Diagnostic method of hydro refining catalyst activity, and manufacturing method of base oil

Abstract

To provide a diagnostic method of hydro-refining catalyst activity capable of easily diagnosing the activity of a hydro-refining catalyst before the color of the base oil deteriorates.SOLUTION: The diagnostic method of hydro-refining catalyst activity is a diagnostic method used for manufacturing base oil. The activity of the hydro-refining catalyst is diagnosed based on the difference between the UV-visible absorption spectrum of base oil in which the Saybolt color produced using the hydro-refining catalyst is +28 or higher and the UV-visible absorption spectrum standard base oil in which the Saybolt color produced using the hydrorefining catalyst is +28 or higher.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a method for diagnosing the activity of a hydrorefining catalyst and a method for producing a base oil. [Background technology]

[0002] Some base oils provided as products are produced by hydrorefining using a hydrorefining catalyst (see, for example, Patent Document 1). Generally, the activity of a catalyst gradually decreases with use. This is no exception for hydrorefining catalysts. Since a decrease in the activity of a hydrorefining catalyst affects the quality of the base oil, it is important to understand the activity of the hydrorefining catalyst.

[0003] A widely used method for understanding the activity of hydrorefining catalysts is to periodically monitor the color of base oils. Other known methods include quantitative analysis of polycyclic aromatic compounds separated by gas chromatography or liquid chromatography. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2002-371286 A Summary of the Invention [Problem to be solved by the invention]

[0005] However, when the color of the base oil starts to deteriorate, the activity of the hydrorefining catalyst has already decreased significantly, so that recovery by adjusting the operating conditions is often difficult. Therefore, it is considered desirable to establish a method for diagnosing the activity of the hydrorefining catalyst before the color of the base oil starts to deteriorate. Although the method using gas chromatography or liquid chromatography is excellent in that it can diagnose the activity of the hydrorefining catalyst before the color of the base oil starts to deteriorate, it is difficult to adopt it as a method for routinely diagnosing the activity of the hydrorefining catalyst because the separation work of polycyclic aromatics is complicated.

[0006] Therefore, an object of the present invention is to provide a method for diagnosing the activity of a hydrorefining catalyst, which can simply and easily diagnose the activity of a hydrorefining catalyst before the color of the base oil deteriorates, and a method for producing a base oil using the diagnostic method. [Means for solving the problem]

[0007] According to the present invention, the following [1] and [2] are provided. [1] A method for diagnosing the activity of a hydrorefining catalyst used in the production of base oil, comprising: A diagnostic method for diagnosing activity of the hydrorefining catalyst based on the difference between the ultraviolet-visible absorption spectrum of a base oil having a Saybolt color of +28 or more produced using the hydrorefining catalyst and the ultraviolet-visible absorption spectrum of a standard base oil having a Saybolt color of +28 or more produced using the hydrorefining catalyst. [2] A method for producing a base oil, comprising a step of carrying out the diagnostic method described in [1] above. Effect of the Invention

[0008] According to the present invention, it is possible to provide a method for diagnosing the activity of a hydrorefining catalyst, which can simply and easily diagnose the activity of a hydrorefining catalyst before the color of a base oil deteriorates, and a method for producing a base oil using the diagnostic method. [Brief description of the drawings]

[0009] [Figure 1]FIG. 2 is a diagram showing an example of a spectrum of a base oil immediately after the start of use of a hydrorefining catalyst, and a spectrum of the base oil after a certain period of time has elapsed since the start of use of the hydrorefining catalyst. [Diagram 2] FIG. 1 shows the results of Example A. [Diagram 3] FIG. 1 shows the results of Example B. [Figure 4] FIG. 1 shows the results of Example C. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] The upper and lower limit values ​​of the numerical ranges described in this specification can be combined in any way. For example, when "A to B" and "C to D" are described as numerical ranges, the numerical ranges "A to D" and "C to B" are also included in the scope of the present invention. In addition, unless otherwise specified, a numerical range of "lower limit value to upper limit value" described in this specification means not less than the lower limit value and not more than the upper limit value.

[0011] [Method for diagnosing the activity of hydrorefining catalyst] The method for diagnosing the activity of a hydrorefining catalyst of this embodiment is a method for diagnosing the activity of a hydrorefining catalyst used in the production of base oil, and diagnoses the activity of the hydrorefining catalyst based on the difference between the ultraviolet-visible absorption spectrum of a base oil produced using the hydrorefining catalyst and having a Saybolt color of +28 or more, and the ultraviolet-visible absorption spectrum of a standard base oil produced using the hydrorefining catalyst and having a Saybolt color of +28 or more. In this specification, the Saybolt color refers to a value measured in accordance with JIS K2580:2003.

[0012] The present inventors have conducted extensive research to solve the above problems. As a result, they have found that base oils produced using a hydrorefining catalyst and having a Saybolt color of +28 or more (i.e., base oils whose hue has not deteriorated) undergo changes in the ultraviolet-visible absorption spectrum when the hydrorefining catalyst is used. The present inventors have found that by utilizing this phenomenon, the activity of the hydrorefining catalyst can be diagnosed based on the ultraviolet-visible absorption spectrum even for base oils produced using a hydrorefining catalyst and having a Saybolt color of +28 or more. After further research, they have completed the present invention.

[0013] The diagnostic method of this embodiment will be described in detail below.

[0014] <Base oil> In the diagnostic method of the present embodiment, the activity of a hydrorefining catalyst is diagnosed by using a base oil produced through a hydrorefining treatment using a hydrorefining catalyst. The base oil may, for example, be a mineral base oil produced through a hydrorefining process using a hydrorefining catalyst, and is preferably a mineral base oil classified as Group II or Group III in the American Petroleum Institute (API) base oil category.

[0015] The base oil is preferably a mineral base oil produced through hydrofinishing, which is a treatment carried out primarily for the purpose of improving the color of the base oil. The base oil may also be subjected to hydrotreating prior to hydrofinishing, which is a process carried out primarily for the purpose of improving the viscosity index of the base oil by hydrocracking.

[0016] <Production method of base oil> An example of a production mode of the base oil will be described below.

[0017] (1-1) Preparation of feedstock oil A Examples of the feedstock oil A include vacuum distilled oil obtained by distilling at atmospheric pressure one or more crude oils selected from paraffinic crude oil, intermediate crude oil, and naphthenic crude oil to extract fuel oil fractions such as kerosene and diesel, and then distilling at reduced pressure the atmospheric residual oil remaining at the bottom of the distillation tower, or a mixture of vacuum distilled oil and vacuum residual oil. Here, the vacuum residual oil is preferably subjected to a solvent deasphalting treatment to obtain a deasphalted oil, and then mixed with a vacuum distilled oil to be used as the feedstock oil A. That is, the feedstock oil A is preferably a mixed oil of a vacuum distilled oil and a deasphalted oil. Examples of the solvent used in the solvent deasphalting treatment include linear saturated hydrocarbons having 3 to 6 carbon atoms, specifically, propane, n-butane, isobutane, n-pentane, isopentane, n-hexane, etc. These solvents may be used alone or in combination of two or more.

[0018] (1-2) Preparation of feedstock B Examples of the feedstock B include heavy oil hydrocracking residue, and a mixture of heavy oil hydrocracking residue and wax. Heavy oil hydrocracking residual oil is a bottom fraction obtained when oil, including heavy fuel oil obtained from a vacuum distillation unit, is hydrocracked in the fuel oil production process to produce naphtha-kerosene. The wax is slack wax separated by subjecting the bottom fraction to solvent dewaxing, for example, the process described below.

[0019] (2) Refining process The feedstocks A and B are subjected to at least hydrofinishing treatment to produce mineral base oils as products. In detail, the feedstock A is preferably subjected to hydroreforming treatment, followed by at least one of solvent dewaxing treatment and hydroisomerization dewaxing treatment, and then hydrofinishing treatment. Then, as necessary, post-treatment described below is performed to produce a mineral oil base oil as a product. Note that the hydroisomerization dewaxing treatment may be performed after the hydrofinishing treatment. Therefore, the feedstock A may be subjected to hydroreforming treatment, solvent dewaxing treatment, hydrofinishing treatment, and hydroisomerization dewaxing treatment in this order, for example. When the feedstock B is a mixture of heavy oil hydrocracked residual oil and wax, it is preferably subjected to hydroisomerization dewaxing treatment, followed by hydrofinishing treatment, and then, if necessary, post-treatment described below, to produce a mineral oil base oil as a product. When the feedstock B is a residual oil obtained by hydrocracking of heavy oil, it is preferably subjected to a solvent dewaxing treatment, followed by a hydrofinishing treatment, and then, if necessary, a post-treatment described below is carried out to produce a mineral oil base oil as a product.

[0020] (Hydroreforming) Hydrotreating is a hydrorefining process carried out primarily for the purpose of improving the viscosity index of refined oil by hydrocracking. The hydroreforming treatment is carried out in the presence of a hydrorefining catalyst for hydroreforming treatment by appropriately adjusting the hydrogen partial pressure, reaction temperature, liquid hourly space velocity, and hydrogen gas supply ratio (especially the reaction temperature, liquid hourly space velocity, and hydrogen gas supply ratio), etc.

[0021] (Solvent dewaxing treatment) Solvent dewaxing is a refining process carried out for the purpose of removing wax from the feedstock oil. The solvent dewaxing treatment is carried out by appropriately adjusting various conditions.

[0022] Examples of the solvent used in the solvent dewaxing treatment include aliphatic ketones having 3 to 6 carbon atoms, such as methyl ethyl ketone and methyl isobutyl ketone; aliphatic hydrocarbons having 3 to 6 carbon atoms, such as propane and butane; toluene; and the like. The cooling temperature in the solvent dewaxing treatment is preferably -40 to 0°C, for example. The wax precipitated by cooling (slack wax) is filtered to separate it from the liquid fraction (solvent and treated oil). The solvent is then removed from the liquid fraction to obtain a solvent dewaxed oil.

[0023] (Hydroisomerization dewaxing treatment) Hydroisomerization dewaxing is a hydrorefining process that is primarily intended to isomerize linear paraffins contained in a feedstock oil into isoparaffins. The hydroisomerization dewaxing process can also remove impurities such as sulfur and nitrogen. When using feedstock A, the hydroisomerization dewaxing treatment may be performed on the wax (slack wax) separated from feedstock A by solvent dewaxing treatment, and the hydroisomerized dewaxed oil derived from the wax may be mixed with the solvent dewaxed oil. Alternatively, only the hydroisomerized dewaxed oil may be subjected to hydrofinishing treatment described later. Moreover, the hydroisomerization dewaxing treatment may be performed after the hydrofinishing treatment described later. The hydroisomerization dewaxing treatment is carried out in the presence of a hydrorefining catalyst for hydroisomerization dewaxing treatment by appropriately adjusting the hydrogen partial pressure, reaction temperature, liquid hourly space velocity, and hydrogen gas supply rate (especially the reaction temperature, liquid hourly space velocity, and hydrogen gas supply rate), etc.

[0024] (Hydrofinishing) Hydrofinishing is a hydrorefining process carried out mainly for the purpose of improving the color of refined oil, but it can also saturate aromatics contained in the feed oil and remove impurities such as sulfur and nitrogen. The hydrofinishing treatment is carried out in the presence of a hydrorefining catalyst for hydrofinishing treatment by appropriately adjusting the hydrogen partial pressure, reaction temperature, liquid hourly space velocity, and hydrogen gas supply rate (especially the reaction temperature, liquid hourly space velocity, and hydrogen gas supply rate), etc.

[0025] (Post-processing) After completion of the above-mentioned refining treatment, the resulting refined oil is subjected to vacuum distillation, and a fraction having a desired kinetic viscosity is recovered, thereby obtaining a base oil. The conditions of the reduced pressure distillation (pressure, temperature, time, etc.) are appropriately adjusted so that the kinematic viscosity of the resulting base oil falls within a desired range.

[0026] (Kinematic viscosity of base oil) The kinematic viscosity of the base oil (at 40°C) is preferably 30 mm 2 / s~500mm 2 / s, more preferably 35 mm 2 / s~470mm 2 / s, more preferably 38 mm 2 / s~450mm 2 / s. The viscosity index of the base oil is preferably 75 or more, more preferably 80 or more, and even more preferably 85 or more. In addition, it is usually 150 or less. In this specification, the kinematic viscosity and viscosity index of the base oil refer to values ​​measured or calculated in accordance with JIS K2283:2000.

[0027] (3) Hydrorefining catalyst Examples of the hydrorefining catalyst for hydroreforming, hydroisomerization dewaxing, and hydrofinishing include catalysts containing two or more metal materials selected from nickel (Ni), tungsten (W), molybdenum (Mo), and cobalt (Co); and precious metals such as platinum (Pt) and palladium (Pd). Here, the hydrorefining catalyst for hydroreforming is preferably a catalyst containing two or more metal materials selected from nickel (Ni), tungsten (W), molybdenum (Mo), and cobalt (Co), and more preferably a catalyst containing tungsten (W) and one or more metal materials selected from nickel (Ni), molybdenum (Mo), and cobalt (Co). As the hydrorefining catalyst for hydroisomerization dewaxing, a noble metal catalyst is preferred. The hydrorefining catalyst for hydrofinishing is preferably a catalyst containing two or more metal materials selected from nickel (Ni), tungsten (W), molybdenum (Mo), and cobalt (Co), and more preferably a catalyst containing one or more metal materials selected from nickel (Ni), tungsten (W), and cobalt (Co) and molybdenum (Mo). The catalyst may be used supported on a carrier, such as a composite material of silica and alumina, an amorphous carrier such as alumina, or a crystalline carrier such as zeolite.

[0028] Here, in the diagnostic method of this embodiment, the hydrorefining catalyst to be diagnosed is preferably a hydrorefining catalyst for hydrofinishing. As described above, hydrorefining is a hydrorefining process whose main purpose is to improve the color of refined oil. When the activity of the hydrorefining catalyst for hydrofinishing decreases, the color of the base oil deteriorates, and the Saybolt color becomes less than +28. When the color of the base oil deteriorates to this level, the activity of the hydrorefining catalyst has already deteriorated significantly, so that it is often difficult to recover the activity of the hydrorefining catalyst by adjusting the operating conditions. In the diagnostic method of this embodiment, the decrease in the activity of the hydrorefining catalyst for hydrofinishing can be grasped early before the color of the base oil deteriorates to this level. Therefore, the activity of the hydrorefining catalyst can be easily recovered by adjusting the operating conditions. In other words, the decrease in the activity of the hydrorefining catalyst for hydrofinishing can be grasped early, and the negative impact on base oil production can be suppressed by adjusting the operating conditions. In addition, for example, by performing an activation operation or the like, the activity of the hydrorefining catalyst for hydrofinishing can be restored, and the service life of the hydrorefining catalyst for hydrofinishing can be extended.

[0029] <Diagnostic aspects> In the diagnostic method of the present embodiment, the activity of the hydrorefining catalyst is diagnosed based on the difference between the ultraviolet-visible absorption spectrum of a base oil having a Saybolt color of +28 or more produced using the hydrorefining catalyst and the ultraviolet-visible absorption spectrum of a standard base oil having a Saybolt color of +28 or more produced using the hydrorefining catalyst. Here, the standard base oil is a diagnostic reference and is used for comparison with a base oil that is a diagnostic sample for diagnosing the activity of a hydrorefining catalyst. As the standard base oil, a base oil produced before the diagnostic sample base oil is used, and preferably a base oil produced using a hydrorefining catalyst that has not experienced a decrease in activity or has experienced only a small degree of decrease in activity (for example, a hydrorefining catalyst within a certain period of time since the start of use (preferably immediately after the start of use)). The ultraviolet-visible absorption spectrum of the diagnostic reference is then compared with the ultraviolet-visible absorption spectrum of the diagnostic sample base oil, and the activity of the hydrorefining catalyst is diagnosed based on the difference in the ultraviolet-visible absorption spectra. This makes it possible to diagnose the activity state (whether activity has decreased or is maintained) of the hydrorefining catalyst when the diagnostic sample base oil was produced, relative to the activity of the hydrorefining catalyst when the diagnostic sample base oil was produced, as compared with the activity of the hydrorefining catalyst when the diagnostic reference standard base oil was produced. In addition, when the activity of the hydrorefining catalyst is restored by, for example, activation operation, it is also possible to diagnose an improvement in the activity of the hydrorefining catalyst. Here, differences in the ultraviolet-visible absorption spectra include (1) the appearance in the ultraviolet-visible absorption spectrum of a diagnostic sample of a peak that is not present in the ultraviolet-visible absorption spectrum of the diagnostic reference; (2) for a peak detected in the ultraviolet-visible absorption spectrum of both the diagnostic reference and the diagnostic sample, an increase in the absorbance of that peak in the ultraviolet-visible absorption spectrum of the diagnostic sample; (3) for a peak detected in the ultraviolet-visible absorption spectrum of both the diagnostic reference and the diagnostic sample, a decrease in the absorbance of that peak in the ultraviolet-visible absorption spectrum of the diagnostic sample; (4) for a peak detected in the ultraviolet-visible absorption spectrum of both the diagnostic reference and the diagnostic sample, a change in the shape in the ultraviolet-visible absorption spectrum of the diagnostic sample; (5) a fluctuation in the baseline on the long wavelength side; etc.

[0030] FIG. 1 shows the ultraviolet-visible absorption spectra of the two base oils. In Figure 1, spectrum A1 is the spectrum of the base oil immediately after starting to use the hydrorefining catalyst, when the activity of the hydrorefining catalyst has not yet decreased. Spectrum A2 is the spectrum of the base oil after a certain period of time has passed since the start of using the hydrorefining catalyst. Both base oils have a Saybolt color of +30. Comparing the two spectra, spectrum A2 has many peaks that cannot be confirmed in spectrum A1, and among them, the peaks present at 430 to 440 nm are presumed to be peaks attributable to coronene dimer. It is known that the direct cause of the deterioration of the color of base oil is polycyclic aromatics, and it is believed that most of the polycyclic aromatics grow and are generated from precursors in the stripping unit and / or distillation unit in the final process of base oil production. It is presumed that after a certain period of time has passed since the start of use of the hydrorefining catalyst, the precursors increase in number and can be detected in the ultraviolet-visible absorption spectrum. In other words, changes in the ultraviolet-visible absorption spectrum observed after a certain period of time has passed since the start of use of a hydrorefining catalyst can be a sign of deterioration in the color of the base oil and can be an indicator of a decrease in the activity of the hydrorefining catalyst.

[0031] Here, in the above diagnosis (1), the activity of the hydrorefining catalyst may be judged based on the magnitude of the peak absorbance. For example, as shown in FIG. 1, the difference in absorbance (ΔAbs) between the top and bottom of a peak present at 430 to 440 nm is calculated, and when this value exceeds a certain value (i.e., a threshold is set and when this value exceeds the threshold), it is determined that the activity of the hydrorefining catalyst has decreased (hereinafter, this method is also referred to as the "first method"). The method for calculating the magnitude of the absorbance of the peak is not limited to the above-mentioned first method, and various methods capable of quantitatively determining the magnitude of the absorbance of the peak may be adopted. For example, the difference between the absorbance on the long wavelength side (e.g., a wavelength region longer than 500 nm) where no peak exists and the absorbance shows a constant value and the absorbance at the apex of the peak may be used (hereinafter, this method is also referred to as the "second method"). Alternatively, the difference or ratio between the absorbance of an intrinsic peak that does not show any fluctuation in magnitude with the use period of the hydrorefining catalyst and the absorbance of a peak that shows a fluctuation in magnitude with the use period of the hydrorefining catalyst may be used (hereinafter, this method is also referred to as the "third method").

[0032] In the above cases (2) and (3), the above first to third methods may also be employed, and the activity of the hydrorefining catalyst may be diagnosed based on a criterion of whether the magnitude of the absorbance of the peak has increased or decreased by a certain amount or more in comparison with a diagnostic reference.

[0033] The above (4) includes a case where two or more components are mixed in the peak of interest. For example, when the peak of interest is a composite peak in which a peak derived from a first component (first component peak) and a peak derived from a second component (second component peak) partially overlap, and the magnitudes of the first component peak and the second component peak vary in different ways with the duration of use of the hydrorefining catalyst, the shape of the composite peak varies with the duration of use of the hydrorefining catalyst. Therefore, for example, the activity of the hydrorefining catalyst can be diagnosed by calculating the spectral width of the composite peak and comparing it with the spectral width of the composite peak in a diagnostic reference.

[0034] The above (5) can be exemplified by the fact that the absorbance of a peak on the short wavelength side increases with the duration of use of the hydrorefining catalyst, with the effect extending to the long wavelength region, resulting in an increase in the baseline absorbance value in the long wavelength region. For example, in a diagnostic reference, no peaks are detected in the long wavelength region above a certain wavelength, which serves as the baseline, but when the absorbance of a peak on the short wavelength side increases with use of the hydrorefining catalyst, the effect can extend to the baseline region on the long wavelength side. The above (5) can diagnose the activity of the hydrorefining catalyst based on such fluctuations in the baseline absorbance.

[0035] [Base oil manufacturing method] The method for producing a base oil of this embodiment includes a step of carrying out the diagnostic method of this embodiment. Therefore, for example, after the step of implementing the diagnostic method of this embodiment, by adjusting the operating conditions of the reaction tower using the hydrotreating catalyst in accordance with the diagnostic results, it becomes possible to produce base oils having a Saybolt color of +28 or more over a long period of time.

[0036] [One aspect of the present invention provided] In one embodiment of the present invention, the following [1] to [5] are provided. [1] A method for diagnosing the activity of a hydrorefining catalyst used in the production of base oil, comprising: A diagnostic method for diagnosing activity of the hydrorefining catalyst based on the difference between the ultraviolet-visible absorption spectrum of a base oil having a Saybolt color of +28 or more produced using the hydrorefining catalyst and the ultraviolet-visible absorption spectrum of a standard base oil having a Saybolt color of +28 or more produced using the hydrorefining catalyst. [2] The kinematic viscosity of the standard base oil and the base oil at 40 ° C. is 30 mm 2 / s~500mm 2 The diagnostic method described in [1] above, wherein the patient is a schizophrenic patient. [3] The diagnostic method according to [1] or [2] above, wherein the hydrorefining catalyst is a hydrorefining catalyst for hydrofinishing. [4] The diagnostic method according to the above [3], wherein the activity of the hydrorefining catalyst is diagnosed based on at least one of an absorption peak appearing in the range of 345 to 375 nm and an absorption peak appearing in the range of 430 to 440 nm in the ultraviolet-visible absorption spectrum of the base oil. [5] A method for producing a base oil, comprising a step of carrying out the diagnostic method according to any one of the above items [1] to [4]. EXAMPLES

[0037] The present invention will be specifically described with reference to the following examples, although the present invention is not limited to the following examples. In the examples, the 40° C. kinematic viscosity and viscosity index of the base oil were measured or calculated in accordance with JIS K2283:2000. The Saybolt color was measured in accordance with JIS K2580:2003.

[0038] [Example A] Mineral base oils were produced by the method described below. Using vacuum distillation oil and solvent deasphalted oil as feedstock, a nickel-tungsten-alumina catalyst (nickel oxide and tungsten oxide supported on alumina as a carrier) was used. The reaction temperature was 360-410°C, the hydrogen partial pressure was 20MPa, and the hydrogen to feedstock supply ratio was 900Nm 3 / kL, LHSV0.9hr -1 The mixture was subjected to hydroreforming treatment under the above conditions to obtain a hydroreformed oil. The hydrogenated reformate was then subjected to a reaction using a precious metal (platinum) catalyst at a reaction temperature of 330°C, a hydrogen partial pressure of 4MPa, and a hydrogen to hydrogenated reformate feed ratio of 420Nm 3 / kL, LHSV1.1hr -1 The hydroisomerized dewaxed oil was obtained by subjecting the mixture to hydroisomerization dewaxing under the conditions of The hydroisomerized dewaxed oil was then subjected to a reaction using a nickel-molybdenum-alumina catalyst (nickel oxide and molybdenum oxide supported on an alumina carrier) at a reaction temperature of 310°C, a hydrogen partial pressure of 20 MPa, and a hydrogen to dewaxed oil feed ratio of 1,000 Nm 3 / kL, LHSV0.4hr -1The mixture was subjected to hydrofinishing treatment under the conditions of 100° C. Then, the target fraction was recovered by vacuum distillation to obtain a mineral oil base oil. Under the above conditions, production of 500 kL (kiloliters) of mineral base oil was continued per day. Then, the UV-visible absorption spectra of the base oils produced 30, 200, 400, and 600 days after the start of use of the hydrofinishing hydrogenation catalyst were measured using a UV-visible spectrophotometer (Shimadzu Corporation, UV-2700).

[0039] The results are shown in Figure 2. The base oils had a Saybolt color of +30 after 30, 200, 400, and 600 days from the start of use of the hydrofinishing hydrogenation catalyst. In addition, the kinetic viscosity of mineral base oils at 40°C is 80mm 2 / s~100mm 2 The viscosity index of the mineral base oils was in the range of 100 to 120.

[0040] From the results shown in Figure 2, the mineral oil base oil produced 30 days after the start of use of the hydrofinishing catalyst did not show any absorption peak at 430 to 440 nm. It is believed that this result was obtained because the activity of the hydrorefining catalyst for hydrofinishing did not decrease at all 30 days after the start of use of the hydrofinishing catalyst for hydrofinishing. Next, the mineral oil base oils produced 200, 400, and 600 days after the start of use of the hydrofinishing hydrogenation catalyst showed peaks at 430 to 440 nm, and the intensity of the peaks tended to increase as the number of days since the start of use of the hydrofinishing hydrogenation catalyst increased. These results demonstrate that even for base oils with a Saybolt color of +30, it is possible to grasp and diagnose the decrease in activity of the hydrorefining catalyst for hydrofinishing by checking the ultraviolet absorption spectrum.

[0041] [Example B] Mineral base oils were produced by the method described below. The heavy oil hydrocracking residue and wax were used as the feedstock (corresponding to the mixed oil of feedstock B above). The conditions for hydrocracking heavy fuel oil to obtain residual oil from hydrocracking of heavy oil are as follows: reaction temperature 390°C, pressure 15MPa, H2 / oil=400Nm3 in the presence of an iron zeolite catalyst. 3 / kL, LHSV2.2hr -1 It was decided. First, a precious metal (platinum) catalyst was used for the feedstock oil, and the reaction temperature was 330°C, the hydrogen partial pressure was 4MPa, and the hydrogen to hydrogenated reformate feed ratio was 420Nm 3 / kL, LHSV1.1hr -1 The hydroisomerized dewaxed oil was obtained by subjecting the mixture to hydroisomerization dewaxing under the conditions of The hydroisomerized dewaxed oil was then subjected to a reaction using a nickel-molybdenum-alumina catalyst (nickel oxide and molybdenum oxide supported on an alumina carrier) at a reaction temperature of 310°C, a hydrogen partial pressure of 20 MPa, and a hydrogen to dewaxed oil feed ratio of 1,000 Nm 3 / kL,LHSV0.4hr -1 The mixture was subjected to hydrofinishing treatment under the conditions of 100° C. Then, the target fraction was recovered by vacuum distillation to obtain a mineral oil base oil. Under the above conditions, production of 500 kL of mineral base oil per day was continued. Then, the UV-visible absorption spectra of the base oils produced 200 and 300 days after the start of use of the hydrofinishing hydrogenation catalyst were measured using a UV-visible spectrophotometer (Shimadzu Corporation, UV-2700).

[0042] The results are shown in Figure 3. The base oils 200 and 300 days after the start of use of the hydrofinishing catalyst had a Saybolt color of +30. In addition, the kinetic viscosity of mineral base oils at 40°C is 30mm 2 / s~70mm 2 The viscosity index of the mineral base oils was in the range of 110 to 140.

[0043] From the results shown in Figure 3, the mineral oil base oil produced 200 days after the start of use of the hydrofinishing catalyst only showed a very gentle peak at 345 to 375 nm. It is believed that this result was obtained because the degree of decrease in activity of the hydrorefining catalyst for hydrofinishing was small 200 days after the start of use of the hydrofinishing catalyst. Next, the mineral oil base oil produced 300 days after the start of use of the hydrofinishing catalyst showed a shoulder-shaped absorption peak at 345 to 375 nm that was clearly more pronounced than the mineral oil base oil produced after 200 days. These results demonstrate that even for base oils with a Saybolt color of +30, it is possible to grasp and diagnose the decrease in activity of the hydrorefining catalyst for hydrofinishing by checking the ultraviolet absorption spectrum.

[0044] [Example C] Mineral base oils were produced by the method described below. Heavy oil hydrocracking residue was used as the feedstock (corresponding to the heavy oil hydrocracking residue of feedstock B above). The conditions for hydrocracking heavy fuel oil to obtain residual oil from hydrocracking of heavy oil are as follows: reaction temperature 390°C, pressure 15MPa, H2 / oil=400Nm3 in the presence of an iron zeolite catalyst. 3 / kL, LHSV2.2hr -1 It was decided. First, toluene and methyl ethyl ketone were mixed with the feed oil and cooled to below -20°C. The precipitated wax was removed, and then the toluene and methyl ethyl ketone were removed to obtain a solvent dewaxed oil. The solvent dewaxed oil was then subjected to a reaction using a nickel-molybdenum-alumina catalyst (nickel oxide and molybdenum oxide supported on an alumina carrier) at a reaction temperature of 310°C, a hydrogen partial pressure of 20 MPa, and a hydrogen to dewaxed oil feed ratio of 1,000 Nm 3 / kL,LHSV0.4hr -1 The mixture was subjected to hydrofinishing treatment under the conditions of 100° C. Then, the target fraction was recovered by vacuum distillation to obtain a mineral oil base oil. Under the above conditions, production of 500 kL of mineral base oil per day was continued. Then, the UV-visible absorption spectra of the base oils produced 200 and 300 days after the start of use of the hydrofinishing hydrogenation catalyst were measured using a UV-visible spectrophotometer (Shimadzu Corporation, UV-2700).

[0045] The results are shown in Figure 4. The base oils 200 and 300 days after the start of use of the hydrofinishing catalyst had a Saybolt color of +30. In addition, the kinetic viscosity of mineral base oils at 40°C is 30mm 2 / s~70mm 2 The viscosity index of the mineral base oils was in the range of 110 to 140.

[0046] From the results shown in Figure 4, a shoulder-shaped peak was confirmed at 345 to 375 nm for both the mineral oil base oil produced 200 days after the start of use of the hydrofinishing catalyst and the mineral oil base oil produced 300 days after the start of use, but the magnitude of the shoulder-shaped peak was slightly larger for the mineral oil base oil produced 300 days after the start of use of the hydrofinishing catalyst. From the above, it is considered that the degree of decrease in the activity of the hydrofinishing catalyst for hydrofinishing is greater for the mineral oil base oil produced 300 days after the start of use of the hydrofinishing catalyst than for the mineral oil base oil produced 200 days after the start of use of the hydrofinishing catalyst, and this result was obtained. These results demonstrate that even for base oils with a Saybolt color of +30, it is possible to grasp and diagnose the decrease in activity of the hydrorefining catalyst for hydrofinishing by checking the ultraviolet absorption spectrum.

Claims

1. A method for diagnosing the activity of a hydrorefining catalyst used in the production of base oil, comprising: A diagnostic method for diagnosing the activity of the hydrorefining catalyst based on the difference between the ultraviolet-visible absorption spectrum of a base oil produced using the hydrorefining catalyst and having a Saybolt color of +28 or more, and the ultraviolet-visible absorption spectrum of a standard base oil produced using the hydrorefining catalyst and having a Saybolt color of +28 or more.

2. The kinematic viscosity of the standard base oil and the base oil at 40 ° C. is 30 mm ２ / s ~ 500 mm ２ The diagnostic method according to claim 1, wherein the α-amino acid sequence is / s.

3. The diagnostic method according to claim 1 or 2, wherein the hydrorefining catalyst is a hydrorefining catalyst for hydrofinishing.

4. 4. The diagnostic method according to claim 3, wherein the activity of the hydrorefining catalyst is diagnosed based on at least one of an absorption peak appearing in the range of 345 to 375 nm and an absorption peak appearing in the range of 430 to 440 nm in the ultraviolet-visible absorption spectrum of the base oil.

5. A method for producing a base oil, comprising a step of carrying out the diagnostic method according to claim 1 or 2.

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