Method for preparing aromatic hydrocarbons from feed gas containing carbon dioxide and hydrogen and logistics containing aromatic hydrocarbons

Abstract

The present invention relates to the field of preparation of aromatic hydrocarbons, and discloses a method for preparing aromatic hydrocarbons from a raw gas containing carbon dioxide and hydrogen, and a logistics containing aromatic hydrocarbons. The method comprises: a raw gas A containing carbon dioxide and hydrogen and a raw gas B containing carbon dioxide and hydrogen are subjected to countercurrent contact reaction in a bed filled with at least n stages of catalyst to obtain a logistics containing aromatic hydrocarbons; wherein n is an integer greater than or equal to 3; the catalyst in the catalyst bed comprises a metal oxide and a molecular sieve; along the flow direction of the raw gas A, the temperature of the first stage catalyst bed to the n-1 stage catalyst bed increases step by step, and the temperature of the n-stage catalyst bed is lower than the temperature of the n-1 stage catalyst bed. The method of the present invention can not only increase the conversion rate of carbon dioxide, but also reduce the C in the logistics containing aromatic hydrocarbons obtained by the method. 9+ Aromatic hydrocarbons account for up to 70-90 mol% of the total aromatic hydrocarbons.

Description

Technical Field

[0001] The present invention relates to the technical field of preparation of aromatic hydrocarbons, and in particular to a method for preparing aromatic hydrocarbons from raw gas containing carbon dioxide and hydrogen, and logistics containing aromatic hydrocarbons. Background Art

[0002] Aromatic hydrocarbons play an indispensable role in the national economy, and traditional production routes rely on non-renewable resources such as petroleum. With petroleum resources becoming increasingly scarce, a growing number of researchers are dedicated to developing new routes for aromatic hydrocarbon production to reduce dependence on petroleum resources. Carbon dioxide is widely present in nature, and the greenhouse effect caused by large amounts of carbon dioxide emitted through processes such as fuel combustion and biological respiration is a serious environmental problem. Carbon dioxide capture and catalytic conversion technologies can be used to produce chemicals such as aromatic hydrocarbons using carbon dioxide as a carbon source, realizing the resource utilization of carbon dioxide. This not only reduces carbon emissions and alleviates environmental pressures, but also serves as a sustainable resource alternative.

[0003] Routes for converting carbon dioxide to aromatics include Fischer-Tropsch-like synthesis routes and conversion routes via methanol intermediates. The former converts carbon dioxide to carbon monoxide via the reverse water-gas shift reaction, which is then converted to hydrocarbon products via the Fischer-Tropsch synthesis reaction. However, since the product distribution in this process follows the Anderson-Schulz-Flory distribution, the selectivity of aromatic products is low. Another indirect synthesis route based on a methanol platform can draw on existing mature processes, but the production route is longer and the equipment investment is higher in actual production. To overcome the shortcomings of these two routes, a catalyst with carbon dioxide hydrogenation activity is coupled with a catalyst with aromatization activity, achieving a one-step conversion of carbon dioxide to aromatics with high selectivity.

[0004] CN110496639 and Nature Communications 2018, 9, 3457, respectively, reported on zinc-aluminum spinel coupled with acidic molecular sieve catalysts, achieving nearly 80% aromatics selectivity in a CO2 conversion system. ACSCatalysis 2019, 9, 895, achieved 34% CO2 conversion and 76% aromatics selectivity in a chromium oxide / ZSM-5 system. Modification of the molecular sieve can increase the BTX content, but at the expense of some activity and selectivity.

[0005] CN107840778A provides a method for producing aromatic hydrocarbons by hydrogenating carbon dioxide. The method utilizes an iron-based and modified or partially modified molecular sieve catalyst as a composite catalyst. This method for producing aromatic hydrocarbons by hydrogenating carbon dioxide improves the single-pass CO2 conversion rate, increases the selectivity of C5+ hydrocarbons and the selectivity of aromatic hydrocarbons in C5+ hydrocarbons, but has no significant effect on the specific distribution effect of aromatic hydrocarbons.

[0006] In general, multifunctional catalysts based on methanol synthesis can achieve high aromatics selectivity, but the regulation of aromatics distribution remains a challenge. Summary of the Invention

[0007] The purpose of the present invention is to overcome the problem of difficulty in regulating the distribution of aromatic hydrocarbons in the prior art of preparing aromatic hydrocarbons by hydrogenation of carbon dioxide, and to provide a method for preparing aromatic hydrocarbons from a feed gas containing carbon dioxide and hydrogen. This method can not only improve the conversion rate of CO2 and the selectivity of aromatic hydrocarbons, but also can make the C 9+ Aromatic hydrocarbons account for as much as 70-90 mol%, of which C9 aromatic hydrocarbons account for more than 60 mol%.

[0008] C 9+ Aromatic hydrocarbons can be used as oil blending components, 9+ Aromatic hydrocarbons enter the heavy aromatic hydrocarbon comprehensive utilization device and can be separated to obtain a single component of solvent oil. The inventors found in their research that it is difficult to control the distribution of aromatic hydrocarbon products due to the side reactions that easily occur on the outer surface of the molecular sieve. In the prior art, the selectivity of C6-C8 aromatic hydrocarbons is increased by improving the molecular sieve, but this places extremely high demands on the catalyst. However, there are few reports on improving the selectivity of C6-C8 aromatic hydrocarbons in the hydrogenation of carbon dioxide. 9+ Related processes for aromatics selectivity and proportion. In addition, in the existing technology, many studies have shown that the selectivity of aromatics will be reduced when regulating the distribution of aromatics.

[0009] In order to achieve the above-mentioned objectives, the first aspect of the present invention provides a method for producing aromatic hydrocarbons from a raw gas containing carbon dioxide and hydrogen, the method comprising: a raw gas A containing carbon dioxide and hydrogen and a raw gas B containing carbon dioxide and hydrogen are subjected to countercurrent contact reaction in a bed filled with at least n stages of catalyst to obtain a logistics containing aromatic hydrocarbons; wherein n is an integer greater than or equal to 3; the catalyst in the catalyst bed comprises a metal oxide and a molecular sieve; along the flow direction of the raw gas A, the temperature of the first stage catalyst bed to the n-1 stage catalyst bed increases step by step, and the temperature of the n-1 stage catalyst bed is lower than the temperature of the n-1 stage catalyst bed.

[0010] The second aspect of the present invention provides an aromatic hydrocarbon-containing stream obtained by the above method.

[0011] Preferably, the C 9+ Aromatic hydrocarbons account for 70-90 mol% of the total aromatic hydrocarbons.

[0012] Preferably, in the aromatics-containing stream, the proportion of C9 aromatics in the total aromatics is not less than 60 mol%.

[0013] The method for producing aromatics from feed gas containing carbon dioxide and hydrogen and the logistics containing aromatics of the present invention have at least the following advantages:

[0014] It can regulate the distribution of aromatics in the logistics containing aromatics, especially it can increase the C 9+ The proportion of aromatics in the total aromatics, while achieving the regulation of aromatics distribution, the method of the present invention can also obtain a higher carbon dioxide conversion rate and aromatics selectivity. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 The present invention relates to an operating process for producing aromatics from feed gas containing carbon dioxide and hydrogen according to a preferred embodiment of the present invention.

[0016] Description of Reference Numerals

[0017] 1 Raw gas A inlet 2 Raw gas B inlet

[0018] 31 Catalyst upper bed 32 Catalyst middle bed

[0019] 33 Catalyst lower bed DETAILED DESCRIPTION

[0020] The endpoints of the ranges and any values ​​disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0021] A first aspect of the present invention provides a method for producing aromatic hydrocarbons from a feed gas containing carbon dioxide and hydrogen, the method comprising: a feed gas A containing carbon dioxide and hydrogen and a feed gas B containing carbon dioxide and hydrogen are subjected to countercurrent contact reaction in a bed filled with at least n stages of catalyst to obtain a flow containing aromatic hydrocarbons; wherein n is an integer greater than or equal to 3; the catalyst in the catalyst bed comprises a metal oxide and a molecular sieve; and along the flow direction of the feed gas A, the temperature of the catalyst bed increases step by step from the first stage to the n-1 stage, and the temperature of the n-1 stage catalyst bed is lower than the temperature of the n-1 stage catalyst bed.

[0022] According to the present invention, those skilled in the art will understand that "countercurrent contact" means that raw gas A and raw gas B enter the reactor from opposite directions of the reactor filled with a catalyst bed, and then contact in the catalyst bed to obtain a logistics containing aromatic hydrocarbons and lead out through the bottom of the reactor. In order to prevent the backflow of raw gas A / B, a one-way valve may be provided on the pipeline for introducing raw gas A / B. For example, raw gas A enters the reactor from the upper part or top of the reactor, and raw gas B enters the reactor from the lower part or bottom of the reactor; or raw gas A enters the reactor from the lower part or bottom of the reactor, and raw gas B enters the reactor from the upper part or top of the reactor; wherein the structure of the reactor is a commonly used structure in the art. In order to realize the introduction and withdrawal of various materials in the present invention, pipelines and valves can be provided on the reactor as needed, and the present invention has no special limitation on this.

[0023] According to the present invention, it can be understood that, in the present invention, the catalyst bed that the raw gas A contacts for the first time is recorded as the first-stage catalyst bed.

[0024] In the present invention, by loading n-stage catalyst beds (n is an integer greater than or equal to 3) in stages, and controlling the temperature of the first-stage catalyst bed to the n-1-stage catalyst bed to increase step by step, the temperature of the n-stage catalyst bed is lower than the temperature of the n-1-stage catalyst bed, the conversion rate of carbon dioxide can be increased, and the C 9+ The inventors speculate that in the method of the present invention, the raw gas A first generates a mixture containing aromatics in the catalyst bed, and the raw gas B first generates a material containing an alkylating agent such as methanol. The material containing the aromatic mixture and the material containing an alkylating agent such as methanol can better undergo alkylation, isomerization and disproportionation and other transalkylation reactions in the catalyst bed to generate C 9+ Aromatic hydrocarbons.

[0025] According to the present invention, the catalysts in each catalyst bed are not limited as long as the objectives of the present invention can be achieved. In some embodiments, the catalysts in the catalyst beds of stages 1 through (n-1) as a whole catalyst bed include metal oxides and molecular sieves. The aforementioned embodiments facilitate the complete reaction of carbon dioxide and hydrogen to form a stream containing an aromatic hydrocarbon mixture.

[0026] According to the present invention, in some embodiments, the catalyst in the nth catalyst bed comprises a metal oxide. This embodiment facilitates the production of an alkylating agent, such as methanol, which acts as an alkyl donor to undergo a transalkylation reaction with the stream of the aromatic hydrocarbon mixture generated in the first n-1th catalyst bed.

[0027] According to the present invention, those skilled in the art will understand that in order to enable catalysts of various levels to be better loaded into the reactor, the catalyst may be optionally shaped before loading the catalyst. For example, when the catalyst in the catalyst bed includes metal oxides and molecular sieves, the metal oxides and molecular sieves need to be mixed and shaped. In order to make the mixing more uniform, the metal oxide and molecular sieve powders may be uniformly mixed by grinding or the like. In order to make them better shaped, 10-30 wt% of a binder may be optionally added. When the catalyst bed includes only metal oxides or molecular sieves, they may be shaped separately. In order to make them better shaped, 10-30 wt% of a binder may be optionally added. The catalyst may be shaped by tableting or extrusion. Those skilled in the art may select a suitable shaping method according to their needs. The present invention has no special restrictions on them and will not elaborate on them here.

[0028] According to the present invention, in some preferred embodiments, the mass ratio of metal oxide to molecular sieve in the catalyst bed from the 1st to the n-1th stage is The above-mentioned embodiment is conducive to the further aromatization reaction and transalkylation reaction of the generated aromatic hydrocarbon mixture in the catalyst bed, which increases the selectivity of aromatic hydrocarbons and can also regulate the distribution of aromatic hydrocarbon product components, thereby increasing C 9+ The proportion of aromatics, especially C9 aromatics.

[0029] In the present invention, m 金属氧化物 Refers to the mass of metal oxides in the catalyst bed of this level, m 分子筛 Refers to the mass of the molecular sieve in the catalyst bed of this level.

[0030] According to the present invention, in some preferred embodiments, the difference in the mass ratio of metal oxide to molecular sieve in two adjacent catalyst beds is The above embodiment can optimize the carbon dioxide hydrogenation and aromatization reaction activity configuration in each bed by regulating the catalyst ratio in each stage, thereby improving the carbon dioxide hydrogenation to aromatics reaction efficiency.

[0031] According to the present invention, in some preferred embodiments, the metal oxide content in the n-1 stage catalyst bed is 0. The above embodiment is advantageous for the transalkylation reaction to produce C 9+ Move in the direction of aromatics.

[0032] According to the present invention, in some embodiments, the temperature of each catalyst bed is 250-550°C.

[0033] According to the present invention, as long as the purpose of the present invention can be achieved, the temperature of each catalyst bed is not particularly limited. In some preferred embodiments, the temperature difference between two adjacent catalyst beds in the first to n-1th stages is 20-200°C, preferably 50-150°C. The above embodiment is advantageous for further transalkylation reaction after the raw gas A generates a mixture containing aromatic hydrocarbons, thereby better controlling the distribution of aromatic hydrocarbon components and increasing C 9+ The proportion of aromatics, especially C9 aromatics.

[0034] According to the present invention, in some preferred embodiments, the temperature difference between the nth stage catalyst bed and the n-1th stage catalyst bed is 20-200°C, preferably 50-100°C. The above embodiment can be used to facilitate the conversion of feed gas B into a material containing an alkylating agent such as methanol, which can then be subjected to a transalkylation reaction with a mixture containing aromatic hydrocarbons, thereby achieving the goal of regulating the distribution of aromatic hydrocarbon components and increasing C 9+ The purpose of aromatic selectivity.

[0035] According to the present invention, as long as the purpose of the present invention can be achieved, the volume of each catalyst bed can be set as needed. In some embodiments, the volume ratio of the first stage catalyst bed to the nth stage catalyst bed is 1:2 to 20:1, preferably 3:1 to 10:1. The above embodiment can make the amount of the aromatic hydrocarbon mixture and the product first generated by the raw gas B more matched, which is more conducive to the regulation of the aromatic hydrocarbon components, thereby increasing C 9+ The proportion of aromatics, especially C9 aromatics.

[0036] According to the present invention, in some embodiments, the volume ratio of two adjacent catalyst beds in the first to n-1th catalyst beds is 1:2 to 10:1, preferably 1:1 to 5:1. The aforementioned embodiment is advantageous for optimizing the activity configuration of each bed stage, thereby improving the efficiency of the carbon dioxide hydrogenation to aromatics reaction.

[0037] According to the present invention, the total number of catalyst bed stages is not particularly limited as long as the objectives of the present invention can be achieved. However, due to process complexity considerations, in some embodiments, n is an integer of 3-10, preferably an integer of 3-5. The aforementioned embodiments can optimize the activity configuration of each bed stage, thereby improving the efficiency of the carbon dioxide hydrogenation to aromatics reaction.

[0038] According to the present invention, in some embodiments, the total content of carbon dioxide and hydrogen in the feed gas A is 50-100% by volume, preferably 80-100% by volume, and the inert gas is supplemented to 100% by volume.

[0039] According to the present invention, in some embodiments, the total content of carbon dioxide and hydrogen in the feed gas B is 20-100% by volume, preferably 50-100% by volume, and the inert gas is supplemented to 100% by volume.

[0040] According to the present invention, the specific type of inert gas can be selected as needed. In the present invention, nitrogen is used as the inert gas to illustrate the advantages of the present invention, but the present invention is not limited thereto.

[0041] According to the present invention, in some preferred embodiments, the molar ratio of hydrogen to carbon dioxide in feed gas B is not less than the molar ratio of hydrogen to carbon dioxide in feed gas A. The aforementioned embodiment can improve the selectivity of feed gas A in converting to aromatics, and enhance the activity of feed gas B in converting to alkylating agents such as methanol.

[0042] According to the present invention, in some embodiments, the molar ratio of hydrogen to carbon dioxide in the feed gas A is 0.5-6.0, preferably 1.0-3.0.

[0043] According to the present invention, in some embodiments, the molar ratio of hydrogen to carbon dioxide in the feed gas B is 0.5-6.0, preferably 1.0-4.0.

[0044] According to the present invention, an alkylating agent can be optionally added to the raw gas B as needed. In some embodiments, the raw gas B also includes an alkylating agent. The above embodiment can further enhance the transalkylation reaction of the material containing the aromatic hydrocarbon mixture and improve C 9+ The proportion of aromatics, especially C9 aromatics.

[0045] According to the present invention, as long as the purpose of the present invention can be achieved, the content of the alkylating agent in the raw gas B is not particularly limited. In some embodiments, the molar ratio of the alkylating agent to the carbon dioxide in the raw gas B is 0.01-10, preferably 0.01-1, calculated as the alkyl group provided.

[0046] According to the present invention, in an actual process, those skilled in the art may use a mixture of carbon dioxide and hydrogen in the feed gas B to carry out the alkylating agent and introduce the mixture into the reactor for reaction. Alternatively, the alkylating agent may be directly introduced into the reactor through a pipeline using a pump according to the ratio of the alkylating agent to the carbon dioxide in the feed gas B, while the mixture of carbon dioxide and hydrogen in the feed gas B is introduced into the reactor through the pipeline at the inlet of the feed gas B. The present invention has no particular limitation on this and will not be elaborated herein.

[0047] According to the present invention, as long as the purpose of the present invention can be achieved, there is no special requirement for the type of the alkylating agent. In some embodiments, the alkylating agent is selected from one or more of methanol, dimethyl ether and light olefins (such as C2-C4 olefins).

[0048] According to the present invention, as long as the purpose of the present invention can be achieved, the type of the metal oxide is not particularly limited. Those skilled in the art can select a metal oxide with appropriate catalytic activity based on the catalytic activity of the metal oxide. In some embodiments, the metal element in the metal oxide includes one or more of Group IB metal elements, Group IIB metal elements, Group IIIB metal elements, Group IIIA metal elements, rare earth metal elements, Group IVB metal elements, Group VIB metal elements and Group VIIB metal elements.

[0049] According to the present invention, in some preferred embodiments, the metal elements in the metal oxide include one or more of Zn, Y, Ga, In, Mn, Cu, Cr, La, Ce, Mo, Zr and Al.

[0050] According to the present invention, as long as the purpose of the present invention can be achieved, the type of the molecular sieve is not particularly limited. In some embodiments, the molecular sieve is a molecular sieve with a ten-membered ring structure or a twelve-membered ring structure.

[0051] According to the present invention, it can be understood that molecular sieves are divided into molecular sieves with a certain silicon-to-aluminum ratio and all-silicon molecular sieves without aluminum. The present invention has no special restrictions on this and will not be elaborated in the present invention. In addition, the silicon-to-aluminum ratio (Si / Al) involved in the present invention refers to the silicon-to-aluminum molar ratio.

[0052] According to the present invention, in some preferred embodiments, the molecular sieve is selected from one or more of ZSM-5, ZSM-11, Silicalite-1, Silicalite-2, Hβ and HY.

[0053] According to the present invention, when using molecular sieve catalysts and metal oxide catalysts, in order to increase the catalytic activity of the catalysts, those skilled in the art may perform reduction treatment on the catalysts as needed during use. In some embodiments, the catalyst in the catalyst bed is pretreated in a reducing atmosphere before the contact reaction.

[0054] According to the present invention, as long as the purpose of the present invention can be achieved, the reduction treatment method is not particularly limited. In the present invention, the catalyst in the catalyst bed is reduced with H2 at 350-420°C for 1-5h as an example to illustrate the advantages of the present invention.

[0055] According to the present invention, as long as the purpose of the present invention can be achieved, the conditions of the contact reaction are not particularly limited. In some embodiments, the conditions of the contact reaction include: the volume space velocity of the raw gas A is higher than the volume space velocity of the raw gas B. The above embodiment can make the amount of the product first generated by the mixture containing aromatic hydrocarbons and the raw gas B more matched, which is more conducive to the regulation of the aromatic hydrocarbon components, thereby increasing C 9+ The proportion of aromatics, especially C9 aromatics.

[0056] According to the present invention, in some preferred embodiments, the contact reaction conditions include: the volume space velocity ratio of the raw gas A to the raw gas B is 5:1 to 100:1, preferably 10:1 to 50:1. The above embodiment can make the amount of the product first generated by the mixture containing aromatic hydrocarbons and the raw gas B more matched, which is more conducive to the regulation of the aromatic hydrocarbon components, thereby increasing C 9+ The proportion of aromatics, especially C9 aromatics.

[0057] According to the present invention, in some preferred embodiments, the contact reaction conditions include: the volume space velocity of the raw gas A is 600-10000 mL g -1 h -1 .

[0058] According to the present invention, in some embodiments, the conditions for the contact reaction include: a reaction pressure of 1.0-8.0 MPa, preferably 2.0-6.0 MPa.

[0059] The second aspect of the present invention provides an aromatic hydrocarbon-containing stream obtained by the above method.

[0060] According to the present invention, in some preferred embodiments, in the aromatic hydrocarbon-containing stream, C 9+ Aromatic hydrocarbons account for 70-90 mol% of the total aromatic hydrocarbons.

[0061] According to the present invention, in some preferred embodiments, in the aromatics-containing stream, the proportion of C9 aromatics in the total aromatics is not less than 60 mol%.

[0062] In the present invention, the method of the present invention not only has a higher carbon dioxide conversion rate and aromatics selectivity, but also can better regulate the distribution of aromatic components, increase C 9+ The proportion of aromatic hydrocarbons.

[0063] According to the present invention, in some embodiments, when n is 3, combined with Figure 1 , illustrating the operation process of the method of the present invention:

[0064] like Figure 1As shown, raw gas A containing carbon dioxide and hydrogen enters the reactor from raw gas A inlet 1 at the top of the reactor, and raw gas B containing carbon dioxide and hydrogen enters the reactor from raw gas B inlet 1 at the bottom of the reactor. A countercurrent contact reaction is carried out in the three-stage catalyst bed loaded in the reactor (along the flow direction of raw gas A, namely, catalyst upper bed 31, catalyst middle bed 32, and catalyst lower bed 33) to obtain a logistics containing aromatics, and the logistics containing aromatics is drawn out from the bottom of the reactor.

[0065] The present invention will be described in detail below by way of examples. In the following examples:

[0066] The components of the feed gas A / B and the aromatic hydrocarbon-containing stream are obtained by online gas chromatography analysis, wherein a hydrogen flame detector is used to detect hydrocarbon products, and the amount of each hydrocarbon product is calculated based on its response factor.

[0067] in:

[0068] Conversion rate of carbon dioxide = (amount of carbon dioxide in feed gas A + amount of carbon dioxide in feed gas B - amount of carbon dioxide in product) / (amount of carbon dioxide in feed gas A + amount of carbon dioxide in feed gas B) × 100%;

[0069] N C含芳烃的物流 =Σ(amount of organic product i in the aromatics-containing stream × number of carbon atoms in the molecule of organic product i);

[0070] Selectivity of organic product i in the aromatics-containing stream = amount of substance of organic product i × number of carbon atoms in the molecule of organic product i / N C含芳烃的物流 ×100%

[0071] Aromatic selectivity in aromatics-containing logistics = C6 aromatics selectivity + C7 aromatics selectivity + C8 aromatics selectivity + C9 aromatics selectivity + C 10+ Aromatic selectivity;

[0072] C n The proportion of aromatics in total aromatics = C n Aromatic selectivity / aromatic selectivity in the aromatic stream × 100% (n is an integer greater than or equal to 6); C n+ Aromatic hydrocarbons include C n .

[0073] A 6-8 :A9:A 10 C6-C8 aromatics: C9 aromatics: C 10+ The molar ratio of aromatic hydrocarbons.

[0074] Example 1

[0075] like Figure 1 As shown, the reactor is filled with an upper catalyst bed 31 (molded by adding 20 wt% silica sol after mixing and grinding Cr2O3 and ZSM-5 with a Si / Al ratio of 100 in a mass ratio of 1:1) with a volume ratio of 10:3:2, a middle catalyst bed 32 (molded by adding 10 wt% silica sol to ZSM-5 with a Si / Al ratio of 100), and a lower catalyst bed 33 (molded by pressing Cr2O3 tablets) from top to bottom. The catalyst in the catalyst bed is pretreated with H2 at 400°C for 3 h.

[0076] The temperature of the catalyst upper bed 31 was set to 320°C, the temperature of the catalyst middle bed 32 was set to 400°C, and the temperature of the catalyst lower bed 33 was set to 300°C. The feed gas A containing 100% by volume of carbon dioxide and hydrogen (the molar ratio of hydrogen to carbon dioxide was 3:1, and the volume space velocity was 2000 mL g -1 h -1 ) The raw gas A inlet 1 at the top of the reactor enters the reactor, and the raw gas B containing 100% by volume of carbon dioxide and hydrogen (the molar ratio of hydrogen to carbon dioxide is 3:1, and the volume space velocity is 200 mL g - 1 h -1 ) The raw gas B inlet 2 at the bottom of the reactor enters the reactor and undergoes countercurrent contact reaction in the catalyst bed (reaction pressure is 4.0 MPa) to obtain a flow containing aromatic hydrocarbons, and the flow containing aromatic hydrocarbons is drawn out from the bottom of the reactor.

[0077] The results of carbon dioxide conversion, aromatics selectivity, and aromatics distribution are shown in Table 1.

[0078] Example 2

[0079] The reactor was filled from top to bottom with an upper catalyst bed layer (molded by adding 20 wt% silica sol after mixing and grinding Cr2O3 and ZSM-5 with a Si / Al ratio of 100 in a mass ratio of 1:1), a second catalyst bed layer (molded by adding 20 wt% silica sol after mixing and grinding Cr2O3 and ZSM-5 with a Si / Al ratio of 100 in a mass ratio of 1:2), a third catalyst bed layer (molded by adding 10% silica sol to ZSM-5 with a Si / Al ratio of 100), and a lower catalyst bed layer (molded by pressing Cr2O3 tablets). The catalysts in the catalyst beds were pretreated with H2 at 380°C for 4 h.

[0080] The temperature of the upper catalyst bed was set at 320°C, the temperature of the second catalyst bed was 350°C, the temperature of the third catalyst bed was 400°C, the temperature of the lower catalyst bed was 300°C, and the feed gas A containing 100% by volume of carbon dioxide and hydrogen (the molar ratio of hydrogen to carbon dioxide was 3:1, and the volume space velocity was 1500 mL g-1 h -1 ) enters the reactor from the feed gas A inlet at the top of the reactor, and feed gas B (molar ratio of hydrogen to carbon dioxide is 4:1, volume space velocity is 50 mL g) containing 80% by volume of carbon dioxide and hydrogen, alkylating agent (methanol, with a molar ratio of 1:10 to feed gas B calculated as CO2) and nitrogen (supplementing feed gas B to 100% by volume) -1 h -1 ) The raw gas B inlet at the bottom of the reactor enters the reactor and undergoes countercurrent contact reaction in the catalyst bed (reaction pressure is 4.0 MPa) to obtain a flow containing aromatic hydrocarbons, and the flow containing aromatic hydrocarbons is drawn out from the bottom of the reactor.

[0081] The results of carbon dioxide conversion, aromatics selectivity, and aromatics distribution are shown in Table 1.

[0082] Example 3

[0083] The reactor is filled with a catalyst bed with a volume ratio of 10:5:3:2 (GaZrO x After being mixed and ground with ZSM-5 with a Si / Al ratio of 120, 20wt% silica sol was added to form the catalyst), the second catalyst bed (GaZrO with a mass ratio of 1:2 and a Ga / Zr molar ratio of 1 / 4) x After being mixed and ground with ZSM-5 with a Si / Al ratio of 120, 20wt% silica sol was added to form the catalyst), the third catalyst bed (Hβ molecular sieve with a Si / Al ratio of 150 and 10% silica sol was added to form the catalyst), the lower catalyst bed (GaZrO with a Ga / Zr molar ratio of 1 / 2) x Tablet forming), the catalyst in the catalyst bed was pretreated with H2 at 380°C for 4h;

[0084] The temperature of the upper catalyst bed was set at 300°C, the temperature of the second catalyst bed was set at 320°C, the temperature of the third catalyst bed was set at 410°C, the temperature of the lower catalyst bed was set at 320°C, and the feed gas A containing 100% by volume of carbon dioxide and hydrogen (the molar ratio of hydrogen to carbon dioxide was 3:1, and the volume space velocity was 1500 mL g -1 h -1 ) enters the reactor from the feed gas A inlet at the top of the reactor, and feed gas B (molar ratio of hydrogen to carbon dioxide is 4:1, volume space velocity is 50 mL g) containing 80% by volume of carbon dioxide and hydrogen and nitrogen (the volume of feed gas B is supplemented to 100% by volume) -1 h -1) The raw gas B inlet at the bottom of the reactor enters the reactor and undergoes countercurrent contact reaction in the catalyst bed (reaction pressure is 5.0 MPa) to obtain a flow containing aromatic hydrocarbons, and the flow containing aromatic hydrocarbons is drawn out from the bottom of the reactor.

[0085] The results of carbon dioxide conversion, aromatics selectivity, and aromatics distribution are shown in Table 1.

[0086] Example 4

[0087] The reactor is filled with a catalyst bed with a volume ratio of 5:9:7:3:1 from top to bottom (ZnZrO x After being mixed and ground with ZSM-5 with a Si / Al ratio of 50, 15wt% silica sol was added to form the catalyst), the second catalyst bed (ZnZrO with a mass ratio of 2:3 and a Zn / Zr molar ratio of 1 / 8) x After being mixed and ground with ZSM-5 with a Si / Al ratio of 150, 10 wt% silica sol was added to form the catalyst), the third catalyst bed (ZnZrO with a mass ratio of 1:3 and a Zn / Zr molar ratio of 1 / 8) x After being mixed and ground with ZSM-5 with a Si / Al ratio of 200, 10 wt% silica sol was added to form the catalyst), the fourth catalyst bed (ZSM-11 molecular sieve with a Si / Al ratio of 200 and 10 wt% silica sol was added to form the catalyst), the lower catalyst bed (ZnZrO with a Zn / Zr molar ratio of 1 / 2) x Tablet forming), the catalyst in the catalyst bed was pretreated with H2 at 390°C for 4h;

[0088] The temperature of the upper catalyst bed was set at 300°C, the temperature of the second catalyst bed was set at 320°C, the temperature of the third catalyst bed was set at 350°C, the temperature of the fourth catalyst bed was set at 390°C, and the temperature of the lower catalyst bed was set at 300°C. The feed gas A containing 100% by volume of carbon dioxide and hydrogen (the molar ratio of hydrogen to carbon dioxide was 2:1, and the volume space velocity was 1200 mL g -1 h -1 ) enters the reactor from the feed gas A inlet at the top of the reactor, and feed gas B (molar ratio of hydrogen to carbon dioxide is 3:1, volume space velocity is 30 mL g) containing 80% by volume of carbon dioxide and hydrogen, alkylating agent (dimethyl ether, the molar ratio of the feed gas B calculated as CO2 is 1:20) and nitrogen (supplemented to 100% by volume) -1 h -1 ) The raw gas B inlet at the bottom of the reactor enters the reactor and undergoes countercurrent contact reaction in the catalyst bed (reaction pressure is 5.0 MPa) to obtain a flow containing aromatic hydrocarbons, and the flow containing aromatic hydrocarbons is drawn out from the bottom of the reactor.

[0089] The results of carbon dioxide conversion, aromatics selectivity, and aromatics distribution are shown in Table 1.

[0090] Example 5

[0091] The method of Example 1 is as follows, except that:

[0092] The temperature of the upper catalyst bed was set at 350°C, the temperature of the middle catalyst bed was set at 370°C, and the temperature of the lower catalyst bed was set at 300°C.

[0093] The results of carbon dioxide conversion, aromatics selectivity, and aromatics distribution are shown in Table 1.

[0094] Example 6

[0095] The method of Example 3 is different in that:

[0096] In the upper catalyst bed, the mass ratio of GaZrOx to ZSM-5 is 1:2; in the second catalyst bed, the mass ratio of GaZrOx to ZSM-5 is 1:1; in the third catalyst bed, the mass ratio of GaZrOx to ZSM-5 is 2:1.

[0097] The results of carbon dioxide conversion, aromatics selectivity, and aromatics distribution are shown in Table 1.

[0098] Example 7

[0099] The method of Example 4 is as follows, except that:

[0100] In the upper catalyst bed, the mass ratio of ZnZrOx to ZSM-5 is 5:1; in the second catalyst bed, the mass ratio of ZnZrOx to ZSM-5 is 1:1; in the third catalyst bed, the mass ratio of ZnZrOx to ZSM-5 is 1:3.

[0101] The results of carbon dioxide conversion, aromatics selectivity, and aromatics distribution are shown in Table 1.

[0102] Example 8

[0103] The method of Example 1 is as follows, except that:

[0104] The volume ratio of the catalyst upper bed layer, the catalyst middle bed layer and the catalyst lower bed layer is 15:1:1.

[0105] The results of carbon dioxide conversion, aromatics selectivity, and aromatics distribution are shown in Table 1.

[0106] Example 9

[0107] The method of Example 1 is as follows, except that:

[0108] The molar ratio of hydrogen to carbon dioxide in raw gas A is 3:1; the molar ratio of hydrogen to carbon dioxide in raw gas B is 1:1.

[0109] The results of carbon dioxide conversion, aromatics selectivity, and aromatics distribution are shown in Table 1.

[0110] Comparative Example 1

[0111] The method of Example 1 is as follows, except that:

[0112] The reactor was filled from top to bottom with an upper catalyst bed layer (mixed and ground with ZSM-5 having a mass ratio of 1:1, Cr2O3 and a Si / Al ratio of 100, and then molded by adding 20% ​​silica sol) with a volume ratio of 13:2 and a lower catalyst bed layer (molded by Cr2O3 tablets). The catalyst in the catalyst bed was pretreated with H2 at 400°C for 3h; the temperature of the upper catalyst bed was set to 320°C and the temperature of the lower catalyst bed was set to 300°C.

[0113] The results of carbon dioxide conversion, aromatics selectivity, and aromatics distribution are shown in Table 1.

[0114] Comparative Example 2

[0115] The method of Example 1 is as follows, except that

[0116] The temperatures of the catalyst upper bed, catalyst middle bed and catalyst lower bed were set to 320°C at the same time.

[0117] The results of carbon dioxide conversion, aromatics selectivity, and aromatics distribution are shown in Table 1.

[0118] Comparative Example 3

[0119] The method of Example 1 is followed, except that the raw gas A is fed alone, and other conditions are the same.

[0120] The results of carbon dioxide conversion, aromatics selectivity, and aromatics distribution are shown in Table 1.

[0121] Table 1

[0122]

[0123] As can be seen from the results in Table 1, the aromatics-containing streams prepared in Examples 1-9, in which the raw gases A and B of the present invention enter the reactor in a countercurrent manner and are contacted with a catalyst bed containing a metal oxide / molecular sieve, have a high CO2 conversion rate and a high aromatics selectivity, especially a high C9 aromatics selectivity (percentage). Examples 1-9 of the present invention and Comparative Examples 1-3 illustrate that the present invention employs more than three catalyst beds, a stepwise increase in the temperature of the catalyst bed except for the bottom layer, and a countercurrent introduction of the raw gas, which have a better effect on regulating the distribution of aromatics.

Claims

1. A method for preparing aromatic hydrocarbons from feed gas containing carbon dioxide and hydrogen, characterized in that: The method comprises: reacting a raw gas A containing carbon dioxide and hydrogen with a raw gas B containing carbon dioxide and hydrogen in countercurrent in a bed filled with at least n levels of catalyst to obtain a stream containing aromatic hydrocarbons; wherein n is an integer greater than or equal to 3; the catalyst in the catalyst bed comprises a metal oxide and a molecular sieve; along the flow direction of the feed gas A, the temperature of the catalyst bed from the first stage to the n-1 stage increases step by step, and the temperature of the catalyst bed of the nth stage is lower than the temperature of the catalyst bed of the n-1 stage; Mass ratio of metal oxide to molecular sieve in the catalyst bed from the 1st to the n-1th stage Decreasing step by step.

2. The method according to claim 1, wherein The difference in the mass ratio of metal oxide to molecular sieve in two adjacent catalyst beds from the 1st to the n-2nd stage 1:5 to 5:1; and / or The mass ratio of metal oxide to molecular sieve in the first stage catalyst bed is 1:5 to 5:1; and / or The metal oxide content in the n-1 stage catalyst bed is 0.

3. The method according to claim 2, wherein: The difference in the mass ratio of metal oxide to molecular sieve in the two adjacent catalyst beds from the 1st to the n-2nd stage 1:3 to 3:1; and / or The mass ratio of metal oxide to molecular sieve in the first stage catalyst bed is It is 1:3 to 3:

1.

4. The method according to claim 1 or 2, wherein: The temperature of each catalyst bed is 250-550°C.

5. The method according to claim 4, wherein In the catalyst beds of the first to n-1 stages, the temperature difference between two adjacent catalyst beds is 20-200°C; and / or The temperature difference between the nth stage catalyst bed and the n-1th stage catalyst bed is 20-200°C.

6. The method according to claim 5, wherein: The temperature difference between two adjacent catalyst beds in the first to n-1th stages is 50-150°C; and / or The temperature difference between the nth stage catalyst bed and the n-1th stage catalyst bed is 50-100°C.

7. The method according to claim 1 or 2, wherein: The volume ratio of the first-stage catalyst bed to the n-stage catalyst bed is 1:2 to 20:1; the volume ratio of two adjacent catalyst beds in the first to n-1-stage catalyst beds is 1:2 to 10:1; n is an integer from 3 to 10.

8. The method according to claim 7, wherein: The volume ratio of the first-stage catalyst bed to the n-stage catalyst bed is 3:1 to 10:1; the volume ratio of two adjacent catalyst beds in the first to n-1-stage catalyst beds is 1:1 to 5:1; n is an integer from 3 to 5.

9. The method according to claim 1 or 2, wherein: The total content of carbon dioxide and hydrogen in the feed gas A is 50-100% by volume, and the inert gas is supplemented to 100% by volume; and / or The total content of carbon dioxide and hydrogen in the raw gas B is 20-100% by volume, and the inert gas is supplemented to 100% by volume.

10. The method according to claim 9, wherein: The total content of carbon dioxide and hydrogen in the feed gas A is 80-100% by volume and the inert gas is supplemented to 100% by volume; and / or The total content of carbon dioxide and hydrogen in the raw gas B is 50-100% by volume, and the inert gas is supplemented to 100% by volume.

11. The method according to claim 1 or 2, wherein The molar ratio of hydrogen to carbon dioxide in raw gas B is not less than the molar ratio of hydrogen to carbon dioxide in raw gas A.

12. The method according to claim 11, wherein The molar ratio of hydrogen to carbon dioxide in the feed gas A is 0.5-6.0; and / or The molar ratio of hydrogen to carbon dioxide in the raw gas B is 0.5-6.

0.

13. The method according to claim 12, wherein The molar ratio of hydrogen to carbon dioxide in the feed gas A is 1.0-3.0; and / or The molar ratio of hydrogen to carbon dioxide in the raw gas B is 1.0-4.

0.

14. The method according to claim 9, wherein The raw gas B also includes an alkylating agent.

15. The method according to claim 14, wherein The molar ratio of the alkylating agent to the carbon dioxide in the raw gas B is 0.01-10 based on the provided alkyl group.

16. The method according to claim 15, wherein The molar ratio of the alkylating agent to the carbon dioxide in the raw gas B is 0.01-1 based on the provided alkyl group.

17. The method according to claim 15 or 16, wherein The alkylating agent is selected from one or more of methanol, dimethyl ether and light olefins.

18. The method according to claim 1 or 2, wherein: The metal elements in the metal oxide include one or more of Group IB metal elements, Group IIB metal elements, Group IIIB metal elements, Group IIIA metal elements, Group IVB metal elements, Group VIB metal elements and Group VIIB metal elements; and / or, The molecular sieve is a molecular sieve with a ten-membered ring structure or a twelve-membered ring structure.

19. The method according to claim 18, wherein The metal elements in the metal oxide include one or more of Zn, Y, Ga, In, Mn, Cu, Cr, La, Ce, Mo, Zr and Al; and / or The molecular sieve is selected from one or more of ZSM-5, ZSM-11, Silicalite-1, Silicalite-2, Hβ and HY.

20. The method according to claim 1 or 2, wherein: Before the contact reaction, the catalyst in the catalyst bed is pretreated in a reducing atmosphere.

21. The method according to claim 1 or 2, wherein The conditions for contact reaction include: The volumetric space velocity of feed gas A is higher than that of feed gas B; and / or, The reaction pressure is 1.0-8.0 MPa.

22. The method according to claim 21, wherein The ratio of the volume space velocity of the raw gas A to the raw gas B is 5:1 to 100:1; and / or The reaction pressure is 2.0-6.0MPa.

23. The method according to claim 22, wherein The ratio of the volume space velocity of the raw gas A to the raw gas B is 10:1 to 50:

1.

24. The method according to claim 22 or 23, wherein the volume space velocity of the feed gas A is 600-10000 mL g -1 h -1 .

Images