828results about "Hydrocarbon by isomerisation" patented technology

The invention discloses a catalyst for an n-butene isomerization reaction and a preparation method thereof, and belongs to the technical field of catalysts. The preparation method comprises the following steps: mixing a silicon source, an aluminum source, tetrapropylammonium hydroxide and water, adding boric acid, and crystallizing to obtain a seed crystal; the method comprises the following steps: mixing a silicon source, an aluminum source, pyridine and water, adding a seed crystal and ammonium fluoride, and crystallizing to obtain a core-shell type molecular sieve; adding the core-shell type molecular sieve into the bimetallic complex solution for dipping to obtain a metal-loaded type molecular sieve; adding the metal-loaded molecular sieve into a triethyl phosphine ethanol solution for treatment to obtain a phosphorus-modified molecular sieve; uniformly mixing the phosphorus-modified molecular sieve, pseudo-boehmite, sesbania powder and water, kneading, performing extrusion molding, drying and calcining to obtain the catalyst. The catalyst prepared by the invention is used for n-butene isomerization reaction, and has excellent catalytic activity and isobutene selectivity.

A process isomerizes 2,4,4-trimethylpent-2-ene to 2,4,4-trimethylpent-1-ene over a heterogeneous catalyst based on a zeolite or an ion-exchange resin. The process includes providing an input stream containing 2,4,4-trimethylpent-2-ene and 2,4,4-trimethylpent-1-ene and performing the isomerization with the input stream using a heterogeneous catalyst based on a zeolite or an ion-exchange resin. A proportion of 2,4,4-trimethylpent-2-ene in the total stream is at least 25 mol % based on the total input stream.

The invention provides a seed crystal suspension and a preparation method thereof, a preparation method of a nanoscale FER molecular sieve, and a preparation method and application of a nanoscale hydrogen type FER molecular sieve, and belongs to the field of molecular sieves. The invention provides a preparation method of a seed crystal suspension, which comprises the following steps: mixing a first silicon source, a first inorganic metal alkali source, a first aluminum source, pyrrolidine and first water to obtain first gel; performing first hydrothermal crystallization on the first gel to generate a seed crystal of which the structure is an FER molecular sieve, so as to obtain a seed crystal suspension; the temperature of the first hydrothermal crystallization is 150-180 DEG C, and the time is 10-16 hours. According to the method, pyrrolidine is selected as an organic template agent, the temperature and time of hydrothermal crystallization are adjusted, the prepared seed crystal can effectively induce the formation of crystal nucleuses when the FER molecular sieve is prepared, more initial crystal nucleuses effectively inhibit the growth of the FER molecular sieve, and the size of the FER molecular sieve is reduced.

The invention provides a nanorod-shaped ZSM-48 molecular sieve, a preparation method thereof, a hydroisomerization catalyst and application of the hydroisomerization catalyst. The synthesis method comprises the following steps: S1, uniformly mixing an alkali source, a template agent, an aluminum source, water and a silicon source, adding a seed crystal, and aging to obtain gel, with the molar ratio of hydroxyl in the alkali source to a silicon element in the silicon source being (0.01-0.09): 1; s2, carrying out first-stage crystallization on the gel at 90-110 DEG C to obtain a first-stage crystallization product; and S3, carrying out second-stage crystallization on the first-stage product at 160-190 DEG C, and carrying out post-treatment on the second-stage crystallized product to obtain the nanorod-shaped ZSM-48 molecular sieve. According to the technical scheme provided by the invention, the nanorod-shaped ZSM-48 molecular sieve with a relatively large adjustable range of a silica-alumina ratio is prepared by carrying out two-stage crystallization reaction at a specific temperature, and the nanorod-shaped ZSM-48 molecular sieve is uniform in particle morphology and relatively high in crystallinity.

The invention provides a hydroisomerization catalyst and an application thereof in an isomerization reaction of n-alkanes. The hydroisomerization catalyst comprises a Ni modified SAPO-11 molecular sieve and an active component loaded on the Ni modified SAPO-11 molecular sieve, the pore diameter of the Ni modified SAPO-11 molecular sieve is 5.4-14.5 nm, the Ni dispersity is 0.31-0.40, and the specific surface area is 195-288 m < 2 > / g.

The invention provides a method for preparing n-propylbenzene by taking n-nonane as a raw material, and relates to the technical field of organic synthesis. The method comprises the following steps: carrying out aromatization reaction on gaseous n-nonane under the action of a catalyst to obtain n-propylbenzene; the catalyst comprises a molecular sieve and metal components loaded in a molecular sieve crystal, the metal components comprise a main metal and an auxiliary metal, the main metal comprises one or more of Pd, Pt and Rh, the auxiliary metal comprises one or more of Ag, Sn, Re and Zn, and the main metal and the auxiliary metal form an alloy sub-nanocluster. According to the method, high-selectivity preparation of the n-propylbenzene is realized by utilizing the low-price n-nonane, so that the low-value n-nonane is converted into the high-value n-propylbenzene in a high-selectivity manner, and a new way is opened up for efficient preparation of the n-propylbenzene. Results of the embodiment show that by adopting the method for preparing the n-propylbenzene, the conversion rate of the n-nonane is more than 80%, and the selectivity of the n-propylbenzene is more than 75%.

The invention relates to a method for synthesizing mesitylene by gas-phase non-hydroisomerization of unsym-trimethylbenzene, which comprises the following step of: contacting the unsym-trimethylbenzene with a catalyst under a gas-phase non-hydroisomerization reaction condition in the presence of the catalyst, wherein the catalyst is an EWT structure molecular sieve, the total pore volume of the EWT structure molecular sieve is 0.20-0.51 cm < 3 >. G <-1 >, and the mesoporous volume is 0.11-0.37 cm < 3 >. G <-1 >. According to the method disclosed by the invention, the EWT structure molecular sieve with an ultra-large pore channel structure is adopted as the catalyst, and when the catalyst is used for synthesizing mesitylene through unsym-trimethylbenzene gas-phase non-hydroisomerization, the distribution conditions of raw materials and products are improved, the conversion rate of unsym-trimethylbenzene and the selectivity and the mass yield of mesitylene are improved, heavy component carbon deposition is slowed down, and the yield of mesitylene is improved. The service life of the catalyst is prolonged.

The invention discloses a catalytic method for converting alpha-olefin in an alkane-olefin mixture into internal olefin and application, raw materials and a solid acid catalyst are carried out in a fixed bed or a reaction kettle, the reaction temperature is 50-150 DEG C, the reaction pressure is 15-400 psi, and the reaction environment is an inert gas atmosphere; when the reaction is carried out on the fixed bed, the mass space velocity of the solid acid catalyst is 1h <-1 >-20h <-1 >; when the reaction is carried out in the reaction kettle, the conversion frequency of the raw materials is 5000 mol substrate mol acid site density <-1 > h <-1 > to 50000 mol substrate mol acid site density <-1 > h <-1 >; wherein the raw material is an alkane-alkene mixture; the solid acid catalyst comprises an active component and a carrier, wherein the carrier contains at least one inorganic oxide; the active component has a structure as shown in a formula (1) and / or a formula (2), in the formula (1) and the formula (2), R is alkyl or phenyl, and n is greater than or equal to 1. According to the catalysis method provided by the invention, the conversion rate of alpha-olefin can be increased, and the proportion of skeleton isomerization products and oligomers in internal olefin products can be reduced.

A process for the manufacture of styrene acrylic copolymers having a renewably-sourced carbon content comprises the steps of: a) subjecting a feedstock comprising a renewably-sourced ethanol to dehydration to produce a renewably-sourced ethylene stream; b) subjecting at least a portion of the renewably-sourced ethylene stream to an olefin-interconversion, to obtain a renewably-sourced propylene; the olefin- interconversion comprising (i) and (ii): (i) ethylene dimerization to obtain n-butenes; (ii) metathesis reaction between n-butenes obtained according to (i) and ethylene to obtain propylene; and c) subjecting a portion of the renewably-sourced propylene to an oxidation reaction to produce acrylic acid; d) subjecting a portion of the renewably- sourced propylene to a hydroformylation reaction with syngas to produce n-butyraldehyde; e) subjecting the n-butyraldehyde to hydrogenation to produce n-butanol; f) esterifying acrylic acid obtained in step c) and the n-butanol to produce n-butyl acrylate; g) subjecting ethylene to an alkylation reaction with benzene to produce ethylbenzene; h) subjecting the ethylbenzene to a dehydrogenation reaction to produce styrene; i) copolymerizing the styrene and the n-butyl acrylate to produce a styrene acrylic copolymer. The process has a high renewably-sourced carbon content, in particular an increased renewably-sourced carbon content with respect to the renewably-sourced carbon content available in a cracker-based process.

The invention relates to the technical field of isomerization reaction catalysts, in particular to an isomerization reaction catalyst and a preparation method and application thereof.Sodium metaaluminate, silica sol, sodium hydroxide and hexamethyleneimine are added into distilled water to be stirred and mixed to obtain a reaction mixture, the reaction mixture comprises SiO2, Al2O3, NaOH, HMI and H2O, the reactant mixture is crystallized to obtain a crude product, and the crude product is dried to obtain the isomerization reaction catalyst. Carrying out suction filtration, washing and drying on the crude product to obtain molecular sieve raw powder; the molecular sieve raw powder is roasted and then is subjected to ion exchange by using an ammonium nitrate solution, the isomerization reaction catalyst is obtained after continuous roasting, a proper internal olefin raw material is obtained by using the catalyst in cooperation with isomerization condition control, and ASA synthesized by the internal olefin is excellent in paper sizing performance.

The invention discloses a catalyst for preparing mesitylene. The catalyst is prepared from the following components: 65%-80% of a molecular sieve, 15%-30% of gamma-Al2O3 and 0.25%-2.5% of a metal element. The preparation method comprises the following steps: uniformly mixing a molecular sieve and a gamma-Al2O3 precursor substance respectively, adding a peptizing agent and an extrusion aid, and kneading to obtain an initial product; carrying out extrusion forming on the initial product, drying and roasting at high temperature to obtain a catalyst body; and carrying out equivalent-volume impregnation on the catalyst body and a metal salt solution for 24-26 hours, taking out and drying, and finally roasting at high temperature to obtain the mesitylene catalyst. The prepared catalyst has acid strength and pore size suitable for isomerization of 1, 2, 4-trimethylbenzene, dealkylation reaction and disproportionation reaction are effectively inhibited, generation of xylene and tetramethylbenzene is reduced, the selectivity of isomerization reaction can reach 67%, the yield of 1, 2, 4-trimethylbenzene can reach 24.5%, and waste of raw materials is reduced.

The invention discloses an EU-1 molecular sieve and a synthesis method thereof, and belongs to the field of EU-1 molecular sieves. According to the EU-1 molecular sieve disclosed by the invention, the EU-1 molecular sieve is in a tetragonal shape; the average grain size of grains of the EU-1 molecular sieve is less than or equal to 600nm, the specific surface area SBET of the EU-1 molecular sieve is more than or equal to 390m < 2 > / g, and the micropore volume Vmicro is more than or equal to 0.22 cm < 3 > / g; the synthesis method of the EU-1 molecular sieve comprises the following steps: mixing a template agent, a silicon source, an aluminum source, an alkali source and a solvent I, aging, and carrying out segmented crystallization to obtain the EU-1 molecular sieve, according to the synthesis method of the EU-1 molecular sieve, disclosed by the invention, the EU-1 molecular sieve can be induced to form nucleated microcrystals to modulate within a very wide range by controlling crystallization time and temperature, so that a nanoscale product, namely the EU-1 molecular sieve, is obtained; in addition, the EU-1 molecular sieve crystal grain morphology can have a specific square morphology by regulating and controlling the proportion of cations in the crystallization system.

The invention provides a nickel metal hydroisomerization catalyst as well as a preparation method and application thereof. The catalyst comprises nickel, an alumina carrier and a molecular sieve, the nickel is loaded on the alumina carrier, and the content of the nickel in the catalyst is 1-10wt%; the molecular sieve is an SAPO molecular sieve. According to the invention, alumina is used as a carrier, non-noble metal nickel is loaded through a wet immersion method and is mixed with the molecular sieve to prepare the alkane isomerization catalyst, so that active metal with smaller particle size and higher dispersity can be provided, metal agglomeration at high temperature is avoided, and the utilization rate of metal is increased; the catalyst with excellent catalytic activity can be obtained only by loading low-content nickel metal, the catalyst has higher catalytic activity and selectivity, the obtained product contains more isomers, and the low-temperature fluidity of the product can be remarkably improved.

The invention relates to a straight-chain olefin skeleton isomerization method, which is characterized in that under isomerization conditions, a catalyst containing a BUCT-10 molecular sieve and straight-chain olefin are subjected to a contact reaction to realize conversion to isoolefin rich in methyl branched chains, the BUCT-10 molecular sieve has a one-dimensional ten-membered ring straight pore channel, the pore opening is in an oval shape, and the BUCT-10 molecular sieve is provided with a one-dimensional ten-membered ring straight pore channel. The characteristic size of the pore diameter is about # imgabs 0 # imgabs 1 #; and the skeleton consists of phosphorus and aluminum elements isometrically substituted by heteroatoms, and has moderate-strength Bronsted acidity. The method provided by the invention has the following remarkable advantages: (1) the initial selectivity of isoolefin is high; (2) the isoolefin yield is high; and (3) the catalyst is long in service life.

The invention relates to the technical field of linalool synthesis, in particular to a decoloring and aroma-keeping method for synthesizing linalool, which comprises the following specific steps: S1, cracking generation: heating beta-pinene to high temperature, and cracking the beta-pinene to generate myrcene; s2, rapid cooling: rapidly cooling the split product myrcene to avoid side reaction; s3, crude sample generation: in the presence of an acid catalyst, myrcene reacts with water to generate linalool, the reaction temperature is 40-80 DEG C, and the reaction time is 4-12 hours; s4, neutralizing the crude sample: after the reaction is finished, neutralizing residual acid by using a sodium bicarbonate solution, and separating an organic phase by using a separating funnel; s5, washing the crude sample: washing the organic layer to be neutral, and removing water-soluble impurities at the same time; s6, purifying the crude sample: adding anhydrous sodium sulfate to dry an organic layer. According to the decoloring and fragrance-keeping method used in the invention, the synthesized linalool is easy to decolor and natural in fragrance, can easily meet the standards of food additives and spice supplies, and has a wide application prospect.

According to the method, a heteroatom EWT structure molecular sieve with a framework containing aluminum atoms and heteroatoms is adopted as a catalyst, the molecular sieve has the advantage of improving the utilization rate of an acid center, and when the molecular sieve is used for a gas-phase non-hydroisomerization reaction of the unsym-trimethylbenzene, the utilization rate of the acid center is increased; according to the present invention, the activity, the selectivity and the stability are high, the catalytic performance is significantly improved, the mesitylene selectivity and the mesitylene yield are higher than the heteroatom-free [Si, Al]-EWT structure molecular sieve, and the by-products such as tetratoluene and xylene are significantly reduced.

The invention discloses a preparation method of a bifunctional catalyst, the bifunctional catalyst and application, the preparation method comprises the following steps: (1) soaking an acidic functional component with an organic matter solution to obtain an acidic functional component precursor; (2) carrying out pre-reduction treatment on the dehydrogenation hydrogenation functional component to obtain a pretreated dehydrogenation hydrogenation functional component; and (3) kneading, molding, drying and roasting a mixture containing the acidic functional component precursor, the pretreated dehydrogenation and hydrogenation functional component, an auxiliary agent and a binder to obtain the bifunctional catalyst. The bifunctional catalyst disclosed by the invention has the characteristics of high conversion rate, good selectivity and excellent regeneration performance.

The invention belongs to the technical field of catalyst preparation, and particularly relates to a preparation method and application of silicon-aluminum aerogel. The preparation method comprises the following steps: (1) dissolving a silicon source in an alcoholic solution, and adding an acid solution for hydrolysis to obtain a silicon solution; (2) adding an aluminum source into the silicon solution obtained in the step (1), and uniformly stirring; (3) adjusting the pH value to 4-5 by using ammonia water, gelatinizing the solution at a constant temperature of 40-120 DEG C, and aging for 12-48 hours; and (4) carrying out hydrophobic treatment on the gel obtained in the step (3), and drying and roasting the gel to obtain the SiO2-Al2O3 aerogel. The preparation process is simple and controllable, meanwhile, equipment is simple, industrial amplification is easy, olefin isomerization can be achieved, and greenhouse gas carbon dioxide can be directly converted into high-added-value isoolefin.

The present invention relates to a preparation method and application of a catalyst for catalyzing the production of mesitylene from trimethylbenzene. The method comprises the following steps: firstly preparing a multi-level pore Hβ zeolite molecular sieve, then mixing the multi-level pore Hβ zeolite molecular sieve with a hydrogen-type mordenite molecular sieve and a binder, adding a nitric acid solution and water, extruding the zeolite molecular sieve into strips, drying the strips and then calcining the strips at 500-750°C to obtain an unmodified catalyst I; performing impregnation modification on the unmodified catalyst I, then drying and calcining the strips to obtain a modified catalyst; and reducing the modified catalyst in a hydrogen atmosphere at 0.3-1MPa and 350-450°C to obtain a catalyst for isomerization of trimethylbenzene to mesitylene. The present invention utilizes a multi-level pore Hβ zeolite molecular sieve and a hydrogen-type mordenite molecular sieve to form a composite molecular sieve catalyst, then adding rare earth metals, Group VIII, Group IIIB and Group IVB as modifying elements, and reducing the catalyst with hydrogen to improve the selectivity and thermal stability of the catalyst, while increasing the life of the catalyst and improving the economic efficiency of the device.

The present invention discloses a hydroisomerization catalyst and a preparation method thereof, and a mixed C4 olefin hydroisomerization method, the hydroisomerization catalyst comprises a carrier and an active component loaded on the carrier, the carrier comprises a mixture of a carrier matrix and a modified metal, the modified metal is selected from at least one of VIB group metals, and the active component is selected from at least one of C4-C4 olefin and C4-C4 olefin. The active component comprises a metal M and / or an oxide thereof, and the metal M is selected from at least one of metal palladium, metal platinum, metal rhodium and metal ruthenium. The catalyst can catalyze the hydroisomerization conversion of butene-1 into butene-2, and has the advantages of high butene-1 conversion rate and high butene-2 selectivity.

An isomerization process includes a deisobutanizer receiving a feed comprising n-butane. The deisobutanizer delivers a portion of its bottoms to the reboiler and another portion to the isomerization reactor along with hydrogen, and the reactor effluent is returned to the column. A stabilizer is integrated with the column, the top stream is used as a reflux and the bottom contains an iso-butane rich stream, which is an iso-butane product stream. The overhead effluent is sent to a separator that separates the hydrocarbons and the effluent, where the hydrocarbons are sent to the deisobutanizer, the effluent is recycled to a stabilizer, where the stabilizer separates the reactor effluent into a product stream comprising an isobutane product stream, an n-butane product stream, and a lighter hydrocarbon product stream.

The invention belongs to the technical field of zeolite catalysts, and particularly relates to a preparation method of hierarchical pore zeolite. Through a high-silicon / pure-silicon seed crystal-selective etching synergistic strategy, in a synthesis stage, more than 30% of high-silicon (silica-alumina ratio (SAR) is greater than or equal to 500) or pure-silicon (SAR-infinity) seed crystals are introduced into a gel system, and most of the seed crystals are ensured to be embedded into a product skeleton in a complete form; in the post-treatment stage, the high-silicon seed crystal area is etched preferentially through an alkaline solution, mesopores are directionally generated, meanwhile, a matrix micropore structure is reserved, and precise customization of the hierarchical pore structure is achieved. The mesopore volume of the prepared hierarchical pore zeolite reaches 0.35 cm < 3 > / g or above, the external specific surface area is increased (180-220 m < 2 > / g vs traditionally smaller than 120 m < 2 > / g), pollution of toxic template agents is avoided, and the method is suitable for large-scale production of multiple types of zeolite such as ZSM-5 and Beta.

Disclosed in the present application are a non-noble metal-based bifunctional catalyst, a preparation method therefor, and the use thereof. The non-noble metal-based bifunctional catalyst comprises a support and an active component; the support is a hydrogen-type ZSM-48 molecular sieve; the active component comprises an active element, the active element being selected from among at least one of Fe, Co and Ni, and the dispersion of the active component being 5.5-40%. The catalyst is prepared by preparing an aluminum source, a templating agent, an inorganic base, a metal precursor and water into a mother solution, and then adding the parent ZSM-48 molecular sieve to the mother solution to be subjected to hydrothermal crystallization at a certain temperature. An one-step recrystallization policy is used to simultaneously construct metal sites and acid sites of the bifunctional catalyst. The bifunctional catalyst prepared by the method has advantages of high metal dispersion and good stability, and exhibits excellent catalytic activity and target product yields in chain alkane isomerization reactions.

The invention discloses a ZSM-48 molecular sieve with low relative crystallinity, a preparation method and application thereof, and a method for improving the performance of the ZSM-48 molecular sieve by adjusting hydrothermal synthesis time. In the synthesis stage of the ZSM-48 molecular sieve, under the condition that the composition of the synthesis liquid is not changed, the hydrothermal synthesis time is shortened, the acid sites of the molecular sieve are moderately reduced, the distribution of the acid sites of the molecular sieve is changed, and the incompletely crystallized molecular sieve is prepared. Furthermore, the ZSM-48 molecular sieve with low relative crystallinity is used as a carrier, the ZSM-48 molecular sieve loaded with noble metal platinum is used for a hydroisomerization reaction of long-chain n-alkanes, due to a proper amount of acid sites and proper distribution of the acid sites, an isoparaffin product can be prepared with high selectivity, generation of cracking products is inhibited, and the yield of the isoparaffin product is improved. And the proportion of a single-branched chain product is obviously improved.

The present invention relates to the field of catalyst technology, and discloses a hydrogen-type boron-containing EU-1 molecular sieve and a preparation method thereof, a C8 aromatic hydrocarbon isomerization catalyst and a preparation method and application thereof. The molecular sieve contains metal cations, and the metal cations are alkali metal cations with an atomic number ≮19 and / or alkaline earth metal cations with an atomic number ≮19; in the hydrogen-type boron-containing EU-1 molecular sieve, the ratio of the molar amount of the metal cations, the molar amount of silicon atoms, and the sum of the molar amounts of boron atoms and aluminum atoms is 0.05-0.7:10-100:1, and the molar ratio of the boron atoms to the aluminum atoms is 0.1-1.5:1. The C8 aromatic hydrocarbon isomerization catalyst provided by the present invention is used for catalyzing the isomerization reaction of C8 aromatic hydrocarbons, and can improve the yield of C8 aromatic hydrocarbons while maintaining a high isomerization activity.

The application provides a C8 aromatic hydrocarbon isomerization catalyst and a preparation method and application thereof. The catalyst contains an active component and a carrier; wherein, based on the weight of the carrier, the carrier contains 5wt%-25wt% of HZSM-23, 5-30wt% of mordenite, 20-60wt% of macroporous alumina and 10wt%-25wt% of a binder component. The method comprises preparation of the carrier and loading of the active metal, wherein the preparation process of the carrier is as follows: HZSM-23 molecular sieve, mordenite, macroporous alumina and a binder are mixed and formed, and the carrier is prepared after drying and calcination. The catalyst is used for C8 aromatic hydrocarbon isomerization reaction, and has the characteristics of high ethylbenzene conversion rate and high xylene yield when the xylene is at an equilibrium concentration.

The invention discloses a catalyst based on a twelve-membered ring aluminophosphate molecular sieve, a preparation method and a long-chain alkane isomerization method. The catalyst comprises the twelve-membered ring aluminophosphate molecular sieve, a noble metal active component and a metal oxide auxiliary active component. The twelve-membered ring aluminum phosphate molecule is selected from at least one of SAPO-5 (silicoaluminophosphate), MeAPO-5, SAPO-31 (silicoaluminophosphate) and MeAPO-31 (silicoaluminophosphate); the noble metal active component is selected from at least one of Pt and Pd; the metal oxide auxiliary agent is selected from at least one of SnO2 and TiO2. The preparation method comprises the following steps: loading the auxiliary agent on the twelve-membered ring aluminophosphate molecular sieve, roasting, loading the noble metal active component, roasting and reducing to obtain the target catalyst. Compared with the catalyst prepared in the prior art, the catalyst prepared by the method provided by the invention has higher activity and isomer yield in the isomerization reaction of long-chain n-alkanes.

The invention relates to a method and device for preparing low-carbon olefins, and the method comprises the following steps: S1, contacting raw oil with a catalytic conversion catalyst in a catalytic conversion reactor for catalytic conversion reaction to obtain a catalytic conversion reaction product; s2, separating the catalytic conversion reaction product to obtain ethylene and propylene as well as a first circulating olefin flow containing butene and / or a second circulating olefin flow containing C5 + olefin; s3, enabling the olefin material to enter an etherification unit, and contacting the olefin material with an alcohol raw material under an etherification condition to obtain a circulating ether material and etherified olefin; and S4, enabling at least one part of etherified olefin to enter an isomerization unit, and carrying out isomerization reaction in the presence of an isomerization catalyst to obtain isomerized olefin. According to the method disclosed by the invention, the conversion of ethers into low-carbon olefins can be realized, the yield and selectivity of ethylene and propylene are improved, the yield of methane is reduced, the content of methanol in the product is reduced to the greatest extent, and the conversion of low-cost methanol into low-carbon olefins is realized.

The invention provides a modified molecular sieve and a preparation method and application thereof, the modified molecular sieve is a Na-type molecular sieve containing Mg element, and preferably, the modified molecular sieve also contains a template agent. When the molecular sieve is used for preparing trans-m-pentadiene, the reaction temperature is low, the product yield is high, the operation is simple, and the recovery is convenient; according to the preparation method provided by the invention, an Mg source is added in the process of synthesizing the molecular sieve, and the modified molecular sieve product can be prepared without roasting after crystallization.

This application discloses a method for preparing n-butene from isobutene, comprising the following steps: contacting a raw material containing isobutene with a catalyst and reacting to obtain a product containing n-butene; the catalyst is composed of MgAl2O4 and a hierarchical porous molecular sieve; and obtaining the catalyst through the following steps: 1) subjecting the molecular sieve to alkali treatment and acid treatment in sequence to obtain the porous molecular sieve; 2) wet mixing of magnesium source and aluminum source and calcining to obtain the MgAl2O4; 3) mixing the porous molecular sieve with the MgAl2O4 and calcining to obtain the catalyst.