Note: Descriptions are shown in the official language in which they were submitted.
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D-1294 RECOYERING METAL COMPOUNDS FROM USED
CATALYSTS OBTAINED FROM
HYDROPROCESSING HYDROCARBON FEEDSTOCKS
BACKGROUND OF INVNTION
. .
This invention pertains to recovering valuab1e metal
compounds deposited on used cata1ysts. It pertains par-
ticularly to a process for treating used catalysts from
hydrocarbon catalytic hydroconversion processes to recover
deposited nickel and vanadium compounds from the catalyst as
metal oxides.
Used catalysts obtained from catalytic hydroprocessing
of hydrocarbon feedstocks such as petroleum, shale oil and
tar sands bitumen contain undesired nickel and vanadium com-
pounds dS metdl contaminants on the catalyst. Removal of
these metal contaminants is an essential part of regenera-
tion of the spent catdlysts. It is known to recover such
deposited metals from spent catalysts by grinding the cata-
lyst to fine particle size and then recovering the metals by
ch~mical processes, which thereby destroys any fur~her use-
fulness of the catalyst. In my U.S. Patent No. 4,454,240,
issued June 12~ 1984, it is disclosed that acid treatment of
spent catalysts with dilute sulfuric acid solution can re-
move most of the vanadium and nickel eompounds without ad-
versely affecting the active elements of the catalyst and
thereby provide a useful regenerated catalyst material. The
spent acid solution contains vanadium in sulfate or oxy-
sulfate form and nickel in sulfate form. However, that
patent does not disclose any method for recovering the
valuable metals such as vanadium and particularly nickel
from the s~ent acid solution.
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SUMMARY OF INVENTION
The present invention provides a process for recovering
metals compounds deposited on used catalyst from the cataly-
tic hydroprocessing of hydrooarbon feedstocks. The process
comprises treating the used catalyst containing deposits of
metals such as nickel and vanadium by adding a dilute fresh
acid solution to the used catalyst to extract and remove the
metal deposits, and then mixing the resulting spent acid
solution from the acid treatment step with a hydroxide solu-
tion such as ammonia, ammonium hydroxide, sodium hydroxide
solution or mixtures thereof sufficient to neutralize the
spent acid to a pH of between about 7 12, and forming metal
salts precipitates ,uch as nickel hydroxide and hydrated
vanadium trioxide. The precipitated material is then
separated from the neutralized acid solution such as by a
filtration step to recover useful metal salts and a filtrate
liquid. The filtrate liquid can be discarded, and the metal
salts are converted to metal oxides intermediate products by
heating the sa-lts to about 300C. If desired, the metal
salts can be mixed with granular carbon and further heated
successively to their respective melting temperatures of the
metals to reduce the metal oxides and recover the molten
metals in substantially pure form.
Alternatively, by successively increasing the pH of the
neutralized spent acid solutiolls, the nickel and v~nadium
salts can be a~vantageously recovered separately from the
process~ By first adding to the spent acid solution only
sufficient hydroxide solution to provide a pH of about
3.5-6.0, nickel hydrox~de i5 precipitated out and removed
such as by filtration~ The nickel hydroxide upon oeing
heated to about 230C produces nickel oxide. Upon further
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addition of a hydroxide solution to the resulting filtrate
liquid sufficient to provide a pH of about 9-12, hydrated
vanadium trioxide and any other metal salts present will be
precipitated and can also be removed such as by filtration.
The hydrated vanadium trioxide upon being heated to about
300C produces useful vanadium oxide.
It is an important advantage of the present invention
that it recovers valuable metals such as nickel and vanadium
compounds deposited on used catalyst during catalytic
hydroprocessing operations without damaging the catalyst,
thus not only permitting the treated catalyst material to be
reused but also recovers the valuable deposited meeals in
relatively pure form from the spent acid solution.
BRIEF DESCRIPTION OF DRAWING
FIG~ 1 is a schematic flow diagram of a catalyst rege-
neration and metals recovery process according to the inven-
tion.
FIG. 2 is d schematic flow diagram showing furnace
heating the recovered metal salts to produce molten metals.
DESCRIPTION OF INVENTION
As shown in FI~. 1, a hydrocarbon feedstock 10 such dS
coal, petroleum or tar sands bitumen containing metal com-
pounds is catalytically hydroconverted at elevated tempera-
ture and pressure in reactor 12 containing particulate cata-
lyst 12a to produce a reacted effluent stream 11. IJsed
catalyst particles containing metal deposits such as nickel
and vanadium from the hydrocarbon hydrogenation reaction
process, are withdrawn at 13 from the catalytic reactor 12,
and passed to a solvent washing step 14, which uses a suit-
able solvent such as naphtha or toluene to remove substan-
tially all the heavy oils from the used catalyst. The re-
sulting oil-free catalyst at 15 is then passed usually as d
batch to catalyst treatment tank 16. A fresh dilute acid
solution 17 which will extract and remove metal deposits
from the catalyst, such as preferably 10-25% sulfuric acid
solution, is added to the tank 16 to extract the metals
deposits and thereby regenerate the used catalyst. Other
dilute acids which can be used for treating the catalyst to
extract deposited metals therefrom include but are not
limited to citric acid, hydrochloric acid and nitric acid or
mixtures thereof. The regenerated catalyst material is
removed at lB and can be passed to further treatment steps,
such as a wash step to remove acid and a carbon burn-off
step, prior to reuse of the catalyst in reactor 12.
From the catalyst acid treatment tank 1~, the spent acid
solution is withdrawn at 19 containing the dilute spent acid
along with metal salts including nickel sulfate and vanadium
sulfate compounds, and is passed to acid neutralizing vessel
20. Sufficient basic material such as ammonia gas, ammonium
hydroxide, sodium hydroxide or mixtures thereof is added at
21 to the treating vessel 20 and mixed with the spent acid
solution using mixing means 22 to neutralize the acid solu-
tion therein to a pH of about 3.5-12 at a residence time of
5-30 minutes, thereby forming a precipitate material con-
taining nickel and vanadium salts. The preferred basic
material added at 21 for neutrali~ing the spent acid solu-
tion is ammonia gas, because no water is thereby added to
the solution for later removal. Ammonium hydroxide can be
advantageously used for neutralizing the acid because of its
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lower costs and availability to the process, such as being a
by-product from an H-Oil process for catalytic hydroconver-
sion of petroleum feedstocks. Also, ammonium hydroxide
addition produces ammonium sulfate precipitate, which is a
desirable ~y-product as compared to sodium sulfate.
Alternatively, sodium hydroxide can also be used, as well ds
mixtures of hydroxides.
From acid neutralizing vessel 20, the resulting neutra-
lized liquid and precipitate material is wi~hdrawn at 24,
and the precipitated hydroxide salts are separated from the
liquid sulfate solution and removed by suitable means 26,
such as by a filtration step or by centrifuging, after which
the sulfate filtrate solution at 27 can be discarded, if
desired.
From filtration at 26 the filtered precipitate solids
are removed at 28 and are water washed at 29 to remove any
remaining sulfates at 29~. The washed solids material is
then heated in tank 30 to d temperature of about 230C so as
to drive off water vapor at 31, such as by passing a hot gas
32 upwardly through the solids to heat the solids. Useful
heating gases at 32 can include air, carbon dioxide and
nitrogen. The resulting metal oxides are recovered at 34 as
productO These metal oxides recovered at 34 can be advan-
tageously reused either in the manufacture of fresh cata-
lyst, or for other appropriate uses.
Alternatively, if it is desired to recover nickel oxide
and vanadium oxide separately from the spent acid solution,
the metal salts precipitate removed at 28 as a filter cake
material is mixed with gran~ldr carbon at SO~as shown in
FIG. 2~ The moist filter cake mdterial is usually mechani~
cally mixed by mixer 53 with charcoal powder in a weight
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ra~io of metal salts to carbon in a range of 2/I 4/1. The
resulting filter cake and carbon mixture at 52 is then
introduced into a furnace 54, in which a suitable inert gas
atmosphere is maintained, such as by nitrogen or C02. The
furnace ~4 is usually heated electrically such as by
resistance wire coils 55. The filter ~ake~carbon mixture is
then heated therein to first evolve water vapor and the
water of hydration, and then further heated successively to
the melting temperature of the various metals contained in
the filter cake material. Such heatins of the metal salts
with carbon converts the metal salts to oxides and reduces
the metal oxides to their respective metals and evolves C0
and C02 gases at 57, generally according to the following
principal reaction equations:
V23 ~zC -~2V~ C02 + C0
NiO + C - ~ Ni + C0
The filter cake material is heated to temperatures
corresponding to the melting temperature of the respective
metals and held at each temperature for sufficient time to
allow each ~olten metal to drain from the furnace at 58 in
substantially pure metdl forms. The appropriate furnace
temperature for the various metals in the filter cake
materiat are listed below:
ME~AL MELTING TEMPERATURE, C
_
Aluminum 660
Nickel 1455
Iron 1530
Yanadium 1710
Molybderlum 2620
As another alternative embod~nent of the invention for
remo~ing the nicXe1 and vanadium separately in relatively
pure forms, only sufficient hydroxide solution is added at
21 to neutralize the spent acid in treating vessel 20 to
provide a pH of about 3.5-5Ø Under these conditions, nic-
kel hydroxide is precipitated, separated at filter 26 and
removed at 28. The nickel hydroxide is water washed at 29
to remove any remaining sulfates at 29~, and heated at 30 to
230-300C by upflowing hot gas 32, and converted to nicke1
oxide product at 34. Furthermore, additiona1 hydroxide
solution is added at 35 to first filtrate solution 27 in
mixing tank 36 and mixed using mixing means 37 to produce a
pH therein of at least about 9.0 and preferably 9.5-12.0,
the salts of vanadium and other metals such as aluminum,
iron and molybdenum are then also precipitated and withdrawn
at 38. The precipitated solids are separated at 40 by suit-
able means such as filtration as generally disclosed above
to produce second filtrate liquid stream 41. The filtered
precipitate solids material is removed at 423 and water
washed at 43 to remove any remaining .sulfates at 43l3. The
washed material is then heated in tank 44 by an upflowing
gas such as air to a temperature of about 240-300F to drive
off all water vapor at 45 by hot gases 46 passed upwardly
through the bed to produce oxides of vanadium and other
metals, which are recovered at 48.
This invention will be further described by reference to
the following example, which should not be construed as
limiting the scope of the invention.
EXAMPLE 1
Used particulate catalyst removed from a petroleum cata-
lytic hydroconversion process and containing metals deposits
including nickel and vanadium was treated with a 15~ solu-
tion of sulfuric acid at 180F temperature for 10 minutes to
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extract and remove the metal deposits including nickel and
vanadium in the form of sulfates and oxysulfates. The
resulting spent acid solution was treated with ammonia gas,
ammonium hydroxide, and sodium hydroxide in a mixing tank
for 10 minutes residence time to neutralize the acid to pH
of 9.0 and form a precipitate metal salts material. The
liquid and precipitate material was filtered, and the
resulting filter cake material ~as water washed and heated
to 300C (572F) to produce oxides of nickel and vanadium.
Results are summarized in Table 1..
TABLE 1
METALS COMPOUNDS RECOVERY FROM SPENT ACID SOLUTIONS
CONTAINING METALS SALTS
Used Catalyst Treated, lb l.~ 1.0 ~,
Metals Deposits
on Used Catalyst, W %
Nickel 1 1 2
Vanadium 10 10 8
Fresh Acid 15% 15~ 15~
Used for TreatmentSulfuricSulfuricSulfuric
Spent Acid Solution
Containing Metals, lb 2. 5 2. 5 3.0
Neutralizing Agent Ammonia AmmoniumSodium
Added to Spent Acid Gas HydroxideHydroxide
pH of Neutralized Acid
Solution 9 9 g
Metal Salts Precipitate
Material Recovered, lb. 0.10 0.10 0.12
Metal Oxides
Recovered from Fi~lter Cake:
NiO~ % 6.1 6 20
V2 3~ % 89 89 62
Others, ~ 4.9 5 18
Metal Salts Contained in
Filtrate Liquid, lb0.37 0.87 0.74
Analysis of Salts in
Filtrate Liquid
Nickel 0.02 0.03 0.01
Vanadium 0.01 0.01 0.01
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From the above results, it is seen that substantially
all the metal salts including nickel and vanadium contained
in the spent acid solution were recovered from the precipi-
tate in the form of metal salts or oxides, and negligible
metals remained in the acid solution. These metal salts can
be converted by heating to metal oxides product at high
recovery.
Although this invention has been described broadly and
in terms of certain preferred embodiments, it will be
understood that modifications and variations to the process
can be made within the spirit and scope of the invention,
which is defined by the following claims.
