WO2019183842A1 - Composite catalyst, preparation method therefor and method for preparing ethylene - Google Patents

Abstract

A composite catalyst, a preparation method therefor and a method for preparing ethylene. The composite catalyst comprises a zirconium-based oxide and a modified acidic molecular sieve, wherein the zirconium-based oxide has a mass content of 10 wt%-90 wt%, and the modified acidic molecular sieve has a mass content of 10 wt%-90 wt%; and the preparation method therefor is simple. The composite catalyst is used for preparing ethylene to break ASF distribution law for hydrocarbon in the Fischer-Tropsch (F-T) synthesis, wherein the selectivity of ethylene reaches 86%.

Description

Composite catalyst, preparation method thereof and preparation method of ethylene Technical field

The present application relates to a composite catalyst, a preparation method thereof and a preparation method of ethylene, and belongs to the field of synthesis gas to produce low carbon olefins.

Background technique

Ethylene is the world's largest production and consumption of basic chemical products. With the development of China's economy, domestic ethylene demand will continue to increase, but the existing production capacity is far from meeting demand. At present, ethylene is mainly obtained by cracking naphtha, and China's resource endowment is “rich coal, lean oil, and less gas”, which seriously restricts the development of downstream industries and poses a serious threat to national energy security. Therefore, the development of a method based on non-petroleum resources such as coal to produce ethylene has certain practical significance.

At present, the mature method for producing ethylene from syngas is an indirect method. The syngas is first converted to methanol, and the methanol is subjected to an MTO process to produce a mixed low olefin (C2-C4 olefin). The path has entered industrialization in China and has achieved great success. Compared with the indirect route of syngas to olefin by methanol, the direct synthesis of ethylene from syngas has the advantages of simple process and less equipment. Syngas can be directly produced from olefins by a classical Fischer-Tropsch process in which the catalyst is a supported metal catalyst. Generally, the maximum selectivity of the C2-C4 hydrocarbons is not more than 58%, and the maximum selectivity of the gasoline fraction C5-C11 is 45%, while a large amount of methane and high-carbon alkanes are formed. Therefore, how to selectively produce low-carbon olefins has always been a core problem that is difficult to overcome in this field. After years of continuous exploration and improvement by researchers at home and abroad, great progress has been made in this field, but the highest selectivity for low-carbon olefins is still no more than 61% (H.M.Torres Galvis et al., Science 2012, 335, 835-838).

Due to the great success of syngas in the preparation of low-carbon olefins from methanol, recent researchers have attempted to couple the two reactions of methanol synthesis and methanol to olefins with success. Although the coupling of the methanol reaction with the methanol to olefin reaction can significantly improve the selectivity of the lower olefins, the ethylene obtained in the prior art is still less selective in hydrocarbon species and does not have an ethylene selectivity of more than 25%. Therefore, the direct conversion of syngas to ethylene is extremely challenging.

Summary of the invention

According to an aspect of the present application, there is provided a composite catalyst which is applied to the synthesis of ethylene in one step and high selectivity for syngas, and breaks the distribution of hydrocarbon Anderson-Schulz-Flory (ASF) in Fischer-Tropsch (FT) synthesis. Regularity, in which the selectivity of ethylene reaches 86%.

The composite catalyst is characterized in that it comprises a zirconium-based oxide and a modified acidic molecular sieve; the composition thereof comprises, by mass percentage, the mass content of the zirconium-based oxide is 10 wt.% to 90 wt.%, and the quality of the modified acidic molecular sieve The content is 10wt.% to 90wt.%;

Wherein, the modified acidic molecular sieve is an acidic molecular sieve treated by a pre-adsorbed alkali.

Optionally, the upper limit of the mass content of the zirconium-based oxide is selected from the group consisting of 11 wt.%, 20 wt.%, 30 wt.%, 33.3 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 66.7 wt.%, 70 wt.%, 80 wt.% or 90 wt.%; lower limit selected from 10 wt.%, 20 wt.%, 30 wt.%, 33.3 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 66.7 wt.%, 70 wt. .%, 80 wt.% or 89 wt.%.

Optionally, the upper limit of the mass content of the modified acidic molecular sieve is selected from the group consisting of 11 wt.%, 20 wt.%, 30 wt.%, 33.3 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 66.7 wt.%, 70 wt.%, 80 wt.% or 90 wt.%; lower limit selected from 10 wt.%, 20 wt.%, 30 wt.%, 33.3 wt.%, 40 wt.%, 50 wt.%, 60 wt.%, 66.7 wt.%, 70 wt. .%, 80 wt.% or 89 wt.%.

Preferably, the step of pre-adsorbing alkali treatment comprises at least contacting the acidic molecular sieve with a gas containing an organic base for pre-adsorption alkali treatment.

Preferably, the upper temperature limit of the pre-adsorption alkali treatment is selected from 160 ° C, 200 ° C, 250 ° C, 300 ° C or 350 ° C; the lower limit is selected from 150 ° C, 200 ° C, 250 ° C, 300 ° C or 340 ° C.

Optionally, the upper time limit of the pre-adsorption base treatment is selected from 0.6 h, 1 h, 2 h, 3 h or 4 h; the lower limit is selected from 0.5 h, 1 h, 2 h, 3 h or 3.9 h.

Preferably, the pre-adsorption alkali treatment has a temperature of 150 to 350 ° C, and the pre-adsorption alkali treatment has a time of 0.5 to 4 h.

Optionally, the upper limit of the mass space velocity of the organic base-containing gas is selected from the group consisting of 400 mL·g ^-1 ·h ^-1 , 500 mL·g ^-1 ·h ^-1 , 1000 mL·g ^-1 ·h ^-1 , 2000 mL· g ^-1 ·h ^-1 , 3000mL·g ^-1 ·h ^-1 , 4000mL·g ^-1 ·h ^-1 , 5000mL·g ^-1 ·h ^-1 or 6000mL·g ^-1 ·h ^-1 ; From 300 mL·g ^-1 ·h ^-1 , 500 mL·g ^-1 ·h ^-1 , 1000 mL·g ^-1 ·h ^-1 , 2000 mL·g ^-1 ·h ^-1 , 3000 mL·g ^-1 ·h ^-1 4000 mL·g ^-1 ·h ^-1 , 4900 mL·g ^-1 ·h ^-1 or 5000 mL·g ^-1 ·h ^-1 .

As an embodiment, the organic base-containing gas includes a carrier gas and an organic base.

Preferably, the organic base is selected from the group consisting of trimethylamine, diethylamine, triethylamine, pyridine, pyridazine, pyrimidine, pyrazine, pyridine, imidazole, N-methylimidazole, N-ethylimidazole, N-propyl At least one of a group of imidazoles and N-isopropylimidazole.

Preferably, the carrier gas is at least one selected from the group consisting of nitrogen, helium, CO ₂ , argon, and hydrogen.

Optionally, the upper limit of the volume fraction of the organic base in the organic base-containing gas is selected from the group consisting of 0.2%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 10%; the lower limit is selected from 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, 9% or 9.9%.

Further preferably, the volume fraction of the organic base in the organic base-containing gas is from 0.1% to 10%.

Preferably, the step of pre-adsorbing alkali treatment comprises at least: activating the acidic molecular sieve in an inert gas atmosphere, then adjusting the temperature to a pre-adsorption alkali treatment temperature, and contacting the gas containing the organic base to pre-adsorb the alkali. After the treatment, the adsorption is saturated, and the mixture is purged to room temperature to obtain a modified acidic molecular sieve.

Optionally, the upper temperature limit of activation is selected from 320 ° C, 350 ° C, 400 ° C, 450 ° C or 480 ° C; the lower limit is selected from 300 ° C, 350 ° C, 400 ° C, 450 ° C or 500 ° C.

Optionally, the upper limit of the time of activation is selected from 3.2 h, 3.5 h, 4 h, 4.5 h or 5 h; the lower limit is selected from 3 h, 3.5 h, 4 h, 4.5 h or 4.8 h.

Preferably, the activation temperature is 300 to 500 ° C, and the activation time is 3 to 5 hours.

As a specific embodiment, the step of performing the pre-adsorption alkali treatment on the acidic molecular sieve comprises at least: the acidic molecular sieve needs to be subjected to pre-adsorption organic alkali treatment for a certain time by carrying the organic base at a certain space velocity and temperature; Wherein, the volume fraction of the organic base in the mixed gas is 0.1% to 10%, and the carrier gas may be any one of nitrogen, helium, CO ₂ , argon, hydrogen, or a mixture of any of them, pretreatment The gas mass space velocity ranges from 300 to 5000 mL·g ^-1 ·h ^-1 ; the organic base is trimethylamine, diethylamine, triethylamine, pyridazine, pyrimidine, pyrazine, pyridine, imidazole, N-methyl a mixture of any one or a combination of imidazole, N-ethylimidazole, N-propylimidazole, N-isopropylimidazole; the organic base pretreatment temperature ranges from 150 to 350 ° C, and the pretreatment time is 0.5 to 4h.

Preferably, the acidic molecule is screened from a molecular sieve having a MOR topology, a molecular sieve having a FER topology, a eutectic molecular sieve containing a MOR topology and a FER topology, a mixed crystal molecular sieve containing a MOR topology and a FER topology. At least one.

Preferably, the molecular sieve having the MOR topology is an H-MOR molecular sieve having a skeleton atom Si/Al ratio of 4 to 60.

Preferably, the molecular sieve having the FER topology is an H-ZSM-35 molecular sieve having a skeleton atom Si/Al ratio of 5 to 50.

Preferably, the acidic molecular sieve is at least one of a eutectic molecular sieve of H-MOR, H-ZSM-35, hydrogen type MOR and ZSM-35, and a mixed crystal molecular sieve of hydrogen type MOR and ZSM-35.

Preferably, the zirconium-based oxide is selected from at least one of the compounds having the formula of formula (I):

X _a M _b (ZrO ₂ ) _1-ab formula (I)

Wherein X in the formula (I) is an oxide of at least one of Si, Al, Ti, Ce, and La; and M is at least one of Cu, Ag, Zn, Mn, Y, Nb, Ga, In, and Cr. Oxide of the element;

Among them, a is 0.02 to 0.9, and b is 0.0 to 0.8.

The a, b are the molar proportions of the corresponding oxides in the total composition.

Preferably, the zirconium-based oxide is at least one of zirconium-based metal oxides.

Alternatively, the upper limit of a is selected from 0.1, 0.4, 0.5, 0.6, 0.8 or 0.9; the lower limit is selected from 0.02, 0.1, 0.4, 0.5, 0.6, or 0.8. Preferably, a is a value between 0.1 and 0.9.

Optionally, the upper limit of b is selected from 0.02, 0.05, 0.1, 0.4, 0.5 or 0.8; the lower limit is selected from 0, 0.02, 0.05, 0.1, 0.4 or 0.5. Preferably, b is a value between 0.1 and 0.8.

In another aspect of the present application, there is provided a method of preparing the composite catalyst comprising at least the following steps:

(1) obtaining a zirconium-based oxide;

(2) obtaining a modified acidic molecular sieve;

(3) The components comprising the zirconium-based oxide in the step (1) and the modified acidic molecular sieve in the step (2) are combined by ultrasonic assisted chemical compounding and/or physical compounding to obtain the composite catalyst.

Preferably, the method for obtaining the zirconium-based oxide in the step (1) comprises: preparing by at least one of a coprecipitation method, a dipping method, and a mechanical mixing method.

As an embodiment, the coprecipitation method includes at least the steps of: mixing a solution containing an element X element, an M' element, and a Zr element with a solution containing a precipitant in a cocurrent manner under stirring to control the pH of the system. The value is 7 to 9, and after aging, the solid phase is separated, washed, dried and calcined to obtain the zirconium-based oxide.

As an embodiment, the dipping method includes at least the steps of immersing the zirconia powder in a salt solution containing the X element and the M' element or immersing the zirconia powder and the oxide of X in a salt containing the M' element. The zirconia powder and the oxide of M' are immersed in the salt solution containing the X element in the solution; after the immersion, the solvent is removed, dried, and calcined to obtain the zirconium-based oxide.

M' is at least one selected from the group consisting of Cu, Ag, Zn, Mn, Y, Nb, Ga, In, and Cr.

Preferably, the aging time of the stirring in the coprecipitation method is 2 to 4 hours; and the baking condition is 400 to 600 ° C for 1 to 6 hours.

The agitation in the coprecipitation method is vigorous stirring. Preferably, the speed of stirring in the coprecipitation method is from 250 to 5000 rpm/min.

Preferably, the immersion time in the dipping method is 1 to 6 hours; the drying condition is 60 to 200 ° C for 1 to 10 hours; and the firing condition is 400 to 600 ° C for 1 to 6 hours.

Preferably, the X element, the M' element and the Zr element in the solution are independently derived from at least one of a nitrate, a hydrochloride, an acetate, an acetylacetonate, and a sulfate of the X element, the M element, and the Zr element. Kind.

Preferably, the precipitating agent is an alkali solution. Further preferably, the alkali liquid is at least one selected from the group consisting of ammonia water, ammonium carbonate, sodium carbonate, urea, NaOH, and KOH.

As a specific embodiment, the coprecipitation method includes the steps of: formulating at least one of the compound containing the X element, at least one of the compounds containing the M' element, and the Zr salt into an aqueous solution, which is referred to as a solution. A; one or any of ammonia, ammonium carbonate, sodium carbonate, urea, NaOH or KOH is formulated into aqueous solution B; under intense stirring, solution A and solution B are mixed in a cocurrent manner to adjust solution A and The flow rate of the solution B is controlled to be in the range of 7 to 9 in the mixed liquid; after the completion of the precipitation, the mixture is aged for 2 to 4 hours, filtered, washed, and dried; then calcined at a temperature ranging from 400 to 600 ° C for 1 to 6 hours.

As a specific embodiment, the impregnation method comprises the steps of: adding at least one of a compound containing an X element and a compound containing an M' element to a deionized water or an alcohol solution, Into solution C, the zirconia powder is immersed in the solution C, after immersion for 1 to 6 hours, the solvent is slowly evaporated to dryness, and then dried in an oven at 60 to 200 ° C for 1 to 10 hours; the dried powder is 400. The temperature range of -600 ° C is calcined for 1 to 6 hours.

Preferably, the ultrasonic assisted chemical compounding method in the step (3) comprises at least: ultrasonically separating a solution containing a zirconium-based oxide and a modified acidic molecular sieve, solid-liquid separation, drying and calcining the solid phase to obtain the composite catalyst. ;

The physical compounding method at least comprises: compounding a mixture containing a zirconium-based oxide and a modified acidic molecular sieve by at least one of mechanical mixing, ball milling, and shaking to obtain the composite catalyst.

Preferably, the ultrasonic assisted chemical compounding method has an ultrasonic time of 10 min to 3 h; a drying temperature of 60 to 150 ° C; and a calcination temperature of 300 to 650 ° C.

As a specific embodiment, the ultrasonic assisted chemical compounding method disperses the zirconium-based oxide and the modified acidic molecular sieve powder in water or an alcohol solution, and ultrasonically mixes for 10 min to 3 h, and the two are sufficiently mixed; The composite catalyst is obtained by filtration, drying and calcination; the drying temperature ranges from 60 to 150 ° C, and the calcination temperature ranges from 300 to 650 ° C.

As a specific embodiment, the physical compounding method refers to compounding a zirconium-based oxide with a modified acidic molecular sieve catalyst by a mixing method such as mechanical mixing, ball milling, and shaking mixing.

As a specific embodiment, the preparation method of the composite catalyst includes at least the following steps:

(1) preparing a zirconium-based metal oxide;

(2) The molecular sieve is subjected to ammonium exchange to prepare a hydrogen type molecular sieve, and the hydrogen type molecular sieve is pre-adsorbed alkali;

(3) The products in the steps (1) and (2) are combined by ultrasonic assisted chemical compounding or physical compounding to prepare a one-step ethylene catalyst for syngas.

The composite catalyst and/or the composite catalyst prepared according to the method is used for one-step synthesis of ethylene by synthesis gas.

In still another aspect of the present application, a method for preparing ethylene is provided, comprising at least the following steps:

The raw material gas containing the synthesis gas is passed through a reactor equipped with a composite catalyst to obtain ethylene;

Wherein the composite catalyst is selected from at least one of the composite catalyst and/or the composite catalyst prepared according to the method;

Wherein, the syngas comprises CO, H ₂ , CO ₂ , and the molar ratio satisfies:

CO: H ₂ : CO ₂ = 1: 0.2 to 4: 0 to 1.

Optionally, the upper temperature limit of the reaction is selected from 280 ° C, 300 ° C, 320 ° C, 350 ° C or 380 ° C; the lower limit is selected from 250 ° C, 280 ° C, 300 ° C, 320 ° C or 350 ° C.

Optionally, the upper limit of the reaction pressure is selected from 2.0 MPa, 2.5 MPa, 3.0 MPa, 5.0 MPa, 6.0 MPa, or 8.0 MPa; and the lower limit is selected from 1.0 MPa, 2.0 MPa, 2.5 MPa, 3.0 MPa, 5.0 MPa, or 6.0 MPa.

Optionally, the upper limit of the mass space velocity of the raw material gas is selected from the group consisting of 400 mL·g ^-1 ·h ^-1 , 500 mL·g ^-1 ·h ^-1 , 1000 mL·g ^-1 ·h ^-1 , 4000 mL·g ^-1 · h ^-1 , 8000mL·g ^-1 ·h ^-1 or 10000mL·g ^-1 ·h ^-1 ; lower limit is selected from 300mL·g ^-1 ·h ^-1 , 400mL·g ^-1 ·h ^-1 , 500mL· g ^-1 ·h ^-1 , 1000 mL·g ^-1 ·h ^-1 , 4000 mL·g ^-1 ·h ^-1 or 8000 mL·g ^-1 ·h ^-1 .

Preferably, the reaction temperature is 250 to 380 ° C, the pressure is 1.0 to 8.0 MPa, and the gas mass space velocity is 300 to 10000 mL·g ^-1 ·h ^-1 .

The preparation method of the ethylene is that the synthesis gas is ethylene in one step and the selectivity is 86%.

Preferably, the feed gas further includes an inert gas.

Preferably, the inert gas is selected from at least one of nitrogen, argon, helium, and methane.

Preferably, the volume content of the inert gas in the mixed gas is ≤10%.

Optionally, the upper limit of the volume content of the inert gas in the mixed gas is selected from 1%, 3%, 5%, 8% or 10%; and the lower limit is selected from 0%, 1%, 3%, 5% or 8 %.

Preferably, the inert gas has a volume content of 0% to 10% in the mixed gas.

Optionally, the upper limit of the molar ratio of CO and H ₂ is selected from 1/0.3, 1/0.5, 1/1, 1/3 or 1/4; the lower limit is selected from 1/0.2, 1/0.3, 1/0.5 , 1/1 or 1/3.

Preferably, the reactor is at least one of a fixed bed reactor, a fluidized bed reactor, and a moving bed reactor.

As a specific embodiment, the composite catalyst is used for a method for synthesizing ethylene into one step, and at least comprises the steps of: passing a raw material gas containing synthesis gas through a reactor equipped with a composite catalyst, under a certain reaction condition, one step. Synthetic ethylene; the synthesis gas is CO, H ₂ and CO ₂ and other gases, wherein the molar ratio of CO, H ₂ and CO ₂ is: CO/H ₂ /CO ₂ =1/X'/Y' (wherein X'=0.2～4;Y′=0～1); the reaction temperature is preferably 250-380° C.; other gases are selected from one or more of inert gas nitrogen, argon, helium and methane, which are in the raw materials. The volume content in the gas is less than 10%; the reaction pressure is preferably 1.0 to 8.0 MPa, and the gas velocity is preferably 300 to 10000 mL·g ^-1 ·h ^-1 .

The synthesis gas in the present application produces ethylene in a one-step process to give an ethylene selectivity of greater than 40%.

In the present application, "H-MOR molecular sieve" means a hydrogen type mordenite molecular sieve which can be produced by hydrogenating a molecular sieve by a conventional production method in the art.

In the present application, "H-ZSM-35 molecular sieve" means a hydrogen type ZSM-35 molecular sieve which can be produced by hydrogenating a molecular sieve by a conventional preparation method in the art.

In the present application, all conditions relating to the numerical range may be independently selected from any intermediate range within the stated numerical range.

In the present application, all conditions involving numerical ranges include endpoint values unless otherwise stated.

The beneficial effects that can be produced by this application include:

1. In the present application, a methanol synthesis catalyst is combined with a carbonylation catalyst, which has outstanding characteristics such as high ethylene selectivity (up to 86%), and low generation of methane and high carbon hydrocarbons.

2. The preparation process of the catalyst in the present application is simple and easy to obtain.

3. The one-step preparation of ethylene in the synthesis gas provided in the present application has the advantages of mild reaction conditions, simple process, and the like, and has the potential of large-scale industrialization.

detailed description

The present application is described in detail below with reference to the embodiments, but the application is not limited to the embodiments.

Unless otherwise stated, the raw materials in this application are all commercially available and used without treatment.

In the examples, the elemental analysis of the sample XRF was performed by a Magix (PHILIPS) type X-ray fluorescence analyzer, and the fluorescence intensity of the standard sample was correlated with its standard composition by an IQ ⁺ non-standard quantitative analysis program, and the influence of the interference line was subtracted.

The conversion and selectivity in the examples are calculated as follows:

The CO conversion rate is calculated as: X(CO)=1-F(CO) _outlet /F(CO) _inlet , where F(CO) _outlet is the reactor outlet CO flow and F(CO) _inlet is the reactor inlet CO flow.

The hydrocarbon selectivity is calculated as: S(C _n H _m )=n*C _n H _m /Σ(n*C _n H _m ), and C _n H _m is the concentration of the hydrocarbon species at the outlet of the reactor, n is the number of C atoms in the hydrocarbon species, and m is the number of H atoms.

Example 1

Weigh 21.46g Zr(NO ₃ ) ₄ ·5H ₂ O, 11.90g Zn(NO ₃ ) ₂ ·6H ₂ O and 4.34g Ce(NO ₃ ) ₃ ·6H ₂ O in a beaker, add 150mL deionized water, The salt solution A was obtained by stirring. 23.55 g of ammonium carbonate was weighed into a beaker, 150 mL of deionized water was added, and the mixture was thoroughly stirred to obtain a precipitating agent alkali solution B. The salt solution A and the precipitant alkali solution B were mixed in a cocurrent manner under vigorous stirring, and the relative flow rates of the solutions A and B were adjusted to ensure that the pH of the precipitation mixture was maintained between 7 and 8. After the end of the coprecipitation, it was aged for 2 h. Thereafter, it was dried in an oven at 100 ° C for 6 hours, and calcined in a muffle furnace at 500 ° C for 4 hours to obtain a zirconium-based metal oxide. The composition of the zirconium-based oxide was (ZnO) _0.4 (CeO ₂ ) _0.1 (ZrO ₂ ) _0.5 by XRF elemental analysis.

H-MOR (Si/Al = 10) acidic molecular sieves were packed in a reactor, heated to 450 ° C for 4 h in a nitrogen atmosphere, and then cooled to 250 ° C. The H-MOR was pre-adsorbed with pyridine in a manner of carrying pyridine with nitrogen (the volume fraction of pyridine in the mixed gas was 1%, and the mass space velocity of the mixed gas was 6000 mL·g ^-1 ·h ^-1 ). After pyridine was adsorbed for 2 h, it was purged with nitrogen for 4 h and then cooled to room temperature. The treated H-MOR molecular sieve was taken out to obtain an acidic molecular sieve treated with a pre-adsorbed alkali.

The zirconium-based metal oxide powder (3.0 g) obtained above and the H-MOR molecular sieve (1.5 g) pre-adsorbed with pyridine were sufficiently ground and mixed by a ball mill. The mixed powder was tableted, crushed, and sieved to obtain a particulate catalyst of 20 to 40 mesh, and the catalyst was designated as ##. The content of the zirconium-based metal oxide in the 1# composite catalyst was 66.7 wt.%, and the molecular sieve mass content was 33.3 wt.%.

3g 1# catalyst was charged into the reactor, and the synthesis gas was used to prepare ethylene reaction under the following conditions: reaction temperature 300 ° C, reaction pressure 5.0 MPa, CO/H ₂ was 3/1, and raw material gas mass space velocity (GHSV) was 2300 mL·g ^-1 ·h ^-1 . The reaction product was analyzed online by gas chromatography, and the analysis results are shown in Table 1.

Table 1 Example 1 catalyst reaction results

Catalyst number	CO conversion rate (%)	Ethylene selectivity (%)	Ethane selectivity (%)	Methane selectivity (%)
1#	15.2	81	3.0	1.2

Example 2

A zirconium-based oxide was obtained by the same preparation method and preparation conditions as in Example 1. The specific preparation conditions of the modified H-MOR molecular sieve are shown in Table 2 below, and the rest of the operations were the same as in Example 1. The method and conditions for preparing the composite catalyst by the CO hydrogenation catalyst and the modified H-MOR molecular sieve are the same as in the first embodiment.

Table 2

Catalyst 4#: The difference from Example 1 is that the carrier gas during the preparation of the modified H-MOR molecular sieve is CO ₂ .

Catalyst 5#: The difference from Example 1 is that the carrier gas during the preparation of the modified H-MOR molecular sieve is hydrogen.

Among them, the catalysts 2# to 5# were subjected to methanol carbonylation hydrogenation to obtain ethylene by the method and conditions described in Example 1, and the obtained ethylene had high selectivity and less generation of methane and high carbon hydrocarbons.

Example 3

The zirconium-based metal oxide is prepared by the impregnation method. The specific steps are as follows: 11.90 g of Zn(NO ₃ ) ₂ ·6H ₂ O is weighed into a beaker, 150 mL of deionized water is added, and the salt solution C is stirred to obtain 6.16 g of zirconia powder. And 0.79 g of titanium oxide was immersed in the solution C, and after immersing for 5 hours, the solvent was slowly evaporated to dryness, and after preliminary drying, it was dried in an oven at 100 ° C for 10 hours. The dried solid powder was calcined at a temperature of 550 ° C for 4 h. A zirconium-based metal oxide having a composition of (ZnO) _0.4 (TiO ₂ ) _0.1 (ZrO ₂ ) _{0.5 was obtained} .

Except that the preparation method of the zirconium-based oxide was different from that of Example 1, the other steps were the same as those of Example 1, and the catalyst obtained finally was recorded as 6#. Under the same reaction conditions as in Example 1, the 6# catalyst was evaluated, and the reaction product was analyzed by gas chromatography on-line, and the analysis results are shown in Table 3.

Table 3 Example 3 catalyst reaction evaluation results

Catalyst number	CO conversion rate (%)	Ethylene selectivity (%)	Ethane selectivity (%)	Methane selectivity (%)
6#	12.5	80.0	3.0	2.4

Example 4

The zirconium-based metal oxides of different metal compositions and different contents are prepared by a coprecipitation method or a dipping method, wherein the composition of the zirconium-based oxide is different from that of the first embodiment and the third embodiment, and the remaining operations and conditions of the coprecipitation method are the same as those in the first embodiment. The remaining operations and conditions of the impregnation method are the same as those in Example 3. The obtained catalysts were respectively referred to as 7# to 17#, and the specific compositions of the respective catalysts are shown in Table 4. Under the same reaction conditions as in Example 1, the catalyst No. 7#-17# was evaluated, and the reaction product was analyzed by gas chromatography on-line, and the analysis results are shown in Table 4.

Table 4 Example 4 catalyst reaction results

The composition of the zirconium-based oxide sample was measured by XRF.

Example 5

The molecular sieve topology, the molecular sieve Si/Al, the type of pre-adsorbed alkali and the effect of the mass content of zirconium-based metal oxide and acidic molecular sieve on the synthesis gas to ethylene were investigated. The composition and preparation of the zirconium-based metal oxide were the same as in Example 1, and the preparation and evaluation conditions of the composite catalyst were in accordance with Example 1. The reaction product was analyzed by gas chromatography on-line, and the results are shown in Table 5.

Table 5 Example 5 catalyst evaluation results

Wherein, the FER type topological molecular sieve is H-ZSM-35 molecular sieve.

Example 6

The composition and preparation method of the zirconium-based oxide in this embodiment are the same as those in the examples.

MOR (Si/Al = 10) molecular sieves were packed in a reactor, heated to 450 ° C for 4 h in a nitrogen atmosphere, and then cooled to 250 ° C. The H-MOR was pre-adsorbed with pyridine in a manner of carrying pyridine with nitrogen (the volume fraction of pyridine in the mixed gas was 1%, and the mass space velocity of the mixed gas was 6000 mL·g ^-1 ·h ^-1 ). After pyridine was adsorbed for 2 h, it was purged with nitrogen for 4 h and then cooled to room temperature. The treated H-MOR molecular sieve was taken out to obtain a molecular sieve subjected to pre-adsorption alkali treatment.

In the preparation of the composite catalyst, the modified H-MOR molecular sieve of Example 1 was replaced with the above-mentioned pre-adsorbed alkali-treated molecular sieve, and the rest was the same as in Example 1 to obtain a composite catalyst 28#.

3g 28# catalyst was charged into the reactor, and the synthesis gas was used to prepare ethylene reaction under the following conditions: reaction temperature 300 ° C, reaction pressure 5.0 MPa, CO/H ₂ was 3/1, and raw material gas mass space velocity (GHSV) was 2300 mL·g ^-1 ·h ^-1 . The reaction product was analyzed online by gas chromatography, and the analysis results are shown in Table 6.

Table 6 Example 6 catalyst reaction results

Catalyst number	CO conversion rate (%)	Ethylene selectivity (%)	Ethane selectivity (%)	Methane selectivity (%)
28#	13.2	70.1	2.8	1.5

Example 7

The effect of the content of zirconium-based metal oxides and acidic molecular sieve oxides on the synthesis of ethylene in synthesis gas was investigated. In addition to changing the relative content of zirconium-based metal oxides and molecular sieves, other conditions including zirconium-based metal oxide composition, preparation process, and evaluation conditions for composite catalysts are consistent with Example 1, and the reaction products are analyzed by gas chromatography on-line. 7 is shown.

Table 7 Example 7 Different Catalyst Reaction Evaluation Results

Example 8

The catalytic performance of the 1# composite catalyst at a reaction temperature of 250 ° C, 280 ° C, 320 ° C, and 380 ° C was examined, and other evaluation conditions were in accordance with Example 1 except for the reaction temperature. The reaction product was analyzed online by gas chromatography, and the results are shown in Table 8.

Table 8 Evaluation results of 1# catalyst at different temperatures

Example 9

The effect of the molar composition of the raw materials on the ethylene reaction of the synthesis gas was examined, and the evaluation conditions were the same as those in Example 1 except that the molar ratio of the gas was changed. The raw material gas molar ratio is CO/H ₂ /CO ₂ =1/X'/Y', and the X' and Y' values and their evaluation results under the respective conditions are shown in Table 9.

Table 9 Results of ethylene production from syngas with different feed gas conditions

Example 10

Under the conditions of different reaction total pressures of 1.0, 2.5, 3.0, 6.0 and 8.0 MPa, the influence of reaction pressure on the reaction of synthesis gas to ethylene was investigated. The catalyst was 1# catalyst, and other conditions were the same as those in Example 1 except for the reaction pressure. The reaction products were analyzed on-line by gas chromatography, and the results are shown in Table 10.

Table 10 Results of ethylene reaction from synthesis gas at different reaction pressures

Example 11

Under the different reaction gas space velocities of 300, 4000, 8000 and 10000 mL/g _cat · h, the effects of gas space velocity on the synthesis gas production of ethylene were investigated. The catalyst was 1#, except for gas space velocity, other conditions and examples. 1 Consistent, the reaction products were analyzed online by gas chromatography, and the results are shown in Table 11.

Table 11 Results of ethylene production from synthesis gas at different reaction space velocities

Example 12

The catalyst was a ## sample, and the reactors were a fluidized bed reactor and a moving bed reactor, respectively, and the other conditions were the same as in Example 1. The reaction product was analyzed online by gas chromatography, and the results are shown in Table 12.

Table 12 Reaction results in different reactors of 1# composite catalyst

Reactor type	CO conversion rate (%)	Ethylene selectivity (%)	Ethane selectivity (%)	Methane selectivity (%)
Fluidized bed	14.3	80.2	4.4	2.3
Moving bed	16.3	81.2	3.5	3.4

The above description is only a few examples of the present application, and is not intended to limit the scope of the application. However, the present application is disclosed in the preferred embodiments, but is not intended to limit the application, any person skilled in the art, It is within the scope of the technical solution to make a slight change or modification with the technical content disclosed above, which is equivalent to the equivalent embodiment, without departing from the technical scope of the present application.

Claims (20)

1. A composite catalyst comprising a zirconium-based oxide and a modified acidic molecular sieve;

   The zirconium-based oxide has a mass content of 10 wt.% to 90 wt.%, and the modified acidic molecular sieve has a mass content of 10 wt.% to 90 wt.%;

   Wherein, the modified acidic molecular sieve is an acidic molecular sieve treated by a pre-adsorbed alkali.
2. The composite catalyst according to claim 1, wherein the step of pre-adsorbing alkali treatment comprises at least contacting the acidic molecular sieve with a gas containing an organic base for pre-adsorption alkali treatment.
3. The composite catalyst according to claim 1 or 2, wherein the pre-adsorption alkali treatment temperature is 150 to 350 ° C, and the pre-adsorption alkali treatment time is 0.5 to 4 h, and the mass of the organic alkali-containing gas is used. The space velocity is 300 to 6000 mL·g ^-1 ·h ^-1 .
4. The composite catalyst according to claim 2, wherein the organic base-containing gas comprises a carrier gas and an organic base;

   The carrier gas is selected from at least one of nitrogen, helium, CO ₂ , argon, and hydrogen;

   The organic base is selected from the group consisting of trimethylamine, diethylamine, triethylamine, pyridazine, pyrimidine, pyrazine, pyridine, imidazole, N-methylimidazole, N-ethylimidazole, N-propylimidazole, N- At least one of isopropyl imidazole;

   The volume fraction of the organic base in the organic base-containing gas is from 0.1% to 10%.
5. The composite catalyst according to claim 2, wherein the step of pre-adsorbing alkali treatment comprises at least: activating the acidic molecular sieve in an inert gas atmosphere; and then adjusting the temperature to a pre-adsorption alkali treatment temperature, The pre-adsorption alkali treatment is carried out in contact with a gas containing an organic base; after the adsorption is saturated, the mixture is purged to room temperature to obtain a modified acidic molecular sieve.
6. The composite catalyst according to claim 5, wherein the activation temperature is 300 to 500 ° C, and the activation time is 3 to 5 hours.
7. The composite catalyst according to claim 1, wherein the acidic molecule is selected from a molecular sieve having a MOR topology, a molecular sieve having a FER topology, a eutectic molecular sieve containing a MOR topology and a FER topology, and a MOR topology. At least one of a mixed crystal molecular sieve of a structure and an FER topology.
8. The composite catalyst according to claim 7, wherein the molecular sieve having a MOR topology is an H-MOR molecular sieve having a skeleton atom Si/Al ratio of 4 to 60;

   The molecular sieve having the FER topology is an H-ZSM-35 molecular sieve having a skeleton atom Si/Al ratio of 5 to 50.
9. The composite catalyst according to claim 1, wherein the zirconium-based oxide is at least one selected from the group consisting of compounds having the chemical formula of the formula (I):

   X _a M _b (ZrO ₂ ) _1-ab formula (I)

   Wherein X in the formula (I) is an oxide of at least one of Si, Al, Ti, Ce, and La; and M is at least one of Cu, Ag, Zn, Mn, Y, Nb, Ga, In, and Cr. Oxide of the element;

   Among them, a is 0.02 to 0.9, and b is 0.0 to 0.8.
10. The method for preparing a composite catalyst according to any one of claims 1 to 9, characterized in that it comprises at least the following steps:

    (1) obtaining a zirconium-based oxide;

    (2) obtaining a modified acidic molecular sieve;

    (3) The components comprising the zirconium-based oxide in the step (1) and the modified acidic molecular sieve in the step (2) are combined by ultrasonic assisted chemical compounding and/or physical compounding to obtain the composite catalyst.
11. The method for preparing a composite catalyst according to claim 10, wherein the method for obtaining the zirconium-based oxide in the step (1) comprises: performing at least one of a coprecipitation method, a dipping method, and a mechanical mixing method. preparation.
12. The method for producing a composite catalyst according to claim 11, wherein the coprecipitation method comprises at least the following steps: stirring a solution containing a X element, an M' element, and a Zr element with a solution containing a precipitating agent The mixture is mixed in a cocurrent manner, the pH of the control system is 7-9, and after aging, the solid phase is separated, washed, dried and calcined to obtain the zirconium-based oxide;

    The impregnation method includes at least the steps of: immersing the zirconia powder in a salt solution containing the X element and the M' element or immersing the zirconia powder and the oxide of X in a salt solution containing the M' element or zirconia The powder and the oxide of M' are immersed in a salt solution containing X element; after immersion, the solvent is removed, dried, and calcined to obtain the zirconium-based oxide;

    Wherein M' is at least one selected from the group consisting of Cu, Ag, Zn, Mn, Y, Nb, Ga, In, and Cr.
13. The method for preparing a composite catalyst according to claim 12, wherein the aging time in the coprecipitation method is 2 to 4 hours, and the firing condition is 400 to 600 ° C for 1 to 6 hours;

    The immersion time in the dipping method is 1 to 6 hours, the drying condition is 60 to 200 ° C for 1 to 10 hours, and the firing condition is 400 to 600 ° C for 1 to 6 hours.
14. The method for preparing a composite catalyst according to claim 12, wherein the X element, the M' element and the Zr element in the solution are independently derived from the nitrate, hydrochloride of the X element, the M' element and the Zr element. At least one of acetate, acetylacetonate, and sulfate.
15. The method for preparing a composite catalyst according to claim 10, wherein the ultrasonic assisted chemical compounding method in the step (3) comprises at least: ultrasonically modifying a solution containing a zirconium-based oxide and a modified acidic molecular sieve, and solidifying Separating, drying and calcining the solid phase to obtain the composite catalyst;

    The physical compounding method at least comprises: compounding a mixture containing a zirconium-based oxide and a modified acidic molecular sieve by at least one of mechanical mixing, ball milling, and shaking to obtain the composite catalyst.
16. The method for preparing a composite catalyst according to claim 15, wherein the ultrasonic assisted chemical compounding method has a time of 10 min to 3 h; a drying temperature of 60 to 150 ° C; and a calcination temperature of 300 to 650 ° C. .
17. A method for preparing ethylene, characterized in that it comprises at least the following steps:

    The raw material gas containing the synthesis gas is passed through a reactor equipped with a composite catalyst to obtain ethylene;

    Wherein the composite catalyst is at least one selected from the group consisting of the composite catalyst according to any one of claims 1 to 9 and/or the composite catalyst prepared according to the method according to any one of claims 10 to 16;

    Wherein, the syngas comprises CO, H ₂ , CO ₂ , and the molar ratio satisfies:

    CO: H ₂ : CO ₂ = 1: 0.2 to 4: 0 to 1.
18. The method for preparing ethylene according to claim 17, wherein the reaction temperature is 250 to 380 ° C, the pressure is 1.0 to 8.0 MPa, and the gas mass space velocity is 300 to 10000 mL·g ^-1 · h ^-1 .
19. The method for preparing ethylene according to claim 17, wherein the raw material gas further comprises an inert gas;

    The inert gas is selected from at least one of nitrogen, argon, helium, and methane;

    The volume content of the inert gas in the mixed gas is ≤10%.
20. The method for producing ethylene according to claim 17, wherein the reactor is at least one of a fixed bed reactor, a fluidized bed reactor, and a moving bed reactor.