Method for reactivating used hydrogenation treatment titania catalyst, and regenerated hydrogenation treatment titania catalyst

Abstract

Provided is a method of reactivating a used titania catalyst for hydrogenation treatment, capable of improving the catalytic activity of the used titania catalyst for hydrogenation treatment that is obtained by supporting a catalyst component on a titania support and exhibits reduced catalytic activity after having been used for hydrogenation treatment of a hydrocarbon oil, to a level comparable to that of a newly prepared fresh titania catalyst before use. The method of reactivating a used titania catalyst for hydrogenation treatment, the used titania catalyst for hydrogenation treatment being obtained by supporting a catalyst component on a titania support and exhibiting reduced catalytic activity after having been used for hydrogenation treatment of a hydrocarbon oil, includes: a coke removal step of removing a carbonaceous component on a surface of the used catalyst by heating the catalyst in an oxygen-containing gas atmosphere; an impregnation step of impregnating the carbonaceous component-removed catalyst obtained by the coke removal step with a saccharide-containing solution; and a drying step of drying the saccharide-impregnated catalyst obtained by the impregnation step, to obtain a catalyst in which a saccharide is supported.

Claims

1. A method of reactivating a used titania catalyst for hydrogenation treatment, the method comprising: obtaining a titania-coated alumina support comprising an alumina hydrate particle and a titania coating layer formed on a surface of the alumina hydrate particle between an isoelectric point of aluminum oxide and an isoelectric point of titanium oxide by coating the alumina hydrate particle with the titania coating layer in a condition of 5.00.1 of a pH, wherein the titania-coated alumina support does not have an anatase crystal form of titania as detected by X-ray diffraction; supporting a catalyst component and a saccharide on the titania-coated alumina support to obtain a fresh titania catalyst supported on the titania-coated alumina support; conducting hydrogenation treatment of a hydrocarbon oil in the presence of the fresh titania catalyst supported on the titania-coated alumina support, thereby resulting in a used titania catalyst supported on the titania-coated alumina support, and a carbonaceous component deposited on a surface of the used titania catalyst; and then subjecting the used titania catalyst supported on the titania-coated alumina support to a reactivation process, wherein the reactivation process comprises: a coke removal step of removing the carbonaceous component on the surface of the used catalyst supported on the titania-coated alumina support by heating the catalyst in an oxygen-containing gas atmosphere; an impregnation step of impregnating the carbonaceous component-removed catalyst obtained by the coke removal step with a saccharide-containing solution in a pH region that a zeta potential of titania is 0 or less; and a drying step of drying the saccharide-impregnated catalyst obtained by the impregnation step to obtain a catalyst in which a saccharide is supported.

2. The method of reactivating a used titania catalyst for hydrogenation treatment according to claim 1, wherein the catalyst component comprises at least one kind of periodic table group VI metal compound, at least one kind of periodic table group VIII to X metal compound, and at least one kind of phosphorus compound.

3. The method of reactivating a used titania catalyst for hydrogenation treatment according to claim 1, wherein the saccharide-containing solution to be used in the impregnation step comprises a solution containing one kind or two or more kinds of saccharides selected from the group consisting of glucose, fructose, erythritol, xylose, xylitol, sorbitol, mannitol, invert sugar, maltose, trehalose, maltitol, isomerized sugar, and raffinose.

4. The method of reactivating a used titania catalyst for hydrogenation treatment according to claim 1, wherein the saccharide-containing solution to be used in the impregnation step comprises a solution containing, in addition to the saccharide, a catalyst component comprising at least one kind of periodic table group VI metal compound, at least one kind of periodic table group VIII to X metal compound, and at least one kind of phosphorus compound.

5. The method of reactivating a used titania catalyst for hydrogenation treatment according to claim 4, wherein the catalyst component contained in the saccharide-containing solution comprises the same catalyst component as the catalyst component supported on the titania support of the titania catalyst for hydrogenation treatment.

6. The method of reactivating a used titania catalyst for hydrogenation treatment according to claim 4 or 5, wherein a total amount of the periodic table group VI metal compound, the periodic table group VIII to X metal compound, and the phosphorus compound, in the catalyst component contained in the saccharide-containing solution, is 5 mass % or less with respect to a catalyst component of a regenerated titania catalyst for hydrogenation treatment after reactivation, in terms of an oxide.

7. The method of reactivating a used titania catalyst for hydrogenation treatment according to claim 1, wherein the oxygen-containing gas to be used in the coke removal step comprises air.

8. The method of reactivating a used titania catalyst for hydrogenation treatment according to claim 1, wherein the impregnation step of impregnating the carbonaceous component-removed catalyst obtained by the coke removal step with a saccharide-containing solution is in a weakly acidic region of from pH 3 to 7.

Description

DESCRIPTION OF EMBODIMENTS

(1) Embodiments of the present invention are hereinafter described in detail on the basis of Examples, Reference Examples, and Comparative Examples. It should be noted that various physical properties, catalyst performance, and the like were measured under the following procedures and conditions in Examples, Reference Examples, and Comparative Examples described below.

(2) [Treatment Before Measurement]

(3) Upon measurement of various physical properties, an object to be measured was preliminarily subjected to calcination treatment under the conditions of 500 C. and 3 hours, and then analyzed.

(4) [Measurement of Pore Distribution and Pore Volume]

(5) The pore distribution and pore volume of a catalyst or a support were measured by mercury porosimetry through pressurization up to a measurement pressure of 414 MPa using AutoPore IV9520 manufactured by SHIMADZU CORPORATION.

(6) [Pore Sharpness Degree]

(7) The pore sharpness degree is a numerical value that specifies the uniformity of a pore size. Herein, a pore sharpness degree closer to 100% means that the pore size of a catalyst or a support is more fully uniform. Specifically, a pore size corresponding to 50% cumulative pore volume (median size) is determined, and then, a partial pore volume (PVM) of ones in the pore size range of 5% of the logarithmic value of the median size is determined. The pore sharpness degree is determined by the following equation based on the partial pore volume (PVM) and the pore volume (PVT). That is, the pore sharpness degree can be calculated by the following equation based on a cumulative pore distribution curve measured by mercury porosimetry.
Pore sharpness degree (%)=(PVM/PVT)100

(8) [Desulfurization Test of Gas Oil]

(9) A hydrodesulfurization test of gas oil for measuring the desulfurization activity of a hydrogenation treatment catalyst was performed as described below.

(10) The hydrodesulfurization test was performed by using a high-pressure fixed-bed flow reactor and loading 15 ml of a catalyst under the conditions of: reaction pressure: 5 MPa; reaction temperature: 340 C.; liquid hourly space velocity: 1.5 h.sup.1; and volume ratio of hydrogen/raw material: 250 N1/1. All the catalysts for hydrogenation treatment subjected to the test were preliminarily subjected to sulfurization treatment (pre-sulfurization) using gas oil having a sulfur concentration adjusted to 2.5% (in terms of mass) through addition of dimethyl disulfide. Straight-run gas oil from the Middle East subjected to the hydrodesulfurization test has the following properties: specific gravity (15/4 C.): 0.849; sulfur content: 1.21 mass %; nitrogen content: 96 ppm; and initial distillation temperature of 228 C., 50% distillation temperature of 293 C., and 90% distillation temperature of 347 C., as distillation properties.

(11) The desulfurization activity of the catalyst for hydrogenation treatment was determined as described below. The rate constant of a desulfurization reaction was determined on the assumption that the desulfurization reaction was a 1.2-order reaction, and an average value of the rate constants of the desulfurization reaction between a reaction time period of from 100 to 144 hours was calculated. Desulfurization activity relative to that of a catalyst for hydrogenation treatment of Reference Example 1 or Reference Example 2 described below was determined and represented as relative desulfurization activity, given that the average value of the rate constants of the desulfurization reaction in the case of a titania catalyst for hydrogenation treatment, HBT-1, in Reference Example 1 or an alumina catalyst for hydrogenation treatment, ALC-1, in Reference Example 2 was taken as 100.

(12) [Preparation of Titania Catalyst for Hydrogenation Treatment]

(13) <Preparation of Raw Material Solution>

(14) The following solutions were each prepared in the full amount required for the operations described below: solution A obtained by adding 1,030 g of water with respect to 970 g of aluminum chloride hexahydrate; solution B obtained by adding 1,000 g of water with respect to 1,000 g of 28% ammonia water; solution C obtained by adding water to 198 g of a titanium tetrachloride solution having a Ti concentration of 16.6 mass % and a Cl concentration of 32.3 mass %, to give a volume of 1.8 liters (L); solution D obtained by adding water to 231 g of 14% ammonia water, to give a volume of 1.8 L; and solution E obtained by adding 733 g of hydrochloric acid and 13 g of water to 1,520 g of a titanium tetrachloride solution having a Ti concentration of 16.7 mass % and a Cl concentration of 32.6 mass %.

REFERENCE EXAMPLE 1

(15) <Production of Alumina Hydrate Particle>

(16) (a) 14 L of water were loaded in an enamel vessel of 19 L, and heated to 80 C. while being stirred. 850 g of the solution A were added to the enamel vessel and the mixture was maintained for 5 minutes. The solution at this time (hereinafter referred to as synthetic solution) had a pH of 2.5. Next, the solution B was added to the enamel vessel in such an amount that the pH of the synthetic solution became 7.5, and the mixture was maintained for 5 minutes (first pH swing).

(17) (b) After that, 850 g of the solution A were added thereto to allow the pH of the synthetic solution to 3.0, and the mixture was maintained for 5 minutes. Then, the solution B was added thereto again in such an amount that the pH of the synthetic solution became 7.5, and the mixture was maintained for 5 minutes (second pH swing).

(18) (c) Then, a chlorine ion and an ammonium ion as impurities were removed by washing. Thus, alumina hydrate particles subjected to pH swing twice were obtained.

(19) <Production of Titania-Coated Alumina Support>

(20) 122 g of the obtained alumina hydrate particles were collected in terms of an oxide, and well stirred with a mixer while water was added thereto, to provide 8 L of a dispersion. While the dispersion was maintained at 60 C., the solution C was added thereto to adjust the pH to 5.0. Then, the solution C and the solution D each in an amount of 1.8 L were added thereto simultaneously over about 2 hours so that the pH was continuously maintained within a range of 5.00.1. Thus, titania-coated alumina hydrate particles were produced. The coating amount of titania in the obtained titania-coated alumina hydrate particles is 31%.

(21) An ammonia ion and a chlorine ion coexisting with the titania-coated alumina hydrate particles thus obtained were removed by washing with water. Filtration was performed to achieve a water content rate allowing for forming. The resultant was formed into a cylindrical shape having a diameter of 1.2 mm through extrusion molding (forming step), followed by drying at 120 C. for 16 hours and further calcination at 500 C. for 3 hours (first drying step). Thus, a titania-coated alumina support was obtained.

(22) The obtained titania-coated alumina support was measured for the specific surface area and the pore distribution, and subjected to X-ray diffraction.

(23) As a result, it was found that the specific surface area was 400 m.sup.2/g, the pore volume was 0.57 ml/g, and the pore sharpness degree was 76.5%. In addition, there was detected no titania in an anatase crystal form.

(24) <Production of Titania Catalyst>

(25) 34.5 g of molybdenum oxide, 7.7 g of cobalt carbonate in terms of CoO, and 5.0 g of 85% phosphoric acid were added to water, and dissolved through heating while being stirred. Thus, a catalyst component aqueous solution having a total weight adjusted to 100.0 g was obtained. Further, 4.3 g of sorbitol were dissolved in 27.6 g of the obtained catalyst component aqueous solution. Thus, an aqueous solution containing a catalyst component was obtained.

(26) 30.0 g of the titania-coated alumina support obtained above were impregnated with the aqueous solution containing a catalyst component, followed by drying at 120 C. for 12 hours. Thus, a titania catalyst for hydrogenation treatment, HBT-1, was obtained.

(27) It was found that the obtained titania catalyst for hydrogenation treatment had a specific surface area of 232 m.sup.2/g, a pore volume of 0.36 ml/g, and a pore sharpness degree of 70.2%.

(28) A hydrodesulfurization test of gas oil using the obtained catalyst was performed under the reaction conditions described above. The average value of the rate constants of the desulfurization reaction was taken as 100, and used as a standard for evaluation of the catalytic activity (relative desulfurization activity) of regenerated titania catalysts for hydrogenation treatment (hereinafter referred to as regenerated catalyst) obtained in Examples 1 to 5 and Comparative Examples 1 to 3 described below.

(29) [Regeneration of Used Titania Catalyst for Hydrogenation Treatment]

[EXAMPLE 1]

(30) The used titania catalyst for hydrogenation treatment HBT-1 recovered after operation in a hydrodesulfurization apparatus for gas oil for about 1 year was washed with a toluene solvent to remove an oil content. Then, the resultant was dried at 120 C. for 10 hours in an air atmosphere to remove the solvent. At this time, the catalyst contained 14.7 wt % of a carbon content and 8.5 wt % of a sulfur content.

(31) The catalyst after the drying treatment was subjected to coke removal treatment (coke removal step) by rotating the catalyst in a rotary calcination furnace with keeping the furnace temperature at 350 C. for 3 hours and then gradually elevating the temperature and keeping the furnace temperature at 500 C. for 3 hours, while allowing a low oxygen concentration gas having an oxygen concentration of 2.0% obtained through dilution of air with nitrogen to flow into the furnace. It was found that the catalyst after the calcination treatment contained 0.87% of a carbon content and 0.62% of a sulfur content. The catalyst after the coke removal treatment was represented as RHBT-1.

(32) 30 g of the catalyst RHBT-1 after the coke removal treatment were impregnated with sorbitol by using an aqueous solution containing 22.1 wt % of sorbitol so that the content of sorbitol was 10 wt % with respect to the catalyst. Then, the resultant was dried at 120 C. for 3 hours. Thus, a regenerated catalyst RHBT-2 was obtained.

[EXAMPLE 2]

(33) 30 g of the catalyst RHBT-1 after the coke removal treatment were impregnated with sorbitol by using an aqueous solution containing 22.5 wt % of glucose so that the content of glucose was 10 wt % with respect to the catalyst. Then, the resultant was dried at 120 C. for 3 hours. Thus, a regenerated catalyst RHBT-3 was obtained.

[EXAMPLE 3]

(34) 30 g of the catalyst RHBT-1 after the coke removal treatment were impregnated with sorbitol by using an aqueous solution containing 12.0 wt % of glucose so that the content of glucose was 5 wt % with respect to the catalyst. Then, the resultant was dried at 120 C. for 3 hours. Thus, a regenerated catalyst RHBT-4 was obtained.

[EXAMPLE 4]

(35) 30 g of the catalyst RHBT-1 after the coke removal treatment were impregnated with sorbitol by using an aqueous solution containing 21.9 wt % of sucrose so that the content of sucrose was 10 wt % with respect to the catalyst. Then, the resultant was dried at 120 C. for 3 hours. Thus, a regenerated catalyst RHBT-5 was obtained.

[EXAMPLE 5]

(36) 30 g of the catalyst RHBT-1 after the coke removal treatment were impregnated with sorbitol by using an aqueous solution containing 22.4 wt % of maltitol so that the content of maltitol was 10 wt % with respect to the catalyst. Then, the resultant was dried at 120 C. for 3 hours. Thus, a regenerated catalyst RHBT-6 was obtained.

[EXAMPLE 6]

(37) 30 g of the catalyst RHBT-1 after the coke removal treatment were impregnated with sorbitol by using an aqueous solution containing 22.4 wt % of sorbitol, and as a catalyst component, 4.5 g of molybdenum oxide in terms of MoO.sub.3, 0.8 g of cobalt carbonate in terms of CoO, and 0.7 g of phosphoric acid in terms of P.sub.2O.sub.5 so that the content of sorbitol was 10 wt % with respect to the catalyst. Then, the resultant was dried at 120 C. for 3 hours. Thus, a regenerated catalyst RHBT-9 was obtained.

[COMPARATIVE EXAMPLE 1]

(38) The catalyst RHBT-1 after the coke removal treatment obtained in Example 1 was taken as a regenerated catalyst of Comparative Example 1.

[COMPARATIVE EXAMPLE 2]

(39) The catalyst RHBT-1 after the coke removal treatment was impregnated in the same manner as in Example 1 so that the content of citric acid was 5 wt % and the content of polyethylene glycol was 5 wt %. Then, the resultant was dried at 120 C. for 3 hours. Thus, a regenerated catalyst RHBT-7 was obtained.

[COMPARATIVE EXAMPLE 3]

(40) The catalyst RHBT-1 after the coke removal treatment was impregnated in the same manner as in Example 1 so that the content of citric acid was 5 wt % and the content of glucose was 5 wt %. Then, the resultant was dried at 120 C. for 3 hours. Thus, a regenerated catalyst RHBT-8 was obtained.

(41) <Evaluation of Hydrodesulfurization Activity>

(42) For measuring the desulfurization activities of the regenerated catalysts obtained in Examples 1 to 6 and Comparative Examples 1 to 3 as a catalyst for hydrogenation treatment, the hydrodesulfurization test of gas oil described in the above-mentioned [Desulfurization test of gas oil] section was performed. The relative desulfurization activities were summarized in Table 1.

[REFERENCE EXAMPLE 2]

(43) An ammonia ion and a chlorine ion coexisting with the alumina hydrate particles obtained in the <Production of alumina hydrate particle> section in Reference Example 1 were removed by washing with water. Filtration was performed to achieve a water content rate allowing for forming. The resultant was formed into a cylindrical shape having a diameter of 1.2 mm through extrusion molding (forming step), followed by drying at 120 C. for 16 hours and further calcination at 500 C. for 3 hours (first drying step). Thus, an alumina support was obtained.

(44) The obtained alumina support was measured for the specific surface area and the pore distribution, and subjected to X-ray diffraction. As a result, it was found that the specific surface area was 346 m.sup.2/g, the pore volume was 0.5 ml/g, and the pore sharpness degree was 65.9%.

(45) <Production of Alumina Catalyst>

(46) 34.5 g of molybdenum oxide, 7.7 g of cobalt carbonate in terms of CoO, and 5.0 g of 85% phosphoric acid were added to water, and dissolved through heating while being stirred. Thus, a catalyst component aqueous solution having a total weight adjusted to 100.0 g was obtained. Further, 4.3 g of sorbitol were dissolved in 27.6 g of the obtained catalyst component aqueous solution. Thus, an aqueous solution containing a catalyst component was obtained.

(47) 30.0 g of the alumina support obtained above were impregnated with the aqueous solution containing a catalyst component, followed by drying at 120 C. for 12 hours. Thus, an alumina catalyst for hydrogenation treatment, ALC-1, was obtained.

(48) It was found that the obtained alumina catalyst for hydrogenation treatment had a specific surface area of 195m.sup.2/g, a pore volume of 0.35 ml/g, and a pore sharpness degree of 62.4%.

(49) A hydrodesulfurization test of gas oil using the obtained catalyst was performed under the reaction conditions described above. The average value of the rate constants of the desulfurization reaction was taken as 100, and used as a standard for evaluation of the catalytic activities (relative desulfurization activities) of regenerated catalysts obtained in Comparative Examples 4 to 6 described below.

(50) [Regeneration of Used Alumina Catalyst for Hydrogenation Treatment]

[COMPARATIVE EXAMPLE 4]

(51) The used alumina catalyst for hydrogenation treatment ALC-1 recovered after operation in a hydrodesulfurization apparatus for gas oil for about 1 year was washed with a toluene solvent to remove an oil content. Then, the resultant was dried at 120 C. for 10 hours in an air atmosphere to remove the solvent. At this time, the catalyst contained 16.7 wt% of a carbon content and 8.2 wt% of a sulfur content.

(52) The catalyst after the drying treatment was subjected to regeneration treatment by rotating the catalyst in a rotary calcination furnace with keeping the furnace temperature at 350 C. for 3 hours and then gradually elevating the temperature and keeping the furnace temperature at 500 C. for 3 hours, while allowing a low oxygen concentration gas having an oxygen concentration of 2.0% obtained through dilution of air with nitrogen to flow into the furnace. It w-s found that the catalyst after the calcination treatment contained 0.77% of a carbon content and 0.54% of a sulfur content. The regenerated catalyst was represented as RALC-1.

[COMPARATIVE EXAMPLE 5]

(53) 30 g of the regenerated catalyst RALC-1 were impregnated with sorbitol by using an aqueous solution containing 22.1 wt % of sorbitol so that the content of sorbitol was 10 wt % with respect to the catalyst. Then, the resultant was dried at 120 C. for 3 hours. Thus, a regenerated catalyst RALC-2 was obtained.

[COMPARATIVE EXAMPLE 6]

(54) 30 g of the regenerated catalyst RALC-1 were impregnated with sorbitol by using an aqueous solution containing 22.5 wt % of glucose so that the content of glucose was 10 wt % with respect to the catalyst. Then, the resultant was dried at 120 C. for 3 hours. Thus, a regenerated catalyst RALC-3 was obtained.

(55) <Evaluation of Hydrodesulfurization Activity>

(56) For measuring the desulfurization activities of the regenerated catalysts obtained in Comparative Examples 4 to 6 as a catalyst for hydrogenation treatment, the hydrodesulfurization test of gas oil described in the above-mentioned [Desulfurization test of gas oil] section was performed. The relative desulfurization activities were summarized in Table 2.

(57) TABLE-US-00001 TABLE 1 Additive in impregnation step Saccharide or Catalyst organic Catalyst Relative Kind of No. Acid additive component activity support Reference HBT-1 100 Titania- Example 1 coated Comparative RHBT-1 None None 52 Example 1 Example 1 RHBT-2 None Sorbitol 10 wt % 91 Example 2 RHBT-3 None Glucose 10 wt % 98 Example 3 RHBT-4 None Glucose 5 wt % 77 Example 4 RHBT-5 None Sucrose 10 wt % 88 Example 5 RHBT-6 None Maltitol 10 wt % 93 Example 6 RHBT-9 None Sorbitol 10 wt % Mo, Co, P 98 Comparative RHBT-7 Citric Polyethylene 61 Example 2 acid 5 wt % glycol 5 wt % Comparative RHBT-8 Citric Glucose 5 wt % 64 Example 3 acid 5 wt %

(58) TABLE-US-00002 TABLE 2 Additive in impregnation step Catalyst Saccharide or Relative Kind of No. Acid organic additive activity support Reference ALC-1 100 Alumina Example 2 Comparative RALC-1 None None 53 Example 4 Comparative RALC-2 None Sorbitol 10 wt % 62 Example 5 Comparative RALC-3 None Glucose 10 wt % 64 Example 6