JPS5992027A - Removal of metal contaminant from catalyst used in buffer oxalic acid - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed description of the invention] Kiyo 1J41i, Z.
(ro-conversion) relates to the removal of metal contaminants from catalysts. In particular, the present invention relates to the selective removal of metal contaminants from catalysts on refractory oxide supports without deterioration by treatment with oxalic acid solutions.

Hydroconversion catalysts used in the treatment of petroleum IJli feedstocks are used to reduce coke buildup (but Id-U
p) and contamination with metals typically found in crude oil. 7. The use of acids in culms is known. U.S. Pat. Removal of iron and other metals from catalysts for catalytic cracking.Aqueous oxalic acid solutions are preferred.U.S. Pat.
No. 020,239 describes the removal of vanadium from molybdenum-containing catalysts using an aqueous glycolic acid solution. Other hydroxy acids and compounds similar to glycolic acid are unsatisfactory because they simultaneously remove molybdenum.

Concentration adjustment is preferred to avoid leaching of aluminum from the carrier material. US Patent No.? , 79/, 9g No. 9 involves contacting a catalyst with an aqueous oxalic acid solution prior to combustion removal of coke deposits, and hydroprocessing (hydroprocessing (containing group 1 or group 2 metals)).

processing) describes the removal of vanadium from the catalyst. In Example 1, contaminated catalyst particles are boiled with oxalic acid to remove vanadium preferentially over nickel or molybdenum. British Patent No. 8, No. 15.3Sg contains the reverse introduction 11111, which states that inactivated J (↓
1#>ξ゛ or Vl group catalyst is first subjected to a coke combustion and removal step, and then washed with an oxalic acid aqueous solution having a degree of sharpness of θSi4 to saturation. Contact AJ with oxalic acid (if time is limited, 1 on the catalyst metal will not be removed).

U.S. Patent No. q, θg9. gθ No. 2 and No. 7, /. No. 2゜2,000, a hydrogenation devaluing catalyst containing Group VIB and (-)Vlil metals on a refractory support was regenerated using combinations of oxalic acid, nitric acid, and ('itake) nitrates. arise. It is stated that the use of oxalic acid alone under conditions severe enough to remove a substantial amount of vanadium results in the dissolution of 11 bodies of alumina.

Additionally, U.S. Patent No. 3.5. ? According to No. 637, ion exchange resin contaminated with iron is regenerated by contacting the contaminated resin with oxalic acid.

Although oxalic acid is known to be useful for removing certain metal contaminants from hydroconversion catalysts supported on inorganic oxide supports such as alumina, oxalic acid is It has the disadvantage that it also dissolves or removes phase materials.

The inventors have discovered that buffering an aqueous solution of oxalic acid overcomes the above drawbacks without adversely affecting the ability of oxalic acid to remove all the contaminants.

Accordingly, the present invention provides for the removal of metal contaminants from hydroconversion catalysts comprising at least/glaze metals from the VI B group or the Vll B group or the tJ'S''1'' group supported on refractory-free JA oxides. The method comprises contacting the contaminated catalyst with a buffered aqueous oxalic acid solution. In another embodiment of the invention, at least one of alumina or silica (or silica-alumina closed zeolite) or clay is added. Contaminant metals are removed from the catalytic cracking catalyst containing the catalytic cracking catalyst by a method comprising contacting the contaminated catalytic cracking catalyst with a buffered aqueous oxalic acid solution.

The method of the present invention using buffering allows the use of SURl12 at various sensitivities without dissolving the gold Mr% biride support typically used in hydroconversion catalysts. Moreover, even at high extraction temperatures, the oxalic acid solution and the contaminated catalyst can be kept in contact for a long time without removing the catalytically active metal from the 4u form.

Buffering the oxalic acid also allows it to be used to regenerate the catalytic cracking catalyst without dissolving the catalyst.

The hydroconversion catalysts in question are those in which either the active catalyst component or the support material is susceptible to attack by mineral acids and/or organic acids. During normal commercial use, these catalysts become contaminated 11 with metal contaminants and coke formation and become deactivated. Acid regeneration of the deactivated catalyst is used to remove metal contaminants. However, if the support or catalyst is susceptible to acid attack, a substantial problem arises since loss of support also results in loss of active catalyst components. Such losses are often unacceptable or the contact time of the acid with the contaminated catalyst is limited to such an extent that substantial metal contaminants cannot be removed.

Particularly problematic hydrocondensation catalysts include catalytic cracking catalysts, reforming catalysts, and resid conversion catalysts.
included. Catalysts for catalytic cracking are acidic metal oxides such as alumina, silica, silica-alumina, zeolites, clays, especially acid-treated clays, silica-zirconia, silica-magnesia, alumina-boria, silica-titania. The above catalyst for catalytic cracking as a carrier and hydrogenation
Dehydrogenating metals (e.g. Co.

N1. (W, V, No, Pt, Pd or a combination thereof) becomes a hydrogen cracking catalyst. In general, VIB gold or Vtl B metal or group II metal or a combination of these, supported on an acidic carrier as described above, is subjected to residic conversion,
1 noforming contact of the gods (- John (catalytic hydroconv)
erslon). Condensed Chemical Dictionary (Condensed Chemical Dictionary)
Chemical Dictionary) No. 9'
It is stationary in the periodic table in the negative side of #-. Preferred catalytic materials are alumina-straddled silica-alumina or zeolites, alone or in combination, as CO or MO-straddled Re or platinum group metal phase.

Metal contaminants can arise from metal components used during production, either in the feedstock or in the reaction column and transfer lines. Examples of metal contaminants that can be removed with oxalic acid are 1d, W)z, vanadium, nickel, sodium, magnesium, chromium, copper, strontium, lithium, lead, etc. Such metals are generally undesirable because they can lead to catalyst deactivation through catalyst poisoning and/or blockage.

As previously mentioned, oxalic acid extraction to remove gold FJi contaminants can also result in acid attack of the acid-sensitive phase and/or active catalyst components. Additionally, some oxalic acid treatments require high temperatures and (necessarily) high concentrations of acid, thus exacerbating the above problems. The present inventors have discovered that these problems can be solved by buffering oxalic acid without adversely affecting the ability of oxalic acid to extract gold kJ≦contaminants.

The buffering agent of the present invention is a buffering agent capable of buffering an oxalic acid aqueous solution within a pH range of 0 to /θ, preferably 5 to 1A, and 5O. Preferred buffers are those that do not contain sufficient specific rA group cations or IT A group cations to produce catalytic delta effects.

Examples of preferred 444J'l agents are ammonium salts of weak acids such as ammonium acetate, ammonium citrate, ammonium formate, ammonium lactate, ammonium valerate, ammonium propionate, ammonium urinary v-y'ammonium, etc., or mixtures thereof. .

Mixtures of different buffers are known to extend the range of pH that can be adjusted compared to separate buffering agents. The use of ammonium salts of weak acids eliminates the negative effects of adsorption of cations in alkaline buffers or alkaline earth slowing agents. Alkaline buffers also contain cations, which are known to be a severe poison for many hydroconversion catalysts.

A metal wheel 13 gylating buffer may also be used to aid in the selective removal of metal contaminants from the hydroconversion catalyst. Oxalic acid itself is known to gyrate and remove niobium and zirconium from ion-exchange columns [“The Gmistry Op.
Lanthanides (The Chemistry of Lan)
thanldes), 'T-Moeller (T-Mo
Reinhold Publishing Corporation (Reinhold Publishing Corporation)
ishing Corporation), -=
Knee York, /wa A3. Pg/-g! ;]. Buffers with different metal binding capacities are N82 GOICH2N
HC,l-;2SO3N.

N82COCH2N (CHz COOHLa, bicine).

Glycylglycine, ONCH2CH25OII H,
) is tricine.
Buffers for pHandMetal
ton Control): D, D, Perrin and B, Denbsey (D, D, Perrin and
B, Dempsey) + John.

Willie and Thump (John Wiley)
and 5oz).

New York, P10g]. Glycine derivatives are known to be strong complexing agents for iron and other metals. Hexanoic acid and di(O-hydroxyphenyl)
Acetic acid is also known to be a strong complexing agent for iron and other metals, and can be added to buffer compositions ['Photometric Link and Fluorometric Methods of Analysis. metal bar) /
(Photometer and Fluoromet
rlcMethods of Analysis,
MetalsPart /)j F, D, Snell (F
, D. 5nell, John Wiey and 5ons.

New York, 797g, P7t3). Shinishitsu 1ζ9
Enhancement of the rate and extent of metal contaminant removal from hydroconversion catalysts by using strong complexing agents in the buffer solution, in addition to ions, could lead to improved metal contaminant extraction schemes. can.

Another ill J! for the removal of metal contaminants from hydroconversion catalysts! The group of IIj agents includes water/
Useful buffering agents in non-aqueous solvent systems are included. For example, 9
In 0% MeOH//θ% H20 solution, 001 molar oxalic acid, 007 molar oxalic acid, 007 molar
Buffer H to lAλ3. Otsu θchi MeOH/Da θchihh
o In solution, this same buffer gives a pH of 25 g ['Buffer as for pH and Metals]
Ion Conte c+ -/l/ (Suffers f
or p)1. and MetalIon Cont.
rol) 'D, D, Perrin and B,
John Wiley and 5ons
, = knee yoke, /97'l'', Pg'1-g
g]. Aqueous/non-aqueous systems are useful for hydroconversion catalysts or lano metal contaminant removal because alumina dissolution is greatly suppressed compared to aqueous systems.

In some cases, the buffer can contain low concentrations of Group 1B TA acid components. In this case, such a buffer system is effective in removing metal contaminants from the hydroconversion catalyst.
It can be used for Examples of such aqueous buffers include phenyl hv
and sodium phenylacetate, acetic acid and sodium acetate, cono-phosphate and sodium hydroxide, potassium heptalate and sodium hydroxide, sodium hydrogen maleate and sodium hydroxide, potassium dihydrogen phosphate and sodium hydroxide,
Sodium pyrophosphate and hydrogen chloride, blclne
) and hydroxide) IJium. All of the above buffers have a pH range that is determined by the concentration of the buffer components.

Other aqueous buffers useful with oxalic acid for the removal of metal contaminants from Hydroconversion 1 media include glycine and hydrogen chloride, imidazole and hydrogen chloride, 2. '1. B-trimethylpyridine and hydrogen chloride, N-ethylmorpholine and hydrogen chloride, tris(hydroxymethyl), aminomethane and hydrogen chloride, J-amino--methylpropane-/
, 3-diol and hydrogen chloride, jetanolamine and hydrogen chloride, ammonia and ammonium chloride.

In some cases, broad range buffers such as 1, citric acid and NazHPO4 (pH, 2,6- to θ) may also be useful in removing metal contaminants from no-hydroconversion catalysts. Other known broad-spectrum buffers include biperazine
l117 salt, glycylglycine and sodium hydroxide; citric acid, 2HPO2, dietherbarbituric acid and sodium hydroxide; boric acid, citric acid and ortho17. i
1. Sodium salt.

The required buffering agent l' depends on the concentration of oxalic acid used. The oxalic acid concentration can be in the range of θθθ0/M to left θM, and is preferably in the a1 range of θθ/ to ΩθH. The new wall concentration of buffering agent is 11] sufficient to keep the pH of the oxalic acid within the desired range. As the a degree of oxalate increases, it generally becomes more
A given buffer of 1° is required.

The temperature range is about θ°C to about /θθ°C, preferably 2
The temperature is 0 to 75°C. Temperature tJ' lower than this, gold L.
”! Particularly beneficial in terms of pollutant removal 75h i) (+;
＜ , Jj口１ζO, [There is a possibility that excessive acid attack of the catalyst metal may occur.

Unlike regular 7-oxalic acid, buffered oxalic acid can be contacted with deactivated catalyst for extended periods of time without dissolving the support material. The method of contacting the catalyst with the buffered oxalic acid solution is not critical. The deactivated catalyst can be soaked in a buffered oxalic acid solution. Then, at predetermined time intervals, samples of the catalyst or buffered quenching solution are removed and tested for the extent of metal contamination.

Alternatively, continuous extraction can be performed, for example by internal circulation of buffered oxalic acid in a self-flow extractor.

Preferred embodiments for the removal of metal contaminants from hydroconversion catalysts typically include one or more metals (preferably 'i L<
r, 1', Re or noble metal) in combination with pt
The present invention relates to the regeneration of reforming catalysts including: Reforming catalysts gradually become contaminated with metals such as Fe, Pb, Cu, Ca, and Na, but Fe is particularly troublesome.

05M oxalic acid to contaminated, γ-AI203-supported p
When slurried with tt or pt/lri or Pt/Re catalysts and heated, significant amounts of support and precious metals are removed 7 along with the desired Fe contaminants. In contrast, ammonium acetate-buffered oxalic acid extraction of the same catalyst system selectively removes Fe and results in very small catalyst losses that are attributable to mechanical losses rather than chemical attack on the γ-alumina support. . F using a buffered oxalic acid bath
8 removal, a low temperature of 1.20 to 75°C is preferred.

After extraction, the Pt/Re catalyst was transferred to S2 in the presence of 0□.
It was baked at 0° C. for an hour. Amphibiotic catalyst H2 and CO・
The chemisorption values of the fresh catalyst were almost the same and showed no toxic effect or surface modification due to the buffered oxalic acid solution treatment.

The Fe-extracted Pt/Ir catalyst was compared for naphtheliforming activity Ql against an unextracted catalyst containing 035 wt% θ and a fresh pt/+r catalyst.

After 700 hours, the extracted catalyst had only a 25% reduction in reforming activity compared to the fresh catalyst, compared to the reduced reforming activity of the catalyst that was not extracted with the buffered oxalic acid solution. was 70 cm.

Hereinafter, the method of the present invention will be further explained by examples.

The catalyst has a surface area of SET/30~/qθtr? γ- of /f
It was supported on At20dji body.

P t /Re/A t20S This platinum-rhenium bimetallic catalyst is a commercially available sample, with an initial composition of θiPt, θ3
It was q6Re, θ9chi Gt (unless otherwise specified, all chis are city 11'').

Pt/Ir/At203 This platinum-iridium dimetallic catalyst was a commercially available sample. The fresh catalyst contains θ3% Pt, θ3% lr, θ7% Ct-. A number of spent Pt/lr/Az,Os samples were also obtained from the refinery.

Pt/At20! - This -metallic platinum catalyst was a commercially available sample, and its composition was θ3×Pt and θ7×Ct.

and Pt/Ir/A403 catalyst using standardized iron nitrate aqueous solution and initial wetness method (1ncipient w
After adding a known amount of Fe and drying under air at 7.2θ°C for 6 hours, the impregnation was heated under 1.20% Ot/He (300°C
c 1 minute) and calcined at 270° C. for a period of time to ensure the decomposition of nitrate.

Example/ This example shows the chemical adsorption of Fe for noble metal bimetallic catalyst
Shows harmful effects. Shinfeld and Yates (Si
nfelt and yates) is J, cata
Hydrogen and carbon monoxide chemisorption studies were performed using the conventional glass vacuum apparatus I□'I described in l*g+g2 (/wootsu7).

The absorption 7h values of aqueous and carbon monoxide iJ, k sources, and evacuated samples were measured at 23:l:2°C. Typically, the hydrogen adsorption value at 1ftL, fc, and pressure θ for 3θ minutes at each adsorption point is determined by the saturation power of the metal (5atura).
The H/M ratio was calculated assuming that the tion coverage was the same. The hydrogen adsorption value at pressure θ is Ben5on and Paradart (Bo
udart) and Wilson (Wison)
and Hall [J, Catal,
, 'I, 7θl/ri65) and /7. /9θ(
/97θ)], it was determined by extrapolation of the high-voltage straight line portion of the equimixture line. The GO/M ratio was calculated by measuring the carbon 11 adsorption value for the reduced exhaust sample and assuming that this value represents the sum of carbon monoxide weakly bound to the A40s support and strongly bound to the metal surface. . The sample was then evacuated for 70 minutes at room temperature/0-” Tor
r), the crosstalk such as carbon monoxide was measured. Since the λ-th equimixture measures only carbon monoxide weakly adsorbed on the phase, the difference between the two equimixers gives the amount of carbon monoxide strongly bound to the metal component. The amount of strongly bound carbon monoxide at 100 Torr is calculated from the metal saturation coverage (5a
turattoncoverage).

Hydrogen chemisorption properties of fresh Pt/Re and Pt/Ir catalysts and iron impregnated fcPt/Re and pt/lr catalysts are shown in Table 1.

Pt/Re-supported alumina and θ impregnated with iron
35APt/θJchi Re/A4o3 θ 0.
4t /θ0θ/θ 03 73 O3 Otsu θλ 5゜θ3%Pt10.3%lr/A40s 0 7
7 /θ0θ03 /4t g, 2 θ/θ /3 7Otsu03Otsu /θ 59 θgθ o, g 4t'7 (a) Iron added as nitrate. After iron impregnation, the tentacles were calcined at 1.27 θ C for 6 hours under θ% Oz/He (S θ cc/min) to ensure separation of nitrates.

(b) At room temperature, the number of chemically adsorbed hydrogen atoms in the catalyst (Sθθcc /min) at 2.0
Time was saved.

(c) Normalized variance The first column in Table 1 shows the hydrogen adsorption value of the iron-contaminated catalyst.
It is normalized with respect to the adsorption values of fresh Pj/Re and Pt/Ir catalysts. It was found that the hydrogen chemisorption capacity of the artist's metal catalyst decreased systematically as the iron concentration increased. At an iron concentration of θ3, the hydrogen adsorption value of the artist's metal catalyst is 4tθ~50% lower than the adsorption value of the fresh catalyst.

The [θ/noble metal molar ratio of the catalyst containing θ/~0g of Fe is in the range of θ5-4. Thus, an iron concentration of θ, 2% is high enough to interact with all noble metal components present in the Pt/Re and pt/+r reforming catalysts. The significant decrease in the H/M value that occurs at low iron concentrations points to the fact that iron alloys or physically adheres to a significant fraction of the noble metal. A reduction in chemisorption capacity may inevitably lead to a reduction in reforming activity. This is because H-H and C-H bond activation processes are very important in catalytic reforming.

Example λ This example shows the effect of iron on the reforming activity of a dimetallic maple catalyst. 1, 25c operated in one pass method
In the stainless steel fixed bed isothermal water wheel addition treatment equipment of c.
A naphthalene homing reaction was performed.

The reforming experiment was carried out at 4tg7~lIgq℃, /11
．． The test was carried out under a total pressure of θ Kq/al gauge pressure L200 psig).

The weight space velocity is 2/IW, and hydrogen F, +,
It was supplied at a rate of AOOO5CFH,/BBL. A commercially available naphtha feedstock was used and the sulfur concentration was adjusted to 05 ppm K by addition of thiophene. After hydrogen reduction at 500°C, the catalyst was reduced to 6! using 8)'2S/H□ mixture. It became f. Reformate
Research method octane number (RON) analysis was conducted. Octane number was used to define relative catalytic activity (RCA).

The naphthalene homing reactions of fresh Pt/Re and Pt/Ir catalysts and iron-contaminated Pt/Re and Pt/Ir catalysts are compared in Table 2.

The relative catalytic activities clearly show that iron at θ3 has a significant detrimental effect on both bimetallic catalysts.

Similar coke formation was observed for all catalysts. The 5S-6S% lower activity exhibited by the iron-containing catalyst indicates that the noble metal is deactivated by interaction with iron. In these catalysts, the Fe/noble metal molar ratio is around
Pt.

There will be enough iron available to modify all of the Ir, Re. The reduced reforming activity is consistent with the reduced hydrogen chemical 2a capacity seen with iron-contaminated catalysts.

Example 3 Table 3 shows the solubility of r-At20s in water, oxalic acid solution, and ammonium acetate buffered oxalic acid solution.

After refluxing for 3θ minutes in H,0′, the pH of the γ-At203 slurry reaches a self-buffering level of about SO.

The acidity of Ale Ox HIO slurries is well known in the art. A slurry of A4on in oxalic acid is 70
It exhibits a pH of about λ at 0°C. Thus, AtRO,
- The acidity of the oxalic acid slurry is approximately 3 orders of magnitude greater than the acidity of the He1xosH20 slurry. At20s-Vinegar A&
It was found that ammonium oxalic acid slurry, in contrast to oxalic acid slurry, maintains a relatively constant pH value of about 100 ml. Thus, the pH of the acid value slurry is At, 0. The pH value is similar to that of an aqueous slurry. p
The value of H, is the At20 that can be recovered unchanged from the slurry.
This is reflected in the amount of 11. 1-1. Essentially complete recovery of AttOs was obtained from the oxalic acid slurry. However, the oxalic acid slurry contains a significant amount of A)
,0. easily dissolves. After refluxing for 30 minutes, approximately half of the starting amount of At20B was converted to soluble aluminum rods.

This example demonstrates the non-selective extraction of iron from a wire catalyst. Table 1 shows the results of a representative study using oxalic acid solutions for the extraction of iron from Pt, Pt/Ir, and Pt/'Re catalysts.

0, ,! 6θ at 50 °C with i' M oxalic acid solution.
After a minute, about 10% At20! l carrier is dissolved. 10
When extraction was performed at 0°C, 3θ~tIO% of At,
O, carrier dissolves. These significant losses of support are too high to seriously consider oxalic acid as an extractant for metal contaminants. High temperature <ioo
During the extraction carried out at 10°C, a significant proportion of the precious metal components are extracted along with the iron. The loss of Re is particularly significant and cannot be suppressed by lowering the extraction temperature or reducing the concentration of the oxalic acid solution.

Example S In contrast to Example G, this example demonstrates the selective extraction of iron from a noble metal catalyst using oxalic acid. The results of studies using ammonium acetate buffered oxalic acid solutions for the extraction of iron from Pt, Pt/Ir, and pt/Re catalysts are shown in Table 5.

The iron-contaminated catalyst was typically reduced under H2 before extraction with buffered oxalic acid solution.

Compared to oxalate slurry, buffered oxalate solution has A40
s Do not dissolve the carrier. −~The apparent catalytic loss of goo is
This is primarily due to mechanical losses during the passage of the slurry, rather than dissolution of the A1203 into the buffer solution. Although iron is selectively extracted, no obvious removal of lj gold H occurs even at an extraction temperature of 100°C. The extraction data further indicates that iron removal is advantageous at lower processing temperatures. This behavior is consistent with the fact that iron oxalate complexes are more stable at lower temperatures.

In the case of a Pt/Ir catalyst contaminated with iron, it is necessary to demonstrate the effect of catalyst particle size on extraction efficiency. The smaller the catalyst particle size,
It is expected that more surface will be exposed to the extraction medium.

Thus, under given extraction conditions, removal of iron and other extractable contaminants should be more advantageous with smaller particle sizes.

Consistent with this is the fact that more than 11" of iron was removed from the powdered melt.

The extraction data shown in Section S was obtained from crude slurry experiments and was not optimized. but,
By subjecting the catalyst to a fresh extraction MM:Q'P4 flat term, or by devising an extraction method such that the catalyst is continuously contacted with a buffered oxalic acid solution.
It is reasonable to believe that essentially all the iron present on a particular catalyst can be removed. Gentle oxalic acid solution is
Multi-build hydrocarbon conversion catalyst (hydroca'rbon)
conversion catalog),
It can also be used to remove iron and other extractable metals such as Na, V, Ni, Cu, etc.

Although oxalic acid is preferred for metal contaminant removal, oxalic acid can also be substituted for other organic acids in the process of the invention.

Example 6 It is known that iron can act as a poison for noble metal catalysts. This example demonstrates the beneficial effect of iron removal on the chemisorption behavior of P t /Re catalysts. The results are shown in Table 1.

When θ37 iron is added to fresh Pt/Re catalyst, H
2 and Co adsorption values decreased by about 50%. When this iron-contaminated catalyst was extracted with an ammonium acetate buffered oxalic acid solution at 50°C, the iron concentration was reduced from θ37 to 60 g%. This extraction catalyst was heated to 20% a, l at 500°C.
Calcination under He for 9 hours ensured that the last traces of extractant were removed from the catalyst surface. After the extraction and calcination steps, the chemisorption value increased to a value close to that exhibited by fresh catalyst. The restoration of the chemisorption value of the P t /Re catalyst by iron removal indicates that the buffered oxalate extractant does not poison or modify the gold scrap surface.

The redispersed Pt/Ir catalyst showed lower hydrogen and carbon monoxide adsorption values than the fresh catalyst.

X-ray diffraction measurements of the redispersed catalyst show neither a Pt nor an 11° diffraction pattern, so it is reasonable to assume that the catalyst is well dispersed. Therefore, 035 on the redispersed catalyst
The presence of % iron may be responsible for abnormally low hydrogen and carbon monoxide adsorption values. By extracting iron from the catalyst with an ammonium acetate buffered oxalic acid solution, the iron concentration was reduced from 03S to θ/T. After the standard extraction procedure, the catalyst was calcined at 1.27[theta]C under 1.2% O,/He for a period of time.

The iron-extracted and calcined Pt/lr catalyst exhibited hydrogen and carbon monoxide adsorption values that were somewhat lower than those exhibited by the redispersed catalyst. Since the iron extraction catalyst was only subjected to a calcination step at 27[theta]C, the low chemisorption values may be due to residual adsorbent adhering to the gold scrap surface. The low chemisorption values exhibited by this extraction catalyst did not adversely affect the reforming activity of this catalyst, as described below. This finding suggests that residual extractant can be removed from the catalyst at high reforming temperatures.

Example 7 In this example, 1, good dispersion pt/+r catalyst (633% Fe
The naphthalene homing activity of fresh Pt/1r
Compare the catalyst and Fθ with the extracted catalyst.

The results are shown in Table 7. The reforming reaction conditions are as described in Example C.

Table 7 Iron extraction, naphthalene homing activity supply time of alumina-supported Pt/Ir catalyst /4'3 10.2.2 /g3 2/S /θ15 /2g33! ; 101g /34t 55 /θl /Ω6 (B), θ3! ;% Fe content Otsu 4' 999
ヮ/Redispersion catalyst /3 Otsu 9'7.2
Otsu θ20g 9 left o rig 32g 93.3 'Iθ ri θ0 differential. Otsu 39 (C), iron from catalyst (B) 6.5'/θlA7
．． 23g extracted /37 /θ3. /
/7 otsuko θ9 /θ here. 155 3θS /θ/ko //kukuθ/ /θ03 97 1Ig910θ3 wo7 (a) For complete catalyst details, refer to section 1.

(t,,) RON-Research Method Octane Number (C)RC
A=relative catalyst activity The reforming activity of the medium was only 3θ% of the reforming activity. The reduced reforming activity exhibited by the endodispersed catalyst suggests that iron contamination is a deactivating/important factor. After iron extraction, the reforming activity of the extraction catalyst after 700 hours of feeding d1 is about 100% of the activity of the fresh Pt/Ir catalyst. Thus, removal of iron from endometrial samples will result in significantly more active tentacles.

on the reforming activity of Pt/Re catalysts. The harmful effects of Fe in No. 37 are shown in Table g.

Table g Iron extraction, alumina-supported Pt/Re catalyst supply time/37 10θ3 93 KoOg 9g, 3'7.2 329 9'Zg Otsu/lIO/9mu9 37 (E), θ37Chi 63 99.2
Iron-impregnated catalyst containing gθ /35 9 Otsuθ
53207 9'Al l- 27g wo/7 3Otsu 32Otsu 9θθ 32 330 g9! ; 30 20g 99.9 9/ 327 9θS '12 399 9g, 3 A Otsu 1I23 97.4' Otsu/ (a) For complete catalyst details, refer to Table O (b) RON = Research Y Left Octane 1 song (c) RC
A-Relative Catalyst Activity The reforming activity of the iron-contaminated catalyst after 3 SO hours of feeding is only Sθ less than the activity of the fresh catalyst.

The same iron-contaminated catalyst exhibited hydrogen and carbon monoxide adsorption values that were Sθ less than the fresh catalyst (see Table A). Thus, for iron-contaminated Pt/Re catalysts, there is excellent agreement between catalytic activity and chemisorption measurements. Extraction of gO% iron from this iron-contaminated Pt/Re catalyst yields a catalyst with hydrogen and carbon monoxide adsorption values and reforming activity close to those of fresh catalyst. This agreement between chemisorption values and catalytic reforming activity indicates that iron modulates bimetallic catalysts by interacting with metal components. The proportion of eyebrow metals inactivated by iron increases with increasing iron concentration.

Example g This example shows that mineral acids are not equivalent to oxalic acid in removing iron from the catalyst. 0 on Al2O2 support
．． 2g%Pt, 027%" + -20% Fe
The catalyst containing
Treatment with diluted hydrochloric acid gave the results shown in Table 9.

Table 9 Recovered catalyst Recovered catalyst treatment solution (a)! Rib (heavy 5p section) (b) (heavy multimetal) King! 1 Sat” 2 Upper” θ5 MHCt, 50me/θ
g3 θ2502 Otsu 760.25M1-IC4/θsu 5H acetic acid 3.0 93 θnear θsufu/taammonium,! ;Ome (a), 3. The θ2 catalyst (///oto inch extrudate) was heated at 700° C. for 6θ minutes.

(1)) The recovered catalyst was washed 5 times with /θθg of distilled water and dried at 720°C for an hour.

These results indicate that buffered hydrochloric acid results in large carrier losses with little iron removal.

229 Macdonagh Street, S. Plainfield, New Chassis, USA 0 Inventor: John Jay Ziemiak 1-4 Eaton Court Road, Annadale, New Chassis, USA

Claims (1)

[Scope of Claims] (1) At least / from Group III B or Group Vll B or Group Vllll supported on a refractory nuclear-free oxide.
A method for removing metal contaminants from hydroconversion catalysts containing Fili metals, the method comprising fusing the contaminated catalyst with a mild oxalic acid solution. @ Shuno solution has enough star's strength to maintain pH at λ~/θ! The method according to claim #g (1) or 0), wherein the method is modified with a III agent. (,?) The method according to claim 3 or 9, wherein the concentration of oxalic acid is θθOθ/M~SOM. (g) The temperature is about θ°C to /θθ°C. The method according to claim (1) or (9).
The method described in section 1). (B) Catalyst supported on alumina or silica-alumina or ceolite 7 Co twist length 140' or Rθ
At least platinum AA gold metal / 411! (7) Buffering the contaminated catalyst for a sufficient period of time to extract the metal contaminants without bathing the inorganic oxide. Claim No. (C) or (9)
) Method described in section. (g) 7 The range of 'l'J' If・Hft where the oxalic acid solution is a mixture of salts in a water/non-aqueous bath medium system (
Section C' or Section 1 (9) U self-loading method. (9) For catalytic cracking containing at least alumina-only silica-alumina or zeolite or clay by a method consisting of contacting a contaminated catalytic cracking catalyst with an oxalic acid solution. Gold from the catalyst 1 pollution! 1. &+ How to remove quality.