Method for selective hydrogenation of trace amounts of acetylene in methanol to olefins

Abstract

The application discloses a method for removing acetylene by selective hydrogenation in methanol-to-olefin, which uses a hydrogenation catalyst to selectively hydrogenate and refine methanol-to-ethylene products, and the hydrogenation object is trace acetylene contained in the overhead effluent after the methanol-to-ethylene products are subjected to alkali washing, drying, demethanization and deethanization, and the raw material composition is mainly as follows: ethylene >=99.9%(Φ), acetylene 5-100ppm, CO 1-10ppm. The catalyst carrier is alumina or mainly alumina and has a bimodal pore distribution structure, and the catalyst contains at least Fe, Pd, Ni and Cu, wherein Fe is loaded in a solution mode, Ni and Cu are loaded in a microemulsion mode, and Pd is loaded in both a microemulsion mode and a solution mode; the solution-loaded Fe and Pd are mainly loaded in small pores, and the microemulsion-loaded Ni, Cu and Pd are mainly distributed in large pores of the carrier. The catalyst used in the method has low Pd content, low 'green oil' generation, and excellent catalytic performance and anti-coking performance.

Description

Technical Field

[0001] This invention relates to a method for selective hydrogenation of trace amounts of acetylene in methanol-to-olefins production, and more particularly to a method for selective hydrogenation of trace amounts of acetylene in the products of methanol-to-ethylene production using a Fe-Pd-Ni-Cu hydrogenation catalyst. Background Technology

[0002] Ethylene, propylene, and other low-carbon olefins are important basic chemical raw materials. With the development of my country's national economy, especially the development of modern chemical industry, the demand for low-carbon olefins is increasing, and the supply-demand imbalance is becoming increasingly prominent. To date, the main route for producing ethylene, propylene, and other low-carbon olefins is still through the catalytic cracking and pyrolysis of naphtha and light diesel oil (both derived from petroleum). However, the raw material resources such as naphtha and light diesel oil used in ethylene production are facing increasingly severe shortages. Furthermore, in recent years, my country's crude oil imports have accounted for about half of its total processing volume, and the import ratio of polyolefin products using ethylene and propylene as raw materials will continue to remain quite high. Therefore, the development of technologies for producing low-carbon olefins from non-petroleum resources is attracting increasing attention.

[0003] The MTO (methanol-to-ethylene) and MTP (methanol-to-propylene) processes are important chemical technologies. These technologies use methanol synthesized from coal or natural gas as feedstock to produce low-carbon olefins and are core technologies for developing the production of ethylene, propylene, and other products from non-petroleum resources.

[0004] Methanol-to-olefins (MTO) is a key step in the coal-to-olefins industry chain. Its process mainly involves using methanol as a feedstock and selecting a suitable catalyst under appropriate operating conditions in fixed-bed or fluidized-bed reactors to produce low-carbon olefins through methanol dehydration. Depending on the target product, MTO processes are categorized as methanol-to-ethylene, methanol-to-propylene, and methanol-to-propylene. The entire MTO reaction can be divided into two stages: a dehydration stage and a cracking reaction stage.

[0005] 1. Dehydration stage

[0006] 2CH3OH→CH3OCH3+H2O+Q

[0007] 2. Pyrolysis reaction stage

[0008] The reaction process mainly involves the catalytic cracking of dimethyl ether, the dehydration product, and a small amount of unconverted methanol, including:

[0009] Main reaction (forming an olefin):

[0010] nCH3OH→C n H 2n +nH2O+Q

[0011] nCH3OH→2C n H2n +nH2O+Q

[0012] n = 2 and 3 (primary), 4, 5 and 6 (minor)

[0013] All of the above olefin products are in the gaseous state.

[0014] Side reactions (forming alkanes, aromatics, carbon oxides, and coking):

[0015] (n+1)CH3OH→C n H 2n+2 +C+(n+1)H2O+Q

[0016] (2n+1)CH3OH→2C n H 2n+2 +CO + 2nH2O + Q

[0017] (3n+1)CH3OH→3C n H 2n+2 +CO2+(3n-1)H2O+Q

[0018] n=1, 2, 3, 4, 5…………

[0019] nCH3OCH3→C n H 2n-6 +3H2+nH2O+Q

[0020] n = 6, 7, 8...

[0021] After methanol undergoes dehydration, cracking, and separation, the ethylene feed at the top of the de-ethaner tower still contains 5–100 ppm of acetylene. This acetylene affects the ethylene polymerization process and causes a decline in product quality, necessitating its removal through selective hydrogenation. The selective hydrogenation of trace amounts of acetylene in the ethylene feed has a crucial impact on the ethylene polymerization process. Besides ensuring sufficient activity in the hydrogenation process to achieve good acetylene removal performance under low acetylene content conditions, guaranteeing that both the acetylene and hydrogen content at the reactor outlet meet standards, excellent catalyst selectivity is also required to minimize the formation of ethane from ethylene, ensuring that the hydrogenation process does not result in any loss of ethylene in the unit.

[0022] Currently, selective hydrogenation of trace amounts of acetylene in ethylene feedstock of methanol-to-olefins (MTO) plants mainly employs a single-stage reactor process. The reactor inlet feedstock composition is: ethylene ≥ 99.99% (Φ), acetylene 5–100 ppm, CO 1–10 ppm, and hydrogen is mixed with an H2 / C2H2 ratio of 2–6. The reaction pressure is 1.5–2.5 MPa, and the space velocity is 2000–10000 h⁻¹. -1 The inlet temperature is 25℃~60℃.

[0023] Selective hydrogenation catalysts for alkynes and dienes are obtained by supporting noble metals such as palladium on porous inorganic material supports (US4762956). To increase catalyst selectivity and reduce catalyst deactivation caused by green oil produced during oligomerization reactions during hydrogenation, existing technologies employ methods such as adding Group IB elements as co-catalytic components: Pd-Au (US4490481), Pd-Ag (US4404124), Pd-Cu (US3912789), or adding alkali metals or alkaline earth metals (US5488024), etc. Supports used include alumina, silica (US5856262), and honeycomb lapis lazuli (CN1176291). Patent US4404124 describes a selective hydrogenation catalyst with a palladium shell layer distribution of the active component prepared by a stepwise impregnation method. This catalyst can be applied to the selective hydrogenation of C2 and C3 fractions to eliminate acetylene from ethylene and propyne and propadiene from propylene. US5587348 describes a high-performance C2 hydrogenation catalyst prepared by using alumina as a support, adjusting the interaction between silver and palladium co-catalysts, and adding alkali metals and chemically bonded fluorine. This catalyst features reduced green oil formation, improved ethylene selectivity, and reduced oxygen-containing compound formation. US5519566 discloses a wet reduction method for preparing silver and palladium catalysts by adding organic or inorganic reducing agents to the impregnation solution to prepare a silver and palladium bicomponent selective hydrogenation catalyst. CN105732266A discloses a Pd-Ag catalyst using Al2O3 or a mixture of Al2O3 and other oxides as a support. The catalyst contains 0.025–0.060% Pd and 0.05–0.4% Ag by mass (100%). Patents such as CN102898266A, CN107970927A, CN105732266A, and CN105732271A all utilize Pd catalysts.

[0024] The above-mentioned traditional C2 hydrogenation catalysts are all prepared by impregnation method, and their active phase is a Pd / Ag bimetallic catalyst. This method has the following disadvantages: (1) Due to the influence of the pore structure of the support, the dispersion of the active components cannot be precisely controlled and has strong randomness. (2) Due to the influence of the surface tension and solvation effect of the impregnation liquid, the precursor of the metal active component is deposited on the surface of the support in the form of aggregates and cannot form a uniform distribution. (3) C2 hydrogenation requires high catalyst selectivity. The traditional preparation method promotes the role of Ag promoter by increasing the amount of Ag, which leads to the obstruction of hydrogen transfer, the increased possibility of oligomerization reaction, and the increase of green oil generation, which affects the catalyst life. The occurrence of the above three phenomena easily leads to poor dispersion of metal active components, low reaction selectivity, and high green oil generation, which in turn affects the overall performance of the catalyst. (4) The Pd content in the catalyst is high, and the catalyst price is expensive. In addition, the occurrence of the above four phenomena easily leads to poor dispersion of metal active components, low reaction selectivity, and high green oil generation, which in turn affects the overall performance of the catalyst.

[0025] CN201110086174.0 describes a method that adsorbs specific polymeric compounds onto a support, forming a polymeric coating of a certain thickness on the support surface. The reaction of functionalized compounds with the polymer imparts functional groups that can complex with the active component. The active component undergoes a complexation reaction on these functional groups on the support surface, ensuring the ordered and highly dispersed nature of the active component. However, this patented method involves adsorbing specific polymeric compounds onto the support, with the polymer undergoing chemical adsorption via the hydroxyl groups of alumina. The amount of polymeric compound adsorbed by the support is limited by the number of hydroxyl groups in the alumina. Furthermore, the complexation between the functionalized polymer and Pd is weak, sometimes resulting in insufficient loading of the active component, leaving some active component residue in the impregnation solution, thus increasing catalyst costs.

[0026] To improve the anti-coking performance of catalysts and reduce the degree of surface coking, C2 selective hydrogenation catalysts and their preparation methods using bimodal porous supports and microemulsion methods for loading active components have been disclosed in recent years. Patent ZL201310114077.7 discloses a selective hydrogenation catalyst whose support is mainly alumina with a bimodal porous structure, wherein the pore size is less than 50 nm and the macropore size is 60–800 nm. Based on 100% catalyst mass, the catalyst contains 0.01–0.5% Pd in ​​a shell distribution with a thickness of 1–500 μm; and 0.2–5% Ni. The anti-coking component Ni is controlled by microemulsion method, where the microemulsion particle size is larger than the support pore size, so that Ni is mainly distributed in the macropores of the support. Patent ZL201310114079.6 discloses a method for preparing a hydrogenation catalyst, where the catalyst support is mainly alumina with a bimodal porous structure. The catalyst contains two active components, Pd and Ni. During catalyst preparation, the anti-coking component Ni is introduced into the macropores of the support in the form of a microemulsion, while the active component Pd is mainly distributed on the support surface, particularly in the micropores. Patent ZL201310114371.8 discloses a selective hydrogenation method for C2 fractions suitable for pre-propane dehydrogenation processes. This method uses a selective hydrogenation catalyst whose support is alumina or mainly alumina, with a bimodal pore distribution structure, containing two active components, Pd and Ni, with the anti-coking component Ni mainly distributed in the macropores. While this method improves the catalyst's anti-coking performance, the single-component Ni in the macropores of the catalyst support reaches reduction temperatures above 500°C. Reduction at this temperature causes the active component Pd to aggregate, significantly reducing catalyst activity. To compensate for the loss of catalyst activity, the amount of active component needs to be increased, leading to a decrease in catalyst selectivity and a reduction in the utilization rate of the active component.

[0027] CN106927993A discloses a catalyst active component containing at least Fe and Cu. It is believed that adding Cu to the iron-containing active component is more conducive to lowering the activation temperature, promoting the formation and dispersion of the activated phase, and improving catalyst selectivity. Simultaneously, the addition of Cu facilitates the adsorption and activation of alkynes, further enhancing catalyst activity. The calcination temperature is preferably 300℃~400℃; reduction is carried out at 260~330℃.

[0028] In addition, we have developed a series of Fe-based bimetallic acetylene selective hydrogenation and acetylene removal catalysts. Taking the typical CN106928001.B as an example, the acetylene hydrogenation method disclosed in the catalyst contains at least Fe and Cu as active components. Based on 100% catalyst mass, the catalyst contains 1-8% Fe and 0.03-0.3% Cu, with a catalyst specific gravity of 10-200 mg / L. 2 / g, with a pore volume of 0.2–0.63 mL / g. Summary of the Invention

[0029] This invention relates to a method for selective hydrogenation of trace amounts of acetylene in methanol-to-olefins production, and more particularly to a method for selective hydrogenation of trace amounts of acetylene in the products of methanol-to-ethylene production using a Fe-Pd-Ni-Cu hydrogenation catalyst.

[0030] This invention provides a method for selective hydrogenation of trace amounts of acetylene in methanol-to-olefins production, the method comprising:

[0031] A hydrogenation catalyst was used to selectively hydrogenate and purify the methanol-to-ethylene product. The target of hydrogenation was trace amounts of acetylene contained in the overhead effluent of the methanol-to-ethylene product after alkaline washing, drying, demethanization, and deethane removal. The inlet temperature of the hydrogenation reactor was 25℃–90℃, the reaction pressure was 1.5–3.5 MPa, and the space velocity was 2000–10000 h⁻¹. -1 The H2 / C2H2 ratio is 1–20; the catalyst support is alumina or mainly alumina, and has a bimodal pore distribution structure; the catalyst contains at least Fe, Pd, Ni, and Cu, wherein Fe is supported in solution, Ni and Cu are supported in microemulsion, and Pd is supported in both microemulsion and solution. Based on 100% of the catalyst mass, the Fe content is 0.5–1.5%, the Pd content is 0.007–0.01%, the Ni content is 0.9–7.5%, the weight ratio of Cu to Ni is 0.15–0.90, and the Pd content in the microemulsion-supported catalyst is 1 / 300–1 / 500 of the Cu content; wherein, the Ni, Cu, and Pd supported in the microemulsion are mainly distributed in the macropores of the support.

[0032] The selective hydrogenation method described in this invention refers to the selective hydrogenation of trace amounts of acetylene contained in a material into ethylene in a single-stage adiabatic bed reactor.

[0033] This invention provides a selective hydrogenation method for trace amounts of acetylene in methanol-to-olefins (MTO) reactors. The product of methanol-to-ethylene production is fed into a single-stage adiabatic reactor for selective hydrogenation to remove acetylene and convert it into ethylene. The feedstock composition is primarily: ethylene ≥ 99.9% (Φ), acetylene 5–100 ppm, and CO 1–10 ppm. The reaction conditions are: reactor inlet temperature 25℃–90℃, reaction pressure 1.5–3.5 MPa, and space velocity 2000–10000 h⁻¹. -1 The H2 / C2H2 ratio is 1–20; the preferred reaction conditions are: reactor inlet temperature 30℃–60℃, reaction pressure 2.0–3.0 MPa, and space velocity 6000–9000 h⁻¹. -1 The H2 / C2H2 ratio is 2 to 5.

[0034] The selective hydrogenation method of the present invention uses a catalyst containing at least Fe, Pd, Ni, and Cu. Fe is supported in solution, Ni and Cu are supported in microemulsion, and Pd is supported in both microemulsion and solution. Based on 100% of the catalyst mass, the Fe content is 0.5–1.5%, preferably 0.55–1.3%; the Pd content is 0.007–0.01%, preferably 0.008–0.009%; the Ni content is 0.9–7.5%, preferably 3.0–6.8%; the weight ratio of Cu to Ni is 0.15–0.90, preferably 0.2–0.7; and the Pd content in the microemulsion-supported catalyst is 1 / 300–1 / 500 of the Cu content, preferably 1 / 400–1 / 450. The Ni, Cu, and Pd supported in the microemulsion are mainly distributed in the macropores of the support at a wavelength of 680–950 nm.

[0035] The selective hydrogenation method of this invention uses a hydrogenation catalyst supported on alumina or primarily alumina, exhibiting a bimodal pore distribution structure. The micropores have a diameter of 50–80 nm, and the macropores have a diameter of 680–950 nm. The Al₂O₃ support is preferably in α, θ, or a mixture thereof. The alumina content in the support is above 80 wt%, and the support may also contain at least one of magnesium oxide and titanium oxide. The specific surface area of ​​the catalyst is 1–7 m². 2 / g.

[0036] The selective hydrogenation method of the present invention uses a hydrogenation catalyst containing at least Fe, Pd, Ni, and Cu. The selective hydrogenation reaction of alkynes occurs at reaction centers composed of Fe and Pd. Fe, with a content of 0.5-1.5%, is the main active component of the catalyst, and its role is to adsorb and activate acetylene, thereby catalyzing the selective hydrogenation of acetylene. A small amount of Pd, with a solution loading content of 0.007-0.01%, is a co-active component of the catalyst, which facilitates the rapid dissociation of hydrogen and thus improves the activity of the catalyst.

[0037] In the selective hydrogenation method described in this invention, Ni and Cu in the hydrogenation catalyst are impregnated in the macropores of the support in the form of a microemulsion, and the green oil generated in the reaction undergoes saturated hydrogenation on the active centers composed of Cu and Ni.

[0038] In the selective hydrogenation method described in this invention, the role of Cu in the hydrogenation catalyst is to form a Ni / Cu alloy during the calcination process, effectively reduce the reduction temperature of nickel during the reduction process, reduce the polymerization of Fe and Pd at high temperatures, improve the dispersion of the main active components, and simultaneously modulate the saturated hydrogenation reaction performance of Ni in macropores.

[0039] For the hydrogenation reaction of acetylene, the side reaction that produces large molecules is the main reason for the covering of active components, further leading to a decrease in catalyst activity. The solution to catalyst coking in this invention is as follows:

[0040] Selective hydrogenation of alkynes occurs at the main reaction centers of the catalyst, such as Fe and Pd. Large molecules like the green oil produced in the reaction easily enter the macropores of the catalyst. Within these macropores, a Ni / Cu component is loaded, where Ni possesses saturated hydrogenation capabilities. The green oil component undergoes saturated hydrogenation at the active centers of the Ni / Cu composition. Because the double bonds are hydrogenated and saturated, the green oil component cannot undergo polymerization or its polymerization rate is significantly reduced. Its chain growth reaction is terminated or delayed, preventing the formation of large molecular weight fused-ring compounds. This prevents the green oil component from being carried out of the reactor by the surrounding material, thus greatly reducing coking on the catalyst surface and significantly extending its service life.

[0041] The selective hydrogenation method described in this invention uses Fe as the main active component. However, compared with the disclosed iron-based acetylene hydrogenation catalysts, the Fe content is lower, even below 1%, and the reduction temperature is also significantly reduced, allowing the catalyst to be reduced below 200°C.

[0042] In the selective hydrogenation method described in this invention, Pd loaded in solution is used as a co-activating component to increase the activity of the catalyst and modulate the selectivity of the catalyst. Compared with the disclosed noble metal Pd-based acetylene hydrogenation catalysts, the Pd content is significantly reduced, even by more than 50%.

[0043] The method for controlling the positioning of the Ni / Cu alloy within the macropores of the catalyst in this invention involves loading Ni / Cu in the form of a microemulsion. The particle size of the microemulsion is larger than the micropore diameter of the support but smaller than the maximum pore diameter of the macropores. The nickel and copper metal salts, contained within the microemulsion, have difficulty entering the smaller pores of the support due to steric hindrance, and therefore primarily enter the macropores of the support.

[0044] In this invention, loading Cu and Ni together can lower the reduction temperature of Ni. This is because to completely reduce NiO alone, a reduction temperature of 450-500°C is generally required. At this temperature, Pd will agglomerate. However, after forming a Cu / Ni alloy, its reduction temperature can be reduced by more than 100°C compared to the reduction temperature of pure Ni, reaching 350°C, thereby alleviating the agglomeration of Fe and Pd during the reduction process.

[0045] In this invention, a small amount of Pd loaded in a microemulsion on the surface of the Ni / Cu alloy can further reduce the reduction temperature of Ni to below 200°C, with a minimum of 150°C.

[0046] In this invention, during the process of loading Fe using the solution method, the solution containing Fe enters the pores more quickly due to the siphon effect of the pores. Since Fe exists in the form of ions, it can form chemical bonds with the hydroxyl groups on the surface of the support, thereby being rapidly targeted. Therefore, the faster the solution enters the pores, the faster the loading speed. Thus, it is easier to load Fe into the pores during the process of impregnating Fe using the solution method.

[0047] This invention is not particularly limited to loading Ni, Cu, and Pd using a microemulsion method. As long as a microemulsion particle size greater than 80 nm and less than 950 nm can be formed, Ni, Cu, and Pd can be distributed within the macropores of the support. Preferably, the microemulsion loading process includes: dissolving a precursor salt in water, adding an oil phase, a surfactant, and a co-surfactant, and thoroughly stirring to form a microemulsion. The oil phase is an alkane or cycloalkanes, the surfactant is an ionic surfactant and / or a nonionic surfactant, and the co-surfactant is an organic alcohol.

[0048] In the hydrogenation method of this invention, the order of Fe solution loading and Ni / Cu microemulsion loading is not limited. Fe solution loading can be performed before or after Ni / Cu microemulsion loading. The Pd microemulsion loading step is performed after the Ni and Cu microemulsion loading steps, and the Pd solution loading step is performed after the Fe solution loading step.

[0049] The selective hydrogenation method of the present invention specifically includes the following steps in the catalyst preparation process:

[0050] (1) The loading of Fe was carried out by saturated impregnation. The Fe salt solution was prepared at 80-110% of the saturated water absorption rate of the support. After loading Fe, it was dried at 100-120℃ for 1-4 hours and calcined at 500-550℃ for 4-6 hours to obtain semi-finished catalyst A.

[0051] (2) Dissolve the precursor salt of Pd in ​​water, adjust the pH to 1.5-2.5, add the semi-finished catalyst A into the salt solution of Pd, impregnate and adsorb for 0.5-4 hours, dry at 100-120℃ for 1-4 hours, and calcine at 400-550℃ for 2-6 hours to obtain the semi-finished catalyst B.

[0052] (3) Dissolve the precursor salts of Ni and Cu in water, add oil phase, surfactant and co-surfactant. The weight ratio of surfactant to co-surfactant is 1.0 to 1.2, the weight ratio of water phase to oil phase is 4.8 to 6.8, and the weight ratio of surfactant to oil phase is 0.08 to 0.30. Stir thoroughly to form a microemulsion, and control the microemulsion particle size to be greater than 80 nm and less than 950 nm. Add the semi-finished catalyst B to the prepared microemulsion and impregnate for 0.5 to 4 hours. Filter out the residual liquid, dry at 60 to 120 °C for 1 to 6 hours, and calcine at 300 to 600 °C for 2 to 8 hours to obtain the semi-finished catalyst C.

[0053] (4) Dissolve the Pd precursor salt in water, add oil phase, surfactant and co-surfactant. The weight ratio of surfactant to co-surfactant is 1.0 to 1.2, the weight ratio of water phase to oil phase is 4.8 to 6.8, and the weight ratio of surfactant to oil phase is 0.08 to 0.30. Stir thoroughly to form a microemulsion, and control the microemulsion particle size to be greater than 80 nm and less than 950 nm. Add the semi-finished catalyst C to the prepared microemulsion and impregnate for 0.5 to 4 hours. Filter out the residual liquid, dry at 60 to 120 °C for 1 to 6 hours, and calcine at 300 to 600 °C for 2 to 8 hours to obtain the desired catalyst.

[0054] Alternatively, the catalyst preparation process may specifically include the following steps:

[0055] (1) The loading of Fe is carried out by saturated impregnation method, that is, the Fe salt solution is 80-110% of the saturated water absorption rate of the support. After loading Fe, it is dried at 100-120℃ for 1-4 hours and calcined at 500-550℃ for 4-6 hours to obtain semi-finished catalyst A.

[0056] (2) Ni and Cu precursor salts are dissolved in water, and an oil phase, surfactant, and co-surfactant are added. The mixture is stirred thoroughly to form a microemulsion. The microemulsion particle size is controlled to be greater than 80 nm and less than 950 nm. The conditions for preparing the microemulsion provided in this invention are: adding an oil phase, surfactant, and co-surfactant, with a surfactant-to-co-surfactant weight ratio of 1.0-1.2, an aqueous phase-to-oil phase weight ratio of 4.8-6.8, and a surfactant-to-oil phase weight ratio of 0.08-0.30. The semi-finished catalyst A is added to the prepared microemulsion and impregnated for 0.5-4 hours, and the remaining liquid is filtered off. The mixture is dried at 60-120°C for 1-6 hours and calcined at 300-600°C for 2-8 hours to obtain the semi-finished catalyst B.

[0057] (3) Dissolve the precursor salt of Pd in ​​water, adjust the pH to 1.5-2.5, add the semi-finished catalyst B to the salt solution of Pd, impregnate and adsorb for 0.5-4h, dry at 100-120℃ for 1-4h, calcine at 400-550℃ for 2-6h, and reduce with hydrogen at 350-500℃ for 3-6h to obtain the semi-finished catalyst C.

[0058] (4) Dissolve the Pd precursor salt in water, add the oil phase, surfactant, and co-surfactant, and stir thoroughly to form a microemulsion. Control the microemulsion particle size to be greater than 80 nm and less than 950 nm. The conditions for preparing the microemulsion provided in this invention are: add the oil phase, surfactant, and co-surfactant, with a weight ratio of surfactant to co-surfactant of 1.0 to 1.2, a weight ratio of aqueous phase to oil phase of 4.8 to 6.8, and a weight ratio of surfactant to oil phase of 0.08 to 0.30. Add the semi-finished catalyst C to the prepared microemulsion and impregnate for 0.5 to 4 hours, filter out the residual liquid, dry at 60 to 120°C for 1 to 6 hours, and calcine at 300 to 600°C for 2 to 8 hours to obtain the desired catalyst.

[0059] In the above preparation steps, steps (1) and (2) can be interchanged, step (3) is after step (1), and step (4) is after step (2).

[0060] The support in step (1) above is alumina or mainly alumina, and the Al2O3 crystal form is preferably α, θ or a mixture thereof. The alumina content in the catalyst support is preferably above 80%, and the support may also contain other metal oxides such as magnesium oxide, titanium oxide, etc.

[0061] The carrier in step (1) above can be spherical, cylindrical, clover-shaped, four-leaf clover-shaped, etc.

[0062] The precursor salts of Fe, Pd, Ni, and Cu mentioned in the above steps are soluble salts, which can be their nitrates, chlorides, or other soluble salts.

[0063] The surfactants in steps (2) and (4) above are ionic surfactants and / or nonionic surfactants, preferably nonionic surfactants, and more preferably polyethylene glycol octylphenyl ether (Triton X-100) or hexadecyltrimethylammonium bromide (CTAB).

[0064] The oil phase in steps (2) and (4) above is a C6-C8 saturated alkane or cycloalkane, preferably cyclohexane or n-hexane.

[0065] The co-surfactants in steps (2) and (4) above are C4 to C6 alcohols, preferably n-butanol and / or n-pentanol.

[0066] The reduction temperature of the catalyst of the present invention is preferably 150-200℃.

[0067] The method of this invention significantly reduces the amount of palladium used, even by more than 50%. The catalyst used in this method has the following characteristics: at the beginning of the hydrogenation reaction, due to the high hydrogenation activity of Fe-Pd and its predominantly distributed distribution in the micropores, the selective hydrogenation of acetylene mainly occurs in the micropores. As the catalyst's operating time increases, a portion of larger molecular weight byproducts are generated on the catalyst surface. These substances, due to their larger molecular size, enter the macropores in greater quantities and have a longer residence time. Under the action of the nickel catalyst, they undergo double bond hydrogenation reactions to generate saturated hydrocarbons or aromatic hydrocarbons without isolated double bonds, without generating substances with even larger molecular weights.

[0068] Using the selective hydrogenation method of the present invention, even if the conditions in the feedstock change and the amount of green oil generated by the catalyst increases significantly, the catalyst activity and selectivity do not show a downward trend. Attached Figure Description

[0069] Figure 1 This is a flow chart of the C2 hydrogenation process for methanol-to-ethylene using a sequential separation process.

[0070] In the attached figures, the following labels are used:

[0071] 1—Reactor, 2—Regenerator, 3—Separator, 4—Alkali washing tower, 5—Drying tower, 6—Methanation tower, 7—Ethylene removal tower, 8—Ethylene separation tower, 9—Propylene separation tower, 10—Propane removal tower, 11—Ethylene refining reactor. Detailed Implementation

[0072] Analysis and testing methods:

[0073] Comparison table: GB / T-5816;

[0074] Hole capacity: GB / T-5816;

[0075] Content of active component in catalyst: atomic absorption spectrometry;

[0076] Microemulsion particle size distribution of Ni / Cu alloy: Dynamic light scattering particle size analyzer, analyzed on M286572 dynamic light scattering analyzer;

[0077] In this embodiment, the conversion rate and selectivity are calculated using the following formula:

[0078] MAPD conversion rate (%) = 100 × ΔMAPD / inlet MAPD content

[0079] Propylene selectivity (%) = 100 × Δpropylene / ΔMAPD

[0080] Example 1

[0081] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. 100 g of the carrier was calcined at high temperature for 4 hours. The calcination temperature and carrier properties are shown in Table 1.

[0082] Catalyst preparation:

[0083] (1) Weigh out nickel nitrate and copper chloride and dissolve them in deionized water. Add cyclohexane, Triton X-100 and n-butanol and stir thoroughly to form a microemulsion. Impregnate 100g of the carrier into the prepared microemulsion. After impregnation for 1 hour, wash with deionized water until neutral. Dry at 120°C for 2 hours and calcine at 550°C for 5 hours to obtain semi-finished catalyst A.

[0084] (2) Weigh ferric chloride and prepare a solution with deionized water. Immerse catalyst A in the solution and shake. After the solution is completely absorbed, dry at 110°C for 3 hours and calcine at 500°C for 4 hours to obtain semi-finished catalyst B.

[0085] (3) Weigh palladium nitrate, dissolve it in deionized water, adjust the pH to 1, add the semi-finished catalyst B to the solution, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 400℃ for 6 hours to obtain the semi-finished catalyst C.

[0086] (4) Weigh palladium nitrate and dissolve it in water. Add cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst C to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours to obtain the finished catalyst.

[0087] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 2.

[0088] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 200°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0089] Example 2

[0090] Carrier: A commercially available bimodal spherical carrier with a diameter of 4 mm was used, consisting of 90% alumina and 10% titanium oxide. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed. The physical properties of the carrier are shown in Table 1.

[0091] Catalyst preparation:

[0092] (1) Weigh out nickel nitrate and copper chloride, dissolve them in deionized water, add cyclohexane, Triton X-100, and n-hexanol, and stir thoroughly to form a microemulsion. Add the support to the prepared microemulsion and impregnate for 1 hour, then wash with deionized water until neutral, dry at 120°C for 2 hours, and calcine at 550°C for 5 hours to obtain semi-finished catalyst A.

[0093] (2) Weigh palladium nitrate and dissolve it in water. Add cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst A to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours to obtain the semi-finished catalyst B.

[0094] (3) Weigh out ferric nitrate and dissolve it in deionized water. Immerse the semi-finished catalyst B in the prepared solution, dry it at 110°C for 3 hours, and calcine it at 500°C for 4 hours to obtain the semi-finished catalyst C.

[0095] (4) Weigh palladium nitrate salt and dissolve it in water, adjust the pH to 2, add the semi-finished product C to the salt solution of Pd, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 450℃ for 6 hours to obtain the finished catalyst.

[0096] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 2.

[0097] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 180°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0098] Example 3

[0099] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 1.

[0100] Catalyst preparation:

[0101] (1) Weigh out ferric nitrate and dissolve it in deionized water. Immerse the carrier in the prepared solution, dry it at 100°C for 3 hours, and calcine it at 500°C for 4 hours to obtain semi-finished catalyst A.

[0102] (2) Weigh palladium nitrate salt and dissolve it in water, adjust the pH to 2, add the semi-finished catalyst A into the salt solution of Pd, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 500℃ for 6 hours to obtain the semi-finished catalyst B.

[0103] (3) Weigh out nickel nitrate and copper chloride, dissolve them in water, add cyclohexane, Triton X-100, and 6.03 g of n-hexanol, and stir thoroughly to form a microemulsion. Add the semi-finished catalyst C to the prepared microemulsion and impregnate for 4 hours. Then wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours to obtain the semi-finished catalyst D.

[0104] (4) Weigh palladium nitrate and dissolve it in water. Add cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst D to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. The finished catalyst is obtained.

[0105] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 2.

[0106] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 150°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0107] Example 4

[0108] The catalyst composition and preparation steps are the same as in Example 3, and the evaluation of the raw material composition is shown in Table 3.

[0109] Example 5

[0110] The catalyst composition and preparation steps are the same as in Example 3, and the evaluation of the raw material composition is shown in Table 3.

[0111] Example 6

[0112] The catalyst composition and preparation steps are the same as in Example 3, and the evaluation of the raw material composition is shown in Table 3.

[0113] Example 7

[0114] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 1.

[0115] Catalyst preparation:

[0116] (1) Weigh out nickel nitrate and copper chloride, dissolve them in water, add cyclohexane, Triton X-100, and 6.03 g of n-hexanol, and stir thoroughly to form a microemulsion. Add the carrier to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours to obtain semi-finished catalyst A.

[0117] (2) Weigh out ferric nitrate and dissolve it in deionized water. Immerse the semi-finished catalyst B in the prepared solution, dry it at 110°C for 3 hours, and calcine it at 500°C for 4 hours to obtain the semi-finished catalyst B.

[0118] (3) Weigh palladium nitrate salt and dissolve it in water, adjust the pH to 2, add the semi-finished catalyst B to the salt solution of Pd, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 550℃ for 6 hours to obtain the semi-finished catalyst C.

[0119] (4) Weigh palladium nitrate and dissolve it in water. Add cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst C to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. The finished catalyst is obtained.

[0120] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 2.

[0121] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 170°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0122] Example 8

[0123] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 1.

[0124] Catalyst preparation:

[0125] (1) Weigh out nickel nitrate and copper chloride, dissolve them in water, add cyclohexane, Triton X-100, and 6.03 g of n-hexanol, and stir thoroughly to form a microemulsion. Add the support to the prepared microemulsion and impregnate for 4 hours, then wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. Semi-finished catalyst A is obtained.

[0126] (2) Weigh palladium nitrate and dissolve it in water. Add cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst A to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours to obtain the semi-finished catalyst B.

[0127] (3) Weigh out ferric nitrate and dissolve it in deionized water. Immerse the semi-finished catalyst B in the prepared solution, dry it at 110°C for 3 hours, and calcine it at 500°C for 4 hours to obtain the semi-finished catalyst C.

[0128] (4) Weigh palladium nitrate salt and dissolve it in water, adjust the pH to 2, add the semi-finished catalyst B to the salt solution of Pd, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 410℃ for 6 hours to obtain the finished catalyst.

[0129] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 2.

[0130] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 200°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0131] Comparative Example 1-1

[0132] Comparative Example 1-1 differs from Example 1 in that it does not have the microemulsion Pd loaded.

[0133] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. 100 g of the carrier was calcined at high temperature for 4 hours. The calcination temperature and carrier properties are shown in Table 1.

[0134] Catalyst preparation:

[0135] (1) Weigh out nickel nitrate and copper chloride and dissolve them in deionized water. Add cyclohexane, Triton X-100 and n-butanol and stir thoroughly to form a microemulsion. Impregnate 100g of the carrier into the prepared microemulsion. After impregnation for 1 hour, wash with deionized water until neutral. Dry at 120°C for 2 hours and calcine at 550°C for 5 hours to obtain the semi-finished catalyst A1.

[0136] (2) Weigh ferric chloride and prepare a solution with deionized water. Add the semi-finished catalyst A1 to the solution, shake, and after the solution is completely absorbed, dry at 110°C for 3 hours and calcine at 500°C for 4 hours to obtain the semi-finished catalyst B1.

[0137] (3) Weigh palladium nitrate, dissolve it in deionized water, adjust the pH to 1, then immerse the semi-finished catalyst B1 in the prepared Pd salt solution, immerse and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 400℃ for 6 hours to obtain the finished catalyst.

[0138] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 2.

[0139] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 200°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0140] Comparative Examples 1-2

[0141] The difference between Comparative Examples 1 and 2 and Example 1 is that there was no microemulsion Pd loading, and the catalyst reduction temperature was 450°C.

[0142] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. 100 g of the carrier was calcined at high temperature for 4 hours. The calcination temperature and carrier properties are shown in Table 1.

[0143] Catalyst preparation:

[0144] (1) Weigh out nickel nitrate and copper chloride and dissolve them in deionized water. Add cyclohexane, Triton X-100 and n-butanol and stir thoroughly to form a microemulsion. Impregnate 100g of the carrier into the prepared microemulsion. After impregnation for 1 hour, wash with deionized water until neutral. Dry at 120°C for 2 hours and calcine at 550°C for 5 hours to obtain the semi-finished catalyst A1.

[0145] (2) Weigh ferric chloride and prepare a solution with deionized water. Add semi-finished catalyst A to the solution, shake, and after the solution is completely absorbed, dry at 110°C for 3 hours and calcine at 500°C for 4 hours to obtain semi-finished catalyst B1.

[0146] (3) Weigh palladium nitrate, dissolve it in deionized water, adjust the pH to 1, then immerse the semi-finished catalyst B1 in the prepared Pd salt solution, immerse and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 400℃ for 6 hours to obtain the finished catalyst.

[0147] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 2.

[0148] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 450°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0149] Comparative Examples 1-3

[0150] The difference between Comparative Examples 1-3 and Example 1 is that the solution-loaded Pd is replaced with Ag.

[0151] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. 100 g of the carrier was calcined at high temperature for 4 hours. The calcination temperature and carrier properties are shown in Table 1.

[0152] Catalyst preparation:

[0153] (1) Weigh out nickel nitrate and copper chloride and dissolve them in deionized water. Add cyclohexane, Triton X-100 and n-butanol and stir thoroughly to form a microemulsion. Impregnate 100g of the carrier into the prepared microemulsion. After impregnation for 1 hour, wash with deionized water until neutral. Dry at 120°C for 2 hours and calcine at 550°C for 5 hours to obtain the semi-finished catalyst A1.

[0154] (2) Weigh ferric chloride and prepare a solution with deionized water. Add the semi-finished catalyst A1 to the solution, shake, and after the solution is completely absorbed, dry at 110°C for 3 hours and calcine at 500°C for 4 hours to obtain the semi-finished catalyst B1.

[0155] (3) Weigh silver nitrate, dissolve it in deionized water, adjust the pH to 1, then immerse the semi-finished catalyst B1 in the prepared Ag salt solution, immerse and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 400℃ for 6 hours to obtain the finished catalyst.

[0156] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 2.

[0157] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 200°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0158] Comparative Example 2-1

[0159] In Comparative Example 2-1, there was no loading of Pd solution.

[0160] Carrier: A commercially available bimodal spherical carrier with a diameter of 4 mm was used, consisting of 90% alumina and 10% titanium oxide. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 1.

[0161] Catalyst preparation:

[0162] (1) Weigh out nickel nitrate and copper nitrate, dissolve them in deionized water, add cyclohexane, 14.3g Triton X-100, and 13.60g n-hexanol, and stir thoroughly to form a microemulsion. Add the support to the prepared microemulsion and impregnate for 1 hour, then wash with deionized water until neutral, dry at 120℃ for 2 hours, and calcine at 550℃ for 5 hours. Obtain the semi-finished catalyst A1.

[0163] (2) Weigh out ferric nitrate and dissolve it in water. Add the semi-finished catalyst A1 to the Fe salt solution, impregnate and adsorb for 1 hour, dry at 110°C for 2 hours, and calcine at 400°C for 6 hours to obtain the semi-finished catalyst B1.

[0164] (3) Weigh palladium nitrate and dissolve it in water. Add cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst B1 to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. The finished catalyst is obtained.

[0165] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 2.

[0166] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 180°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0167] Comparative Example 2-2

[0168] In Comparative Example 2-2, there was no Fe loading in the solution, but the Pd content in the solution was relatively high.

[0169] Carrier: A commercially available bimodal spherical carrier with a diameter of 4 mm was used, consisting of 90% alumina and 10% titanium oxide. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 1.

[0170] Catalyst preparation:

[0171] (1) Weigh out nickel nitrate and copper nitrate, dissolve them in deionized water, add cyclohexane, 14.3g Triton X-100, and 13.60g n-hexanol, and stir thoroughly to form a microemulsion. Add the support to the prepared microemulsion and impregnate for 1 hour, then wash with deionized water until neutral, dry at 120℃ for 2 hours, and calcine at 550℃ for 5 hours. Obtain the semi-finished catalyst A1.

[0172] (2) Weigh palladium nitrate, dissolve it in deionized water, adjust the pH to 1, then immerse the semi-finished catalyst A1 in the prepared Ag salt solution. After immersion and adsorption for 1 hour, dry at 110°C for 2 hours and calcine at 400°C for 6 hours to obtain the semi-finished catalyst B1.

[0173] (3) Weigh palladium nitrate and dissolve it in water. Add cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst B1 to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours. The finished catalyst is obtained.

[0174] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 2.

[0175] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 180°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0176] Comparative Example 3

[0177] In Comparative Example 3, there was no loading of microemulsion Ni, Cu, or Pd.

[0178] Carrier: A commercially available spherical alumina carrier with a single-peak pore distribution and a diameter of 4 mm was used. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 1.

[0179] Catalyst preparation:

[0180] (1) Weigh ferric chloride and dissolve it in deionized water. Immerse the carrier in the prepared solution. After the solution is completely absorbed, dry at 100°C for 4 hours and calcine at 400°C for 6 hours to obtain the required catalyst semi-finished product, catalyst A1.

[0181] (2) Weigh palladium chloride salt and dissolve it in water to adjust the pH to 3. Add the weighed support of semi-finished catalyst A1 to the salt solution of Pd, impregnate and adsorb for 2 hours, dry at 120℃ for 1 hour, and calcine at 450℃ for 4 hours to obtain the finished catalyst.

[0182] The contents of each component in the catalyst are shown in Table 2.

[0183] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 350°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0184] Comparative Example 4

[0185] In Comparative Example 4, Ni and Cu in the microemulsion were replaced by Ni and Zn.

[0186] Carrier: A commercially available bimodal spherical alumina carrier with a diameter of 4 mm was used. After high-temperature calcination for 4 hours, 100 g of the carrier was weighed, and its physical properties are shown in Table 1.

[0187] Catalyst preparation:

[0188] (1) Weigh ferric chloride and dissolve it in deionized water. Add the carrier to the prepared solution, dry at 110°C for 3 hours, and calcine at 500°C for 4 hours to obtain the semi-finished catalyst A1.

[0189] (2) Weigh palladium nitrate salt and dissolve it in water, adjust the pH to 2, add the semi-finished catalyst A1 to the salt solution of Pd, impregnate and adsorb for 1 hour, dry at 110℃ for 2 hours, and calcine at 400℃ for 6 hours to obtain the semi-finished catalyst B1.

[0190] (3) Weigh out nickel nitrate and zinc nitrate, dissolve them in water, add cyclohexane, Triton X-100, and 6.03 g of n-hexanol, and stir thoroughly to form a microemulsion. Add the semi-finished catalyst B1 to the prepared microemulsion and impregnate for 4 hours. Then wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours to obtain the semi-finished catalyst C1.

[0191] (4) Weigh palladium nitrate and dissolve it in water. Add cyclohexane, Triton X-100, and 6.03 g of n-hexanol and stir thoroughly to form a microemulsion. Add the semi-finished catalyst C1 to the prepared microemulsion and impregnate for 4 hours. Wash with deionized water until neutral, dry at 90°C for 4 hours, and calcine at 600°C for 2 hours to obtain the finished catalyst.

[0192] The particle size of the microemulsion prepared during the catalyst preparation process and the content of each component in the catalyst are shown in Table 2.

[0193] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 160°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0194] Before use, place it in a fixed-bed reactor and reduce it for 12 hours at 160°C using a mixed gas with a molar ratio of N2:H2 = 1:1.

[0195] Table 1 Catalyst Support Properties

[0196]

[0197] Table 2 Content of active components in catalysts

[0198]

[0199] The performance of the above catalyst was evaluated in a fixed-bed single-stage reactor. The composition of the reactants and the evaluation results are shown in Table 3.

[0200] Table 3. Material composition and results of hydrogenation for alkyne removal

[0201]

[0202] The reduction temperature peaks of the catalysts supported only on Ni / Cu and the catalysts supported on Pb-Ni / Cu as in Example 1 were measured. The reduction peak of the catalyst supported only on Ni / Cu was around 350°C, while the reduction temperature of the catalyst supported on Pb-Ni / Cu was around 150°C.

[0203] Of course, the present invention may have other various embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and modifications according to the present invention, but these corresponding changes and modifications should all fall within the protection scope of the claims of the present invention.

Claims

1. A process for the selective hydrogenation of trace amounts of ethyne in the methanol to olefins process, characterized in that, include: A hydrogenation catalyst was used to selectively hydrogenate and purify the methanol-to-ethylene product. The target of hydrogenation was trace amounts of acetylene contained in the overhead effluent of the methanol-to-ethylene product after alkaline washing, drying, demethanization, and deethane removal. The inlet temperature of the hydrogenation reactor was 25℃–90℃, the reaction pressure was 1.5–3.5 MPa, and the space velocity was 2000–10000 h⁻¹. -1 The H2 / C2H2 ratio is 1–20; the catalyst support is alumina or mainly alumina, and has a bimodal pore distribution structure; the catalyst contains at least Fe, Pd, Ni, and Cu, wherein Fe is supported in solution, Ni and Cu are supported in microemulsion, and Pd is supported in both microemulsion and solution. Based on 100% catalyst mass, the Fe content is 0.5–1.5%, the Pd content is 0.007–0.01%, the Ni content is 0.9–7.5%, the Cu to Ni weight ratio is 0.15–0.90, and the Pd content in the microemulsion-supported catalyst is 1 / 300–1 / 500 of the Cu content; wherein the Ni, Cu, and Pd supported in the microemulsion are mainly distributed in the macropores of the support. The catalyst has Fe as the main active component and Pd as the auxiliary active component. When the microemulsion is loaded, the microemulsion particle size is controlled to be greater than 80 nm and less than 950 nm.

2. The selective hydrogenation process of claim 1 wherein, The hydrogenation reactor is an adiabatic single-section bed.

3. The selective hydrogenation process of claim 1 wherein, The hydrogenation target is trace amounts of acetylene contained in the overhead effluent of the deethanizer after separation of methanol-to-ethylene products. The feed composition is: ethylene ≥ 99.9% by volume, acetylene 5-100 ppm, CO 1-10 ppm.

4. The selective hydrogenation process of claim 1 wherein, The Al2O3 support has an α, θ or a mixture thereof crystal form; the aluminum oxide content in the support is above 80 wt%, and the support also contains at least one of magnesium oxide and titanium oxide.

5. The selective hydrogenation process of claim 1 wherein, The specific surface area of the carrier is 1-7 m 2 / g and has a bimodal pore structure with a pore diameter of 50-80 nm for small pores and 680-950 nm for large pores.

6. The selective hydrogenation process of claim 1 wherein, The loading of Pd and Fe in the solution was carried out by supersaturation impregnation method, and the Pd and Fe were mainly distributed in small pores with a pore size between 50 and 80 nm.

7. The selective hydrogenation process of claim 1 wherein, The microemulsion loading process includes: dissolving the precursor salt in water, adding an oil phase, a surfactant, and a co-surfactant, and stirring thoroughly to form a microemulsion, wherein the oil phase is an alkane or cycloalkanes, the surfactant is an ionic surfactant and / or a nonionic surfactant, and the co-surfactant is an organic alcohol.

8. The selective hydrogenation process of claim 1 wherein, The hydrogenation reactor has an inlet temperature of 30℃~60℃, a reaction pressure of 2.0~3.0MPa, and a space velocity of 6000~9000h⁻¹. -1 The H2 / C2H2 ratio is 2 to 5; based on the mass of the catalyst (100%), the Fe content is 0.55 to 1.3%, the Pd content is 0.008 to 0.009%, the Ni content is 3.0 to 6.8%, the weight ratio of Cu to Ni is 0.2 to 0.7, and the Pd content in the microemulsion-loaded catalyst is 1 / 400 to 1 / 450 of the Cu content.

9. The selective hydrogenation process of claim 1 wherein, The preparation process of the catalyst specifically includes the following steps: (1) The loading of Fe was carried out by saturated impregnation. The Fe salt solution was prepared at 80-110% of the saturated water absorption rate of the support. After loading Fe, it was dried at 100-120℃ for 1-4 hours and calcined at 500-550℃ for 4-6 hours to obtain semi-finished catalyst A. (2) Dissolve the precursor salt of Pd in ​​water, adjust the pH to 1.5-2.5, add the semi-finished catalyst A into the salt solution of Pd, impregnate and adsorb for 0.5-4h, dry at 100-120℃ for 1-4h, and calcine at 400-550℃ for 2-6h to obtain the semi-finished catalyst B. (3) Dissolve the precursor salts of Ni and Cu in water, add oil phase, surfactant and co-surfactant, the weight ratio of surfactant and co-surfactant is 1.0 to 1.2, the weight ratio of water phase to oil phase is 4.8 to 6.8, the weight ratio of surfactant to oil phase is 0.08 to 0.30, stir thoroughly to form microemulsion, control the microemulsion particle size to be greater than 80 nm and less than 950 nm; add semi-finished catalyst B to the prepared microemulsion and impregnate for 0.5 to 4 hours, filter out the residual liquid, dry at 60 to 120 °C for 1 to 6 hours, calcine at 300 to 600 °C for 2 to 8 hours to obtain semi-finished catalyst C; (4) Dissolve the Pd precursor salt in water, add oil phase, surfactant and co-surfactant. The weight ratio of surfactant and co-surfactant is 1.0 to 1.2, the weight ratio of water phase to oil phase is 4.8 to 6.8, and the weight ratio of surfactant to oil phase is 0.08 to 0.

30. Stir thoroughly to form a microemulsion, and control the microemulsion particle size to be greater than 80 nm and less than 950 nm. Add the semi-finished catalyst C to the prepared microemulsion and impregnate for 0.5 to 4 hours. Filter out the residual liquid, dry at 60 to 120 °C for 1 to 6 hours, and calcine at 300 to 600 °C for 2 to 8 hours to obtain the desired catalyst.

10. The selective hydrogenation process according to claim 7 or 9, characterized in that, The surfactant is an ionic surfactant and / or a nonionic surfactant, the oil phase is a C6-C8 saturated alkane or cycloalkanes, and the co-surfactant is a C4-C6 alcohol.

11. The selective hydrogenation process of claim 10 wherein, The surfactant is a nonionic surfactant.

12. The selective hydrogenation process of claim 10 wherein, The surfactant is polyethylene glycol octylphenyl ether or hexadecyltrimethylammonium bromide.

13. The selective hydrogenation process of claim 10 wherein, The oil phase consists of cyclohexane and n-hexane.

14. The selective hydrogenation process of claim 10 wherein, The co-surfactant is n-butanol and / or n-pentanol.

15. The selective hydrogenation process according to claim 1 or 9, characterized in that, The order of Fe solution loading and Ni / Cu microemulsion loading is not limited. Fe solution loading can be performed before or after Ni / Cu microemulsion loading. The Pd microemulsion loading step is performed after the Ni and Cu microemulsion loading steps. The Pd solution loading step is performed after the Fe solution loading step.

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