16 results about "Selective catalyst" patented technology

The invention relates to a modified Fe-Mo series formaldehyde catalyst and a method, the active component of the catalyst is metal salt of Fe and Mo, the auxiliary agent is salt of one or more metals M selected from K, Mg, Al, Ba and Ni, the mass ratio of M is 0.1-5%, the preferential amount of K is 0.1-0.5%, the preferential amount of Mg is 0.1-1.5%, the preferential amount of Al is 1.0-3.5%, the preferential amount of Ba is 1.0-3.5%, and the preferential amount of Ni is 2-5.0%. According to the preparation method of the catalyst, a coprecipitation method is adopted, the prepared catalyst is wide in pore size distribution by controlling the reaction speed of coprecipitation, and then the catalyst is pressed into a hollow cylinder shape or a four-leaf clover shape. According to the catalyst, the conversion rate of methanol and the selectivity of formaldehyde are improved, and the stability of the catalyst is good.

The application relates to the field of organic chemistry, in particular to a method for photocatalytic synthesis of silanol or silyl ether. The application provides a method for photocatalytic synthesis of silanol or silyl ether compound, in which, under the condition of existence of an iridium catalyst and an organic solvent, hydrosilane is reacted with any one of water, alcohol or phenol under light to obtain silanol or silyl ether. The synthesis method has high yield and selectivity, low catalyst consumption, mild reaction condition and high environmental protection and efficiency.

The application discloses a shape-selective catalyst for preparing 4,4'-disubstituted diphenylmethane by alkylation and a preparation method and application thereof. The catalyst is composed of a molecular sieve and an oxide for modifying the molecular sieve. The oxide is an oxide corresponding to the highest valence of a modified element. The modified element includes phosphorus, titanium, zirconium, gallium, indium, germanium, molybdenum, tungsten, rhenium or copper. The mass content of the oxide in the catalyst is 0.01-20% in the catalyst with a mass of 100%. The catalyst has good thermal stability and chemical stability, can be repeatedly used, has a simple regeneration method and a high activity recovery rate.

The invention provides a C3 fraction selective catalyst. The catalyst comprises a carrier and an active component loaded on the carrier, wherein the carrier is a metal composite oxide modified by an organic cation quaternary ammonium salt and a silane reagent; the metal element I in the metal composite oxide comprises aluminum and titanium; the metal element II in the active component comprises a main active component noble metal Pd and an optional auxiliary active component, the auxiliary active component comprises transition metal and / or alkaline earth metal, the transition metal is selected from one or more of Cu, Mn, Ni and Zn, and the alkaline earth metal is selected from one or more of Ca, Mg and Ba. The carrier is modified through the organic cation quaternary ammonium salt and the silane reagent, the dispersity of active components on the surface of the carrier can be remarkably improved, and the problem that the crushing strength of metal composite oxide is low is solved. The invention also provides a preparation method and application of the C3 fraction selective catalyst, and also provides a method for producing propylene through selective hydrogenation of C3 fractions.

A catalyst A with isotactic selectivity and a catalyst B with random selectivity are selected to form a binary catalytic system, and the allyl block polyolefin elastomer is efficiently synthesized through chain shuttling polymerization. The melting point and the glass-transition temperature of the allyl block polyolefin elastomer can be conveniently regulated and controlled by changing the isotacticity and introducing the content of the comonomer, the melting point range is 100-160 DEG C, and the glass-transition temperature range is-50-0 DEG C. The prepared propenyl block polyolefin elastomer is novel in structure and excellent in performance and has original innovativeness.

The invention discloses a method for preparing 4, 4 '-dihydroxybenzaldehyde through alkylation The invention discloses a shape-selective catalyst based on 4, 4 '-disubstituted diphenylmethane and a preparation method and application thereof, the catalyst is composed of a molecular sieve and an oxide for modifying the molecular sieve, the oxide is an oxide corresponding to the highest valence of a modification element, and the modification element comprises phosphorus, titanium, zirconium, gallium, indium, germanium, molybdenum, tungsten, rhenium or copper; the mass of the catalyst is 100%, the oxide accounts for 0.01-20% of the mass of the catalyst, and the balance is the molecular sieve. The catalyst has the advantages of good thermal stability, good chemical stability, reusability, simple regeneration method and high activity recovery rate.

A method for controlling the operation of a hydrogen combustion engine system of a vehicle. The hydrogen combustion engine system has a hydrogen combustion engine and an EATS to reduce emissions in the engine exhausts. The EATS has a selective catalyst reduction, SCR, catalyst and an ammonia slip catalyst, ASC, arranged downstream of the SCR catalyst. The method comprises: determining the temperature of the SCR catalyst; determining the temperature of the ASC; in response of determining that the temperature of the SCR catalyst is below a predetermined SCR temperature threshold value, and that the temperature of the ASC is below a predetermined ASC temperature threshold value, operating the hydrogen combustion engine in an H2 exhaust excess mode defined by an amount of unburnt H2 of at least 0.2 mol % in the engine exhausts, and using the unburnt H2 in the engine exhausts as a reductant for NOx conversion in the ASC.

The application discloses a kind of nitrogen-doped carbon modified Ni / MgAlO catalyst and its preparation method and application, belong to catalytic technology field.The present application is with magnesium source, aluminium source, nickel source and hexamethylene tetramine as raw material, by hydrothermal reaction and calcination preparation NiO / MgAlO, then with hydrochloric acid dopamine as carbon source to its surface modification, again carbonization treatment under nitrogen atmosphere, preparation Ni / MgAlO catalyst.Carbonization introduced carbon modifier and nickel exist strong electronic interaction, and through the same kind of repulsion effect mechanism accelerates the migration rate of carbon produced by methane cracking on the surface of nickel particle, reduce the formation of coated carbon, enhance the catalytic activity and hydrogen selectivity of catalyst;Carbon modifier on the surface of catalyst prevents methane cracking generated carbon from directly covering the surface of nickel particle, while inhibiting nickel particle sintering agglomeration at high temperature, enhances the catalytic stability of nickel.

An exhaust aftertreatment unit for cleaning exhaust gases, the exhaust aftertreatment unit including a fluid channel for providing a fluid pathway for the exhaust gases, the fluid channel having an outer casing; a catalyst casing housing a selective catalyst reduction (SCR) catalyst and an ammonia slip catalyst (ASC) arranged downstream of the SCR catalyst, the catalyst casing being arranged inside the outer casing forming an intermediate space between the inner and outer casings; and a detector configured to measure ammonia and / or NOx in the exhaust gases; wherein the catalyst casing includes one or more perforations upstream of the ASC to enable a by-pass flow of exhaust gases from inside the catalyst casing into the intermediate space, and wherein the detector is arranged in the fluid channel to measure the ammonia and / or NOx in the exhaust gases including the by-pass flow.

The invention discloses a multi-metal oxide catalyst for producing ethylene carbonate by a transesterification method and a preparation method thereof, the catalyst comprises an active component and a carrier, and the active component is loaded on the carrier; the active component is selected from at least one of MgO, CuO, CaO, La2O3, NiO, CeO and BaO; the carrier is selected from at least one of active carbon (AC), gamma-Al2O3, SiO or TS molecular sieve. According to the ethylene carbonate prepared by adopting the catalyst, the EG conversion per pass is more than or equal to 80%, the EC selectivity is more than or equal to 93%, the dosage of the catalyst is 1-5wt% of the total mass of dimethyl carbonate and ethylene glycol, and the single pass life of the catalyst is more than or equal to 100h.

This application discloses an in-situ preparation method for a catalyst, comprising the following steps: gasifying a nitrogen-containing substance and / or a phosphorus-containing substance to obtain a mixed gas, passing it into a reactor containing a support, and performing heat treatment I and heat treatment II to obtain the catalyst. This method enables the uniform introduction of active components and additives, resulting in a uniform distribution of active sites in the prepared catalyst, which is beneficial for improving the catalyst's activity and selectivity. When used in the reaction of acetate and NH3, the catalyst can suppress side reactions and achieve high acetonitrile selectivity. It avoids corrosiveness to reaction equipment, provides mild reaction conditions, has high atom utilization, and is suitable for continuous, stable, and large-scale production.

The application relates to application of a high-selectivity catalyst Cu-ZnO / TiO2 in synthesis of benzimidazole in a heterogeneous system and belongs to the technical field of catalyst preparation and application. The catalyst is prepared by using zinc nitrate hexahydrate as a zinc source, copper nitrate trihydrate as a copper source and P25 type titanium dioxide as a carrier, loading ZnO and Cu on the titanium dioxide by adopting a step-by-step precipitation method, reducing in a tube furnace by hydrogen, obtaining the catalyst Cu-ZnO / TiO2, and then catalyzing o-phenylenediamine to react to synthesize benzimidazole by taking CO2 as a carbon source and hydrogen as a hydrogen source. The Cu-ZnO / TiO2 catalyst with copper and zinc oxide contents of 5% and 4% respectively has excellent catalytic performance, under the reaction conditions of a CO2 pressure of 2.5 MPa, a hydrogen pressure of 3.5 MPa and a temperature of 180 DEG C, when the conversion rate of o-phenylenediamine is 100%, the selectivity of benzimidazole is greater than 99.9%, and the TOF value is 6.4 h ‑1 . The preparation method is simple, low in cost, high in selectivity when used for catalyzing o-phenylenediamine to react with CO2 and H2 to prepare benzimidazole, and has wide industrialization prospects.

This invention discloses a method for preparing cis-1,2-dibromoethylene based on steric hindrance, belonging to the field of technical organic synthesis. The method includes the following steps: (a) providing reactors A and B connected in series. Bromine is added to reactor A, and a solvent and configuration-selective catalyst are added to reactor B. This invention employs a series reactor system. Under the synergistic effect of a copper / crown ether composite catalyst and ultraviolet light, a highly selective addition reaction of acetylene with bromine is achieved by controlling the solvent system, reaction temperature, and material ratio. Using acetonitrile or perfluoroalkane as solvent, and copper chloride and crown ethers (such as 15-crown-5) as catalysts, the reaction is carried out at 30-80℃ under 200-400nm ultraviolet light. The selectivity of cis-1,2-dibromoethylene is ≥95%, which has advantages such as mild reaction conditions, solvent recyclability, and suitability for industrial production. Furthermore, the cis selectivity is improved to ≥95%; the content of the byproduct tetrabromoethane is <0.5%; and the solvent recovery rate is >98%.

A conditioning process that is employed with a high selectivity catalyst (HSC) during an initial phase (i.e., start-up) of the epoxidation process is provided. The HSC conditioning process of the present disclosure ensures that the heat release from a catalyst bed containing an HSC during a start-up operation is less than 2000 kJ / Kgcat.hr. The HSC containing catalyst bed that has been conditioned by the process of the present disclosure exhibits improved performance (i.e., EO selectivity) and reduced hot spots.

A method for controls the operation of a hydrogen combustion engine system of a vehicle including a hydrogen combustion engine and an exhaust aftertreatment system, EATS, to reduce emissions in the engine exhausts. The EATS comprises a selective catalyst reduction, SCR, catalyst and an ammonia slip catalyst, ASC, arranged downstream of the SCR catalyst. The method includes: identifying a regeneration time window for performing regeneration of the ASC; in response of identifying the regeneration time window, operating the hydrogen combustion engine in an H2 exhaust excess mode defined by an amount of unburnt H2 of at least 1.5 mol % in the engine exhaust and regenerating the ASC by using the unburnt H2 in the engine exhausts and reaching a regeneration temperature of at least 500° C.

An engine system includes a hydrogen combustion engine and an exhaust aftertreatment system, EATS, configured to reduce emissions of the engine exhausts. The EATS comprises: an exhaust gas inlet for receiving engine exhaust from the hydrogen combustion engine; a plurality of emission reducing modules arranged downstream of the exhaust gas inlet and being configured to reduce emissions of the engine exhausts, the plurality of emission reducing modules comprising at least a first emission reducing module with a porous substrate including a powder coating and a selective catalyst reduction, SCR, coating, and a second emission reducing module being a selective catalyst reduction, SCR, catalyst unit. At least one of the first and second emission reducing modules is arranged as the first occurring emission reducing module of the EATS downstream of the exhaust gas inlet.