Liquid-phase ammonia-related molten salt catalyst and application thereof

Abstract

The invention discloses a liquid-phase ammonia-related molten salt catalyst and application thereof. The liquid-phase ammonia-related molten salt catalyst is in a liquid state formed by heating and melting at least one substance component of metal halide, metal hydroxide or metal oxyacid, and is used for directly performing interface contact catalytic reaction with a gaseous reactant under reaction conditions. The liquid-phase ammonia-related molten salt catalyst has the advantages of low cost, high activity and high stability, and the catalytic efficiency of ammonia decomposition, ammonia synthesis, SCR denitration and other ammonia-related reactions can be improved.

Description

Technical Field

[0001] The present invention relates to the technical field of ammonia-related catalytic reactions, and in particular to a liquid-phase ammonia-related molten salt catalyst and applications thereof. Background Art

[0002] Ammonia is a key inorganic chemical product, with approximately 80% used in the production of chemical fertilizers and 20% as feedstock for other chemical products. Three chemical reactions involving ammonia are particularly important: ammonia synthesis, ammonia decomposition to produce hydrogen, and SCR-NH3 selective catalytic reduction denitrification technology.

[0003] Fertilizers made from synthetic ammonia can accelerate plant growth and increase yields, thereby improving crop production efficiency. More than half of global food production is directly related to synthetic ammonia fertilizer, helping to solve the world's food crisis. Synthetic ammonia is widely used in the chemical industry, for example, in the manufacture of nitric acid, various nitrogen-containing inorganic salts and organic intermediates, cellulose, sulfonamides, polyurethanes, polyamide fibers, nitrile rubber, explosives, dyes, and other products. Furthermore, the production of synthetic ammonia from syngas produces a large number of byproducts such as methanol and ethanol, which have promoted the development of chemical products and the national economy. The synthetic ammonia industry is considered the greatest chemical invention of the 20th century and is also known as the "Bellwether" reaction in heterogeneous catalysis. From a disciplinary perspective, it is even hailed as the most groundbreaking chemical reaction in human history. However, industrial ammonia synthesis currently still utilizes the Haber-Bosch (HB) process, which requires high temperature and high pressure (350-550°C, 10-30 MPa) and consumes 1%-2% of the global energy supply. It also emits approximately 500 million tons of carbon dioxide annually, accounting for approximately 1.8% of global CO2 emissions. Furthermore, BASF's century-old molten iron catalyst still dominates industrial production. Ruthenium catalysts, while highly active, are strongly inhibited by H2. Carbon-supported Ru catalysts undergo methanation under ammonia synthesis conditions, resulting in loss of the activated carbon support. Furthermore, Ru and Os are very expensive, and Ru / C catalysts offer limited energy savings. Therefore, the development of clean, efficient, and "green" ammonia synthesis catalytic systems is urgently needed to lower reaction temperatures, increase equilibrium ammonia conversion, improve reaction conditions, reduce power consumption, and enhance ammonia production efficiency.

[0004] Hydrogen is a highly efficient and clean energy source. However, its low bulk density and difficulty in liquefying present a series of technical obstacles to its storage and transportation. Ammonia is an excellent chemical hydrogen storage medium, with a high hydrogen content (17.75% by mass), easy liquefaction (0.8 MPa, 298K), easy storage and transportation, and no generation of harmful impurities such as COx. However, Ru-based catalysts used for ammonia decomposition to produce hydrogen are expensive and costly to use, despite their advantages such as high activity and stability at low temperatures. Non-precious metal catalysts such as Ni, Fe, and Co are inexpensive but have low activity and slow reaction rates. They are easily deactivated at high temperatures (650-750°C), resulting in high energy consumption. Therefore, the development of low-cost, highly active, and stable ammonia decomposition catalysts is imperative.

[0005] Nitrogen oxides (NO x ) is a common air pollutant that poses a great threat to human health and the ecological environment. It mainly comes from coal-fired boilers and motor vehicle exhaust emissions. Selective catalytic reduction (SCR) technology is a technology that reduces NO x An effective way to remove pollutants is to catalytically react nitrogen oxides in flue gas with a reducing agent (NH3-SCR) to produce N2 and H2O, thereby reducing or eliminating nitrogen oxide pollution to the atmospheric environment. This technology has no byproducts, no secondary pollution, a simple device structure, high removal efficiency (up to 90% or more), reliable operation, and easy maintenance. Currently, catalysts include precious metals, molecular sieves, and metal oxides. Among them, precious metal catalysts are relatively expensive, and molecular sieves have narrow pore sizes and high diffusion resistance. Vanadium-based metal oxide catalysts (such as V2O5-WO3 / TiO2) have a wide range of raw materials, simple preparation, and stable denitrification efficiencies exceeding 90%. They are widely used in industrial boiler (kiln) flue gas denitrification. However, the vanadium in vanadium-based catalysts is toxic; the catalyst has low low-temperature reaction activity; high-temperature applications in coal-fired and oil-fired applications face high-dust flue gas conditions, and the catalyst is easily clogged and covered, resulting in failure. Furthermore, water and sulfur resistance properties need to be improved.

[0006] The inventors of this application noticed that if a liquid catalyst is used for catalytic reaction by bubbling method, its catalytic area is relatively small (for example, the size of the bubbles can usually be controlled at 0.1-1 cm), while if a solid catalyst is used for catalytic reaction, the particle size of the catalyst can often achieve particles or micropores with a diameter of 10-100 nm. Therefore, the conventional liquid catalyst has weak catalytic properties, and coupled with its disadvantage in catalytic area, it has not been applied on a large scale in industry. On the other hand, most of the catalysts currently used for heterogeneous catalytic reactions use solid catalysts, and the atoms on the solid surface of the solid catalyst have a clear position, around which only small amplitude vibrations can occur, the surface has periodicity, and the active sites for dissociative adsorption are few and fixed. The inventors of this application recognize that liquid catalysts are mobile because the surface atoms are mobile and form many configurations with transient lifespans; in addition, liquid atoms have higher mobility and can undergo larger displacements to adapt to the bonding "needs" of dissociated fragments; therefore, liquid catalysts have more active sites, and solid catalysts are rapidly deactivated due to factors including carbon deposition (coking), while liquid catalysts can provide a constantly updated gas-liquid interface and an environment for continuously separating by-products (such as solid carbon), and are not easily deactivated. However, most of the currently available liquid catalysts are used in homogeneous catalytic reactions, and usually homogeneous catalytic reactions need to be carried out under solvent (water or organic reagent, etc.) conditions, which cannot meet the high temperature working environment (ammonia-related reactions) in this case. For example, liquid metal LM heterogeneous catalysts and molten salt catalysts that can work at high temperatures are usually used in small-scale experiments. The most common bubbling method has a small catalytic area, with the bubble size usually being 0.1-1 cm (4-6 orders of magnitude larger than conventional solid catalysts, which can often achieve particles or micropores with a diameter of 10-100 nm). General liquid metal and alloy catalysts and molten salt catalysts have insufficient activity and are difficult to overcome the huge gap in catalytic area. Therefore, the currently available liquid heterogeneous catalysts cannot be used in many chemical reactions, especially for ammonia-related reactions. There are currently few research reports on the use of liquid-phase catalysts.

[0007] Therefore, developing a liquid catalyst for heterogeneous catalysis that can achieve high activity for the above-mentioned ammonia-related chemical reactions is a major challenge. Summary of the Invention

[0008] According to one embodiment of the present invention, the purpose is to provide a liquid-phase ammonia-related molten salt catalyst with high activity and its application to improve the catalytic efficiency of ammonia-related reactions such as ammonia decomposition, ammonia synthesis, and SCR denitrification.

[0009] The above purpose can be achieved by implementing the following technical solutions:

[0010] According to one aspect of the present invention, a liquid-phase ammonia-related molten salt catalyst is provided. The liquid-phase ammonia-related molten salt catalyst is a liquid formed by heating and melting using at least one material component selected from metal halides, metal hydroxides or metal oxygen-containing acids, and is used for direct interfacial contact catalytic reaction with gaseous reactants under reaction conditions.

[0011] Optionally, the metal in the metal halide, metal hydroxide and metal oxyacid is one of a transition metal, an alkali metal and an alkaline earth metal.

[0012] Optionally, the liquid-phase ammonia-related molten salt catalyst is in liquid form by using at least one material component of a metal halide and melting it by heating.

[0013] Optionally, the liquid-phase ammonia-related molten salt catalyst uses at least three material components, each material component is selected from metal halides, in each metal halide, the metal is one of the transition metals manganese, iron, and ruthenium, and the halide is one of chloride and bromide.

[0014] According to one aspect of the present invention, there is also provided an application of a liquid-phase ammonia-related molten salt catalyst, which is applied to any one of the reactions of ammonia decomposition, ammonia synthesis and SCR denitrification; wherein, during application, under reaction conditions, the gaseous reactants and the liquid-phase ammonia-related molten salt catalyst come into interfacial contact to produce a catalytic reaction, and part of the products and unreacted products are separated from the catalyst.

[0015] Alternatively, during application, a liquid-phase ammonia-related molten salt catalyst, formed by heating and melting, is pre-introduced into a reaction vessel. The reaction raw materials are then introduced into the reaction vessel from the bottom, causing the reactants to rise as bubbles. Under the reaction conditions, the gaseous reactants come into interfacial contact with the liquid-phase ammonia-related molten salt catalyst, resulting in a catalytic reaction. Furthermore, after the reaction raw materials are introduced into the reaction vessel, they are allowed to remain in the reaction vessel for a predetermined period of time to allow them to rise as bubbles.

[0016] Optionally, when used, the liquid-phase ammonia-related molten salt catalyst reacts with the gaseous reactants in the form of liquid droplets.

[0017] Optionally, the average diameter of the droplets is less than 0.1 mm, which is achieved by any one of methods 1, 2, 3, and 4; wherein,

[0018] Method 1 is to use an atomizing device to atomize the liquid phase ammonia molten salt catalyst formed by heating and melting into droplets, so that the gaseous reactants react with the droplets;

[0019] Method 2 is to evaporate and condense the liquid ammonia molten salt catalyst placed in the reaction vessel to form droplets by heating, evaporation and recondensation, so that the gaseous reactants introduced into the area where the droplets are located react with the droplets;

[0020] Method three is to pre-load the material components of the liquid-phase ammonia-related molten salt catalyst on the surface of a solid support and spray it into the reactor or pre-fill it into a fixed bed reactor. Under reaction conditions, the material components loaded on the surface of the solid support are heated and melted into droplets, so that the gas reactant flows through the support and fully contacts and reacts with the droplets on the support;

[0021] Method 4: First, the material components of the liquid-phase ammonia-related molten salt catalyst are prepared into ultrafine powders, and the ultrafine powders are heated into liquid droplets under reaction conditions, and reacted with gaseous reactants.

[0022] Optionally, when used, the method further includes: collecting the falling liquid droplets, removing impurities, and reusing the catalyst obtained after the impurities removal.

[0023] Optionally, when applied to ammonia decomposition reaction, the reaction temperature is 500-1500°C; the reaction raw material is NH3, and the products are H2 and N2; and the products H2 and N2 and unreacted NH3 float to the liquid surface and are separated from the liquid phase ammonia molten salt catalyst.

[0024] Optionally, when applied to the reaction of synthesizing ammonia, the reaction temperature is 400-1000°C, the reaction pressure is 0.1-50MPa; the reaction raw materials are a mixture of H2 and N2, and the product is NH3; and the product NH3 and unreacted H2 and N2 float to the liquid surface and are separated from the liquid phase ammonia-related molten salt catalyst.

[0025] Optionally, when applied to the SCR denitrification reaction, the reaction temperature is 280-1200°C; the reaction raw materials are NH3 and NO-containing reaction gas; the gaseous products and unreacted products after the reaction float to the liquid surface and are discharged after treatment.

[0026] Optionally, when applied to the SCR denitrification reaction, the reaction temperature is 280-1200°C; NH3 and liquid ammonia molten salt catalyst droplets are sprayed together into the flue gas containing NO reaction raw gas in the reaction container; gaseous products and unreacted products float to the liquid surface and are discharged after treatment.

[0027] Beneficial effects: Compared with the prior art, the embodiments of the present invention have the following advantages:

[0028] 1. This invention utilizes a low-cost, scalable, high-quality liquid-phase ammonia-related molten salt catalyst (LCs-NH3) to achieve efficient ammonia synthesis, ammonia decomposition, and SCR-NH3 selective catalytic reduction denitration reactions. The "ammonia-related" in the liquid-phase ammonia-related molten salt catalyst primarily refers to ammonia synthesis, ammonia decomposition, and SCR-NH3 selective catalytic reduction denitration reactions.

[0029] 2. The catalyst uses cheap common inorganic salts, and the preparation method relies on melting. The method is simple, the quality is uniform and controllable, and the preparation cost is low.

[0030] 3. Liquid-phase ammonia molten salt catalysts (LCs-NH3) are highly active and efficient. In particular, their efficiency in synthesizing ammonia is better than that of traditional molten iron catalysts and expensive ruthenium catalysts.

[0031] 4. Liquid-phase ammonia molten salt catalyst (LCs-NH3) has high stability and is not easy to deactivate and poison. In addition, it can also adapt to harsh working conditions, especially for catalytic denitrification. Most existing denitrification processes use low-temperature denitrification after dust removal. At this time, the Ru catalyst is expensive and not very active. For example, a high-temperature denitrification followed by a low-temperature dust removal process is used. However, this inevitably leads to the denitrification catalyst being in a high-concentration dust and flue gas working condition for a long time. Flue gas dust is an important cause of catalyst wear, clogging, and poisoning, thereby shortening the catalyst life, reducing denitrification efficiency, and increasing operating costs. The liquid-phase ammonia molten salt catalyst of the present invention has high stability, is not easy to deactivate, and is not easy to poison. In particular, in an optional embodiment of the present invention, a droplet-related ammonia catalyst is directly sprayed into the flue gas with ammonia (or the flue gas is bubbled from the bottom of the liquid-phase catalyst). The use process can withstand high temperature, high dust, and high ash, does not affect the catalytic activity, and can also resist the poisoning of sulfur oxides, so it can be arranged in the high-temperature section before dust removal. Moreover, the catalyst after the reaction of the present invention is easy to separate from the solid by-products, and has many advantages compared with the existing SCR-NH3 denitrification catalyst.

[0032] 5. The present invention's liquid-phase ammonia-containing molten salt catalyst (LCs-NH3) is a multicomponent mixture (i.e., a mixture of multiple components), leveraging the synergistic catalytic effects of these components. Compared to existing single-component liquid catalysts, such as molten iron catalysts, the present invention's liquid-phase ammonia-containing molten salt catalyst can operate at lower temperatures.

[0033] 6. The present invention is reliable and environmentally friendly in the entire process chain of catalyst processing, use, recovery and heterogeneous catalytic reaction process.

[0034] In summary, the liquid-phase ammonia-related molten salt catalyst (LCs-NH3) of the present invention can realize efficient ammonia synthesis, ammonia decomposition and SCR-NH3 selective catalytic reduction denitrification reaction, and the catalyst has excellent performance, low preparation cost, large output, can be prepared on a large scale, has high catalytic activity and efficiency, good stability, is not easy to deactivate and poison, the active substances can be combined and adjusted, the loading amount is controllable, the application process is simple and convenient, and the overall cost is low. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] Figure 1 It is a schematic diagram of the principle of the catalytic reaction of a liquid-phase ammonia-related molten salt catalyst in one embodiment of the present invention.

[0036] Figure 2Schematic diagram of the principle of droplet formation of a liquid-phase ammonia-related molten salt catalyst in one embodiment of the present invention.

[0037] Figure 3 Schematic diagram of the principle of a liquid-phase ammonia-related molten salt catalyst reacting in the form of droplets in one embodiment of the present invention.

[0038] Figure 4 It is a schematic diagram of the application process of the liquid-phase ammonia-related molten salt catalyst in one embodiment of the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions of the present invention. Obviously, the embodiments described are only some embodiments of the present invention, rather than all embodiments. The following description of at least one exemplary embodiment is actually only illustrative and is in no way intended to limit the present invention and its application or use. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0040] The present invention provides a liquid-phase ammonia-related molten salt catalyst, which is a liquid formed by heating and melting at least one material component of a metal halide, a metal hydroxide or a metal oxyacid, and is used for directly performing an interfacial contact catalytic reaction with a gaseous reactant under reaction conditions. The liquid-phase ammonia-related molten salt catalyst is liquid under reaction conditions, and has the advantages of low preparation cost, simple preparation method, high activity, good stability, and not easy to deactivate and poison. The liquid-phase ammonia-related molten salt catalyst is used to carry out ammonia-related reactions such as ammonia decomposition, ammonia synthesis or SCR denitrification, which can improve the catalytic efficiency of the reaction. In addition, the active substances of the catalyst can be combined and adjusted, and the loading amount can be controlled, which increases the wide range of applications.

[0041] The metal halide, metal hydroxide, and metal oxyacid are each selected from the group consisting of a transition metal, an alkali metal, and an alkaline earth metal. Examples of the metal oxyacid include Fe2(SO4)3. The transition metal is preferably manganese, iron, or ruthenium. The alkali metal is preferably lithium or potassium. The alkaline earth metal is preferably magnesium or calcium.

[0042] In a preferred embodiment, the liquid-phase ammonia-related molten salt catalyst is a liquid formed by heating and melting at least one substance component of a metal halide. In this embodiment, the liquid-phase ammonia-related molten salt catalyst formed by a metal halide has higher stability and can provide a more suitable reaction environment, which is more conducive to the conduct of ammonia-related reactions. Among them, compared with alkaline metal hydroxides, halides are neutral compounds and are more beneficial for ammonia-related reactions such as ammonia synthesis; compared with oxygen-containing acids, halides are more stable and less likely to produce by-products. For example, metal oxygen-containing acids decompose at high temperatures to generate high-melting-point acid anhydrides.

[0043] In a preferred embodiment, the liquid-phase ammonia-related molten salt catalyst is composed of at least three material components, each of which is selected from metal halides. In each metal halide, the metal is one of the transition metals manganese, iron, and ruthenium, and the halide is one of chloride and bromide. In this embodiment, a liquid-phase ammonia-related molten salt catalyst is formed by using at least three material components in the metal halide to form a liquid mixed molten salt. On the one hand, the synergistic catalytic advantages of each component element can be brought into play; for example, the chlorides of Mn and Li are more active towards N and H, respectively, when synthesizing ammonia, and the reaction efficiency is higher; on the other hand, the mixed salt also lowers the melting point of the catalyst, which is more conducive to catalytic reaction under good reaction conditions and reduces the requirements for catalytic reaction conditions. For example, the catalytic reaction temperature can be lowered, and the equipment and process can be simplified.

[0044] The present invention provides an application of the liquid-phase ammonia-related molten salt catalyst for use in any of the reactions of ammonia decomposition, ammonia synthesis, and SCR denitrification. During application, under reaction conditions, gaseous reactants and the liquid-phase ammonia-related molten salt catalyst come into interfacial contact to produce a catalytic reaction, and some products and unreacted products are separated from the catalyst.

[0045] In an optional embodiment, the liquid phase ammonia molten salt catalyst is first introduced into the reaction vessel, and the gaseous reactants float up in the form of bubbles to react with it. Figure 4 As shown, the liquid phase ammonia molten salt catalyst is first introduced into the reaction vessel; then the reaction raw materials are introduced into the reaction vessel from the bottom of the reaction vessel, and stay for a period of time, and the reactants float up in the form of bubbles; then, under the reaction conditions, the gaseous reactants are brought into interfacial contact with the pre-introduced liquid phase ammonia molten salt catalyst to cause a catalytic reaction, and after the reaction, part of the product and the unreacted product will be effectively separated from the catalyst due to the density difference.

[0046] In another optional embodiment, the liquid-phase ammonia-related molten salt catalyst reacts with the gaseous reactants in the form of droplets. Carrying out a heterogeneous catalytic reaction in the form of droplets not only increases the catalytic surface area but, more importantly, improves the stability of the catalyst, avoiding deactivation and poisoning during the reaction, further expanding its scope of application. Furthermore, this method can also include collecting and removing impurities from the falling droplets, and reusing the resulting catalyst, thereby further reducing catalyst costs.

[0047] In addition, based on the high activity of the liquid-phase ammonia-related molten salt catalyst of the present invention, the diameter of the droplets is controlled to be less than 0.1 mm. Further, any one of the following methods 1, 2, 3, and 4 of the present invention can be used to achieve this.

[0048] Method 1 is to use an atomizing device to atomize the liquid phase ammonia molten salt catalyst formed by heating and melting into droplets, so that the droplets react with the gaseous reactants.

[0049] The second method is to evaporate and condense the liquid-phase ammonia molten salt catalyst placed in the reaction vessel to form droplets by heating, evaporating and recondensing; so that the gaseous reactants introduced into the area where the droplets are located react with the droplets.

[0050] Method three is to pre-load the material components of the liquid-phase ammonia-related molten salt catalyst on the surface of a solid carrier and pre-fill it in a fixed bed reactor. Under reaction conditions, the material components loaded on the surface of the solid carrier are heated and melted into droplets, so that the gas reactant flows through the carrier and fully contacts and reacts with the droplets on the carrier.

[0051] Method four, first prepare the material components of the liquid-phase ammonia molten salt catalyst into ultrafine powder, and under the reaction conditions, heat the ultrafine powder into droplets under the reaction conditions, and react with the gaseous reactants. Exemplarily, the method for prefabricating the catalyst ultrafine powder can be prefabricated by a liquid-phase ammonia molten salt catalyst using a rapid cooling method after atomization, electron beam rapid cooling quenching, laser surface melting, mechanical crushing, etc. In addition, the atomization method can adopt pressurized atomization, dual-flow (air flow or liquid flow / liquid flow) atomization, ultrasonic atomization, centrifugal atomization, etc. Mechanical crushing can be crushed by grinding equipment such as air flow mill, high-speed mechanical impact mill, vibration mill, stirred mill, ball mill, sand mill, cyclone mill, high-pressure roller (roller) mill, high-pressure water jet mill, etc., or it can be crushed by high-pressure homogenization, ultrafine shearing, ultrasonic crushing, etc.

[0052] The above optional embodiments of the present invention can all be used for ammonia decomposition, ammonia synthesis and SCR denitrification reactions.

[0053] In an optional embodiment, the liquid-phase ammonia-related molten salt catalyst is used in ammonia decomposition reaction, wherein the reaction temperature is 500-1500°C, preferably, the reaction temperature is 650-1000°C.

[0054] In the first embodiment, the raw NH3 reactant is introduced into the bottom of a reaction vessel containing a pre-prepared liquid-phase ammonia-containing molten salt catalyst. The gaseous reactants rise as bubbles and come into interfacial contact with the liquid catalyst, causing a catalytic reaction. The resulting H2, N2, and unreacted NH3 float to the surface and are separated from the liquid-phase ammonia-containing molten salt catalyst.

[0055] When the second embodiment (i.e., droplets) is adopted, any one of Method 1 and Method 4 is used to fill the reaction vessel with a droplet-type liquid-phase ammonia-related molten salt catalyst, and at the same time, the reaction raw materials are introduced from the bottom of the reaction vessel, and the gaseous reactants in the area where the droplets are located react with the droplets.

[0056] In an optional embodiment, the liquid-phase ammonia-related molten salt catalyst is used in ammonia synthesis reaction, wherein the reaction temperature is 300-1000°C and the reaction pressure is 0.1-50 MPa; more preferably, the reaction temperature is 300-750°C.

[0057] When the first embodiment is adopted, the reaction raw materials H2 and N2 are mixed and introduced from the bottom of the reaction vessel. The reaction vessel is pre-filled with the prepared liquid-phase ammonia-related molten salt catalyst. The gaseous reactants float up in the form of bubbles and come into interfacial contact with the liquid catalyst to cause a catalytic reaction. The product NH3 and unreacted H2 and N2 float to the liquid surface and are separated from the liquid-phase ammonia-related molten salt catalyst.

[0058] When the second embodiment (i.e., droplets) is adopted, the reaction vessel is filled with a droplet-type liquid-phase ammonia-related molten salt catalyst using any one of methods one and four, the reaction raw materials are introduced from the bottom of the reaction vessel, and the gaseous reactants in the area where the droplets are located react with the droplets.

[0059] In an optional embodiment, the liquid-phase ammonia-related molten salt catalyst is used in an SCR denitration reaction, wherein the reaction temperature is 280-1200°C, and more preferably, the reaction temperature is 280-900°C.

[0060] When the first embodiment is adopted, NH3 and NO-containing reaction raw gas are introduced from the bottom of the reaction vessel. The reaction vessel is pre-filled with the prepared liquid ammonia molten salt catalyst. The gaseous reactants float up in the form of bubbles and come into interfacial contact with the liquid catalyst to produce a catalytic reaction. The gaseous products and unreacted products float to the surface of the liquid and are discharged after treatment.

[0061] When the second embodiment is employed, one method involves introducing NH3 and a NO-containing reaction feed gas into a reaction vessel filled with a droplet-type, liquid-phase, ammonia-related molten salt catalyst, LdCs-NH3, and allowing the reaction to remain for a period of time. Under reaction conditions, the reactants and the catalyst come into interfacial contact, generating a catalytic reaction. The gaseous products and unreacted materials float to the surface and are subsequently processed and discharged. Another method involves spraying NH3 and a droplet-type, liquid-phase, ammonia-related molten salt catalyst, LdCs-NH3, into flue gas containing the NO-containing reaction feed gas. Under reaction conditions, the reactants and the catalyst come into interfacial contact, generating a catalytic reaction. The gaseous products and unreacted materials float to the surface and are subsequently processed and discharged.

[0062] The following is a further description of the implementation methods of this application with reference to specific examples:

[0063] Example 1 (Pre-addition of liquid-phase ammonia-related molten salt catalyst)

[0064] The catalytic device used in the catalytic reaction experiment of the present invention primarily comprises a reaction vessel, a heating device for heating the reaction vessel, a detection device connected to the reaction vessel, and a reactant introduction device. Other supporting devices may also be included, such as an auxiliary heating device, a temperature detection device such as a multi-point thermocouple, and thermal insulation devices such as insulating quartz beads and quartz sand.

[0065] Wherein, checking device can include online mass spectrometer and online gas chromatographic detection instrument, reactant introduction device includes quartz air guide tube, quartz air guide tube stretches into main reactor (specifically stretching into length according to bubble column length when reaction is determined), by quartz air guide tube, reactant gas is imported in main reactor, to react with the catalyst in main reactor.Heating unit can use vertical tube furnace, and reaction vessel can be stainless steel crucible or stainless steel outer sleeve+quartz crucible, and wherein quartz crucible is main reactor.When quartz crucible is as main reactor, stainless steel sleeve can prevent quartz from cracking the potential safety hazard brought by alloy leakage when high temperature, can eliminate the interference that metal container participates in catalysis, and the inertness of quartz is not substantially related to ammonia molten salt catalyst reaction with the metal inorganic salt liquid phase selected by the present embodiment.

[0066] Unless otherwise specified, the main reactor is a stainless steel crucible with a reactor diameter ID = 15 mm. Multiple reactors are mounted on a support, enabling simultaneous catalytic experiments with 1-10 different catalyst formulations. The support is placed in a vertical tubular furnace with multi-stage controlled heating, and the bottom of the support is supported and insulated by ceramic insulation.

[0067] Reactions were conducted in separate bubble columns, with the length of the bubble column measured from the gas bubbling point at the crucible bottom to the top of the constant-temperature heating zone. Thermal insulation at the upper and lower ends of the constant-temperature heating zone in the tubular furnace heating zone was provided by multiple layers of insulation, such as mica and asbestos, placed on the top of the crucible, and ceramic insulation at the bottom of the crucible. A 30mm thick alloy melt, intersecting the insulation barrier, outside the heating zone minimized headspace heat. The crucible outside the insulation barrier was exposed to air and maintained cool by an external fan. The reactor headspace effect above the melt surface was further corrected using reaction data from selected inert metals. K-type thermocouples inserted into the melt measured the melt temperature in real time at multiple points during heating, holding, and bubbling reactions.

[0068] The mixed gas is introduced into the reactor from above through a fine quartz tube via a pipeline using a gas mass flow meter MFC, and analyzed by an online mass spectrometer MS and a gas chromatograph GC.

[0069] The schematic diagram of the experimental device is attached. Figure 1 .

[0070] Ammonia decomposition reaction.

[0071] Before the start of the catalytic experiment, the components were loaded into a quartz crucible according to the formula and the loading amount, and the temperature was raised to 950°C in stages and kept warm for 4 hours. Ar gas was kept purged to obtain a liquid-phase ammonia-related molten salt catalyst LCs-NH3 melt, and the melt was cooled to the reaction temperature.

[0072] 1) Formulations: MnCl2, 15MnCl2-30LiCl-55KCl, 18MnCl2-44KCl-38LiCl, LiCl, and comparative element Sn. The reaction pressure was set at 0.1 MPa, using the above-described experimental apparatus. After purging and pretreatment, a 30 sccm mixture of NH3 (feed ratio 32% NH3, 68% Ar) was introduced as the reaction raw material. The catalytic performance of each catalyst at reaction temperatures of 900°C and 950°C was examined in a 160 mm bubble column. The conversion rates are shown in Table 1 below:

[0073] Table 1 Ammonia decomposition conversion rate of each catalyst at different temperatures

[0074] Temperature formula Ammonia decomposition conversion rate % 900 <![CDATA[MnCl2]]> 3.6 900 <![CDATA[15MnCl2-30LiCl-55KCl]]> 6.1 900 <![CDATA[18MnCl2-44KCl-38LiCl]]> 6.6 900 LiCl 2.5 900 Sn 1.70 950 <![CDATA[MnCl2]]> 4.2 950 <![CDATA[15MnCl2-30LiCl-55KCl]]> 6.8 950 <![CDATA[18MnCl2-44KCl-38LiCl]]> 7.0 950 LiCl 3.7 950 Sn 3.1

[0075] 2) At a reaction temperature of 600°C, with other conditions unchanged, plasma-assisted activation of the feed gas at 8000V was used. The feed ratio was 67% NH₃ and 33% Ar, and the ammonia decomposition conversion rate of 18MnCl₂-44KCl-38LiCl was 8.4%. This indicates that plasma-assisted activation of the feed gas at 8000V improves catalytic efficiency at lower temperatures.

[0076] 3) Catalyst formulation: 18MnCl2-44KCl-38LiCl, pressure 0.1MPa, experimental apparatus changed to ID=180mm graphite crucible, raw gas NH3 was supplied from the bottom through a ceramic aeration plate (aeration plate diameter 150mm, micropore diameter ~10um), gas flow rate 12SLM, and the catalytic performance of each catalyst was investigated in a 100mm bubble column at reaction temperatures of 950°C, 850°C, and 750°C. The conversion rates were 25%, 9%, and 2.3%, respectively, within the error range. Other aspects are similar to 1). It can be seen that compared with the catalytic effect of the aforementioned pore ID=2mm vent tube, the catalytic efficiency of this embodiment using aeration plates with micropore diameters of ~10um was greatly improved, and the reaction temperature was further reduced, reflecting the rapid improvement in catalytic efficiency after the catalytic area was increased.

[0077] Comparative Example 1:

[0078] Wu Xiaoman, Li Xuefeng, Zhang Hongbin. Preparation of Ruthenium / Carbon Nanotubes by Liquid Phase Reduction and Their Catalytic Performance for Ammonia Decomposition. Precious Metals, Vol. 31, No. 3, August 2010, pp. 1-6.

[0079] Ru / CNTs were prepared using the impregnation method and the ethylene glycol liquid-phase reduction deposition method, respectively. The specific steps are as follows: ① 0.7067g of RuCl3·H2O (≥35%) was loaded onto 0.5000g of purified CNTs using an isochoric impregnation method in acetone (or water). After drying, the mixture was treated at 673K ​​under a stream of pure H2 for 4 hours to obtain x% Ru / CNTs (w). ② 0.2440mg of RuCl3·H2O was dissolved in 50ml of ethylene glycol. 1.700g of CNTs was then added to the ruthenium-ethylene glycol solution to form a uniform suspension. The suspension was then heated to 433K under reflux in an oil bath with stirring until the solution turned light yellow-brown. The solution was immediately removed, cooled, and the solid fraction was filtered and washed with deionized water to obtain x% Ru / CNTs (oh). The optimal range of x% was 3-6%, with 4.2% being the preferred value. 873K, space velocity GHSV = 30000 mL / h·g, 4.2% Ru / CNTs(OH) ammonia decomposition conversion rate 98%.

[0080] Cost comparison:

[0081] In Comparative Example 1, based on the ruthenium price of 110 yuan / g, the material cost of the 4.2% ruthenium component of the catalyst is 4,620 yuan / kg, and considering the preparation cost, it is 6,600 yuan / kg; the material cost of 18MnCl2-44KCl-38LiCl in this embodiment is less than 100 yuan / kg, and considering the melt preparation, the direct cost is less than one percent of that of the Ru / CNTs catalyst.

[0082] As mentioned above, the raw material price of the mixed salt is less than 100 / kg, which is one tenth of that of the precious metal dehydrogenation catalyst, and the total cost of melt preparation is ∼120 / kg.

[0083] The experimental results using aeration plates in 3) of Example 1, taking into account 10% annual catalyst depreciation and 300 days of annual production, yielded ~6,000g of hydrogen per catalyst unit. Comparative Example 1 achieved a product / mass catalytic efficiency of ~4g of hydrogen / g catalyst / hour. With 300 days of annual production, a conventional catalyst life of 6 months, two replacements, and a precious metal recycling and regeneration factor of 0.5, plus recycling costs, yielded a total annual maintenance cost of 10 yuan / g. This yielded 28.8kg of hydrogen per gram of catalyst per year, resulting in a hydrogen production of 2,880g per catalyst unit. This embodiment is twice as cost-effective as Comparative Example 1.

[0084] Figure 3 Schematic diagram showing the principle of the experimental device for the reaction of liquid-phase ammonia molten salt catalyst in the form of droplets. Figure 2 The schematic diagram of the principle of the droplet formation device is shown schematically.

[0085] like Figure 3As shown, the catalytic device also includes a liquid phase ammonia molten salt catalyst preparation device and a droplet forming device. Figure 2 As shown, the droplet forming device can adopt one of the following: a. double (gas) flow atomization structure, b. high pressure Laval nozzle, c. double roller centrifugal atomization. Double (gas) flow atomization structure means that the melt and high pressure gas enter from the central channel and the channel located on the periphery of the central channel respectively and then spray out to form droplets. High pressure Laval nozzle means that the melt and high pressure gas enter from the central channel and the channel located on the periphery of the central channel respectively and then spray out to form droplets. Figure 1 The specific structure shown (the channel diameter first decreases and then increases) allows the melt to enter the channel, forming droplets. Twin-roller centrifugal atomization involves two rollers rotating at high speeds in opposite directions, with the melt entering through the channel between the rollers to form droplets. Alternatively, centrifugal atomization involves the melt dripping onto a high-speed rotating disc due to gravity. Centrifugal force then throws the melt outward, forming droplets. This reaction occurs in the atomization zone outside the cylinder.

[0086] In the following embodiment 2, the liquid-phase ammonia-related molten salt catalyst preparation device is a high-pressure autoclave, and a graphite molten pool is provided in the high-pressure autoclave for alloy smelting. A high-pressure gas bottle is connected to the high-pressure autoclave to pressurize the interior of the autoclave. The outlet of the graphite molten pool is connected to the reaction device through a pipeline, and a droplet forming device is provided at the end of the pipeline, and the droplet forming device adopts a dual (gas) flow atomizing nozzle.

[0087] Example 2 (heating and melting into liquid state, then atomizing into droplets and introducing into reaction container)

[0088] SCR-NH3 denitrification reaction:

[0089] Before the catalytic experiment began, the catalyst components were loaded into a graphite melt according to the recipe. The temperature was then raised in stages to 800°C and held for 4 hours while maintaining an Ar gas purge. The melt was then reduced with hydrogen to a catalyst melt, which was then cooled to the reaction temperature. The melt was then placed in an autoclave with a maximum operating pressure of 8 MPa and equipped with an atomizing nozzle.

[0090] Reactions were conducted in quartz crucibles with total lengths of 800, 1200, and 1600 mm, respectively. Unless otherwise specified, the reactor diameter (ID) was 25 mm, and the quartz crucible length was 1200 mm. Catalyst droplets from the molten pool were sprayed into the crucible from the top. Simultaneously, a mass flowmeter (MFC) was used to introduce the mixed feed gases from above through a pipeline via a thin quartz tube to the measured temperature point within the crucible's reaction zone. The length of the reaction zone coincided with the length of the constant-temperature heating zone, which was insulated by the upper and lower ends of a tubular furnace heating zone (effective lengths of 400, 800, and 1200 mm) and by multiple layers of insulation, such as mica, ceramic, and asbestos, at the top and bottom of the crucible (lengths of 150 mm and 250 mm, respectively). Outside the insulation layer, the crucible's top and bottom were exposed to air and kept cool by an external fan to minimize the effects of pure headspace heat reactions. Headspace effects were further corrected using reaction data from selected inert metals. The K-type thermocouple in the crucible measures the temperature at multiple points in real time during the reaction.

[0091] The analysis was performed using an online mass spectrometer (MS) and a gas chromatograph (GC).

[0092] Catalyst formulation: 18MnCl2-44KCl-38LiCl. The quartz crucible is 1600mm long. Catalyst droplets are formed by atomizing a melt drawn from a 0.8MPa high-pressure molten pool with 0.4MPa high-pressure nitrogen gas through an atomizing nozzle. Calculations and prior laser reflection measurements indicate an average droplet size of 20µm. The injection rate is 40mg / min. The top diameter is increased to allow for horizontal spraying from the nozzle. The high-pressure nitrogen flow forms a swirling flow. A mixture of 10sccm NH3, 10sccm NO, and 80sccm Ar, the reaction raw materials, is introduced into the reaction zone at the measured temperature point at 580°C. The NO conversion rate is 51%.

[0093] Catalyst formula: Fe2(SO4)3, other conditions are the same as above. After testing, its NO conversion rate is 33%.

[0094] Catalyst formula: NaOH-KOH (1:1) mixed salt, other conditions are the same as above. After testing, its NO conversion rate is 30%, but it helps desulfurize sulfur-containing smoke and can play a comprehensive role.

[0095] Example 3

[0096] Ammonia synthesis reaction.

[0097] Before the catalytic experiment began, the liquid phase ammonia molten salt catalyst LCs-NH3 was prepared first.

[0098] The formulas of the mixed salt liquid phase ammonia molten salt catalyst are: 15MnCl2-30LiCl-55KCl, 18MnCl2-44KCl-38LiCl, 18MnCl2-44KBr-38LiCl, 52MgCl2-48CaCl2, which are directly heated to the reaction temperature and stabilized.

[0099] 1) Using a quartz crucible, the above-mentioned mixed salt formula was loaded into the crucible at a loading amount sufficient to achieve a liquid column length of 30 cm. Catalytic reactions were performed at atmospheric pressure, 450°C and 500°C, with a reaction gas flow rate of 30 sccm and an N:H ratio of 1:3.17.

[0100] The results are shown in Table 2 below:

[0101] Table 2 Synthetic ammonia yield of each catalyst at different temperatures

[0102] Temperature formula Synthetic ammonia yield% 450 <![CDATA[15MnCl2-30LiCl-55KCl]]> 0.37 450 <![CDATA[18MnCl2-44KCl-38LiCl]]> 0.39 450 <![CDATA[18MnCl2-44KBr-38LiCl]]> 0.33 500 <![CDATA[15MnCl2-30LiCl-55KCl]]> 0.38 500 <![CDATA[18MnCl2-44KCl-38LiCl]]> 0.41 650 <![CDATA[52MgCl2-48CaCl2]]> 0.10

[0103] 2) Using a micro-high-pressure reactor, the aforementioned 15MnCl2-30LiCl-55KCl salt mixture was loaded into a crucible, with a liquid column length of 30cm. Catalytic reactions were performed at 450°C, a reaction gas flow rate of 30sccm, and an N:H ratio of 1:3.17. Pressures were applied at 0.1, 1, and 5MPa, respectively; and at 370°C at 10MPa. The results are shown in Table 3 below:

[0104] Table 3 Synthetic ammonia yield of the catalyst under different conditions

[0105] Temperature Pressure MPa Synthetic ammonia yield% 450 0.1 0.37 450 1 1.94 450 5 2.93 370 10 4.5

[0106] 3) The catalytic device described in Example 2 is used to form droplets and a liquid-phase ammonia-related molten salt catalyst in the form of a mixed salt.

[0107] Ammonia synthesis was performed using a quartz crucible at atmospheric pressures of 450°C and 500°C, with a reaction gas flow rate of 30 sccm and an N:H ratio of 1:3.17. A molten salt mixture of 15MnCl2-30LiCl-55KCl and 18MnCl2-44KCl-38LiCl were drawn from a 0.2MPa high-pressure melt pool and centrifugally atomized to form droplets. Calculations and prior laser reflection measurements showed an average droplet size of 60 μm, and the injection rate was 50 mg / min. The results are shown in Table 4 below:

[0108] Table 4 Synthetic ammonia yield of various droplet-type catalysts at different temperatures

[0109] Temperature formula Synthetic ammonia yield% 450 <![CDATA[15MnCl2-30LiCl-55KCl]]> 0.88 450 <![CDATA[18MnCl2-44KCl-38LiCl]]> 0.93 500 <![CDATA[15MnCl2-30LiCl-55KCl]]> 0.71 500 <![CDATA[18MnCl2-44KCl-38LiCl]]> 0.79

[0110] 4) Activated alumina loaded with 18MnCl2-38LiCl-44KCl mixed salt, fixed bed reactor.

[0111] The mixed salt catalyst components, MnCl2, LiCl, and KCl, were dissolved in water according to the stoichiometric ratio to form a 0.3% dilute solution. 5% HCl was then added. The solution was ultrasonically shaken for 60 minutes. The dilute hydrochloride solution was then added dropwise to an equal mass of activated alumina (Al2O3) solid support and stirred uniformly for wet impregnation. The sample was sealed and allowed to stand for 24 hours. The mixture was then dried in a vacuum oven at 105°C for 24 hours and ground uniformly in a mortar to obtain a mixed salt catalyst (15MnCl2-30LiCl-55KCl / Al2O3) supported on an activated alumina solid support. The solution was then stored in a sealed, dry place in a storage tank.

[0112] The continuous micro-fixed-bed reactor had a diameter of 16 mm x 3 mm and a constant temperature zone of 8 cm. The catalyst dosage was 2 g, and the catalyst was packed with quartz beads above and below. The reaction temperature was 450°C at atmospheric pressure, with a reaction gas flow rate of 60 mL / min and an N:H ratio of 1:3.17. Calculations indicate that under these conditions, the mixed salt formed droplets ranging from 0.01 to 20 μm. The catalytic reaction yielded a synthetic ammonia yield of 0.99%.

[0113] Comparative Example

[0114] The current industrial ammonia synthesis Haber-Bosch process (molten iron catalyst) is implemented under high temperature and high pressure conditions (450-550°C, pressure 10-30 MPa), consuming 1%-2% of the world's total energy supply; at the same time, it emits approximately 500 million tons of carbon dioxide each year, accounting for about 1.8% of global carbon dioxide emissions. Fused iron catalysts are still the mainstream catalysts in industrial production.

[0115] The search for efficient ammonia synthesis catalysts other than molten iron catalysts is a relentless pursuit in the chemical industry. Since low temperatures favor higher conversion rates, better catalysts must operate at lower temperatures. The melting points of the liquid-phase ammonia-related molten salt catalysts of Example 3, consisting of mixed molten salts of 15MnCl₂-30LiCl-55KCl and 18MnCl₂-44KCl-38LiCl, are both below 350°C. Compared to the comparative examples, the catalysts of this example demonstrate superior catalytic performance. Furthermore, with the same formulation, the liquid drop catalysts exhibit higher efficiency than conventional melt catalysts.

[0116] The description of the present invention has been presented for purposes of illustration and description and is not intended to be exhaustive or to limit the invention to the form disclosed. Many modifications and variations will be apparent to those skilled in the art. The embodiments were chosen and described in order to better illustrate the principles of the invention and its practical application and to enable those skilled in the art to understand the invention and design various embodiments with various modifications as are suited for specific applications.

Claims

1. A liquid-phase ammonia-related molten salt catalyst, characterized in that: The liquid-phase ammonia-related molten salt catalyst is a liquid formed by heating and melting at least one material component of a metal halide, a metal hydroxide or a metal oxyacid, and is used for directly performing an interfacial contact catalytic reaction with a gaseous reactant under reaction conditions.

2. The liquid-phase ammonia-related molten salt catalyst according to claim 1, characterized in that: The metal in the metal halide, metal hydroxide and metal oxyacid is one of transition metal, alkali metal and alkaline earth metal.

3. The liquid-phase ammonia-related molten salt catalyst according to claim 1, characterized in that: The liquid-phase ammonia-related molten salt catalyst is in a liquid state formed by heating and melting at least one material component of a metal halide.

4. The liquid-phase ammonia-related molten salt catalyst according to claim 1, characterized in that: The liquid-phase ammonia-related molten salt catalyst uses at least three material components, each of which is selected from metal halides. In each metal halide, the metal is one of the transition metals manganese, iron, and ruthenium, and the halide is one of chloride and bromide.

5. An application of the liquid-phase ammonia-related molten salt catalyst according to any one of claims 1 to 4, characterized in that: It is applied to any reaction of ammonia decomposition, ammonia synthesis and SCR denitrification; wherein, when applied, under the reaction conditions, the gaseous reactants and the liquid-phase ammonia-related molten salt catalyst come into interfacial contact to cause a catalytic reaction, and part of the products and unreacted products are separated from the catalyst.

6. The use according to claim 5, characterized in that During application, the liquid phase ammonia molten salt catalyst formed by heating and melting is pre-introduced into the reaction vessel, and the reaction raw materials are introduced into the reaction vessel from the bottom of the reaction vessel. The reactants float up in the form of bubbles. Under the reaction conditions, the gaseous reactants and the liquid phase ammonia molten salt catalyst come into interfacial contact to cause a catalytic reaction.

7. The use according to claim 5, characterized in that When used, the liquid-phase ammonia-related molten salt catalyst reacts with gaseous reactants in the form of liquid droplets.

8. The use according to claim 7, characterized in that The average diameter of the droplets is less than 0.1 mm, and is achieved by any one of methods 1, 2, 3, and 4; wherein, Method 1 is to use an atomizing device to atomize the liquid phase ammonia molten salt catalyst formed by heating and melting into droplets, so that the gaseous reactants react with the droplets; Method 2 is to evaporate and condense the liquid ammonia molten salt catalyst placed in the reaction vessel to form droplets by heating, evaporation and recondensation, so that the gaseous reactants introduced into the area where the droplets are located react with the droplets; Method three is to pre-load the material components of the liquid-phase ammonia-related molten salt catalyst on the surface of a solid support and spray it into the reactor or pre-fill it into a fixed bed reactor. Under reaction conditions, the material components loaded on the surface of the solid support are heated and melted into droplets, so that the gas reactant flows through the support and fully contacts and reacts with the droplets on the support; Method 4: First, the material components of the liquid-phase ammonia-related molten salt catalyst are prepared into ultrafine powders, and the ultrafine powders are heated into liquid droplets under reaction conditions, and reacted with gaseous reactants.

9. The use according to claim 7, characterized in that When used, the method further includes: collecting the falling liquid droplets, removing impurities, and recycling the catalyst obtained after the impurities removal.

10. Use of the liquid-phase ammonia-related molten salt catalyst according to any one of claims 5 to 9, characterized in that: When applied to the reaction of ammonia decomposition, the reaction temperature is 500-1500°C; the reaction raw material is NH3, and the products are H2 and N2; and the products H2 and N2 and unreacted NH3 float to the liquid surface and are separated from the liquid phase ammonia molten salt catalyst.

11. Use of the liquid-phase ammonia-related molten salt catalyst according to any one of claims 5 to 9, characterized in that: When applied to the reaction of synthesizing ammonia, the reaction temperature is 400-1000°C, the reaction pressure is 0.1-50MPa; the reaction raw materials are a mixture of H2 and N2, and the product is NH3; and the product NH3 and unreacted H2 and N2 float to the liquid surface and are separated from the liquid phase ammonia-related molten salt catalyst.

12. The use of the liquid-phase ammonia-related molten salt catalyst according to claim 6, characterized in that: When applied to the SCR denitrification reaction, the reaction temperature is 280-1200°C; the reaction raw materials are NH3 and NO-containing reaction gas; the gaseous products and unreacted products after the reaction float to the liquid surface and are discharged after treatment.

13. Use of the liquid-phase ammonia-related molten salt catalyst according to any one of claims 7 to 9, characterized in that: When applied to the SCR denitrification reaction, the reaction temperature is 280-1200°C; NH3 and liquid ammonia molten salt catalyst droplets are sprayed together into the flue gas containing NO reaction raw gas in the reaction container; gaseous products and unreacted products float to the liquid surface and are discharged after treatment.

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