CN109608301B

CN109608301B - Method for preparing butylene and butadiene through catalytic dehydrogenation of butane

Info

Publication number: CN109608301B
Application number: CN201710964985.3A
Authority: CN
Inventors: 张桥; 徐勇; 曹暮寒; 刘其鹏; 杨迪
Original assignee: Suzhou University
Current assignee: Suzhou University
Priority date: 2017-10-17
Filing date: 2017-10-17
Publication date: 2021-10-19
Anticipated expiration: 2037-10-17
Also published as: CN109608301A

Abstract

The invention provides a method for preparing butylene and butadiene by butane catalytic dehydrogenation, which uses a double-active-component composite catalyst containing zirconium and gallium, butane is subjected to high-efficiency dehydrogenation, the selectivity of butadiene in a product reaches 17 percent, the selectivity of total butylene reaches 81.5 percent, and the catalyst shows good stability and reproducibility at high temperature.

Description

Method for preparing butylene and butadiene through catalytic dehydrogenation of butane

Technical Field

The invention relates to a method for preparing butylene and butadiene, in particular to a method for preparing butylene and butadiene by catalytic dehydrogenation of butane.

Background

Butene is a petrochemical basic raw material, has the second place to ethylene and propylene in petrochemical olefin raw materials, and is an important monomer for synthesizing rubber and high polymer materials. Generally, butenes are mainly in the form of several isomers, e.g., n-butene (1-butene), isobutene, cis-dibutene and trans-dibutene. N-butenes are used primarily to make polymers and copolymers of methyl ethyl ketone, sec-butyl alcohol, butylene oxide, and butylenes. Isobutene is mainly used for manufacturing butyl rubber, polyisobutylene rubber and various plastics. Generally, 1-butene and 2-butene need not be separated and can be chemically processed together to produce many important basic organic chemicals, such as sec-butanol hydration to produce methyl ethyl ketone, butadiene by oxidative dehydrogenation, maleic anhydride by catalytic oxidation, and acetic acid. Further, butene can be used as a raw material for producing butadiene. Butadiene is a basic raw material in petrochemical industry, has the second place to ethylene and propylene in petrochemical olefin raw materials, and is an important monomer for synthesizing rubber and high polymer materials. Commercial butene production is obtained mainly by separation of the carbon four fraction. The quality of the butenes in the carbon four fractions from different sources varies. With the rapid development of the petroleum industry in China, the price of petroleum is high, the generation cost of petroleum-based products is too high, the capacity of butylene is far behind the actual demand, the situation of shortage of butylene supply and demand is more serious, and the development of national economy is restricted to a great extent.

Indeed, since the last century, scientists have endeavored to develop new processes for the preparation of butenes, such as the preparation of the corresponding butenes by dehydrogenation starting from n-butane, and have already achieved industrialization. In recent years, with the continuous exploration of shale gas, the total amount of shale gas which can be produced worldwide is huge. The relevant data show that: the total amount of globally producible shale gas is up to 207 cubic meters, wherein the storage amount of China is the first in the world, and the total amount is up to 32 billion cubic meters. The main components of the shale gas are methane, ethane, propane and butane, and the low-carbon alkanes can be further synthesized into other chemical intermediates by means of oxidative coupling, so that abundant and cheap raw materials are provided for modern industries. Processes for producing butenes from butane are of greater interest. Two process routes are currently popular: direct dehydrogenation and oxidative dehydrogenation. Although oxidative dehydrogenation can slow down the formation of carbon deposit to a certain extent, the introduced oxidant is easy to generate carbon monoxide and carbon dioxide, so that the selectivity of butene is low. The direct dehydrogenation can effectively avoid the generation of other oxygen-containing products, and the selectivity of the olefin can reach more than 95 percent. While direct dehydrogenation often requires higher temperatures, which can lead to over-dehydrogenation of butanes and even chain scission to small molecular hydrocarbons, C-H bonds and C-C selectivity activity are often achieved through catalyst control. In addition, the carbon deposit formed can be achieved by catalyst regeneration. The direct dehydrogenation of butane to butene is therefore widely favored and the process has been carried out industrially.

The butane dehydrogenation catalysts currently used are several: (1) pt-based catalysts, noble metal catalysts, play a crucial role in dehydrogenation reactions, but are costly. The practical application is UOP company and Philips oil company, which select Pt as the active component of the catalyst, and improve the stability of the catalyst by adding an auxiliary agent and a carrier. The well-known auxiliary agent is Sn, and the catalyst which is commercialized at present is Pt-Sn-Al2O 3; (2) a V-based catalyst, which is typically supported on alumina or silica with vanadium oxide; (3) a Cr-based catalyst. Cr-based catalysts are another important non-metallic catalyst that is currently commercialized by Catofin. Although there are currently few reports of direct dehydrogenation catalysts, butane dehydrogenation still faces a number of problems and challenges. For example, thermodynamically, direct dehydrogenation is a strongly endothermic reaction that needs to be carried out at high temperatures. High temperatures tend to cause the catalyst to sinter and deactivate, thus requiring high stability of the catalyst. On the other hand, high temperatures tend to cause excessive dehydrogenation of butane to form carbon deposits, and therefore, the design of catalysts for selective dehydrogenation is also more demanding. In the case of the current industrial catalyst, the Pt catalyst is easy to deposit carbon, and although the carbon deposit can be burnt out by high-temperature regeneration, the Pt is easy to sinter and inactivate by high temperature. Although Sn addition has been reported to be effective in preventing Pt sintering, the regeneration process requires chlorination, which has a corrosive effect on equipment. Similar problems exist with Cr-based catalysts, where Cr migrates into the supported alumina at high temperatures causing loss of active components. On the other hand, the use of Cr also causes environmental pollution.

In conclusion, the development of a novel catalyst is a key step in the realization of the dehydrogenation of butane to olefins. The ideal catalyst should have excellent C-H activation performance and also be able to transfer intermediate products quickly to avoid over dehydrogenation and even chain scission; in addition, the catalyst should have excellent high temperature sintering resistance so that activity is maintained during cyclic regeneration; but also the development of non-noble metal-based, environmentally friendly catalysts should be emphasized to represent greater industrial value.

Disclosure of Invention

In view of the above problems in the prior art, the present invention aims to provide a method for preparing butylene and butadiene by catalytic dehydrogenation of butane, which realizes high conversion efficiency of butane.

In order to solve the problems, the technical scheme of the invention is as follows:

a method for preparing butylene and butadiene by butane catalytic dehydrogenation comprises the steps of carrying out dehydrogenation reaction on butane in the presence of a dehydrogenation catalyst, and separating butylene and butadiene from the obtained dehydrogenation product; the dehydrogenation catalyst comprises one or both of zirconium and gallium as active components.

Further, the active component in the dehydrogenation catalyst accounts for 1-10% of the total mass of the catalyst.

Preferably, the active component in the dehydrogenation catalyst accounts for 3-5% of the total mass of the catalyst.

Preferably, the active components in the dehydrogenation catalyst are zirconium and gallium, and the mass ratio of zirconium to gallium is 0.1-10.

Preferably, the mass ratio of zirconium to gallium in the active component in the dehydrogenation catalyst is 0.2 to 5.

The dehydrogenation catalyst comprises active components of zirconium and gallium, and is a double-active-component composite catalyst. The composite catalyst is based on non-noble metal zirconium and gallium, and realizes efficient dehydrogenation of butane through the synergistic effect of zirconium and gallium. The selective activation of C-H bond and C-C is realized by regulating and controlling the interface of the composite catalyst, thereby improving the selectivity of the butene.

The zirconium oxide and the gallium oxide not only have excellent thermal stability, but also can generate a large number of oxygen vacancies under hydrogen treatment, and can effectively promote C-H bond activation.

The above active component exists in the form of metal or metal oxide, and can be used alone as dehydrogenation catalyst, or can be supported on a carrier, and the carrier is not particularly limited, and preferably a silica-alumina composite carrier, for example, ZSM series molecular sieves, MCM series molecular sieves, beta-zeolite, etc., is used. The active component of the dehydrogenation catalyst in the supported catalyst accounts for 1 to 10%, preferably 3 to 5%, particularly preferably 4.5% of the total mass of the catalyst.

The above dehydrogenation catalysts can be prepared according to various methods known in the art, for example according to one embodiment of the present invention, the dehydrogenation catalyst is prepared as follows:

1) weighing a certain amount of soluble salts of zirconium and gallium and preparing into a mixed solution;

2) soaking the mixed solution on a silicon-aluminum composite carrier in the same volume;

3) after dipping, aging, drying and calcining at high temperature to obtain catalyst solid powder;

4) passing the solid catalyst powder through a gas-liquid separator₂/N₂And (5) performing high-temperature activation treatment on the mixed gas.

According to one embodiment of the present invention, the reaction conditions for preparing butene and butadiene by catalytic dehydrogenation of butane are as follows: the reaction temperature is 500-750 ℃, the reaction pressure is 0-0.3Mpa, and the gas hourly volume space velocity is 20-300h^-1. The butane is co-fed with hydrogen, wherein the molar ratio of hydrogen to butane is from 0.1 to 10.

Inert gases may also be used to dilute the hydrogen and butane concentrations during the catalytic dehydrogenation reaction to slow the temperature rise during the reaction. The inert gas is used for controlling the reaction temperature within 500-750 ℃, and the inert gas can be one or more of nitrogen, helium and argon.

In the present invention, the dehydrogenation product contains the components below C3 and C4. The C4 component contains primarily butenes (including 1-butene, 2-butene, and isobutene), butadiene, and unreacted butanes. The n-butenes and butadiene can be separated from the dehydrogenation product in the present invention by methods well known to those skilled in the art.

The invention has the following advantages:

1) non-noble metal zirconium and gallium are used as active components of the catalyst, so that the catalyst is environment-friendly, low in cost and high in industrial value and application prospect.

2) The efficient dehydrogenation of butane is realized through the synergistic effect of zirconium and gallium, the selectivity of butadiene in the product reaches about 17%, and the selectivity of total butylene reaches 81.5%.

3) The catalyst exhibits good stability and regenerability at high temperatures.

Drawings

FIG. 1 is an X-ray diffraction pattern of catalysts of varying active component content provided by examples of the present invention;

FIG. 2 is a graph of the conversion and selectivity of butane in the dehydrogenation of butane using catalysts of varying active component content according to the examples provided herein;

FIG. 3 is a product distribution diagram of the catalytic butane dehydrogenation of catalysts with different active component contents provided by the embodiment of the invention;

Detailed Description

The technical solutions in the embodiments of the present invention are clearly and completely described below, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments. All other embodiments, which can be obtained by a person skilled in the art without any inventive step based on the embodiments of the present invention, are within the scope of the present invention.

Example 1

Weighing a certain amount of zirconium nitrate, preparing a solution, and soaking the solution on the silicon-aluminum composite carrier in an equal volume. After dipping, aging for 1 hour, then placing the product in a baking oven at 100 ℃ overnight for drying, and roasting the obtained catalyst at high temperature of 750 ℃ for 2 hours to obtain the catalyst cat 1.

The mass fraction of zirconium in the catalyst obtained in this example was 4.47%, the specific surface area, pore volume, and pore diameter of the catalyst are shown in table 1, and the X-ray diffraction pattern is shown in fig. 1.

Example 2

According to the mass ratio of metal zirconium to metal gallium of 3.5:1, a certain amount of zirconium and gallium precursor zirconium nitrate and gallium nitrate are weighed and prepared into a mixed solution, and then the mixed solution is dipped on a silicon-aluminum composite carrier in an equal volume. After dipping, aging for 1 hour, then placing the product in a baking oven at 100 ℃ overnight for drying, and roasting the obtained catalyst at high temperature of 750 ℃ for 2 hours to obtain the catalyst cat 2.

The mass fraction of zirconium and the mass fraction of gallium in the catalyst obtained in this example were 3.53% and 0.81%, respectively. The specific surface area, pore volume and pore diameter of the catalyst are shown in Table 1, and the X-ray diffraction pattern is shown in FIG. 1.

Example 3

According to the mass ratio of metal zirconium to metal gallium of 2:2.5, a certain amount of zirconium and gallium precursor zirconium nitrate and gallium nitrate are weighed and prepared into a mixed solution, and then the mixed solution is dipped on the silicon-aluminum composite carrier in an equal volume. After dipping, aging for 1 hour, then placing the product in a baking oven at 100 ℃ overnight for drying, and roasting the obtained catalyst at high temperature of 750 ℃ for 2 hours to obtain the catalyst cat 3.

The mass fraction of zirconium and the mass fraction of gallium in the catalyst obtained in this example were 1.89% and 2.23%, respectively. The specific surface area, pore volume and pore diameter of the catalyst are shown in Table 1, and the X-ray diffraction pattern is shown in FIG. 1.

Example 4

According to the mass ratio of metal zirconium to metal gallium of 1:3.5, a certain amount of zirconium and gallium precursor zirconium nitrate and gallium nitrate are weighed and prepared into a mixed solution, and then the mixed solution is dipped on the silicon-aluminum composite carrier in an equal volume. After dipping, aging for 1 hour, then placing the product in an oven at 100 ℃ for overnight drying, and roasting the obtained catalyst for 2 hours at high temperature of 750 ℃ to obtain catalyst cat 4.

The mass fraction of zirconium and the mass fraction of gallium in the catalyst obtained in this example were 0.97% and 3.25%, respectively. The specific surface area, pore volume and pore diameter of the catalyst are shown in Table 1, and the X-ray diffraction pattern is shown in FIG. 1.

Example 5

According to the mass ratio of metal zirconium to metal gallium of 0.5:4, a certain amount of zirconium and gallium precursor zirconium nitrate and gallium nitrate are weighed and prepared into a mixed solution, and then the mixed solution is dipped on the silicon-aluminum composite carrier in an equal volume. After dipping, aging for 1 hour, then placing the product in an oven at 100 ℃ for overnight drying, and roasting the obtained catalyst for 2 hours at high temperature of 750 ℃ to obtain the catalyst cat 5.

The mass fraction of zirconium and the mass fraction of gallium in the catalyst obtained in this example were 0.51% and 3.34%, respectively. The specific surface area, pore volume and pore diameter of the catalyst are shown in Table 1, and the X-ray diffraction pattern is shown in FIG. 1.

Example 6

Weighing a certain amount of gallium nitrate, preparing a solution, and soaking the solution on the silicon-aluminum composite carrier in an equal volume. After dipping, aging for 1 hour, then placing the product in an oven at 100 ℃ for overnight drying, and roasting the obtained catalyst for 2 hours at high temperature of 750 ℃ to obtain the catalyst cat 6.

The mass fraction of gallium in the catalyst obtained in this example was 4.34%. The specific surface area, pore volume and pore diameter of the catalyst are shown in Table 1, and the X-ray diffraction pattern is shown in FIG. 1.

TABLE 1 chemical and physical Properties of the different catalysts

Example 7

After the catalysts cat 1 to cat 6 prepared in the above examples 1 to 6 are prepared, the catalyst cat 1 to cat 6 are tableted and sieved, and 0.4g of 60 to 80 mesh catalyst and quartz sand are selected according to the weight ratio of 1:3, mixing uniformly and putting into a quartz reactor.

The catalyst needs to pass through H before reaction₂/N₂(10%) for 30 minutes to 600 degrees celsius. Butane, hydrogen and nitrogen were then mixed in a ratio of 1: 1: a volume ratio of 8 was introduced into the reaction tube, and the total flow rate was 100 ml/min. The reaction is carried out under normal pressure, the temperature is 600 ℃, and the hourly space velocity of gas is 20-300h^-1。

The gas phase analysis of the product gave the results shown in FIGS. 2 and 3. As shown in fig. 2, the conversion rate of butane can reach more than 90%, and the selectivity can reach 60% at most; as shown in FIG. 3, the selectivity of butadiene in the product reaches about 17% at most, and the selectivity of total butylene reaches 81.5% at most.

The foregoing description has disclosed fully preferred embodiments of the present invention. It should be noted that those skilled in the art can make modifications to the embodiments of the present invention without departing from the scope of the appended claims. Accordingly, the scope of the appended claims is not to be limited to the specific embodiments described above.

Claims

1. A method for preparing butylene and butadiene by butane catalytic dehydrogenation is characterized in that: carrying out dehydrogenation reaction on butane in the presence of a dehydrogenation catalyst, and separating butene and butadiene from the obtained dehydrogenation product; the dehydrogenation catalyst comprises zirconium and gallium as active components; the butane is co-fed with hydrogen, wherein the molar ratio of hydrogen to butane is from 0.1 to 10; the reaction temperature is 500-750 ℃, the reaction pressure is 0-0.3Mpa, and the gas hourly volume space velocity is 20-300h^-1(ii) a The active component in the dehydrogenation catalyst accounts for 3-5% of the total mass of the catalyst; the mass ratio of zirconium to gallium in the active component in the dehydrogenation catalyst is 0.15-0.81.

2. The process for the catalytic dehydrogenation of butane to produce butene and butadiene according to claim 1, wherein the dehydrogenation catalyst is prepared by: