In-situ washing procedure to recover the catalytic activity of a deactivated hydrodesulfurization catalyst

Abstract

The present invention is an in-situ cleaning procedure for the recovery of catalytic activity of a based alumina HDS catalyst, molybdenum, nickel coated coke and contaminants and it has an HDS activity seriously diminished. The catalyst under study had between 13 and 18 wt % total carbon. Reformate, half the total volume, industrial toluene=35 volume % and Iso-propylic alcohol, 15 volume %, in order to reactivate a deactivated catalyst, a solvent mixture with the following volumetric ratio is prepared. Or it can also be used only reformate (100% volume). The solvent mixture is passed using a LHSV of 2 hr1 for 72 hours at 50 C. or also using a recirculating three 24-hour cycles at 50 C. Option lasts 24 hours pure reformate LHSV=2h1 to 50 C. The washed catalyst is fed back to the load reaction conditions maintained for 36 hours at 340 C., to initiate HDS activity balances. During this treatment oxides of molybdenum and nickel in the active phase are re-sulfided by increasing the HDS activity. The In-Situ Cleaning procedure to reactivate deactivated hydrotreating catalysts used to partially remove the carbon and increase the active phase of molybdenum di-sulphide, and also retrieve specific area, and hydrogenation sites that promote higher hydrodesulfurization activity of gasoil after this treatment.

Claims

1. A procedure for removing coke from a deactivated hydrodesulfurization catalyst and recovering online hydrodesulfurization activity of the deactivated hydrodesulfurization catalyst, the procedure comprising the steps of: a) Introducing a flow of solvent containing industrial naphtha reformate within a bed of the deactivated hydrodesulfurization catalyst; b) Increasing the temperature to the range of 30 to 70 C.; c) Introducing a flow of inert gas into the bed of the deactivated hydrodesulfurization catalyst, wherein the inert gas is nitrogen, argon, or helium; and d) Increasing the pressure of the inert gas to the range of 30 to 80 Kg/cm.sup.2, to thereby remove coke from the hydrodesulfurization catalyst, whereby the online hydrodesulfurization activity of the catalyst after the procedure is higher than the online hydrodesulfurization activity of the catalyst before the procedure.

2. The procedure according to claim 1, wherein the naphtha reformate is a refinery stream having an initial boiling temperature of 120 C. and a final boiling temperature of 230 C.

3. The procedure according to claim 1, wherein the naphtha reformate comprises a mixture of hydrocarbons, paraffinic, iso-paraffinic, olefinic, naphthenic and aromatic, from 5 to 12 carbon atoms.

4. The procedure according to claim 1, wherein the industrial naphtha reformate is a single solvent used in step a).

5. The procedure according to claim 1, wherein the industrial naphtha reformate is diluted with toluene in volume ratio of 8 to 4.

6. The procedure according to claim 1, wherein the industrial naphtha reformate is diluted with a paraffinic alcohol which is ethyl alcohol, isopropyl alcohol, n-propyl alcohol, or combinations thereof in a volumetric ratio preferably 5 to 1.5.

7. The procedure according to claim 1, wherein the industrial naphtha reformate is mixed with toluene and iso-propyl alcohol in a volumetric ratio 1:0.7:0.3, further comprising executing a single wash for a continuous period of 72 hours.

8. The procedure according to claim 1, wherein the industrial naphtha reformate is mixed with toluene and iso-propyl alcohol in a volumetric ratio 1:0.7:0.3, further comprising performing a wash in three 24-hour cycles using recirculation of the solvent mixture.

9. The procedure according to claim 1 or 7, further comprising washing the coke of the catalyst for at least 72 hours.

10. The procedure according to claim 1 or 8, further comprising washing the coke of the catalyst for 24 hours, recycling the recovered solvent back to the bed containing the deactivated catalyst for 24 hours, and washing yet again to complete recirculation to 72 hours washed with this solvent mixture.

11. The procedure according to claim 1, further comprising washing with a reformate modified at 50% volume by addition of toluene and iso-propyl alcohol in a ratio of 1:0.7:0.3 volume during 72 hours once through.

12. The procedure according to claim 1, wherein the procedure is applied in-situ of the reactor containing the deactivated catalyst with treatment times ranging from 24 hours to 72 hours.

13. The procedure according to claim 1, wherein the procedure is applied in-situ, causing a decrease in surface carbon between 18.7% and 27.7 weight %, and recovering catalyst active sites as determined by an increase of MoS.sub.2 species observed by XPS from about 57.7% in the deactivated catalyst to about 70% in the catalyst after the procedure.

14. The procedure according to claim 1, wherein the hydrodesulfurization catalyst comprises metal sulfides of molybdenum and nickel.

Description

BRIEF DESCRIPTION OF THE FIGURES OF THE INVENTION

(1) FIG. 1. Shows the decrease in the content of ppm sulfur in diesel hydrotreating process @360 C. of a deactivated catalyst compared with the values obtained by the same catalyst under In-Situ procedures to recover its activity (Example 2, Example 3 and Example 4) of this invention.

DETAILED DESCRIPTION OF THE INVENTION

(2) The present invention relates to a procedure for washing of contaminants poisons of a deactivated catalyst during hydrotreating of primary light gas oil in a refinery. The washing additive consists of hydrocarbons 3-12 carbon atoms of different chemical families, particularly in smaller proportion of the group of alcohols, a higher proportion of mono-aromatic group and a significant proportion of the hydrocarbons group C5+ called specifically naphtha reformate which it is the product of catalytic reforming of naphthas at the refinery. It is therefore an object of the present invention, to provide a method for washing the contaminants of an industrially deactivated catalyst from primary light gas oil hydrotreating, which through the runtime accumulate on the outer surface of the catalyst.

(3) According to the above, by the procedure of this invention the catalytically active sites contaminated with coke are unblocking active sites, in order to increase the hydrodesulfurization (HDS) catalytic activity without damaging the metal sulphides phases of molybdenum and nickel present.

(4) It is also an objective of the present invention the partial recovery of the HDS activity of a diesel hydrotreating catalyst deactivated by coke with a carbon content of 12-14 weight-%.

(5) The procedure used in this invention includes preparation of a mixture of hydrocarbons of different chemical families, 40-60% of a mono-methylated aromatic hydrocarbon, in 12-17% of an oxygenated hydrocarbon of ROH formula where R may be a saturated alkylic containing the hydroxyl radical in the internal carbon; and contains 20-30% volume of linear and branched aliphatic hydrocarbons of 5 to 12 carbon atoms, including any fraction of cyclic paraffin.

(6) The procedure for preparation of the solvent mixture used in this invention consists of the following steps, measuring the volume used in the evaluation unit according to the volume of catalyst bed. This is important because the process of this invention recommends a liquid hour space velocity (LHSV) from 5 to 1 hour1, more preferably between 2.5 and 2.0 hours1 which means a waste of solvent per hour minimum, double of volume of the catalyst bed.

(7) Taking into account a calculation basis of 1 cubic meter (m.sup.3) of deactivated for the recovery process of the deactivated catalyst HDS activity catalyst industrially. Based on the above it is determined in the solvent mixture should control a constant flow of 2 cubic meters (m.sup.3) per hour.

(8) In order to obtain a mixture suitable for the recovery procedure of the HDS activity of the deactivated catalyst industrially required that the hydrocarbon mixture is vigorously stirred to be homogeneous during the washing procedure.

(9) The specific mixture of solvents for contaminants washing type: aliphatic carbon, aromatic carbon, sulfur, iron showing to be active to remove less of aliphatic carbon present in the catalyst, a smaller amount of aromatic carbon, fewer sulfur of sulfides present and a slight amount of iron among other contaminants. Specifically, when the deactivated catalyst, study matter of this invention which had been operating for five years in a primary light gas oil hydrodesulfurization unit at industrial level.

(10) With this washing additive is possible to solve aliphatic carbon compounds present in the deactivated catalyst, which are also responsible for HDS catalyst activity decreased for blocking the active sites hydrotreating inhibiting the efficient entry reactants through the catalyst. Achieved after this treatment increase activity hydrodesulfurization primary light gas oil in more than 30% allowing in principle increase the catalyst life cycle measured as the amount of processed hydrotreating barrels per kilogram of catalyst.

(11) Hydrocarbons Additive Preparation for Washing

(12) Formulate a liquid mixture to wash contaminants for use in reactivation treating of a deactivated catalyst industrially. A stream of naphtha reformate from refinery, industrial grade solvents toluene and iso-propyl alcohol are acquired. The total volume of treatment to be performed based on the volume of the catalyst bed to be treated and duration of the wash cycle, the following equation is calculated:
Minimum Required Volume (L,Volume Unit)=LHSV*H*VLC
Where:
Space velocity LHSV=used=2H.sup.1
VLC=Volume of catalyst in bed, volume (L, volume unit)
H=hours of treatment required=24 or 72

(13) Preparation of the additive mixture of solvents used in the process of the present invention requires its measurement with an instrument, the solvents used are liquid at room temperature and perfectly miscible between them, so that the mixtures employed in this invention are homogeneous and feasible to use in contaminants washing mainly carbon of the deactivated catalysts industrially.

(14) The procedure of this invention can use hydrocarbon solvents of different types: paraffinics, aromatics, naphthenes and oxygenated, although the use of nitrogen compounds is preferably avoided, to no affect the quality of diesel with nitrogenates residues in the catalyst bed, additionally it can be a strong poison for active sites of hydrotreating primary light gas oil catalysts.

Example 1

(15) As a diagnosis of the degree of aging of an industrially deactivated catalyst in hydrotreating unit Mexican primary light gas oil for five years, this sample was analyzed thoroughly, defining as a major pollutant: carbon deposited on the catalyst pores.

(16) The deactivated catalyst industrially during primary light gas oil hydrotreating was discharged and dried in an inert atmosphere in the same industrial unit, this material no longer containing adsorbed gas oil. It was characterized in terms of their main contaminants as shown in the following table.

(17) TABLE-US-00001 TABLE 1 Analysis of contaminants and active phase of deactivated catalyst. Composition Value Unit Total Carbon 14.03 weight % .sup.13C NMR: 0.66 [Aliphatic/Aromatic] w/w Total Sulfur 7.92 weight % Iron content 0.45 weight % Molybdenum content 9.04 weight % Nickel content 2.76 weight % Phosphorus 1.50 weight %

(18) It is considered important to determine the type of carbon deposited on the deactivated hydrotreating catalyst, this finding is done by .sup.13C Nuclear Magnetic Resonance (NMR) of the solid state where a relationship is obtained [w/w] to [4/6 ratio] of aliphatic carbon against aromatic carbon for this sample.

(19) To evaluate the HDS activity of the hydrotreating catalysts, one deactivated industrially catalyst and the others, washed with solvents to reactivation, in order to measure the degree of recovery of hidrodesulfurization sites at pilot plant level. In all cases were used 60 cm.sup.3 of catalyst volume in the form of extrudates tetra lobular 1/16 diameter and as refinery feedstock, primary light gas oil from Ciudad Madero, Tamaulipas, Mexico.

(20) TABLE-US-00002 TABLE 2 Properties of primary light gas oil from Ciudad Madero, Tamaulipas Properties Value Method Density, 20/4 C. 0.8624 ASTM-D-1282 Total Sulfur 19,100 ppm ASTM-D-4294 Total Nitrogen 314 ppm ASTM-D-4629 Aromatics content 35.5 wt-% ASTM-D-5186 Mono Aromatics 20.8 wt % ASTM-D-5186 Di Aromatics 11.2 wt-% ASTM-D-5186 Poly Aromatic 3.5 wt-% ASTM-D-5186 Atmospheric Distillation C. ASTM-D-86 Start Boiling Point 236 30 295.5 50 307.6 70 319.9 End Boiling Point 349.1 Total volume 98.3% Residue 1.0% Loss 0.7%

(21) In order to have an initial measurement (baseline) of the HDS activity of the deactivated industrially catalyst, it was carried out the catalytic evaluation using a methodology to determine conversion levels by effect of catalytic bed temperature, in the first part, it was necessary an activation step with the feed of primary light gas oil for 4 hours at 360 C. of temperature in order to sulfurize the partially oxidized sites before starting 6 hours balances at 340, 360 and 380 C. including the reaction parameters shown below:

(22) TABLE-US-00003 TABLE 3 Conditions of HDS catalytic evaluation for deactivated industrial catalyst Pressure Temperature LHSV H.sub.2/HC Time kg/cm.sup.2 C. h.sup.1 ft.sup.3/bbl hours Feedstock 46 360 1.5 2000 4 LGO Madero 63 340 1.5 2000 6 LGO Madero 63 360 1.5 2000 6 LGO Madero 63 380 1.5 2000 6 LGO Madero

(23) The results obtained of this evaluation are taken as basis for the calculation of Recovery of HDS Activity of the washed catalyst to remove contaminants in the following examples.

Example 2

(24) (A) Mixture Reformate-toluene-2-propanol

(25) The washing mixture is performed at room temperature, first placing the necessary volume of reformate naphtha into a suitable container, calculating for this first solvent comprises 50 volume-%. Immediately, was added the amount of mono-aromatic solvent, i.e. toluene with 35 volume-% ratio. While the iso-propyl alcohol is added in 15 volume-% respectively.

(26) As in Example 1 a volume of 60 mL deactivated catalyst in tetra lobular extruded form 1/16 inch diameter, which is placed in a reactor of the evaluation unit to pilot plant level is used.

(27) In this example conditions used of In-Situ washing of contaminants are shown in table 4.

(28) TABLE-US-00004 TABLE 4 Operating conditions for In-Situ Cleaning of pollutants using Reformate- iso-propyl alcohol-Toluene in one step without recirculation Pressure Temperature LHSV Nitrogen/HC Time kg/cm.sup.2 C. h.sup.1 ft.sup.3/bl hours 30-80 30-70 2.0 1200 72

(29) The total volume solvent mixture used was 8.64 liters corresponding to [72 hours120 ml]=8,640 ml.

Example 3

(30) (B) Mixture of Washing Industrial Nature Stream (Reformate)

(31) The washing mixture in this particular case is exclusively the reformate industrial stream obtained from Ciudad Madero refinery, which consists of a hydrocarbons mixture with high percentage of toluene, naphthenes and fewer quantity of paraffins, all in the range from 5 to 12 carbon atoms. For this procedure it was possible to reduce the washing time based on the response of recovery HDS activity of the deactivated industrial catalyst, since longer times, the effect was not positive.

(32) In this example the following in-situ contaminant washing conditions where the treatment time is reduced for better catalytic response, see Table 5.

(33) TABLE-US-00005 TABLE 5 Operating conditions for In-Situ pollutants washing using Reformate without recirculation. Pressure, Temperature LHSV, Rel. N.sub.2/HC, Time, kg/cm.sup.2 C. h.sup.1 ft.sup.3/bl hours 30-80 30-70 2.0 1200 24

(34) The total volume of solvent used was 2.88 liters, corresponding to 24120 ml=2,880 milliliters of Reformate

Example 4

(35) (C) Mixture Reformate-toluene-2-propanol (with 3 Cycles of Recirculation)

(36) This procedure is done with the same solvent mixture used in Example 2, but with the difference in methodology that washing solvent includes recirculation in three cycles of 24 hours in order to save solvent and minimizing the hydrocarbons used during contaminants washing. The conditions used are shown in Table 6, where solvent consumption reduction does not affect the treatment time.

(37) TABLE-US-00006 TABLE 6 In-Situ Washing Conditions using Reformate-Toluene-2-Propanol with recirculation (3 cycles) Pressure, Temperature LHSV, Rel. N.sub.2/HC, Time, kg/cm.sup.2 C. h.sup.1 ft.sup.3/bl hours Solvents 10-80 30-70 2.0 1200 72 Reformate- Toluene- 2propanol

(38) The total volume of solvents mixture was only 2.88 liters each 24 hours and the solvents are recycled three times (cycles).

(39) This methodology was effective even though the spent solvent was not cleaned in the reactor outlet, before recirculating back to the catalyst bed.

Example 5

(40) To evaluate the effectiveness of washing treatments of deactivated catalyst using three different procedures: Washing procedures A, B and C (Examples 2, 3, and 4 respectively) compared with the activity of deactivated catalyst (Example 1) using the same evaluation methodology for HDS activity using primary light gas oil shown in Table 3 above.

(41) TABLE-US-00007 TABLE 7 Comparison HDS catalytic activity of deactivated catalyst versus In-Situ washed catalysts at pilot plant Example 2 Example 4 Reformate- Example 3 Reformate- Toluene- Only Toluene- 2propanol Reformate 2propanol (72 h) (24 h) (3 cycles Deactivated Once through Once through Recirculation) Temperature weight-% weight-% weight-% weight-% 340 C. 91.6 94.8 93.7 95.0 360 C. 96.8 98.7 98.4 98.5 380 C. 99.1 99.7 99.7 99.7

(42) It is noted that even the deactivated catalyst has catalytic activity and that this can be further increased after In-Situ washing, according to the examples 2, 3 and 4.

(43) Additionally, hydrodesulfurization (HDS) activity were higher for Examples 2 and 4 @340 and 360 C. using Reformate-Toluene-2-propanol (one step and with recirculation at medium pressure respectively).

(44) At 380 C. HDS activities were similar for all the washed catalysts by the procedure of this patent around 99.7%, indicating a limit of recovery in the active sites for these catalysts.

(45) TABLE-US-00008 TABLE 8 Data obtained in diesel product (ppm sulfur) using the deactivated catalyst versus In-Situ washed catalysts at pilot plant Temperature Deactivated Example 2 Example 3 Example 4 C. S ppm S ppm S ppm S ppm 340 1652 987 1197 951 360 636 237 308 293 380 177 57 65 66

(46) Quality hydrotreated primary light gas oil is measured in parts per million of sulfur, in the case of deactivated catalyst a quality value of 250 ppm was taken like a production base, Example 2 achieves this quality at calculated temperature of 359.65 C. While the other options require 364.77 C. and 363.79 C. respectively.

(47) Therefore, it can be considered that the solvent mixture: Reformate-Toluene-Isopropyl alcohol is better to reactivate the HDS catalytic function as the starting run occurs at temperature of 360 C. to 237 ppm S as can be seen in Table 8. While examples 3 and 4 to the same temperature condition obtained 308 and 293 ppm of sulfur respectively.

(48) TABLE-US-00009 TABLE 9 Relative Characterization of Deactivated catalyst versus In-situ washed Catalysts at pilot plant Deactivated Example 2 Example 3 Example 4 Carbon, weight % 14.07 10.2 11.4 10.9 BET Surface, m.sup.2/g 118 139 130 122 Pore Volume 0.22 0.28 0.25 0.26 Pore diameter 92 78 86 87 Aliphatic Carbon % 40.5 37.9 31.5 31.97 Aromatic Carbon % 59.5 62.1 68.5 68.03 .sup.RMN [Alif/Arom] Ratio 0.68 0.61 0.46 0.47

(49) When comparing the deactivated catalyst versus in-situ solvents washing catalysts, we can mention that the improvement is given by reduction of total carbon in the catalysts, this is about 22-28%. The specific area is increased after solvent washing, as well as the pore volume. The effect is inverse for the average pore diameter decreasing values of 92 to 78-86 Amstrong. About the carbon type, a decrease is observed only in the region of aliphatic carbon, while aromatic carbon was increased. The carbon NMR [Aliphatic/Aromatic] ratio for catalysts washed in-situ with solvents were lower than in the deactivated catalyst.

(50) TABLE-US-00010 TABLE 10 Characterization by XPS of the active sites of deactivated catalyst versus in-situ washed catalysts at pilot plant. Deactivated Example 2 Example 3 Example 4 MoS.sub.2 (Mo3d) 57.7 70.13 70.28 69.66 NixSy (S2p) 39.8 41.08 26.85 40.43 NiMoS (S2p) 0.0 11.29 22.22 14.89

(51) In Table 10 can be confirmed that the active species of the washed catalyst with are higher than deactivated catalyst, this is evidence that the process for reactivating deactivated catalysts was successful regarding the improvement of the active sites present.

(52) Particularly for the species MoS.sub.2 increased 57.7% to average values of 70% in all washed cases. While sulfur species attributed to combined phase: NiMoS increased from 0 (deactivated) to 11.29, 22.22 and 14.89% (Examples 2, 3 and 4) respectively.

Example 6

(53) As a measure of the impact on the solvent used in the coke washing of deactivated catalyst in Example 3, the sulfur content of the contaminated reformate at the output of in-situ recovery treatment was analyzed. To reduce the sulfur content of the reformate obtained after washing, a study adsorption using alumina support of high porosity (AP) in one step at room temperature and as second alternative separation by Soxhlet equipment at 130 C. was performed. The results of the sulfur present in these streams are presented in the following table.

(54) TABLE-US-00011 TABLE 11 Cleaning for In-Situ contaminated Reformate used to recover HDS activity of deactivated catalyst Stream Total Sulfur (ppm) Procedure Stage Reformate Input 0.0-0.5 Feed Contaminated reformate 24 h 288 Discharged Alumina Adsorption AP 184 Room temperature Separation by Distillation: Light fraction <130 C. 14 HDS (95 wt-%) Heavy fraction >130 C. 274

(55) According to the above table, the recovered solvent is feasible to integrate into the gasoline pool if it is distilled into two fractions at a cutting temperature of 130 C., or integrated as a diluent loading the hydrotreating process of catalytic naphtha and that its sulfur content is very low, 0.0288 wt-% sulfur versus 0.28 wt-% typical value of fluid catalytic cracking (FCC) naphtha. Or otherwise you can send completely the contaminated reformate as a feed for hydrotreating process like primary naphtha, FCC or coker naphthas to recover this valuable stream of high octane number (90-95).

REFERENCES

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