437 results about "Catalyst selectivity" patented technology

A method for improving the selectivity of a supported highly selective epoxidation catalyst comprising silver in a quantity of at most 0.17 g per m² surface area of the support, which method comprises

• • contacting the catalyst, or a precursor of the catalyst comprising the silver in cationic form, with a feed comprising oxygen at a catalyst temperature above 250° C. for a duration of up to 150 hours, and
  • subsequently decreasing the catalyst temperature to a value of at most 250° C.; and

a process for the epoxidation of an olefin, which process comprises

contacting a supported highly selective epoxidation catalyst comprising silver in a quantity of at most 0.17 g per m² surface area of the support, or a precursor of the catalyst comprising the silver in cationic form, with a feed comprising oxygen at a catalyst temperature above 250° C. for a duration of up to 150 hours, and

subsequently decreasing the catalyst temperature to a value of at most 250° C. and contacting the catalyst with the feed comprising the olefin and oxygen.

The invention relates to a method for preparing methylbenzene or dimethylbenzene by alkylating benzene with methanol, comprising the following steps: raw material benzene and recycle benzene rectified to be recovered are mixed together with the methanol, mixed materials exchange heat with materials on an outlet of an alkylation reactor, and then the mixed materials are heated to achieve alkylation reaction temperature and subject to alkylation reaction to obtain a product under the condition that an acidic catalyst exists; the product is cooled by water to reduce temperature and then subjects to oil-water separation to obtain a water phase and an oil phase, wherein the water phase is purified to be recycled, the oil phase is rectified to be separated to obtain the benzene, the methylbenzene and the dimethylbenzene, and the methylbenzene and the dimethylbenzene are used as target products to separate from a reaction system; and unreacted benzene is returned to be circulated and continuously reacted together with the raw material benzene. The invention has high catalyst selectivity and can conveniently regulate the selectivity of the methylbenzene and the dimethylbenzene.

The invention relates to a catalyst for producing dimethylbenzene by alkylation of benzene and methanol. The catalyst mainly overcomes the shortcomings of low utilization rate of methanol alkylation, low conversion rate of benzene and low selectivity of dimethylbenzene in the actual application of the catalyst reported in previous literatures. Through the adoption of the technical scheme of loading alkaline earth and rare-earth metal elements on a hydrogen-type MCM-22 molecular sieve, the problem is well solved. The catalyst provided by the invention is high in selectivity and can be used in the production process of dimethylbenzene by alkylation of benzene and methanol.

The invention provides a three-layer multi-metal oxide catalyst and a preparation method thereof. The catalyst contains various metal oxides which are taken as active ingredients; and the composition of the active ingredients can be expressed by the following general formulas: MoaBibNieCogSihAiBjCkOx (I), MoaBibNieTifOm (II) and MoaBibSicAldOn (III). The catalyst is applicable to the process of producing corresponding unsaturated aldehyde by selectively oxidizing propylene or isobutene, and can effectively prevent a large number of byproducts from being generated because high-concentration organic substances in feed gas are initially contacted with the catalyst to form higher hot spots, so that the selectivity of catalyst is improved.

To provide a temperature sensor plausibility diagnosis unit and plausibility diagnosis method that can accurately perform plausibility diagnosis of a temperature sensor in a desired timing and an exhaust purification apparatus equipped with the plausibility diagnosis unit.

A temperature sensor plausibility diagnosis unit which, in an exhaust purification apparatus of an internal combustion engine that delivers an additive inside a storage tank to an exhaust pipe on the upstream side of a reduction catalyst and selectively reduces and purifies NO_x in exhaust with the reduction catalyst, is for performing plausibility diagnosis of a temperature sensor disposed inside the storage tank, the temperature sensor plausibility diagnosis unit being equipped with an additive heat capacity calculating portion that calculates the heat capacity of the additive inside the storage tank, a heat quantity variation calculating portion that calculates an increase or decrease in the quantity of heat that the additive inside the storage tank receives, and a plausibility diagnosing portion that determines the plausibility of the temperature sensor by comparing an estimated temperature course of the additive estimated from the heat capacity of the additive and the increase or decrease in the quantity of heat with a sensor temperature course of the additive detected by the temperature sensor.

The invention concerns a process for selective hydroisomerization of compounds with an n-alkane chain containing more than 10 carbon atoms, in which the compound to be treated is brought into contact with a catalyst comprising at least one hydro-dehydrogenating element and at least one molecular sieve having a one- or two-dimensional pore network, the accessible pore openings of which are delimited by 10 oxygen atoms, and a distance termed the bridging distance between the pores of less then 0.70 nm, and the zeolite is such that a catalyst which undergoes a standard n-heptadecane isomerization test has, for a conversion of 95%, a selectivity of at least 70% for isomerized products, and the catalyst contains at least 5% by weight of at least one hydro-dehydrogenating element selected from the group formed by non noble GVIII metals, GVIB metals, and niobium, and the catalyst preferably contains phosphorous.The sieve is preferably a NU-10, NU-23, NU-87, EU-13 or Theta-1 zeolite.

This invention relates to a catalyst and process for selectively hydrodesulfurizing naphtha feedstreams using a catalyst comprising at least one hydrodesulfurizing metal supported on a low acidity, ordered mesoporous support material.

The present invention discloses a low energy consumption hydrocracking method for producing a high-quality jet fuel. According to the method, a raw material oil and hydrogen gas are mixed, then are subjected to heat exchange two times, and then sequentially pass through a hydrorefining reaction zone and a hydrocracking reaction zone, wherein the hydrocracking reaction zone comprises at least two hydrocracking catalysts, the upstream is filled with a catalyst I, the downstream is filled with a catalyst II, the catalyst I contains 15-50 wt% of a modified Y molecular sieve, the catalyst II contains 3-30 wt% of the modified Y molecular sieve, and the modified Y molecular sieve content in the catalyst I is 10-25% higher than the modified Y molecular sieve content in the catalyst II. According to the method of the present invention, the high temperature high pressure countercurrent heat transfer technology and the hydrocracking catalyst grading technology are organically combined, and the hydrocracking reaction heat is comprehensively utilized, such that the characteristics of the two different types of the hydrocracking catalysts are completely provided, and the catalyst selectivity is maintained while the target product quality is improved, and the project investment and the operating energy consumption are reduced.

A polyolefin polymer comprising one or more terminal polymerizable methacryloyl groups (i.e. tethered to the main body of the polymer) and a novel process for preparing same are herein disclosed. A hyperbranched polyethylene polymer and a process for preparing same are also disclosed. The polymer is prepared by a novel one-pot copolymerization reaction of an olefin, such as ethylene, and a heterobifunctional comonomer comprising a methacryloyl group, catalyzed by a late transition metal α-diimine catalyst which is selectively non-reactive towards methacryloyl groups. The process allows for preparation of polymers with various chain topologies, including linear, branched, and hyperbranched topologies. The terminal methacryloyl groups within the polymer are reactive in further polymerization reactions. Thus, the polymer may be used in materials and applications which require cross-linking or further polymerization, for example, UV/thermal/radical curable crosslinkers for use in thermoset applications.

The invention discloses a treatment method for improving the selectivity of a catalytic cracking catalyst, which comprises the following steps: filling a fresh catalyst into a phase fluidized bed, contacting the fresh catalyst with aging medium containing water vapor, aging under a certain hydrothermal condition to obtain an aged catalyst; and adding the aged catalyst into an industrial catalytic cracking device. In the method, the activity and selective distribution of the catalyst in the catalytic cracking device are more uniform to obviously improve the selectivity of the catalytic cracking catalyst, thereby obviously reducing dry gas productivity and coke productivity.

The invention discloses high-selectivity carbide catalyst for naphthalene hydrogenation reaction for preparing tetrahydronaphthalene and a quick microwave preparation method thereof, belonging to the technical field of catalyst material application and preparation. The method comprises the steps of: fully grinding complex compounds containing relevant metals and carriers, or supporting the complex compounds containing the relevant metals onto the surfaces of carriers through a solution impregnation method and conducting microwave pyrolysis in inert gas to form the supported carbide catalyst. The invention provides the high-efficiency carbide catalyst with 100 percent selectivity aiming at the naphthalene hydrogenation reaction for preparing the tetrahydronaphthalene and a simple, convenient, quick, environmental-friendly and energy-saving preparation method thereof. The prepared carbide particles are evenly dispersed on the carriers, so that the situation of surface carbon deposition is avoided. The contradiction between high catalyst selectivity and high cost is successfully avoided, and therefore the high-selectivity carbide catalyst and the preparation method thereof have promising industrial application prospect.

The invention relates to a caoline substrate composite molecule screen and relative preparation. Wherein, the invention is characterized in that: on the inner and outer surface of modified caoline micro ball which meets original position crystallization condition, there are Y molecule screen and ZSM-5 zeolite, while the relative content of Y molecule screen is 10-98%, and the ZSM-5 content is 2-90%. The invention leads Y zeolite and second molecule screen (ZSM-5 zeolite) into the inner and outer surface of micro ball, to improve the catalyst selectivity and improve the propone yield. And the invention expresses high thermal stability.

Ammonia oxidation catalyst being superior in heat resistance and capable of suppressing by-production of N₂O and leakage of ammonia. The ammonia oxidation catalyst (AMOX) removes surplus ammonia, in selectively reducing nitrogen oxides by adding urea or ammonia and using a selective catalytic reduction (SCR) catalyst, into exhaust gas, wherein the ammonia oxidation catalyst is made by coating at least two catalyst layers having a catalyst layer (lower layer) including a catalyst supported a noble metal element on a composite oxide (A) having titania and silica as main components, and a catalyst layer (upper layer) including a composite oxide (C) consisting of tungsten oxide, ceria, and zirconia, at the surface of an integral structure-type substrate, wherein a composition of the composite oxide (C) is tungsten oxide: 1 to 50% by weight, ceria: 1 to 60% by weight, and zirconia: 30 to 90% by weight.

The invention relates to a catalyst regeneration method for improving the selectivity of a catalyst. A catalyst to be regenerated is contacted with oxygen-containing gas in a first fluidized bed and generates a coke combustion reaction, the mixture of the obtained semi-regenerated catalyst and flue gas enters a second fluidized bed regenerator, is contacted with the optional oxygen-containing gas and generates the coke combustion reaction continuously, the regenerated catalyst enters a reactor, and the flue gas enters an energy recovery system of the flue gas by a cyclone separator. The distribution of the activity of the regenerated catalyst obtained by the method is more uniform, the activity of the regenerated catalyst obtained by the method more approaches to the equilibrium activity of a catalyst, part of heavy metal on the surface of the regenerated catalyst is buried by a substrate under the conditions of low temperature and long-time operation, and the rest part of the heavy metal is passivated. When hydrocarbon carries out a catalytic cracking reaction on the regenerated catalyst, the yields of dry gas and coke are obviously lowered.

The invention discloses a method for electrocatalytic reduction of carbon dioxide. The method comprises the following steps: a three-electrode system is put in electrolyte containing carbon dioxide for electrolysis; the three-electrode system comprises a working electrode, a counter electrode and a reference electrode, wherein the counter electrode is a platinum chip electrode; the reference electrode is a saturated calomel electrode; the working electrode is a glassy carbon electrode after electrode modification; the electrode modification process is to modify the glassy carbon electrode by adopting a modifying agent through a chemical deposition method; and the modifying agent contains a ZIF-8 material or a modified ZIF-8 material. The ZIF-8 materials from different start zinc sources or the modified ZIF-8 materials calcined at different temperatures are applied to different electrolyte anions for electrocatalytic reduction of CO2; and the ZIF-8 materials or the modified ZIF-8 materials are used as electrocatalysts to achieve good selectivity, high efficiency and a certain stability.

An aftertreatment system to treat exhaust gas from a diesel engine is provided. The aftertreatment system comprises a selective catalytic reduction catalyst on a diesel particulate filter (SCR-F); a first reductant injector connected to an exhaust gas passage upstream of the SCR-F; a downstream diesel oxidation catalyst (DOC) disposed downstream of the SCR-F; a selective catalyst reduction catalyst (SCR) disposed downstream of the downstream DOC; a second reductant injector coupled to an exhaust gas passage positioned between the downstream DOC and the SCR; and a controller to determine a desired particulate matter (PM) oxidation in the SCR-F and a desired system NOx conversion based on engine conditions, and to control a first reductant flowrate from the first reductant injector and a second reductant flowrate from the second reductant injector based on the desired PM oxidation in the SCR-F and the desired system NOx conversion.

A phthalate-free catalyst component for olefin polymerization comprising titanium, magnesium, a halogen, diether, and oxalic acid diamides represented by the following formula (I):

and an olefin polymerization catalyst system consisting of the solid catalyst component, an organoaluminum compound, and an optional external electron donor compound. The present catalyst compositions improve diether-based catalyst selectivity while maintaining excellent catalyst activity and hydrogen response. An olefin polymer that has a moderate molecular weight distribution while maintaining higher stereoregularity (isotacticity) over diether-based catalyst, and better than or equal to phthalate-based catalyst can be produced by utilizing the inventive catalyst component.

The invention relates to systems and methods for treating oxygen-rich NO_x-containing exhaust. The systems and methods comprise using first and second NO_x reducing catalysts. According to one aspect of the invention, the first catalyst reduces NO_x in oxygen-rich exhaust primarily through reaction with a first reductant species and the second catalyst reduces NO_x in oxygen-rich exhaust primarily through reaction with a second reductant species. Collectively, the two catalysts are substantially more effective than either of the catalysts individually in reducing the concentration of NO_x in the exhaust. According to another aspect of the invention, an exhaust system is configured to inject a first reductant species primarily at a first location upstream of the first NO_x reducing catalyst, and is configured to inject a second reductant species primarily at a second location downstream of the first NO_x reducing catalyst, but upstream of the second NO_x reducing catalyst.

The invention discloses a hydrocracking method of low-energy-consumption, productive and high-quality jet fuel. The hydrocracking method comprises the steps that after being mixed with hydrogen, raw oil undergoes heat exchange twice, passes through hydrofining and first cracking reaction zones in sequence after passing through a heating furnace and is separated to obtain middle distillate, and the middle distillate enters a second cracking reaction zone to be cracked, wherein the first cracking reaction zone at least comprises two cracking catalysts, namely an upstream filling catalyst I and a downstream filling catalyst II; the catalyst I contains 15-50wt% of modified Y molecular sieve; the catalyst II contains 3-30wt% of modified Y molecular sieve; the content of the modified Y molecular sieve in the catalyst I is higher than the content of the modified Y molecular sieve in the catalyst II by 10-25%. The hydrocracking method has the advantages that the high temperature and high pressure countercurrent heat transfer technology and the hydrocracking catalyst grading technology are organically combined and the hydrocracking reaction heat is comprehensively utilized, thus improving the quality of the target product and reducing the project investment and the operation energy consumption while maintaining the selectivity of the catalysts.

The molecular sieve catalyst for synthesizing methanol into durene is ZSM-5 type with molar Si/Al ratio of 13-50, strong/weak acid ratio of 1.03-1.30, adsorption amount to cyclohexane of 5.95-6.25 wt%, said adsorption amount to n-hexane of 8.95-9.15 wt%. The hydrogen-type molecular sieve, assistant and nitric acid are mixed and kneaded, and the mixture is formed, stoved, crushed, roasted, soakingin acid solution, stoved and roasted to obtain the catalyst. The present invention has the advantages of simple preparation process, high selectivity of the catalyst, and the durene content in the product as high as 20%.