35 results about "Desorption kinetics" patented technology

A method is presented for estimating an amount of ammonia stored in a urea-based SCR catalyst based on a dynamic model of the catalyst. The model takes into account chemical and physical properties of the catalyst, such as catalyst volume, the number of available ammonia storage cites, adsorption and desorption dynamics, as well as sulfur poisoning, thermal aging, and different catalyst operating temperatures, and generates the estimate based on a measured or estimated amount of NOx in an exhaust gas mixture upstream of the catalyst, an amount of reductant injected into the catalyst to facilitate NOx reduction, and on a measured value of NOx in an exhaust gas mixture downstream of the catalyst. The estimated ammonia storage amount is then used to control the amount of reductant injected into the catalyst to maintain desired ammonia storage amount such that maximum NOx conversion efficiency coupled with minimum ammonia slip are achieved.

A heated DESI spray device provides improved resolution or control of analyte desorption at a target locus on a sample. Heating controls spot size and enhances resolution in an imaging mode without impairing signal level. Additionally or alternatively the heated DESI spray may control desorption kinetics of a target analyte or otherwise control analyte discrimination in detection mode. One embodiment of the DESI spray is heated by heating nebulizing gas that accompanies the electrosprayed solvent. Another embodiment heats a separate gas stream that transports or directs desorbed material to the ion aperture of an analysis instrument. Heating may reduce size of primary droplets, alter the impact dynamics or the energy delivered by the spray to the surface, reduce size of secondary droplets and/or assure desolvation, improve species selectivity or otherwise affect sampling and enhance the ion signal level.

A method is presented for estimating an amount of ammonia stored in a urea-based SCR catalyst based on a dynamic model of the catalyst. The model takes into account chemical and physical properties of the catalyst, such as catalyst volume, the number of available ammonia storage cites, adsorption and desorption dynamics, as well as poisoning, thermal aging, and different catalyst operating temperatures, and generates the estimate based on a measured or estimated amount of NOx in an exhaust gas mixture upstream of the catalyst, an amount of reductant injected into the catalyst to facilitate NOx reduction, and on a measured value of NOx in an exhaust gas mixture downstream of the catalyst. The estimated ammonia storage amount is then used to control the amount of reductant injected into the catalyst to maintain desired ammonia storage amount such that maximum NOx conversion efficiency coupled with minimum ammonia slip are achieved.

A method is presented for estimating an amount of ammonia stored in a urea-based SCR catalyst based on a dynamic model of the catalyst. The model takes into account chemical and physical properties of the catalyst, such as catalyst volume, the number of available ammonia storage cites, adsorption and desorption dynamics, as well as poisoning, thermal aging, and different catalyst operating temperatures, and generates the estimate based on a measured or estimated amount of NOx in an exhaust gas mixture upstream of the catalyst, an amount of reductant injected into the catalyst to facilitate NOx reduction, and on a measured value of NOx in an exhaust gas mixture downstream of the catalyst. The estimated ammonia storage amount is then used to control the amount of reductant injected into the catalyst to maintain desired ammonia storage amount such that maximum NOx conversion efficiency coupled with minimum ammonia slip are achieved.

A hydrogen storage material having improved hydrogen absorbtion and desorption kinetics is provided by adding graphite to a complex hydride such as a metal-doped alanate, i.e., NaAlH₄. The incorporation of graphite into the complex hydride significantly enhances the rate of hydrogen absorbtion and desorption and lowers the desorption temperature needed to release stored hydrogen.

The invention belongs to the technical field of hydrogen storage materials and particularly relates to a metal oxide and porous material composite hydrogen storage material and a preparation method thereof. The metal oxide and porous material composite hydrogen storage material is formed by compounding magnesium hydride, a porous material and a metal oxide, and the weight ratio of the magnesium hydride to the porous material to the metal oxide is (100-10): (5-0.1): (1-0.05). The magnesium hydride is taken as a base material, and metal oxide particles are mixed and grinded to obtain an activated magnesium hydride material; and the obtained activated magnesium hydride material is mixed with the porous material, and ball milling or compression is carried out to obtain the composite hydrogen storage material. According to the material and the preparation method, nanoscale metal oxide particles are added and compounded with the porous material, so that the hydrogenation speed of magnesium-based composite powder in the hydrogen charging ball milling process can be increased, and meanwhile, the hydrogen storage material has good characteristics in the aspects of hydrogen adsorption and desorption kinetics in combination with the properties such as excellent pore channels and high surface area of the porous material.

The invention provides an AB type hydrogen storage alloy used for storing tritium and a preparation method of the AB type hydrogen storage alloy, and relates to the technical field of hydrogen storage alloy. The general formula of components of the AB type hydrogen storage alloy used for storing the tritium is Zr1-xTixCo1-yFey, wherein the x is greater than or equal to 0.1 but smaller than or equal to 0.4, and the y is greater than or equal to 0.1 but smaller than or equal to 0.2. The hydrogen storage alloy provided by the invention has good hydrogen-induced disproportionation resistance, and excellent hydrogen absorption and desorption kinetics performance and indoor-temperature hydride balance pressure, and the preparation method of the hydrogen storage alloy is simple, easy to implement and high in preparation efficiency and practicability.

A method for providing in situ chemical transformation and ionization of a portion (e.g., inorganic oxidizer) of a sample via an analyte detection system is disclosed herein. The method includes introducing a gas into an ionization source of the analyte detection system via an inlet. The method further includes generating ions within the ionization source and directing the gas and generated ions through and out of the ionization source and to the sample. The sample is located proximal to the ionization source in an ambient environment. The ions chemically react with the sample and desorb and ionize an analyte from the sample, the analyte being generated from the inorganic oxidizer, the desorbed analyte having a lower melting point and/or better desorption kinetics than the inorganic oxidizer. The method further includes receiving the desorbed analyte via an analyzer of the analyte detection system.

The invention belongs to the technical field of inorganic porous materials, and particularly relates to a magnesium hydride hydrogen storage composite material containing a porous material and a preparation method thereof. The magnesium hydride hydrogen storage composite material containing the porous material is formed by compounding magnesium hydride and the porous material, the weight ratio ofthe magnesium hydride to the porous material is (0.1-1.2): 1, the porous material is one or more of graphite, SiO2 or Al2O3, and The method comprises the following steps: mixing the magnesium hydridewith the porous material; and compressing the mixture to form the magnesium hydride hydrogen storage composite material. According to the invention, the porous material with adjustable aperture is used as a carrier, so that the hydrogen storage performance of magnesium hydride is combined with excellent pore channels, high specific surface area and the like of the porous material, and the hydrogenstorage material has good characteristics in the aspects of hydrogen adsorption and desorption kinetics. The hydrogen storage material is compositely formed in a compression mode, the hydrogen storage density per unit volume can be improved, and the mechanical strength is improved.

The invention relates to a high-performance high-capacity hydrogen storage alloy for a fuel cell and a preparation method of the hydrogen storage alloy. The chemical composition of the hydrogen storage alloy is expressed as Mg80+x(Ce, Y)a(Ni, Co)b according to an atomic ratio, wherein x is greater than or equal to 0 and less than and equal to 15, a is greater than or equal to 0 and less than and equal to 10, and b is greater than or equal to 5 and less than and equal to 20; and a+b is greater than or equal to 5 and less than and equal to 20. The alloy has a double-platform collaboration mechanism. According to the preparation method, a 3+1 metallurgy method, a two-step smelting method and a one-step ball milling method are adopted, volatilization of magnesium is effectively inhibited, theuniformity of alloy components is guaranteed, meanwhile, solid solution of Mg-Ni and Mg-Co compounds is avoided, and two single magnesium compounds can be generated. After repeated hydrogenation, an Mg2Ni/Mg2NiH4 cycle with high platform pressure and an Mg6Co2H11/Mg2CoH5 cycle with low platform pressure are formed. The Mg/MgH2 is induced to preferentially nucleate by double platforms, so that themechanical properties are improved, and the reaction temperature is reduced. The hydrogen absorption capacity of the hydrogen storage alloy is larger than 5 wt.%, and the hydrogen storage alloy has fast hydrogen absorption and desorption kinetics and is expected to become a solid hydrogen source of the fuel cell.

Achieving the selective and reversible adsorption of CO2 from humid, low partial pressures streams such as the flue gas resulting from the combustion of natural gas in combined cycle power plants (4%CO2) is challenging due to the need for high thermal, oxidative, and hydrolytic stability as well as moderate regeneration conditions to reduce the energy of adsorption/desorption cycling. Appending cyclic primary, secondary diamines, exemplified by 2-(aminomethyl)piperidine (2-ampd), to the metal-organic frameworks Mg2(dobpdc) (dobpdc4- = 4,4-dioxidobiphenyl-3,3-dicarboxylate), Mg2(dotpdc) (dotpdc4- = 4,4''-dioxido-[1,1':4',1''-terphenyl]-3,3''-dicarboxylate) or Mg2(pc-dobpdc) (pc-dobpdc4- = dioxidobiphenyl-4,4'-dicarboxylate) produces adsorbents of the classes EMM-44, EMM-45, and EMM-46, respectively, that display step-shaped adsorption of CO2 at the partial pressures required for 90% capture from natural gas flue gas at temperatures up to or exceeding 60 DEG C. Using a cyclic diamine inplace of a diamine functionalized with bulky alkyl groups enables fast adsorption/desorption kinetics with sharp CO2 adsorption and desorption steps.

The present invention provides an apparatus for manufacturing stoichiometric Mg₂Ni compound applicable to industry and capable of manufacturing continuously. The apparatus mainly comprises: a vacuum chamber, comprising a material feeding tube; a first crucible, set in the vacuum chamber; a heating device, set on the first crucible; a stirring device, set in the vacuum chamber, and above the first crucible; and a second crucible, set in the vacuum chamber, and on one side of the first crucible. The present invention also discloses a method to manufacture stoichiometric γ-phase Mg₂Ni hydrogen storage compound. Through this apparatus and method, the residual waste magnesium-rich liquid in the crucible is poured to another independent crucible, and switch with the position of the crucible originally containing the γ-phase Mg₂Ni hydrogen storage compound. Then, new raw materials of magnesium and nickel are added and heated. Repeat the smelt steps described above continuously, and a continuous manufacturing method is introduced. After the original crucible is cooled, the solid substances at the bottom of the crucible can be tapped down without further special treatments. Then stoichiometric γ-phase Mg₂Ni hydrogen storage compound with an exactly atomic ratio of 2:1, without other phases, and with excellent hydrogen absorption-desorption dynamics is given.

The present invention provides a method and apparatus for manufacturing high-purity hydrogen storage alloy Mg₂Ni applicable to industry and capable of manufacturing continuously. First, raw materials of magnesium-nickel with weight percentage of nickel between 23.5 and 50.2 are heated, melt, and mixed uniformly. Cool the magnesium-nickel liquid and control the temperature to be above the solidification temperature and below the liquification temperature in the phase diagram of magnesium-nickel. By making advantage of segregation principle in phase diagrams, solid-state high-purity γ-phase Mg₂Ni hydrogen storage alloy is given. The residual waste magnesium-rich liquid in the crucible is poured to another independent crucible, and switch with the position of the crucible originally containing the γ-phase Mg₂Ni hydrogen storage alloy. Then, new raw materials of magnesium and nickel are added and heated. Repeat the smelt steps described above continuously, and a continuous manufacturing method is introduced. After the original crucible is cooled, the solid substances at the bottom of the crucible can be tapped down without further special treatments. Then high-purity γ-phase Mg₂Ni hydrogen storage alloy with atomic ratio of 2:1, no other phases, and with excellent hydrogen absorption-desorption dynamics is given.

The invention discloses an efficient vanadium nitride/molybdenum carbide heterojunction hydrogen production electrocatalyst and a preparation method and application thereof. The electrocatalyst has a heterojunction structure formed by coupling VN and Mo2C, wherein the mass ratio of VN to Mo2C is (20: 1)-(50: 1). According to the catalyst, nano VN and Mo2C are coupled to form a VN/Mo2C heterojunction, so that active centers are increased, the balance of H < + > adsorption/H2 desorption kinetics is facilitated, and the activity of the catalyst is improved to a great extent.

The invention discloses a 1, 1 '-ferrocene dicarboxylic acid ligand exchanged hollow MIL-101 metal organic framework material as well as a preparation method and application thereof, the preparation method comprises the following steps: (1) preparing an MIL-101 metal organic framework material, and performing acid etching on the MIL-101 metal organic framework material to obtain the hollow MIL-101 metal organic framework material; and (2) dispersing the hollow MIL-101 metal organic framework material and 1, 1 '-ferrocenedicarboxylic acid into a solvent, adding acetic acid, uniformly mixing to form a suspension, reacting at 80-160 DEG C for 6-24 hours, cooling, centrifuging, washing and drying to obtain the hollow MIL-101 metal organic framework material exchanged by the 1, 1'-ferrocenedicarboxylic acid ligand. The ligand-exchanged hollow MIL-101 metal organic framework material has the characteristics of large specific surface area, high water adsorption capacity, rapid adsorption and desorption kinetics, excellent light absorption and photothermal conversion capability, outstanding antibacterial performance and the like, and can be used in the fields of solar-driven atmospheric water collection, fruit and vegetable preservation, intelligent sterilization and the like.

The invention discloses a method for establishing a dynamic desorption model of plutonium on a mineral surface, which comprises the following steps: carrying out dynamic desorption experiments of plutonium at different flow velocities, obtaining key parameters of the plutonium desorption experiments, deducing a kinetic reaction equation of the desorption of plutonium on the mineral surface, and establishing the dynamic desorption model of plutonium. The method can be suitable for the desorption behavior research of the nuclide plutonium on the surface of each rock mine in various scenes, the desorption amount of the nuclide at different flow velocities along with time change is obtained according to the desorption model, and a support is provided for the prediction of the desorption behavior of the plutonium in a large-scale time range.

The invention discloses a Ti-Fe based porous hydrogen evolution cathode material and a preparation method and application. Ti Fe based hydrogen storage alloy powder is taken as a raw material, a hydrogen evolution cathode matrix is prepared by adopting a solid-phase sintering method, and then is subjected to coating modification to obtain the final hydrogen evolution cathode material, and is usedas a cathode material in the hydrogen production by water electrolysis. On the one hand, the matrix has porous properties and large surface area, so that more reaction interfaces can be provided for the hydrogen evolution process of an electrode, and the reaction is easier; the porous matrix is modified with a Ni based alloy coating with high catalytic activity, the activation energy of the reaction can be further reduced, and the hydrogen evolution point location and energy consumption are reduced; on the other hand, the matrix has large hydrogen storage capacity and good room temperature hydrogen absorption and desorption kinetics performance, in normal electrolytic hydrogen production, part of hydrogen can be absorbed into an alloy, and in case of power failure, the absorbed hydrogen can be transferred to the electrode surface through diffusion, the electrode components are replaced to generate oxidation reaction, so that the electrode material can be protected.