599 results about "Selective reduction" patented technology

An exhaust emission control device has a particulate filter 5 and a selective reduction catalyst 6 arranged side by side. An S-shaped communication passage 9 is arranged for introduction of exhaust gas 3 from a rear end of the filter 5 to a front end of the adjacent catalyst 6 in a forward fold-back manner and with a urea water addition injector 11 arranged midway of the passage 9. In order to satisfactorily disperse the urea water with enhanced mixing with the exhaust gas 3 even if the flow rate is increased, slits 12 are formed in circumferentially spaced positions on a rear end of a mixing pipe 9B constituting an upstream portion of the communication passage 9 so as to introduce the exhaust gas 3. A downstream end 9a of a gas gathering chamber 9A is connected to the rear end of the mixing pipe 9B such that the slits 12 are encased and the rear end of the mixing pipe 9B is closed.

The invention relates to a catalyst combination process of a sulfur recovering device, belonging to the technical field of sulfur recovery, and comprising a combustion furnace, a primary clotz reactorand a secondary clotz reactor connected in series with each other. The catalyst combination process is characterized in that: behind the secondary clotz reactor, a selective hydrogenation reduction reactor, a selective oxidation reactor and two absorption desulfurizing towers connected in parallel are connected in series; a deoxygenation protection-type sulfur recovery catalyst is filled in the upper part of the primary clotz reactor, and a TiO2 sulfur recovery catalyst is filled in the lower part; an auxiliary agent type sulfur recovery catalyst is filled in the secondary clotz reactor; a SO2 selective reduction catalyst is filled in the selective hydrogenation reduction reactor and selectively reduces the SO2 into elemental sulfur; H2S selective oxidation catalyst is filled in the selective oxidation reactor and selectively oxidizes the H2S into elemental sulfur. In the invention, the recovery rate of sulfur is high, and the tail gas after desulfuration can completely reach the national discharge requirement of GB16297-1996.

An exhaust gas purifying apparatus and method for an internal combustion engine, and an engine control unit are provided for appropriately determining the amount of reducing agent supplied to a NOx selective reduction catalyst to ensure good exhaust gas characteristics. The exhaust gas purifying apparatus comprises an ECU; a NOx selective reduction catalyst for purifying NOx in exhaust gases in an exhaust pipe; a NOx sensor disposed in the exhaust pipe at a location downstream of the NOx selective reduction catalyst for detecting a NOx concentration in exhaust gases; and an injector for supplying the NOx selective reduction catalyst with ammonia produced in an ammonia production unit. The ECU determines the amount of ammonia injected to the NOx selective reduction catalyst by the injector such that an estimate of the NOx concentration detected by the NOx sensor reaches a minimum value.

A structured catalyst for selective reduction of nitrogen oxides with ammonia using an ammonia-supplying compound. The catalyst is preferably used for exhaust gas treatment of diesel vehicles powered by diesel motors. The catalyst is characterized by the fact that it contains a reduction catalyst for selective reduction of nitrogen oxides with ammonia and a hydrolysis catalyst for the hydrolysis of urea, where the hydrolysis catalyst is applied in the form of a coating onto the reduction catalyst. By this arrangement of the two catalytic functions in one catalyst the exhaust gas system can be made very compactly and space saving. Moreover, advantageous synergistic effects result from the direct contact of the hydrolysis catalyst and the reduction catalyst.

A method and apparatus for reducing the percentage of nitrogen dioxide and nitrogen monoxide in an exhaust gas stream of an internal combustion engine, comprising the steps of injecting a hydrocarbon compound and optionally hydrogen into the exhaust gas stream; passing the exhaust gas through a first catalyst for selective reduction of a portion of the nitrogen oxides to nitrogen, ammonia, and N-containing species; passing the exhaust gas through a second catalyst for selective reduction of a portion of the nitrogen oxides with ammonia to molecular nitrogen; sensing ammonia concentration in the exhaust gas stream after passage through either or both of the first and second catalysts; and controlling by a controller in a feedback loop the injecting to an amount of hydrocarbon that will produce a predetermined concentration of ammonia and nitrogen oxides at the sensor that will lead to high NOx conversion.

An exhaust purification apparatus for an engine comprises a selective reduction-type NOx catalyst that is interposed in an exhaust passage of the engine and selectively reduces NOx contained in exhaust gas of the engine, an EGR device that recirculates exhaust gas of the engine to an intake side of the engine, an exhaust-purification-efficiency estimation unit that estimates exhaust purification efficiency of the NOx catalyst with respect to NOx, a target-exhaust-purification-efficiency calculation unit that calculates target exhaust purification efficiency with respect to NOx on the basis of an operational state of the engine, and a control unit that controls the EGR device to compensate a decrease amount of the estimated exhaust purification efficiency to the target exhaust purification efficiency.

An exhaust emission control device for an internal combustion engine, capable of supplying a just enough amount of reducing agent to a selective reduction catalyst even when a NOx purification ratio of the catalyst is changed by various causes, thereby enabling a high NOx purification ratio and very low exhaust emissions to be maintained. An ECU calculates a filtered value based on a signal from an exhaust gas concentration sensor, calculates a moving average value of a product of the filtered value and a reference input, calculates a control input such that the moving average value becomes equal to 0, and adds a reference input to the control input to calculate an FB injection amount. The ECU calculates an FF injection amount with a predetermined feedforward control algorithm, and adds the FF injection amount to the FB injection amount, to thereby calculate a urea injection amount.

An internal combustion engine exhaust gas purification apparatus purifies exhaust gas using a NOx storage-reduction catalyst unit and a NOx selective reduction catalyst unit. The NOx selective reduction catalyst unit is provided downstream of the NOx storage-reduction catalyst unit in an exhaust gas passage. An urea injecting mechanism, for example an injection valve, injects urea into the exhaust gas passage. An urea injection controller prohibits urea injection from the urea injecting mechanism if at least one of the temperatures of the NOx storage-reduction catalyst unit and the NOx selective reduction catalyst unit is equal to or lower than a reference temperature. As such, production of cyanic acid is minimized, and therefore leaks of cyanic acid from the NOx storage-reduction catalyst unit and / or the NOx selective reduction catalyst unit can be suppressed.

The present invention provides a monatomic metal-doped few-layer molybdenum disulfide electrocatalytic material, a preparing method thereof, and a method for electrocatalytic nitrogen fixation. The material has a few-layer ultra-thin and irregular flake-like microstructure with a length and a width of nanometer scale. A doping metal in the monatomic metal-doped few-layer molybdenum disulfide electrocatalytic material is dispersed in a form of single atoms. When the catalyst is used in electrochemical reduction of N2, a Faradic efficiency in selective reduction of N2 into NH4+ is 18% or above, and stability of the catalyst is better.

In an exhaust purification system having a urea addition device adding a urea aqueous solution to an NOx catalyst of selective reduction type provided in an exhaust passage in an internal combustion engine, a sensor detecting an ammonia concentration is provided at the downstream side of the NOx catalyst. During fuel cut, a predetermined amount of urea aqueous solution is added. Then, based on a sensor output obtained at this time, an abnormality in at least one of the urea addition device and the urea aqueous solution is detected. The addition of the urea aqueous solution during the fuel cut prevents reactive consumption between urea and NOx. The sensor output corresponding to the amount of the urea aqueous solution is obtained. This output condition is compared with a normal one to allow determination of whether or not an appropriate amount of urea aqueous solution of appropriate quality has been added.

An exhaust gas purification method which is capable of purifying nitrogen oxide to be included in exhaust gas from a lean burn engine such as a boiler, a gas turbine or a lean-burn-type gasoline engine, a diesel engine, effectively, in particular, even at low temperature, with spray-supplying an aqueous solution of urea as the reducing component to the selective reduction catalyst.The exhaust gas purification method for reducing selectively NOx in exhaust gas, which is exhausted from a lean burn engine, with a selective reduction catalyst and ammonia, characterized in thatan aqueous solution of urea is spray-supplied to the selective reduction catalyst, comprising at least the following zeolite (A) and the hydrolysis promotion component of urea (B), and it is contacted at 150 to 600° C., and ammonia is generated in a ratio of [NH3 / NOx=0.5 to 1.5] to NOx in exhaust gas, as converted to ammonia, and a nitrogen oxide is decomposed into nitrogen and water.zeolite (A): zeolite comprising an iron elementhydrolysis promotion component (B): a complex oxide comprising at least one kind selected from titania or titanium, zirconium, tungsten, silicon or alumina

The invention relates to a catalyst of selective reduction of nitrogen oxide by ammonia, which mainly solves the existing problems that the commonly used NH3-SCR catalyst system is toxic to environment and human body, the anti-SO2 poisoning ability of the catalyst system is poor in the reference and the catalyst system can not adapt to the conditions of high space velocity. The invention adopts cheap and non-toxic raw materials to prepare a Fe-Ti oxide catalyst with high activity, selectivity, stability and anti-S2 poisoning ability by the simple and practicable co-precipitation method, which can better solve the existing technical problems. If the catalyst is loaded on honeycomb ceramics after being made into pulp, the catalyst is hopeful to be put into practical application of flue gas denitrification of coal-fired power plants.

The invention provides a comprehensive recovery method for a waste lithium ion battery. The method comprises the following steps: three-element waste lithium battery cell powder is leached by sulfuricacid and potassium permanganate for the first time so as to obtain a first leaching solution and a first leaching residue; sodium carbonate is used for carrying out lithium precipitation on the firstleaching solution to obtain lithium carbonate; selective reduction leaching is carried out on the first leaching residue by using hydrogen peroxide and sulfuric acid so as to obtain a second leachingsolution and a second leaching residue; the pH value of the second leaching solution is adjusted to be 4.2-4.5, and P204 is used for extracting the second leaching solution so as to obtain a P204 raffinate and a P204 loaded organic phase; reverse extraction is carried out on the P204 loaded organic phase by using sulfuric acid, and evaporating and crystallizing are carried out to prepare manganese sulfate; the pH value of the P204 raffinate is adjusted to be 4.5-5, and the P204 raffinate is extracted by using C272 so as to obtain a C272 extracting solution and a C272 loaded organic phase; reverse extraction is carried out on a C727 loaded organic phase by sulfuric acid to obtain a cobalt sulfate solution, and evaporating and crystallizing are carried out to prepare battery-grade cobalt sulfate; and the pH value of a C272 raffinate is adjusted to be 5-5.5, the C272 extracting solution is extracted by using P507 to obtain a P507 loaded organic phase, sulfuric acid back-extraction is carried out on the P507 loaded organic phase to obtain a nickel sulfate solution, and evaporating and crystallizing are carried out to obtain nickel sulfate.