阅读说明：本技术 一种钴铈锆复合氧化物催化剂及制备方法 (Cobalt-cerium-zirconium composite oxide catalyst and preparation method thereof ) 是由 郭明星 黄均妍 尹淑慧 于 2021-08-05 设计创作，主要内容包括：本发明公开了一种钴铈锆复合氧化物催化剂及制备方法,通过将钴盐、铈盐和锆盐按照一定比例加入无水乙醇溶液中,然后在20～25℃下,搅拌0.5～6h,得到前驱液；向前驱液中加入配制的草酸乙醇溶液,搅拌0.5～3h后干燥,得到草酸盐前驱体,焙烧,压片,得到钴铈锆复合氧化物催化剂。本发明的一种钴铈锆复合氧化物催化剂及制备方法,该催化剂具有催化活性高,环境污染小、成本低廉、制备工艺简单和可行性高的特点。当温度为400℃时,Zr：Ce与Zr物质的量之比为0.15：1时的乙苯转化率达到最高为73.6％,苯乙烯的选择性可达98.96％,具有良好的催化效果。(The invention discloses a cobalt-cerium-zirconium composite oxide catalyst and a preparation method thereof, wherein a cobalt salt, a cerium salt and a zirconium salt are added into an absolute ethyl alcohol solution according to a certain proportion, and then stirred for 0.5-6 h at the temperature of 20-25 ℃ to obtain a precursor solution; and adding the prepared oxalic acid ethanol solution into the precursor solution, stirring for 0.5-3 h, drying to obtain an oxalate precursor, roasting, and tabletting to obtain the cobalt-cerium-zirconium composite oxide catalyst. The cobalt-cerium-zirconium composite oxide catalyst and the preparation method thereof have the characteristics of high catalytic activity, small environmental pollution, low cost, simple preparation process and high feasibility. When the temperature is 400 ℃, Zr: the ratio of the amount of Ce to the amount of Zr species was 0.15: the conversion rate of ethylbenzene in the time 1 reaches 73.6 percent at most, the selectivity of styrene reaches 98.96 percent, and the catalyst has good catalytic effect.)

1. The preparation method of the cobalt-cerium-zirconium composite oxide catalyst is characterized by comprising the following steps of:

s1: adding cobalt salt, cerium salt and zirconium salt into an absolute ethanol solution according to a certain proportion, and then stirring for 0.5-6 h at the temperature of 20-25 ℃ to obtain a precursor solution;

s2: adding the prepared oxalic acid ethanol solution into the precursor solution in the step S1, stirring for 0.5-3 h, and drying to obtain an oxalate precursor;

s3: and (4) roasting the oxalate precursor in the step S2, and tabletting to obtain the cobalt-cerium-zirconium composite oxide catalyst.

2. The method of claim 1, wherein the molar ratio of the cobalt salt, the cerium salt, and the zirconium salt in step S1 is 1-2: 0.1-1: 0.1 to 1.

3. The method of claim 2, wherein the cobalt salt, cerium salt and zirconium salt are one of hydrochloride, sulfate or nitrate.

4. The method of claim 3, wherein the cobalt salt, cerium salt and zirconium salt are nitrates.

5. The method of claim 1, wherein in step S2, the prepared oxalic acid ethanol solution has a concentration of 1-3 mol/L, the drying temperature is 70-120 ℃, and the drying time is 8-16 h.

6. The method of claim 1, wherein in step S3, the calcination temperature is 300-500 ℃ and the calcination time is 3-7 hours.

7. A cobalt cerium zirconium composite oxide catalyst, characterized in that the catalyst is prepared according to the preparation method of the cobalt cerium zirconium composite oxide catalyst of any one of claims 1 to 6.

Technical Field

The invention relates to the technical field of catalysis, in particular to a cobalt-cerium-zirconium composite oxide catalyst and a preparation method thereof.

Background

Styrene is an important basic organic chemical raw material, is widely used for synthesizing plastics and rubber, has annual output of ten thousand tons all over the world, mainly comprises resins such as polystyrene, acrylonitrile-butadiene-styrene copolymer, styrene-acrylonitrile and the like, and is the fourth major ethylene derivative product which is second only to polyethylene, polyvinyl chloride and ethylene oxide. There are three main industrial processes for the production of styrene: the method comprises an ethylbenzene direct dehydrogenation process, a propylene oxide/styrene co-production process and an ethylbenzene dehydrogenation-hydrogen selective oxidation process, wherein more than 87% of styrene production devices in the world adopt the ethylbenzene direct dehydrogenation process.

The catalysts used in the prior ethylbenzene direct dehydrogenation process are divided into two types: one is Fe-K-Cr series catalyst containing Cr, which has high activity and stability, but Cr is extremely toxic and has serious environmental pollution and is eliminated. The other is Fe-K-Ce-Mo series, the activity and selectivity of the catalyst are higher, but K is used as a cocatalyst in the component₂The content of O is high, and because of the strong water absorption of potassium, when the catalyst is placed in the air, the catalyst with high potassium content is easy to absorb water, so that the crushing resistance of catalyst particles is reduced, and the catalyst particles are easy to pulverize; in addition, during the dehydrogenation reaction, potassium gradually migrates to the interior of the particles or is easily washed away, so that potassium is lost, the stability of the catalyst is reduced, and the service life of the catalyst is shortened. Therefore, it is a subject of interest for researchers to find a catalyst for ethylbenzene dehydrogenation with high catalytic activity and stability and low cost.

Disclosure of Invention

The invention provides a cobalt-cerium-zirconium composite oxide catalyst and a preparation method thereof, which aim to solve the problems of low activity and complex preparation process of the conventional ethylbenzene dehydrogenation catalyst.

In order to achieve the purpose, the technical scheme of the invention is as follows:

a preparation method of a cobalt-cerium-zirconium composite oxide catalyst comprises the following steps:

s1: adding cobalt salt, cerium salt and zirconium salt into an absolute ethanol solution according to a certain proportion, and then stirring for 0.5-6 h at the temperature of 20-25 ℃ to obtain a precursor solution;

s2: adding the prepared oxalic acid ethanol solution into the precursor solution in the step S1, stirring for 0.5-3 h, and drying to obtain an oxalate precursor;

s3: and (4) roasting the oxalate precursor in the step S2, and tabletting to obtain the cobalt-cerium-zirconium composite oxide catalyst.

Further, the molar ratio of the cobalt salt, the cerium salt and the zirconium salt in the step S1 is 1-2: 0.1-1: 0.1 to 1.

Further, the cobalt salt, the cerium salt and the zirconium salt are one of hydrochloride, sulfate or nitrate.

Further, the cobalt salt, the cerium salt and the zirconium salt are nitrates.

Further, in the step S2, the concentration of the prepared oxalic acid ethanol solution is 1-3 mol/L, the drying temperature is 70-120 ℃, and the time is 8-16 h.

Further, in the step S3, the roasting temperature is 300-500 ℃ and the time is 3-7 hours.

A cobalt cerium zirconium composite oxide catalyst is prepared according to a preparation method of the cobalt cerium zirconium composite oxide catalyst.

The cobalt-cerium-zirconium composite oxide catalyst and the preparation method thereof have the characteristics of high catalytic activity, small environmental pollution, low cost, simple preparation process and high feasibility. When the temperature is 400 ℃, Zr: the ratio of the amount of Ce to the amount of Zr species was 0.15: the conversion rate of ethylbenzene in the time 1 reaches 73.6 percent at most, the selectivity of styrene reaches 98.96 percent, and the catalyst has good catalytic effect.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are some embodiments of the present invention, but not all embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1:

as cobalt (Co): the ratio of the amount of cerium (Ce) species is 9: 1 weighing a certain amount of cobalt nitrate hexahydrate and cerium nitrate hexahydrate, respectively dissolving in absolute ethyl alcohol to prepare a 1mol/L ethanol solution, then mixing the solution under a mechanical stirring state, and continuously stirring for 30 min. And dropwise adding an oxalic acid ethanol solution with the concentration of 1mol/L into the mixed solution, continuously stirring at room temperature for 1h to obtain an oxalate precursor, quickly transferring the oxalate precursor into a drying oven with the temperature of 80 ℃ for drying for 12h, roasting in a muffle furnace at the temperature of 400 ℃ for 4h, and tabletting under the pressure of 18Mpa to obtain the 20-40-mesh composite oxide catalyst, wherein the label is Cat.1. The preparation method comprises the following steps of preparing an oxalic acid ethanol solution, namely quantifying by adopting a volumetric flask, accurately weighing oxalic acid according to the concentration of the required oxalic acid ethanol solution, dissolving the oxalic acid in absolute ethyl alcohol, transferring the oxalic acid ethanol solution to a volumetric flask of 100ml, shaking up and fixing the volume; the tabletting is to pursue a large specific surface area and a fine catalyst carrier particle size in the process of preparing the catalyst, prevent air flow blockage and enable the catalyst to participate in the reaction more fully in the fixed bed reaction.

0.5g of the prepared Cat.1 catalyst was loaded in a fixed bed stainless steel reaction tube, the upper and lower parts of which were loaded with quartz wool, and then carrier gas N was introduced₂Ethylbenzene is brought into a reactor to perform catalytic reaction for 1 hour, the composition of a product after the reaction is detected by using a gas chromatograph GC-7900, the ethylbenzene conversion rate and the styrene selectivity are calculated by correcting an area normalization method, and specific catalyst activity evaluation results are shown in Table 1.

Example 2:

as cobalt (Co): the ratio of the amounts of cerium (Ce) and zirconium (Zr) species was 9: 1, Zr: the ratio of the amount of Ce to the amount of Zr species was 0.05: 1 weighing a certain amount of cobalt nitrate hexahydrate, cerium nitrate hexahydrate and zirconyl nitrate, respectively dissolving in absolute ethyl alcohol to prepare 1mol/L ethanol solution, then mixing the ethanol solution in a mechanical stirring state, and continuously stirring for 30 min. And dropwise adding an oxalic acid ethanol solution with the concentration of 1mol/L into the mixed solution, continuously stirring at room temperature for 1h to obtain an oxalate precursor, quickly transferring the oxalate precursor into a drying oven with the temperature of 80 ℃ for drying for 12h, roasting in a muffle furnace at the temperature of 400 ℃ for 4h, and tabletting under the pressure of 18Mpa to obtain the 20-40-mesh composite oxide catalyst, wherein the label is Cat.2. The preparation method comprises the following steps of preparing an oxalic acid ethanol solution, namely quantifying by adopting a volumetric flask, accurately weighing oxalic acid according to the concentration of the required oxalic acid ethanol solution, dissolving the oxalic acid in absolute ethyl alcohol, transferring the oxalic acid ethanol solution to a volumetric flask of 100ml, shaking up and fixing the volume; the tabletting is to pursue a large specific surface area and a fine catalyst carrier particle size in the process of preparing the catalyst, prevent air flow blockage and enable the catalyst to participate in the reaction more fully in the fixed bed reaction.

0.5g of the prepared Cat.2 catalyst was loaded in a fixed bed stainless steel reaction tube, the upper and lower parts of which were loaded with quartz wool, and then carrier gas N was introduced₂Ethylbenzene is brought into a reactor to perform catalytic reaction for 1 hour, the composition of a product after the reaction is detected by using a gas chromatograph GC-7900, the ethylbenzene conversion rate and the styrene selectivity are calculated by correcting an area normalization method, and specific catalyst activity evaluation results are shown in Table 1.

Example 3:

according to the weight ratio of Co: the ratio of the amount of Ce to the amount of Zr species is 9: 1, Zr: the ratio of the amount of Ce to the amount of Zr species is 0.1: 1 weighing a certain amount of cobalt nitrate hexahydrate, cerium nitrate hexahydrate and zirconyl nitrate, respectively dissolving in absolute ethyl alcohol to prepare 1mol/L ethanol solution, then mixing the ethanol solution in a mechanical stirring state, and continuously stirring for 30 min. And dropwise adding an oxalic acid ethanol solution with the concentration of 1mol/L into the mixed solution, continuously stirring at room temperature for 1h to obtain an oxalate precursor, quickly transferring the oxalate precursor into a drying oven at 80 ℃ for drying for 12h, roasting in a muffle furnace at 400 ℃ for 4h, and tabletting under the pressure of 18Mpa to obtain the 20-40-mesh composite oxide catalyst, wherein the label is Cat.3. The preparation method comprises the following steps of preparing an oxalic acid ethanol solution, namely quantifying by adopting a volumetric flask, accurately weighing oxalic acid according to the concentration of the required oxalic acid ethanol solution, dissolving the oxalic acid in absolute ethyl alcohol, transferring the oxalic acid ethanol solution to a volumetric flask of 100ml, shaking up and fixing the volume; the tabletting is to pursue a large specific surface area and a fine catalyst carrier particle size in the process of preparing the catalyst, prevent air flow blockage and enable the catalyst to participate in the reaction more fully in the fixed bed reaction.

0.5g of the prepared Cat.3 catalyst was loaded in a fixed bed stainless steel reaction tube, the upper and lower parts of which were loaded with quartz wool, and then carrier gas N was introduced₂Ethylbenzene is brought into a reactor to perform catalytic reaction for 1 hour, the composition of a product after the reaction is detected by using a gas chromatograph GC-7900, the ethylbenzene conversion rate and the styrene selectivity are calculated by correcting an area normalization method, and specific catalyst activity evaluation results are shown in Table 1.

Example 4:

according to the weight ratio of Co: the ratio of the amount of Ce to the amount of Zr species is 9: 1, Zr: the ratio of the amount of Ce to the amount of Zr species was 0.15: 1 weighing a certain amount of cobalt nitrate hexahydrate, cerium nitrate hexahydrate and zirconyl nitrate, respectively dissolving in absolute ethyl alcohol to prepare 1mol/L ethanol solution, then mixing the ethanol solution in a mechanical stirring state, and continuously stirring for 30 min. And dropwise adding an oxalic acid ethanol solution with the concentration of 1mol/L into the mixed solution, continuously stirring at room temperature for 1h to obtain an oxalate precursor, quickly transferring the oxalate precursor into a drying oven at 80 ℃ for drying for 12h, roasting in a muffle furnace at 400 ℃ for 4h, and tabletting under the pressure of 18Mpa to obtain the 20-40-mesh composite oxide catalyst, wherein the label is Cat.4. The preparation method comprises the following steps of preparing an oxalic acid ethanol solution, namely quantifying by adopting a volumetric flask, accurately weighing oxalic acid according to the concentration of the required oxalic acid ethanol solution, dissolving the oxalic acid in absolute ethyl alcohol, transferring the oxalic acid ethanol solution to a volumetric flask of 100ml, shaking up and fixing the volume; the tabletting is to pursue a large specific surface area and a fine catalyst carrier particle size in the process of preparing the catalyst, prevent air flow blockage and enable the catalyst to participate in the reaction more fully in the fixed bed reaction.

0.5g of the prepared Cat.4 catalyst was loaded in a fixed bed stainless steel reaction tube, the upper and lower parts of which were loaded with quartz wool, and then carrier gas N was introduced₂Ethylbenzene is brought into a reactor to perform catalytic reaction for 1 hour, the composition of a product after the reaction is detected by using a gas chromatograph GC-7900, the ethylbenzene conversion rate and the styrene selectivity are calculated by correcting an area normalization method, and specific catalyst activity evaluation results are shown in Table 1.

Example 5:

according to the weight ratio of Co: the ratio of the amount of Ce to the amount of Zr species is 9: 1, Zr: the ratio of the amount of Ce to the amount of Zr species was 0.2: 1 weighing a certain amount of cobalt nitrate hexahydrate, cerium nitrate hexahydrate and zirconyl nitrate, respectively dissolving in absolute ethyl alcohol to prepare 1mol/L ethanol solution, then mixing the ethanol solution in a mechanical stirring state, and continuously stirring for 30 min. And dropwise adding an oxalic acid ethanol solution with the concentration of 1mol/L into the mixed solution, continuously stirring at room temperature for 1h to obtain an oxalate precursor, quickly transferring the oxalate precursor into a drying oven at 80 ℃ for drying for 12h, roasting in a muffle furnace at 400 ℃ for 4h, and tabletting under the pressure of 18Mpa to obtain the 20-40-mesh composite oxide catalyst, wherein the label is Cat.5. The preparation method comprises the following steps of preparing an oxalic acid ethanol solution, namely quantifying by adopting a volumetric flask, accurately weighing oxalic acid according to the concentration of the required oxalic acid ethanol solution, dissolving the oxalic acid in absolute ethyl alcohol, transferring the oxalic acid ethanol solution to a volumetric flask of 100ml, shaking up and fixing the volume; the tabletting is to pursue a large specific surface area and a fine catalyst carrier particle size in the process of preparing the catalyst, prevent air flow blockage and enable the catalyst to participate in the reaction more fully in the fixed bed reaction.

0.5g of the prepared Cat.5 catalyst was loaded in a fixed bed stainless steel reaction tube, the upper and lower parts of which were loaded with quartz wool, and then carrier gas N was introduced₂Ethylbenzene is brought into a reactor to perform catalytic reaction for 1 hour, the composition of a product after the reaction is detected by using a gas chromatograph GC-7900, the ethylbenzene conversion rate and the styrene selectivity are calculated by correcting an area normalization method, and specific catalyst activity evaluation results are shown in Table 1.

Example 6.

According to the weight ratio of Co: the ratio of the amount of Ce to the amount of Zr species is 9: 1, Zr: the ratio of the amount of Ce to the amount of Zr species was 0.15: 1 weighing a certain amount of cobalt nitrate hexahydrate, cerium nitrate hexahydrate and zirconyl nitrate, respectively dissolving in absolute ethyl alcohol to prepare 1mol/L ethanol solution, then mixing the ethanol solution in a mechanical stirring state, and continuously stirring for 30 min. And dropwise adding an oxalic acid ethanol solution with the concentration of 1mol/L into the mixed solution, continuously stirring at room temperature for 1h to obtain an oxalate precursor, quickly transferring the oxalate precursor into a drying oven at 80 ℃ for drying for 12h, roasting in a muffle furnace at 300 ℃ for 4h, and tabletting under the pressure of 18Mpa to obtain the 20-40-mesh composite oxide catalyst, wherein the label is Cat.6. The preparation method comprises the following steps of preparing an oxalic acid ethanol solution, namely quantifying by adopting a volumetric flask, accurately weighing oxalic acid according to the concentration of the required oxalic acid ethanol solution, dissolving the oxalic acid in absolute ethyl alcohol, transferring the oxalic acid ethanol solution to a volumetric flask of 100ml, shaking up and fixing the volume; the tabletting is to pursue a large specific surface area and a fine catalyst carrier particle size in the process of preparing the catalyst, prevent air flow blockage and enable the catalyst to participate in the reaction more fully in the fixed bed reaction.

0.5g of the prepared Cat.6 catalyst was loaded in a fixed bed stainless steel reaction tube, the upper and lower parts of which were loaded with quartz wool, and then carrier gas N was introduced₂Ethylbenzene is brought into a reactor to perform catalytic reaction for 1 hour, the composition of a product after the reaction is detected by using a gas chromatograph GC-7900, the ethylbenzene conversion rate and the styrene selectivity are calculated by correcting an area normalization method, and specific catalyst activity evaluation results are shown in Table 1. The preparation method comprises the following steps of preparing an oxalic acid ethanol solution, namely quantifying by adopting a volumetric flask, accurately weighing oxalic acid according to the concentration of the required oxalic acid ethanol solution, dissolving the oxalic acid in absolute ethyl alcohol, transferring the oxalic acid ethanol solution to a volumetric flask of 100ml, shaking up and fixing the volume; the tabletting is to pursue a large specific surface area and a fine catalyst carrier particle size in the process of preparing the catalyst, prevent air flow blockage and enable the catalyst to participate in the reaction more fully in the fixed bed reaction.

Example 7

According to the weight ratio of Co: the ratio of the amount of Ce to the amount of Zr species is 9: 1, Zr: the ratio of the amount of Ce to the amount of Zr species was 0.15: 1 weighing a certain amount of cobalt nitrate hexahydrate, cerium nitrate hexahydrate and zirconyl nitrate, respectively dissolving in absolute ethyl alcohol to prepare 1mol/L ethanol solution, then mixing the ethanol solution in a mechanical stirring state, and continuously stirring for 30 min. And dropwise adding an oxalic acid ethanol solution with the concentration of 1mol/L into the mixed solution, continuously stirring at room temperature for 1h to obtain an oxalate precursor, quickly transferring the oxalate precursor into a drying oven with the temperature of 80 ℃ for drying for 12h, roasting in a muffle furnace at the temperature of 500 ℃ for 4h, and tabletting under the pressure of 18Mpa to obtain the 20-40-mesh composite oxide catalyst, wherein the label is Cat.7. The preparation method comprises the following steps of preparing an oxalic acid ethanol solution, namely quantifying by adopting a volumetric flask, accurately weighing oxalic acid according to the concentration of the required oxalic acid ethanol solution, dissolving the oxalic acid in absolute ethyl alcohol, transferring the oxalic acid ethanol solution to a volumetric flask of 100ml, shaking up and fixing the volume; the tabletting is to pursue a large specific surface area and a fine catalyst carrier particle size in the process of preparing the catalyst, prevent air flow blockage and enable the catalyst to participate in the reaction more fully in the fixed bed reaction.

0.5g of the prepared Cat.7 catalyst was loaded in a fixed bed stainless steel reaction tube, the upper and lower parts of which were loaded with quartz wool, and then carrier gas N was introduced₂Ethylbenzene is brought into a reactor to perform catalytic reaction for 1 hour, the composition of a product after the reaction is detected by using a gas chromatograph GC-7900, the ethylbenzene conversion rate and the styrene selectivity are calculated by correcting an area normalization method, and specific catalyst activity evaluation results are shown in Table 1.

Table 1: performance parameters of different complex oxide catalysts

As can be seen from examples 1 to 5 in table 1, the catalytic activities of the cobalt cerium zirconium composite oxide catalysts were all higher than that of the cobalt cerium oxides. With the increase of the Zr doping amount, the conversion rate of the ethylbenzene shows a tendency of increasing and then decreasing. In example 4, when Zr: the ratio of the amount of Ce to the amount of Zr species was 0.15: the ethylbenzene conversion reached the highest at 1, 73.6%, with styrene selectivity at 98.96% being the best. It can be seen that the addition of Zr in a proper amount can improve the catalytic activity of the cobalt cerium oxide catalyst.

It can be seen from examples 4, 6 and 7 in the table that the calcination temperature has some influence on the catalyst activity. The calcination temperature of the catalyst directly affects the dispersion degree of the catalyst, the decomposition products of the precursor and the like, thereby having a great influence on the activity of the catalyst. When the roasting temperature is 400 ℃, the ethylbenzene conversion rate reaches the highest and is 73.6 percent, and the styrene selectivity is the best and is 98.96 percent. Therefore, the optimum calcination temperature of the cobalt-cerium-zirconium composite oxide catalyst is 400 ℃.

At present, the ethylbenzene conversion rate of the vanadium-loaded catalyst prepared by using the disclosed activated carbon or alumina as a carrier reaches 60%, compared with the prior art, the initial ethylbenzene conversion rate of the cobalt-cerium-zirconium composite oxide catalyst can reach 73.60%, the method is remarkably improved, and the catalyst is few in preparation steps, simple and easy to implement and high in feasibility.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solution of the present invention, and not to limit the same; while the invention has been described in detail and with reference to the foregoing embodiments, it will be understood by those skilled in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some or all of the technical features may be equivalently replaced; and the modifications or the substitutions do not make the essence of the corresponding technical solutions depart from the scope of the technical solutions of the embodiments of the present invention.