CN114262251A

CN114262251A - Process for improving methanol aromatization reaction performance

Info

Publication number: CN114262251A
Application number: CN202210010901.3A
Authority: CN
Inventors: 马晓迅; 代成义; 金润泽; 马科; 唐忠强
Original assignee: Northwest University
Current assignee: Northwest University
Priority date: 2022-01-05
Filing date: 2022-01-05
Publication date: 2022-04-01

Abstract

The invention discloses a process for improving the performance of methanol aromatization reaction, which comprises the steps of mixing and filling catalysts SAPO-34 and Zn/ZSM-5 into a reactor, introducing methanol from the top of the reactor, collecting products from the bottom of the reactor, and finishing the methanol aromatization reaction by controlling the mass ratio and the reaction temperature of the SAPO-34 and the Zn/ZSM-5. The invention obviously improves the selectivity of aromatic hydrocarbon in the aromatization of the methanol.

Description

Process for improving methanol aromatization reaction performance

Technical Field

The invention belongs to the technical field of energy chemical catalysts, and particularly relates to a process for improving the aromatization reaction performance of methanol.

Background

Aromatic hydrocarbon is an important organic reaction intermediate in the petroleum industry, and is widely applied to a plurality of industries such as medicine, war industry, materials, daily cosmetics and the like. At present, the main source of aromatic hydrocarbon still depends on the traditional processes such as catalytic reforming in petrochemical industry.

The current production of aromatics in the traditional petroleum route is more challenging. Gasification of coal as raw material to produce CO and H in the field of coal chemical industry₂The technology for synthesizing the methanol is mature day by day, the production of the methanol is seriously excessive in recent years, and the working rate of the methanol is always lower than 60 percent. Therefore, the methanol-to-aromatics (MTA) process using methanol as the raw material opens up a new process route with good development prospect for producing BTX from coal (or methanol) without depending on petroleum resources, not only supplements the shortage of aromatic hydrocarbon demand in the market, but also provides a way for methanol, thereby becoming a research hotspot of vast researchers and various large coal chemical enterprises. However, the industrialization of the MTA technology is restricted by the problems of low selectivity of aromatic hydrocarbon, poor stability and the like in the MTA technology caused by the generation of a large amount of alkane and the dynamic process of dehydrogenation-hydrogenation in the reaction process.

Light aromatic hydrocarbon (BTX) in aromatic hydrocarbon is an important petrochemical organic chemical raw material, and in the face of increasing aromatic hydrocarbon demand, a coal-based aromatic hydrocarbon production technology must be developed, and a non-petroleum sustainable development environment-friendly route is taken, so that under the background, in order to promote the development of the coal chemical industry and reduce the dependence on the petroleum route, the decision is made to start from methanol, the methanol industrial structure can be optimized, and the economic development can be pulled, and the method has great significance.

At present, HZSM-5 catalyst is mostly adopted in the process of preparing aromatic hydrocarbon from methanol, but the key point is that high aromatic hydrocarbon selectivity is obtained and side reactions are more. On the basis of the existing research, a small fixed bed is selected, a widely used ZSM-5 catalyst with adjustable acidity and pore channel shape selectivity is selected, and high aromatic selectivity is expected to be obtained after metal modification and adjustment processes.

HZSM-5 also has a problem in catalyzing the reaction of preparing aromatic hydrocarbon from methanol, namely the selectivity of the aromatic hydrocarbon is generally low. Because the acid structure of the HZSM-5 molecular sieve is complex, and the acid type and the acid strength are greatly different, a plurality of interrelated complex reactions can be generated in the MTA process, a large amount of non-aromatic hydrocarbon products are generated, and the aromatic hydrocarbon selectivity is reduced. Aiming at the problem, a dehydrogenated metal Zn species is usually adopted to modify HZSM-5 to obtain the bifunctional ZSM-5 catalyst, which is beneficial to enhancing alkane dehydrogenation reaction and alkene aromatization reaction and improving arene selectivity. However, the aromatic selectivity of Zn/ZSM-5 bifunctional catalyst for MTA reaction is still low, and catalyst deactivation is further accelerated after loading Zn metal. In summary, obtaining higher aromatics selectivity over a single catalyst remains a major challenge.

Disclosure of Invention

The invention aims to provide a process for improving the aromatization reaction performance of methanol, which overcomes the defects in the prior art. The invention obviously improves the selectivity of aromatic hydrocarbon in the aromatization of the methanol.

In order to achieve the purpose, the invention adopts the following technical scheme:

a process for improving the performance of methanol aromatization reaction comprises the steps of mixing and filling catalysts SAPO-34 and Zn/ZSM-5 into a reactor, introducing methanol from the top of the reactor, collecting products from the bottom of the reactor, and finishing the methanol aromatization reaction by controlling the mass ratio and the reaction temperature of the SAPO-34 and the Zn/ZSM-5.

Further, the mixing mode of the catalyst SAPO-34 and Zn/ZSM-5 is specifically as follows: the SAPO-34 and Zn/ZSM-5 catalysts are filled in the form of upper and lower beds.

Further, the mixing mode of the catalyst SAPO-34 and Zn/ZSM-5 is specifically as follows: the SAPO-34 catalyst and Zn/ZSM-5 catalyst are mixed and packed in a tablet form.

Further, the mixing mode of the catalyst SAPO-34 and Zn/ZSM-5 is specifically as follows: the SAPO-34 catalyst and Zn/ZSM-5 catalyst are packed in a form of tabletting and mixing.

Further, the mass ratio of the catalyst SAPO-34 to the Zn/ZSM-5 is 9:1-1: 9.

Further, the reaction temperature is 673K-723K.

Further, the space velocity of the methanol is 1h^-1。

Further, the catalyst SAPO-34 has a silicon to aluminum ratio of 0.07, 0.1, or 0.15.

Further, the catalyst Zn/ZSM-5 has a silica to alumina ratio of 23, 30 or 40.

Compared with the prior art, the invention has the following beneficial technical effects:

the SAPO-34 and the Zn/ZSM-5 are filled in different modes, so that the generated low-carbon olefin is used as an intermediate for methanol aromatization to promote the reaction, thereby achieving the purpose of improving the selectivity of aromatic hydrocarbon.

The invention adopts two different catalysts which are connected in series to participate in the aromatization reaction of preparing the low-carbon olefin and the low-carbon olefin from the methanol respectively by means of modulating the catalyst structure, and prepares the aromatic hydrocarbon by two-step coupling, wherein in the reaction process, the methanol is firstly converted into C by SAPO-34₂ ^＝-C₃ ^＝The main intermediate product, and then further converting the olefin into the aromatic hydrocarbon through polymerization, cycloaddition, hydrogen transfer and the like. For the two-step conversion process described above, methanol is converted to C primarily at the upper SAPO-34₂ ^＝-C₃ ^＝And then these lower olefins are converted to aromatics on the underlying Zn/ZSM-5. Compared with the catalytic performance of the single Zn/ZSM-5 filling layer, the aromatic selectivity and the BTX selectivity of the upper and lower layers of the SAPO-34 filling layer and the Zn/ZSM-5 filling layer are respectively increased from 61.9 percent, 32 percent to 76.5 percent and 50.3 percent. This is due to the high and low olefin selectivity of the upstream catalyst promoting the aromatic hydrocarbon cycle process in the methanol aromatization process, reducing the difficulty of catalyst structure adjustment, and promoting the production of light aromatic hydrocarbons such as BTX.

Drawings

FIG. 1 is a schematic diagram of different mixing forms of SAPO-34 and Zn/ZSM-5 catalysts, wherein (a) shows that SAPO-34 is filled alone, (b) shows that SAPO-34 and Zn/ZSM-5 are filled in a form of mixed tablets, (c) shows that SAPO-34 and Zn/ZSM-5 are filled in a form of mixed tablets after tabletting, and (d) shows that SAPO-34 and Zn/ZSM-5 are filled in a form of upper and lower beds; (e) represents the Zn/ZSM-5 loading alone;

FIG. 2 is a diagram showing the selectivity of aromatics in the methanol-to-aromatics reaction in which catalysts SAPO-34 and Zn/ZSM-5 are mixed differently;

FIG. 3 is an XRD pattern of Zn/ZSM-5 and SAPO-34 of varying silica to alumina ratios, wherein (a) SP 0.07; (b) SP 0.1; (c) SP 0.15; (d) ZnZ23, respectively; (e) ZnZ30, respectively; (f) ZnZ40, respectively;

FIG. 4 is a diagram showing the effect of upper and lower layer packing of SAPO-34 and Zn/ZSM-5, wherein (a) the influence of upper and lower layer packing of Zn/ZSM-5 and SAPO-34 with different Si/Al ratios on the reaction performance is shown, and (b) the product distribution, BTX selectivity and aromatic hydrocarbon selectivity of Zn/ZSM-5 and SAPO-34 at different temperatures are shown.

Detailed Description

The invention is further described below.

A process for improving methanol aromatization reaction performance is characterized in that catalysts SAPO-34 and Zn/ZSM-5 are mixed and filled in a reactor, as shown in figure 1, the mixing mode is as follows: filling catalysts SAPO-34 and Zn/ZSM-5 in the form of an upper bed layer and a lower bed layer (figure 1d), filling the catalysts SAPO-34 and Zn/ZSM-5 in the form of mixing and tabletting (figure 1b), or filling the catalysts SAPO-34 and Zn/ZSM-5 in the form of mixing and tabletting (figure 1c), introducing methanol from the top of a reactor, collecting a product from the bottom of the reactor, controlling the mass ratio of the catalysts SAPO-34 to Zn/ZSM-5 to be 9:1-1:9, controlling the reaction temperature to be 673K-723K, and controlling the space velocity of the methanol to be 1h^-1The catalysts SAPO-34 are respectively marked as SP0.07, SP0.1 and SP0.15, and the catalysts Zn/ZSM-5 are respectively marked as ZnZ23, ZnZ30 and ZnZ40, so that the methanol aromatization reaction is completed.

The preparation method of the catalyst comprises the following steps:

1. preparation of parent catalyst

A certain amount of TPABr was weighed at room temperature and added to a beaker containing silica sol, and the solution was stirred for 35 minutes. After the solution had assumed a homogeneous stable state, a solution of ethylamine (65 wt%) was added dropwise and stirred for one hour. After the stirring, the aqueous solution of aluminum nitrate was added and stirred for 30 minutes, and after the seed crystal solution was added dropwise, the stirring was continued for 1 hour. The resulting gel was transferred to an autoclave lined with polytetrafluoroethylene and crystallized at 170 ℃ for 72 hours. After the mother liquor is cooled to normal temperature, the mother liquor is centrifuged, deionized water is used for 3 to 4 times, and then the mother liquor is dried for 12 hours at 80 ℃, ground and roasted for 6 hours at 550 ℃. The mixture ratio: 1SiO₂:yAl(NO₃)₃·9H₂O:0.15TPABr：1EA:17H₂O1% seed crystal (y is 0.167, 0.0125, 0.0217), namely, the silica-alumina ratio of the prepared ZSM-5 molecular sieve is 23, 30 and 40 respectively.

Uniformly mixing aluminum isopropoxide, silica sol and tetraethyl ammonium hydroxide in a certain sequence, violently stirring for 2.5h, adding a proper amount of phosphoric acid into the mixed solution, continuously stirring for 30min to obtain an initial gel mixture, transferring the initial gel mixture into a 100ml kettle, and crystallizing for 3d at 160 ℃. After the crystallization is finished, the mixture is quenched and the supernatant liquid is filtered out, and the obtained product is centrifuged to be neutral and is roasted for 8 hours at 550 ℃ in a muffle furnace. The mixture ratio: 1Al₂O₃4P₂O₅:xSiO₂:4TEAOH:147H₂O (x ═ 0.14, 2, 3), i.e., SAPO-34 molecular sieve preparation, silica to alumina ratios were 0.07, 1, 1.5, respectively. Hereinafter, the parent SAPO-34 of different Si/Al ratios are respectively SP0.07, SP0.1 and SP 0.15.

Preparation method of Zn/ZSM-5 catalyst

The ZSM-5 prepared by the method is subjected to Zn modification by adopting an isometric impregnation method, and the specific operation method for the Zn loading of 3 wt% comprises the following steps: soaking the ZSM-5 molecular sieve into a certain amount of zinc nitrate solution (3 wt% of Zn is soaked in the solution) with the same water absorption amount as the ZSM-5 molecular sieve, pouring the catalyst into the solution, putting the solution into an ultrasonic cleaner, uniformly mixing the solution, and standing for 1-2 h. And then putting the mixture into an oven at 80 ℃ for drying for 8h, and then putting the mixture into a muffle furnace for roasting at 550 ℃ for 4h to obtain the Zn/ZSM-5 molecular sieve. Hereinafter, the ZSM-5 with different Si/Al ratios after Zn modification are respectively ZnZ23, ZnZ30 and ZnZ 40.

The present invention will be described in detail with reference to examples. It should be noted that the embodiments and features of the embodiments in the present application may be combined with each other without conflict.

The following detailed description is illustrative of the embodiments and is intended to provide further details of the invention. Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of exemplary embodiments according to the invention.

Comparative example 1

Filling a catalyst SAPO-34 into a reactor, introducing methanol from the top of the reactor as shown in figure 1a, collecting a product from the bottom of the reactor, wherein the reaction temperature is 698K, and the space velocity of the methanol is 1h^-1And the SAPO-34 catalyst is SP0.07, thus completing the aromatization reaction of the methanol.

Comparative example 2

Filling a catalyst Zn/ZSM-5 into a reactor, introducing methanol from the top of the reactor as shown in figure 1e, collecting a product from the bottom of the reactor, wherein the reaction temperature is 698K, and the space velocity of the methanol is 1h^-1And the catalyst Zn/ZSM-5 is ZnZ30, and the methanol aromatization reaction is completed.

Example 1

Mixing and filling the catalysts SAPO-34 and Zn/ZSM-5 into a reactor, filling the catalysts SAPO-34 and Zn/ZSM-5 in a form of mixed tablets as shown in figure 1b, introducing methanol from the top of the reactor, collecting products from the bottom of the reactor, controlling the mass ratio of the catalysts SAPO-34 to Zn/ZSM-5 to be 5:5, performing the mixed tablets as the filling mode, controlling the reaction temperature to be 698K and controlling the space velocity of the methanol to be 1h^-1The catalyst SAPO-34 is SP0.07, and the catalyst Zn/ZSM-5 is ZnZ30, completing the methanol aromatization reaction.

Example 2

Mixing and filling the catalysts SAPO-34 and Zn/ZSM-5 into a reactor, filling the catalysts SAPO-34 and Zn/ZSM-5 in a mixed form after tabletting as shown in figure 1c, introducing methanol from the top of the reactor, collecting a product from the bottom of the reactor, controlling the mass ratio of the catalysts SAPO-34 and Zn/ZSM-5 to be 5:5, mixing after tabletting in a filling mode, controlling the reaction temperature to be 698K and controlling the space velocity of the methanol to be 1h^-1The catalyst SAPO-34 is SP0.1, and the catalyst Zn/ZSM-5 is ZnZ30, thus completing the methanol aromatization reaction.

Example 3

Mixing and filling the catalysts SAPO-34 and Zn/ZSM-5 into a reactor, filling the catalysts SAPO-34 and Zn/ZSM-5 in the form of an upper bed layer and a lower bed layer as shown in figure 1d, introducing methanol from the top of the reactor, collecting products from the bottom of the reactor, controlling the mass ratio of the catalysts SAPO-34 to the Zn/ZSM-5 to be 5:5, layering the filling mode from top to bottom, and the reaction temperature to be 698K,the space velocity of the methanol is 1h^-1The catalyst SAPO-34 is SP0.15, and the catalyst Zn/ZSM-5 is ZnZ40, thus completing the methanol aromatization reaction.

Example 4

Mixing and filling the catalysts SAPO-34 and Zn/ZSM-5 into a reactor, filling the catalysts SAPO-34 and Zn/ZSM-5 in the form of an upper bed layer and a lower bed layer as shown in figure 1d, introducing methanol from the top of the reactor, collecting products from the bottom of the reactor, controlling the mass ratio of the catalysts SAPO-34 to Zn/ZSM-5 to be 1:9, the reaction temperature to be 698K ℃, and the space velocity of the methanol to be 1h^-1The catalyst SAPO-34 is SP0.07, and the catalyst Zn/ZSM-5 is ZnZ23, completing the methanol aromatization reaction.

Example 5

Mixing and filling the catalysts SAPO-34 and Zn/ZSM-5 into a reactor, filling the catalysts SAPO-34 and Zn/ZSM-5 in the form of an upper bed layer and a lower bed layer as shown in figure 1d, introducing methanol from the top of the reactor, collecting products from the bottom of the reactor, controlling the mass ratio of the catalysts SAPO-34 to Zn/ZSM-5 to be 1:9, the reaction temperature to be 698K and the space velocity of the methanol to be 1h^-1The catalyst SAPO-34 is SP0.07, and the catalyst Zn/ZSM-5 is ZnZ40, completing the methanol aromatization reaction.

Example 6

Mixing and filling the catalysts SAPO-34 and Zn/ZSM-5 into a reactor, filling the catalysts SAPO-34 and Zn/ZSM-5 in the form of an upper bed layer and a lower bed layer as shown in figure 1d, introducing methanol from the top of the reactor, collecting products from the bottom of the reactor, controlling the mass ratio of the catalysts SAPO-34 to Zn/ZSM-5 to be 1:9, the reaction temperature to be 698K ℃, and the space velocity of the methanol to be 1h^-1The catalyst SAPO-34 is SP0.1, and the catalyst Zn/ZSM-5 is ZnZ40, thus completing the methanol aromatization reaction.

Example 7

Mixing and filling the catalysts SAPO-34 and Zn/ZSM-5 into a reactor, filling the catalysts SAPO-34 and Zn/ZSM-5 in the form of an upper bed layer and a lower bed layer as shown in figure 1d, introducing methanol from the top of the reactor, collecting products from the bottom of the reactor, controlling the mass ratio of the catalysts SAPO-34 to Zn/ZSM-5 to be 1:9, the reaction temperature to be 698K and the space velocity of the methanol to be 1h^-1SAPO-34 as catalyst SP0.15 and Zn as catalystthe/ZSM-5 is ZnZ40, and the methanol aromatization reaction is completed.

Example 8

Mixing and filling the catalysts SAPO-34 and Zn/ZSM-5 into a reactor, filling the catalysts SAPO-34 and Zn/ZSM-5 in the form of an upper bed layer and a lower bed layer as shown in figure 1d, introducing methanol from the top of the reactor, collecting products from the bottom of the reactor, controlling the mass ratio of the catalysts SAPO-34 to Zn/ZSM-5 to be 1:9, the reaction temperature to be 673K and the space velocity of the methanol to be 1h^-1The catalyst SAPO-34 is SP0.07, and the catalyst Zn/ZSM-5 is ZnZ30, completing the methanol aromatization reaction.

Example 9

Mixing and filling the catalysts SAPO-34 and Zn/ZSM-5 into a reactor, filling the catalysts SAPO-34 and Zn/ZSM-5 in the form of an upper bed layer and a lower bed layer as shown in figure 1d, introducing methanol from the top of the reactor, collecting products from the bottom of the reactor, controlling the mass ratio of the catalysts SAPO-34 to Zn/ZSM-5 to be 1:9, the reaction temperature to be 723K and the space velocity of the methanol to be 1h^-1The catalyst SAPO-34 is SP0.07, and the catalyst Zn/ZSM-5 is ZnZ30, completing the methanol aromatization reaction.

SAPO-34 and Zn/ZSM-5 were loaded in different ways (FIG. 1) on a fixed bed reactor and MTA reaction performance was evaluated. The performance of the catalyst obtained is shown in figure 2. When SAPO-34 is singly filled (as shown in FIG. 1(a)), no large-size substances such as aromatic hydrocarbon are generated in the product due to the limitation of the pore channels of SAPO-34, and C₂ ^＝-C₃ ^＝The selectivity of (A) is up to 75.2%. Compared with the single-filled SAPO-34, when Zn/ZSM-5 is mixed, liquid-phase substances such as aromatic hydrocarbon and the like appear in the product. And the layered filling has higher BTX selectivity and aromatic selectivity, which are respectively improved from 30.6 percent to 50.3 percent and 64.5 percent to 76.5 percent. The reason is that when the distance between the active centers of the two catalysts is gradually increased, the generated intermediate products such as low-carbon olefin and the like are further converted, the diffusion is convenient, the orifice of the catalyst is prevented from being blocked by the generated macromolecular products, and the selectivity of the catalyst is greatly improved. And the selectivity of the low-carbon olefin of the layered filling mode is reduced compared with that of the two physical mixed filling modes, which further explains the generation of the SAPO-34 catalystThe low-carbon olefin can pass through the lower Zn/ZSM-5 catalytic bed layer to be further converted into aromatic hydrocarbon. The BTX selectivity is increased probably because the low-carbon olefin enters the lower Zn/ZSM-5 catalytic bed layer to inhibit the 'aromatic hydrocarbon circulation', thereby inhibiting the generation of heavy aromatic hydrocarbon (C)₉ ⁺Aromatic hydrocarbons) are produced.

As can be seen from FIG. 4(a), under the condition that the Si/Al ratio of the SAPO-34 molecular sieve is not changed, the Si/Al ratio of the ZSM-5 molecular sieve is gradually increased, the selectivity of aromatic hydrocarbon is reduced, and low-carbon olefin and C are adopted₉ ⁺The selectivity is increased. Under the condition that the ZSM-5 silica alumina ratio is not changed, the silica alumina ratio of SAPO-34 is gradually increased, the selectivity of aromatic hydrocarbon is gradually increased, and the low-carbon olefin and C₉ ⁺The selectivity of (a) gradually decreases. This further illustrates that the consumption of lower olefins promotes aromatics recycle such that aromatics selectivity increases. The ZSM-5 molecular sieve catalyst with low silica-alumina ratio has higher acidity, more strong acid sites and outstanding aromatization and cracking capability, so that more aromatic hydrocarbon is generated in the methanol aromatization process on the molecular sieve with low silica-alumina ratio, and the BTX content in the aromatic hydrocarbon is also higher. However, the ZSM-5 molecular sieve catalyst with higher silica-alumina ratio has lower numbers of strong acid sites and weak acid sites, which affects the reactions of light olefin polymerization, aromatization, isomerization and the like, resulting in C in the product₉ ⁺The product is gradually increased. The amount of the B acid and the amount of the medium-strength acid of the SAPO-34 are gradually increased along with the increase of the ratio of silicon to aluminum. Resulting in a reduced degree of deep alkylation of the xylenes, C₉ ⁺Selectivity gradually decreased and BTX selectivity increased.

As can be seen from FIG. 4(b), the selectivity to aromatics and BTX in the product also increased with increasing temperature, C₉ ⁺The selectivity of the aromatic hydrocarbon is also obviously improved, and when the temperature reaches 723K, the selectivity of the aromatic hydrocarbon and the aromatic hydrocarbon is reduced to a certain extent. This is probably because the aromatization activity of the olefin is gradually increased along with the increase of the temperature, which is more favorable for the cyclization, polymerization, isomerization and other reactions of the olefin, thereby improving the selectivity of the aromatic hydrocarbon to a certain extent. However, with further increase in the reaction temperature, the alkylation reaction activity of light aromatic hydrocarbons such as benzene and toluene is also increased to some extent, and the reaction temperature is increased more toward heavy aromatic hydrocarbons such as trimethylbenzeneConversion of hydrocarbons thereby increasing C₉ ⁺Selectivity of aromatic hydrocarbon. It is worth mentioning that as the temperature increases, the butene selectivity gradually decreases. While the selectivity to ethylene gradually increases. This is probably because as the temperature increases, long carbon chains are broken down to produce smaller molecules.

In conclusion, a series of comparative experiments such as the filling mode, the filling ratio and the like of the two catalysts are considered, and the result shows that the aromatization performance of the SAPO-34 and the Zn/ZSM-5 is optimal through upper-lower layered filling. Methanol is mainly converted into light olefins, particularly ethylene and propylene, by the upper SAPO-34 catalyst. These lower olefins are then further converted to aromatics on the underlying Zn/ZSM-5 as intermediates in the methanol aromatization reaction. The reason is that the aromatic hydrocarbon preparation by two-step concerted catalysis of methanol-to-olefin and olefin aromatization can reduce the aromatic hydrocarbon circulation reaction depth and promote the formation of light aromatic hydrocarbons such as BTX (benzene, toluene and xylene). Finally, when SAPO-34 and Zn/ZSM-5 are coupled for catalysis, the BTX selectivity in aromatic hydrocarbon reaches 50.3 percent, which is far higher than 32 percent of one-step conversion. The SAPO-34 prepared by the invention is used as an olefin catalyst and a low-silica-alumina-ratio Zn/ZSM-5 aromatization catalyst to respectively meet the requirements of low-carbon hydrocarbon preparation from methanol and low-carbon hydrocarbon aromatization reaction on the catalysts, and the two catalysts are physically mixed according to different mass ratios to perform methanol-to-aromatic hydrocarbon reaction evaluation. By matching the two catalysts to different degrees, an efficient coupling of the two-step reaction is achieved, which can be considered as an advantageous route for the production of BTX due to its feasibility and economy.

In addition, the filling mass ratio, the temperature and other conditions of the catalysts SAPO-34 and Zn/ZSM-5 are respectively adjusted, the coupling efficiency of the two corresponding reactions is optimized, and the selectivity of aromatic hydrocarbon is improved. When the weight ratio of the upper bed layer to the lower bed layer is reduced from 9:1 to 1:9, the selectivity of the aromatic hydrocarbon is improved from 29.7 percent to 76.5 percent, and the catalytic life is also improved.

It will be appreciated by those skilled in the art that the invention may be embodied in other specific forms without departing from the spirit or essential characteristics thereof. The embodiments disclosed above are therefore to be considered in all respects as illustrative and not restrictive. All changes which come within the scope of or equivalence to the invention are intended to be embraced therein.

Claims

1. A process for improving methanol aromatization reaction performance is characterized in that catalysts SAPO-34 and Zn/ZSM-5 are mixed and filled into a reactor, methanol is introduced from the top of the reactor, products are collected from the bottom of the reactor, and the methanol aromatization reaction is completed by controlling the mass ratio and the reaction temperature of the SAPO-34 and the Zn/ZSM-5.

2. The process for improving the performance of the methanol aromatization reaction according to claim 1, wherein the mixing mode of the catalyst SAPO-34 and Zn/ZSM-5 is specifically as follows: the SAPO-34 and Zn/ZSM-5 catalysts are filled in the form of upper and lower beds.

3. The process for improving the performance of the methanol aromatization reaction according to claim 1, wherein the mixing mode of the catalyst SAPO-34 and Zn/ZSM-5 is specifically as follows: the SAPO-34 catalyst and Zn/ZSM-5 catalyst are mixed and packed in a tablet form.

4. The process for improving the performance of the methanol aromatization reaction according to claim 1, wherein the mixing mode of the catalyst SAPO-34 and Zn/ZSM-5 is specifically as follows: the SAPO-34 catalyst and Zn/ZSM-5 catalyst are packed in a form of tabletting and mixing.

5. The process for improving the performance of the methanol aromatization reaction according to claim 1, wherein the mass ratio of the catalyst SAPO-34 to Zn/ZSM-5 is 9:1-1: 9.

6. The process for improving the performance of a methanol aromatization reaction according to claim 1 wherein the reaction temperature is 673K to 723K.

7. The process of claim 1, wherein the space velocity of methanol is 1h^-1。

8. The process of claim 1, wherein the catalyst SAPO-34 has a silica to alumina ratio of 0.07, 0.1 or 0.15.

9. The process for improving the performance of a methanol aromatization reaction according to claim 1, wherein the catalyst Zn/ZSM-5 has a silica to alumina ratio of 23, 30 or 40.