51 results about "Ternary catalyst" patented technology

An internal combustion engine includes a three-way catalyst provided in an exhaust path, an upstream-side air-fuel ratio sensor provided on the exhaust upstream side of the three-way catalyst, and a downstream-side air-fuel ratio sensor provided on the exhaust downstream side of the three-way catalyst. The CPU executes a correction process of making a correction of addressing an output deviation of the upstream-side air-fuel ratio sensor based on an output of the upstream-side air-fuel ratio sensor and an output of the downstream-side air-fuel ratio sensor in a case where the output of the downstream-side air-fuel ratio sensor indicates a value near the stoichiometric air-fuel ratio during the execution of air-fuel ratio control of controlling the air-fuel ratio of an air-fuel mixture based on the output of the upstream-side air-fuel ratio sensor such that the air-fuel ratio of the air-fuel mixture is an air-fuel ratio near the stoichiometric air-fuel ratio.

This invention relates to the field of three-way catalyst processing technology and discloses a three-way catalyst raw material processing device, including a support unit. The support unit includes a stirring shell and a sealing cover, with the end faces of the stirring shell and the sealing cover fitting together. A drive unit, a preliminary stirring unit, and a mixing stirring unit are installed inside the stirring shell and the sealing cover. In this invention, the mixing stirring unit, during the rotation of the drive shaft, drives the bottom drive bevel gear to rotate. The drive bevel gear's side wall meshes with a driven bevel gear, which in turn drives the connected ring and arc-shaped support to rotate synchronously. The rotation of the arc-shaped support causes the connecting shaft and the positioning rod to rotate alternately, thereby stirring the raw material passing through the preliminary stirring unit. This results in more thorough mixing. Furthermore, the raw material passing through the preliminary stirring unit is fed slowly, reducing the occurrence of uneven mixing caused by simultaneous feeding. This method is suitable for widespread application and promotion.

The invention relates to the technical field of natural gas engine control, and discloses an engine aftertreatment catalyst control method and device, electronic equipment and a medium. The method comprises the following steps: acquiring the oxygen storage capacity corresponding to at least one degradation degree three-way catalyst TWC; constructing a first mapping relation between each oxygen storage amount and the opening degree value of the throttle valve under the specific working condition of the engine; constructing a second mapping relation between each oxygen storage amount and the voltage set value of the rear oxygen sensor under the specific working condition of the engine; in the actual operation process of the engine, the degradation degree of the TWC is monitored in real time, and the current oxygen storage amount of the TWC is determined based on the degradation degree; and the emission state of the engine is adjusted based on the current oxygen storage amount, the first mapping relation and the second mapping relation so that the emission state can meet the emission standard. The exhaust emission level of the automobile can be improved, and energy consumption is reduced.

The invention relates to a three-way catalyst as well as a preparation method and application thereof. The three-way catalyst comprises a carrier and an active coating coated on the surface of the carrier, the active coating comprises a bottom layer, a middle layer and an upper layer from inside to outside; the bottom layer comprises an oxygen storage material layer, and the oxygen storage material layer comprises activated aluminum oxide and a rare earth oxygen storage material; the middle layer comprises a Pd coating, and the upper layer comprises a Pt-Rh-Ru coating. The three-way catalyst provided by the invention adopts a three-layer coating structure, so that the poisoning effect of sulfur in gas on noble metal palladium is effectively reduced, and the performance and durability of the catalyst are greatly improved. Activated aluminum oxide and a rare earth oxygen storage material are selected as bottom layer materials of the catalyst, the oxygen storage performance of the catalyst is greatly improved, and the catalyst has obvious performance advantages when coping with engine loads with large air-fuel ratio fluctuation.

Provided is a catalyst temperature calculation device capable of calculating the temperature of a three-way catalyst having an oxygen storage capability with high accuracy. This catalyst temperature calculation device is provided with: an estimation unit that estimates, on the basis of the amount of heat of exhaust gas discharged from an engine, the temperature of a three-way catalyst that has oxygen storage capacity and purifies the exhaust gas from the engine; and a correction unit that corrects the temperature of the three-way catalyst estimated by the estimation unit on the basis of the ammonia concentration in the exhaust gas discharged from the three-way catalyst into which the exhaust gas having a rich air-fuel ratio flows.

The invention relates to the technical field of motor vehicle tail gas after-treatment, and discloses a three-way catalyst conversion efficiency online detection method based on infrared spectroscopic analysis. The method comprises the following steps: continuously acquiring and fusing infrared spectrum and working condition data by establishing a data channel, constructing a spectral feature domain representing the intrinsic state of the catalyst, and mapping real-time data into a feature vector sequence; the state of the active site on the surface of the catalyst is estimated by analyzing sequence change, and then the real-time activity degree of each chemical reaction path is deduced. The pollutant conversion amount is distributed based on the path activeness weight, the contribution of each path is calculated, the instantaneous conversion efficiency is summarized and evaluated, and finally an activity attenuation track is drawn and a diagnosis instruction is triggered. According to the technology, transformation from macroscopic efficiency monitoring to microscopic reaction path analysis is realized, the root of efficiency reduction can be accurately positioned, and early warning is realized.

The invention relates to the technical field of tail gas purification, in particular to a front-section three-way catalyst, a three-way catalyst system and a preparation method of the three-way catalyst system. The front-section three-way catalyst comprises a front-section catalyst matrix and a front-section molecular sieve coating, and the front-section molecular sieve coating comprises a first molecular sieve coating, a second molecular sieve coating and a third molecular sieve coating which are stacked and used for adsorbing nitrogen oxides; the second molecular sieve coating comprises a second front molecular sieve coating for adsorbing hydrocarbon and a second rear molecular sieve coating for adsorbing carbon monoxide, and the third molecular sieve coating comprises a third front molecular sieve coating for adsorbing hydrocarbon and a third rear molecular sieve coating for adsorbing carbon monoxide; the front-section molecular sieve coating with a three-layer structure can be used for enriching nitrogen oxide, hydrocarbon and carbon monoxide in a partitioned manner, so that the reaction efficiency of the three-way catalyst can be improved.

The invention provides a graphite core column for high-temperature and high-pressure synthesis of high-thermal-conductivity diamond and a preparation method, the graphite core column is of a three-layer concentric cylinder structure, and the graphite core column is sequentially composed of a nitrogen removal core layer, a catalytic reaction layer and a sealing pipe layer from inside to outside. The nitrogen removal core layer forms an active defense system, Ti / Zr elements located in the core react with nitrogen to produce stable nitrides, nitrogen impurities are firmly captured and fixed to the nitrogen removal core layer, and the diamond growth environment of the catalytic reaction layer is purified; and the catalytic reaction layer is formed by mixing a Ni-Mn-Cu ternary catalyst and graphite. The catalyst system ensures that the dynamic processes of dissolution and precipitation of the carbon source in the catalyst are consistent, and stable growth of diamond single crystals is facilitated; the outer-layer sealing pipe graphite is used for sealing an internal reaction system and preventing external pollution. The three layers of structures perform their own functions and cooperate with one another, impurity removal, growth and pressure maintaining are integrally designed, and the system solves the three core problems of nitrogen pollution, uneven growth and pressure fluctuation in synthesis of the high-thermal-conductivity diamond.

Methods for thermal control, including: Determine whether a catalytic converter (18) is active; Determine whether a catalyst (20) is active for selective catalytic reduction (SCR); Adjusting the air-fuel ratio of a machine (14) for operation at a stoichiometric ratio and retarding the ignition spark of the machine (14) when the catalytic converter (18) is not active; and Perform fuel injection when the catalytic converter (18) is active and the SCR catalyst (20) is not active; characterized by the fact that the catalytic converter (18) is a three-way catalyst (18); wherein, based on a first temperature of the catalytic converter (18) and a first active volume of the catalytic converter (18), it is determined whether the catalytic converter (18) is active; wherein, based on a second temperature of the SCR catalyst (20) and a second active volume of the SCR catalyst (20), it is determined whether the SCR catalyst (20) is active, wherein the second temperature is an average temperature determined as a weighted mean of temperatures T1 and T2 measured upstream and downstream of the SCR catalyst (20) according to the equation WA = x * T1 + (x-1) * T2, where WA is the weighted mean and x is a calibrated value between 0 and 1; and wherein the fuel injection is carried out by a post-fuel injection and / or by direct injection of fuel into an exhaust system (16) of the machine (14).

The invention discloses a parameter correction system and method for low emission. The system comprises a gas machine aftertreatment device and an electric control unit. The gas machine post-treatment device comprises a first three-way catalyst converter, a second three-way catalyst converter and a particle trap; a temperature sensor is arranged between the first three-way catalyst converter and the second three-way catalyst converter, and a nitrogen oxide sensor is arranged between the second three-way catalyst converter and the particle trap; the temperature sensor and the nitrogen oxide sensor are electrically connected with the electric control unit respectively; the gas machine post-processing device is used for acquiring a first temperature and an actual oxygen concentration through a temperature sensor and a nitrogen oxide sensor and sending the first temperature and the actual oxygen concentration to the electric control unit; and the electronic control unit is used for correcting the original engine parameters of the engine and the sensor value of the nitrogen oxide sensor based on the first temperature and the actual oxygen concentration so as to optimize the performance and the fuel efficiency of the engine. According to the invention, the accuracy of emission control and the reliability of the system can be improved.

A natural gas combustion system and its burner assembly for simulating the working environment of a three-way catalytic converter include an intake assembly, a combustion assembly, a cooling assembly, and a reaction assembly. The intake assembly includes a gas bus and an air bus. The combustion assembly includes a primary combustion mechanism and several secondary combustion mechanisms. It also includes a combustion process, comprising a primary combustion stage and a secondary combustion stage. Furthermore, it includes a regulating component. When the regulating component is located on the gas branch line, it sequentially includes a pneumatic valve, a filter, a flow meter, a check valve, and a flame arrester. When the regulating component is located on the air branch line, it sequentially includes a filter, a flow meter, and a check valve. This invention employs a multi-stage burner to perform multi-stage combustion of natural gas to simulate the reaction environment during normal operation of a three-way catalytic converter. It also features a complete automated closed-loop system for dynamic adjustment, significantly improving experimental accuracy through the air-fuel ratio meter and air-fuel ratio control unit of each burner stage.

The application discloses a catalyst for catalyzing polyethylene degradation to prepare ethylene and a preparation method thereof. x In y WO3 / CeO2 catalyst. The application highly disperses active metals in the carrier through simple impregnation, calcination and reduction steps, and the catalyst has the ability of dehydrogenation of noble metals and breaking of carbon-carbon bonds of WO3, realizes efficient conversion of polyethylene into ethylene at a lower temperature, and has a wide application prospect compared with other polyethylene ethylene systems.

The invention discloses a three-way catalyst as well as a preparation method and application thereof. The three-way catalyst comprises a carbon carrier, and a noble metal, a transition metal and a rare earth metal which are loaded on the carbon carrier, the noble metal is selected from Pt and Pd, the transition metal is selected from Fe, Co or Ni, and the rare earth metal is selected from Ce or La. The invention provides application of the three-way catalyst in magnetic field driven room-temperature CO oxidation reaction. The three-way catalyst has the high activity of precious metal, the oxygen storage capacity of rare earth metal and the magnetic response characteristic of transition metal, and under the action of a direct-current magnetic field generated by adding a magnet, the CO oxidation reaction conversion rate can be increased by 10-30 times in a room temperature state.

The application discloses a preparation method and application of an aluminum-copper-based ternary catalyst for carbon dioxide hydrogenation to methanol, and the method is as follows: pseudo-boehmite is dispersed in a solvent, hydrochloric acid is added, copper nitrate and an auxiliary metal precursor are added into the mixture, and then the aluminum-copper-based ternary catalyst is obtained after stirring, aging, drying and calcination. The aluminum-copper-based ternary catalyst preparation method is simple, the carbon dioxide conversion rate is close to the equilibrium conversion rate under high space velocity, the selectivity of methanol is close to 100%, and the catalyst has an industrial application prospect.

The invention discloses a gasoline engine tail gas purification three-way catalyst and a preparation method thereof.The gasoline engine tail gas purification three-way catalyst comprises a carrier and a coating, the carrier is coated with the coating, the coating comprises aluminum oxide, precious metal and a cerium-zirconium composite oxygen storage material, and the cerium-zirconium composite oxygen storage material is prepared from, by mass, 5-10% of aluminum oxide, 5-10% of precious metal and 5-10% of cerium-zirconium composite oxygen storage material. Comprising 40%-70% of zirconium oxide, 20%-50% of cerium oxide, 2%-3% of lanthanum oxide, 2%-3% of yttrium oxide, 1%-2% of phosphorus oxide, 1%-2% of tin oxide and 2%-3% of antimony oxide. Therefore, by using the gasoline engine tail gas purification three-way catalyst, the cost can be reduced, and the catalytic performance of the gasoline engine tail gas purification three-way catalyst is equivalent to that of a Pr / Nd adding scheme.

The present application belongs to the technical field of separating and purifying platinum, palladium and rhodium in a three-way catalyst, and particularly relates to a method for separating and purifying platinum, palladium and rhodium in a three-way catalyst by molten salt electrolysis, comprising the following steps: S1 electrolyte system construction: taking the three-way catalyst metal to be purified as an anode, adopting a titanium plate as a cathode, adopting a closed inert protection environment electrolytic cell, and adopting a eutectic molten salt as an electrolyte; S2 step-by-step electrolytic deposition: the first step is platinum deposition; the second step is palladium deposition; and the third step is rhodium separation; and S3 product treatment: the treatment of platinum and palladium products comprises respectively taking out the cathodes in the platinum and palladium deposition stages, stripping the deposits, and then vacuum smelting to obtain platinum and palladium products; the treatment of rhodium products comprises taking out the anode, collecting the anode mud on the surface of the anode, treating to obtain rhodium fine products, and then vacuum smelting the rhodium fine products to obtain rhodium products; the present application can efficiently separate platinum, palladium and rhodium, the products have high purity, and the present application is environmentally friendly.

To provide a catalyst temperature calculation device capable of accurately calculating the temperature of a three way catalyst having oxygen storage capacity.SOLUTION: A catalyst temperature calculation device comprising: an estimation unit configured to estimate a temperature of a three way catalyst that has an oxygen storage capacity and purifies exhaust gas from an engine, based on a heat quantity of the exhaust gas discharged from the engine; and a correction unit configured to correct the temperature of the three way catalyst estimated by the estimation unit, based on an ammonia concentration in exhaust gas discharged from the three way catalyst into which exhaust gas having a rich air-fuel ratio flows.SELECTED DRAWING: Figure 2

An internal combustion engine (1) has a three-way catalyst (15). An engine controller (9) has an oxygen amount calculation unit (102) determining an amount of oxygen flowing into the three-way catalyst (15) per unit time and an oxygen storage amount calculation unit (108) estimating a current oxygen storage amount by integrating positive and negative oxygen amount. A reference oxygen storage capacity calculation unit (107) outputs a reference oxygen storage capacity according to an intake air amount output by an intake air amount calculation unit (101) so that as the intake air amount is larger, the reference oxygen storage capacity becomes smaller. A catalyst diagnosis unit (104) judges catalyst deterioration by comparing a current oxygen storage capacity with the reference oxygen storage capacity set by taking the intake air amount into consideration.

This invention discloses a synergistic method for removing NO x This paper describes a three-way catalyst for toluene, its preparation method, and its application, belonging to the field of industrial waste gas treatment technology. The catalyst is prepared by hydrothermal synthesis of Ce, Ti, and Mn-based metal-organic frameworks (MOFs), which are then used as sacrificial templates and calcined in air to obtain Ce1Ti. x A Mn₂O / MOFs ternary catalyst, wherein 1 ≤ x ≤ 5. This invention also discloses a method for preparing this catalyst, including steps such as solution preparation, stirring, hydrothermal reaction, vacuum drying, and high-temperature calcination. This catalyst can achieve NO reduction at 240-300℃. x It can be used in synergistic removal with toluene, with removal efficiencies of over 80%. It has the advantages of simple preparation process, low raw material cost, high catalytic activity, good stability and no secondary pollution. It is suitable for the simultaneous purification of nitrogen oxides and volatile organic compounds in industrial stationary source flue gas.

The invention relates to a control device for an internal combustion engine. An internal combustion engine includes a three-way catalyst provided in an exhaust passage, an upstream side air-fuel ratio sensor provided on an exhaust upstream side of the three-way catalyst, and a downstream side air-fuel ratio sensor provided on an exhaust downstream side of the three-way catalyst. During execution of air-fuel ratio control in which an air-fuel ratio of an air-fuel mixture is controlled on the basis of an output of an upstream-side air-fuel ratio sensor so that the air-fuel ratio of the air-fuel mixture is an air-fuel ratio in the vicinity of a theoretical air-fuel ratio. When the output of the downstream side air-fuel ratio sensor indicates a value near the stoichiometric air-fuel ratio, the CPU executes a correction process of making a correction to solve the output deviation of the upstream side air-fuel ratio sensor based on the output of the upstream side air-fuel ratio sensor and the output of the downstream side air-fuel ratio sensor.

The application discloses a kind of ternary catalysts for carbon dioxide hydrogenation to methanol prepared by mechanical ball milling method and application thereof, the method is as follows: Cu (OH) 2 and Zn (OH) 2 and auxiliary metal precursor are weighed and added into ball mill jar, grinding ball is added, finally the ball mill jar is placed in ball mill to set condition and carries out ball milling, after ball milling, drying, calcination and reduction are carried out to obtain CuZn-based ternary catalyst;The catalyst preparation method of the application is simple, each component can be uniformly dispersed, and a large number of oxygen vacancies can be formed after adding the auxiliary agent, which improves the catalyst activity and is more suitable for industrialization.

The application relates to an outlet cooling device of a three-way catalyst drying furnace, and relates to the field of three-way catalyst processing devices, which comprises a supporting grid for placing three-way catalysts and a cooling box, the supporting grid is located on the cooling box, a fan is arranged in the cooling box, a wind guide cavity and a wind distribution cavity are arranged between the air outlet of the fan and the supporting grid, a wind guide plate is arranged on the side wall of the wind guide cavity, a first wind swinging unit for up-down wind swinging and a second wind swinging unit for left-right wind swinging are arranged in the wind distribution cavity, a driving assembly for driving the first wind swinging unit to swing is arranged on the cooling box, and the first wind swinging unit drives the second wind swinging unit to swing through a connecting assembly. The application has the effects of improving the uniformity of three-way catalyst cooling and effectively avoiding cracks of the three-way catalyst.

This application discloses a parameter correction system and method for low emissions. The system includes: a gas engine aftertreatment device and an electronic control unit (ECU). The gas engine aftertreatment device includes a first three-way catalytic converter, a second three-way catalytic converter, and a particulate filter. A temperature sensor is disposed between the first and second three-way catalytic converters, and a nitrogen oxide (NOx) sensor is disposed between the second three-way catalytic converter and the particulate filter. The temperature sensor and the NOx sensor are electrically connected to the ECU. The gas engine aftertreatment device is used to acquire a first temperature and an actual oxygen concentration through the temperature sensor and the NOx sensor, and send them to the ECU. The ECU is used to correct the original engine parameters and the NOx sensor values ​​based on the first temperature and the actual oxygen concentration to optimize engine performance and fuel efficiency. Using this application can improve the accuracy of emission control and the reliability of the system.

The invention relates to the technical field of degradation of hydrodynamic cavitation catalysis, in particular to a degradation device based on hydrodynamic cavitation catalysis and an antibiotic wastewater degradation method thereof, and the degradation device comprises the following steps: S1, adding antibiotic-containing wastewater into a liquid storage tank, and adding a preset amount of catalyst to enable the catalyst and the wastewater to form a uniform solid-liquid mixture, meanwhile, stirring and temperature control preparation is carried out on the liquid storage tank; s2, a water pump is started, so that the solid-liquid mixture enters a Venturi cavitation generator through a main circulation pipeline, a hydrodynamic cavitation effect is formed in a contraction section, a throat part and a diffusion section of the Venturi cavitation generator, and circulating flow is completed; the synthesized ternary ZIS / NFO / BC catalyst has the advantages of being high in stability, resistant to chemical corrosion, resistant to light corrosion and the like, and compared with a single hydrodynamic cavitation process or a single photocatalysis process, the hydrodynamic cavitation catalysis synergistic degradation process greatly improves the degradation efficiency of antibiotic doxycycline hydrochloride.

The invention relates to a three-way catalyst defect detection method and system based on a visual language model, and relates to the field of three-way catalyst defect detection. According to the technical scheme, the problems that existing detection is low in efficiency, high in subjectivity, poor in complex defect adaptation and lack of continuous learning ability are solved in a targeted mode, efficient defect screening and deep intelligent analysis are achieved, the first-stage target detection model ensures the high-throughput detection requirement of a production line at a high frame rate, and the target detection model adapts to the large-batch production takt; in the second stage, the visual language model realizes defect analysis depth and scene flexibility which are difficult to reach by a traditional method by means of semantic understanding ability, and the overall detection efficiency is maximized through cooperation of the two. Besides, when a new defect mode appears, the second-stage visual language model can accurately analyze and generate structured description, the structured description is directly used for incremental training of the first-stage target detection model after format conversion, and a self-adaptive and self-perfect virtuous circle is formed along with data accumulation and continuous evolution of system detection capability.

The invention relates to a SiO2-coated Al2O3 loaded rare earth three-way catalyst, a preparation method thereof and application of the catalyst in polycarbonate synthesis, and belongs to the technical field of polymer synthesis. According to the catalyst, SiO2-coated Al2O3 serves as a carrier to load a rare earth three-way catalyst, SiO2-coated Al2O3 is of a double-layer structure, the inner layer of SiO2-coated Al2O3 is SiO2, the outer layer of SiO2-coated Al2O3 is Al2O3, and the rare earth three-way catalyst contains yttrium trichloroacetate, glycerin and diethyl zinc. The SiO2-coated Al2O3 carrier with a double-layer structure is prepared, and the rare earth three-way catalyst is loaded by utilizing the characteristics of large specific surface area, abundant radial pore structures and abundant contactable active surfaces of the SiO2-coated Al2O3 carrier, so that the efficient polycarbonate synthesis catalyst is obtained; the catalyst has the characteristics of high catalytic efficiency (TON), high polycarbonate molecular weight, high carbonate chain link content, easiness in separation after the reaction is finished, and the like.

The present application relates to the field of motor vehicle exhaust aftertreatment technology, and discloses a three-way catalyst conversion efficiency online detection method based on infrared spectrum analysis. The method comprises continuously acquiring and fusing infrared spectrum and working condition data by establishing a data channel, constructing a spectrum characteristic domain representing the intrinsic state of the catalyst, and mapping real-time data into a sequence of feature vectors. By analyzing the sequence changes, the state of the active sites on the catalyst surface is estimated, and then the real-time activity of each chemical reaction path is deduced. Based on the path activity, the pollutant conversion amount is allocated, the contribution of each path is calculated, and the instantaneous conversion efficiency is evaluated by summarizing. Finally, the activity decay trajectory is drawn and the diagnostic instruction is triggered. This technology realizes the transition from macroscopic efficiency monitoring to microscopic reaction path analysis, can accurately locate the root cause of efficiency decline and realize early warning.

The utility model relates to the technical field of catalyst recovery devices, in particular to a waste three-way catalyst recovery device which comprises a device body, a screening mechanism is fixedly connected to one side of the device body and rotationally connected to the interior of the device body, and the screening mechanism comprises a servo motor. The servo motor is fixedly installed on one side of the device body, and the conveying mechanisms are fixedly connected to the two sides of the device body and located below the screening mechanism. According to the waste catalyst magnetic separation device, waste catalysts can be crushed through mutual cooperation of internal parts of the screening mechanism, magnetic substances in the waste catalysts are subjected to magnetic separation operation, precious metal powder with different characteristics in the catalysts can be transported through mutual cooperation of internal parts of the transportation mechanism, and therefore the waste catalyst magnetic separation device is simple in structure and convenient to use. The precious metal powder is layered and separated in the flotation machine, so that the occupied area of a plurality of recovery treatment devices can be reduced.

The invention relates to a method for separating platinum, palladium and rhodium from bromine water in an iron alloy, which comprises the following steps: 1) pretreating raw materials to obtain a ferrosilicon alloy; 2) preparing a pregnant solution; sequentially crushing and calcining the ferrosilicon alloy, and adding bromine water into the calcined product for dissolving reaction to obtain a pregnant solution; and (3) separating precious metals, sequentially carrying out ammonia water regulation and hydrochloric acid reaction on the pregnant solution to obtain platinum-rhodium liquid and precipitates, adding a reducing agent into the precipitates to obtain metal palladium, sequentially adding an oxidizing agent and ammonium chloride into the platinum-rhodium liquid to react to obtain rhodium-containing liquid and ammonium chloroplatinate precipitates, adding formic acid into the ammonium chloroplatinate precipitates, and introducing hydrogen to obtain metal platinum, sodium hydroxide, hydrochloric acid, DETA and formic acid are sequentially added into the rhodium-containing liquid for a reaction, and metal rhodium is obtained. The method is ideal in design, not only improves the dissolution rate of platinum, palladium and rhodium, but also improves the separation efficiency, and can meet the requirements of industrial production scale for recovering and refining platinum, palladium and rhodium in the iron alloy in the waste three-way catalyst, and the precipitation rate of platinum, palladium and rhodium reaches 99% or above.

A subject matter of the invention is a catalyst comprising a support and an active phase consisting of nickel, molybdenum and tungsten, and phosphorus, the nickel content, measured in the NiO form, is between 3% and 4% by weight; the molybdenum content, measured in the MoO3 form, is between 2% and 4% by weight; the tungsten content, measured in the WO3 form, is between 34% and 40% by weight; the phosphorus content, measured in the P2O5 form, is between 3% and 4% by weight, with respect to the total weight of the catalyst; the WO3 / MoO3 molar ratio is between 5.3 and 12.4 mol / mol, the NiO / (WO3+MoO3) molar ratio is between 0.20 and 0.33 mol / mol and the P2O5 / (WO3+MoO3) molar ratio is between 0.21 and 0.34 mol / mol. The invention also relates to its method of preparation and to its use in hydrotreating and / or hydrocracking.