Catalyst for producing monocyclic aromatic hydrocarbons, and method for producing monocyclic aromatic hydrocarbons

Abstract

A catalyst for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon number from a feedstock oil having a 10 volume % distillation temperature of at least 140° C. and an end point temperature of not more than 400° C., or a feedstock oil having a 10 volume % distillation temperature of at least 140° C. and a 90 volume % distillation temperature of not more than 360° C., wherein the catalyst contains a crystalline aluminosilicate, gallium and/or zinc, and phosphorus, and the amount of phosphorus supported on the crystalline aluminosilicate is within a range from 0.1 to 1.9% by mass based on the mass of the crystalline aluminosilicate; and a method for producing monocyclic aromatic hydrocarbons, the method involving bringing a feedstock oil having a 10 volume % distillation temperature of at least 140° C. and an end point temperature of not more than 400° C., or a feedstock oil having a 10 volume % distillation temperature of at least 140° C. and a 90 volume % distillation temperature of not more than 360° C., into contact with the above-mentioned catalyst for producing monocyclic aromatic hydrocarbons.

Claims

1. A method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon number, the method comprising bringing a feedstock oil containing polycyclic aromatic hydrocarbons and having a 10 volume % distillation temperature of at least 140° C. and an end point temperature of not more than 400° C., or a feedstock oil containing polycyclic aromatic hydrocarbons and having a 10 volume % distillation temperature of at least 140° C. and a 90 volume % distillation temperature of not more than 360° C., into contact with a catalyst comprising a medium pore size zeolite, gallium and/or zinc, and phosphorus, wherein the amount of phosphorus supported on the medium pore size zeolite is within a range from 0.1 to 1.9% by mass based on the mass of the medium pore size zeolite.

2. The method according to claim 1, wherein a cracked gas oil produced in a fluid catalytic cracking is used as the feedstock oil.

3. The method according to claim 1, wherein the feedstock oil is brought into contact with the catalyst in a fluidized bed reactor.

4. The method according to claim 1, wherein the medium pore size zeolite is a pentasil-type zeolite.

5. The method according to claim 1, wherein the medium pore size zeolite is an MFI-type zeolite.

6. A method for producing monocyclic aromatic hydrocarbons of 6 to 8 carbon number, the method comprising bringing a feedstock oil containing polycyclic aromatic hydrocarbons and having a 10 volume % distillation temperature of at least 140° C. and an end point temperature of not more than 400° C., or a feedstock oil containing polycyclic aromatic hydrocarbons and having a 10 volume % distillation temperature of at least 140° C. and a 90 volume % distillation temperature of not more than 360° C., into contact with a catalyst comprising a medium pore size zeolite, gallium and/or zinc, and phosphorus, wherein the amount of phosphorus is within a range from 0.1 to 5.0% by mass based on the mass of the catalyst.

7. The method according to claim 6, wherein a cracked gas oil produced in a fluid catalytic cracking is used as the feedstock oil.

8. The method according to claim 6, wherein the feedstock oil is brought into contact with the catalyst in a fluidized bed reactor.

9. The method according to claim 6, wherein the medium pore size zeolite is a pentasil-type zeolite.

10. The method according to claim 6, wherein the medium pore size zeolite is an MFI-type zeolite.

Description

EXAMPLES

(1) The present invention is described in more detail below based on a series of examples and comparative examples, but the present invention is in no way limited by these examples.

Catalyst Preparation Example 1

(2) A solution (A) composed of 1706.1 g of sodium silicate (J Sodium Silicate No. 3, SiO.sub.2: 28 to 30% by mass, Na: 9 to 10% by mass, remainder: water, manufactured by Nippon Chemical Industrial Co., Ltd.) and 2227.5 g of water, and a solution (B) composed of 64.2 g of Al.sub.2(SO.sub.4).sub.3.14˜18H.sub.2O (special reagent grade, manufactured by Wako Pure Chemical Industries, Ltd.), 369.2 g of tetrapropylammonium bromide, 152.1 g of H.sub.2SO.sub.4 (97% by mass), 326.6 g of NaCl and 2975.7 g of water were prepared independently.

(3) Subsequently, with the solution (A) undergoing continuous stirring at room temperature, the solution (B) was added gradually to the solution (A). The resulting mixture was stirred vigorously for 15 minutes using a mixer, thereby breaking up the gel and forming a uniform fine milky mixture.

(4) This mixture was placed in a stainless steel autoclave, and a crystallization operation was performed under conditions including a temperature of 165° C., a reaction time of 72 hours, a stirring rate of 100 rpm, and under self-generated pressure. Following completion of the crystallization operation, the product was filtered, the solid product was recovered, and an operation of washing the solid product and then performing filtration was repeated 5 times, using a total of approximately 5 liters of deionized water in the 5 times of operations. The solid material obtained upon the final filtration was dried at 120° C., and was then calcined under a stream of air at 550° C. for 3 hours.

(5) Analysis of the resulting calcined product by X-ray diffraction (apparatus model: Rigaku RINT-2500V) confirmed that the product had an MFI structure. Further, X-ray fluorescence analysis (apparatus model: Rigaku ZSX101e) revealed a SiO.sub.2/Al.sub.2O.sub.3 ratio (molar ratio) of 64.8. Based on these results, the amount of aluminum element incorporated within the lattice framework was calculated as 1.32% by mass.

(6) A 30% by mass aqueous solution of ammonium nitrate was added to the calcined product in a ratio of 5 mL of the aqueous solution per 1 g of the calcined product, and after heating at 100° C. with constant stirring for 2 hours, the mixture was filtered and washed with water. This operation was performed 4 times in total, and the product was then dried for 3 hours at 120° C., yielding an ammonium-type crystalline aluminosilicate. Subsequently, the product was calcined for 3 hours at 780° C., yielding a proton-type crystalline aluminosilicate.

(7) Next, 120 g of the obtained proton-type crystalline aluminosilicate was impregnated with 120 g of an aqueous solution of gallium nitrate in order to support 0.2% by mass of gallium (based on a value of 100% for the total mass of the crystalline aluminosilicate), and the resulting product was then dried at 120° C. Subsequently, the product was calcined for 3 hours at 780° C. under a stream of air, yielding a gallium-supporting crystalline aluminosilicate.

(8) Subsequently, 30 g of the obtained gallium-supporting crystalline aluminosilicate was impregnated with 30 g of an aqueous solution of diammonium hydrogen phosphate in order to support 0.2% by mass of phosphorus on the aluminosilicate (based on a value of 100% for the total mass of the crystalline aluminosilicate), and the resulting product was then dried at 120° C. Subsequently, the product was calcined for 3 hours at 780° C. under a stream of air, yielding a catalyst containing the crystalline aluminosilicate, gallium and phosphorus.

(9) Tablet molding was performed by applying a pressure of 39.2 MPa (400 kgf) to the obtained catalyst, and the resulting tablets were subjected to coarse crushing and then classified using a 20 to 28 mesh size, thus yielding a granular catalyst 1 (hereinafter referred to as the “granulated catalyst 1”).

Catalyst Preparation Example 2

(10) With the exception of impregnating the gallium-supporting crystalline aluminosilicate with 30 g of an aqueous solution of diammonium hydrogen phosphate that had been prepared with a concentration sufficient to support 0.7% by mass of phosphorus on the aluminosilicate (based on a value of 100% for the total mass of the crystalline aluminosilicate), a granular catalyst 2 (hereinafter referred to as the “granulated catalyst 2”) was obtained in the same manner as that described in catalyst preparation example 1.

Catalyst Preparation Example 3

(11) With the exception of impregnating the gallium-supporting crystalline aluminosilicate with 30 g of an aqueous solution of diammonium hydrogen phosphate so as to support 1.2% by mass of phosphorus on the aluminosilicate (based on a value of 100% for the total mass of the crystalline aluminosilicate), a granular catalyst 3 (hereinafter referred to as the “granulated catalyst 3”) was obtained in the same manner as that described in catalyst preparation example 1.

Catalyst Preparation Example 4

(12) 18 g of fumed silica was impregnated with 30 g of an aqueous solution of diammonium hydrogen phosphate so as to incorporate 8.2% by mass of phosphorus within the silica, and the resulting product was dried at 120° C. Subsequently, the product was calcined for 3 hours at 780° C. under a stream of air, yielding a phosphorus-containing fumed silica. 18 g of this phosphorus-containing fumed silica was mixed with 12 g of the catalyst prepared in catalyst preparation example 2, the thus obtained catalyst was subjected to tablet molding by applying a pressure of 39.2 MPa (400 kgf), and the resulting tablets were subjected to coarse crushing and then classified using a 20 to 28 mesh size, thus yielding a granular catalyst 4 (hereinafter referred to as the “granulated catalyst 4”).

Catalyst Preparation Example 5

(13) With the exceptions of impregnating 120 g of the proton-type crystalline aluminosilicate with 30 g of an aqueous solution of zinc nitrate hexahydrate that had been prepared with a concentration sufficient to support 0.2% by mass of zinc on the aluminosilicate (based on a value of 100% for the total mass of the crystalline aluminosilicate), thus yielding a zinc-supporting crystalline aluminosilicate, and impregnating the zinc-supporting crystalline aluminosilicate with 30 g of an aqueous solution of diammonium hydrogen phosphate that had been prepared with a concentration sufficient to support 0.7% by mass of phosphorus on the aluminosilicate (based on a value of 100% for the total mass of the crystalline aluminosilicate), a granular catalyst 5 (hereinafter referred to as the “granulated catalyst 5”) was obtained in the same manner as that described in catalyst preparation example 1.

Catalyst Preparation Example 6

(14) A mixed solution containing 106 g of sodium silicate (J Sodium Silicate No. 3, SiO.sub.2: 28 to 30% by mass, Na: 9 to 10% by mass, remainder: water, manufactured by Nippon Chemical Industrial Co., Ltd.) and pure water was added dropwise to a dilute sulfuric acid solution to prepare a silica sol aqueous solution (SiO.sub.2 concentration: 10.2%). Meanwhile, distilled water was added to 20.4 g of the catalyst prepared in catalyst preparation example 2 and containing a crystalline aluminosilicate, gallium and phosphorus to prepare a zeolite slurry. The zeolite slurry was mixed with 300 g of the silica sol aqueous solution, and the resulting slurry was spray dried at 250° C., yielding a spherically shaped catalyst. Subsequently, the catalyst was calcined for 3 hours at 600° C., yielding a powdered catalyst 6 (hereinafter referred to as the “powdered catalyst 6”) having an average particle size of 85 μm and a bulk density of 0.75 g/cc.

Catalyst Preparation Example 7

(15) With the exception of impregnating the gallium-supporting crystalline aluminosilicate with 30 g of an aqueous solution of diammonium hydrogen phosphate so as to support 2.0% by mass of phosphorus on the aluminosilicate (based on a value of 100% for the total mass of the crystalline aluminosilicate), a granular catalyst 7 (hereinafter referred to as the “granulated catalyst 7”) was obtained in the same manner as that described in catalyst preparation example 1.

Catalyst Preparation Example 8

(16) With the exception of not impregnating the gallium-supporting crystalline aluminosilicate with an aqueous solution of diammonium hydrogen phosphate, a granular catalyst 8 (hereinafter referred to as the “granulated catalyst 8”) was obtained in the same manner as that described in catalyst preparation example 1.

(17) The initial reaction catalytic activity and the catalytic activity following hydrothermal degradation of the thus obtained granulated catalysts and powdered catalyst were evaluated using the methods outlined below.

(18) [Evaluation of Initial Reaction Catalytic Activity: Evaluation 1]

(19) Using a circulating reaction apparatus in which the reactor had been charged with a granulated catalyst (10 ml), a feedstock oil having the properties shown in Table 1 was brought into contact with the granulated catalyst and reacted under conditions including a reaction temperature of 550° C. and a reaction pressure of 0 MPaG. During the reaction, nitrogen was introduced as a diluent so that the contact time between the feedstock oil and the granulated catalyst was 7 seconds.

(20) Reaction was continued under these conditions for 30 minutes to produce monocyclic aromatic hydrocarbons of 6 to 8 carbon number, and a compositional analysis of the products was performed using an FID gas chromatograph connected directly to the reaction apparatus in order to evaluate the initial reaction reactivity. The evaluation results are shown in Table 2.

(21) Within the products shown in Table 2, the heavy fraction refers to hydrocarbons of 6 or more carbon number other than the monocyclic aromatic hydrocarbons of 6 to 8 carbon number, the light naphtha refers to hydrocarbons of 5 or 6 carbon number, the liquefied petroleum gas refers to hydrocarbons of 3 or 4 carbon number, and the cracked gas refers to hydrocarbons of not more than 2 carbon number.

(22) [Measurement of Yield of Monocyclic Aromatic Hydrocarbons in Initial Reaction: Evaluation 2]

(23) Using a circulating reaction apparatus in which the reactor had been charged with a powdered catalyst (400 g), a feedstock oil having the properties shown in Table 1 was brought into contact with the powdered catalyst and reacted under conditions including a reaction temperature of 550° C. and a reaction pressure of 0.1 MPaG. For the reaction, the powdered catalyst was packed in a reaction tube with a diameter of 60 mm. During the reaction, nitrogen was introduced as a diluent so that the contact time between the feedstock oil and the powdered catalyst was 10 seconds.

(24) Reaction was continued under these conditions for 10 minutes to produce monocyclic aromatic hydrocarbons of 6 to 8 carbon number, and a compositional analysis of the products was performed using an FID gas chromatograph connected directly to the reaction apparatus in order to evaluate the initial reaction reactivity. The evaluation results are shown in Table 2.

(25) Within the products shown in Table 2, the heavy fraction refers to hydrocarbons of 6 or more carbon number other than the monocyclic aromatic hydrocarbons of 6 to 8 carbon number, the light naphtha refers to hydrocarbons of 5 or 6 carbon number, the liquefied petroleum gas refers to hydrocarbons of 3 or 4 carbon number, and the cracked gas refers to hydrocarbons of not more than 2 carbon number.

(26) [Evaluation of Catalytic Activity Following Hydrothermal Degradation: Evaluation 3]

(27) The granulated catalysts 1 to 5 and 8 and the powdered catalyst 6 were each subjected to a hydrothermal treatment under conditions including a treatment temperature of 650° C. and a treatment time of 6 hours in a 100% by mass steam atmosphere, thus preparing pseudo-degraded catalysts 1 to 6 and 8 that had undergone a simulated hydrothermal degradation.

(28) With the exception of using these pseudo-degraded catalysts 1 to 5 and 8 instead of the granulated catalysts 1 to 5 and 8, the same process as that described for evaluation 1 was used to react the feedstock oil and then perform a compositional analysis of the resulting products to evaluate the catalytic activity following hydrothermal degradation. The evaluation results are shown in Table 2.

(29) Further, with the exception of using the pseudo-degraded catalyst 6 instead of the powdered catalyst 6, the same process as that described for evaluation 2 was used to react the feedstock oil and then perform a compositional analysis of the resulting products to evaluate the catalytic activity following hydrothermal degradation. The evaluation results are shown in Table 2.

(30) [Catalyst Degradation]

(31) A value was calculated for the ratio of the amount (% by mass) of monocyclic aromatic hydrocarbons of 6 to 8 carbon number in the catalytic activity evaluation following hydrothermal degradation (evaluation 3) relative to the amount (% by mass) of monocyclic aromatic hydrocarbons of 6 to 8 carbon number in the initial reaction catalytic activity evaluation (evaluation 1 or evaluation 2) (namely, [amount (% by mass) of monocyclic aromatic hydrocarbons of 6 to 8 carbon number in evaluation 3]/[amount (% by mass) of monocyclic aromatic hydrocarbons of 6 to 8 carbon number in evaluation 1 or evaluation 2]), and this value was used to determine the degree of catalyst degradation. The results are summarized in Table 2. A larger value for this property indicates superior resistance to catalyst degradation.

(32) TABLE-US-00001 TABLE 1 Analysis Feedstock properties method Density (Measurement g/cm.sup.3 0.906 JIS K 2249 temperature: 15° C.) Kinematic viscosity mm.sup.2/s 3.640 JIS K 2283 (Measurement temperature: 30° C.) Distillation Initial boiling point ° C. 175.5 JIS K2254 character- 10 volume % ° C. 224.5 istics distillation temperature 50 volume % ° C. 274.0 distilintion temperature 90 volume % ° C. 349.5 distilintion temperature End point temperature ° C. 376.0 Composi- Saturated content volume % 35 JPI-5S-49 tional Olefin content volume % 8 analysis Total aromatic content volume % 57 Monocyclic aromatic volume % 23 content Bicyclic aromatic volume % 25 content Triyclic and higher volume % 9 aromatic content

(33) TABLE-US-00002 TABLE 2 Granulated catalyst preparation method Example 1 Example 2 Example 3 Example 4 Amount of phosphorus within crystalline 0.2 0.7 1.2 0.7 aluminosilicate (% by mass) Evaluation test Evalua- Evalua- Evalua- Evalua- Evalua- Evalua- Evalua- Evalua- tion 1 tion 3 tion 1 tion 3 tion 1 tion 3 tion 1 tion 3 Catalyst Granulated Pseudo- Granulated Pseudo- Granulated Pseudo- Granulated Pseudo- catalyst 1 degraded catalyst 2 degraded catalyst 3 degraded catalyst 4 degraded catalyst 1 catalyst 2 catalyst 3 catalyst 4 Products Heavy fraction 48 55 49 52 54 54 53 53 (% by mass) Monocyclic aromatic 43 31 38 34 26 27 32 29 hydrocarbons of 6 to 8 carbon atoms Light naphtha 0 0 0 0 1 0 0 0 Liquefied petroleum gas 1 6 5 5 11 10 6 9 Cracked gas 5 7 7 7 8 8 8 8 Hydrogen 2 1 1 1 1 1 1 1 [Amount (% by mass) of monocyclic 0.72 0.91 1.05 0.91 aromatic hydrocarbons in evaluation 3]/[amount (% by mass) of monocyclic aromatic hydrocarbons in evaluation 1 or evaluation 2] Comparative Comparative Granulated catalyst preparation method Example 5 example 1 example 2 Amount of phosphorus within crystalline 0.7 2.0 0 aluminosilicate (% by mass) Evaluation test Evalua- Evalua- Evalua- Evalua- Evalua- Evalua- tion 2 tion 3 tion 1 tion 3 tion 1 tion 3 Catalyst Powdered Pseudo- Granulated — Granulated Pseudo- catalyst 6 degraded catalyst 7 catalyst 8 degraded catalyst 6 catalyst 8 Products Heavy fraction 50 52 60 — 48 64 (% by mass) Monocyclic aromatic 35 32 5 — 42 14 hydrocarbons of 6 to 8 carbon atoms Light naphtha 0 0 5 — 0 3 Liquefied petroleum gas 6 7 22 — 2 12 Cracked gas 8 8 7 — 6 6 Hydrogen 1 1 0 — 2 1 [Amount (% by mass) of monocyclic 0.91 — 0.33 aromatic hydrocarbons in evaluation 3]/[amount (% by mass) of monocyclic aromatic hydrocarbons in evaluation 1 or evaluation 2] Evaluation 1 or evaluation 2: Initial reaction catalytic activity Evaluation 3: Catalytic activity following hydrothermal degradation
[Results]

(34) Examples 1 to 6, which employed the granulated catalysts 1 to 5 and the powdered catalyst 6 respectively, exhibited favorable initial reaction catalytic activity and favorable catalytic activity following hydrothermal degradation, and the monocyclic aromatic hydrocarbons of 6 to 8 carbon number which are objective products in the present embodiment were able to be obtained in high yield, both during the initial reaction and following hydrothermal degradation.

(35) On the other hand, the results for Comparative Example 1 revealed that if a large amount of phosphorus is added, then the yield of monocyclic aromatic hydrocarbons of 6 to 8 carbon number decreases markedly, even during the initial reaction.

(36) The results for Comparative Example 2 revealed that if a catalyst with no phosphorus supported thereon is used, despite the yield of monocyclic aromatic hydrocarbons of 6 to 8 carbon number is favorable during the initial reaction, the yield decreases significantly following hydrothermal degradation, and the deterioration in the catalyst is marked, making the catalyst impractical.