Catalyst for the oxidative dehydrogenation of butene to butadiene and preparation process thereof

Abstract

The present disclosure provides a catalyst for oxidative dehydrogenation of butene to butadiene, comprising at least one compound of formula Zn.sub.aAl.sub.bM.sub.cFe.sub.eO.sub.f.Z(-Fe.sub.2O.sub.3), wherein M is at least one element chosen from Be, Mg, Ca, Sr, Mn, Ba, Cu, Co, and Ni, Z represents the percentage by weight of -Fe2O3 in the catalyst and ranges from 10% to 70%. Also provided herein is a process of preparing said catalyst and the use of said catalyst in an oxidative dehydrogenation of butene to butadiene processes.

Claims

1. A catalyst for the oxidative dehydrogenation of butene to butadiene comprising at least one compound of formula Zn.sub.aAl.sub.bM.sub.cFe.sub.eO.sub.f.Z(-Fe.sub.2O.sub.3), wherein M is at least one element chosen from Be, Mg, Ca, Sr, Mn, Ba, Cu, Co, and Ni; Z is the percentage by weight of -Fe.sub.2O.sub.3 in the catalyst, ranging from 10% to 70%; wherein b is 1, a ranges from 0 to 10, c is larger than zero and less than or equal to 4, e ranges from 3 to 25, f is greater than 4.5 and equal to or less than 48; and further wherein 2a+3b+2c+3e=2f.

2. The catalyst according to claim 1, wherein the catalyst comprises a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase, and the specific surface area of the catalyst ranges from 1 m.sup.2/g to 80 m.sup.2/g.

3. The catalyst according to claim 1, wherein M is at least two elements chosen from Be, Mg, Ca, Sr, Mn, Ba, Cu, Co, and Ni.

4. The catalyst according to claim 1, wherein a is not zero.

5. The catalyst according to claim 1, wherein e ranges from 3 to 20.

6. The catalyst according to claim 1, wherein temperature programmed desorption spectrum of ammonia probe molecules from said catalyst comprises a characteristic peak at desorption temperatures of 340 C. to 400 C. and full width at half maximum of 60 C. to 100 C.

7. The catalyst according to the claim 6, wherein the temperature programmed desorption spectrum of ammonia probe molecules from said catalyst further comprises (i) a characteristic peak at desorption temperatures of 170 C. to 210 C. and full width at half maximum of 70 C. to 100 C., and (ii) a characteristic peak at desorption temperatures of 260 C. to 300 C. and full width at half maximum of 40 C. to 70 C.

8. A process for preparing the catalyst according to claim 1, comprising: (1) preparing a salt solution comprising Al, M, and Fe, and optionally the element of Zn, (2) adding a base solution to the salt solution to obtain a pH value ranging from 8 to 12, and (3) aging, drying and calcining the precipitate obtained from (2).

9. The process according to claim 8, comprising: an aging temperature ranging from 5 C. to 80 C., an aging time ranging from 0.5 hour to 48 hours, a calcination temperature ranging from 500 C. to 900 C., and a calcination time ranging from 3 hours to 72 hours.

10. A process for the oxidative dehydrogenation of butene to butadiene comprising: adding the catalyst prepared by the process according to claim 8 into oxidative dehydrogenation reaction of butene to butadiene, with butene, oxygen-containing gas, and water vapor.

11. The process according to claim 10, wherein the reaction is carried out at a temperature ranging from 300 C. to 500 C., a space velocity ranging from 200 h.sup.1 to 500 h.sup.1, a molar ratio of oxygen-butene ranging from 0.6:1 to 0.9:1, and a molar ratio of water-butene ranging from 6:1 to 20:1.

12. A process for the oxidative dehydrogenation of butene to butadiene comprising: adding the catalyst according to claim 1 into oxidative dehydrogenation reaction of butene to butadiene, with butene, oxygen-containing gas, and water vapor.

13. The process according to claim 12, wherein the reaction is carried out at a temperature ranging from 300 C. to 500 C., a space velocity ranging from 200 h.sup.1 to 500 h.sup.1, a molar ratio of oxygen-butene ranging from 0.6:1 to 0.9:1, and a molar ratio of water-butene ranging from 6:1 to 20:1.

Description

BRIEF DESCRIPTION OF DRAWINGS

(1) FIG. 1 shows the temperature programmed desorption spectrum of the ammonia probe molecules of the catalysts in Example 1 and Comparative Example 1 of the present disclosure.

EXAMPLES

(2) The following examples further explain the present disclosure. It should be noted that in the embodiments described below, in Table 1, the corresponding Z value was measured with XRD.

Example 1

(3) Catalyst preparation: 5.13 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 7.51 g of Al(NO.sub.3).sub.3.9H.sub.2O, 14.88 g of Zn(NO.sub.3).sub.2.6H.sub.2O, and 212.52 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 500 ml of distilled water. NaOH solution (3M) was added dropwise under quick stirring to obtain a pH value of 9.3 during the precipitation. The resulting precipitate was heated for 90 minutes at 65 C. under stirring for it to be aged, stood at room temperature for 12 hours, and then filtered. The resulting filter cake was then washed with distilled water, dried at 120 C. for 24 hours, and then placed into a muffle furnace with a furnace temperature of 700 C. and calcined for 6 hours. The resulting catalyst is denoted by A.

(4) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicate that the catalyst contains a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase; and the temperature programmed desorption test of ammonia shows that there are enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 12 m.sup.2/g. FIG. 1 contains the Temperature-Programmed Desorption (TPD) spectrum of ammonia from the catalyst prepared in Example 1. The characteristic peak and full width at the half maximum (FWHM) shown in the TPD spectrum can be used to characterize the acid sites of the catalyst. As FIG. 1 shows, there are three ammonia desorption peaks on the TPD spectrum of the catalyst in Example 1, i.e., at desorption temperatures of 170210 C., FWHM of 70100 C.; desorption temperatures of 260300 C., FWHM of 4070 C.; and desorption temperatures of 340400 C., FWHM of 60100 C., respectively.

(5) Catalyst evaluation: The catalyst was crushed, screened (taking the ones with 20-40 meshes), and activated for 1 hour with air in a fixed bed reactor at 470 C. After being cooled, the catalyst was used to catalyze the oxidative dehydrogenation reaction of butene to butadiene at a temperature of 360 C., a space velocity of 350 h.sup.1, a molar ratio of oxygen-butene of 0.75:1, and a molar ratio of water-butene of 10:1. The yield per pass of butadiene was 80.1%, the conversion per pass of butene was 85.9% and the selectivity of butadiene was 91.3%.

Example 2

(6) Catalyst preparation: 5.13 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 15.00 g of Al(NO.sub.3).sub.3.9H.sub.2O, 5.95 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 264.71 g of Fe(NO.sub.3).sub.3.9H.sub.2O were weighed, and the preparation process of the catalyst was the same as that in Example 1. The resulting catalyst is denoted by B.

(7) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 25 m.sup.2/g.

(8) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 78.1%, the conversion per pass of butene was 83.3%, and the selectivity of butadiene was 93.8%.

Example 3

(9) Catalyst preparation: Taking 3.85 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 3.76 g of Al(NO.sub.3).sub.3.9H.sub.2O, 20.84 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 180.58 g of Fe(NO.sub.3).sub.3.9H.sub.2O were weighed, and the preparation process of the catalyst was the same as that in Example 1. The resulting catalyst is denoted by C.

(10) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 9 m.sup.2/g.

(11) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 79.4%, the conversion per pass of butene was 84.6%, and the selectivity of butadiene was 93.8%.

Example 4

(12) Catalyst preparation; 5.13 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 7.51 g of Al(NO.sub.3).sub.3.9H.sub.2O, 14.88 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 112.48 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 250 ml of distilled water, and the preparation process of the catalyst was the same as that in Example 1. The resulting catalyst is denoted by D.

(13) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 21 m.sup.2/g.

(14) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 78.8%, the conversion per pass of butene was 84.1%, and the selectivity of butadiene was 93.7%.

Example 5

(15) Catalyst preparation: 2.57 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 1.81 g of Cu(NO.sub.3).sub.2.3H.sub.2O, 18.77 g of Al(NO.sub.3).sub.3.9H.sub.2O, 4.46 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 146.33 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water. NaOH solution (1M) was added dropwise under quick stirring to obtain a pH value of 9.0 at the end of the precipitation. The remaining steps were the same as those in Example 1. The resulting catalyst is denoted by E.

(16) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 30 m.sup.2/g.

(17) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 79.0%, the conversion per pass of butene was 82.9%, and the selectivity of butadiene was 95.3%.

Example 6

(18) Catalyst preparation: 2.56 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 1.74 g of Ni(NO.sub.3).sub.2.6H.sub.2O, 15.01 g of Al(NO.sub.3).sub.3.9H.sub.2O, 7.14 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 153.42 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water. NaOH solution (3M) was added dropwise to the metal ion solution to keep the pH at 9.2. The remaining steps were the same as those in Example 1. The resulting catalyst is denoted by F.

(19) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 16 m.sup.2/g.

(20) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 83.8%, the conversion per pass of butene was 87.4%, and the selectivity of butadiene was 95.9%.

Example 7

(21) Catalyst preparation: 2.54 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 2.09 g of Ba(NO.sub.3).sub.2, 14.25 g of Al(NO.sub.3).sub.3.9H.sub.2O, 7.44 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 162.71 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water to prepare a metal ion solution, and said metal ion solution was added dropwise into 400 ml of NaOH solution (3M) contained in a beaker under quick stirring so as to obtain a pH value of 9.5 at the end of the precipitation. The remaining steps were the same as those in Example 1, and the resulting catalyst is denoted by G.

(22) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 17 m.sup.2/g.

(23) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 78.8%, the conversion per pass of butene was 82.2%, and the selectivity of butadiene was 95.9%.

Example 8

(24) Catalyst preparation: 3.84 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 2.54 g of Sr(NO.sub.3).sub.2, 12.75 g of Al(NO.sub.3).sub.3.9H.sub.2O, 6.54 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 158.63 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water to prepare a metal ion solution. NaOH solution (3M) was added dropwise to the metal ion solution under quick stirring to obtain a pH value of 8.3 at the end of the precipitation. The remaining steps were the same as those in Example 1. The resulting catalyst is denoted by H.

(25) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 34 m.sup.2/g.

(26) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 82.6%, the conversion per pass of butene was 85.7%, and the selectivity of butadiene was 96.4%.

Example 9

(27) Catalyst preparation: 2.55 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 2.90 g of Co(NO.sub.3).sub.2.6H.sub.2O, 14.25 g of Al(NO.sub.3).sub.3.9H.sub.2O, 6.89 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 161.78 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water to prepare a metal ion solution. NaOH solution (3M) was added dropwise to the metal ion solution under quick stirring to obtain a pH value of 11.0 at the end of the precipitation. The remaining steps were the same as those in Example 1 and the resulting catalyst is denoted by I.

(28) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 42 m.sup.2/g.

(29) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 82.7%, the conversion per pass of butene was 86.1%, and the selectivity of butadiene was 96.0%.

Example 10

(30) Catalyst preparation: 9.49 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 3.75 g of Al(NO.sub.3).sub.3.9H.sub.2O, 7.44 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 71.25 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water to prepare a metal ion solution. NaOH solution (3M) was added dropwise to the metal ion solution under quick stirring. The pH value at the end of the precipitation was 9.3. The precipitate was heated for 60 minutes at 65 C. under stirring for it to be aged, and the remaining steps were the same as those Example 1. The resulting catalyst is denoted by J.

(31) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 22 m.sup.2/g.

(32) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 79.0%, the conversion per pass of butene was 85.3%, and the selectivity of butadiene was 92.6%.

(33) Catalyst preparation: 2.42 g of Cu(NO.sub.3).sub.2.3H.sub.2O, 2.33 g of Ni(NO.sub.3).sub.2.6H.sub.2O, 14.25 g of Al(NO.sub.2).sub.3.9H.sub.2O, 7.44 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 12.5.62 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water to prepare a metal ion solution. NaOH solution (3M) was added dropwise to the metal ion solution under quick stirring to obtain a pH value of 8.6 at the end of the precipitation. The resulting precipitate was heated for 30 minutes at 65 C. under stirring for it to be aged, and the remaining steps were the same as those in Example 1. The resulting catalyst is denoted by K.

(34) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 29 m.sup.2/g.

(35) The resulting catalyst was analyzed by an ICP-AES inductively coupled plasma emission spectrometer, and the results are as follows: Cu: 2.06 wt %, Ni: 1.95 wt %, Al: 3.41 wt %, Zn: 5.27 wt %, Fe: 57.8 wt %.

(36) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 81.7%, the conversion per pass of butene was 85.7%, and the selectivity of butadiene was 95.3%.

Example 12

(37) Catalyst preparation: 2.42 g of Cu(NO.sub.3).sub.2.3H.sub.2O, 2.74 g of Ba(NO.sub.3).sub.2, 9.38 g of Al(NO.sub.3).sub.3.9H.sub.2O, 7.14 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 167.53 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water to prepare a metal ion solution. NaOH solution (3M) was added dropwise to the metal ion solution under quick stirring to obtain a pH value of 9.8 at the end of precipitation. The resulting precipitate was heated for 90 minutes at 65 C. under stirring for it to be aged, stood at room temperature for 24 hours, and then filtered. The resulting filter cake was washed with distilled water, and the remaining steps were the same as those in Example 1. The resulting catalyst is denoted by L.

(38) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 36 m.sup.2/g.

(39) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 83.0%, the conversion per pass of butene was 85.8%, and the selectivity of butadiene was 96.7%.

Example 13

(40) Catalyst preparation: 3.49 g of Co(NO.sub.3).sub.2.6H.sub.2O, 3.34 g of Ni(NO.sub.3).sub.2.6H.sub.2O, 11.63 g of Al(NO.sub.3).sub.3.9H.sub.2O, 8.92 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 167.22 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water to prepare a metal ion solution. NaOH solution (3M) was added dropwise to the metal ion solution under quick stirring to obtain a pH value of 9.5 at the end of the precipitation. The resulting precipitate was heated for 90 minutes at 65 C. under stirring for it to be aged, stood at room temperature for 12 hours, and then filtered. The resulting filter cake was washed with distilled water. After being dried at 120 C. for 24 hours, the filter cake was placed into a muffle furnace with a furnace temperature of 650 C. and calcined for 6 hours. The remaining steps are the same as those in Example 1. The resulting catalyst is denoted by M.

(41) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained spinel crystal a phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 27 m.sup.2/g.

(42) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 83.2%, the conversion per pass of butene was 85.3%, and the selectivity of butadiene was 97.5%.

Example 14

(43) Catalyst preparation: 4.72 g of Ca(NO.sub.3).sub.2.4H.sub.2O, 10.87 g of Cu(NO.sub.3).sub.2.3H.sub.2O, 7.50 g of Al(NO.sub.3).sub.3.9H.sub.2O, 7.73 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 188.21 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water to prepare a metal ion solution. NaOH solution (3M) was added dropwise to the metal ion solution under quick stirring to obtain a pH value of 9.3 at the end of the precipitation. The precipitate was heated for 90 minutes at 65 C. under stirring for it to be aged, stood at room temperature for 12 hours, and then filtered. The resulting filter cake was washed with distilled water. After being dried at 120 C. for 24 hours, the filter cake was placed into a muffle furnace with a furnace temperature of 650 C. and calcined for 10 hours. The remaining steps are the same as those in Example 1. The resulting catalyst is denoted by N.

(44) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 26 m.sup.2/g.

(45) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 82.6%, the conversion per pass of butene was 86.9%, and the selectivity of butadiene was 95.1%.

Example 15

(46) Catalyst preparation: 5.13 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 2.81 g of Be(NO.sub.3).sub.2.3H.sub.2O, 9.38 g of Al(NO.sub.3).sub.3.9H.sub.2O, 7.14 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 158.60 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water to prepare a metal ion solution. Ammonia solution (15 wt %) was added dropwise to the metal ion solution under quick stirring to obtain a pH value of 10.5 at the end of the precipitation. The remaining steps were the same as those in Example 1, and the resulting catalyst is denoted by O.

(47) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 16 m.sup.2/g.

(48) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 79.2%, the conversion per pass of butene was 84.1%, and the selectivity of butadiene was 94.2%.

Example 16

(49) Catalyst preparation: 6.41 g of Mg(NO.sub.3).sub.2.6H.sub.2), 18.76 g of Al(NO.sub.3).sub.3.9H.sub.2O and 163.67 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water to prepare a metal ion solution, and the remaining steps were the same as those in Example 1. The resulting catalyst is denoted by P.

(50) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 28 m.sup.2/g.

(51) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 76.9%, the conversion per pass of butene was 82.2%, and the selectivity of butadiene was 93.5%.

Example 17

(52) Catalyst preparation: 4.73 g of Ca(NO.sub.3).sub.2.4H.sub.2O, 2.56 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 7.50 g of Al(NO.sub.3).sub.3.9H.sub.2O, 11.90 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 231.45 g of Fe(NO.sub.3).sub.3.9H.sub.2O were weighed, and the remaining steps were the same as those in Example 1. The resulting catalyst is denoted by Q.

(53) The composition and acid sites of the catalyst are show en in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 32 m.sup.2/g.

(54) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 81.9%, the conversion per pass of butene was 85.1%, and the selectivity of butadiene was 96.2%.

Example 18

(55) Catalyst preparation: 2.50 g of Mn(NO.sub.3).sub.2.4H.sub.2O, 7.69 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 15.00 g of Al(NO.sub.3).sub.3.9H.sub.2O and 237.78 g of Fe(NO.sub.3).sub.3.9H.sub.2O were weighed, and the remaining steps were the same as those in Example 1. The resulting catalyst is denoted by R.

(56) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 41 m.sup.2/g.

(57) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 77.6%, the conversion per pass of butene was 81.9%, and the selectivity of butadiene was 94.7%.

Example 19

(58) Catalyst preparation: 1.45 g of Ni(NO.sub.3).sub.2.6H.sub.2O, 1.46 g of Co(NO.sub.3).sub.2.6H.sub.2O, 3.85 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 11.25 g of Al(NO.sub.3).sub.3.9H.sub.2O, 8.92 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 175.11 g of Fe(NO.sub.3).sub.3.9H.sub.2O were weighed, and the remaining steps were the same as those in Example 1. The resulting catalyst is denoted by S.

(59) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 20 m.sup.2/g.

(60) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 80.4%, the conversion per pass of butene was 84.7%, and the selectivity of butadiene was 94.9%.

(61) TABLE-US-00001 TABLE 1 Element a b c e f Catalyst M (or a) (or b) (or c) (or 2) (or 4) Z Example 1: A Mg 2.50 1.00 1.00 10.00 20.00 54.3% Example 2: B Mg 0.50 1.00 0.50 5.00 10.00 64.0% Example 3: C Mg 7.00 1.00 1.50 20.00 40.00 46.4% Example 4: D Mg 2.50 1.00 1.00 10.00 20.00 22.3% Example5: E Mg, Cu 0.30 1.00 0.35 4.00 8.15 38.4% Example 6: F Mg, Ni 0.60 1.00 0.40 5.00 10.00 40.8% Example 7: G Mg, Ba 0.66 1.00 0.47 5.26 10.53 42.9% Example 8: H Mg, Sr 0.65 1.00 0.79 5.88 11.76 41.9% Example 9: I Mg, Co 0.61 1.00 0.53 5.26 10.53 43.3% Example 10: J Mg 2.50 1.00 3.70 3.00 12.20 64.5% Example 11: K Cu, Ni 0.66 1.00 0.47 5.26 10.52 29.4% Example 12: L Cu, Ba 0.96 1.00 0.82 8.00 15.28 44.2% Example 13: M Co, Ni 0.97 1.00 0.76 6.45 12.90 44.0% Example 14: N Ca, Cu 1.30 1.00 3.25 10.00 21.05 47.1% Example 15: O Mg, Be 0.96 1.00 1.40 8.00 15.86 43.0% Example 16: P Mg 0 1.00 0.50 4.00 8.00 45.6% Example 17: Q Mg, Ca 2.00 1.00 1.50 10.00 20.00 57.8% Example 18: R Mg, Mn 0 1.00 1.00 5.00 10.00 61.6% Example 19: S Mg, Ni, 1.00 1.00 0.83 6.67 13.33 46.7% Co Comparative Mg 0.60 0 0.40 2.00 4.00 55.5% Example 1 Comparative Cu, Ba 0.60 0 0.40 2.00 4.00 42.8% Example 2

(62) TABLE-US-00002 TABLE 2 Position of NH.sub.3 Desorption peaks (Acid sites) ( C.) Desorption peak 1 Desorption peak 2 Desorption peak 3 (full width at (full width at (full width at Catalyst half maximum) half maximum) half maximum) Example 1 A 188.5 (87.9) 278.8 (56.4) 361.4 (81.6) Example 2 B 186.2 (85.2) 275.2 (61.5) 366.6 (87.3) Example 3 C 176.5 (90.4) 270.4 (54.2) 359.2 (84.5) Example 4 D 195.3 (94.5) 288.8 (58.9) 355.9 (75.8) Example 5 E 190.2 (86.9) 278.0 (50.4) 367.8 (74.4) Example 6 F 202.3 (80.8) 289.4 (57.2) 365.2 (86.5) Example 7 G 184.9 (77.9) 294.3 (63.5) 374.5 (94.6) Example 8 H 178.6 (83.5) 296.1 (55.1) 366.3 (95.2) Example 9 I 186.6 (84.0) 285.9 (57.2) 384.2 (86.7) Example 10 J 192.0 (79.4) 278.2 (50.6) 381.4 (77.4) Example 11 K 175.9 (92.6) 270.5 (48.6) 395.0 (72.0) Example 12 L 188.0 (76.2) 266.1 (59.2) 364.2 (69.4) Example 13 M 194.4 (83.6) 273.5 (66.0) 370.5 (80.5) Example 14 N 186.5 (88.4) 284.6 (57.8) 348.2 (64.2) Example 15 O 181.2 (86.9) 278.6 (48.9) 365.5 (88.0) Example 16 P 195.8 (92.5) 274.5 (56.6) 374.2 (80.3) Example 17 Q 196.4 (84.4) 280.9 (47.8) 369.1 (79.2) Example 18 R 193.4 (76.8) 271.1 (51.6) 365.2 (90.4) Example 19 S 187.9 (85.6) 265.0 (57.0) 366.4 (86.4) Comparative / 189.5 (85.1) 275.8 (58.6) Example 1 Comparative / 187.8 (86.7) 277.3 (59.2) Example 2

Example 20

(63) The catalyst of Example 1 was activated for 1 hour with air in a fixed bed reactor at 470 C. After cooling, the resulting catalyst was used to catalyze the oxidative dehydrogenation reaction of butene to butadiene at a temperature of 340 C., a space velocity of butene of 350 h.sup.1, a molar ratio of oxygen-butene of 0.70:1 and a molar ratio of water-butene of 10:1; the yield per pass of butadiene was 79.2%, the conversion per pass of butene was 82.6%, and the selectivity of butadiene was 95.9%.

Example 21

(64) The catalyst of Example 1 was activated for 1 hour with air in a fixed bed reactor at 470 C. After cooling, the resulting catalyst was used to catalyze the oxidative dehydrogenation reaction of butene to butadiene at a temperature of 380 C., a space velocity of butene of 350 h.sup.1, a molar ratio of oxygen-butene of 0.70:1, and a molar ratio of water-butene of 10:1; the yield per pass of butadiene was 81.8%, the conversion per pass of butene was 87.1%, and the selectivity of butadiene was 93.9%.

Example 22

(65) The catalyst of Example 1 was activated for 1 h with air in a fixed bed reactor at 470 C. After cooling, the resulting catalyst was used to catalyze the oxidative dehydrogenation reaction of butene to butadiene at a temperature of 360 C., a space velocity of butene of 300 h.sup.1, a molar ratio of oxygen-butene of 0.70:1 and a molar ratio of water-butene of 10:1; the yield per pass of butadiene was 79.3%, the conversion per pass of butene was 86.9%, and the selectivity of butadiene was 91.1%.

Example 23

(66) The catalyst of Example 1 was activated for 1 hour with air in a fixed bed reactor at 470 C. After cooling, the resulting catalyst was used to catalyze the oxidative dehydrogenation reaction of butene to butadiene at a temperature of 360 C., a space velocity of butene of 350 h.sup.1, a molar ratio of oxygen-butene of 0.80:1 and a molar ratio of water-butene of 10:1; the yield per pass of butadiene was 82.1%, the conversion per pass of butene was 87.7%, and the selectivity of butadiene was 93.6%.

Example 24

(67) The catalyst of Example 1 was activated for 1 hour with air in a fixed bed reactor at 470 C. After cooling, the resulting catalyst was used to catalyze the oxidative dehydrogenation reaction of butene to butadiene at a temperature of 360 C., a space velocity of butene of 350 h.sup.1, a molar ratio of oxygen-butene of 0.70:1 and a molar ratio of water-butene of 12:1; the yield per pass of butadiene was 80.0%, the conversion per pass of butene was 85.3%, and the selectivity of butadiene was 92.6%.

Example 25

(68) The stability of the catalyst of Example 1 was studied; the evaluation conditions of the catalyst were the same as those in Example 1; and the results are shown in Table 3.

(69) TABLE-US-00003 TABLE 3 Reaction Conversion of Selectivity to time (h) butene (%) butadiene (wt. %) 100 85.9 93.3 3,000 85.8 93.4 6,000 85.6 93.1

(70) As the data in Table 3 shows, when the catalyst of the present disclosure was used to catalyze the oxidative dehydrogenation reaction of butene to butadiene, the catalyst not only provided high catalytic activity and selectivity but also retained high stability, wherein the catalyst life was at least more than 6,000 hours.

Comparative Example 1

(71) Catalyst preparation: 10.26 g of Mg(NO.sub.3).sub.2.6H.sub.2O, 17.85 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 216.45 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 500 ml of distilled water, and NaOH solution (3M) was added dropwise under quick stirring to obtain a pH value of 9.3 at the end of the precipitation. The resulting precipitate was heated at 65 C. for 90 minutes under stirring for it to be aged, stood at room temperature for 12 hours, and then filtered. The resulting filter cake was washed with distilled water. After being dried at 120 C. for 24 hours, the filter cake was placed into a muffle furnace with a furnace temperature of 650 C. and calcined for 6 hours.

(72) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase; temperature programmed desorption test of ammonia showed that there were not enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 26 m.sup.2/g. In Table 1, Comparative Example 1 or Comparative Example 2 does not have the values of a, b, c, e and f. Rather, the values in the Comparative Example 1 or Comparative Example 2 correspond to a, b, c, 2 and 4.

(73) Catalyst evaluation: The evaluation conditions of the catalyst were the same as those in Example 1. The yield per pass of butadiene was 74.9%, the conversion per pass of butene was 79.9%, and the selectivity of butadiene was 93.7%.

(74) Stability of the catalyst: The stability of the catalyst was studied under the same evaluation conditions as in Example 1. The results are shown in Table 4.

(75) TABLE-US-00004 TABLE 4 Reaction Conversion of Selectivity to time (h) butene (%) butadiene (wt. %) 100 79.7 92.2 1,000 76.6 91.4 1,800 70.3 90.9

Comparative Example 2

(76) Catalyst preparation: 4.83 g of Cu(NO.sub.3).sub.2.3H.sub.2O, 5.23 g of Ba(NO.sub.3).sub.2, 17.85 g of Zn(NO.sub.3).sub.2.6H.sub.2O and 177.53 g of Fe(NO.sub.3).sub.3.9H.sub.2O were dissolved in 400 ml of distilled water, and NaOH solution (3M) was added dropwise under quick stirring to obtain a pH value of 9.3 at the end of the precipitation. The resulting precipitate was heated for 90 minutes at 65 C. under stirring for it to be aged, stood at room temperature for 12 hours, and then filtered. The resulting filter cake was washed with distilled water, and the remaining steps were the same as those in Example 1.

(77) The composition and acid sites of the catalyst are shown in Table 1 and Table 2. XRD characterization results indicated that the catalyst contained a spinel crystal phase and an -Fe.sub.2O.sub.3 crystal phase. The temperature programmed desorption test of ammonia showed that there were no enhanced acid sites on the catalyst surface, and the specific surface area of the catalyst was 20 m.sup.2/g.

(78) Catalyst evaluation: The evaluation conditions of the catalyst are the same as those in Example 1. The yield per pass of butadiene was 72.5%, the conversion per pass of butene was 78.4%, and the selectivity of butadiene was 92.5%.

(79) Stability of the catalyst: The stability of the catalyst was studied under the same evaluation conditions as in Example 1, and the results are shown in Table 5.

(80) TABLE-US-00005 TABLE 5 Reaction Conversion of Selectivity to time (h) butene (%) butadiene (wt. %) 100 78.4 92.5 1,000 76.7 91.3 1,800 71.2 90.4

(81) it can be seen from the evaluation results of the catalyst in Comparative Examples 1 and 2 and data in Table 4 and Table 5, when the catalysts of the Comparative Examples were used to catalyze the oxidative dehydrogenation reaction of butene to butadiene, the comparative catalysts presented lower catalytic activity and lower selectivity to the desired product than the catalysts provided in the present disclosure. Most importantly, the catalytic activity and selectivity of the catalysts in Comparative Examples 1 and 2 dropped sharply after 1,800 hours of reaction, but the catalytic activity and selectivity of the catalyst of the present disclosure remained at a high level after 6,000 hours of reaction time, which shows that the catalysts of the present disclosure possess high stability.