JP4580539B2 - Method for predicting decrease in activity of hydrodesulfurization catalyst and method for operating hydrodesulfurization apparatus using the same - Google Patents

Description

と直線関係になることから、反応次数は１．５次であり、下記式（ａ）で表現される。
【数７】

（ｋ：反応速度定数、Ｓ_Ｐ、Ｓ_Ｆ、ＬＨＳＶは前記と同一。）
そこで、強制劣化前の活性評価試験[条件：原料ＬＧＯ 温度３２０℃、３４０℃、３６０℃ ＬＨＳＶ＝１ｈ^−１ 反応圧力５．８８ＭＰａ]で得られた生成油中の硫黄濃度より各温度の反応速度定数ｋおよび生成油中の硫黄濃度が５０ｐｐｍとなる反応速度定数ｋ_０を式（ａ）より求める。
各温度の絶対温度の逆数（１／Ｔ）と対応するｌｎｋの関係を図１に示すようにプロットし、最小二乗法により近似したｌｎｋ＝Ａ（１／Ｔ）＋Ｂの式に、生成油中の硫黄濃度が５０ｐｐｍになるｌｎｋ_０を代入し、温度（Ｔ_０）を求める。一方、強制劣化後の活性評価試験[条件：原料ＬＧＯ 温度３２０℃、３４０℃、３６０℃ ＬＨＳＶ＝１ｈ^−１ 反応圧力５．８８ＭＰａ]より得られた各温度での生成油中の硫黄濃度から、式（ａ）を用いて各温度での反応速度定数ｋを求める。
活性劣化後の各温度の絶対温度の逆数（１／Ｔ）とｌｎｋとの関係を近似したｌｎｋ＝Ａ（１／Ｔ）＋Ｂに、強制劣化前の活性試験で求めた生成油中の硫黄濃度が５０ｐｐｍとした温度（Ｔ_０）を代入し、ｌｎｋ_ｔを求める。
つぎに
（劣化後の活性試験により求めたｌｎｋ_ｔ）−（劣化前の活性試験より求めたｌｎｋ_０）よりｌｎ（ｋ_ｔ／ｋ_０）
を求め、各原料が触媒の活性低下に与える影響を定量化する。各原料組成が触媒への活性低下に与える影響を定量化した値ｌｎ（ｋ_ｔ／ｋ_０）と各原料組成を統計的手法の１つである多重回帰により活性低下予測式の劣化定数（α_ｎ）を算出した。
【００１３】
触媒の劣化程度はｌｎ（ｋ_ｔ／ｋ_０）はｔ時間経過後の反応速度定数ｋ_ｔの初期反応速度定数ｋ_０に対する割合であることから、アレニウスの式によって反応温度の関数に変換でき下式になる。
【数８】
ｋ_ｔ／ｋ_０＝ｅｘｐ｛Ｅ／Ｒ〔（１／Ｔ_ｔ）−（１／Ｔ_０）〕｝
そのため触媒の活性低下を補償するための要求温度Ｔ_ｔ（ｔ時間後に初期生成物硫黄濃度と同等にするための温度）は、活性劣化式を上式に代入して、下記式により求めることができる。
【数９】

（Ｒ：気体定数、Ｅ：活性化エネルギー、Ｔ_０：初期反応温度、ｌｎｋ_ｔ／ｋ_０：触媒の劣化程度）
上の式を用いて原料組成から求めた劣化定数−（α_１ｘ_１＋α_２ｘ_２＋〜＋α_ｎｘ_ｎ）と運転期間（ｔ）を一年後、二年後と設定して、要求温度を算出する。
この予測した要求温度により運転方法が決められる。装置上限温度、例えば３８０℃と比較して、運転期間、触媒再生時期が設定されたり、反対に、装置上限温度を設定し、運転期間や、劣化定数すなわち原料組成を決定することもできる。
【００１４】
本発明における原料油の組成については、単環芳香族、ナフタレン環芳香族、ナフタレン環以外の二環芳香族、三環芳香族、四環以上の芳香族化合物、の各成分濃度は高速液体クロマトグラフィー、ガスクロマトグラフィー、紫外分光高度法などにより濃度を算出し、難脱硫性硫黄化合物、難脱硫性硫黄化合物以外の硫黄化合物は、原子吸光検出器を備えたガスクロマトグラフィー、液体クロマトグラフィーなどにより濃度を算出し窒素化合物はミクロケルダール法、微量電量滴定、化学発光法により算出する。
【００１５】
【実施例】
以下に実施例を挙げて本発明を説明するが、本発明はこれにより何等限定されるものではない。
【００１６】
実施例１
以下に活性低下予測式の算出およびその式を用いた実施例を示す。
ＬＣＯ（分解軽油）を蒸留分離し、単環、２環、３環以上の芳香族化合物が濃縮された留分を直留軽油（ＬＧＯ）に混合し、原料中の単環、２環、３環以上の芳香族化合物濃度が異なる原料を各試験（試験Ｎｏ．１９Ｂ〜２２Ｂ）にかけるよう調製した。各試験に用いた原料の組成を表１に示す。各原料について高圧流通式反応装置（触媒充填量２０ｃｃ）にて活性評価［条件：原料ＬＧＯ 温度３２０℃、３４０℃、３６０℃ ＬＨＳＶ＝１ｈ^−１ 反応圧力５．８８ＭＰａ］、強制劣化［温度３８０℃ ＬＨＳＶ＝１ｈ^−１ 反応圧力１．９６ＭＰａ 反応時間＝２１６ｈ］、活性評価［条件：原料ＬＧＯ 温度３２０℃、３４０℃、３６０℃ ＬＨＳＶ＝１ｈ^−１ 反応圧力５．８８ＭＰａ］を行い、活性評価での各温度の生成油中の硫黄濃度より反応速度定数の比ｌｎ（ｋ_ｔ／ｋ_０）及び強制劣化時間２１６ｈで割ったｌｎ（ｋ_ｔ／ｋ_０）／ｔを求めた。各原料の組成および各原料に対応した劣化程度ｌｎ（ｋ_ｔ／ｋ_０）、時間あたりの劣化程度ｌｎ（ｋ_ｔ／ｋ_０）／ｔを表１に示す。
【表１】

【００１７】
上記表１の各化合物グループ濃度と劣化前後の反応速度係数の比を反応時間で割った値ｌｎ（ｋ_ｔ／ｋ_０）／ｔを多重回帰し、各化合物グループの劣化定数を求め、下記活性劣化式（ｂ）を導出した。
【数１０】

この場合、１．４６×１０^−５は、単環化合物の劣化定数α_１であり、１．３３×１０^−４は２環化合物の劣化定数α_２であり、１．１１×１０^−４は３環以上の芳香族化合物の劣化定数α_３である。
【００１８】
実施例２
前記表１は、請求項１発明の実施結果の１例であるが、１９Ｂ、１９Ｆ、２０Ａ、１９Ｃ、２０Ｃ、２２Ｂの原料組成を単環化合物、２環、ナフタレン以外の２環（２．５環）、３環化合物、４環以上化合物のグループに分け、各原料中の各化合物グループ濃度を測定した。結果を下記表２に示す。
【表２】

【００１９】
上記表２の各化合物グループ濃度と劣化前後の反応速度係数の比を反応時間で割った値ｌｎ（ｋ_ｔ／ｋ_０）／ｔを多重回帰し、各化合物グループの劣化定数を求め、活性劣化式（ｃ）を導出した。
【数１１】

この場合、３．４０×１０^−５は、単環化合物の劣化定数α_１、７．９８×１０^−５は２環化合物の劣化定数α_２、２．５７×１０^−４は２．５環化合物の劣化定数α_３、２．１１×１０^−４は３環化合物の劣化定数α_４、１．０９×１０^−５は４環以上の芳香族化合物の劣化定数α_５を示す。
【００２０】
表１、表２における試験１９Ｂの原料組成と同じ原料を用いて反応圧力：１．９６ＭＰａ、ＬＨＳＶ：１ｈ^−１の条件で運転した場合の要求温度Ｔを予測する。

以上の値を〔数８〕に代入すると要求温度Ｔ_ｔは、
【数１２】

１９Ｂの原料を水素化脱硫反応させ、生成油中の硫黄濃度を５０ｐｐｍまで脱硫する場合、２１６時間には、反応温度が３４２．７１９６℃から３５８．６６℃に上昇すると予測できる。
【００２１】
【発明の効果】
（１）本発明により、かなり精度の高い水素化脱硫触媒の活性低下を予測することができる。
（２）本発明により、水素化脱硫装置における水素化脱硫触媒が、時間の経過と共にどのように劣化してゆくかを予測し、そのデータを基にその触媒を用いた水素化脱硫装置の運転スケジュールを立案することができる。
【図面の簡単な説明】
【図１】活性評価で得られた生成油中の硫黄濃度から活性劣化の程度を表わすｌｎ（ｋ_ｔ／ｋ_０）を求める方法を表わした図である。
【図２】各化合物（コーク生成原因物質グループ）の脱硫触媒の活性劣化に与える影響を調べるため、すなわち、請求項１の各化合物（コーク生成原因物質グループ）の劣化定数を求めるための活性評価、強制劣化方法およびそれらの条件を示す図である。[0001]
BACKGROUND OF THE INVENTION
When producing light oil of low sulfur content from petroleum distillate feedstock, use the method of predicting the hydrodesulfurization reaction activity of the compound used as a catalyst without actually performing the hydrodesulfurization reaction and use the obtained prediction method The present invention relates to a method for operating a conventional hydrodesulfurization apparatus.
[0002]
[Prior art]
Coke deposition on the catalyst is the main cause of decreased activity in the hydrodesulfurization reaction of diesel oil fractions, but in order to increase diesel oil production, a high mixture of cracked oil and residual oil, which are thought to contain a large amount of coke-causing substances, is used. Must be mixed in proportions. However, it has not been clarified which type of substance in cracked oil or residual oil greatly contributes to a decrease in the activity of the catalyst.
[0003]
A number of methods for predicting the decrease in activity and the decrease in activity of hydrodesulfurization catalysts have been proposed. For example, Idei et al. In Chemical Engineering Papers, 24, 4 (1998) and Chemical Engineering Papers, 21, 6 (1995), propose a hydrodesulfurization catalyst activity reduction rate formula and activity reduction prediction formula.
[0004]
However, in these documents, as described above, the idea is to deal with the superordinate concepts of light oil (LGO) and vacuum gas oil (VGO), and the idea of predicting the hydrodesulfurization activity decrease due to the influence of the composition of the feedstock is completely Not disclosed.
[0005]
On the other hand, as a response to the increase in demand for light oil, there is an increasing need to mix cracked light oil (LCO) into the light oil fraction because only the usual light oil fraction becomes a raw material shortage. It contains a large amount of polycyclic aromatic compounds, sulfur compounds, nitrogen compounds and the like that are considered to be the causative substances of formation. For this reason, there is a concern that the catalyst activity will decrease more quickly, and the current situation is that the mixing ratio cannot be made higher than the actual operation results of the actual apparatus. In order to plan the mixing process in accordance with the operation period, an activity decrease prediction method that can cope with changes in the mixing ratio and feedstock type is desired.
[0006]
[Problems to be solved by the invention]
The object of the present invention is not the coke generation causative substance contained in cracked light oil or residue oil as a raw material oil, but a lower concept such as cracked light oil, for example, a bicyclic aromatic group, a tricyclic aromatic group It can be divided into aromatic groups with four or more rings, non-desulfurizable sulfur compound groups, sulfur compounds other than non-desulfurizable sulfur compounds, nitrogen compounds, etc., and the activity that can estimate the reaction temperature after a certain period from each group concentration The purpose is to derive a decrease prediction formula, predict the decrease in activity using the obtained activity decrease prediction formula, and elucidate a prediction method and an operation method useful for planning the operation period, the mixing ratio of cracked oil and residual oil.
[0007]
[Means for Solving the Problems]
The first of the present invention is the following formula (1) from the concentration of each coke-causing substance group in the feedstock and the reaction time.
[Equation 3]
ln (k _t / k ₀ ) = − (α ₁ x ₁ + α ₂ x ₂ +... + α _n x _n ) t (1)
(Where k _t is the hydrodesulfurization reaction rate constant after t hours, k ₀ is the initial hydrodesulfurization reaction rate constant, α _{1 to} α _n are the respective degradation constants of each coke generation causative substance group, x ₁ ~x _n each concentration of each coke causative agent group in the raw material oil, t is the reaction time.)
It is related with the method of estimating the activity fall of a hydrodesulfurization catalyst using the activity fall prediction formula shown by these.
[0008]
The second of the present invention is the following formula (2) from the concentration of each coke-causing substance group in the feedstock, the reaction time, the hydrogen partial pressure, and the feedstock residence time.
[Equation 4]
ln (k _t / k ₀ ) = − (α ₁ x ₁ + α ₂ x ₂ +... + α _n x _n ) ×
(P / P ₀ ) ^β γ (LHSV / LHSV ₀ ) t (2)
(Where k _t is the hydrodesulfurization reaction rate constant after t hours, k ₀ is the initial hydrodesulfurization reaction rate constant, α _{1 to} α _n are the respective degradation constants of each coke generation cause substance group, x ₁ ~x _n each concentration of each coke causative agent group in the raw material oil, t is the reaction time, P is the hydrogen partial pressure, P ₀ is the correction coefficient of a reference partial hydrogen pressure, beta hydrogen partial pressure, gamma is The liquid space velocity correction coefficient, LHSV is the liquid space velocity, and LHSV ₀ is the reference liquid space velocity.)
It is related with the method of estimating the activity fall of a hydrodesulfurization catalyst using the activity fall prediction formula shown by these.
[0009]
According to a third aspect of the present invention, there is provided a hydrodesulfurization apparatus characterized by adjusting an operation period and a feed oil composition of the hydrodesulfurization apparatus based on a degree of decrease in catalytic activity predicted by the method according to claim 1 or 2. It relates to the driving method.
[0010]
Each coefficient is prepared by variously adjusting raw materials having different concentrations of each causative substance group, forcibly degrading the catalyst using a high-pressure flow reactor, and the degree of decrease in activity is a hydrodesulfurization reaction rate constant before and after degradation (hereinafter referred to as “degradation rate constant” ) The reaction rate constant) . It is calculated using a statistical method from the ratio of the reaction rate constant and the concentration of the causative substance.
[0011]
In order to quantify the effect of coke formation-causing substances in the mixed gas oil on the catalyst activity reduction, forced degradation and activity evaluation of the desulfurization catalyst were performed using a high-pressure flow reactor. The forced deterioration conditions were a reaction temperature of 380 ° C., a pressure of 1.96 MPa, and LHSV1h ⁻¹ . The activity was evaluated before and after forced deterioration using light oil as a raw material, and as shown in FIG. 1, an Arrhenius plot of the reaction rate constant against temperature was obtained according to the sulfur concentration of the product oil at a certain reaction temperature. From FIG. 1, the reaction rate constant (lnk ₀ ) at which the sulfur concentration in the product oil becomes 50 ppm is obtained, and the reaction rate constant (lnk _t ) at the temperature reached 50 ppm before forced deterioration is obtained from the Arrhenius plot after forced deterioration. It was. After the degree of activity decrease was specific ln _(k t / k ₀₎ as a numerical value of the rate constant _{(quantification), ln (k t / k} 0) and the coke causative agent from the raw material composition used in the accelerated aging The degradation constant based on the group concentration was calculated by a statistical method.
[0012]
Research on the reaction rate has been conducted for a long time, and the hydrodesulfurization reaction of pure sulfur compounds is a primary reaction (theoretical reaction) based on the results of many studies. However, petroleum distillates containing various sulfur compounds with different reactivities. reaction order in partial hydrodesulfurization reaction is known to be apparently n-order reaction, the reaction rate constant k _n is the reaction order n, product sulfur concentration S _P, feedstock sulfur concentration S _F, a liquid hourly space It is expressed by the following equation as a function of the speed LHSV.
[Equation 5]
k _n = (1 / n−1) [(1 / _SP ⁿ⁻¹ ) − (1 / S _F ⁿ⁻¹ )] LHSV
In general, the reaction order varies depending on the fraction.

Therefore, the reaction order is 1.5 and is expressed by the following formula (a).
[Expression 7]

(K: Reaction rate constant, S _P , S _F , LHSV are the same as above.)
Therefore, the reaction rate at each temperature from the sulfur concentration in the product oil obtained in the activity evaluation test before forced deterioration [conditions: raw material LGO temperature 320 ° C., 340 ° C., 360 ° C. LHSV = 1 h ⁻¹ reaction pressure 5.88 MPa]. The reaction rate constant k _{0 at} which the constant k and the sulfur concentration in the product oil are 50 ppm is determined from the equation (a).
The relationship between the reciprocal (1 / T) of the absolute temperature of each temperature and the corresponding lnk is plotted as shown in FIG. 1, and the equation of lnk = A (1 / T) + B approximated by the least square method is added to the generated oil. Substituting lnk _{0 at} which the sulfur concentration of the water becomes 50 ppm, the temperature (T ₀ ) is obtained. On the other hand, from the sulfur concentration in the product oil at each temperature obtained from the activity evaluation test after forced deterioration [conditions: raw material LGO temperature 320 ° C., 340 ° C., 360 ° C. LHSV = 1h ⁻¹ reaction pressure 5.88 MPa] The reaction rate constant k at each temperature is determined using equation (a).
The sulfur concentration in the product oil determined by the activity test before forced degradation to lnk = A (1 / T) + B, which approximates the relationship between the inverse of absolute temperature (1 / T) of each temperature after activation degradation and lnk Is substituted with the temperature (T ₀ ) at which 50 ppm is determined, and lnk _t is obtained.
Next, ln (k _t / k ₀ ) from (Ink _t determined by the activity test after deterioration) − (Ink ₀ determined from the activity test before deterioration)
And the effect of each raw material on the decrease in the activity of the catalyst is quantified. A value ln (k _t / k ₀ ) obtained by quantifying the influence of each raw material composition on the catalyst activity decrease, and the deterioration constant (α) of each raw material composition by multiple regression which is one of statistical methods. _n ) was calculated.
[0013]
The deterioration degree of the catalyst is ln (k _t / k ₀ ), which is the ratio of the reaction rate constant k _t after the elapse of time _{t to} the initial reaction rate constant k ₀ , and can be converted into a function of the reaction temperature by the Arrhenius equation. It becomes an expression.
[Equation 8]
k _t / k ₀ = exp {E / R [(1 / T _t ) − (1 / T ₀ )]}
Therefore, the required temperature T _t (temperature for equalizing the initial product sulfur concentration after time _t) to compensate for the decrease in the activity of the catalyst can be obtained by the following equation by substituting the activity deterioration equation into the above equation. it can.
[Equation 9]

(R: gas constant, E: activation energy, T ₀ : initial reaction temperature, lnk _t / k ₀ : degree of catalyst degradation)
Deterioration constants-(α ₁ x ₁ + α ₂ x ₂ + to + α _n x _n ) and operation period (t) determined from the raw material composition using the above formula are set as one year and two years later, and requested. Calculate the temperature.
The operation method is determined by the predicted required temperature. Compared to the upper limit temperature of the apparatus, for example, 380 ° C., the operation period and the catalyst regeneration timing can be set, and conversely, the upper limit temperature of the apparatus can be set to determine the operation period and the deterioration constant, that is, the raw material composition.
[0014]
Regarding the composition of the raw material oil in the present invention, the concentration of each component of monocyclic aromatic, naphthalene ring aromatic, bicyclic aromatic other than naphthalene ring, tricyclic aromatic, and tetracyclic or higher aromatic compounds is high performance liquid chromatography. Concentration is calculated by chromatography, gas chromatography, ultraviolet spectroscopic altitude method, etc., and sulfur compounds other than non-desulfurizable sulfur compounds and non-desulfurizable sulfur compounds are obtained by gas chromatography equipped with atomic absorption detector, liquid chromatography, etc. The concentration is calculated and the nitrogen compound is calculated by the micro Kjeldahl method, microcoulometric titration, or chemiluminescence method.
[0015]
【Example】
Hereinafter, the present invention will be described with reference to examples, but the present invention is not limited thereto.
[0016]
Example 1
The calculation of the activity decrease prediction formula and examples using the formula are shown below.
LCO (decomposed light oil) is separated by distillation, and a fraction enriched with monocyclic, bicyclic, tricyclic or more aromatic compounds is mixed with straight-run gas oil (LGO), and the monocyclic, bicyclic, tricyclic, It prepared so that the raw material from which the aromatic compound density | concentration of a ring or more differs could be applied to each test (test No. 19B-22B). Table 1 shows the composition of the raw materials used in each test. Activity evaluation for each raw material in a high-pressure flow reactor (catalyst filling amount: 20 cc) [Conditions: Raw material LGO temperature 320 ° C., 340 ° C., 360 ° C. LHSV = 1h ⁻¹ reaction pressure 5.88 MPa], forced deterioration [temperature 380 ° C. LHSV = 1h ⁻¹ reaction pressure 1.96 MPa reaction time = 216 h], activity evaluation [conditions: raw material LGO temperature 320 ° C., 340 ° C., 360 ° C. LHSV = 1 h ⁻¹ reaction pressure 5.88 MPa] The ratio of reaction rate constants ln (k _t / k ₀ ) and ln (k _t / k ₀ ) / t divided by the forced deterioration time 216 h were determined from the sulfur concentration in the product oil at each temperature. Table 1 shows the composition of each raw material, the degree of deterioration ln (k _t / k ₀ ) corresponding to each raw material, and the degree of deterioration ln (k _t / k ₀ ) / t per time.
[Table 1]

[0017]
Multiple regression of the value ln (k _t / k ₀ ) / t obtained by dividing the ratio of each compound group concentration in Table 1 above and the reaction rate coefficient before and after degradation by the reaction time to obtain the degradation constant of each compound group The deterioration formula (b) was derived.
[Expression 10]

In this case, 1.46 × 10 ⁻⁵ is the degradation constant α ₁ of the monocyclic compound, 1.33 × 10 ⁻⁴ is the degradation constant α ₂ of the bicyclic compound, and 1.11 × 10 ⁻⁴ is It is a deterioration constant α ₃ of an aromatic compound having three or more rings.
[0018]
Example 2
Table 1 is an example of the results of the invention of claim 1, and the raw material composition of 19B, 19F, 20A, 19C, 20C, and 22B is changed to a monocyclic compound, two rings, and two rings other than naphthalene (2.5 Ring), tricyclic compounds, and groups of 4 or more rings were divided into groups, and the concentration of each compound group in each raw material was measured. The results are shown in Table 2 below.
[Table 2]

[0019]
The value ln (k _t / k ₀ ) / t obtained by dividing the concentration of each compound group in Table 2 above and the reaction rate coefficient before and after degradation by the reaction time is subjected to multiple regression to determine the degradation constant of each compound group, and the activity degradation Formula (c) was derived.
[Expression 11]

In this case, 3.40 × 10 ⁻⁵ is a degradation constant α ₁ of a monocyclic compound, 7.98 × 10 ⁻⁵ is a degradation constant α ₂ of a bicyclic compound, and 2.57 × 10 ⁻⁴ is 2.5 rings. The degradation constants α ₃ and 2.11 × 10 ⁻⁴ of the compound are degradation constants α ₄ and 1.09 × 10 ⁻⁵ of the tricyclic compound, and the degradation constant α ₅ of the aromatic compound having 4 or more rings.
[0020]
The required temperature T when operating under the conditions of reaction pressure: 1.96 MPa and LHSV: 1h ⁻¹ using the same raw material as the raw material composition of Test 19B in Tables 1 and 2 is predicted.

When the above value is substituted into [Equation 8], the required temperature T _t is
[Expression 12]

When the raw material 19B is hydrodesulfurized and the sulfur concentration in the product oil is desulfurized to 50 ppm, the reaction temperature can be predicted to increase from 342.7196 ° C. to 358.66 ° C. in 216 hours.
[0021]
【The invention's effect】
(1) According to the present invention, it is possible to predict a decrease in the activity of the hydrodesulfurization catalyst with considerably high accuracy.
(2) According to the present invention, it is predicted how the hydrodesulfurization catalyst in the hydrodesulfurization apparatus will deteriorate with the passage of time, and the operation of the hydrodesulfurization apparatus using the catalyst is based on the data. You can make a schedule.
[Brief description of the drawings]
FIG. 1 is a diagram showing a method for obtaining ln (k _t / k ₀ ) representing the degree of activity deterioration from the sulfur concentration in a product oil obtained by activity evaluation.
FIG. 2 is an activity evaluation for examining the influence of each compound (coke generation cause substance group) on the activity deterioration of the desulfurization catalyst, that is, for determining the deterioration constant of each compound (coke formation cause substance group) according to claim 1; It is a figure which shows the forced degradation method and those conditions.

Claims (3)

From the concentration of each coke-causing substance group in the feedstock and the reaction time, the following formula (1)
[Equation 1]
ln (k _t / k ₀ ) = − (α ₁ x ₁ + α ₂ x ₂ +... + α _n x _n ) t (1)
(Where k _t is the hydrodesulfurization reaction rate constant after t hours, k ₀ is the initial hydrodesulfurization reaction rate constant, α _{1 to} α _n are the respective degradation constants of each coke generation causative substance group, x ₁ ~x _n each concentration of each coke causative agent group in the raw material oil, t is the reaction time.)
The method of predicting the activity fall of a hydrodesulfurization catalyst using the activity fall prediction formula shown by these. From the concentration of each coke-causing substance group in the feedstock, reaction time, hydrogen partial pressure, and feedstock residence time, the following formula (2)
[Equation 2]
ln (k _t / k ₀ ) = − (α ₁ x ₁ + α ₂ x ₂ +... + α _n x _n ) ×
(P / P ₀ ) ^β γ (LHSV / LHSV ₀ ) t (2)
(Where k _t is the hydrodesulfurization reaction rate constant after t hours, k ₀ is the initial hydrodesulfurization reaction rate constant, α _{1 to} α _n are the respective degradation constants of each coke generation cause substance group, x ₁ ~x _n each concentration of each coke causative agent group in the raw material oil, t is the reaction time, P is the hydrogen partial pressure, P ₀ is the correction coefficient of a reference partial hydrogen pressure, beta hydrogen partial pressure, gamma is The liquid space velocity correction coefficient, LHSV is the liquid space velocity, and LHSV ₀ is the reference liquid space velocity.)
The method of predicting the activity fall of a hydrodesulfurization catalyst using the activity fall prediction formula shown by these.   A hydrodesulfurization apparatus operating method, comprising adjusting the operation period and feedstock composition of the hydrodesulfurization apparatus based on the degree of decrease in catalyst activity predicted by the method according to claim 1 or 2.

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