Presulfided red mud as a first-stage catalyst in a two-stage, close-coupled thermal catalytic hydroconversion process

A process for the production of transportation fuels from heavy hydrocarbonaceous feedstock is provided comprising a two-stage, close-coupled process, wherein the first stage comprises a hydrothermal zone into which is introduced a mixture comprising a feedstock and dispersed activated or presulfided red mud having demetalizing and coke-suppressing activity, and hydrogen; and the second, close-coupled stage comprises a hydrocatalytic zone into which substantially all the effluent from the first stage is directly passed and processed under hydrocatalytic conditions.

BACKGROUND OF THE INVENTION 
The present invention relates to processes for the hydroconversion of heavy 
hydrocarbonaceous fractions of petroleum. In particular, it relates to a 
close-coupled, two-stage process for the hydrothermal and hydrocatalytic 
conversion of petroleum residua using "activated" or presulfided red mud 
as a first-stage catalyst. This activated red mud is made from the mineral 
waste residue of the aluminum processing industry and has improved 
effectiveness for demetalation and inhibition of adverse coke formation in 
the first stage. 
Increasingly, petroleum refiners find a need to make use of heavier or 
poorer quality crude feedstocks in their processing. As that need 
increases, the need also grows to process the fractions of those poorer 
feedstocks boiling at elevated temperatures, particularly those 
temperatures above 1000.degree. F., and containing increasingly high 
levels of undesirable metals, sulfur, and coke-forming precursors. These 
contaminants significantly interfere with the hydroprocessing of these 
heavier fractions by ordinary hydroprocessing means. These contaminants 
are widely present in petroleum crude oils and other heavy petroleum 
hydrocarbon streams, such as petroleum hydrocarbon residua and hydrocarbon 
streams derived from coal processing and atmospheric or vacuum 
distillations. The most common metal contaminants found in these 
hydrocarbon fractions include nickel, vanadium, and iron. The various 
metals deposit themselves on hydrocracking catalysts, tending to poison or 
deactivate those catalysts. Additionally, metals and asphaltenes and coke 
precursors can cause interstitial plugging of catalyst beds and reduce 
catalyst life. Such deactivated or plugged catalyst beds are subject to 
premature replacement. 
Additionally, in two-stage processes similar to this, thermal hydrotreating 
reactors are very susceptible to the adverse formation of coke on various 
components of the reactor. In particular, it has been found that coke 
builds up significantly on the walls of the reactor and that this coke 
build-up, if unchecked, will eventually cause the reactor to plug up, 
thereby necessitating time-consuming and expensive rehabilitation. It is 
the intention of the present invention to overcome these problems by using 
as a catalytic agent in the thermal, first stage of a two-stage, 
close-coupled hydroconversion process, mineral waste from the manufacture 
of aluminum, commonly known as red mud. It has been further found that the 
activity of the red mud can be significantly enhanced prior to its 
addition to the process by pretreatment sulfiding or "presulfiding". The 
action of red mud as a catalyst in a first-stage hydrothermal reactor 
including the presulfided red mud induces demetalation and some 
hydroconversion and suppresses adverse coke formation with the reactor, 
particularly on the reactor walls. The treated effluent from the first 
stage is then passed, close-coupled to a second-stage hydrocatalytic 
reactor where it is hydroprocessed to produce high yields of 
transportation fuel. 
Prior Art 
Various processes for the conversion of heavy hydrocarbonaceous fractions, 
particularly, multi-stage conversion processes include U.S. Pat. No. 
4,366,047, Winter et al.; U.S. Pat. No. 4,110,192, Hildebrand et al.; U.S. 
Pat. No. 4,017,379, Iida et al.; U.S. Pat. No. 3,365,389, Spars et al.; 
U.S. Pat. No. 3,293,169, Kozlowski; U.S. Pat. No. 3,288,703, Spars et al.; 
U.S. Pat. No. 3,050,459, Shuman; U.S. Pat. No. 2,987,467, Keith et al.; 
U.S. Pat. No. 2,956,002, Folkins; and U.S. Pat. No. 2,706,705, Oettinger 
et al. 
Various processes using red mud in hydroconversion or coal liquefaction are 
also known, including U.S. Pat. No. 3,775,286, Mukherjee et al.; U.S. Pat. 
No. 3,936,371, Ueda et al.; U.S. Pat. No. 4,075,125, Morimoto et al.; U.S. 
Pat. No. 4,120,780, Morimoto et al; Japanese Pat. No. 532643, 1978, 
Takahashi; and West German Pat. No. 2,920,415, Simo et al. 
SUMMARY OF THE INVENTION 
In accordance with the present invention, there is provided a two-stage, 
close-coupled process for the hydroprocessing of a heavy hydrocarbonaceous 
feedstock into transportation fuels boiling below 650.degree. F. using 
presulfided red mud as a thermal zone catalytic agent. At least 30 volume 
percent of the feedstock boils above 1000.degree. F. and the feedstock 
contains greater than 100 parts per million by weight of total metal 
contaminants. 
The process comprises introducing a mixture comprising the feedstock and 
activated red mud which has been presulfided prior to introduction. The 
activated red mud has sufficient catalytic activity to suppress adverse 
coke formation under incipient coking conditions and to induce 
demetalation, in the first-stage hydrothermal zone in the presence of 
hydrogen. The feedstock and red mud mixture is introduced into the 
hydrothermal zone in preferably upward essentially plug flow, under 
conditions sufficient to substantially demetalate the feedstock and to 
convert a significant amount of hydrocarbons boiling above 1000.degree. F. 
to hydrocarbons boiling below 1000.degree. F. 
Substantially all or at least a substantial portion of the effluents of the 
first-stage hydrothermal zone is rapidly passed directly and preferably 
upflow, in a close-coupled manner, into a second-stage catalytic reaction 
zone at a reduced temperature relative to the first-stage hydrothermal 
zone. The effluent is contacted with hydroprocessing catalysts under 
hydroprocessing conditions, and the effluent from said second-stage 
catalytic reaction zone is recovered. 
Alternatively, the activated red mud is dispersed within the 
hydrocarbonaceous feedstock, hydrogen is added, and the resultant 
dispersion is heated to a temperature in the range of between 750.degree. 
F. to 900.degree. F. The heated dispersion is then introduced into the 
first-stage hydrothermal zone in a preferably upward, essentially plug 
flow configuration, and the processing proceeds as summarized above. 
DETAILED DESCRIPTION OF THE INVENTION 
The present invention is directed to a process for the hydroprocessing of 
heavy hydrocarbonaceous feed-stocks, a significant portion of which boils 
above 1000.degree. F., to produce high yields of transportation fuels 
boiling below 650.degree. F. The process is a two-stage, closed-coupled 
process, the first stage of which encompasses a hydrothermal treating 
zone, wherein the feedstock is substantially demetalated while at the same 
time reducing or suppressing adverse coke formation within the first-stage 
reactor, particularly on the reactor walls. It is also anticipated that 
some hydrogenation may occur in the first-stage hydrothermal zone. 
The catalytic agent which induces the coke reduction and demetalation is an 
activated or presulfided mineral waste known as red mud. The 
hydrothermally treated feedstock is then passed directly and without 
substantial loss of hydrogen partial pressure into a hydrocatalytic 
treatment zone, wherein the hydrothermal zone effluent is catalytically 
treated to produce an effluent suitable for further treatment into 
transportation fuels. 
The feedstock finding particular use within the scope of this invention is 
any heavy hydrocarbonaceous feedstock, at least 30 volume percent of which 
boils above 1000.degree. F. and which has greater than 100 parts per 
million by weight total metallic contaminants. Examples of typical 
feedstocks include crude petroleum, topped crude petroleum, reduced 
crudes, petroleum residua from atmospheric or vacuum distillations, vacuum 
gas oils, solvent deasphalted tars and oils, and heavy hydrocarbonaceous 
liquids including residua derived from coal, bitumen, or coal tar pitches. 
The heavy hydrocarbonaceous feedstocks finding particular use in this 
invention contain very high and undesirable amounts of metallic 
contaminants. While various metals or soluble metal compounds may be 
present in the feedstock, the most debilitating include nickel, vanadium, 
and iron. These metallic contaminants cause hydroprocessing catalysts to 
deteriorate rapidly and as well as adversely affecting selectivity. 
Depending on the metal, the contaminants can enter the catalyst pores 
(nickel and vanadium) or plug the interstices in the catalyst particles 
(iron). The result is deactivation of the catalyst, and/or plugging or an 
increase in the pressure drop in a fixed bed reactor. 
Thermal hydroprocessing of the heavy feedstocks of the present invention 
also gives rise to significant and adverse amounts of adverse coke 
formation particular on the surfaces of the reactor, and more particularly 
on the walls of the reaction vessel. It has been found that using the 
activated red mud of the present invention as a first-stage catalytic 
agent significantly reduces the coke formation in a thermal reactor, 
especially on the walls, and that the coke formed is deposited on the 
particles themselves as opposed to the reactor walls and thereby removed 
from the reactor. If not removed, the coke will build up and eventually 
plug the reactor. The precipitation of asphaltenes and other coke 
precursors is also significantly reduced using activated red mud in the 
thermal stage. 
In the preferred embodiment of the present invention, activated or 
presulfided red mud is mixed with the heavy hydrocarbonaceous feed to form 
a slurry, preferably a dispersion or uniform distribution of particles 
within the feed, which is introduced into a first-stage thermal reactor. 
The catalytic agent finding use in the thermal stage or zone of the 
present invention is a fine particulate substance known as red mud. Red 
mud is the mineral residue or waste resulting from the production of 
aluminum by the Bayer process; specifically, the insoluble residue 
remaining after the digestion of alumina from bauxite using caustic soda. 
The composition of red mud varies with the type of bauxite from which it is 
derived. Typically, however, it contains 30-42 weight percent iron 
compounds, ordinarily Fe.sub.2 O.sub.3 and particularly .alpha.-Fe.sub.2 
O.sub.3, and other iron-metal hydrates, 18-25 weight percent Al.sub.2 
O.sub.3 or Al(OH).sub.3, 13-20 weight percent SiO.sub.2, particularly 
.alpha.-SiO.sub.2, 2-5 weight percent TiO.sub.2, some CaCO.sub.3, and 8-12 
weight percent attributable to ignition loss. 
It has been found that by pretreating the red mud with a sulfiding agent, 
such as hydrogen sulfide, the activity of red mud is significantly 
increased. It is believed that the presulfiding has the effect of 
converting some or substantially all of the iron oxides in the mineral 
waste into pyrrhotites of the general formula Fe.sub.1-x S, preferably 
Fe.sub.7 S.sub.8. It is these pyrrhotites which are believed to 
unexpectedly enhance the activity of the red mud in the first-stage 
thermal zone. 
In a preferred embodiment, the mineral waste is presulfided by packing 
untreated red mud into a reactor and heating it to a typical temperature 
range of from about 500.degree. F. to 3000.degree. F., preferably 
600.degree. F. to 900.degree. F. A mixture of hydrogen and hydrogen 
sulfide gases, wherein the hydrogen sulfide comprises from 1 to 99 percent 
by volume, preferably from about 5 to 25 percent by volume of the mixture, 
are metered into the presulfiding reactor at a rate of from about 0.1 to 
10 ft.sup.3 /hr., preferably 0.01 to 1.5 ft.sup.3 /hr., and maintaining a 
pressure of from 50 to 3500 psig, preferably 200 to 500 psig. The 
pyrrhotitic composition may be adjusted or controlled by varying the 
temperature, residence time, or hydrogen to hydrogen sulfide ratio. 
It has also been found that presulfiding is superior to in situ sulfiding 
as by hydrogen sulfide or elemental sulfur addition in the hydrothermal 
zone. Mossbauer, X-ray, and scanning electron microscopy studies of the 
red mud reveal two prominent forms of iron: Fe.sub.2 O.sub.3 and hydrated 
forms, and mixed Fe, Al, Ca oxide hydrates. During in situ sulfiding, 
apparently only the Fe.sub.2 O.sub.3 is sulfided to pyrrhotite species. 
This accounts for only about one-half of the iron. 
Presulfiding, on the other hand, has been found severe enough to convert 
substantially all of the iron, namely, both the Fe.sub.2 O.sub.3 and the 
Fe, Al, Ca oxide hydrates, to pyrrhotite, and therefore effectively all of 
the iron, resulting in more efficient hydrogen distribution. The 
particular size of the activated red mud can vary according to a variety 
of factors; generally, however, it is a maximum of 40 mesh U.S. standard 
sieve series, and preferably under 100 mesh with an average diameter of 
from 5 microns to 50 microns. The activated red mud is present in the 
mixture in a concentration relative to the feedstock of from 0.01 to 10.0 
percent by weight, preferably 0.1 to 2.0 percent by weight, and most 
preferably less than 1.0 percent by weight. It is believed that the red 
mud derives its catalytic activity from the inclusion of transition 
metals, particularly iron, within the material. 
In an alternative embodiment, the red mud may be presulfided by treating 
with a sulfur-containing liquid such as carbon disulfide, or 
sulfur-containing hydrocarbons, such as dimethyl sulfide, dimethyl 
disulfide, etc., i.e., polyalkyl sulfides and polyalkyl polysulfides. The 
preferred process conditions for this presulfiding include a liquid feed 
rate of from about 10 to 1000 ml/hour, a temperature of 200.degree. F. to 
1000.degree. F., a pressure of from 50 to 3500 psig, and conducted in the 
presence of hydrogen or a hydrogen/hydrogen sulfide mixture flowing at a 
rate of about 0.1 to 10 ft.sup.3 /hour. 
The feedstock-activated red mud mixture is introduced into the first-stage 
hydrothermal zone. Hydrogen is also introduced, either co-currently or 
counter-currently, to the flow of the feedstock-red mud slurry, and may 
constitute either fresh hydrogen, recycled gas, or a mixture thereof. It 
has also been found, however, that improved conversion may be effected by 
using recycle gas containing at least 2 percent hydrogen sulfide. The 
reactant mixture is then heated to a temperature of between 750.degree. F. 
to 900.degree. F., preferably 800.degree. F. to 850.degree. F. The feed 
may flow upwardly or downwardly in the hydrothermal reaction zone, but it 
is preferred that it flow upwardly. Preferably, the hydrothermal zone is 
configured such that plug flow conditions are approached. 
Other reaction conditions in the hydrothermal zone include a residence time 
of from 0.01 to 3 hours, preferably 0.5 to 1.5 hours; a pressure in the 
range of 35 to 680 atmospheres, preferably 100 to 340 atmospheres, and 
more preferably 100 to 200 atmospheres; and a hydrogen gas rate of 355 to 
3550 liters per liter of feed mixture and preferably 380 to 1780 liters 
per liter of feed mixture. Under these conditions, the feedstock is 
substantially demetalated and a significant amount of the hydrocarbons in 
the feedstock boiling above 1000.degree. F. are converted to hydrocarbons 
boiling below 1000.degree. F. In the preferred embodiment, the significant 
amount of hydrocarbons boiling above 1000.degree. F. converted to those 
boiling below 1000.degree. F. is at least 80 percent, more preferably 85 
percent to 95 percent. 
The effluent from the hydrothermal reactor zone is directly and rapidly 
passed into a second-stage catalytic reaction zone. In this invention, the 
two primary stages or zones are close-coupled, referring to the connective 
relationship between those zones. In this close-coupled system, the 
pressure between the hydrothermal zone and the hydrocatalytic zone 
maintained such that there is no substantial loss of hydrogen partial 
pressure through the system. In a close-coupled system also, there is 
preferably no solids separation effected on the feed as it passes from one 
zone to the other, and there is no more cooling and reheating than 
necessary. However, it is preferred to cool the first-stage effluent by 
passing it through a cooling zone prior to the second stage. This cooling 
does not affect the close-coupled nature of the system. The cooling zone 
will typically contain a heat exchanger or similar means, whereby the 
effluent from the hydrothermal reactor zone is cooled to a temperature 
between at least 15.degree. F. to 200.degree. F. below that of the 
temperature of the hydrothermal zone. Some cooling may also effected by 
the addition of fresh, cold hydrogen if desired. 
It may also be desirable to subject the effluent to a high pressure flash 
between stages. In this procedure, the first-stage effluent is run into a 
flash vessel operating under reaction conditions. Separated vapors are 
removed and the flash bottoms are sent to the cooling zone to reduce the 
temperature of the first-stage effluent. Additional hydrogen may be added. 
Again, as the flash is still carried out with no substantial loss of 
hydrogen pressure through the system, the close-coupled nature of the 
system is maintained. 
The catalytic reaction zone is preferably a fixed bed type, but an 
ebullating or moving bed may also be used. While it is preferable that the 
mixture pass upward to the reaction zone to reduce catalyst fouling by the 
solid particulate, the mixture may also pass downwardly. 
The catalyst used in the hydrocatalytic zone may be any of the well-known, 
commercially available hydroprocessing catalysts. A suitable catalyst for 
use in the hydrocatalytic reaction zone comprises a hydrogenation 
component supported on a suitable refractory base. Suitable bases include, 
for example, silica, alumina, or composite of two or more refractory 
oxides such as silica-alumina, silica-magnesia, silica-zirconia, 
alumina-boria, silica-titania, silica-zirconia-titania, acid-treated 
clays, and the like. Acidic metal phosphates such as alumina phosphate may 
be also be used. The preferred refractory bases include alumina and 
composites of silica and alumina. Suitable hydrogenation components are 
selected from Group VI-B metals, Group VIII metals and their oxides, or 
mixture thereof. Particularly useful are cobalt-molydenum, 
nickel-molybdenum, or nickel-tungsten on silica-alumina supports. 
In the hydrocatalytic reaction zone, hydrogenation and cracking occur 
simultaneously, and the higher-molecular-weight are converted to 
lower-molecular-weight compounds. The product will also have been 
substantially desulfurized, denitrified, and deoxygenated. 
In the process parameters of the hydrocatalytic zone, it is preferred to 
maintain the temperature below 800.degree. F., preferably in the range of 
650.degree. F. to 800.degree. F., and more preferably between 650.degree. 
F. to 750.degree. F. to prevent catalyst fouling. Other hydrocatalytic 
conditions include a pressure from 35 atmospheres to 680 atmospheres, 
preferably 100 atmospheres to 340 atmospheres; a hydrogen gas rate of 355 
to 3550 liters per liter of feed mixture, preferably 380 to 1780 liters 
per liter of feed mixture; and a feed-liquid hourly space velocity in the 
range of 0.1 to 2, preferably 0.2 to 0.5. 
Preferably, the entire effluent from the hydrothermal zone is passed to the 
hydrocatalytic zone. However, since small quantities of water and light 
gases (C.sub.1 to C.sub.4) are produced in the hydrothermal zone, the 
catalyst in the second stage may be subjected to a slightly lower hydrogen 
partial pressure than if these materials were absent. Since higher 
hydrogen partial pressures tend to increase catalyst life and maintain the 
close-coupled nature of the system, it may be desired in a commercial 
operation to remove a portion of the water and light gases before the 
stream enters the hydrocatalytic stage. Furthermore, interstage removal of 
the carbon monoxide and other oxygen-containing gases may reduce the 
hydrogen consumption in the hydrocatalytic stage due to the reduction of 
carbon oxides. 
The product effluent from the hydrocatalytic reaction zone may be separated 
into a gaseous fraction and a solids-liquids fraction. The gaseous 
fraction comprises light oils boiling below about 150.degree. F. to 
270.degree. F. and normally gaseous components such as hydrogen, carbon 
monoxide, carbon dioxide, water, and the C.sub.1 to C.sub.4 hydrocarbons. 
Preferably, the hydrogen is separated from the other gaseous components 
and recycled to the hydrothermal or hydrocatalytic stages. The 
solids-liquids fraction may be fed to a solid separation zone, wherein the 
insoluble solids are separated from the liquid by conventional means, for 
example, hydroclones, filters, centrifugal separators, cokers and gravity 
settlers, or any combination of these means. 
The process of the present invention produces extremely clean, normally 
liquid products suitable for use as transportation fuels, a significant 
portion of which boils below 650.degree. F. The normally liquid products, 
that is, all of the product fractions boiling above C.sub.4, have a 
specific gravity in the range of naturally occurring petroleum stocks. 
Additionally, the product will have at least 80 percent of sulfur removed 
and at least 30 percent of nitrogen. The process may be adjusted to 
produce the type of liquid products that are desired in a particular 
boiling point range. Additionally, those products boiling in the 
transportation fuel range may require additional upgrading or clean up 
prior to use as a transportation fuel. 
The following examples demonstrate the synergistic effects of the present 
invention and are presented to illustrate a specific embodiment of the 
practice of this invention and should not be interpreted as a limitation 
upon the scope of that invention. 
Additionally, the results of examples and comparative examples listed in 
the subsequent Table 1 were taken from inspections of the liquid effluent 
of the first-stage hydrothermal zone in order to demonstrate the 
effectiveness of the present invention. Had they been processed, 
close-coupled, through the second-stage hydrocracking zone, the 
distinction between the catalyst as shown by the product composition would 
not be as sharp for purposes of demonstrating the effectiveness of the 
process. The effect on the second-stage catalyst life and the amount 
region for effective conversion as well as the increased amenability of 
the first-stage products to second-stage catalytic processing remains the 
distinctive advantage.

EXAMPLES 
EXAMPLE 1 
A slurry of 0.25 weight percent red mud presulfided with hydrogen sulfide 
according to the method detailed above and 99.75 weight percent Beta 
Atmospheric Residuum (Beta AR) was passed upflow into a first-stage 
hydrothermal zone maintained at a temperature of 825.degree. F., 1 SHSV, 
2000 psig of hydrogen, and 5000 SCF/Bbl recycle gas rate. A portion of the 
product was collected for analysis through a high pressure letdown system. 
The first-stage effluent is passed, close-coupled, into a second-stage 
catalytic stage containing a fixed bed of hydroprocessing catalyst 
comprising a half charge of cobalt/molybdenum on an alumina base and a 
half charge of nickel/molybdenum on an alumina base, maintained at 
essentially the same pressure, and a temperature less than that of the 
first stage. 
EXAMPLE 2 
A slurry of 0.25 weight percent presulfided red mud and 99.75 weight 
percent Beta AR was processed as in Example 1 except that the hydrogen 
make up was replaced with a hydrogen/hydrogen sulfide mixture containing 
approximately 6 volume percent H.sub.2 S, and the recycle gas was not 
scrubbed for H.sub.2 S. 
EXAMPLE 3 
(Comparative) 
A slurry of 0.25 weight percent red mud (not presulfided) and 99.75 weight 
percent Beta AR was processed according to Example 1. 
EXAMPLE 4 
(Comparative) 
A slurry of 2.0 weight percent red mud (not presulfided) and 98.0 weight 
percent Beta AR was processed according to Example 1. 
EXAMPLE 5 
(Comparative) 
A slurry of 2.0 weight percent red mud (not presulfided) and 98.0 weight 
percent Beta AR was processed according to Example 2. 
EXAMPLE 6 
(Comparative) 
A slurry of 2.0 weight percent red mud (not presulfided) and 98.0 weight 
percent Beta AR was processed according to Example 1, except that 2.5 
weight percent elemental sulfur was added. 
The results of the first-stage analyses of the various examples are 
tabulated below In Table 1. 
TABLE 1 
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EXAMPLE 
1 2 3 4 5 6 
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Additive Red Mud 
Red Mud 
Red Mud 
Red Mud 
Red Mud 
Red Mud 
Presulfided 
Presulfided W/H.sub.2 Syngas 
W/Element S 
W/H.sub.2 Syngas 
Weight Percent 
0.25 0.25 0.25 2.0 2.0 2.0 
Conversion, % 
85 83 77 76 76 44 
1000.degree. F.+/1000.degree. F.- 
Removal, % 
Metals (Ni & V) 
75 71 65 64 64 27 
Asphaltene 52 50 38 49 49 17 
Rams Carbon 
59 52 41 45 45 21 
Sulfur 47 48 48 51 51 24 
Product Inspections 
H/C 1.53 1.53 1.49 1.50 1.54 1.50 
.SIGMA. C.sub.1 -C.sub.3, C.sub.4 + 
1.93 2.02 2.17 2.21 2.17 1.07 
Solids (% feed) 
0.97 1.26 1.88 0.54 0.67 0.38 
H.sub.2 Consumption 
680 680 430 650 620 395 
SCF/Bbl 
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