CN114618470B - Composite catalyst and preparation method and application thereof - Google Patents

Abstract

The application discloses a composite catalyst and a preparation method and application thereof. The application provides a low-cost and environment-friendly catalyst for preparing propylene by dehydrogenating propane; the catalyst can be applied to the development of a circulating fluidized bed process, and the development of a new propane dehydrogenation technology is promoted.

Description

Composite catalyst and preparation method and application thereof

Technical Field

The application relates to a composite catalyst, a preparation method and application thereof, and belongs to the technical field of catalysts.

Background

Propylene is a basic chemical raw material and mainly comes from naphtha catalytic cracking, methanol-to-olefin, propane dehydrogenation and the like. Wherein the dehydrogenation of propane has been developed more rapidly due to the increase in the yield of propane and the reduction in cost.

At present, the propane dehydrogenation catalyst is mainly a Pt-based catalyst and a Cr-based catalyst. The propane dehydrogenation process is limited by thermomechanics, and the reaction temperature has serious influence on the conversion rate. To ensure the conversion of propane, the dehydrogenation reaction temperature of propane is between 580 and 630 ℃. At this temperature, deactivation of the catalyst by coking is difficult to avoid, and coking regeneration of the catalyst is a major means of restoring activity. The noble metal Pt is high in price, so that chromium oxide has great toxicity to the environment, and the problems of catalyst breakage and running loss are difficult to bear, so that a circulating fluidized bed process cannot be adopted. The Pt catalyst mainly adopts a moving bed process, while the chromium oxide catalyst adopts a multi-reactor fixed bed reactor which is connected in parallel, and the operation process is complex and tedious. Therefore, the development of a novel catalyst which is low in price and environment-friendly is a main development direction of a propane dehydrogenation catalyst.

Disclosure of Invention

Aiming at the problems, the application provides a low-cost and environment-friendly composite catalyst for preparing propylene by dehydrogenating propane, and a preparation method and application thereof.

According to a first aspect of the present application, there is provided a composite catalyst prepared by sequentially subjecting a mixture of a zinc source, a gallium source, an aluminum source and a hydroxy acid to reaction I, drying, and calcining.

Optionally, the composite catalyst is composed of four elements of zinc, gallium, aluminum and oxygen; the mass ratio of the zinc element to the gallium element to the aluminum element is 13.6-62.0: 0.6 to 7.8:30.2 to 85.8.

Optionally, the hydroxy acid is at least one of citric acid, tartaric acid, lactic acid and malic acid;

the zinc source is at least one selected from zinc nitrate, zinc chloride and zinc sulfate;

the gallium source is selected from at least one of gallium nitrate, gallium chloride and gallium sulfate;

the aluminum source is at least one selected from aluminum nitrate, aluminum chloride and aluminum sulfate.

According to a second aspect of the present application, there is provided a method for preparing the above composite catalyst, the method comprising:

(1) Reacting a mixture consisting of a zinc source, a gallium source, an aluminum source and hydroxy acid to obtain sol;

(2) And drying and roasting the material containing the sol to obtain the composite catalyst.

Optionally, in the step (1), the molar ratio of the zinc source, the gallium source and the aluminum source is 13.6-62.0: 0.6 to 7.8:30.2 to 85.8;

the mole number of the gallium source is calculated by the mole number of the metal gallium; the number of moles of the aluminum source is calculated by the number of moles of metallic aluminum; the mole number of the zinc source is calculated by the mole number of the metallic zinc;

the molar ratio of the metal source to the hydroxy acid is 100:10 to 100;

the mole number of the metal source is the sum of the mole numbers of the zinc source, the gallium source and the aluminum source; the number of moles of the hydroxy acid is calculated as the number of moles of the hydroxy acid itself.

Alternatively, the composite catalyst of the present application is prepared by a sol-gel method.

Optionally, in the step (1), the conditions of the reaction I are: the temperature is 20-80 ℃; the time is 0.5-5h;

in the step (2), the drying conditions are as follows: the temperature is 50-200 ℃; the time is 4-20 h;

the roasting conditions are as follows: the temperature is 300-700 ℃; the time is 4-20 h.

Specifically, the composite catalyst is not obtained by simply and physically mixing zinc oxide, aluminum oxide and gallium oxide, but has a specific morphology and structure.

According to a final aspect of the present application, there is provided a process for the preparation of propylene, the process comprising: the raw material gas containing propane is reacted with II in the presence of a catalyst to obtain the propylene;

the catalyst is at least one selected from the composite catalyst and the composite catalyst prepared by the method;

alternatively, the conditions of reaction II are: the reaction temperature is 530-630 ℃; the reaction space velocity is 200-600L Kg ^{- 1} h ^-1 。

Alternatively, the pressure of reaction II is atmospheric.

Alternatively, the upper limit of the reaction temperature is independently selected from 540 ℃,550 ℃, 560 ℃, 570 ℃, 580 ℃, 590 ℃,600 ℃, 610 ℃, 620 ℃ or 630 ℃; the lower limit is selected from 530 ℃, 540 ℃,550 ℃, 560 ℃, 570 ℃, 580 ℃, 590 ℃,600 ℃, 610 ℃, 620 ℃ or 625 ℃.

Alternatively, the upper limit of the propane mass space velocity is selected from 220 Kg ^-1 h ^-1 、240L Kg ^-1 h ^-1 、260L Kg ^-1 h ^-1 、280L Kg ^-1 h ^-1 、300L Kg ^-1 h ^-1 、350L Kg ^-1 h ^-1 、400L Kg ^-1 h ^-1 、450L Kg ^-1 h ^-1 、500L Kg ^-1 h ^-1 、550L Kg ^-1 h ^-1 Or 600L Kg ^-1 h ^-1 The method comprises the steps of carrying out a first treatment on the surface of the The lower limit is selected from 200L Kg ^-1 h ^-1 、220L Kg ^-1 h ^-1 、240L Kg ^-1 h ^-1 、260L Kg ^-1 h ^-1 、280L Kg ^{- 1} h ^-1 、300L Kg ^-1 h ^-1 、350L Kg ^-1 h ^-1 、400L Kg ^-1 h ^-1 、450L Kg ^-1 h ^-1 、500L Kg ^-1 h ^-1 、550L Kg ^-1 h ^-1 Or 580L Kg ^-1 h ^-1 。

The application has the beneficial effects that:

(1) Provides a low-cost and environment-friendly catalyst for preparing propylene by dehydrogenating propane;

(2) The catalyst can be applied to the development of a circulating fluidized bed process, and the development of a new propane dehydrogenation technology is promoted.

Drawings

FIG. 1 is an XRD pattern for catalyst 1;

fig. 2 is an XRD pattern of the mixed catalyst 1.

Detailed Description

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

Unless otherwise indicated, all starting materials in the examples of the present application were purchased commercially.

The analysis method in the embodiment of the application is as follows:

the raw materials and the products were detected by Agilent 7890B gas chromatography from Agilent corporation using PLOT-Q capillary column from Agilent corporation.

In the examples of the present application, the propane conversion and propylene selectivity were calculated based on the number of moles of carbon.

In the embodiment of the application, the conversion rate and selectivity are calculated as follows:

propane conversion = [ (moles of propane in feed) - (moles of propane in discharge) ] +.f. (moles of propane in feed) × (100%)

Propylene selectivity = [ moles of propylene carbon in the effluent ]/[ (moles of propane carbon in the feed) - (moles of propane carbon in the effluent) ]× (100%).

Example 1

2.01g of zinc nitrate, 0.191g of gallium nitrate, 1.5876g of aluminum nitrate and 0.5389g of lactic acid are weighed into 10ml of water, stirred at 20 ℃ until the solution is completely dissolved, and stirred for 300 minutes to obtain a sol. Drying the sol at 80 ℃ for 18 hours, and roasting at 500 ℃ for 12 hours to obtain the catalyst 1. The XRD pattern of catalyst 1 is shown in FIG. 1.

Example 2

1.1152g of zinc chloride, 0.1879g of gallium chloride, 0.9945g of aluminum chloride and 0.1832g of malic acid are weighed into 10ml of water, stirred at 50 ℃ until the mixture is completely dissolved, and stirred for 60 minutes to obtain sol. Drying the sol at 50 ℃ for 20 hours, and roasting at 300 ℃ for 20 hours to obtain the catalyst 2.

Example 3

1.6445g of zinc nitrate, 0.2729g of gallium nitrate, 2.0889g of aluminum nitrate and 1.6673g of citric acid are weighed into 10ml of water, stirred at 30 ℃ until the solution is completely dissolved, and stirred for 240 minutes to obtain a sol. Drying the sol at 150 ℃ for 10 hours, and roasting at 650 ℃ for 5 hours to obtain the catalyst 3.

Example 4

0.7064g of zinc sulfate, 0.0238g of gallium sulfate, 5.1635g of aluminum sulfate and 2.7106g of tartaric acid are weighed into 10ml of water, stirred at 80 ℃ until the solution is completely dissolved, and stirred for 30 minutes to obtain sol. Drying the sol at 200 ℃ for 4 hours, and roasting at 700 ℃ for 4 hours to obtain the catalyst 4.

Example 5

1.2791g of zinc nitrate, 0.0819g of gallium nitrate, 2.5067g of aluminum nitrate and 1.4759g of tartaric acid are weighed into 10ml of water, stirred at 50 ℃ until the solution is completely dissolved, and stirred for 60 minutes to obtain a sol. Drying the sol at 110 ℃ for 12 hours, and roasting at 600 ℃ for 6 hours to obtain the catalyst 5.

Example 6

0.9136g of zinc nitrate, 0.0546g of gallium nitrate, 3.0498g of aluminum nitrate and 1.6523g of malic acid are weighed into 10ml of water, stirred at 60 ℃ until the mixture is completely dissolved, and stirred for 40 minutes to obtain a sol. Drying the sol at 100 ℃ for 12 hours, and roasting at 550 ℃ for 12 hours to obtain the catalyst 6.

Example 7

0.7309g of zinc nitrate, 0.0273g of gallium nitrate, 3.3005g of aluminum nitrate and 3.036g of citric acid are weighed into 10ml of water, stirred at 70 ℃ until the solution is completely dissolved, and stirred for 30 minutes to obtain sol. Drying the sol at 200 ℃ for 4 hours, and roasting at 700 ℃ for 4 hours to obtain the catalyst 7.

Example 8

2.5216g of zinc nitrate, 0.2729g of gallium nitrate, 0.8774g of aluminum nitrate and 0.2461g of lactic acid were weighed into 10ml of water, stirred at 50 ℃ until completely dissolved, and stirred for 60 minutes to obtain a sol. Drying the sol at 150 ℃ for 10 hours, and roasting at 600 ℃ for 6 hours to obtain the catalyst 8.

Comparative example 1

2.01g of zinc nitrate, 0.1804g of copper nitrate, 1.5876g of aluminum nitrate and 0.5389g of lactic acid were weighed into 10ml of water, stirred at 20 ℃ until completely dissolved, and stirred for 300 minutes to obtain a sol. Drying the sol at 80 ℃ for 18 hours, and roasting at 500 ℃ for 12 hours to obtain the comparative catalyst 1.

Comparative example 2

0.55g of zinc oxide powder, 0.07g of gallium oxide powder and 0.38g of aluminum oxide powder are weighed and physically mixed to obtain the mixed catalyst 1. Fig. 2 is an XRD pattern of the mixed catalyst 1. From the XRD results, it can be seen that the catalyst 1 of example 1 and the mixed catalyst 1 are completely different substances, i.e., the catalyst 1 obtained in example 1 is not obtained by physical mixing of oxides.

Example 9

The reaction evaluation was performed on the foregoing example catalyst and comparative example catalyst: the catalyst is filled into a fixed bed reactor, the reaction temperature is 530-630 ℃, the reaction pressure is normal pressure, and the reaction space velocity is 200-600L Kg ^-1 h ^-1 . Sampling after 6min of reaction, and the reaction results are shown in Table 1.

TABLE 1 catalyst reaction results

While the application has been described in terms of preferred embodiments, it will be understood by those skilled in the art that various changes and modifications can be made without departing from the scope of the application, and it is intended that the application is not limited to the specific embodiments disclosed.

Claims (6)

1. A process for the preparation of propylene, said process comprising: the raw material gas containing propane is reacted with II in the presence of a catalyst to obtain the propylene;

the catalyst is a composite catalyst prepared by sequentially carrying out reaction I on a mixture consisting of a zinc source, a gallium source, an aluminum source and hydroxy acid, drying and roasting;

the composite catalyst consists of four elements of zinc, gallium, aluminum and oxygen; the mol ratio of the zinc element, the gallium element and the aluminum element is 13.6-62.0: 0.6 to 7.8:30.2 to 85.8.

2. The method for producing propylene according to claim 1, wherein the hydroxy acid is at least one selected from the group consisting of citric acid, tartaric acid, lactic acid and malic acid;

the zinc source is at least one selected from zinc nitrate, zinc chloride and zinc sulfate;

the gallium source is selected from at least one of gallium nitrate, gallium chloride and gallium sulfate;

the aluminum source is at least one selected from aluminum nitrate, aluminum chloride and aluminum sulfate.

3. The method for producing propylene according to claim 1, wherein the method for producing the composite catalyst comprises:

(1) Reacting a mixture consisting of a zinc source, a gallium source, an aluminum source and hydroxy acid to obtain sol;

(2) And drying and roasting the material containing the sol to obtain the composite catalyst.

4. A method for producing propylene according to claim 3, wherein in the step (1), the molar ratio of the zinc source, the gallium source and the aluminum source is 13.6 to 62.0:0.6 to 7.8:30.2 to 85.8;

the mole number of the gallium source is calculated by the mole number of the metal gallium; the number of moles of the aluminum source is calculated by the number of moles of metallic aluminum; the mole number of the zinc source is calculated by the mole number of the metallic zinc;

the molar ratio of the metal source to the hydroxy acid is 100:10 to 100;

the mole number of the metal source is the sum of the mole numbers of the zinc source, the gallium source and the aluminum source; the number of moles of the hydroxy acid is calculated as the number of moles of the hydroxy acid itself.

5. A process for the preparation of propylene according to claim 3, wherein in step (1), the conditions of reaction I are: the temperature is 20-80 ℃; the time is 0.5-5h;

in the step (2), the drying conditions are as follows: the temperature is 50-200 ℃; the time is 4-20 h;

the roasting conditions are as follows: the temperature is 300-700 ℃; the time is 4-20 h.

6. The process for the preparation of propylene according to claim 1, characterized in that the conditions of reaction II are: the reaction temperature is 530-630 ℃; the reaction space velocity is 200-600L Kg ^-1 h ^-1 。