therefore, it is necessary to regularly recycle and reuse the waste mulch. The traditional recycling and reuse method is to manually collect and pack the mulch and transport it to the power plant for combustion and power generation. This treatment method causes the mulch to produce a large amount of harmful gases during the combustion process, which causes serious pollution to the environment. In addition, some mulch recycling methods use traditional cracking devices to oil or gasify waste mulch, but the oil and gas production of the process is low, and the oil and gas production types are more, the selectivity is low, and the cracking efficiency is not high. Therefore, how to efficiently catalyze and crack the waste mulch for resource utilization has become a key problem that needs to be solved. Introducing catalysts in the cracking process is a common solution.

[0003] Y molecular sieve is a catalyst with unique twelve-membered ring channels and rich acidic centers. Due to its high catalytic cracking activity and strong acid resistance, it is widely used in various industries. For example, in previous studies, modified Y molecular sieves were applied to the catalytic cracking process of plastics. The Y molecular sieve has the characteristics of good cracking performance and strong isomerization ability. However, the internal channels of Y molecular sieve are small and narrow, which is not conducive to the diffusion of macromolecular reactants and products during catalytic cracking, and is easy to form serious coke byproducts, which reduces the life and catalytic efficiency of the catalyst. Summary of the invention

[0004] To this end, it is necessary to provide a hydrogen-type lignin recombinant multi-stage molecular sieve catalyst and its preparation and application to solve the technical problems of low oil and gas production in the traditional waste film cracking process, a large number of oil and gas types, low selectivity and low cracking efficiency.

[0005] To achieve the above object, in a first aspect of the present invention, the inventor provides a method for preparing a hydrogen-type lignin recombinant multi-stage molecular sieve catalyst, comprising the following steps:

[0006] Preparation of aluminosilicate fragments: uniformly mixing a Y-type molecular sieve and a sodium hydroxide solution, stirring at 70° C. to 80° C. for 1 h to 2 h in a condensation reflux device, wherein Si / Al in the Y-type molecular sieve is 5, to obtain an aluminosilicate fragment solution;

[0007] Emulsified lignin: emulsify lignin with an emulsifier formed by ethyl acetate and deionized water in a volume ratio of 2:8 to obtain an emulsified lignin solution;

[0008] Preparing a precursor: uniformly mixing the emulsified lignin solution and the aluminosilicate fragment solution, adjusting the pH value to 8.5-9.5, and placing the mixture in a high-pressure reactor at 160° C. to 200° C. for hydrothermal recrystallization, cooling, solid-liquid separation, and drying, placing the obtained solid in an ammonium salt solution for ion exchange, and removing water to obtain a hydrogen-type lignin recombinant multi-stage molecular sieve catalyst precursor;

[0009] Activation: The hydrogen-type lignin recombinant multi-stage molecular sieve catalyst precursor and the alkali activator are uniformly mixed at a mass ratio of 5 to 6:1, and calcined for activation to obtain the hydrogen-type lignin recombinant multi-stage molecular sieve catalyst.

[0010] The lignin applicable to the present invention includes lignin extracted from any one or a combination of at least two plants such as green bamboo, moso bamboo, birch, oak, Achnatherum splendens, wheat straw, ash, reed, poplar, masson pine, eucalyptus, bagasse, king bamboo grass, rice straw, mushroom grass, corn cob, etc.

[0011] The ion exchange of the present invention is carried out at 90° C. for 4 hours, preferably repeated twice.

[0012] In the step of preparing the precursor of the present invention, a sodium hydroxide solution with a mass fraction of 10% is used to adjust the pH value.

[0013] As a preferred embodiment of the present invention, the calcination temperature in the activation step is 450° C. to 600° C., and the calcination time is 3 h to 6 h.

[0014] As a preferred embodiment of the present invention, in the step of emulsifying lignin, the ethyl acetate and deionized water are used to form an emulsifier and lignin at a mass ratio of 18 to 19.8:1 and stirred and mixed at a rotation speed of 300 rpm to 800 rpm.

[0015] As a preferred embodiment of the present invention, the ammonium salt solution is an ammonium nitrate solution with a mass fraction of 8%-10%, and the ammonium salt solution is selected from at least one of ammonium nitrate, carbonate, acetate, phosphate or acid salt. If there are more than one, it is a mixture of any two or more of ammonium nitrate, carbonate, acetate, phosphate or acid salt in any mass percentage.

[0016] As a preferred embodiment of the present invention, the alkali activator is selected from at least one of potassium hydroxide, magnesium hydroxide, lithium hydroxide, calcium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate and sodium bicarbonate.

[0017] As a preferred embodiment of the present invention, the solid-liquid separation in the step of preparing the precursor is carried out by centrifugation with a rotation speed of 6000-7000 rpm.

[0018] As a preferred embodiment of the present invention, the mass ratio of the Y-type molecular sieve to lignin is 2 to 4:1.

[0019] In the second aspect of the present invention, the inventor provides a hydrogen-type lignin recombinant multi-stage molecular sieve catalyst, which is prepared by the preparation method described in the first aspect of the present invention.

[0020] As a preferred embodiment, the hydrogen-type lignin recombinant multi-stage molecular sieve catalyst contains, by mass percentage: 3% to 7.5% lignin, 12% to 15% Y-type molecular sieve, 12% to 22% ammonium salt, and 10% to 15% ethyl acetate. Such a ratio can maximize the use of lignin as an organic template to assist in reassembly, redeposit the aluminosilicate fragments into a mesoporous phase, introduce a larger pore structure connected to the inherent microporous channels, and form a hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst with a multi-level pore system.

[0021] In the third aspect of the present invention, the inventor provides an application of the hydrogen-type lignin recombinant multi-stage molecular sieve catalyst provided in the second aspect of the present invention in catalytic cracking of waste polyethylene membranes, comprising the following steps:

[0022] Pretreatment of waste polyethylene film: washing, grinding, drying and sieving the waste polyethylene film to obtain film fragments with an average particle size of less than 2 mm to be treated, wherein the drying is performed at 60° C. for 12 hours to remove excess moisture;

[0023] In-situ catalytic cracking: the membrane fragments to be treated and the hydrogen-type lignin recombinant multi-stage molecular sieve catalyst are placed in a cracking reactor at a mass ratio of (1-2):4, wherein the membrane fragments to be treated and the hydrogen-type lignin recombinant multi-stage molecular sieve catalyst are separated by thin quartz wool for in-situ catalytic cracking, the cracking temperature is 720℃~800℃, and nitrogen is filled at a flow rate of 80mL / min~120mL / min before opening the cracking reactor to obtain anaerobic conditions, the cracking reaction time is 15min~20min, and the nitrogen flow rate during the cracking reaction is <25 mL / min as a carrier gas. At the end of the reaction, the non-condensable gas is collected with an air bag, and the collected gaseous products are the synthesis gas and natural gas.

[0024] The hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst provided by the present invention is used for in-situ cracking of waste polyethylene films including (but not limited to) waste ground films, thereby improving the diffusion rate of waste ground film raw materials and coke precursors in the catalyst, thereby improving the catalytic cracking efficiency of the ground film, solving the problem of severe coke deposition in traditional Y molecular sieve catalysts, and greatly improving the selectivity of ground film cracking products.

[0025] Preferably, the feed ratio of the hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and the pretreated ground film is (1-2):4, the reactor temperature is set to 720℃~800℃, and nitrogen is filled at a flow rate of 80-120 mL / min for a period of time before cracking to obtain anaerobic cracking conditions. Each cracking operation is completed within 20 minutes, and the nitrogen flow rate is maintained at a low flow rate (<25 mL / min) as a carrier gas during the cracking process. Such cracking reaction conditions have high heating efficiency, energy utilization rate and cracking conversion efficiency, and can maximize the cracking of waste ground film into raw materials for chemical fuels such as synthesis gas and natural gas at the lowest cost, and well realize the directional catalytic cracking conversion of organic components in the ground film.

[0026] Different from the prior art, the above technical solution has the following beneficial effects:

[0027] The present invention provides a method for preparing a hydrogen-type lignin recombinant multi-stage molecular sieve catalyst, in which lignin is used as an organic template to assist in the reassembly of Y molecular sieves, aluminosilicate fragments are redeposited as a mesoporous phase, and a larger pore structure connected to inherent microporous channels is introduced to form a multi-level pore system, thereby increasing the diffusion rate of waste mulch materials and coke precursors in the catalyst, greatly improving the catalytic cracking efficiency, and solving the problems of severe coke deposition and short life of traditional Y molecular sieve catalysts.

[0028] The hydrogen-type lignin recombinant multi-stage molecular sieve catalyst provided by the present invention has excellent selectivity for waste mulch film cracking products, which is beneficial to catalytic cracking of waste mulch film to form synthesis gas and natural gas. Synthesis gas and natural gas are both important raw materials in the chemical fuel processing process and have good economic and environmental benefits.

[0029] The present invention uses a simple reactor to in-situ catalytically crack the mulch film. The in-situ catalytic cracking can obtain better catalytic performance. The catalyst and the mixture are separated by thin quartz wool and placed in a cracking reactor, which reduces the cost and improves the heating efficiency. It solves the problem of high cracking treatment cost caused by the need for additional heating facilities to supply heat to the separated heating areas in the traditional in-situ catalytic cracking process, promotes the process of large-scale catalytic cracking industrial application of waste mulch film, and greatly improves the directional catalytic cracking conversion of organic components.

[0030] In summary, the present invention uses an alkaline Y molecular sieve solution as an aluminosilicate source and recombines with lignin to synthesize a hydrogen-type lignin recombinant multi-stage molecular sieve catalyst, and applies it to the catalytic cracking of waste mulch. After the in-situ catalytic cracking reaction in the cracking reactor, the total yield of synthesis gas and natural gas can reach 94.9wt%. In addition, the hydrogen-type lignin recombinant multi-stage molecular sieve catalyst has high catalytic cracking efficiency, no carbon deposition, and long life. It can be applied to the process of catalytic cracking and recovering synthesis gas and natural gas from waste polyethylene film products such as waste mulch, and has the characteristics of low cost, green environmental protection, and high conversion efficiency. It can greatly broaden the way of resource utilization of waste polyethylene film products such as waste mulch after recycling, meet the environmental protection regeneration needs of resource recycling, and have very important economic benefits, social benefits, and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 This is a SEM image of a hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst provided in a specific embodiment of the present invention;

[0032] Figure 2 A schematic diagram of the effect of catalytic cracking of mulch film using the hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst provided by a specific embodiment of the present invention;

[0033] Figure 3 This is the SEM image of the conventional Y molecular sieve catalyst without lignin reorganization;

[0034] Figure 4 Schematic diagram of coke deposition produced by cracking ground film using conventional Y molecular sieve without lignin reorganization. DETAILED DESCRIPTION

[0035] In order to explain the technical content, structural features, achieved objectives and effects of the technical solution in detail, the following is a detailed description in conjunction with specific embodiments and accompanying drawings.

[0036] Reference to "embodiment" herein means that the specific features, structures or characteristics described in conjunction with the embodiment may be included in at least one embodiment of the present application. The term "embodiment" appearing in various places in the specification does not necessarily refer to the same embodiment, nor does it particularly limit its independence or association with other embodiments. In principle, in the present application, as long as there is no technical contradiction or conflict, the various technical features mentioned in the embodiments can be combined in any way to form a corresponding implementable technical solution.

[0037] Unless otherwise defined, the technical terms used in this document have the same meanings as those generally understood by those skilled in the art to which this application belongs; the use of relevant terms in this document is only for describing specific embodiments and is not intended to limit this application.

[0038] In the description of this application, the term "and / or" is an expression used to describe the logical relationship between objects, indicating that three relationships may exist, for example, A and / or B, which means: A exists, B exists, and A and B exist at the same time. In addition, the character " / " in this article generally indicates that the objects before and after are in an "or" logical relationship.

[0039] In the present application, terms such as “first” and “second” are merely used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship of quantity, priority or sequence between these entities or operations.

[0040] Without further limitations, in this application, the words "include", "comprises", "has" or other similar expressions used in the sentences are intended to cover non-exclusive inclusion. These expressions do not exclude the presence of additional elements in the process, method or product including the elements, so that the process, method or product including a series of elements may include not only those limited elements, but also other elements not explicitly listed, or also include elements inherent to such process, method or product.

[0041] Similar to the understanding in the Examination Guidelines, in this application, expressions such as "greater than", "less than", "exceed" and the like are understood to exclude the number itself; expressions such as "above", "below", "within" and the like are understood to include the number itself. In addition, in the description of the embodiments of this application, "multiple" means more than two (including two), and similar expressions related to "multiple" are also understood in this way, such as "multiple groups", "multiple times", etc., unless otherwise clearly and specifically limited.

[0042] In the description of the embodiments of the present application, space-related expressions used, such as "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "vertical", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicate the orientation or position relationship based on the orientation or position relationship shown in the specific embodiments or drawings, and are only for the convenience of describing the specific embodiments of the present application or facilitating the reader's understanding, and do not indicate or imply that the referred device or component must have a specific position, a specific orientation, or be constructed or operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present application.

[0043] Unless otherwise expressly specified or limited, in the description of the embodiments of the present application, the terms such as "install", "connect", "connect", "fix", "set", etc. used should be understood in a broad sense. For example, the "connection" can be a fixed connection, a detachable connection, or an integrated setting; it can be a mechanical connection, an electrical connection, or a communication connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium; it can be the internal connection of two elements or the interaction relationship between two elements. For technicians in the technical field to which the present application belongs, the specific meanings of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0044] Y molecular sieve or modified Y molecular sieve is a commonly used catalytic cracking agent for waste plastics in the prior art. Although it has the characteristics of good cracking performance and strong isomerization ability, the internal pores of Y molecular sieve are small and narrow, which is not conducive to the diffusion of macromolecular reactants and products during catalytic cracking. It is easy to form serious coke byproducts, block the pores, and reduce the life and catalytic efficiency of the catalyst. In terms of improving the pore structure of Y molecular sieve, the inventor has done a lot of exploration, including optimizing the pore structure of Y molecular sieve using organic templates. Biomass-derived materials, as an organic template, have the potential to form new pore structures in Y molecular sieve catalysts to improve their catalyst performance. Lignin is the most widely distributed and largest aromatic biomacromolecule in the plant kingdom, with many advantages such as high carbon content, good biodegradability, biocompatibility and environmental friendliness. The inventor tried to use it as an organic soft template, expecting it to form a new mesoporous structure in the Y molecular sieve catalyst, promote the reactants to enter the catalyst active site, and then improve the catalytic efficiency of the Y molecular sieve catalyst. Based on this, the lignin recombinant Y molecular sieve was continuously tested, studied and adjusted to form the present invention.

[0045] The drug-related information used in the embodiments of the present invention is as follows:

[0046] Y-type zeolite powder (Y molecular sieve, Si / Al=5), sodium hydroxide, potassium hydroxide, ethyl acetate, ammonium salt, etc. are all commercially available and can be prepared according to the concentration required by the actual test.

[0047] The lignin used in the embodiments of the present invention is extracted from green bamboo, eucalyptus and masson pine, but this is only used to illustrate the technical solution of the present invention and is not used to limit the source of lignin. Lignin extracted from other plants can be used in the present invention.

[0048] The stirring equipment, drying equipment, dripping equipment, water bath equipment, SEM, micro gas chromatography system, thermal conductivity detector, etc. involved in the preparation method in the embodiment of the present invention are all commonly used equipment for experiments, as well as a pyrolysis reactor commonly used for mulch film pyrolysis.

[0049] The mulch used in the experiment was agricultural polyethylene mulch, which was uniformly collected and broken into small pieces for subsequent cracking.

[0050] The materials used in the embodiments of the present invention, when the sum of the mass percentages is 100%, the dosage of each material is: Y molecular sieve 8.0% to 10.0%, lignin 2.0% to 5.0%, sodium hydroxide 0.5% to 1.5%, ammonium salt 8.0% to 15.0%, alkali activator 2.0% to 3.0%, ethyl acetate 7.2% to 7.9%, water 28.8% to 31.6%, and ground film 30.0% to 40.0%.

[0051] The present invention adopts the method of weighing the solid residue of the ground film raw material and the mass of the catalyst added before and after each test run to determine the mass of the generated coke. The yields of liquid oil and coke are calculated by dividing the mass of the obtained liquid oil and coke by the mass of the initial ground film raw material, that is, liquid oil yield (%) = liquid oil mass / ground film raw material mass; coke yield (%) = coke mass / ground film raw material mass; the yield of the obtained gas product is: gas yield (%) = 1-liquid oil yield-coke yield. The content of synthesis gas and natural gas in the gas product is tested by a micro gas chromatography system and a thermal conductivity detector. Embodiment 1

[0052] This embodiment provides a hydrogen-type lignin recombinant multi-stage molecular sieve catalyst and a preparation and application method thereof, comprising the following specific steps:

[0053] 1. Raw materials and dosage

[0054] Y molecular sieve: 8.0kg;

[0055] Lignin (extracted from green bamboo): 2.0kg;

[0056] Sodium hydroxide (10%): 0.5kg;

[0057] Ammonium nitrate (10%): 8.0 kg;

[0058] Potassium hydroxide: 2.0kg;

[0059] Ethyl acetate: 7.9 kg;

[0060] Water: 31.6kg;

[0061] Ground film: 40.0kg.

[0062] 2. Process steps and parameters for preparing hydrogen-type lignin recombinant multi-stage molecular sieve catalyst

[0063] (1) Synthesis of hydrogen-type lignin recombinant multi-stage molecular sieve catalyst

[0064] 8.0 kg of Y-type zeolite powder was uniformly mixed with 0.45 kg of 10% sodium hydroxide solution by mass, and stirred at 70 ° C for 2 h in a condensation reflux device to obtain the aluminosilicate fragments required for the subsequent process. 2.0 kg of green bamboo lignin was emulsified with 39.5 kg of ethyl acetate and water with a volume ratio of 2:8, and added to the aluminosilicate fragments treated with 10% sodium hydroxide alkaline solution by mass fraction. The zeolite-derived components in the green bamboo lignin solution were fully dispersed by stirring at 800 rpm, and the pH value was adjusted to 8.5 with 0.05 kg of sodium hydroxide solution. The product was hydrothermally recrystallized in a high-pressure reactor at 0°C, and the cooled slurry was centrifuged at 6500 rpm for 15 min and dried at 105°C for 6 h, and then sodium ion exchange was performed in 8.0 kg of 10% ammonium nitrate solution by mass fraction. After filtering to remove excess water, the hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst precursor was uniformly mixed with 2.0 kg of potassium hydroxide and calcined at 450°C for 6 h for activation to obtain a hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst, wherein the sodium ion exchange was reacted at 90°C for 4 h, repeated twice and dried to constant weight to obtain the following Figure 1 The hydrogen-type lignin recombinant multi-stage molecular sieve catalyst of this embodiment is shown. The total surface area of ​​the catalyst calculated by the BET method is 380.1 m 2 / g.

[0065] (2) Pretreatment of waste mulch film

[0066] The recycled and cleaned waste mulch film was ground and sieved to a particle size of less than 2 mm, and dried at 60°C for 12 hours to remove excess moisture.

[0067] (3) In-situ catalytic film cracking

[0068] See also Figure 2 10.0 kg of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst provided in this embodiment and 40.0 kg of pretreated ground film were co-fed and catalytically cracked in a nitrogen atmosphere at 760° C. in a reactor for 20 minutes to obtain synthesis gas and natural gas with yields of 40.3 wt% and 49.1 wt% respectively, and the coke yield was 3.1 wt%. Embodiment 2

[0069] 1. Raw materials and dosage: same as in Example 1

[0070] 2. Process steps and parameters for preparing hydrogen-type lignin recombinant multi-stage molecular sieve catalyst

[0071] (1) Synthesis of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and pretreatment of waste mulch film: The same treatment steps as in Example 1 were performed. The total surface area of ​​the catalyst calculated by the BET method was 382.3 m 2 / g.

[0072] (2) In-situ catalytic film cracking

[0073] 10.0 kg of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and 40.0 kg of pretreated ground film were co-fed and catalytically cracked in a nitrogen atmosphere at 800°C reactor for 20 minutes to obtain synthesis gas and natural gas with yields of 43.6 wt% and 44.3 wt% respectively, and the coke yield was 2.5 wt%. Embodiment 3

[0074] 1. Raw materials and dosage: same as in Example 1

[0075] 2. Process steps and parameters for preparing hydrogen-type lignin recombinant multi-stage molecular sieve catalyst

[0076] (1) Synthesis of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and pretreatment of waste mulch film: The same treatment steps as in Example 1 were performed. The total surface area of ​​the catalyst calculated by the BET method was 378.9 m 2 / g.

[0077] (2) In-situ catalytic film cracking

[0078] 10.0 kg of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and 40.0 kg of pretreated ground film were co-fed and catalytically cracked in a nitrogen atmosphere at 720°C reactor for 20 minutes to obtain synthesis gas and natural gas with yields of 38.2 wt% and 37.4 wt% respectively, and the coke yield was 3.7 wt%. Embodiment 4

[0079] 1. Raw materials and dosage

[0080] Y molecular sieve: 10.0kg

[0081] Lignin (extracted from eucalyptus and masson pine): 5.0kg

[0082] Sodium hydroxide (10%): 1.5 kg

[0083] Ammonium salt (8%): ​​15.0kg

[0084] Calcium hydroxide: 2.5kg

[0085] Ethyl acetate: 7.2 kg

[0086] Water: 28.8kg

[0087] Ground film: 30.0kg

[0088] 2. Process steps and parameters for preparing hydrogen-type lignin recombinant multi-stage molecular sieve catalyst

[0089] (1) Synthesis of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and pretreatment of waste mulch film: 10.0 kg of Y-type zeolite powder was uniformly mixed with 1.3 kg of 10% sodium hydroxide solution by mass, and stirred at 80 °C for 1 h in a condensation reflux device to obtain the aluminosilicate fragments required for the subsequent process. 5.0 kg of green bamboo lignin was emulsified with 36.0 kg of ethyl acetate and water with a volume ratio of 2:8, and added to the aluminosilicate fragments after alkali treatment. The zeolite-derived components in the green bamboo lignin solution were fully dispersed by stirring at 300 rpm, and the pH was adjusted to 50.5 with 0.2 kg of sodium hydroxide solution. The catalyst was hydrothermally recrystallized at 160°C in a high-pressure reactor, and the cooled slurry was centrifuged at 6500 rpm for 15 min and dried at 105°C for 6 h. The slurry was then exchanged with sodium ions in 15.0 kg of 8% ammonium nitrate solution. After filtering to remove excess water, the hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst precursor was evenly mixed with 2.5 kg of calcium hydroxide and activated by calcination at 600°C for 3 h to obtain a hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst. The sodium ion exchange was reacted at 90°C for 4 h, repeated twice, and then dried to constant weight. The total surface area of ​​the catalyst calculated by the BET method is 385.6 m 2 / g.

[0090] (2) In-situ catalytic film cracking

[0091] 15.0 kg of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and 30.0 kg of pretreated ground film were co-fed and catalytically cracked in a nitrogen atmosphere at 760°C reactor for 20 minutes to obtain synthesis gas and natural gas with yields of 45.2 wt% and 51.8 wt% respectively, and the coke yield was 1.9 wt%. Embodiment 5

[0092] 1. Raw materials and dosage: same as Example 4

[0093] 2. Process steps and parameters for preparing hydrogen-type lignin recombinant multi-stage molecular sieve catalyst

[0094] (1) Synthesis of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and pretreatment of waste mulch film: The same treatment steps as in Example 4 were performed. The total surface area of ​​the catalyst calculated by the BET method was 386.7 m 2 / g.

[0095] (2) In-situ catalytic film cracking

[0096] 15.0 kg of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and 30.0 kg of pretreated ground film were co-fed and catalytically cracked in a nitrogen atmosphere at 800°C reactor for 20 minutes to obtain synthesis gas and natural gas with yields of 49.0 wt% and 45.9 wt% respectively, and the coke yield was 1.5 wt%. Embodiment 6

[0097] 1. Raw materials and dosage: same as Example 4

[0098] 2. Process steps and parameters for preparing hydrogen-type lignin recombinant multi-stage molecular sieve catalyst

[0099] (1) Synthesis of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and pretreatment of waste mulch film: The same treatment steps were carried out as in Example 4. The total surface area of ​​the catalyst calculated by the BET method was 387.1 m 2 / g.

[0100] (2) In-situ catalytic film cracking

[0101] 15.0 kg of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and 30.0 kg of pretreated ground film were co-fed and catalytically cracked in a nitrogen atmosphere at 720°C reactor for 20 minutes to obtain synthesis gas and natural gas with yields of 41.7 wt% and 42.8 wt% respectively, and the coke yield was 2.1 wt%. Comparative Example 1

[0102] 1. Raw materials and dosage:

[0103] Y molecular sieve: 20.0kg

[0104] Ground film: 80.0kg

[0105] 2. Process steps and parameters

[0106] (1) Pretreatment of waste mulch film

[0107] The recycled and cleaned waste mulch film was ground and sieved to a particle size of less than 2 mm, and dried at 60°C for 12 hours to remove excess moisture.

[0108] (2) In-situ catalytic film cracking

[0109] 20.0 kg of Y molecular sieve catalyst without lignin reorganization treatment and 80.0 kg of pretreated waste mulch film were co-fed and catalytically cracked in a nitrogen atmosphere at 760 ° C reactor for 20 minutes to obtain synthesis gas and natural gas with yields of 35.1 wt% and 32.8 wt% respectively. The coke yield was 5.7 wt%. The total surface area of ​​the catalyst calculated by the BET method was 340.2 m 2 / g. Comparative Example 2

[0110] 1. Raw materials and dosage:

[0111] Y molecular sieve (the SEM image of the Y molecular sieve catalyst is shown in Figure 3 ):33.3kg

[0112] Ground film: 66.7kg

[0113] 2. Process steps and parameters

[0114] (1) Pretreatment of waste mulch film: the same treatment steps as in comparative example 1 were performed.

[0115] (2) In-situ catalytic film cracking

[0116] See also Figure 4 33.3 kg of Y molecular sieve catalyst without lignin reorganization treatment and 66.7 kg of pretreated waste mulch film were co-fed and catalytically cracked in a nitrogen atmosphere at 760 ° C for 20 minutes to obtain synthesis gas and natural gas with yields of 38.8 wt% and 35.2 wt% respectively, and the coke yield was 16.4 wt%. The total surface area of ​​the catalyst calculated by the BET method is 338.7 m 2 / g. Comparative Example 3

[0117] 1. Raw materials and dosage

[0118] Hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst: 20.0kg

[0119] Ground film: 80.0kg

[0120] 2. Process steps and parameters

[0121] (1) Recycling hydrogen-type lignin and reorganizing multi-stage Y molecular sieve catalyst

[0122] The hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst used in Example 1 was washed with ethanol and dried and recovered five times before being reused. The total surface area of ​​the catalyst calculated by the BET method was 380.6 m 2 / g.

[0123] (2) Pretreatment of waste mulch film

[0124] The recycled and cleaned waste mulch film was ground and sieved to a particle size of less than 2 mm, and dried at 60°C for 12 hours to remove excess moisture.

[0125] (3) In-situ catalytic film cracking

[0126] 20.0 kg of recycled hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and 80.0 kg of pretreated ground film were co-fed and catalytically cracked in a nitrogen atmosphere at 760°C reactor for 20 minutes to obtain synthesis gas and natural gas with yields of 40.6wt% and 48.7wt% respectively, and the coke yield was 3.2wt%.

[0127] The process parameters and yields of various products involved in the film catalytic cracking method used in the above-mentioned Examples 1 to 6 and Comparative Examples 1 to 3 are detailed in Table 1.

[0128] Table 1 Process parameters and yields of synthesis gas and natural gas in Examples 1 to 6 and Comparative Examples 1 to 3 of the present invention

[0129] project Catalyst type Catalyst to film mass ratio g / g Catalytic cracking temperature (reactor reaction temperature) / ℃ Synthesis gas yield / wt% Natural gas yield / wt% Coke yield / wt% Embodiment 1 Hydrogenated lignin reorganization multi-stage Y molecular sieve catalyst 1:4 760 40.3 49.1 3.1 Embodiment 2 Hydrogenated lignin reorganization multi-stage Y molecular sieve catalyst 1:4 800 43.6 44.3 2.5 Embodiment 3 Hydrogenated lignin reorganization multi-stage Y molecular sieve catalyst 1:4 720 38.2 37.4 3.7 Embodiment 4 Hydrogenated lignin reorganization multi-stage Y molecular sieve catalyst 1:2 760 45.2 51.8 1.9 Embodiment 5 Hydrogenated lignin reorganization multi-stage Y molecular sieve catalyst 1:2 800 49.0 45.9 1.5 Embodiment 6 Hydrogenated lignin reorganization multi-stage Y molecular sieve catalyst 1:2 720 41.7 42.8 2.1 Comparative Example 1 Y molecular sieve catalyst 1:4 760 35.1 32.8 5.7 Comparative Example 2 Y molecular sieve catalyst 1:2 760 38.8 35.2 16.4 Comparative Example 3 Recycled hydrogen lignin reconstituted into multi-stage Y molecular sieve catalyst 1:4 760 40.6 48.7 3.2

[0130] From the content shown in Table 1, it can be seen that in comparison with Example 1 and Comparative Example 1, it is found that under the action of the hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst, after 760°C catalytic cracking treatment, the conversion rate of the catalytic cracking of the ground film is significantly improved compared with the Y molecular sieve catalyst without lignin recombinant, and its syngas yield is increased by 14.8wt%, and the natural gas yield is increased by 49.7wt%. Comparing Example 1 and Comparative Example 3, it is found that after the used hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst is recycled and used repeatedly for 5 times, the yield of syngas and natural gas is not much different, indicating that the hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst maintains the original good catalytic performance after recovery. In contrast to Example 4 and Comparative Example 2, it is found that the dosage of the hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst is doubled, and after 760°C catalytic cracking treatment, the conversion rate of the catalytic cracking of the ground film is significantly improved compared with the use of the Y molecular sieve catalyst without lignin recombinant, and its syngas yield is increased by 16.5wt%, and the natural gas yield is increased by 47.2wt%. Comparing Example 1 and Example 4, it is found that after doubling the dosage of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst and carrying out 760°C catalytic cracking treatment, the catalytic cracking conversion rate of the ground film is improved, and its synthesis gas yield is increased by 12.2wt%, and the natural gas yield is increased by 5.5wt%. It can be seen that when the mass ratio of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst to ground film is only 1:4, the total yield of synthesis gas and natural gas is as high as 89.4wt% after catalytic cracking treatment at 760°C. On the one hand, the catalytic cracking temperature is reduced, that is, only 760°C treatment can achieve the ideal total yield of synthesis gas and natural gas, which greatly saves the energy consumption required for the catalytic cracking process; on the other hand, the amount of Y molecular sieve catalyst used in the catalytic cracking process is reduced, which greatly reduces the consumption of resources, and the yield of ground film catalytic cracking converted into synthesis gas and natural gas is greatly improved. In summary, after introducing the hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst, the present invention significantly improves the yield of catalytic cracking of ground film into synthesis gas and natural gas while reducing the amount of catalyst used. Preferably, when the mass ratio of hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst to ground film is 1:4 and the catalytic cracking temperature is 760°C, the synthesis gas yield can reach 40.3wt%, the natural gas yield can reach 49.1wt%, and the total yield can reach 89.4wt%. While saving resources and energy consumption, the cracking conversion efficiency of the ground film is improved, and the resource utilization of the recycled waste ground film is realized.

[0131] The mulch is treated with catalytic cracking by using the lignin recombinant multi-stage molecular sieve catalyst provided by the present invention, which can solve the technical problems of the difficulty in recycling the waste mulch after recycling and the low oil and gas production in the traditional cracking process, and the low selectivity of the oil and gas production types, and the low cracking efficiency, so as to achieve its high-value utilization. Since the hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst is used, the hierarchical pore structure can make the mulch more effectively converted into primary cracking intermediates, and the larger pore opening can accommodate the intermediate macromolecules derived from the cracking of the mulch, ensuring the accessibility of the catalyst active site and the activity of the catalyst. The presence of secondary mesopores is conducive to the rapid passage of various active substances decomposed in the mulch through the catalyst layer, solving the problem of serious coke deposition and short life of the traditional Y molecular sieve catalyst, and improving the yield of synthesis gas and natural gas products. At the same time, the hydrogen-type lignin recombinant multi-stage Y molecular sieve catalyst has good selectivity for the mulch cracking products, which is conducive to the catalytic cracking of the mulch to form synthesis gas and natural gas. Synthesis gas and natural gas are both important raw materials in the chemical fuel processing process, with good economic and environmental benefits, and improve the energy recovery rate of waste mulch. The present invention's exploration of the application of lignin also provides a new approach to high-quality utilization of biomass.

[0132] It should be noted that, although the above embodiments have been described in this article, the patent protection scope of the present invention is not limited thereby. Therefore, based on the innovative concept of the present invention, changes and modifications made to the embodiments described herein, or equivalent structures or equivalent process changes made using the contents of the present invention specification and drawings, directly or indirectly applying the above technical solutions to other related technical fields, are all included in the patent protection scope of the present invention.

Claims

1. A method for preparing a hydrogen-type lignin recombinant multi-stage molecular sieve catalyst, characterized in that: The following steps are involved: Preparation of aluminosilicate fragments: uniformly mixing a Y-type molecular sieve and a sodium hydroxide solution, stirring at 70° C. to 80° C. for 1 h to 2 h in a condensation reflux device, wherein Si / Al in the Y-type molecular sieve is 5, to obtain an aluminosilicate fragment solution; Emulsified lignin: emulsify lignin with an emulsifier formed by ethyl acetate and deionized water in a volume ratio of 2:8 to obtain an emulsified lignin solution; Preparing a precursor: uniformly mixing the emulsified lignin solution and the aluminosilicate fragment solution, adjusting the pH value to 8.5-9.5, and placing the mixture in a high-pressure reactor at 160° C. to 200° C. for hydrothermal recrystallization, cooling, solid-liquid separation, and drying, placing the obtained solid in an ammonium salt solution for ion exchange, and removing water to obtain a hydrogen-type lignin recombinant multi-stage molecular sieve catalyst precursor; Activation: The hydrogen-type lignin recombinant multi-stage molecular sieve catalyst precursor and the alkali activator are uniformly mixed at a mass ratio of 5 to 6:1, and calcined for activation to obtain the hydrogen-type lignin recombinant multi-stage molecular sieve catalyst.

2. The preparation method according to claim 1, characterized in that: The activation step has a calcination temperature of 450° C. to 600° C. and a calcination time of 3 h to 6 h.

3. The preparation method according to claim 1, characterized in that: In the step of emulsifying lignin, the ethyl acetate and deionized water are used to form an emulsifier and lignin in a mass ratio of 18 to 19.8:1, and the mixture is stirred and mixed at a rotation speed of 300 rpm to 800 rpm.

4. The preparation method according to claim 1, characterized in that: The ammonium salt solution is selected from at least one of ammonium nitrate, carbonate, acetate and phosphate.

5. The preparation method according to claim 4, characterized in that: The ammonium salt solution is an ammonium nitrate solution with a mass fraction of 8%-10%.

6. The preparation method according to claim 1, characterized in that: The alkali activator is selected from at least one of potassium hydroxide, calcium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium bicarbonate and sodium bicarbonate.

7. The preparation method according to claim 1, characterized in that: In the step of preparing the precursor, the solid-liquid separation is performed by centrifugation at a rotation speed of 6000 rpm to 7000 rpm.

8. The preparation method according to claim 1, characterized in that: The mass ratio of the Y-type molecular sieve to lignin is 2 to 4:

1.

9. A hydrogen-type lignin recombinant multi-stage molecular sieve catalyst, characterized in that: The compound is prepared by the preparation method according to any one of claims 1 to 8.

10. The use of the hydrogen-type lignin recombinant multi-stage molecular sieve catalyst according to claim 9 in catalytic cracking of waste polyethylene membranes, characterized in that: The following steps are involved: Pretreatment of waste polyethylene film: washing, grinding, drying and sieving the waste polyethylene film to obtain film fragments to be treated with an average particle size of less than 2 mm; In-situ catalytic cracking: the membrane fragments to be treated and the hydrogen-type lignin recombinant multi-stage molecular sieve catalyst are placed in a cracking reactor at a mass ratio of (1-2):4, wherein the membrane fragments to be treated and the hydrogen-type lignin recombinant multi-stage molecular sieve catalyst are isolated by thin quartz wool, the cracking temperature is 720°C-800°C, and nitrogen is filled at a flow rate of 80mL / min-120mL / min before opening the cracking reactor to obtain anaerobic conditions. The cracking reaction time is 15min-20min, and the nitrogen flow rate during the cracking reaction is <25mL / min as a carrier gas.

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