A rapid pyrolysis catalytic apparatus and method using latent heat of Zn vapor heating

Abstract

The application discloses a rapid pyrolysis catalytic device and method using Zn vapor latent heat heating, and the method comprises the following steps: putting a pyrolysis substance into a zinc oxide reaction dish, introducing inert gas into a superheated vapor inlet, and evacuating air in the pyrolysis catalytic device; starting a pyrolysis reaction furnace, preparing zinc vapor, and adjusting a pressure regulating valve so that the pressure in the pyrolysis reaction furnace reaches a required pressure; and collecting and processing pyrolysis products at a pyrolysis product outlet. The method provided by the application controls the boiling point of Zn vapor in a small range by pressure, utilizes the high vaporization latent heat of high-temperature Zn vapor and the high contact rate with the pyrolysis substance to provide sufficient heat for the pyrolysis substance in an instant, realizes short-time and high-efficiency pyrolysis, and reduces the generation of process by-products.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of hydrogen energy production and utilization, waste treatment and resource recycling, environmental protection, and particularly relates to a rapid pyrolysis catalytic device and method using Zn vapor latent heat heating. BACKGROUND

[0002] With the progress of social science and technology, energy demand is increasing, and traditional fossil fuels, as an important non-renewable energy, are gradually depleted, therefore, it is urgent to develop renewable clean energy to replace traditional fossil fuels. Plastic has the advantages of easy processing, low cost, durability, etc., and its consumption is increasing. Therefore, how to convert and resource utilization of waste plastics has become an important research direction.

[0003] Catalytic pyrolysis is an important form of pyrolysis, which can reduce the activation energy of the reaction through catalysts, improve the reaction rate, and directionally generate more valuable products such as aromatic hydrocarbons, other hydrocarbon products and pyrolysis oil. Monocyclic aromatic hydrocarbons are an important class of chemicals, for example, benzene series, the main representative compounds are benzene, toluene, ethylbenzene and xylene, etc. Benzene has multiple uses as a precursor for plastic synthesis; toluene can be used as a fuel additive to improve the octane rating of gasoline; ethylbenzene is widely used in the synthesis of styrene and the manufacture of polystyrene; xylene can be used as a solvent, gasoline blending agent, plasticizer and raw material for plastic production. Pyrolysis oil can be used as a fuel to replace oil or natural gas, and is widely used in industrial boilers, power plants and other places, and even can be refined further for transportation fuels (such as diesel and gasoline). In the case of tight oil resources, pyrolysis oil is considered as a potential alternative to crude oil.

[0004] Waste plastics are complex in type, stable in structure and high in polymerization degree. The traditional high-temperature thermal chemical waste plastic pyrolysis process has high reaction temperature and complex product composition, which requires very harsh catalyst system and reaction equipment. Specifically, the existing heating technology has the following problems that are not suitable for industrial pyrolysis: (1) In terms of heating and temperature rising: the problem of traditional heating method is that it is difficult to accurately control the process temperature, the equipment cost is high, the demand for electric energy consumption is extremely large, the heating speed is slow, the energy efficiency is not high, and the operation process has safety risks. (2) In terms of the generated target product: the reaction of ordinary pyrolysis experiment often produces some by-products due to slow heating, which not only wastes raw materials but also may inhibit the rate of the main reaction, thereby affecting the yield of the target product.

[0005] Therefore, the prior art still needs to be improved and innovated. SUMMARY

[0006] In view of the above shortcomings of the prior art, the present application provides a rapid pyrolysis catalytic device and method using Zn vapor latent heat heating, to solve the problem that ordinary pyrolysis process produces some by-products due to slow heating.

[0007] The technical scheme adopted by the present application to solve the above technical problems is as follows:

[0008] In a first aspect, the present application provides a rapid pyrolysis catalytic device using Zn vapor latent heat heating, which comprises a pyrolysis reaction furnace, a catalytic stick, and a pyrolysis reaction dish, wherein the pyrolysis reaction furnace is internally provided with a pressure regulating valve, and the two ends of the pyrolysis reaction furnace are sealed by sealing flanges, and a superheated vapor inlet and a pyrolysis product outlet are respectively formed on the sealing flanges at the two ends of the pyrolysis reaction furnace; the catalytic stick is located inside the pyrolysis reaction furnace, one end of the catalytic stick is connected with the pyrolysis reaction dish, and the other end is connected with the sealing flange close to the superheated vapor inlet; the pyrolysis device further comprises a pyrolysis product collection device, which is connected with the pyrolysis reaction furnace through the pyrolysis product outlet and is used for collecting and processing pyrolysis products.

[0009] Preferably, the catalytic stick comprises a molecular sieve and a zinc catalyst loaded on the molecular sieve, and the pyrolysis reaction dish is a zinc oxide reaction dish.

[0010] Preferably, the pyrolysis product collection device comprises a condenser, a liquid product collection bottle, a gas washing bottle, and a gas collection bag connected in sequence, and the condenser is connected with the pyrolysis reaction furnace through the pyrolysis product outlet.

[0011] Preferably, the catalytic stick is provided with a temperature measuring thermocouple and a gas pressure sensor, and the zinc oxide reaction dish is provided with a temperature measuring thermocouple and a gas pressure sensor.

[0012] Preferably, the temperature measuring thermocouples are provided in multiple, and are uniformly arranged on the surface of the catalytic stick and the upper and lower surfaces of the zinc oxide reaction dish.

[0013] In a second aspect, the present application provides a pyrolysis catalytic method based on the above pyrolysis device, which comprises the following steps:

[0014] Placing a pyrolysis substance into a zinc oxide reaction dish, introducing an inert gas into the superheated vapor inlet, and evacuating the air in the pyrolysis device;

[0015] Turning on the pyrolysis reaction furnace to prepare zinc vapor, and adjusting the pressure regulating valve to make the pressure in the pyrolysis reaction furnace reach a required pressure;

[0016] Collecting and processing pyrolysis products at the pyrolysis product outlet.

[0017] Preferably, the molecular sieve is selected from one or more of ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-12 molecular sieve, and Beta molecular sieve.

[0018] Preferably, the pore size of the molecular sieve is 0.51-0.56 nm.

[0019] Preferably, the molecular sieve is further loaded with 0.1-3 g of zinc oxide.

[0020] Advantages:

[0021] The application discloses a rapid pyrolysis catalytic device and method using Zn vapor latent heat heating. Compared with a traditional pyrolysis furnace, the pyrolysis catalytic device provided by the application has the problems of low heating efficiency, uneven product distribution, and more pollution products, and the like. The method provided by the application releases latent heat in a phase change process of zinc vapor, provides an efficient and accurate heating mode, and is used for promoting a pyrolysis reaction of a pyrolysis material. The zinc vapor also catalyzes and regulates the reaction, and increases production of liquid products and high-value-added products. The application can be widely applied to pyrolysis treatment processes of organic matters such as coal, plastics and waste, and is especially suitable for occasions of improving pyrolysis efficiency and reducing energy consumption. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 The figure is a schematic diagram of the pyrolysis catalytic device of the preferred embodiment of the application.

[0023] Figure 2 The figure is an exploded view of the pyrolysis catalytic device of the preferred embodiment of the application and an illustration of each part.

[0024] Figure 3 The figure is a partial detail view of the pyrolysis catalytic device of the preferred embodiment of the application.

[0025] Figure 4 The figure is a schematic diagram of the structure of the condenser tube in the pyrolysis catalytic device of the preferred embodiment of the application.

[0026] Figure 5 The figure is a schematic diagram of the structure of the liquid product collection bottle in the pyrolysis catalytic device of the preferred embodiment of the application.

[0027] Figure 6 The figure is a schematic diagram of the structure of the gas washing bottle in the pyrolysis catalytic device of the preferred embodiment of the application.

[0028] Figure 7 The figure is a schematic diagram of the structure of the gas collection bag in the pyrolysis catalytic device of the preferred embodiment of the application.

[0029] Figure 8 The figure is an X-ray single crystal diffraction structure diagram of the ZSM-5 molecular sieve.

[0030] Wherein, 1, pyrolysis reaction furnace, 2, catalytic stick, 3, pyrolysis reaction dish, 4, sealing flange, 5, superheated steam inlet, 6, pyrolysis product outlet, 7, pyrolysis product collection device, 71, condenser tube, 72, liquid product collection bottle, 73, gas washing bottle, 74, gas collection bag. DETAILED DESCRIPTION

[0031] The application provides a rapid pyrolysis catalytic device and method using Zn vapor latent heat heating, in order to make the purpose, technical scheme and effect of the application more clear and definite, the application is further described in detail below. It should be understood that the specific embodiments described herein are only used to explain the application and not to limit the application.

[0032] The application provides a rapid pyrolysis catalytic device using Zn vapor latent heat heating, as shown in the figure, Figures 1-3 The pyrolysis catalytic device includes a pyrolysis reaction furnace 1, a catalytic stick 2 and a pyrolysis reaction dish 3. The pyrolysis reaction furnace is internally provided with a pressure regulating valve. The two ends of the pyrolysis reaction furnace are sealed by sealing flanges 4. A superheated steam inlet 5 and a pyrolysis product outlet 6 are respectively formed in the sealing flanges 4 at the two ends of the pyrolysis reaction furnace 1. The catalytic stick 2 is located inside the pyrolysis reaction furnace 1. One end of the catalytic stick 1 is connected with the pyrolysis reaction dish 3, and the other end is connected with the sealing flange 4 close to the superheated steam inlet 5. The pyrolysis device further includes a pyrolysis product collection device 7. The pyrolysis product collection device 7 is connected with the pyrolysis reaction furnace 1 through the pyrolysis product outlet 6, and is used for collecting and processing pyrolysis products.

[0033] The catalytic stick 2 includes a molecular sieve and a zinc catalyst loaded on the molecular sieve. The pyrolysis reaction dish 3 is a zinc oxide reaction dish.

[0034] In some embodiments, the sealing flange 4 can be a high-temperature-resistant and corrosion-resistant high-pressure sealing flange or other forms meeting the requirements according to the reaction requirements. The pyrolysis reaction furnace 1 is a high-temperature-resistant quartz glass pyrolysis reaction furnace.

[0035] In some embodiments, the pyrolysis product collection device 7 includes a condenser tube 71 (see Figure 4 ), a liquid product collection bottle 71 (see Figure 5 ), a gas washing bottle 73 (see Figure 6 ) and a gas collection bag 74 (see Figure 7 ) connected in sequence. The condenser tube 71 is connected with the pyrolysis reaction furnace 1 through the pyrolysis product outlet 6.

[0036] In some embodiments, the catalytic stick 2 is welded with the zinc oxide reaction vessel as a whole and is fixed in the center of the pyrolysis reactor 1. A spherical condenser 71 is connected after the pyrolysis product outlet 5 to cool the gaseous oil and gas mixture, and then the condensed liquid product is collected by the liquid product collection bottle 72. The soluble gaseous product is collected by the gas washing bottle 73 after the liquid product collection bottle 72. Finally, the remaining gaseous product is collected by the gas collection bag 74.

[0037] In some embodiments, the catalytic stick 2 is provided with a temperature measuring thermocouple and a gas pressure sensor, and the zinc oxide reaction vessel is provided with a temperature measuring thermocouple and a gas pressure sensor.

[0038] In some embodiments, a plurality of temperature measuring thermocouples are provided, which are uniformly arranged on the surface of the catalytic stick 2 and the upper and lower surfaces of the zinc oxide reaction vessel.

[0039] In some embodiments, a temperature measuring thermocouple is arranged every 30 cm on the surface of the catalytic stick 2.

[0040] The pyrolysis catalytic method based on the pyrolysis catalytic device described above is provided, and the method comprises the following steps:

[0041] The pyrolysis material is placed in the zinc oxide reaction vessel, inert gas is introduced into the superheated steam inlet, and the air in the pyrolysis device is exhausted;

[0042] The pyrolysis reactor is started, zinc vapor is prepared, and the pressure regulating valve is adjusted to make the pressure in the pyrolysis reactor reach the required pressure;

[0043] The pyrolysis product is collected and treated at the pyrolysis product outlet.

[0044] The embodiment of the present application takes ZSM-5 / Zn supported catalyst (i.e. Zn supported on ZSM-5 molecular sieve) as an example to illustrate the process and principle. The embodiment of the present application method first passes inert gas to exhaust the air in the whole catalytic pyrolysis device, and after ensuring the high pressure air tightness of the pyrolysis reaction furnace, the ZSM-5 / Zn supported catalyst carrier and the Zn element and ZnO on the ZnO reaction dish will evaporate to form vapor through the high temperature environment, and the pressure regulating valve on the pyrolysis reaction furnace is adjusted, which adjusts the pyrolysis reaction furnace to the specified boiling point pressure required by pressing the inert gas, and the boiling point of Zn vapor is accurately adjusted according to the Clapeyron equation, and the high temperature Zn vapor contacts with the reactant to utilize the latent heat of vaporization of phase change to release heat and heat pyrolysis. The embodiment of the present application utilizes the high latent heat of vaporization of high temperature Zn vapor and its high contact rate with pyrolysis substances to provide sufficient heat for pyrolysis substances in an instant, and realizes short-time and high-efficiency pyrolysis. In addition, Zn vapor also acts as a catalyst and has good catalytic effect on pyrolysis in the high temperature field, and the catalytic effect of Zn on liquid products (high additional products) is more obvious, and more liquid products can be produced by directional catalytic pyrolysis of the Zn catalyst. The Clapeyron equation is as follows:

[0045]

[0046] P is the external pressure, T is the boiling point temperature, L is the latent heat of vaporization of the substance, and V is the specific volume ratio between gas and liquid. The external pressure environment can change the boiling point of the substance.

[0047] Because the traditional pyrolysis furnace has a large heat loss in the process of converting electrical energy into heat energy, and the uniformity of material heating is greatly limited, the pyrolysis efficiency is usually only between 60%-80%, and the high latent heat of vaporization of high temperature Zn vapor of the embodiment of the present application has high heat conversion rate and high effective heating through uniform contact, so that the overall pyrolysis efficiency is improved by 2-3 times. At the same time, the generation of process by-products is reduced. Because of the instantaneous high temperature rise and a large amount of heat release, the heating speed is very fast and the catalytic effect makes the reaction process greatly improved, reduces incomplete cracking, reduces the generation of coke and unsaturated hydrocarbons and other by-products, and the high temperature pyrolysis reaction of Zn as a catalyst can enhance certain specific reaction paths in the pyrolysis process, so that the generated gas and liquid products are more pure, and the generation of 20%-40% low value by-products is reduced.

[0048] The embodiment of the present application focuses on the scheme of using solid matter as heat transfer medium to heat pyrolysis matter after vaporization. The selected solid matter (Zn) is as less reactive as possible with pyrolysis matter. Such solid matter can be well separated from product and waste after participating in pyrolysis. The selected solid matter can well cope with pyrolysis in high temperature range, aiming at the shortcoming that water vapor as latent heat heating medium can only pyrolyze at a lower temperature range. Zinc has a high boiling point (907℃) required for high temperature pyrolysis, and has the highest latent heat of vaporization (1996kJ / kg), close to water. Its heating capacity in high temperature field is very strong. Zinc can also catalyze the pyrolysis reaction of various plastics, increase the production of aromatic and cyclic hydrocarbons, and zinc is not as volatile and toxic as mercury, while sulfur and phosphorus will react with reaction products to contaminate the final product.

[0049] Specifically, the mechanism of action of zinc oxide and zinc is explained:

[0050] The main mechanism of action of ZnO is: (1) promoting the breaking of C-C bonds. In the pyrolysis process, the active sites on the surface of ZnO can interact with the carbon-carbon bonds in the polymer molecules, reducing the energy barrier of the cracking reaction. (2) Promote dehydrogenation reaction. ZnO promotes the dehydrogenation of polymers through redox sites (such as the dehydrogenation of polyethylene and polypropylene), forming unsaturated hydrocarbons (such as olefins). (3) Influence the product distribution, the Lewis acid sites on the surface of ZnO can adsorb and activate the hydrocarbon intermediates, promote the further cracking of carbon-hydrogen bonds, generate small molecule gas (such as hydrogen, methane) or liquid hydrocarbon. At the same time, the basic sites of ZnO can inhibit the generation of acidic by-products (such as CO2, HCl).

[0051] Catalytic effect of Zn and Zn / ZSM-5: After Zn is loaded on ZSM-5 molecular sieve, Zn / ZSM-5 composite catalyst exhibits unique synergistic catalytic effect: (1) Provide strong acid sites. ZSM-5 molecular sieve has a rich microporous structure and acid sites, which can adsorb and crack high molecular weight hydrocarbons. The introduction of Zn will enhance the acidity of the molecular sieve, further improve its cracking activity. (2) Zn has strong aromatization catalytic ability in aromatization reaction, which can convert plastic cracking products into aromatic hydrocarbons (such as benzene, toluene, xylene) through dehydrogenation and cyclization reaction. (3) Increase the production of hydrogen. The redox properties of Zn can promote the generation of hydrogen, especially in the pyrolysis reaction of polyethylene (PE) and polypropylene (PP).

[0052] ZSM-5 zeolite (ZSM-5 molecular sieve) is a new type of zeolite molecular sieve containing organic amine cation synthesized by the United States Mobil Company. Because it has many unique properties in chemical composition, crystal structure and physicochemical properties, it shows excellent catalytic efficiency in many organic catalytic reactions, and has been widely used in industry, becoming a promising new type of catalyst for petroleum and chemical industry.

[0053] ZSM-5 zeolite has high thermal stability. This is caused by the structural stability of the five-membered ring in the framework and the high silicon-aluminum ratio. For example, after calcining the sample at about 850℃ for 2 hours, the crystal structure does not change. It can even withstand high temperature of 1100℃. ZSM-5 is one of the highest thermal stability among known zeolites.

[0054] In some embodiments, the molecular sieve is selected from one or more of ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-12 molecular sieve, and Beta molecular sieve.

[0055] In some embodiments, the pore size of the molecular sieve is 0.51-0.56 nanometers.

[0056] In some embodiments, the molecular sieve is further loaded with 0.1-3g of zinc oxide.

[0057] By controlling the pore size of the molecular sieve, the amount of Zn vapor and pyrolysis product gas entering the molecular sieve is controlled, and thus the amount of final product is controlled; by controlling the amount of Zn loaded in the molecular sieve and adding a certain amount of zinc oxide to increase the boiling point, the loaded elemental Zn is not easy to vaporize.

[0058] It should be understood that the application of the present application is not limited to the above examples, and those skilled in the art can make improvements or changes according to the above description, and all these improvements and changes shall belong to the protection scope of the appended claims of the present application.

Claims

1. A rapid pyrolysis catalytic apparatus using latent heat of Zn vapor heating, characterized by, The pyrolysis catalytic device comprises a pyrolysis reaction furnace, a catalytic stick, and a pyrolysis reaction dish, the pyrolysis reaction furnace is internally provided with a pressure regulating valve, both ends of the pyrolysis reaction furnace are sealed by sealing flanges, and a superheated steam inlet and a pyrolysis product outlet are respectively formed in the sealing flanges at both ends of the pyrolysis reaction furnace; the catalytic stick is located inside the pyrolysis reaction furnace, one end of the catalytic stick is connected with the pyrolysis reaction dish, and the other end is connected with the sealing flange close to the superheated steam inlet; the pyrolysis catalytic device further comprises a pyrolysis product collecting device, which is connected with the pyrolysis reaction furnace through the pyrolysis product outlet and is used for collecting and processing pyrolysis products; The catalytic stick comprises a molecular sieve and a zinc catalyst loaded on the molecular sieve, and the pyrolysis reaction dish is a zinc oxide reaction dish; The pyrolysis product collecting device comprises a condenser, a liquid product collecting bottle, a gas washing bottle, and a gas collecting bag connected in sequence, and the condenser is connected with the pyrolysis reaction furnace through the pyrolysis product outlet; The catalytic stick is provided with a temperature measuring thermocouple and a gas pressure sensor, and the zinc oxide reaction dish is provided with a temperature measuring thermocouple and a gas pressure sensor; The molecular sieve is selected from one or more of ZSM-5 molecular sieve, ZSM-11 molecular sieve, ZSM-12 molecular sieve, and Beta molecular sieve.

2. The pyrolysis catalytic device of claim 1, wherein, The temperature measuring thermocouples are evenly arranged on the surface of the catalytic stick and the upper and lower surfaces of the zinc oxide reaction dish.

3. The pyrolysis catalytic device of claim 1, wherein, The pore size of the molecular sieve is 0.51-0.56 nm.

4. The pyrolysis catalytic device of claim 1, wherein, The molecular sieve is further loaded with 0.1-3 g of zinc oxide.

5. A pyrolysis catalytic process based on the pyrolysis catalytic apparatus according to any one of claims 1-4, characterized by, The method comprises the following steps: The pyrolysis material is placed in the zinc oxide reaction dish, inert gas is introduced into the superheated steam inlet, and the air in the pyrolysis catalytic device is exhausted; The pyrolysis reaction furnace is started, zinc vapor is prepared, and the pressure regulating valve is adjusted so that the pressure in the pyrolysis reaction furnace reaches the required pressure; The pyrolysis products are collected and processed at the pyrolysis product outlet.

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