A catalyst, its preparation method, application, and method for catalytic hydrogenolysis

Abstract

This invention provides a catalyst, its preparation method, its application, and a method for catalytic hydrogenolysis. The catalyst comprises a molecular sieve and MoS2, with MoS2 supported on the molecular sieve. The preparation method includes the following steps: sublimation adsorption of a Mo-containing organic precursor and the molecular sieve; calcination decomposition of the material obtained after sublimation adsorption under an inert or reducing atmosphere; sulfidation treatment of the calcined material, followed by calcination under a reducing atmosphere. The catalyst is used in the catalytic hydrogenolysis of plastics or small molecule alkanes. The catalytic hydrogenolysis method is carried out under this catalyst. When used in the catalytic hydrogenolysis reaction of plastics or small molecule alkanes, the catalyst of this invention features a relatively low reaction temperature, tolerance to contamination, and high yield of liquid-phase products.

Description

Technical Field

[0001] This invention relates to the field of catalysis technology, and in particular to a catalyst, its preparation method, application, and a method for catalytic hydrogenolysis. Background Technology

[0002] Plastic products are widely used in daily life due to their low cost and excellent physical and chemical properties. Studies show that global annual plastic production currently reaches a staggering 380 million tons and is still growing rapidly. However, plastic itself is difficult to degrade naturally due to its high stability, making the disposal of large quantities of waste plastic a significant concern. Currently, only 12% of waste plastic can be reused through mechanical recycling, resulting in a low recycling rate accompanied by plastic degradation. The remaining approximately 40% is directly landfilled, 27% is incinerated to recover heat energy, and the rest is simply discarded into the environment. Regardless of the disposal method, significant environmental problems arise; therefore, exploring methods to recycle and reuse plastics has important economic and environmental value.

[0003] Although chemical treatment methods for plastics currently account for only 1% of waste plastic processing and are limited to relatively high-value plastics like PET, they still hold great promise due to their versatility, robustness, and potential for large-scale production. Thermocatalytic degradation, as the most universal chemical treatment method, can be applied to the degradation of various types of plastics, breaking them down into small-molecule alkanes. This not only solves the waste plastic problem but also generates renewable energy that can serve as a petroleum substitute.

[0004] The biggest problem in the recycling of waste plastics is that they must undergo strict pretreatment of cleaning and sorting. However, the high marginal cost of cleaning plastics hinders the further industrial application of chemical degradation of plastics. Therefore, there is an urgent need to design a catalyst with high stability and pollution tolerance, which can be unaffected by different types of waste plastics while also being tolerant to residual pollutants on the plastics. In the pursuit of high product selectivity in a hydrogen atmosphere, the degradation of waste plastics often involves two systems. The first is the hydrogenolysis reaction driven by noble metal Pt and Ru-based catalysts (Liu, S., et al. "Plastic waste to fuels by hydrocracking at mild conditions." Science Advances 7.17 (2021): eabf8283. Kots, PA, et al. "Polypropylene Plastic Waste Conversion to Lubricants over Ru / TiO2 Catalysts." ACS Catalysis 11. (2021): 8104-8115.), which utilizes noble metals to simultaneously complete the skeletal fracture and hydrogenation. This type of system often suffers from high catalyst costs, the generation of low-value straight-chain alkane products, a high proportion of C1C2 products, and the insensitivity of precious metals such as Pt and Ru to common pollutants in waste plastics such as S and As. These practical problems are often overlooked in literature studies, which often only use clean plastic particles. The second type of system is an acidic support system loaded with transition metals. This type of system often utilizes the C / C bond breaking ability of the acidic support and the hydrogenation ability of the transition metal to achieve the hydrogenation degradation of plastics.However, systems loaded with non-precious metals often require reaction temperatures above 350°C (Munir, Dureem, et al. Composite zeolite beta catalysts for catalytic hydrocracking of plastic waste to liquid fuels. Materials for Renewable and Sustainable Energy 9.2 (2020). Ding, Weibing, L. Jing, and LL Anderson. Hydrocracking and Hydroisomerization of High-Density Polyethylene and Waste Plastic over Zeolite and Silica Alumina-Supported Ni and NiMo Sulfides. Energy & Fuels 11.6 (1997):1219-1224.), consuming a significant amount of energy. Systems loaded with precious metals face the same problem. Therefore, there is an urgent need to propose a pollution-resistant system for hydrogenolysis of waste plastics that does not contain precious metals and can be achieved at temperatures of 250°C or below. Summary of the Invention

[0005] In view of the above-mentioned drawbacks of existing catalytic hydrogenolysis of waste plastics, such as the poor pollution tolerance and high cost of precious metal systems and the high reaction temperature required for non-precious metal systems, the purpose of this invention is to provide a catalyst, its preparation method, application, and catalytic hydrogenolysis method. When used to catalyze hydrogenolysis reactions, this catalyst has the characteristics of relatively low reaction temperature, pollution tolerance, and high yield of liquid phase products.

[0006] To achieve the above and other related objectives, the first aspect of the present invention provides a catalyst comprising a molecular sieve and MoS2, wherein the MoS2 is supported on the molecular sieve.

[0007] Preferably, it further includes at least one of the following technical features:

[0008] a1) Mo is loaded both inside and on the surface of the molecular sieve;

[0009] a2) The mass percentage of Mo in the catalyst is 2% to 5%, such as 2% to 2.6% or 2.6% to 5%, which is the mass of Mo / total mass of MoS2 and molecular sieve * 100%.

[0010] A second aspect of the present invention provides a method for preparing the above-mentioned catalyst, comprising the following steps:

[0011] b1) The Mo-containing organic precursor and molecular sieve were sublimated and adsorbed under vacuum conditions;

[0012] The material obtained after sublimation adsorption should be kept away from air as much as possible;

[0013] Mo-containing organic precursors and molecular sieves can be mixed (e.g., in a glove box), and under vacuum conditions, they can be homogenized by shaking while sublimating and adsorbing.

[0014] b2) The material obtained after sublimation adsorption is roasted and decomposed (activated) in an inert or reducing atmosphere;

[0015] The material obtained after roasting should be kept away from air as much as possible;

[0016] b3) The material obtained after roasting is subjected to sulfidation treatment, and then calcined (activated) in a reducing atmosphere to obtain the catalyst.

[0017] The obtained catalyst should be kept away from air as much as possible.

[0018] Sulfidation can be performed in an inert gas atmosphere containing hydrogen sulfide or in an atmosphere containing sulfur and hydrogen. Calcination in a reducing atmosphere is for activation and / or removal of excess sulfur. Sulfur and hydrogen can serve as low-hazard alternatives to hydrogen sulfide, and there is no issue of sulfur adsorption by a catalyst when hydrogen sulfide is used directly.

[0019] Preferably, the preparation method further includes: calcining and activating the molecular sieve before sublimation adsorption; and then sublimating and adsorbing the calcined and activated molecular sieve with the Mo-containing organic precursor under vacuum conditions.

[0020] After calcination, it can be taken out at a high temperature (the preferred temperature range for taking it out after calcination is above 90°C) and can be stored in an anhydrous environment such as a glove box, glove container, or desiccant box.

[0021] More preferably, the calcination temperature is 350°C to 550°C. Even more preferably, the calcination temperature is 400°C to 500°C.

[0022] More preferably, the calcination time is 5h to 10h.

[0023] Preferably, the above preparation method further includes at least one of the following technical features:

[0024] In step b1), the Mo-containing organic precursor is a molybdenum carbonyl organometallic compound; preferably, the molybdenum carbonyl organometallic compound is at least one of molybdenum hexacarbonyl (CAS No. 13939-06-5), molybdenum diacetonitrile tetracarbonyl (CAS No. 14126-87-5), and molybdenum cycloheptatriene tricarbonyl (CAS No. 12125-77-8); more preferably, it is molybdenum hexacarbonyl; the above-mentioned Mo-containing organic precursor contains a carbonyl group, is easily sublimated, and the ligands are easily removed;

[0025] b12) In step b1), the molecular sieve is a β molecular sieve or an HZSM5 molecular sieve;

[0026] β molecular sieves can be of the H type or the NH4 type. Na type can be replaced by ammonium chloride to become NH4 type. The preferred solution concentration for ammonium chloride replacement is 5wt% to 15wt% solution, the preferred time is 1 to 10 h, the preferred temperature is 50℃ to 80℃, and the preferred number of times is 1 to 6.

[0027] b13) In step b1), the SiO2 / Al2O3 molar ratio of the molecular sieve is 10 to 100; preferably 20 to 40.

[0028] b14) In step b1), the sublimation adsorption apparatus is a rotary evaporator with a double-row tube and a shaking table; preferably, it is a rotary evaporator.

[0029] b15) In step b1), the sublimation adsorption temperature is 20℃~50℃, such as 20℃~35℃ or 35℃~50℃;

[0030] b16) In step b1), the sublimation adsorption pressure is 0.1 mbar to 10 mbar, such as 0.1 mbar to 3 mbar or 3 mbar to 10 mbar;

[0031] b17) In step b1), the sublimation adsorption time is 0.5h to 10h, such as 0.5h to 1h or 1h to 10h;

[0032] In step b2), the inert atmosphere is a nitrogen atmosphere, and the reducing atmosphere is a nitrogen-hydrogen mixture atmosphere.

[0033] In step b2), the calcination decomposition temperature is 350℃~500℃, such as 350℃~400℃ or 400℃~500℃.

[0034] b23) In step b2), the calcination and decomposition time is 0.1h to 3h, such as 0.1h to 1.5h or 1.5h to 3h;

[0035] b24) In step b2), the temperature is increased to 350℃ to 500℃ at a heating rate of 5℃ / min to 10℃ / min for calcination and decomposition, such as 350℃ to 400℃ or 400℃ to 500℃.

[0036] b31) In step b3), the apparatus for vulcanization treatment is a tubular furnace, a fixed-bed reactor, or a reaction vessel; preferably a reaction vessel.

[0037] b32) In step b3), the material obtained after roasting is subjected to sulfidation treatment in an inert gas atmosphere containing hydrogen sulfide or in an atmosphere including sulfur and hydrogen; more preferably, the amount of sulfur used is 5% to 15% of the total mass of molybdenum and molecular sieve, such as 5% to 10% or 10% to 15%; more preferably, when the sulfidation treatment is carried out in an atmosphere including sulfur and hydrogen, the pressure of hydrogen is 5 atm to 30 atm, such as 5 atm to 15 atm or 15 atm to 30 atm.

[0038] b33) In step b3), the temperature of the vulcanization treatment is 100℃~250℃, such as 100℃~150℃ or 150℃~250℃;

[0039] b34) In step b3), the vulcanization treatment time is 5h to 15h, such as 5h to 10h or 10h to 15h;

[0040] b35) In step b3), the temperature is increased to 100-250°C at a heating rate of 5°C / min to 10°C / min for vulcanization treatment, such as 100°C-150°C or 150°C-250°C.

[0041] b36) In step b3), the reducing atmosphere is an atmosphere containing hydrogen.

[0042] b37) In step b3), the calcination temperature is 400℃~500℃, such as 400℃~450℃ or 450℃~500℃;

[0043] In step b3), the calcination time is 1 hour to 10 hours.

[0044] In step b3), calcination is carried out at a heating rate of 5℃ / min to 10℃ / min to 400℃ to 500℃, such as 400℃ to 450℃ or 450℃ to 500℃.

[0045] A third aspect of the present invention provides the use of the above-described catalyst in the catalytic hydrogenolysis reaction of plastics or small molecule alkanes.

[0046] Preferably, the catalytic hydrogenolysis reaction of the plastic or the small molecule alkane includes the following steps:

[0047] The plastic is crushed and then subjected to catalytic hydrogenolysis under the conditions of the catalyst and hydrogen; or, the small molecule alkane is subjected to catalytic hydrogenolysis under the conditions of the catalyst and hydrogen.

[0048] More preferably, it also includes at least one of the following technical features:

[0049] d1) The main component of the plastic is selected from at least one of polyolefin, polyvinyl chloride, polystyrene, nylon, polycarbonate, polyurethane, polyethylene terephthalate, polylactic acid and ABS plastic;

[0050] d2) In step d1), the mass content of impurities in the plastic or the small molecule alkane is ≤25%, that is, the mass of impurities is ≤25% of the mass of the plastic or the small molecule alkane; the impurities may include at least one of various impurities such as additives, water, acids, salts and lipids, etc., at a mass of 1 to 25%.

[0051] d3) In step d1), the size of the plastic particles obtained after crushing is 10 mesh to 1000 mesh;

[0052] d4) The weight-average molecular weight of the small molecule alkane is 114 to 300,000;

[0053] d5) The amount of catalyst used is 5% to 20% of the mass of the plastic or the small molecule alkane, such as 5% to 10% or 10% to 20%;

[0054] d6) The temperature for the catalytic hydrogenolysis reaction is 160℃~300℃; preferably 200℃~250℃;

[0055] d7) The hydrogen pressure for the catalytic hydrogenolysis reaction is 5 atm to 50 atm, such as 5 atm to 20 atm, 20 atm to 25 atm, 25 atm to 30 atm or 30 atm to 50 atm; preferably 20 atm to 30 atm.

[0056] d8) The time for catalytic hydrogenolysis reaction is 1h to 16h, such as 1h to 2h, 2h to 6h, 6h to 8h, 8h to 12h or 12h to 16h.

[0057] A fourth aspect of the present invention provides a method for catalytic hydrogenolysis, wherein the catalytic hydrogenolysis of plastics or small molecule alkanes is carried out in the presence of the above-mentioned catalyst.

[0058] Preferably, the method includes the following steps:

[0059] The plastic is pulverized and then subjected to a catalytic hydrogenolysis reaction under the conditions of the catalyst and hydrogen; or, the small molecule alkane is subjected to a catalytic hydrogenolysis reaction under the conditions of the catalyst and hydrogen.

[0060] More preferably, it also includes at least one of the following technical features:

[0061] e1) The main component of the plastic is selected from at least one of polyolefin, polyvinyl chloride, polystyrene, nylon, polycarbonate, polyurethane, polyethylene terephthalate, polylactic acid and ABS plastic;

[0062] e2) The mass content of impurities in the plastic or the small molecule alkane is ≤25%; the impurities may include at least one of various impurities such as additives, water, acids, salts and lipids, ranging from 1% to 25%;

[0063] e3) The size of the plastic particles obtained after crushing is 10 mesh to 1000 mesh;

[0064] e4) The weight-average molecular weight of the small molecule alkane is 114 to 300,000;

[0065] e5) The amount of catalyst used is 5% to 20% of the mass of the plastic or the small molecule alkane, such as 5% to 10%, 10% to 15% or 15% to 20%;

[0066] e6) The temperature for the catalytic hydrogenolysis reaction is 160℃~300℃, such as 160℃~200℃, 200℃~250℃ or 250℃~300℃; preferably 200℃~250℃;

[0067] e7) The hydrogen pressure for the catalytic hydrogenolysis reaction is 5 atm to 50 atm, such as 5 atm to 20 atm, 20 atm to 25 atm, 25 atm to 30 atm or 30 atm to 50 atm; preferably 20 atm to 30 atm.

[0068] e8) The time for catalytic hydrogenolysis reaction is 1h to 16h, such as 1h to 2h, 2h to 6h, 6h to 8h, 8h to 12h or 12h to 16h.

[0069] As described above, the invention has at least one of the following beneficial effects:

[0070] 1) The catalyst of this invention contains Mo in both the channels and the outer surface of the molecular sieve, with an S / Mo ratio lower than 2 of MoS2, and the valence state of Mo is slightly higher than +4. A small amount of O and Mo are bonded to the molecular sieve support, effectively anchoring the Mo nanoparticles. In the degradation of plastics such as polyolefins or small molecule alkanes, this catalyst exhibits good low-temperature hydrocracking activity at 250℃ and below. It also shows excellent reactivity in the degradation of everyday waste plastics and contaminated waste plastics, with the products mainly being C5-C16 branched alkanes and fewer gaseous products, achieving good technical results.

[0071] 2) The catalyst of this invention has the properties of high dispersion, high stability and high pollution tolerance.

[0072] 3) The catalyst preparation method of the present invention uses carbonyl molybdenum organometallic compound as the Mo species. It is sublimated and diffused into the molecular sieve channel under vacuum conditions. First, Mo sites anchored on the molecular sieve are generated by a one-step high temperature process. Then, the molecular sieve catalyst with nano-molybdenum sulfide particles supported is prepared by hydrogen sulfide treatment for use in the catalytic hydrogenolysis reaction of plastics.

[0073] 4) In the catalyst preparation method of this invention, the Mo-containing organic precursor and molecular sieve are sublimated and adsorbed under vacuum conditions. This effectively adsorbs molybdenum both inside and on the surface of the molecular sieve, and effectively avoids molybdenum aggregation, achieving highly dispersed molybdenum loading. The activation process of the Mo-containing organic precursor (calcination and decomposition under an inert or reducing atmosphere) effectively enhances the interaction between Mo and the molecular sieve, allowing Mo to combine with oxygen on the molecular sieve and effectively anchoring Mo nanoparticles. This alleviates the accumulation of Mo species in the surface-loaded catalyst, effectively improving the stability of the catalyst during the reaction process.

[0074] 5) The catalyst of this invention exhibits good low-temperature hydrocracking activity at 250°C and below when applied to the catalytic degradation of plastics such as polyolefins or small molecule alkanes. It also shows excellent reactivity in the degradation of waste plastics used in daily life and contaminated waste plastics. The products are mainly C5-C16 branched alkanes with fewer gaseous products, achieving good technical results.

[0075] 6) The catalyst of this invention, namely the MoS2 molecular sieve catalyst, can effectively utilize the C-C bond breaking ability of molecular sieves and the hydrogenation ability of MoS2. Without the doping of precious metals, it can realize the catalytic hydrogenolysis reaction of plastics such as polyolefins or small molecule alkanes at relatively low temperatures of 250°C and below.

[0076] 7) The catalyst of this invention is suitable for the catalytic degradation of plastics such as polyolefins or small molecule alkanes. At reaction pressures of 5–50 atm, reaction temperatures of 160–300°C, reaction times of 1–16 h, and catalyst loadings of 5 wt%–20 wt%, it exhibits high activity in the hydrogenolysis of polyolefins, primarily producing liquid-phase products. Low-value products such as C1 and C2, which are more abundant in noble metal catalysts, are also present in relatively small quantities. A certain conversion rate has also been observed in other plastics besides polyolefins. Furthermore, when processing plastics, small amounts of other plastics do not affect the reaction performance; that is, the catalyst of this invention can be applied to various plastic systems, achieving the degradation process at relatively low temperatures. Attached Figure Description

[0077] Figure 1 TEM, elemental analysis chromatograms of Mo and S and HAADF-STEM (scale bar: 20 nm) of the catalyst used in all examples.

[0078] in: Figure 1 a represents the TEM image of the catalyst.

[0079] Figure 1 b is the elemental analysis diagram of Mo and S in the catalyst.

[0080] Figure 1 c represents the HAADF-STEM of the catalyst.

[0081] Figure 2 STEM images (scale bar: 20 nm) of the catalyst used in all examples before and after the reaction.

[0082] in: Figure 2 a is a STEM image of the catalyst before the reaction.

[0083] Figure 2 b is a STEM image of the catalyst after the reaction.

[0084] Figure 3 XRD pattern of the catalyst used in all embodiments.

[0085] Figure 4 XPS plot of the catalyst used in all embodiments.

[0086] Figure 5 The graph shows the reaction performance of the catalyst under different reaction conditions.

[0087] in: Figure 5 a represents the reaction performance of different catalysts (1g of low-density polyethylene (MB9500) powder, 10wt% catalyst loading, reaction conditions 200℃, 30atmH2, 16h; *1g of polyethylene wax (AC-6A) powder, 10wt% catalyst loading, reaction conditions 250℃, 20atmH2, 6h).

[0088] Figure 5 b is a graph showing the reaction performance of the catalyst at different reaction times (1g of low-density polyethylene (MB9500) powder, 10wt% catalyst loading, reaction conditions 250℃, 20atmH2).

[0089] Figure 5 c represents the reaction performance of the catalyst at different reaction temperatures (1g of low-density polyethylene (MB9500) powder, 10wt% catalyst loading, reaction conditions 20 atm H2, 6h; *15wt% catalyst loading, reaction conditions 25 atm H2, 16h).

[0090] Figure 5 d is the reaction performance diagram of the catalyst under different reaction pressures (1g of low-density polyethylene (MB9500) powder, 10wt% catalyst loading, reaction conditions 250℃, 2h).

[0091] Figure 6 The reaction performance of different polyolefin plastics at 200℃ is shown in the figure (catalyst loading 10wt%, reaction conditions 200℃, 30atmH2, 16h).

[0092] Figure 7 This is a graph showing the reaction performance of the catalyst under different additives or impurities.

[0093] The mixture consists of: 1 mixed salts, which includes 0.05 g of 5 wt% CaCO3, 5 wt% FeCl3, 5 wt% MgSO4, and 5 wt% KBr; 2 mixed salts, which includes 5 wt% Na2CO3, 5 wt% PbSO4, 5 wt% ZnCl2, and 5 wt% CuBr2; (1 g LDPE, 250 °C, 25 atm H2, 6 h, catalyst loading is 10%).

[0094] Figure 8 The graph shows the hydrocracking reaction performance of different plastic products.

[0095] in: Figure 8 Figure a shows the hydrocracking performance of different plastic products. The reaction conditions are: 1g plastic product, 250℃, 25 atm H2, 12h, catalyst loading of 10%, *8h, **catalyst loading of 15%.

[0096] Figure 8 b is Figure 8 A diagram showing the corresponding plastic used. Detailed Implementation

[0097] The present invention is further illustrated below with reference to the embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods and reagents not specified in the following embodiments, unless otherwise stated, were performed or prepared under conventional conditions or conditions recommended by the manufacturer.

[0098] Example 1

[0099] The catalyst was prepared using molybdenum hexacarbonyl as the raw material and Hβ molecular sieve. The mass of molybdenum in the molybdenum hexacarbonyl was 3% of the mass of the Hβ molecular sieve (SiO2 / Al2O3 molar ratio of 25:1). It was loaded at 35℃ and 3mbar vacuum for 1h (sublimation adsorption), activated at 400℃ for 1.5h (calcination decomposition) with 8% nitrogen-hydrogen mixture (hydrogen volume percentage of 8%), and then sulfided at 150℃ in a sulfur and 15atm H2 atmosphere for 10h (sulfidation treatment). The amount of sulfur used was 10% of the total mass of molybdenum and molecular sieve. The product was then activated at 450℃ for 3h (calcination) with 8% nitrogen-hydrogen mixture (hydrogen volume percentage of 8%).

[0100] The TEM, elemental analysis maps of Mo and S, and HAADF-STEM images of the catalysts obtained by the above preparation method are shown below. Figure 1 1a~1c.

[0101] STEM images of the catalyst before and after the reaction are shown below. Figure 2 In sections 2a and 2b, the reaction refers to the catalytic cracking reaction of low-density polyethylene (MB9500, Mw=300k) under the conditions of 250℃, 6h, and 20atmH2, with the mass ratio of catalyst to low-density polyethylene powder being 1:10.

[0102] The catalyst XRD pattern is shown below. Figure 3 .

[0103] The final Mo content of the catalyst, as determined by XPS analysis, was 2.6%. (XPS graph shown below) Figure 4 This catalyst was used in all subsequent embodiments.

[0104] Low-density polyethylene (MB9500, Mw=300k) powder or polyethylene wax powder (AC-6A, Mw=4k) obtained directly from purchase is mixed with the prepared catalyst powder in a 10:1 ratio. The mixture is then reacted in a high-pressure reactor under specific temperature and pressure conditions for a certain time to successfully obtain the degradation product. Figure 5 (5a-5d). As can be seen from the figure, the catalyst synthesized by this method (i.e., ...) Figure 5 MoS2-Hbeta in a) compared to the molecular sieve itself (i.e. Figure 5 a) and a simple mixture of molecular sieves and MoS2 (i.e., Hbeta) and MoS2. Figure 5The conversion rate of Hbeta + 10% MoS2 in (a) is much higher. High conversion rates can be achieved for both the high molecular weight MB9500 (Mw = 300k) and the low molecular weight AC-6A (Mw = 4k) under the corresponding reaction conditions. Reaction time and temperature have a significant impact on the conversion of the product; the conversion rate of polyethylene increases significantly with increasing time and temperature. Pressure has some influence on the reaction; with increasing pressure, the conversion rate initially increases and then remains approximately constant.

[0105] Example 2

[0106] Different polyolefin powders (LDPE MB9500, PP H1500, LLDPE LL6210RQ, HDPE HMA-016) obtained directly from the market and the prepared catalyst powder were mixed at a mass ratio of 10:1, at 200℃, for 16 h, and at 30 atm H2 (…). Figure 6 The reaction performance of different polyolefin powders was observed under the conditions of 200℃. Various polyolefins exhibited excellent catalytic hydrocracking performance.

[0107] Example 3

[0108] Low-density polyethylene powder (LDPE MB9500) obtained directly and the catalyst were mixed in different proportions (Table 1) under reaction conditions of 25 / 20 atm H2, 6 h, and 250 °C. It can be seen that good conversion rates were observed from 5% to 20%, and the reaction activity continuously increased with increasing loading. From the perspective of both the normal and isomeric C4 products, the products are mainly isomerized hydrocarbons.

[0109] Table 1

[0110]

[0111] Example 4

[0112] Low-density polyethylene (MB9500, Mw=300k) powder obtained directly from the market was mixed with catalyst at a mass ratio of 1:10. Then, various contaminants that might be encountered in real waste plastic systems, including moisture, acidic environments, plastic additives, and different inorganic salts, were added and mixed in a specific ratio. Figure 7 The reaction was carried out in a high-pressure reactor at 250℃ for 6 hours under a hydrogen atmosphere at 25 atm. As shown in the figure below, the catalyst exhibits good tolerance to various contaminants, and the product still demonstrates high selectivity for liquid-phase hydrocarbons.

[0113] Example 5

[0114] Polypropylene (PP), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polystyrene powder (PP H1500, LDPE MB9500, HDPE HMA-016, PS MN-1-310), and the prepared catalyst powder were mixed in a certain proportion (Table 2). The mixture was then reacted in a high-pressure reactor at 250℃ for 8 hours under a hydrogen atmosphere of 25 atm, maintaining a relatively high conversion rate (Table 2, No. 9). As can be seen from (Nos. 1-8), the catalyst exhibits a certain conversion rate for various plastics other than polyethylene and polypropylene, including polyvinyl chloride (PVC), PVC (PBM-6), polystyrene (PS) (MN-1-310), polyethylene terephthalate (PET) (FB530), polyurethane (TPU) (HT-8757), nylon 6PA6 (1013B), ABS (GP-22), polycarbonate (PC) (2407), and polylactic acid (PLA) (PBM-6). Adding different types of other plastics (Table 2, item 10) to the mixed polyolefins also maintained a relatively good reaction conversion rate. Furthermore, commercially available plastic products ( Figure 8 The reaction was carried out after cutting up 8a and 8b (I PE disposable plastic droppers, II HDPE reaction reagent bottles, III PP meltblown fabric masks, IV PE disposable plastic wrap) into small pieces, and the conversion rate was also good. It is worth noting that used, contaminated, and completely unwashed plastic ( Figure 8 The PP plastic cup (V, which has contained porridge) and the PP lunch box (VI, which has contained rice) also showed good reactivity in the reaction.

[0115] Table 2

[0116]

[0117] The above embodiments are for illustrating the implementation schemes disclosed in this invention and should not be construed as limiting the invention. Furthermore, various modifications listed herein, as well as variations in the methods and compositions of the invention, will be apparent to those skilled in the art without departing from the scope and spirit of the invention. Although the invention has been specifically described in conjunction with various specific preferred embodiments, it should be understood that the invention should not be limited to these specific embodiments. In fact, various modifications as described above that are obvious to those skilled in the art to obtain the invention should be included within the scope of this invention.

Claims

1. The use of a catalyst in the catalytic hydrogenolysis reaction of plastics, characterized in that, The catalyst comprises a molecular sieve and MoS2, wherein MoS2 is supported on the molecular sieve; The catalytic hydrogenolysis reaction of the plastic includes the following steps: The plastic is pulverized and then subjected to a catalytic hydrogenolysis reaction under the conditions of the catalyst and hydrogen.

2. The use as described in claim 1, characterized in that, It also includes at least one of the following technical features: a1) Mo is loaded both inside and on the surface of the molecular sieve; a2) The mass percentage of Mo in the catalyst is 2%~5%.

3. The use as described in claim 1, characterized in that, The preparation method of the catalyst includes the following steps: b1) Sublimation adsorption of Mo-containing organic precursor and molecular sieve under vacuum conditions; b2) The material obtained after sublimation adsorption is roasted and decomposed in an inert or reducing atmosphere; b3) The material obtained after roasting is subjected to sulfidation treatment, and then calcined in a reducing atmosphere to obtain the catalyst.

4. The use as described in claim 3, characterized in that, The preparation method further includes: calcining and activating the molecular sieve before sublimation adsorption; then sublimating and adsorbing the calcined and activated molecular sieve with the Mo-containing organic precursor under vacuum conditions; the calcination and activation temperature is 350℃~550℃; and the calcination and activation time is 5h~10h.

5. The use as described in claim 3 or 4, characterized in that, The preparation method further includes at least one of the following technical features: b11) In step b1), the Mo-containing organic precursor is a carbonyl molybdenum metal organometallic compound; b12) In step b1), the molecular sieve is a β molecular sieve or an HZSM5 molecular sieve; b13) In step b1), the SiO2 / Al2O3 molar ratio of the molecular sieve is 10~100; b14) In step b1), the sublimation adsorption apparatus is a rotary evaporator or a double-row tube with a shaking table; b15) In step b1), the temperature for sublimation adsorption is 20℃~50℃; b16) In step b1), the sublimation adsorption pressure is 0.1 mbar to 10 mbar; b17) In step b1), the sublimation adsorption time is 0.5h~10h; b21) In step b2), the inert atmosphere is a nitrogen atmosphere, and the reducing atmosphere is a nitrogen-hydrogen mixture atmosphere; b22) In step b2), the calcination decomposition temperature is 350℃~500℃; In step b2), the calcination and decomposition time is 0.1 h to 3 h. b24) In step b2), the temperature is increased to 350℃~500℃ at a heating rate of 5~10℃ / min for calcination and decomposition; b31) In step b3), the vulcanization treatment apparatus is a tubular furnace, a fixed-bed reactor, or a reaction vessel; b32) In step b3), the material obtained after roasting is subjected to sulfidation treatment in an inert gas atmosphere containing hydrogen sulfide or in an atmosphere including sulfur and hydrogen. In step b3), the vulcanization temperature is 100℃~250℃; b34) In step b3), the vulcanization treatment time is 5h to 15h; b35) In step b3), the temperature is increased to 100℃~250℃ at a heating rate of 5℃ / min~10℃ / min for vulcanization treatment; b36) In step b3), the reducing atmosphere is an atmosphere containing hydrogen. b37) In step b3), the calcination temperature is 400℃~500℃; b38) In step b3), the calcination time is 1 h ~ 10 h; In step b3), the temperature is increased to 400℃~500℃ at a heating rate of 5℃ / min~10℃ / min for calcination.

6. The use as described in claim 5, characterized in that, It also includes at least one of the following technical features: b111) The carbonyl molybdenum organometallic compound is selected from at least one of hexacarbonyl molybdenum, diacetonitrile tetracarbonyl molybdenum, and cycloheptatriene tricarbonyl molybdenum; (b131) The SiO2 / Al2O3 molar ratio of the molecular sieve is 20~40; b141) The device for sublimation adsorption is a rotary evaporator; (b321) The amount of sulfur used is 5% to 15% of the total mass of molybdenum and molecular sieve; (b322) When performing sulfidation treatment in an atmosphere containing sulfur and hydrogen, the pressure of hydrogen is 5 atm to 30 atm.

7. The use as described in claim 1, characterized in that, It also includes at least one of the following technical features: d1) The plastic is selected from at least one of polyolefins, polyvinyl chloride, polystyrene, nylon, polycarbonate, polyurethane, polyethylene terephthalate, polylactic acid and ABS plastic; d2) The mass content of impurities in the plastic is ≤25%; d3) The size of the plastic particles obtained after crushing is 10 mesh to 1000 mesh; d5) The amount of catalyst used is 5% to 20% of the mass of the plastic; d6) The temperature for the catalytic hydrogenolysis reaction is 160℃~300℃; d7) The hydrogen pressure for the catalytic hydrogenolysis reaction is 5 atm to 50 atm; d8) The catalytic hydrogenolysis reaction time is 1h~16h.

8. A method for catalytic hydrogenolysis, characterized in that, The catalytic hydrogenolysis of plastics is carried out in the presence of a catalyst; the catalyst comprises a molecular sieve and MoS2, with MoS2 supported on the molecular sieve; The plastic is pulverized and then subjected to a catalytic hydrogenolysis reaction under the conditions of the catalyst and hydrogen.

9. The method for catalytic hydrogenolysis as described in claim 8, characterized in that, It also includes at least one of the following technical features: a1) Mo is loaded both inside and on the surface of the molecular sieve; a2) The mass percentage of Mo in the catalyst is 2%~5%.

10. The method for catalytic hydrogenolysis as described in claim 8, characterized in that, It also includes at least one of the following technical features: e1) The plastic is selected from at least one of polyolefins, polyvinyl chloride, polystyrene, nylon, polycarbonate, polyurethane, polyethylene terephthalate, polylactic acid and ABS plastic; e2) The mass content of impurities in the plastic is ≤25%; e3) The size of the plastic particles obtained after crushing is 10 mesh to 1000 mesh; e5) The amount of catalyst used is 5% to 20% of the mass of the plastic; e6) The temperature for the catalytic hydrogenolysis reaction is 160℃~300℃; e7) The hydrogen pressure for the catalytic hydrogenolysis reaction is 5 atm to 50 atm; e8) The catalytic hydrogenolysis reaction time is 1h~16h.

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