543 results about "Silver catalyst" patented technology

A catalyst system and a method for reducing nitrogen oxides in an exhaust gas by reduction with a hydrocarbon or oxygen-containing organic compound reducing agent are provided. The catalyst system contains a silver catalyst and a modifier catalyst, where the modifier catalyst contains a modifier oxide, where the modifier oxide is selected from the group consisting of iron oxide, cerium oxide, copper oxide, manganese oxide, chromium oxide, a lanthanide oxide, an actinide oxide, molybdenum oxide, tin oxide, indium oxide, rhenium oxide, tantalum oxide, osmium oxide, barium oxide, calcium oxide, strontium oxide, potassium oxide, vanadium oxide, nickel oxide, tungsten oxide, and mixtures thereof. The modifier oxide is supported on an inorganic oxide support or supports, where at least one of the inorganic oxide supports is an acidic support. The catalyst system of the silver catalyst and the modifier catalyst provides higher NO_x conversion than either the silver catalyst or the modifier catalyst alone.

The invention involves alumina carrier used for Ag catalyst which is used for produce epoxyethane with oxygenizing ethane and its preparation method the Ag catalyst prepared by the carrier, and relates to the usage of the catalyst in ethane oxygenizes epoxyethane. The preparation method mixes three-hydratedalpha-aluminum oxide with certain particle size, hydratedalpha-aluminum oxide, certain amount of inflammable carbonaceous material, fluxing agent, fluoride and optional heavy alkaline earth metal compounds, adds admixture and water after mixing uniformly, kneading uniformly, squeezing and shaping, then preparingalpha-alumina carrier after drying and roasting. The specific surfaceof the invention is 0.2- 2.0m2/g, the hole volume is 0.35-0.85ml/g, water absorption ratio>=30%, crushing strength is 30-120N/ particle. The carrier is dipped by the solution of silver ammine complex, alkaline metal compound and alkaline earth metal compound, and prepares the Ag catalyst for epoxyethane with oxygenizing ethane after drying and activating.

A supported silver catalyst and use thereof in a process for producing an alkylene oxide, such as ethylene oxide, by the direct oxidation of an alkylene with oxygen or an oxygen-containing gas, wherein the catalyst provides improved stability and improved resilience to reactor upsets and timely recovery to substantially pre-upset levels of catalyst activity and/or efficiency. In some embodiments, the catalyst also exhibits improved activity. A catalyst capable of producing ethylene oxide at a selectivity of at least 87 percent while achieving a work rate of at least 184 kg/h/m3 at a temperature of no greater than 235° C. when operated in a process where the inlet feed to a reactor containing the catalyst comprises ethylene, oxygen, and carbon dioxide, wherein the concentration of carbon dioxide in the inlet feed is greater than or equal to 2 mole percent.

The invention discloses a supported nano-silver catalyst capable of eliminating formaldehyde at room temperature. The catalyst uses ZSM-5 molecular sieves as carrier, and is prepared by supported nano-silver active components through metallic oxide modifying. The catalyst is composed of, by weight, 1% to 5% of nano-silver active components, 1% to 20% of metallic oxide, and 75% to 98% of ZSM-5 molecular sieves. The invention discloses a preparation method of the supported nano-silver catalyst capable of eliminating the formaldehyde at room temperature. The preparation method is characterized by comprising the following steps: the ZSM-5 molecular sieve carrier is modified, and drying and roasting are carried out to obtain the finished catalyst after the modified carrier is put into a solution to carry out equivalent-volume impregnation at 10 DEG C to 60 DEG C. The airspeed of the catalyst at room temperature is 10000 h-1 hour, the formaldehyde removal rate of the catalyst is up to more than 93.7%, the formaldehyde is catalyzed to be oxidated into harmless water and carbon dioxide to achieve green elimination, and a preparation process is simple, easy to operate, low in cost, and free of secondary pollution.

A process for the production of an olefin oxide, which process comprises reacting a feed comprising an olefin and oxygen in the presence of a silver-containing catalyst, wherein before the catalyst has reached an advanced stage of ageing the reaction temperature is above 255° C. and the olefin content of the feed is above 25 mole-%, relative to the total feed.

The present development relates to a catalyst composition for the selective hydrogenation of acetylene and to a method for preparing the catalyst. The catalyst comprises iridium, palladium and, optionally, at least one of the elements selected from the group consisting of silver, gold, copper, zinc and tin. In a preferred embodiment, the catalyst is prepared such that the palladium is located within the first 250 micrometers of the surface of the catalyst carrier. In contrast to the catalysts of the prior art, including for example, palladium/silver catalysts, the catalyst of the present invention exhibits high selectivity and an improved stability of the catalytic performance over an extended period of time.

The invention relates to an aluminum oxide carrier for catalyzing ethylene to have epoxidation in gas and solid phases to produce ethylene oxide (EO), a preparation method thereof, a silver catalyst prepared by using the preparation method and application thereof in producing the EO. The silver catalyst contains an effective catalytic quantity of silver, one or more optional alkali metal mixtures, optional alkaline-earth metals or a mixture thereof, an optional rhenium aid and an alpha-aluminum oxide carrier treated through hydrofluoric acid. When the carrier and the obtained silver catalyst are used for the epoxidation of the ethylene for preparing the EO, the carrier and the obtained silver catalyst have higher activity and selectivity and long-term stability.

The present invention relates to a preparation method for an alumina carrier. The method comprises: (a) mixing alpha-aluminum trihydroxide, pseudo aluminum monohydrate, an alkaline earth metal salt, an optionally burnout carbon-containing material, an optionally fluoride, a binder and water; (b) carrying out extruding and forming; (c) carrying out drying at a temperature of 60-200 DEG C; (d) carrying out baking at the temperature of 1200-1600 DEG C, such that alpha-aluminum oxide is prepared by transformation to obtain a semi-finished carrier;; (e) adopting an organic acid aqueous solution to treat the resulting semi-finished carrier from the step (d), wherein the organic acid can be subjected to thermal decomposition, and the pH value of the organic acid aqueous solution is not more than 2.5; (f) carrying out water washing for the resulting treated carrier from the step (e) until the pH value of the leaching solution is more than 5; and (g) carrying out a further heat treatment at the temperature of 80-1200 DEG C. The present invention further relates to the aluminum oxide carrier prepared by the method, a silver catalyst containing the carrier, and an application of the silver catalyst. With adopting the silver catalyst in preparation of ethylene oxide by the ethylene epoxidation reaction, the improved selectivity is provided.

The invention relates to catalyst preparation, and aims to provide a preparation method of catalysts for oxygen production implemented through the decomposition of hydrogen peroxide. The method comprises the following steps of: immersing a nickel-foam solid sample into a silver nitrate solution, heating the obtained object, carrying out a replacement reaction, and cooling the obtained product to room temperature; taking an alkaline sodium borohydride solution, reducing nickel ions in the previous solution to metal nickel and depositing the metal nickel to the solid sample; and taking out the solid sample, calcinating the solid sample for 2-5 hours under nitrogen so as to obtain a silver catalyst taking nickel foam as a carrier. According to the invention, micropores of nickel foam are used as oxygen transport channels, so that the service life of the catalyst is greatly prolonged. Meanwhile, because the structure compatibility of nickel and silver is excellent, and silver atoms are dissolved in the crystal structure of nickel so as to form a solid solution, so that the mechanical strength of nickel foam can be enhanced, and the capability of a carrier to resist shock waves produced by the generation of oxygen is increased, thereby greatly improving the stability and reliability of catalysts.

The invention relates to a preparation method of a porous alpha-alumina carrier of a silver catalyst used for ethylene oxide production by virtue of ethylene oxidation. The method is characterized in that before a formed body is formed, and a titanium silicalite is added into a formed body raw material. The silver catalyst prepared by the carrier which is prepared by the method shows excellent epoxidation capability and activity in the process of preparing ethylene oxide by virtue of ethylene oxidation. The invention also relates to the carrier prepared by the method, the silver catalyst prepared by the carrier, and application of the silver catalyst in ethylene oxide production by virtue of ethylene oxidation.

The invention discloses a supported silver catalyst for reducing soot particle burning temperature and a preparation method, relating to catalysts. The catalyst comprises an active component and a carrier, wherein the active component is silver; the carrier is cerium dioxide or cerium-based composite oxide; the supported amount of silver is 1-20% of the weight of the carrier; and the cerium-based composite oxide has the general formula of Ce1-xMxOy, and M is rare-earth metal. The carrier is prepared by adding a surfactant as a template into a cerium-based solution through a hydrothermal precipitation method. The catalyst is prepared by introducing a complexing auxiliary agent into a water-based silver nitrate solution, evaporating to dryness and baking. The prepared catalyst has excellent oxidative activity in the process of soot burning, is capable of reducing the temperature of soot T50 from 642 DEG C to about 400 DEG C to reach the operating temperature range of a diesel engine, and reaches and exceeds various types of reported soot particle burning catalysts under the same evaluation conditions.

The hydrocarbon-assisted, selective catalytic reduction of NO_x constituents in lean-bum engine exhaust is benefited by passage of the exhaust over a staged catalyst bed comprising a first stage of an alumina-supported silver catalyst for oxidation of NO to NO₂ and partial oxidation of added hydrocarbon to an aldehyde. Downstream of the silver catalyst is a second catalyst selected for the reaction of hydrocarbon and aldehyde species with NO₂ to reduce it to nitrogen. Gamma-alumina and BaY zeolite are examples of suitable second stage catalysts.

The invention discloses a synthetic method for a supported silver phosphate/silver catalyst. The synthetic method includes steps of weighing 1-1.2mmol of silver nitrate to prepare 10-15mmol/L of solution at first and dripping weak aqua ammonia into the solution to obtain Tollens' reagent; then weighing 20g of bentonite; adding 80-100mL of distilled water into the bentonite to immerse the bentonite for 10 hours to 12 hours so as to obtain bentonite suspension; dripping the Tollens's reagent into the bentonite suspension, stirring, ageing in water bath at the temperature ranging from 80 DEG C to 85 DEG C for 24 hours, washing by four times to five times, and adding 30-50mL of distilled water; dripping 0.01-0.1mol/L of phosphoric acid in a product, stirring for 4 hours, leading the mole ratio of the adding quantity of the phosphoric acid to the used quantity of the silver nitrate to be 1:3, ageing in water bath at the temperature ranging from 60 DEG C to 65 DEG C for 24 hours after stirring is finished, and repeatedly washing until supernate is neutral; and finally drying at the temperature of 105 DEG C, grinding, and irradiating under an xenon lamp with the power of 400-500w for 50-80 minutes so as to obtain the supported silver phosphate/silver catalyst. Utilization efficiency to natural light is increased, stability of a system is guaranteed, a nanometer laminated structure of the bentonite is utilized, accordingly, absorption ability of the catalyst and a carrier is improved, and degradation efficiency is increased.

The invention discloses a catalyst for loading silver on SiO2, a preparation method and application in a selective catalytic hydrogenation of chloro-aromatic compounds, nitryl-aromatic ene, nitryl-aromatic aldehydes, nitryl-aromatic ketone, and nitryl-aromatic polyamide. The synthetic method is that tetraethoxysilane and aminopropyl-triethoxysilane are added by weight proportion of 1: 0.1-1: 25 into an ammonia solution containing definite AgNO3, then the solution is stirred to form gelatinate under room temperature and dried under 100-200 DEG C for about 4-12 hours, thus obtaining the catalyst. The synthetic catalyst of the invention solves two problems of current catalytic hydrogenation of aromatic nitro-compounds: (1) a secondary reaction of dechlorination is generated during the hydrogenation of chloronitrobenzenes of aromatic nitro-compounds; (2) the selectivity of reaction is poor when alkene, aldehydes, ketone, nitrile and amide groups coexist.

The invention relates to a production method of methyl glycolate, aiming to mainly solve the problems of low conversion rate of dimethyl oxalate and low selectivity of methyl glycolate in the prior art. The production method of methyl glycolate comprises the following steps of (1) enabling a mixed material composed of a methanol solution of dimethyl oxalate and feed gas containing hydrogen to be in contact with a silver-containing catalyst in a reactor to react to obtain a mixture flow containing methyl glycolate, carrying out heat exchange, and then, enabling the mixture flow to enter a gas-liquid separation system; (2) sequentially carrying out condensation, primary gas-liquid separation, condensation and secondary low-temperature gas-liquid separation on the mixture flow subjected to heat exchange to obtain crude methyl glycolate; and (3) carrying out reduced-pressure distillation separation on crude methyl glycolate to obtain the methyl glycolate product. According to the technical scheme, the conversion rate of dimethyl oxalate can be higher than 99%, the selectivity of methyl glycolate can be higher than 80%, and the production method can be applied to industrial production of methyl glycolate.

The present invention relates to a support for silver catalyst used in the ethylene oxide production, a preparation method for the same, a silver catalyst prepared from the same, and its use in the ethylene oxide production. The silver catalyst produced from the silver catalyst support has an improved activity, stability and/or selectivity in the production of ethylene oxide by epoxidation of ethylene.

The invention discloses an alumina supporter for a silver catalyst. The alumina supporter comprises a cylindrical basal body with a central passage, and at least three partially cylindrical valve leaflets separated at equal intervals, wherein the valve leaflets are integrally connected on the periphery of the basal body. The alumina supporter with a new shape has high surface area and porosity between the supporters, can effectively reduce the pressure drop of a catalyst bed of the reactor, optimize the flow condition in the catalyst layer, achieve better mass and heat transferring effect and improve the performance of the silver catalyst. The silver catalyst prepared by utilizing the alumina supporter has stable performance and higher activity and selectivity, and is particularly suitable for the reaction for producing ethylene oxide by ethylene oxidization.

A Ag-carried catalyst for preparing the anhyrous formaldehyde by derect dehydrogenation of methanol is prepared by sol-gel method, which includes such steps as mixing ethyl silicate with the solution of soluble Mg salt and Al salt in water or alcohol, dropping their mixture in the aqueous solution of inorganic Ag salt, gelatinizing while adding the solution of soluble Al salt for increasing the activity and selectivity of product, ageing, drying and calcining. Its advantages are high transform rate of methanol and selectivity of formaldehyde (up to 100%) and low cost.

The invention discloses a silver catalyst making method and appliance of epoxyethane, which comprises the following steps: soaking the compound with silver, organic amine, alkali metal adjuvant, cerium adjuvant, random alkali earth metal adjuvant, rhenium adjuvant and theses adjuvant solutions to sinter into porous alpha-alumina carrier; filtering; drying; activating through compound gas with oxygen to produce silver catalyst. The method possesses higher flexibility and selectivity.

The invention discloses a silicon dioxide load nanometer silver catalyst, preparation method and application in nitro compound catalytic hydrogenation reaction thereof. The preparing method comprises adding 1.0g of silicon dioxide in 20-50ml aqueous solution with 0.016g-0.064g of silver nitrate dissolved therein; stirring for 8-12 hours at 40 DEG C; adding 10-50ml of alcohol; heating up to 110 DEG C solvent thermal reaction for 8-12 hours; filtrating pale yellow solid; drying the solid at 100-120 DEG C for 8-12 hours to obtain the silicon dioxide load nanometer silver catalyst. The catalyst prepared by the invention is used for nitryl aromatic compound selective hydrogenation to prepare amido aromatic compound, and can realize complete transformation under optimization condition.

The invention is a novel supported silver catalyst for preparing anhydrous formaldehyde by direct methanol dyhydrogenation. It is prepared by a sol-gel method (SOL-GEL method), i.e. mixing a certain amount of TEOS (tetraethoxysilane) with the water or alcohol solution containging soluble Zn and Al salts, then dripping to an inorganic silver salt water solution and preparing it through gelling, ageing, drying, baking, etc. During the gelling course, the Zn and Al salt solution added make acid-alkali neutralization to some extent, which largely enhances its activity and selectivity. It not only has high catalytic activity and longer service life but also simple and convenient to prepare, having lower price and suitable for industrial application.