Catalyst for producing acrylonitrile

Abstract

The present invention relates to a catalyst composition comprising a complex of catalytic oxides containing molybdenum, bismuth, cerium, iron, chromium, at least one element of group A, at least one element of group B, and optionally at least one element of group C, wherein the relative ratios of these elements are represented by the formula (1): Mo 12 Bi a Ce b Fe c Cr d A e B f C g O x and relates to a catalyst composition. The present invention also relates to a method for ammoxidation of olefins, which comprises reacting an olefin with a molecular oxygen-containing gas and ammonia in the gas phase at high temperature and high pressure in the presence of the catalyst composition.

Description

Technical Field

[0001] The present invention relates to an improved catalyst composition useful for ammoxidizing unsaturated hydrocarbons to their corresponding unsaturated nitriles. In certain embodiments, the present invention is directed to improved processes and catalysts for ammoxidizing propylene to acrylonitrile and / or isobutylene to methacrylonitrile. More specifically, the present invention relates to an improved ammoxidation catalyst comprising a complex of a catalytic oxide comprising molybdenum, bismuth, cerium, iron, chromium, at least one Group A element, at least one Group B element, and optionally at least one Group C element, wherein the Group A consists of sodium, potassium, rubidium, and cesium; the Group B consists of nickel, cobalt, manganese, zinc, magnesium, calcium, strontium, cadmium, and barium; and the Group C consists of silver, gold, ruthenium, rhodium, palladium, osmium, iridium, platinum, and mercury. The present invention further relates to improved processes and catalysts for ammoxidizing propylene to acrylonitrile and / or isobutylene to methacrylonitrile using a selectivity catalyst useful for producing unsaturated nitriles in high yields. For example, the catalysts of the present invention exhibit a combination of high overall conversion of propylene and high selectivity to acrylonitrile compared to similar catalysts.

Background Art

[0002] Catalysts containing oxides of iron, bismuth, and molybdenum, promoted with suitable elements, for use in the conversion (i.e., ammoxidation) of propylene at elevated temperatures in the presence of ammonia, and molecular oxygen sources (e.g., air) for producing acrylonitrile are known. There is a continuing need to improve catalysts useful for converting olefins to their corresponding unsaturated nitriles (e.g., ammoxidation of propylene to produce acrylonitrile). The object of the present invention is a catalyst composition containing a complex of catalytic oxides containing a unique combination of relative ratios of elements, which imparts good performance to the catalytic ammoxidation of unsaturated hydrocarbons to their corresponding unsaturated nitriles. For example, propylene, isobutylene or a mixture thereof becomes acrylonitrile, methacrylonitrile and a mixture thereof, respectively. Another object of the present invention is a method for the ammoxidation of olefins, which comprises reacting an olefin with a molecular oxygen-containing gas and ammonia in the gas phase at high temperature and high pressure in the presence of a catalyst containing a complex of catalytic oxides. The present invention also relates to a method for converting an olefin selected from the group consisting of propylene, isobutylene or a mixture thereof into acrylonitrile, methacrylonitrile and a mixture thereof, respectively, by reacting the olefin with a molecular oxygen-containing gas and ammonia in the gas phase at high temperature and high pressure in the presence of a catalyst containing the complex of catalytic oxides described herein.

Summary of the Invention

[0003] The present invention is directed to an improved catalyst and method for ammoxidizing unsaturated hydrocarbons to their corresponding unsaturated nitriles. For example, propylene and / or isobutylene becomes acrylonitrile and / or methacrylonitrile, respectively. In one embodiment, the catalyst composition comprises a complex of catalytic oxides containing molybdenum, bismuth, cerium, iron, chromium, at least one Group A element, at least one Group B element, and optionally at least one Group C element, where Group A consists of sodium, potassium, rubidium, and cesium; Group B consists of nickel, cobalt, manganese, zinc, magnesium, calcium, strontium, cadmium, and barium; Group C consists of silver, gold, ruthenium, rhodium, palladium, osmium, iridium, platinum, and mercury; and the relative ratios of these elements are represented by formula (1): Mo 12 Bi a Ce b Fe c Cr d Ae B f C g O x is represented by (1). (In the formula,[[]] a is from about 0.05 to about 4; b is from about 0.01 to about 3; c is from about 0.01 to about 4; d is from about 0.01 to about 2; e is from about 0.01 to about 2; f is from about 0.01 to about 10; g is from about 0 to about 0.2; x is a number determined by the valence requirements of other existing elements; (c / d is from about 7 to about 12))

[0004] In another embodiment, the catalyst composition comprises a complex of a catalytic oxide containing molybdenum, bismuth, cerium, iron, chromium, at least one Group A element, at least one Group B element, and optionally at least one Group C element, where Group A consists of sodium, potassium, rubidium, and cesium; Group B consists of nickel, cobalt, manganese, zinc, magnesium, calcium, strontium, cadmium, and barium; Group C consists of silver, gold, ruthenium, rhodium, palladium, osmium, iridium, and platinum, and the relative ratios of these elements are represented by formula (1): Mo 12 Bi a Ce b Fe c Cr d A e B f C g O x is represented by (1). (In the formula,[[]] a is from about 0.05 to about 4; b is from about 0.3 to about 3; c is from about 0.01 to about 4; d is from about 0.01 to about 2; e is from about 0.01 to about 2; f is from about 0.01 to about 10; g is from about 0 to about 0.2; x is a number determined by the valence requirements of the other elements present; c / d is from about 2 to about 17)

[0005] In some embodiments, the catalyst composition exhibits a ratio of scheelite (m-phase + t-phase):β-MMoO of about 0.3 or less, and the amounts of the m-phase, t-phase, and β-MMoO phases are determined using X-ray diffraction and a modified Rietveld analysis model. 4 phase, and the amounts of the m-phase, t-phase, and β-MMoO 4 phase are determined using X-ray diffraction and a modified Rietveld analysis model.

[0006] For example, in one embodiment, the catalyst composition comprises a complex of a catalytic oxide comprising molybdenum, bismuth, cerium, iron, chromium, at least one Group A element, at least one Group B element, and optionally at least one Group C element, where Group A consists of sodium, potassium, rubidium, and cesium; Group B consists of nickel, cobalt, manganese, zinc, magnesium, calcium, strontium, cadmium, and barium; Group C consists of silver, gold, ruthenium, rhodium, palladium, osmium, iridium, and platinum, and the relative ratios of these elements are represented by formula (1), and the catalyst composition exhibits a ratio of scheelite (m-phase + t-phase):β-MMoO of about 0.3 or less, 4 and the amounts of the m-phase, t-phase, and β-MMoO 4 phase are determined using X-ray diffraction and a modified Rietveld analysis model. Mo 12 Bi a Ce b Fe c Cr d A e B f C g O x (1) (wherein a is from about 0.05 to about 4; b is from about 0.01 to about 3; c is from about 0.01 to about 4; d is from about 0.01 to about 2; e is from about 0.01 to about 2; f is from about 0.01 to about 10; g is from about 0 to about 0.2; x is a number determined by the valence requirements of the other elements present; c / d is from about 2 to 36)

[0007] Another embodiment is directed to a process for the ammoxidation of olefins. This process comprises reacting, in the gas phase, at elevated temperature and pressure, an olefin with a molecular oxygen-containing gas and ammonia in the presence of a catalyst comprising a complex of catalytic oxides of molybdenum, bismuth, cerium, iron, chromium, at least one Group A element, at least one Group B element, and optionally at least one Group C element. Other objects and features will be in part apparent and in part pointed out hereinafter.

DETAILED DESCRIPTION OF THE INVENTION

[0008] The present invention is directed to a catalyst composition comprising a complex of catalytic oxides that includes a unique combination of relative ratios of elements and imparts good performance in the catalytic ammoxidation of unsaturated hydrocarbons to their corresponding unsaturated nitriles. For example, propylene, isobutylene, or mixtures thereof are converted to acrylonitrile, methacrylonitrile, and mixtures thereof, respectively. The catalyst composition described herein (i.e., excluding any optional carrier) is a complex of catalytic oxides of molybdenum, bismuth, cerium, iron, chromium, at least one Group A element, at least one Group B element, and optionally at least one Group C element. Group A consists of sodium, potassium, rubidium, and cesium. Group B consists of nickel, cobalt, manganese, zinc, magnesium, calcium, strontium, cadmium, and barium. Group C consists of silver, gold, ruthenium, rhodium, palladium, osmium, iridium, platinum, and mercury. In certain embodiments, iron is in excess relative to chromium, and this excess is controlled within certain ranges described herein.

[0009] In one embodiment, the relative ratios of these elements in the catalyst composition are represented by formula (1): Mo 12 Bi a Ce b Fe c Cr d A e B f C g O x (1). (Wherein, a is from about 0.05 to about 4; b is from about 0.01 to about 3; c is from about 0.01 to about 4; d is from about 0.01 to about 2; e is from about 0.01 to about 2; f is from about 0.01 to about 10; g is from about 0 to about 0.2; x is a number determined by the valence requirements of the other elements present; (c / d is from about 2 to about 36))

[0010] In certain embodiments, c / d is about 2 to about 32, about 2 to about 28, about 2 to about 24, about 2 to about 20, about 4 to about 36, about 4 to about 32, about 4 to about 28, about 4 to about 24, about 4 to about 20, about 7 to about 36, about 7 to about 32, about 7 to about 28, about 7 to about 24, about 7 to about 20, about 7 to about 12, about 7 to about 11.5, about 7 to about 11, about 7 to about 10.5, about 7.5 to about 10.5, about 8 to about 10.5, or about 8 to about 10. In another embodiment, the catalyst composition has a high cerium content, and the relative ratios of these elements in the catalyst composition are represented by formula (1). Mo 12 Bi a Ce b Fe c Cr d A e B f C g O x (1) (Wherein, a is from about 0.05 to about 4; b is from about 0.3 to about 3; c is from about 0.01 to about 4; d is from about 0.01 to about 2; e is from about 0.01 to about 2; f is from about 0.01 to about 10; g is from about 0 to about 0.2; x is a number determined by the valence requirements of the other elements present; c / d is from about 2 to about 17)

[0011] In certain embodiments, c / d is from about 2 to about 16, from about 2 to about 14, from about 2 to about 12, from about 2 to about 10, from about 2 to about 8, or from about 2 to about 6. In these and other embodiments, a (bismuth) is from about 0.05 to about 3.5, from about 0.05 to about 3, from about 0.05 to about 2.5, from about 0.05 to about 2, from about 0.05 to about 1.5, from about 0.05 to about 1, from about 0.1 to about 1, from about 0.15 to about 1, from about 0.2 to about 1, from about 0.25 to about 1, from about 0.3 to about 1, from about 0.35 to about 1, from about 0.4 to about 1, from about 0.05 to about 1.25, from about 0.05 to about 0.75, from about 0.05 to about 0.5, from about 0.05 to about 0.4, from about 0.05 to about 0.3, from about 0.05 to about 0.2, or from about 0.05 to about 0.1.

[0012] In these and other embodiments, b (cerium) is from about 0.01 to about 2.5, from about 0.01 to about 2, from about 0.01 to about 1.5, from about 0.02 to about 1.5, from about 0.04 to about 1.5, from about 0.06 to about 1.5, from about 0.08 to about 1.5, from about 0.1 to about 1.5, from about 0.2 to about 1.5, from about 0.3 to about 1.5, from about 0.4 to about 1.5, or from about 0.5 to about 1.5. In certain high cerium content embodiments, b is from about 0.1 to about 3, from about 0.2 to about 3, from about 0.3 to about 3, from about 0.4 to about 3, from about 0.5 to about 3, from about 0.75 to about 3, from about 1 to about 3, from about 1.5 to about 3, from about 2 to about 3, from about 2.5 to about 3, from about 0.75 to about 2.5, or from about 1 to about 2.5. In these embodiments and other embodiments, c (iron) is from about 0.05 to about 4, from about 0.1 to about 4, from about 0.15 to about 4, from about 0.5 to about 4, from about 0.25 to about 4, from about 0.3 to about 4, from about 0.35 to about 4, from about 0.4 to about 4, from about 0.45 to about 4, from about 0.5 to about 4, from about 0.75 to about 4, from about 1 to about 4, from about 1 to about 3.5, from about 1 to about 3, from about 0.01 to about 3.5, from about 0.01 to about 3, from about 0.01 to about 21, from about 0.01 to about 1, from about 0.01 to about 0.5, from about 0.01 to about 0.4, from about 0.01 to about 0.3, from about 0.01 to about 0.2, from about 0.01 to about 0.1, or from about 0.01 to about 0.05.

[0013] In these embodiments and other embodiments, d (chromium) is from about 0.01 to about 1.5, from about 0.01 to about 1, from about 0.02 to about 1, from about 0.04 to about 1, from about 0.06 to about 1, from about 0.08 to about 1, from about 0.1 to about 1, from about 0.15 to about 1, from about 0.15 to about 0.5, from about 0.02 to about 2, from about 0.05 to about 2, from about 0.1 to about 2, from about 0.5 to about 2, from about 1 to about 2, or from about 1.5 to about 2. In these embodiments and other embodiments, e (Group A) is from about 0.01 to about 1.5, from about 0.01 to about 1, from about 0.01 to about 0.5, from about 0.01 to about 0.4, from about 0.01 to about 0.3, from about 0.01 to about 0.3, from about 0.02 to about 0.3, from about 0.04 to about 0.3, from about 0.06 to about 0.3, from about 0.08 to about 0.3, from about 0.01 to about 0.3, from about 0.02 to about 2, from about 0.05 to about 2, from about 0.1 to about 2, from about 0.5 to about 2, from about 1 to about 2, or from about 1.5 to about 2.

[0014] In these embodiments and other embodiments, f(group B) is from about 0.02 to about 10, from about 0.04 to about 10, from about 0.06 to about 10, from about 0.08 to about 10, from about 0.1 to about 10, from about 0.2 to about 10, from about 0.4 to about 10, from about 0.6 to about 10, from about 0.8 to about 10, from about 1 to about 10, from about 1.5 to about 10, from about 2 to about 10, from about 2.5 to about 10, from about 3 to about 10, from about 3.5 to about 10, from about 4 to about 10, from about 4.5 to about 10, from about 5 to about 10, from about 0.01 to about 8, from about 0.01 to about 7, from about 0.01 to about 6, from about 0.01 to about 5, from about 0.01 to about 4, from about 0.01 to about 3, from about 0.01 to about 2, from about 0.01 to about 1, from about 0.01 to about 0.5, from about 0.01 to about 0.25, from about 0.01 to about 0.2, from about 0.01 to about 0.1, or from about 0.01 to about 0.05.

[0015] In some embodiments, when present, g(group C) is from about 0.01 to about 0.2, from about 0.02 to about 0.2, from about 0.04 to about 0.2, from about 0.06 to about 0.2, from about 0.08 to about 0.2, or from about 0.1 to about 0.2. In alternative embodiments, g is from about 0 to about 0.15, from about 0 to about 0.1, from about 0 to about 0.05, from about 0 to about 0.04, from about 0 to about 0.03, from about 0 to about 0.02, or from about 0 to about 0.01.

[0016] In certain embodiments, A is selected from the group consisting of potassium, rubidium, and cesium. In other embodiments, A is selected from the group consisting of sodium, rubidium, and cesium. In further embodiments, A is selected from the group consisting of sodium, potassium, and cesium. In still further embodiments, A is selected from the group consisting of sodium, potassium, and rubidium. In another embodiment, A is selected from the group consisting of potassium, rubidium, and cesium. In a particular embodiment, A is selected from the group consisting of rubidium and cesium.

[0017] In certain embodiments, B is selected from the group consisting of nickel, manganese, zinc, magnesium, calcium, strontium, cadmium, and barium. In another embodiment, B is selected from the group consisting of nickel, cobalt, zinc, magnesium, calcium, strontium, cadmium, and barium. In a further embodiment, B is selected from the group consisting of nickel, cobalt, manganese, magnesium, calcium, strontium, cadmium, and barium. In one embodiment, B is selected from the group consisting of nickel, cobalt, manganese, zinc, calcium, strontium, cadmium, and barium. In another embodiment, B is selected from the group consisting of nickel, cobalt, manganese, zinc, magnesium, calcium, cadmium, and barium. In a further embodiment, B is selected from the group consisting of nickel, cobalt, manganese, zinc, magnesium, calcium, strontium, and barium. In yet another embodiment, B is selected from the group consisting of nickel, cobalt, manganese, zinc, magnesium, calcium, strontium, and cadmium.

[0018] In certain embodiments, when present, C is selected from the group consisting of gold, ruthenium, rhodium, palladium, osmium, iridium, platinum, and mercury. In another embodiment, C is selected from the group consisting of silver, ruthenium, rhodium, palladium, osmium, iridium, platinum, and mercury. In a further embodiment, C is selected from the group consisting of silver, gold, rhodium, palladium, osmium, iridium, platinum, and mercury. In one embodiment, C is selected from the group consisting of silver, gold, ruthenium, palladium, osmium, iridium, platinum, and mercury. In various embodiments, C is selected from the group consisting of silver, gold, ruthenium, rhodium, osmium, iridium, platinum, and mercury. In certain embodiments, C is selected from the group consisting of silver, gold, ruthenium, rhodium, palladium, iridium, platinum, and mercury. In another embodiment, C is selected from the group consisting of silver, gold, ruthenium, rhodium, palladium, osmium, platinum, and mercury. In a further embodiment, C is selected from the group consisting of silver, gold, ruthenium, rhodium, palladium, osmium, iridium, and mercury. In another embodiment, C is selected from the group consisting of silver, gold, ruthenium, rhodium, palladium, osmium, iridium, and platinum.

[0019] According to some embodiments, one or more specific elements may be excluded from the catalyst composition (i.e., components containing that element are not added during the preparation of the catalyst oxide component of the catalyst composition). For example, in one embodiment, the catalyst composition does not contain potassium. In another embodiment, the catalyst composition does not contain rubidium. In a further embodiment, the catalyst composition does not contain sodium. In another embodiment, the catalyst composition does not contain magnesium. In still a further embodiment, the catalyst composition does not contain calcium. Other elements or promoters may be included in the catalyst composition. For example, in some embodiments, the catalyst composition contains one or more elements selected from the group consisting of phosphorus, tin, indium, antimony, tellurium, lithium, thallium, boron, germanium, and rare earth elements (defined herein as any one of La, Pr, Nd, Pm, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, or Yb). For example, in one embodiment, the catalyst composition contains a small amount of phosphorus that has a beneficial effect on the abrasion resistance of the catalyst.

[0020] Bismuth, cerium, iron, and chromium can be introduced into the catalyst composition in any compound form containing these elements, for example, as oxides or as salts that produce oxides upon calcination. In certain embodiments, water-soluble salts that are easily dispersed in the catalyst but form stable oxides upon heat treatment may be used. For example, in one embodiment, the sources for introducing these elements include bismuth nitrate, cerium nitrate, ferric nitrate, and chromium nitrate. The molybdenum component of the catalyst composition can be introduced from any molybdenum oxide. However, hydrolyzable or decomposable molybdenum salts are preferably utilized as the molybdenum source (e.g., ammonium heptamolybdate). Any other necessary or optional components (i.e., the elements of Group A, Group B, and Group C) and any element or promoter of the catalyst composition (e.g., P, Sn, Te, B, Ge, In, or mixtures thereof) may be derived from any suitable source. For example, cobalt, nickel, and magnesium can be introduced into the catalyst using nitrates. Further, magnesium can be introduced into the catalyst as an insoluble carbonate or hydroxide that becomes an oxide upon heat treatment. Phosphorus can be introduced into the catalyst as an alkali metal salt, alkaline earth metal salt, ammonium salt, or as phosphoric acid.

[0021] The necessary and / or optional alkali components of the catalyst composition (e.g., Rb, Li, Na, K, Cs, or mixtures thereof) can be introduced into the catalyst as oxides or as salts that yield oxides upon calcination. In certain embodiments, salts such as nitrates that are readily available and readily soluble are used to incorporate the elements into the catalyst. To convert propylene, ammonia, and oxygen to acrylonitrile, it has been confirmed that including certain elements is detrimental to obtaining a catalyst that improves the yield of acrylonitrile. For example, including vanadium results in a catalyst composition that reacts more aggressively with the propylene feedstock and has low selectivity for the desired product, producing more carbon oxides (CO χ ) and less acrylonitrile production. Thus, in one embodiment, the catalyst composition is substantially free of vanadium. As used herein, "substantially free" with respect to vanadium means that the atomic ratio to molybdenum is less than 0.2:12. The catalyst compositions described herein can be analyzed using X-ray diffraction techniques such as those described in Example 3 below. In certain embodiments, the catalyst compositions described herein exhibit a particular X-ray diffraction (XRD) pattern that includes peaks at 2θ angles of about 23 ± 0.3 degrees, about 28 ± 0.3 degrees, and / or about 26.5 ± 0.3 degrees.

[0022] In one embodiment, the catalyst composition exhibits X-ray diffraction peaks at 2θ angles of about 28 ± 0.3 degrees and about 26.5 ± 0.3 degrees, and the intensity ratio of the strongest X-ray diffraction peak within the 2θ angle of about 28 ± 0.3 degrees to the strongest X-ray diffraction peak within the 2θ angle of about 26.5 ± 0.3 degrees is about 0.50 or less, about 0.40 or less, about 0.30 or less, about 0.20 or less, about 0.18 or less, about 0.16 or less, about 0.14 or less, about 0.12 or less, or about 0.1 or less. For example, it is about 0.05 to about 0.5, about 0.05 to about 0.4, about 0.1 to about 0.4, about 0.1 to about 0.3, or about 0.1 to about 0.2.

[0023] In certain embodiments, the catalyst composition exhibits X-ray diffraction peaks at 2θ angles of about 23 ± 0.3 degrees and about 26.5 ± 0.3 degrees, and the intensity ratio of the strongest X-ray diffraction peak within the 2θ angle of about 23 ± 0.3 degrees to the strongest X-ray diffraction peak within the 2θ angle of about 26.5 ± 0.3 degrees is about 0.1 or more, about 0.11 or more, about 0.12 or more, about 0.13 or more, about 0.14 or more, about 0.15 or more, about 0.16 or more, about 0.17 or more, about 0.18 or more, about 0.19 or more, about 0.20 or more, about 0.25 or more, about 0.3 or more, about 0.35 or more, about 0.4 or more, about 0.45 or more, or about 0.5 or more. For example, it is about 0.1 to about 0.5, about 0.11 to about 0.5, about 0.12 to about 0.5, about 0.13 to about 0.5, about 0.14 to about 0.5, about 0.15 to about 0.5, about 0.15 to about 0.4, about 0.15 to about 0.3, or about 0.15 to about 0.2.

[0024] In certain embodiments, the catalyst composition exhibits X-ray diffraction peaks at 2θ angles of about 23 ± 0.3 degrees and about 28 ± 0.3 degrees, and the intensity ratio of the strongest X-ray diffraction peak within the 2θ angle of about 23 ± 0.3 degrees to the strongest X-ray diffraction peak within the 2θ angle of about 28 ± 0.3 degrees is about 0.5 or greater, about 0.6 or greater, about 0.7 or greater, about 0.8 or greater, about 0.9 or greater, about 1 or greater, about 1.2 or greater, about 1.4 or greater, about 1.6 or greater, about 1.8 or greater, about 2 or greater, about 2.2 or greater, about 2.4 or greater, about 2.6 or greater, about 2.8 or greater, or about 3 or greater. For example, it is about 0.2 to about 3, about 0.2 to about 2, about 0.3 to about 3, or about 0.3 to about 2. In another embodiment, the catalyst composition exhibits X-ray diffraction peaks at 2θ angles of about 23 ± 0.3 degrees and about 28 ± 0.3 degrees, and the intensity ratio of the strongest X-ray diffraction peak within the 2θ angle of about 23 ± 0.3 degrees to the strongest X-ray diffraction peak within the 2θ angle of about 28 ± 0.3 degrees is about 0.5 to about 2, about 1 to about 2, about 1.2 to about 2, about 1.4 to about 2, or about 1.4 to about 1.8.

[0025] In certain other embodiments, the catalyst composition can be analyzed using X-ray diffraction (XRD) and modified Rietveld analysis. In this aspect, the crystal phase of the catalyst composition is analyzed using XRD analysis known in the art. Thereafter, the diffraction pattern of the catalyst composition is analyzed by the modified Rietveld analysis described herein. According to the modified Rietveld analysis, the complete diffraction pattern is simulated through first-principles calculations based on the atomic structure of the individual phases from the assumed phase composition of the measured sample. The correspondence between the simulated diffraction pattern and the measured diffraction pattern can then be made through the determination of covariance. The Rietveld analysis can be performed using the GSAS software described in Larson et al., "General Structural Analysis System (GSAS)", Los Alamos National Laboratory Report LAUR 86-784 (2004) and Toby, "EXPGUI, A Graphical User Interface for GSAS", J. Appl. Cryst., 34, 210-221 (2001), both of which are incorporated herein by reference. GSAS and EXPGUI are available at https: / / subversion.xor.aps.anl.gov / trac / EXPGUI / wiki.

[0026] The modified Rietveld model includes four phases that can be described as follows.

Table 1

[0027] As used herein, "m-phase" refers to a component that is monoclinic scheelite as determined by the modified Rietveld analysis described herein. As used herein, "t-phase" refers to a component that is tetragonal scheelite as determined by the modified Rietveld analysis described herein. The starting atomic coordinates are the same as those reported in the literature reference. The starting lattice constants are given here and are slightly different from the literature values. The thermal displacement parameter U iso is given in units of Å 2 . β-FeMoO 4 , the structure described in Sleight et al., Inorg. Chem. 7, 1093-8 (1968), which is incorporated herein by reference. Space group C2 / m, a = 10.194 Å, b = 9.229 Å, c = 7.012 Å, β = 107.08°. U isoIt is 0.01 for Fe, 0.005 for Mo, and 0.02 for O. The starting Fe occupancy is 1.000 for both.

[0028] Fe 2 (MoO 4 ) 3 , the structure described in Chen, Mater. Res. Bull., 14, 1583 - 90 (1979), which is incorporated herein by reference. Space group P2 1 / a, a = 15.820 Å, b = 9.347 Å, c = 18.196 Å, β = 125.60°. U iso is 0.01 for Fe and Mo, and 0.02 for O. Ce 2 (MoO 4 ) 3 , the structure described in Brixner et al., J. Solid State Chem., 5, 247 - 9 (1972), which is incorporated herein by reference. Space group C2 / c, a = 16.881 Å, b = 11.825 Å, c = 15.953 Å, β = 108.73°. U iso is 0.01 for Ce and Mo, and 0.02 for O. The starting Ce occupancy is 1.000 for all. NaBi(MoO 4 ) 2 , the structure described in Waskowska et al., Solid State Chem., 178, 2218 - 24 (2005), which is incorporated herein by reference.

[0029] Space group I4 1 / a, a = 5.322 Å, c = 11.851 Å. U iso is 0.01 for Mo, and 0.02 for Na, Bi, and O. The background is modeled using either a three - term cosine Fourier series or a three - term shifted Chebyshev polynomial.

[0030] The amorphous component of the catalyst is modeled using seven Debye scattering terms (diffuse scattering function 1 in GSAS) with thermal motion correction. Each term is modeled as a Si-O vector with a thermal displacement parameter (U) of 0.05 Å 2 The Si-O distances for the seven terms are fixed at 1.55 Å, 2.01 Å, 2.53 Å, 2.75 Å, 3.49 Å, 4.23 Å, and 4.97 Å, and their amplitudes are optimized by Rietveld fitting. Phases and parameters are gradually introduced into the model to ensure stable refinement. At each step, a least-squares refinement of 5 - 10 cycles is performed to stabilize the model before the next component is introduced. A correction factor of 5 (i.e., 50%) for all parameters except the scale factors of the phases is used to reduce overshoot and oscillation. The procedure is as follows:

[0031] 1. The starting model contains only the β-FeMoO 4 phase with its lattice constant fixed and its profile Y (Lorentz lattice strain) set to 75. Only the scale factor of the 3-term background function and the β-FeMoO 4 phase is variable. 2. Add the shift parameter (sample displacement). 3. The lattice constant of β-FeMoO 4 is made variable. 4. Add the other three phases, all with fixed lattice constants, profile X (Lorentz Scherrer broadening) set to 20, and their scale factors variable. 5. Add the seven diffuse scattering terms with their amplitudes variable. 6. The lattice constants of the two scheelite-like phases are made variable. 7. The profile Y of β-FeMoO 4 and profile X of the other three phases are made variable. 8. The Fe occupancy of the β-FeMoO 4 phase and the Ce 2 (MoO 4 ) 3 phase's Ce occupancy are made variable. 9. Continue the least squares refinement until convergence, i.e., the sum of (shift / esd) of all parameters 2 is less than 0.01.

[0032] β-MMoO 4 phase (M = Ni, Mg, Fe), Fe 2 (MoO 4 ) 3 Refine the XRD peaks related to the phase, m phase and t phase as described herein, and calculate the ratio of scheelite (m phase + t phase): β-MMoO 4 based on the refined values. In certain embodiments, the catalyst composition of the present invention exhibits a significantly reduced scheelite: β-MMoO 4 ratio. For example, the scheelite: β-MMoO 4 ratio calculated according to Rietveld refinement is about 0.3 or less, about 0.25 or less, about 0.2 or less, about 0.15 or less, about 0.1 or less, about 0.09 or less, about 0.08 or less, about 0.07 or less, about 0.06 or less, about 0.05 or less, about 0.04 or less, about 0.03 or less, about 0.02 or less, or about 0.01 or less. In combination with the compositional requirements including the atomic ratio of c(iron) to d(chromium) as disclosed above, a catalyst exhibiting a significantly reduced scheelite: β-MMoO4 ratio according to Rietveld refinement provides high conversion and desired selectivity in the ammoxidation of olefins such as propylene to produce acrylonitrile.

[0033] The catalyst composition described herein, which contains oxides of molybdenum, bismuth, cerium, iron, chromium, at least one element of Group A, at least one element of Group B, and optionally at least one element of Group C, may or may not be supported (i.e., the catalyst composition may further contain a support). Suitable supports can be selected, for example, from the group consisting of silica, alumina, zirconium, titania, or mixtures thereof. The support typically functions as a binder for the catalyst, resulting in a harder and more wear-resistant catalyst. Therefore, the supported catalyst is typically used when the ammoxidation reaction is carried out in a fluidized bed reactor. For commercial applications, an appropriate blend of both the above-described catalyst oxides and the support is selected to obtain acceptable activity and hardness (wear resistance) for the catalyst. The higher the proportion of the catalyst oxides, the higher the activity of the catalyst, but the hardness of the catalyst decreases. Typically, when used, the support occupies about 30% to about 70% by mass, about 35% to about 70% by mass, about 40% to about 70% by mass, about 40% to about 65% by mass, about 40% to about 60% by mass, about 40% to about 55% by mass, or about 45% to about 55% by mass of the catalyst composition. In certain embodiments, the support material may contain one or more promoter elements (e.g., silica sol containing sodium (Na)), and such promoter elements can be incorporated into the catalyst composition via the support material.

[0034] In one embodiment, the catalyst is supported using silica sol. When the average colloidal particle diameter of the silica sol is very small, the surface area of the produced catalyst increases, and the catalyst exhibits reduced selectivity. When the colloidal particle diameter is very large, the produced catalyst has low abrasion resistance. Therefore, in certain embodiments, the average colloidal particle diameter of the silica sol is about 8 nm to about 50 nm. The catalyst of the present invention can be prepared by any of a number of methods of catalyst preparation known to those skilled in the art. For example, the catalyst may be produced by co-precipitating various components. Subsequently, the co-precipitated mass may be dried and ground to an appropriate size. Alternatively, the co-precipitated material may be slurried and spray-dried according to the prior art. The catalyst may be extruded as pellets or formed into strands in oil as is well known in the art. For specific procedures for manufacturing the catalyst, reference is made to U.S. Patent No. 5,093,299; U.S. Patent No. 4,863,891 and U.S. Patent No. 4,766,232, which are hereby incorporated by reference herein. In one embodiment, the catalyst components may be mixed with a carrier in the form of a slurry and subsequently dried. In another embodiment, the catalyst components may be impregnated onto silica or other carriers.

[0035] The catalyst composition is prepared by mixing compounds of the elements essential for the desired catalyst oxide composition in appropriate molar amounts. Typically, for a silica-supported catalyst, an aqueous solution of ammonium heptamolybdate is mixed with a silica sol, and a slurry containing compounds of other elements (e.g., nitrates) is added thereto. Thereafter, the solids are dried, denitrified and calcined. The catalyst may be spray-dried at a temperature of about 110°C to about 350°C, about 110°C to about 250°C, or about 110°C to about 180°C. The denitrification temperature can range from about 100°C to about 500°C, or from about 250°C to about 450°C. Calcination may occur at a temperature of about 300°C to about 700°C, or from about 350°C to about 650°C. The composition of the resulting catalyst oxide can be determined by means known in the art, such as inductively coupled plasma (ICP) analysis.

[0036] The catalyst described in this specification is useful for an ammoxidation process for converting olefins into the corresponding unsaturated nitriles by reacting in the gas phase, at high temperature and high pressure, an olefin with a molecular oxygen-containing gas and ammonia in the presence of the catalyst. For example, in the gas phase, at high temperature and high pressure, an olefin selected from the group consisting of propylene, isobutylene or mixtures thereof is reacted with a molecular oxygen-containing gas and ammonia in the presence of the catalyst to convert it into acrylonitrile, methacrylonitrile and mixtures thereof, respectively. In certain embodiments, the ammoxidation reaction is carried out in a fluidized bed reactor. For example, the reactor design described in U.S. Patent No. 3,230,246, which is incorporated herein by reference, is suitable. In another embodiment, other known types of reactors, such as transport line reactors, may be used for the ammoxidation reaction.

[0037] The conditions for the ammoxidation reaction are described, for example, in U.S. Patent No. 5,093,299; U.S. Patent No. 4,863,891; U.S. Patent No. 4,767,878 and U.S. Patent No. 4,503,001, which are incorporated herein by reference. Typically, the ammoxidation process is carried out by contacting propylene or isobutylene with a fluidized bed catalyst at high temperature in the presence of ammonia and oxygen to produce acrylonitrile or methacrylonitrile.

[0038] Any suitable oxygen source may be used. However, for economic reasons, it may be desirable to utilize air as the oxygen source. In certain embodiments, the molar ratio of oxygen to olefin in the feed is from about 0.5:1 to about 4:1, or from about 1:1 to about 3:1. In certain embodiments, the olefin comprises propylene, the oxygen source comprises air, and the molar ratio of air to propylene is from about 5:1 to about 20:1, from about 5:1 to about 15:1, from about 6:1 to about 12:1, from about 7:1 to about 15:1, from about 8:1 to about 15:1, from about 8:1 to about 14:1, from about 8:1 to about 13:1, or from about 8:1 to about 12:1.

[0039] Generally, for economic reasons, the molar ratio of ammonia to olefin in the feed during the reaction is a ratio of about 2:1 or less. For example, in certain embodiments, the molar ratio of ammonia to olefin in the feed during the reaction can vary from 0.5:1 to 2:1. For example, in one embodiment, the molar ratio of ammonia to olefin in the feed during the reaction is from about 0.5:1 to about 2:1, from about 0.5:1 to about 1.5:1, from about 0.5:1 to about 1.4:1, from about 0.5:1 to about 1.3:1, from about 0.5:1 to about 1.2:1, from about 0.5:1 to about 1.1:1, from about 0.5:1 to about 1:1, or from about 0.75:1 to about 1:1. In certain embodiments, it has been found that the catalysts described herein give acrylonitrile in high yields at relatively low ammonia to propylene feedstock ratios. For example, in one embodiment, the olefin comprises propylene and the molar ratio of ammonia to propylene is from about 0.9:1 to about 1.3:1, from about 0.9:1 to about 1.2:1, from about 0.9:1 to about 1.1:1, from about 1:1 to about 1.1:1, or from about 1:1 to about 1.05:1. These “low ammonia conditions” help to reduce unreacted ammonia in the reactor effluent, and conditions known as “ammonia breakthrough” help to reduce subsequent process waste. Specifically, unreacted ammonia needs to be removed from the reactor effluent prior to the recovery of acrylonitrile. Unreacted ammonia is typically removed by contacting the reactor effluent with sulfuric acid to ammonium acrylate, and in either case, the process waste stream will be treated and / or disposed of. Further, since ammonia is a relatively expensive reagent, increased efficient utilization of ammonia further reduces production costs.

[0040] In one embodiment for the production of acrylonitrile from propylene, the ammonia to propylene ratio is from about 0.9:1 to about 1.3:1 and the air to propylene ratio is from about 8.0:1 to about 12.0:1. The reaction can be carried out at a temperature of about 260°C to about 600°C, about 310°C to about 500°C, or about 350°C to about 480°C. The contact time is not critical but is generally about 0.1 to about 50 seconds. In certain embodiments, the contact time is about 1 to about 15 seconds. The reaction product can be recovered and purified by any known method. One such method involves washing the exhaust gas from the reactor with cold water or a suitable solvent to remove the reaction product, and then purifying the reaction product by distillation.

[0041] Surprisingly, the catalyst of the present invention has been found to contribute to the improvement of olefin conversion. For example, by using the catalyst of the present invention in an olefin ammoxidation process where the olefin contains propylene, the olefin conversion is about 85% or more, about 86% or more, about 87% or more, about 88% or more, about 89% or more, about 90% or more, about 91% or more, about 92% or more, about 93% or more, about 94% or more, about 95% or more, about 96% or more, about 97% or more, about 98% or more, about 99% or more, about 99.1% or more, about 99.2% or more, about 99.3% or more, about 99.7% or more, about 99.8% or more, about 99.6% or more, about 99.7% or more, about 99.8% or more, or about 99.9% or more, and typically about 98% to about 99%.

[0042] Surprisingly, in some embodiments, the catalyst of the present invention has been found to contribute to the improvement of nitrile yield. For example, by using the catalyst of the present invention in an olefin ammoxidation process where the olefin contains propylene, the nitrile yield is about 70% or more, about 72% or more, about 74% or more, about 76% or more, about 78% or more, about 80% or more, about 82% or more, about 84% or more, about 86% or more, about 88% or more, or about 90% or more. This catalyst is described herein for the ammoxidation of propylene to acrylonitrile, but this catalyst can also be used for the oxidation of propylene to acrylic acid. Such a process is typically a two-step process in which propylene is converted mainly to acrolein in the first step in the presence of a catalyst and acrolein is converted mainly to acrylic acid in the second step in the presence of a catalyst. The catalyst described herein is suitable for use in the first step for the oxidation of propylene to acrolein.

Examples

[0043] To illustrate the present invention, the catalysts of the present invention, as well as similar catalysts without one or more essential elements and / or similar catalysts containing those elements in various proportions, were prepared and then evaluated under similar reaction conditions. These examples are given for illustrative purposes only.

[0044] (Example 1 - Catalyst Preparation) Sample 1. Formula 50% Ni 3.85 Mg 2.89 Fe 0.843 Rb 0.13 Cr 0.082 Bi 1.35 Ce 0.67 Mo 12 O 47.57 + 50 mass% SiO 2 The catalyst was prepared as follows. In the following order, Fe(NO 3 ) 3 ·9H 2 O (32.15 g), Ni(NO 3 ) 2 ·6H 2 O (105.83 g), Mg(NO 3 ) 2 ·6H 2 O (69.98 g), Bi(NO 3 ) 3 ·5H 2 O (61.77 g), Cr(NO 3 ) 3 ·9H 2 O (3.08 g), RbNO 3 (1.81 g), (NH4 ) 2 Ce(NO 3 ) 6 (69.81 g of 50% solution) was used to dissolve metal nitrates in water (30.51 g) at about 55 °C to form a mixed metal nitrate solution. Ammonium heptamolybdate (AHM) (200.07 g) was dissolved in 220.08 g of distilled water at about 65 °C. Then, silica (746.27 of 33.5% SiO 2 sol) was added, followed by the mixed metal nitrate solution. Then, the resulting slurry was spray-dried. The obtained substance was denitrified at 290 °C for 3 hours and then at 425 °C for 3 hours, and then calcined in air at 580 °C for 3 hours. Sample 2. Formula 50% Ni 3.43 Mg 2.57 Fe 1.50 Rb 0.13 Cr 0.36 Bi 0.60 Ce 1.20 Mo 12 O 48.16 + 50 mass% SiO 2 The catalyst of was prepared as follows. In the following order, Fe(NO 3 )3·9H 2 O (58.43 g), Ni(NO 3 ) 2 ·6H 2 O (96.15 g), Mg(NO 3 ) 2 ·6H 2 O (63.56 g), Bi(NO 3 ) 3 ·5H 2 O (28.05 g), Cr(NO 3 ) 3 ·9H 2 O (13.99 g), RbNO 3 (1.85 g), (NH 4 ) 2 Ce(NO 3 ) 6(126.91 g of 50% solution) The metal nitrate was dissolved in water (29.11 g) at about 55 °C to form a mixed metal nitrate solution. Ammonium heptamolybdate (AHM) (204.29 g) was dissolved in 224.72 g of distilled water at about 65 °C. Then, silica (746.27 of 33.5% SiO2 sol) was added, followed by the addition of the mixed metal nitrate solution. Subsequently, the resulting slurry was spray-dried. The obtained substance was denitrified at 290 °C for 3 hours and then at 425 °C for 3 hours, and then calcined in air at 580 °C for 3 hours.

[0045] Sample 3. Formula 50% Ni 3.89 Mg 2.92 Fe 1.75 Rb 0.19 Cr 0.05 Bi 0.19 Ce 1.22 Mo 12 O 48.32 + 50 mass% SiO 2 The catalyst of was prepared as follows. In the following order, Fe(NO 3 ) 3 ·9H 2 O (69.29 g), Ni(NO 3 ) 2 ·6H 2 O (110.82 g), Mg(NO 3 ) 2 ·6H 2 O (73.29 g), Bi(NO 3 ) 3 ·5H 2 O (9.24 g), Cr(NO 3 ) 3 ·9H 2 O (1.91 g), RbNO 3 (2.7 g), (NH 4 ) 2 Ce(NO 3 ) 6(132.88 g of 50% solution) The metal nitrate was dissolved in water (29.69 g) at about 55 °C to form a mixed metal nitrate solution. Ammonium heptamolybdate (AHM) (207.69 g) was dissolved in 228.45 g of distilled water at about 65 °C. Then, silica (746.27 of 33.5% SiO2 sol) was added, followed by the addition of the mixed metal nitrate solution. Subsequently, the resulting slurry was spray-dried. The obtained substance was denitrified at 290 °C for 3 hours and then at 425 °C for 3 hours, and then calcined in air at 580 °C for 3 hours.

[0046] Sample 4. Formula 50% Ni 3.89 Mg 2.92 Fe 0.36 Rb 0.19 Cr 0.05 Bi 0.36 Ce 2.43 Mo 12 O 48.92 + 50 mass% SiO 2 The catalyst of was prepared as follows. In the following order, Fe(NO 3 ) 3 ·9H 2 O (13.69 g), Ni(NO 3 ) 2 ·6H 2 O (105.13 g), Mg(NO 3 ) 2 ·6H 2 O (69.52 g), Bi(NO 3 ) 3 ·5H 2 O (16.44 g), Cr(NO 3 ) 3 ·9H 2 O (1.81 g), RbNO 3 (2.56 g), (NH 4 ) 2 Ce(NO 3 ) 6(252.09 g of a 50% solution) of metal nitrates was dissolved in water (23.24 g) at about 55 °C to form a mixed metal nitrate solution. Ammonium heptamolybdate (AHM) (197.01 g) was dissolved in 216.72 g of distilled water at about 65 °C. Then, silica (746.27 of 33.5% SiO2 sol) was added, followed by the addition of the mixed metal nitrate solution. Subsequently, the resulting slurry was spray-dried. The obtained substance was denitrified at 290 °C for 3 hours and then at 425 °C for 3 hours, and then calcined in air at 580 °C for 3 hours.

[0047] (Comparative catalyst) Comparative Example A. Formula 50 mass% Ni 1.81 Mg 1.36 Fe 2.64 Rb 0.13 Cr 0.13 Bi 1.05 Ce 2.11 Mo 12 O 49.18 + 50 mass% SiO 2 The catalyst of was prepared as follows. In the following order, Fe(NO 3 ) 3 ·9H 2 O (96.57 g), Ni(NO 3 ) 2 ·6H 2 O (47.67 g), Mg(NO 3 ) 2 ·6H 2 O (31.53 g), Bi(NO 3 ) 3 ·5H 2 O (46.36 g), Cr(NO 3 ) 3 ·9H 2 O (4.63 g), RbNO 3 (1.74 g), (NH 4 ) 2 Ce(NO 3 ) 6(209.69 g of 50% solution) The metal nitrate was dissolved in water (25.39 g) at about 55 °C to form a mixed metal nitrate solution. Ammonium heptamolybdate (AHM) (192.03 g) was dissolved in 211.23 g of distilled water at about 65 °C. Then, silica (746.27 of 33.5% SiO2 sol) was added, followed by the addition of the mixed metal nitrate solution. Subsequently, the resulting slurry was spray-dried. The obtained substance was denitrified at 290 °C for 3 hours and then at 425 °C for 3 hours, and then calcined in air at 580 °C for 3 hours.

[0048] Using the techniques and procedures described in Example 1 of U.S. Patent No. 7,071,140, several other comparative catalysts were prepared. For the catalysts of Comparative Examples B - E, one or more of chromium, cerium, or rubidium were excluded from the formulation. In Comparative Examples D and E, cesium (CsNO 3 ) and potassium (KNO 3 ) were used in place of rubidium, respectively. Comparative Example B. 50 mass% Ni 5.0 Mg 2.0 Fe 1.8 Bi 0.45 Ce 0.9 Rb 0.15 Mo 12 O 48.25 + 50 mass% SiO 2 . Comparative Example C. 50 mass% Ni 5.0 Mg 2.0 Fe 1.8 Bi 0.45 Cr 0.1 Rb 0.15 Mo 12 O 46.6 + 50 mass% SiO 2 . Comparative Example D. 50 mass% Ni 5.0 Mg 2.0 Fe 1.8 Bi 0.45 Ce 0.9 Cr 0.1 K 0.15 Mo 12 O 48.4 + 50 mass% SiO 2 . Comparative Example E. 50 mass% Ni 5.0 Mg2.0 Fe 1.8 Bi 0.45 Ce 0.9 Cr 0.1 Cs 0.15 Mo 12 O 48.4 + 50 mass% SiO 2 。 Comparative Example F. 50 mass% Ni 5.0 Mg 2.0 Fe 1.8 Bi 0.45 Ce 0.9 Cr 0.1 Rb 0.15 Mn 1.0 Mo 12 O 49.4 + 50 mass% SiO 2 。This catalyst added manganese, Mn(NO 3 ) 2 (32.699 g of 51.1% solution) to the catalyst formulation. Comparative Example G. 50 mass% Ni 5.0 Mg 2.0 Fe 1.8 Bi 0.45 Ce 0.9 Cr 0.1 Rb 0.15 Pd 0.1 Mo 12 O 48.5 + 50 mass% SiO 2 。This catalyst added the noble metal, palladium, Pd(NO 3 ) 2 (2.2 g) to the catalyst formulation. Comparative Example H. 50 mass% Ni 5.0 Mg 2.0 Fe 1.8 Bi 0.45 Ce 0.9 Cr 0.1 Rb 0.15 V 0.5 Mo 12 O 49.65 + 50 mass% SiO 2 。This catalyst added vanadium, NH 4 VO 3 (5.514 g) to the catalyst formulation.

[0049] Comparative Example I. 50 mass% Ni 5.0 Mg 2.0 Fe1.8 Bi 0.45 Ce 0.15 Cr 0.3 Rb 0.15 Mo 12 O 47.2 + 50 mass% SiO 2 。On an atomic basis, this catalyst was prepared such that the molar amount of cerium plus the molar amount of chromium was equal to the molar amount of bismuth. The method for preparing this catalyst is as follows: In a 1000 ml beaker, Fe(NO 3 ) 3 ·9H 2 O (72.939 g), Ni(NO 3 ) 2 ·6H 2 O (145.83 g), Mg(NO 3 ) 2 ·6H 2 O (51.434 g), Bi(NO 3 ) 3 ·5H 2 O (21.894 g), RbNO 3 (2.219 g), and (NH 4 ) 2 Ce(NO 3 ) 6 (16.496 g of a 50% solution) were dissolved in water at about 70 °C. Ammonium heptamolybdate (AHM) (212.504 g) was dissolved in 310 ml of distilled water. To this solution, CrO 3 (3.009 g) dissolved in 20 ml of water was added. Subsequently, silica (871.08 g of a 28.75% SiO 2 sol) was added, followed by the addition of the metal nitrates.

[0050] Comparative Example J. 50 mass% Ni 5.0 Mg 2.0 Fe 1.8 Bi 0.45 Ce 0.1 Cr 0.1 Rb 0.15 Mo 12 O 46.8 + 50 mass% SiO 2。The catalyst was prepared such that, on an atomic basis, the amount of cerium plus the amount of chromium was less than the amount of bismuth. The method for preparing this catalyst is as follows: In a 1000 ml beaker, Fe(NO 3 ) 3 ·9H 2 O (73.642 g), Ni(NO 3 ) 2 ·6H 2 O (147.236 g), Mg(NO 3 ) 2 ·6H 2 O (51.93 g), Bi(NO 3 ) 3 ·5H 2 O (22.105 g), RbNO 3 (2.24 g), (NH 4 ) 2 Ce(NO 3 ) 6 (11.104 g of a 50% solution) were dissolved in water at approximately 70 °C. Ammonium heptamolybdate (AHM) (214.553 g) was dissolved in 310 ml of distilled water. To this solution, CrO 3 (1.013 g) dissolved in 20 ml of water was added. Then, silica (871.08 g of a 28.75% SiO 2 sol) was added, followed by the addition of the metal nitrates.

[0051] Comparative Example K. 50 mass% Ni 5.0 Mg 2.0 Fe 1.8 Bi 2.0 Ce 0.9 Cr 0.1 Rb 0.15 Mo 12 O 46.8 + 50 mass% SiO 2 。The catalyst was prepared such that, on an atomic basis, the amount of cerium plus the amount of chromium was less than the amount of bismuth. The method for preparing this catalyst is as follows: In a 1000 ml beaker, Fe(NO 3 ) 3 ·9H 2 O (61.264 g), Ni(NO 3 ) 2 ·6H 2 O (122.488 g), Mg(NO3 ) 2 ·6H 2 O (43.201 g), Bi(NO 3 ) 3 ·5H 2 O (81.732 g), RbNO 3 (1.863 g), (NH) 2 Ce(NO 3 ) 6 (83.136 g of 50% solution) was dissolved in water at about 70 °C. Ammonium heptamolybdate (AHM) (178.49 g) was dissolved in 310 ml of distilled water. CrO 3 (0.843 g) dissolved in 20 ml of water was added thereto. Thereafter, silica (871.08 g of 28.75% SiO 2 sol) was added, followed by the addition of metal nitrates. ICP analysis of the obtained substance was performed to confirm that the catalyst contained the composition described above.

[0052] (Example 2 - Catalyst Test) Catalyst samples 1 - 4 and the comparative catalyst were tested in a 40 cc fluidized bed reactor. Propylene was fed to the reactor at a rate of 0.06 WWH (i.e., weight of propylene / weight of catalyst / hour). The pressure inside the reactor was maintained at 10 psig. The reaction temperature was 430 °C. After a stabilization period of about 20 hours, samples of the reaction products were collected. The reactor effluent was collected in a bubble - type scrubber containing cold HCl solution. The off - gas rate was measured with a soap - film flowmeter and the off - gas composition was determined with the aid of a gas chromatograph equipped with a split - column - gas - analyzer at the end of the experiment. At the end of the recovery operation, the total scrubber liquid was diluted to approximately 200 gms with distilled water. The weighted amount of 2 - butanone was used as an internal standard in an aliquot of about 50 grams of the diluted solution. 2 μl of the sample was analyzed by GC equipped with a flame ionization detector and a Carbowax column. The amount of NH 3 was determined by titrating the free HCl excess with NaOH solution. The results are described below.

[0053]

Table 2

[0054] (Example 3 - X-ray Diffraction Analysis) The new catalyst sample was analyzed as received without being pulverized. The sample powder was added to a zero-background cell to form a flat and densely packed sample for XRD analysis. Typical conditions for a Panalytical Empyrean series 3 diffractometer were as follows: Sample rotation Cu Kα radiation (wavelength Kα1 1.5406 Å) X-ray generator 45 kV, 40 mA Incident beam optics: Divergence slit: Fixed slit 1 / 8° Anti-scatter slit: Fixed slit 1 / 2° Diffracted beam optics: Solar slit: Solar slit 0.02 rad Anti-scatter slit: AS slit 7.5 mm Scanning range 5° - 100° Step size 0.013° Total scanning time 4:00 (240 minutes)

[0055] Catalyst sample 2 and Comparative Example A were also evaluated for X-ray diffraction peaks and further refined using Rietveld refinement as detailed herein. The results are reported in Tables 2 and 3 below. "23°:28°" corresponds to the intensity ratio of the strongest X-ray diffraction peak within a 2θ angle of about 23 ± 0.3 degrees to the strongest X-ray diffraction peak within a 2θ angle of about 28 ± 0.3 degrees.

Table 3

[0056] Modified XRD Rietveld refinement was performed according to the above procedure. β-MMoO 4 phase (M = Ni, Mg, Fe) phase, Fe 2 (MoO 4 ) 3Precision was carried out on the peaks related to the a phase, m phase, and t phase, and the ratio of scheelite (m phase + t phase): β-MMoO 4 was calculated. The results are reported in Table 3 below.

[0057]

Table 4

[0058] From the elemental composition of the active phase, such as those given for catalyst sample 2 in Table 3 and Comparative Example A, a typical ratio of the m phase based on the amount of Ce in the active phase can be calculated as a ratio of the whole active phase. When the stoichiometric amount of Bi in the active phase is greater than the stoichiometric amount of Ce in the active phase, the typical ratio of the m phase may be calculated assuming that all Ce is within the m phase and the m phase is represented by the formula CeBi(MoO 4 ) 3 . When the stoichiometric amount of Ce in the active phase is greater than the stoichiometric amount of Bi in the active phase, the typical ratio of the m phase may be calculated using the formula Ce x Bi (2-x) (MoO 4 ) 3 , where x is (2n Ce / (n Bi +n Ce ))). Based on the known active phase composition, the known atomic weights of various components, and the appropriate m phase formula described above, the typical mass percentage of the m phase can be determined. As shown in Table 4, the ratio of the measured m phase to the calculated typical m phase as measured by Rietveld analysis is very small in the catalyst composition of the present invention (Sample 2) compared to Comparative Example A.

[0059]

Table 5

[0060] Typically, in some embodiments, the measured and calculated representative m-phase ratio, as determined by leat belt analysis, is about 0.1 or less, about 0.09 or less, about 0.08 or less, about 0.07 or less, about 0.06 or less, about 0.05 or less, about 0.04 or less, about 0.03 or less, or about 0.02 or less. In that it contains a complex of catalytic oxides of molybdenum, bismuth, cerium, iron, chromium, at least one Group A element, at least one Group B element, and optionally at least one Group C element in certain proportions, the catalyst composition of the present invention is unique. This combination of elements in the relative proportions described herein has not heretofore been utilized in a single ammoxidation catalyst formulation. As explained in Table 1, in the ammoxidation of propylene to acrylonitrile, the catalyst of the present invention exhibits better performance than catalysts containing a similar combination of elements. More specifically, the catalyst of the present invention has shown a combination of high overall conversion of propylene and high selectivity to acrylonitrile as compared to similar catalysts. When introducing elements of the present invention or its preferred embodiments, the articles "a", "an", "the", and "said" shall be taken to mean one or more than one element. The terms "comprising", "including", and "having" are to be construed as inclusive and mean that there may be additional elements other than the recited elements. In view of the foregoing, it will be seen that several objects of the present invention are achieved and other advantageous results are obtained.

[0061] The foregoing description and the above embodiments are typical for the practice of the present invention, but in light of this specification, it will be apparent to those skilled in the art that many alternatives, modifications, and variations are obvious. Accordingly, all matters contained in the above specification are to be construed as illustrative and not in a limiting sense, and all such alternatives, modifications, and variations are intended to be included within the spirit and broader scope of the appended claims and to fall therein.

Claims

1. A catalyst composition comprising a catalyst oxide complex containing molybdenum, bismuth, cerium, iron, chromium, at least one element from group A, at least one element from group B, and optionally at least one element from group C, Group A consists of sodium, potassium, rubidium, and cesium; Group B consists of nickel, cobalt, manganese, zinc, magnesium, calcium, strontium, cadmium, and barium; Group C consists of silver, gold, ruthenium, rhodium, palladium, osmium, iridium, platinum, and mercury; The relative ratios of these elements are given by equation (1): Mo 12 Bi a Ce b Fe c Cr d A e B f C g O x The catalyst composition represented by (1). (In the formula, a is approximately 0.05 to approximately 4; b is approximately 0.3 to approximately 3; c is approximately 0.01 to approximately 4; d is approximately 0.01 to approximately 2; e is approximately 0.01 to approximately 2; f is approximately 0.01 to approximately 10; g is approximately 0 to approximately 0.2; x is a number determined by the valence requirements of the other elements present; c / d is approximately 2 to 17.

2. The catalyst composition according to claim 1, wherein c / d is about 7 to about 12, about 7 to about 11.5, about 7 to about 11, about 7 to about 10.5, about 7.5 to about 10.5, about 8 to about 10.5, or about 8 to about 10.

3. The catalyst composition according to claim 1, wherein c / d is about 2 to 16, about 2 to about 14, about 2 to about 12, about 2 to about 10, about 2 to about 8, or about 2 to about 6.

4. About 0.1 or less, about 0.09 or less, about 0.08 or less, about 0.07 or less, about 0.06 or less, about 0.05 or less, about 0.04 or less, about 0.03 or less, about 0.02 or less, or about 0.01 or less scheelite (m phase + t phase): β-MMoO 4 The ratio is shown, and the m phase, t phase and β-MMoO 4 The catalyst composition according to claim 1, wherein the amount of phase is determined using X-ray diffraction and a modified Rietveld analysis model.

5. A catalyst composition comprising a catalyst oxide complex containing molybdenum, bismuth, cerium, iron, chromium, at least one element from group A, at least one element from group B, and optionally at least one element from group C, Group A consists of sodium, potassium, rubidium, and cesium; Group B consists of nickel, cobalt, manganese, zinc, magnesium, calcium, strontium, cadmium, and barium; Group C consists of silver, gold, ruthenium, rhodium, palladium, osmium, iridium, platinum, and mercury; The relative ratios of these elements are expressed by equation (1), Scheelite (m phase + t phase) of approximately 0.3 or less: β-MMoO 4 Show the ratio, m phase, t phase and β-MMoO 4 A catalyst composition in which the amount of phase is determined using X-ray diffraction and a modified Rietveld analysis model. Mo 12 Bi a Ce b Fe c Cr d A e B f C g O x (1) (In the formula, a is approximately 0.05 to approximately 4; b is approximately 0.01 to approximately 3; c is approximately 0.01 to approximately 4; d is approximately 0.01 to approximately 2; e is approximately 0.01 to approximately 2; f is approximately 0.01 to approximately 10; g is approximately 0 to approximately 0.2; x is a number determined by the valence requirements of the other elements present; c / d is approximately 2 to 36.

6. About 0.25 or less, about 0.2 or less, about 0.15 or less, about 0.1 or less, about 0.09 or less, about 0.08 or less, about 0.07 or less, about 0.06 or less, about 0.05 or less, about 0.04 or less, about 0.03 or less, about 0.02 or less, or about 0.01 or less scheelite (m phase + t phase): β-MMoO 4 The ratio is shown, and the m phase, t phase and β-MMoO 4 The catalyst composition according to claim 5, wherein the amount of phase is determined using X-ray diffraction and a modified Rietveld analysis model.

7. The catalyst composition according to claim 5, wherein c / d is approximately 2 to approximately 32, approximately 2 to approximately 28, approximately 2 to approximately 24, approximately 2 to approximately 20, approximately 4 to approximately 36, approximately 4 to approximately 32, approximately 4 to approximately 28, approximately 4 to approximately 24, approximately 4 to approximately 20, approximately 7 to approximately 36, approximately 7 to approximately 32, approximately 7 to approximately 28, approximately 7 to approximately 24, approximately 7 to approximately 20, approximately 7 to approximately 12, approximately 7 to approximately 11.5, approximately 7 to approximately 11, approximately 7 to approximately 10.5, approximately 7.5 to approximately 10.5, approximately 8 to approximately 10.5, or approximately 8 to approximately 10.

8. The catalyst composition according to claim 1, wherein a is approximately 0.05 to approximately 3.5, approximately 0.05 to approximately 3, approximately 0.05 to approximately 2.5, approximately 0.05 to approximately 2, approximately 0.05 to approximately 1.5, approximately 0.05 to approximately 1, approximately 0.1 to approximately 1, approximately 0.15 to approximately 1, approximately 0.2 to approximately 1, approximately 0.25 to approximately 1, approximately 0.3 to approximately 1, approximately 0.35 to approximately 1, approximately 0.4 to approximately 1, approximately 0.05 to approximately 1.25, approximately 0.05 to approximately 0.75, approximately 0.05 to approximately 0.5, approximately 0.05 to approximately 0.4, approximately 0.05 to approximately 0.3, approximately 0.05 to approximately 0.2, or approximately 0.05 to approximately 0.

1.

9. The catalyst composition according to claim 1, wherein b is about 0.3 to about 3, about 0.4 to about 3, about 0.5 to about 3, about 0.75 to about 3, about 1 to about 3, about 1.5 to about 3, about 2 to about 3, about 2.5 to about 3, about 0.75 to about 2.5, or about 1 to about 2.

5.

10. The catalyst composition according to claim 5, wherein b is approximately 0.01 to approximately 2.5, approximately 0.01 to approximately 2, approximately 0.01 to approximately 1.5, approximately 0.02 to approximately 1.5, approximately 0.04 to approximately 1.5, approximately 0.06 to approximately 1.5, approximately 0.08 to approximately 1.5, approximately 0.1 to approximately 1.5, approximately 0.2 to approximately 1.5, approximately 0.3 to approximately 1.5, approximately 0.4 to approximately 1.5, approximately 0.5 to approximately 1.5, approximately 0.1 to approximately 3, approximately 0.2 to approximately 3, approximately 0.3 to approximately 3, approximately 0.4 to approximately 3, approximately 0.5 to approximately 3, approximately 0.75 to approximately 3, approximately 1 to approximately 3, approximately 1.5 to approximately 3, approximately 2 to approximately 3, approximately 2.5 to approximately 3, approximately 0.75 to approximately 2.5, or approximately 1 to approximately 2.

5.

11. The catalyst composition according to claim 1, wherein c is approximately 0.05 to approximately 4, approximately 0.1 to approximately 4, approximately 0.15 to approximately 4, approximately 0.5 to approximately 4, approximately 0.25 to approximately 4, approximately 0.3 to approximately 4, approximately 0.35 to approximately 4, approximately 0.4 to approximately 4, approximately 0.45 to approximately 4, approximately 0.5 to approximately 4, approximately 0.75 to approximately 4, approximately 1 to approximately 4, approximately 1 to approximately 3.5, approximately 1 to approximately 3, approximately 0.01 to approximately 3.5, approximately 0.01 to approximately 3.5, approximately 0.01 to approximately 3, approximately 0.01 to approximately 2, approximately 0.01 to approximately 1, approximately 0.01 to approximately 0.5, approximately 0.01 to approximately 0.4, approximately 0.01 to approximately 0.3, approximately 0.01 to approximately 0.2, approximately 0.01 to approximately 0.1, or approximately 0.01 to approximately 0.

05.

12. The catalyst composition according to claim 1, wherein d is approximately 0.01 to approximately 1.5, approximately 0.01 to approximately 1, approximately 0.02 to approximately 1, approximately 0.04 to approximately 1, approximately 0.06 to approximately 1, approximately 0.08 to approximately 1, approximately 0.1 to approximately 1, approximately 0.15 to approximately 1, approximately 0.15 to approximately 0.5, approximately 0.02 to approximately 2, approximately 0.05 to approximately 2, approximately 0.1 to approximately 2, approximately 0.5 to approximately 2, approximately 1 to approximately 2, or approximately 1.5 to approximately 2.

13. The catalyst composition according to claim 1, wherein e is approximately 0.01 to approximately 1.5, approximately 0.01 to approximately 1, approximately 0.01 to approximately 0.5, approximately 0.01 to approximately 0.4, approximately 0.01 to approximately 0.3, approximately 0.01 to approximately 0.3, approximately 0.02 to approximately 0.3, approximately 0.04 to approximately 0.3, approximately 0.06 to approximately 0.3, approximately 0.08 to approximately 0.3, approximately 0.1 to approximately 0.5, or approximately 0.2 to approximately 0.

4.

14. f is approximately 0.02 to 10, approximately 0.04 to 10, approximately 0.06 to 10, approximately 0.08 to 10, approximately 0.1 to 10, approximately 0.2 to 10, approximately 0.4 to 10, approximately 0.6 to 10, approximately 0.8 to 10, approximately 1 to 10, approximately 1.5 to 10, approximately 2 to 10, approximately 2.5 to 10, approximately 3 to 10, approximately 3.5 to 10, approximately 4 to 10, approximately 4.5 to 10, approximately The catalyst composition according to claim 1, wherein the values ​​are 5 to about 10, about 0.01 to about 8, about 0.01 to about 7, about 0.01 to about 6, about 0.01 to about 5, about 0.01 to about 4, about 0.01 to about 3, about 0.01 to about 2, about 0.01 to about 1, about 0.01 to about 0.5, about 0.01 to about 0.25, about 0.01 to about 0.2, about 0.01 to about 0.1, or about 0.01 to about 0.

05.

15. The catalyst composition according to claim 1, wherein g is about 0.01 to about 0.2, about 0.02 to about 0.2, about 0.04 to about 0.2, about 0.06 to about 0.2, about 0.08 to about 0.2, or about 0.1 to about 0.

2.

16. The catalyst composition according to claim 1, wherein g is about 0 to about 0.15, about 0 to about 0.1, about 0 to about 0.05, about 0 to about 0.04, about 0 to about 0.03, about 0 to about 0.02, or about 0 to about 0.

01.

17. The catalyst composition according to claim 1, wherein A is selected from the group consisting of potassium, rubidium, and cesium.

18. The catalyst composition according to claim 1, wherein A is selected from the group consisting of rubidium and cesium.

19. The catalyst composition according to claim 1, further comprising a support.

20. The catalyst composition according to claim 19, wherein the support constitutes about 30% to about 70% by mass, about 35% to about 70% by mass, about 40% to about 70% by mass, about 40% to about 65% by mass, about 40% to about 60% by mass, about 40% to about 55% by mass, or about 45% to about 55% by mass of the catalyst composition.

21. A method for ammoxidation of an olefin, comprising the step of reacting the olefin with a molecular oxygen-containing gas and ammonia in the gas phase, at high temperature and high pressure, in the presence of a catalyst composition according to any one of claims 1 to 20.

22. The method according to claim 21, wherein the olefin is selected from the group consisting of propylene, isobutylene, or mixtures thereof, so as to produce a reaction product comprising acrylonitrile, methacrylonitrile, and mixtures thereof.

23. The method according to claim 21, wherein the molar ratio of ammonia to olefin is about 0.5:1 to about 2:1, about 0.5:1 to about 1.5:1, about 0.5:1 to about 1.4:1, about 0.5:1 to about 1.3:1, about 0.5:1 to about 1.2:1, about 0.5:1 to about 1.1:1, about 0.5:1 to about 1:1, or about 0.75:1 to about 1:

1.

24. The method according to claim 21, wherein the olefin contains propylene, and the molar ratio of ammonia to propylene is about 0.9:1 to about 1.3:1, about 0.9:1 to about 1.2:1, about 0.9:1 to about 1.1:1, about 1:1 to about 1.1:1, or about 1:1 to about 1.05:

1.

25. The method according to claim 21, wherein the olefin contains propylene, the oxygen source contains air, and the molar ratio of air to propylene is about 5:1 to about 20:1, about 5:1 to about 15:1, about 6:1 to about 12:1, about 7:1 to about 15:1, about 8:1 to about 15:1, about 8:1 to about 14:1, about 8:1 to about 13:1, or about 8:1 to about 12:

1.

26. The method according to claim 21, wherein the olefin contains propylene, and the olefin conversion is approximately 85% or more, approximately 86% or more, approximately 87% or more, approximately 88% or more, approximately 89% or more, approximately 90% or more, approximately 91% or more, approximately 92% or more, approximately 93% or more, approximately 94% or more, approximately 95% or more, approximately 96% or more, approximately 97% or more, approximately 98% or more, approximately 99% or more, approximately 99.1% or more, approximately 99.2% or more, approximately 99.3% or more, approximately 99.7% or more, approximately 99.8% or more, approximately 99.6% or more, approximately 99.7% or more, approximately 99.8% or more, or approximately 99.9% or more.

27. The method according to claim 21, wherein the olefin contains propylene and the nitrile yield is about 70% or more, about 72% or more, about 74% or more, about 76% or more, about 78% or more, about 80% or more, about 82% or more, about 84% or more, about 86% or more, about 88% or more, or about 90% or more.