ETHYLBENZENE DEHYDROGENATION CATALYST, PREPARATION METHOD THEREFOR, AND USE THEREOF

Abstract

An ethylbenzene dehydrogenation catalyst, a preparation method therefor, and the use thereof are provided. The catalyst includes Fe.sub.2O.sub.3, K.sub.2O, CeO.sub.2, MoO.sub.3 and CaO. The exposed crystal face area of CeO.sub.2 (100) accounts for 60% or more of the total exposed crystal face area of CeO.sub.2. The catalyst is used in a reaction for preparing styrene by means of dehydrogenating ethylbenzene at a low water ratio, and has high activity and stability.

Claims

1. A catalyst, characterized in that the composition of the catalyst is calculated as oxide, the catalyst contains Fe.sub.2O.sub.3, K.sub.2O, CeO.sub.2, MoO.sub.3, and CaO; wherein the area of CeO.sub.2 (100) exposed crystal face comprises 43% or higher, for instance 50% or higher, preferably 60% or higher, more preferably 70% or higher of the area of CeO.sub.2 total exposed crystal face.

2. The catalyst according to claim 1, characterized in that the H.sub.2-TPR main reduction peak position of the catalyst is 570-620 C., such as 570 C., 580 C., 585 C., 590 C., 595 C., 600 C., 605 C., 610 C., 615 C., 620 C.

3. The catalyst according to claim 1, characterized in that, the catalyst includes the following components in mass fraction based on the total mass of the catalyst: (a) 60%-85% of Fe.sub.2O.sub.3; (b) 6%-14% of K.sub.2O; (c) 6%-14% of CeO.sub.2; (d) 0.5%-5% of MoO.sub.3; (e) 0.3%-7% of CaO.

4. The catalyst according to claim 3, characterized in that the catalyst, based on the total mass of the catalyst, in mass fraction, contains 0.01%-2.0% Na.sub.2O.

5. The catalyst according to claim 3, characterized in that the catalyst, based on the total mass of the catalyst, in mass fraction, contains 0.01%-2.0% Na.sub.2O, the catalyst further contains 0.01%-2.0% other metal oxide(s), such as TiO.sub.2.

6. The catalyst according to claim 1, characterized in that, the catalyst is used in the ethylbenzene dehydrogenation, preferably the ethylbenzene dehydrogenation in a low steam/ethylbenzene ratio.

7. A method of preparing the catalyst according to claim 1, characterized in that said method comprises the following steps: mixing a Fe source, a Ce source, a Mo source, a Ca source, optionally a first K source, and optionally a pore-forming agent evenly, then adding an alkaline solution, letting stand for reaction, shaping, and calcining to produce the catalyst; wherein, the K.sub.2O in the catalyst derives from the first K source and/or the alkaline solution, for example, at least 50% of the K.sub.2O in the catalyst derives from an alkaline solution containing K, and the remaining part derives from the first K source; or the K.sub.2O in the catalyst can also all derive from an alkaline solution containing K instead of using the first K source.

8. The preparation method according to claim 7, characterized in that the alkaline solution is an aqueous solution of potassium hydroxide and/or sodium hydroxide, preferably an aqueous solution of sodium hydroxide and potassium hydroxide, the mass ratio of sodium hydroxide as Na.sub.2O to potassium hydroxide as K.sub.2O is preferably 1:2-23; the OH group concentration of the alkaline solution is 1 mol/L-8 mol/L; and/or, the alkaline solution is an aqueous solution of sodium hydroxide and potassium hydroxide, the mass ratio of sodium hydroxide as Na.sub.2O to potassium hydroxide as K.sub.2O is preferably 1:2-23.

9. The preparation method according to claim 7, characterized in that, at least a part of the K.sub.2O in the catalyst derives from the alkaline solution; preferably, at least 50% of the K.sub.2O in the catalyst derives from an alkaline solution containing K, and the remaining part derives from the first K source.

10. The preparation method according to claim 7, characterized in that a raw material further contains a Ti source; the Ti source together with the Fe source, the Ce source, the Mo source, the Ca source, optionally the first K source, and optionally the pore-forming agent is mixed evenly and added; the Ti source is added in form of titanium salt or oxide; preferably, the titanium salt is any one or both of titanium tetrachloride or titanium tetrabromide.

11. The preparation method according to claim 7, characterized in that the condition for letting stand for reaction comprises letting stand for reaction at 120-180 C. for 12-48 hours.

12. The preparation method according to claim 7, characterized in that the calcining temperature is 600-1000 C., the calcining time is 2-8 hours; for example a two-step calcining is used, for example but not limited to calcining at 600-800 C. for 2-4 hours, then calcining at 900-1000 C. for 2-4 hours.

13. The preparation method according to claim 7, characterized in that the calcining is carried out in a muffle furnace.

14. The preparation method according to claim 7, characterized in that a shaped material is firstly dried and then calcined, the drying temperature is 50-200 C., the drying time is 1-24 hours.

15. The preparation method according to claim 7, characterized in that the reaction is carried out under an increased pressure, for example 2-20 atm (gauge pressure).

16. The preparation method according to claim 7, characterized in that the Ce source is added in form of cerium salt, for example the Ce source is cerium nitrate; and/or, the Fe source is added in form of oxide Fe.sub.2O.sub.3, for example the Fe source is preferably selected from iron oxide red and/or iron oxide yellow, more preferably a composition of iron oxide red and iron oxide yellow, wherein the mass ratio of iron oxide red to iron oxide yellow as Fe.sub.2O.sub.3 is 1.0-3.5:1; and/or, the first K source is added in form of potassium salt, the first K source is added in form of potassium salt; the potassium salt is any one or more of potassium carbonate, potassium nitrate, and potassium bicarbonate; and/or, the Mo source is added in form of molybdenum salt or oxide; the molybdenum salt is ammonium molybdate; and/or, the calcium source is added in form of oxide or hydroxide; optionally, the pore-forming agent is any one or more of activated carbon, graphite, sodium carboxymethylcellulose and polystyrene microsphere, and the pore-forming agent is added in an amount of 0-5% of the catalyst mass; optionally, in the preparation method of the catalyst, the Fe source, the Ce source, the Mo source, the Ca source, the first K source, and the pore-forming agent are all added in form of solid phase powder.

17. Use of the catalyst according to claim 1 for producing styrene in the ethylbenzene dehydrogenation.

18. Use according to claim 17, characterized in that the catalyst is suitable for the ethylbenzene dehydrogenation in a low steam/ethylbenzene ratio; the low steam/ethylbenzene ratio is 1.3 or less, preferably 0.7-1.3.

19. Use according to claim 17, characterized in that the catalyst is suitable for the production of styrene with a steam/ethylbenzene ratio of 2.0 or less.

20. Use according to claim 17, characterized in that said use comprises: a raw material gas containing ethylbenzene contacts with the catalyst in the presence of water vapor to perform a dehydrogenation reaction to produce a styrene-containing product; water is pre-heated into water vapor before entering the reactor and thoroughly mixed with the raw material gas; the temperature of the dehydrogenation reaction is 570-640 C.; the pressure of the dehydrogenation reaction is an absolute pressure of 20-100 kPa; the weight hourly space velocity of ethylbenzene is 0.2-2.0 h.sup.1.

Description

DESCRIPTION OF THE DRAWINGS

[0097] FIG. 1 is a photo of the main exposed crystal face in the HAADF-STEM test of the catalyst of Example 1;

[0098] FIG. 2 is a photo of the main exposed crystal face in the HAADF-STEM test of the catalyst of Comparative Example 1;

[0099] FIG. 3 is the H.sub.2-TPR diagram of the catalysts of Example 1 and Comparative Example 1.

DETAILED DESCRIPTION

[0100] The present invention will be further described below through examples, but the protection scope of the present invention is not limited by the examples.

[0101] In the present invention, the area of the exposed crystal surface is measured by a characterization means using a high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and the measuring instrument is the Titan Cubed Themis G2 300 transmission electron microscope with double spherical aberration correction of FEI Company. The ratio of the area of CeO.sub.2 (100) exposed crystal face to the area of CeO.sub.2 total exposed crystal face is obtained by collecting HAADF-STEM morphology photo of a catalyst sample and calculation, i.e. it is a ratio of the observed area of the CeO.sub.2 (100) crystal face to the observed area of CeO.sub.2 total exposed crystal face. The area of CeO.sub.2 total exposed crystal face is the total area of the exposed crystal faces CeO.sub.2 (100), CeO.sub.2 (110), CeO.sub.2 (111) and CeO.sub.2 (311). By observing the exposed crystal face of CeO.sub.2 (100) with a scanning transmission electron microscope, two mutually perpendicular directions and can be seen in the plane perpendicular to the observation direction, and their interplanar distances are both 260-290 pm, proving the exposed crystal face is CeO.sub.2 (100).

[0102] In the present invention, the H.sub.2-TPR experiment of the catalyst is carried out with an AutoChem II 2920 chemical adsorption instrument. 0.1 g of the catalyst is weighed and placed in a U-shaped quartz reaction tube. It is first purged with a 30 mL/min high-purity Ar gas flow at 200 C. for 2 hours. Then hydrogen gas is used as the reducing gas, and argon gas is used as the balance gas. A mixed gas of 10% H.sub.2/Ar is introduced at a rate of 30 mL/min. The system is heated to a certain temperature at 10K/min. The H.sub.2 consumption during the heating process is recorded with a TCD detector. The H.sub.2-TPR main reduction peak position is the temperature position corresponding to the most intense peak of the signals in the spectrum.

[0103] In the present invention, the catalyst of the present invention is evaluated for the ethylbenzene dehydrogenation performance in an isothermal fixed bed. The process is briefly described as follows:

[0104] The reactor is a stainless steel tube with an inner diameter of 1, filled with 50-150 mL of catalyst with a diameter of 3-10 mm. Deionized water and ethylbenzene are respectively input into a preheating mixer through a metering pump. They are preheated and mixed into a gaseous state before entering the reactor. The reactor is heated by an electric heating wire to reach a predetermined temperature. The reaction substance leaving the reactor is condensed by water and analyzed by gas chromatography.

[0105] The ethylbenzene conversion rate and the styrene selectivity are calculated according to the following equations:

Ethylbenzene conversion rate (%)=[ethylbenzene concentration before the reaction(wt %)ethylbenzene concentration after the reaction(wt %)]/ethylbenzene concentration before the reaction(wt %)100%,

Styrene selectivity (%)=the concentration of the formed styrene(wt %)/[ethylbenzene concentration before the reaction(wt %)ethylbenzene concentration after the reaction(wt %)]100%.

Example 1

[0106] Iron oxide red equivalent to 50.1 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 21.4 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 10.5 parts of CeO.sub.2, ammonium molybdate equivalent to 2.8 parts of MoO.sub.3, 3.2 parts of calcium oxide and 3.05 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 0.8 parts of Na.sub.2O and KOH equivalent to 11.2 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 3.2 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0107] The presence of K and Fe in the catalyst of Example 1 in the ratio of K.sub.1.81Fe.sub.10.73O.sub.17 was determined based on the XRD crystal phase analysis.

[0108] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1, and the test results after the 1000-hours reaction are listed in Table 2.

Example 2

[0109] Iron oxide red equivalent to 36.2 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 26.6 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 11.6 parts of CeO.sub.2, ammonium molybdate equivalent to 4.8 parts of MoO.sub.3, 5.4 parts of calcium oxide and 2.6 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 1.8 parts of Na.sub.2O and KOH equivalent to 13.6 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 6.5 mol/L. The mixture was left in the autoclave to stand for reacting at 120 C. for 48 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0110] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1.

Example 3

[0111] Iron oxide red equivalent to 45.6 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 23.8 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 13.8 parts of CeO.sub.2, ammonium molybdate equivalent to 3.6 parts of MoO.sub.3 and 1.5 parts of calcium oxide were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 0.9 parts of Na.sub.2O and KOH equivalent to 10.8 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 2.5 mol/L. The mixture was left in the autoclave to stand for reacting at 170 C. for 12 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0112] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1.

Example 4

[0113] Iron oxide red equivalent to 48.2 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 34.9 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 8.3 parts of CeO.sub.2, ammonium molybdate equivalent to 1.2 parts of MoO.sub.3, 0.4 parts of calcium oxide and 4.8 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 0.8 parts of Na.sub.2O and KOH equivalent to 6.2 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 2.0 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 600 C. for 4 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0114] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1.

Example 5

[0115] Iron oxide red equivalent to 52.3 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 28.0 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 8.1 parts of CeO.sub.2, ammonium molybdate equivalent to 0.6 parts of MoO.sub.3, 2.6 parts of calcium oxide and 2.5 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 1.0 parts of Na.sub.2O and KOH equivalent to 7.4 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 2.6 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 750 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0116] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1.

Example 6

[0117] Iron oxide red equivalent to 50.6 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 20.3 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 6.9 parts of CeO.sub.2, ammonium molybdate equivalent to 3.5 parts of MoO.sub.3, 6.9 parts of calcium oxide, 0.06 parts of titanium oxide and 2.6 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 0.6 parts of Na.sub.2O and KOH equivalent to 11.14 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 3.1 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 980 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0118] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1.

Example 7

[0119] Iron oxide red equivalent to 54.4 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 16.0 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 11.2 parts of CeO.sub.2, 3.0 parts of MoO.sub.3, calcium carbonate equivalent to 3.2 parts of CaO and 3.1 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 1.6 parts of Na.sub.2O and KOH equivalent to 10.6 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 3.0 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 50 C. for 12 hrs and at 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0120] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1. The test results after the 1000-hours reaction are listed in Table 2.

Example 8

[0121] Iron oxide red equivalent to 37.5 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 35.1 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 11.9 parts of CeO.sub.2, ammonium molybdate equivalent to 2.1 parts of MoO.sub.3, calcium nitrate equivalent to 3.3 parts of CaO and 3.5 parts of activated carbon were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 1.5 parts of Na.sub.2O and KOH equivalent to 8.6 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 2.8 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 100 C. for 4 hrs and at 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0122] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1.

Example 9

[0123] Iron oxide red equivalent to 40.0 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 32.5 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 10.6 parts of CeO.sub.2, ammonium molybdate equivalent to 2.1 parts of MoO.sub.3, calcium chloride equivalent to 2.9 parts of CaO and 3.2 parts of graphite were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 0.5 parts of Na.sub.2O and KOH equivalent to 11.4 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 3.5 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 120 C. for 4 hrs and at 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0124] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1.

Example 10

[0125] Iron oxide red equivalent to 50.5 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 19.7 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 12.0 parts of CeO.sub.2, 2.6 parts of MoO.sub.3, 3.5 parts of calcium oxide and 3.2 parts of hydroxymethylcellulose were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 1.1 parts of Na.sub.2O and KOH equivalent to 10.6 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 3.4 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and at 180 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0126] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1.

Example 11

[0127] Iron oxide red equivalent to 50.9 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 23.4 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 11.2 parts of CeO.sub.2, ammonium molybdate equivalent to 1.8 parts of MoO.sub.3, calcium carbonate equivalent to 2.7 parts of CaO and 3.2 parts of graphite were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 0.5 parts of Na.sub.2O and KOH equivalent to 9.5 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 2.9 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and at 200 C. for 2 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0128] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1.

Example 12

[0129] Iron oxide red equivalent to 50.1 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 21.4 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 10.5 parts of CeO.sub.2, potassium nitrate equivalent to 9.6 parts of K.sub.2O, ammonium molybdate equivalent to 2.8 parts of MoO.sub.3, 3.2 parts of calcium oxide and 3.05 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 0.8 parts of Na.sub.2O and KOH equivalent to 1.6 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 3.2 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0130] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1.

[0131] The test results after the 1000-hours reaction are listed in Table 2.

Example 13

[0132] Iron oxide red equivalent to 50.1 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 21.4 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 10.5 parts of CeO.sub.2, potassium carbonate equivalent to 11.2 parts of K.sub.2O, ammonium molybdate equivalent to 2.8 parts of MoO.sub.3, 3.2 parts of calcium oxide and 3.05 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then an aqueous solution of NaOH equivalent to 0.8 parts of Na.sub.2O was added, and the OH concentration in the aqueous solution was 3.2 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0133] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1.

Example 14

[0134] Iron oxide red equivalent to 50.1 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 21.4 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 10.5 parts of CeO.sub.2, ammonium molybdate equivalent to 2.8 parts of MoO.sub.3, 3.2 parts of calcium oxide, sodium nitrate equivalent to 0.8 parts of Na.sub.2O, and 3.05 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then an aqueous solution of KOH equivalent to 11.2 parts of K.sub.2O was added, and the OH concentration in the aqueous solution was 3.2 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0135] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1, and the test results after the 1000-hours reaction are listed in Table 2.

Example 15

[0136] Iron oxide red equivalent to 50.1 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 21.4 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 10.5 parts of CeO.sub.2, ammonium molybdate equivalent to 2.8 parts of MoO.sub.3, 3.2 parts of calcium oxide and 3.05 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then an aqueous solution of KOH equivalent to 11.2 parts of K.sub.2O was added, and the OH concentration in the aqueous solution was 3.2 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0137] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1.

Comparative Example 1

[0138] Iron oxide red equivalent to 50.1 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 21.4 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 10.5 parts of CeO.sub.2, potassium carbonate equivalent to 11.2 parts of K.sub.2O, ammonium molybdate equivalent to 2.8 parts of MoO.sub.3, 4.0 parts of calcium oxide and 3.05 parts of polystyrene microspheres were weighed and added together with the same amount of water as in Example 1 to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. The concentration of hydroxy groups in the mixed aqueous solution was 0.3 mol/L. The mixture was left in the autoclave to stand at 140 C. for 20 hrs. Then, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The catalyst evaluation method was the same as that in Example 1. The test result and the catalyst composition are listed in Tables 1 and 2.

Comparative Example 2

[0139] Iron oxide red equivalent to 39.6 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 21.4 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 21.0 parts of CeO.sub.2, ammonium molybdate equivalent to 2.8 parts of MoO.sub.3, 3.2 parts of calcium oxide and 3.05 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 0.8 parts of Na.sub.2O and KOH equivalent to 11.2 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 3.2 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0140] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1, and the test results after the 1000-hours reaction are listed in Table 2.

Comparative Example 3

[0141] Iron oxide yellow equivalent to 71.5 parts of Fe.sub.2O.sub.3 was weighed and mixed with an aqueous solution of cerium nitrate equivalent to 10.5 parts of CeO.sub.2, and then mixed with an aqueous solution of KOH equivalent to 11.2 parts of K.sub.2O, and the OH concentration in the mixed aqueous solution was 1.5 mol/L. The resulting paste was dried at 150 C. for 2 hours and then calcined at 850 C. for 2 hours. The calcined product was ground, and then mixed with an aqueous suspension of 2.8 parts of MoO.sub.3, 3.2 parts of calcium oxide, sodium carbonate equivalent to 0.8 parts of Na.sub.2O and 3.05 parts of polystyrene microspheres, extruded into strips and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0142] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1, and the test results after the 1000-hours reaction are listed in Table 2.

Comparative Example 4

[0143] Iron oxide red equivalent to 50.1 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 21.4 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 10.5 parts of CeO.sub.2, potassium carbonate equivalent to 10.64 parts of K.sub.2O, NaOH equivalent to 0.8 parts of Na.sub.2O, ammonium molybdate equivalent to 2.8 parts of MoO.sub.3, 3.2 parts of calcium oxide and 3.05 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then deionized water was added, the resulting mixture was stirred for another 0.5 hours, extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 800 C. for 4 hrs to produce a semi-finished catalyst. Then potassium carbonate equivalent to 0.56 parts of K.sub.2O was dissolved in water, the semi-finished catalyst was impregnated in this solution with the OH concentration of 0.1 mol/L for 2 hours, and then placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0144] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1, and the test results after the 1000-hours reaction are listed in Table 2.

Comparative Example 5

[0145] Iron oxide red equivalent to 47.1 parts of Fe.sub.2O.sub.3, iron oxide yellow equivalent to 21.4 parts of Fe.sub.2O.sub.3, cerium nitrate equivalent to 10.5 parts of CeO.sub.2, praseodymium nitrate equivalent to 3.0 parts of Pr.sub.2O.sub.3, ammonium molybdate equivalent to 2.8 parts of MoO.sub.3, 3.2 parts of calcium oxide and 3.05 parts of polystyrene microspheres were weighed and added to a mixer, and the resulting mixture was stirred for 2 hours until evenly mixed. Then a mixed aqueous solution of NaOH equivalent to 0.8 parts of Na.sub.2O and KOH equivalent to 11.2 parts of K.sub.2O was added, and the OH concentration in the mixed aqueous solution was 3.2 mol/L. The mixture was left in the autoclave to stand for reacting at 140 C. for 20 hrs. Then, after adjusting the water content, the above mixture was extruded and pelletized to obtain pellets with a diameter of 3 mm and a length of 6 mm, which were placed in an oven and dried at 80 C. for 4 hrs and 150 C. for 4 hrs, then placed in a muffle furnace and calcined at 650 C. for 2 hrs and at 900 C. for 2 hrs to obtain a finished catalyst. The composition of the catalyst is shown in Table 1.

[0146] 100 mL of the catalyst was put into a reactor for performance evaluation under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 0.8 (wt). The test results after the 100-hours reaction are listed in Table 1, and the test results after the 1000-hours reaction are listed in Table 2.

TABLE-US-00001 TABLE 1 Catalyst compositions, properties and evaluation results of Examples and Comparative Examples H.sub.2-TPR Ethylbenzene Styrene Catalyst Catalyst Composition (parts) Ratio main peak conversion selectivity No. Fe.sub.2O.sub.3 K.sub.2O CeO.sub.2 MoO.sub.3 CaO Na.sub.2O TiO.sub.2 **(%) position( C.) rate *(%) *(%) Ex. 1 71.5 11.2 10.5 2.8 3.2 0.8 78 576 76.1 96.5 Ex. 2 62.8 13.6 11.6 4.8 5.4 1.8 80 582 76.7 95.9 Ex. 3 69.4 10.8 13.8 3.6 1.5 0.9 76 575 75.8 96.2 Ex. 4 83.1 6.2 8.3 1.2 0.4 0.8 72 571 75.4 96.8 Ex. 5 80.3 7.4 8.1 0.6 2.6 1.0 74 573 75.6 96.7 Ex. 6 70.9 11.14 6.9 3.5 6.9 0.6 0.06 77 575 75.9 96.6 Ex. 7 70.4 10.6 11.2 3.0 3.2 1.6 75 574 75.7 96.5 Ex. 8 72.6 8.6 11.9 2.1 3.3 1.5 74 572 75.5 96.6 Ex. 9 72.5 11.4 10.6 2.1 2.9 0.5 79 579 76.3 96.4 Ex. 10 70.2 10.6 12.0 2.6 3.5 1.1 77 576 76.0 96.3 Ex. 11 74.3 9.5 11.2 1.8 2.7 0.5 75 574 75.8 96.5 Ex. 12 71.5 11.2 10.5 2.8 3.2 0.8 74 573 75.7 96.4 Ex. 13 71.5 11.2 10.5 2.8 3.2 0.8 67 570 75.0 96.7 Ex. 14 71.5 11.2 10.5 2.8 3.2 0.8 70 571 75.2 96.2 Ex. 15 71.5 11.2 10.5 2.8 3.2 77 575 75.6 95.5 Comp. 1 71.5 11.2 10.5 2.8 4.0 16 545 72.7 96.4 Comp. 2 61.0 11.2 21.0 2.8 3.2 0.8 14 541 67.3 91.2 Comp. 3 71.5 11.2 10.5 2.8 3.2 0.8 18 546 72.8 95.5 Comp. 4 71.5 11.2 10.5 2.8 3.2 0.8 16 544 70.4 96.5 Comp. 5*** 68.5 11.2 10.5 2.8 3.2 0.8 37 553 73.0 95.1 Note: Ex.: Example; Comp.: Comparative Example *Ethylbenzene conversion rate and styrene selectivity for 100-hours reaction at steam/ethylbenzene ratio of 0.8; **Ratio: the ratio of the area of CeO.sub.2 (100) exposed crystal face to the area of CeO.sub.2 total exposed crystal face of the catalyst; ***Catalyst also contained 3.0 parts of Pr.sub.2O.sub.3.

TABLE-US-00002 TABLE 2 Catalyst stability evaluation results of Examples and Comparative Examples Catalyst 100-hours 1000-hours No. reaction reaction Ex. 1 Ethylbenzene conversion rate (%) 76.1 74.1 Styrene selectivity (%) 96.5 96.6 Ex. 7 Ethylbenzene conversion rate (%) 75.7 73.6 Styrene selectivity (%) 96.5 96.7 Ex. 12 Ethylbenzene conversion rate (%) 75.7 73.7 Styrene selectivity (%) 96.4 96.5 Ex. 14 Ethylbenzene conversion rate (%) 75.2 72.5 Styrene selectivity (%) 96.2 96.4 Comp. 1 Ethylbenzene conversion rate (%) 72.7 69.2 Styrene selectivity (%) 96.4 96.5 Comp. 4 Ethylbenzene conversion rate (%) 70.4 66.3 Styrene selectivity (%) 96.5 96.5

[0147] 100 mL of the catalyst was put into a reactor, and the performance evaluation was performed under the conditions of an absolute pressure of 70 kPa, a liquid hourly space velocity of 1.0 h.sup.1, a temperature of 620 C., and a steam/ethylbenzene ratio of 2 (wt). The test results after the 100-hours reaction are listed in Table 3.

TABLE-US-00003 TABLE 3 Performance evaluation result of the catalyst of Example 1 under the condition of a steam/ethylbenzene ratio of 2 (wt) 100-hours reaction Ethylbenzene conversion rate (%) 85.2 Styrene selectivity (%) 97.6

[0148] It can be seen from FIGS. 1, 2 and 3 that the main exposed crystal face of CeO.sub.2 in the catalyst of Example 1 was the CeO.sub.2 (100) crystal face. The main exposed crystal face of CeO.sub.2 in the catalyst of Comparative Example 1 was the CeO.sub.2 (111) crystal face, and the CeO.sub.2 (111) crystal face comprised 52% of the total exposed crystal face of CeO.sub.2. The H.sub.2-TPR main reduction peak position of the catalyst of Example 1 was 576 C., which is significantly higher than the H.sub.2-TPR main reduction peak position of the catalyst of Comparative Example 1, which was 545 C. Combining the results in Table 1 and Table 2, it can be seen that the catalysts of the present invention had high activity and good stability. After the dehydrogenation reaction had been run for a long time of 1000 hours, the ethylbenzene conversion rate did not significantly decrease.

[0149] The preferred embodiments of the present invention have been described in detail above, but the present invention is not limited thereto. Within the scope of the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, including the combination of various technical features in any other suitable manner. These simple modifications and combinations should also be regarded as the disclosed content of the present invention and all belong to the protection scope of the present invention.