close

Вход

Забыли?

вход по аккаунту

?

Патент USA US3044963

код для вставки
July 17, 1962
3,044,953
R. H. KOZLOWSKI
REMOVAL OF AN UNDECANE-RICH FRACTION FROM A HYDRO CARBON
CONVERSION PROCESS RECYCLE
Filed March 50, 1959
10
0
m
.1
.J
o
z
E Q
<
u]
-'
m
=1 1L
l-
.
m
<
-
BCURENDYM.OLVA- CR'.FEUYALM-OVTNDIEC
‘° 2
O
r
0 Z
_ln 3
5
“
'
o
-
“>‘
._l
_
l
o
u
" E
a:
3
sa: U=
a
>
H
I
o
O.
1:
I
I
_m
>
_o
N
-2
|
o
qm
o
10
v
|
o
N
m
o
o
o
m
'AO‘BBHLVHHdINEIJ. HOdVA
INVENTOR
ROBERT
. KOZLOWSK/
States
3,044,953
Patented July 17, 1962
1
2
EXAMPLE
A petroleum distillate fraction having an initial boiling
3,044,953
REMOVAL OF AN UNDECANE-RICH FRACTION
FRQM A HYDROCARBON CONVERSION ‘PROC
ESS RECYCLE
point of about 340° F. and an end point of about 460° F.
was employed as a feed stock to the conversion zone.
A.
Robert H. Kozlowski, Berkeley, Calif., assignor to Cali
fornia Research Corporation, San Francisco, Calif” a
corporation of Delaware
Filed Mar. 30, 1959, Ser. No. 802,847
2 Saints. (61. 203-100)
distillation curve (broken line marked “A”) of this feed
is shown on the ?gure of the accompanying drawing. The
feed was one that is preferred for the particular conversion
process in that the basic nitrogen content was below 25
p.p.m. The feed, along with 6,500 s.c.f. of hydrogen per
10 barrel of total feed, was passed at a liquid hourly space
This invention relates to a process for the catalytic con
velocity (LHSV) of 1.0 through the conversion zone
version of hydrocarbon distillates. More particularly, it
wherein
the feed and hydrogen were contacted with a
relates to an improved process for converting such dis~
catalyst composed of nickel sul?de (2.5 weight percent Ni)
tillates to products boiling essentially below the feed frac
on an active silica-alumina cracking catalyst support _( 90%
tions employed.
15
SiO2—10%
A1203). The conversion zone was operated at
A process has recently been developed for the conver
a pressure of 1200 p.s.i.g., and an average temperature
in the range of from about 650° to 800° F. which provided
a 60 volume percent conversion to products boiling below
about 350° F. The unit was operated at extinction recycle,
sion of petroleum middle distillates boiling generally above
about 325° F. to high octane gasoline blending stocks boil
ing below about 325° F. The process comprises passing
such a feed, along with hydrogen, to a conversion zone for 20
. i.e., all of the conversion zone e?’luent boiling above about
350° F. was recycled to the conversion zone. A sample
of this recycle stream after 236 hours of operation (aver
age catalyst-bed temperature of about 725° F.) was taken
about 350° to 800° F. Although once-through operations
and subjected to a Hypercal distillation. The results of
are feasible, it has been found to be a great deal more
contact with a catalyst comprising a hydrogenating com
ponent dispersed on an active cracking support at a pres~
sure of at least 400 p.s.i.g. and at temperatures of from
25
e?icient and productive to recycle at least portions of the
said zone.
this distillation are shown on the solid distillation curve
“B” on the ?gure. The large plateau in the 380° to 390°
F. region, which is not present in the feed distillation
conversion zone ef?uent boiling above about 325° F. to
'
curve, is readily apparent and clearly shows the build-up
um distillate feeds having initial boiling points of from 30 and consequently the refractory nature, of this portion of
the recycle stream. Mass spectral analysis of both the
about 325° to 370° F. and end points above about 395° F.
fresh feed stock and recycle portions boiling between 380°
under conditions such that the recycle stream includes
to v390" F. gave the compositions indicated in the table
fractions boiling above about 370° F., it has been found
In operating the process with paraffin-containing petrole
below.
that a comparatively narrow boiling fraction of the recycle
Tab le
stream is extremely refractory to subsequent conversion 35
and tends to build up in said stream to a high level. This,
Composition, Vol. percent
of course, is undesirable since it requires the constant
recycling of a fraction that is essentially resistant to con
Paraf?ns:
version and thus diminishes the amount of fresh feed which
Un rl 9 ca 11 a
can be fed to the unit.
40
‘
Feed
Others ______________________________________ -_
It was found that this build-up ‘in the recycle stream of
a refractory material is largely attributable to the presence
Naphthenes :
of a single normal para?in species, namely, undecane
Aromatics:
MononucleanDinuelear ___________________________________ __
Mononuclear ________________________________ __
(B.P. 384.5° F.). Apparently this compound, entering
Dinuelear ___________________________________ ._
the system in the distillate feed, is extremely resistant to 45
the isomerization, disproportionation and selective crack
'
Recycle
22
80
l3
3
22
5
8
1
21
6
14
5
100
100
ing reactions that occur in the conversion zone under the
From the above table, it can be seen that undecane
content of the 380° to 390° P. fraction builds up to 80
volume percent, while from curve “B” it can be seen that
proved method of operation of the aforenoted recycle 50 this
380° to 390° P. fraction amounts to about 35 volume
relatively low temperature conditions employed therein.
Accordingly, the present invention is directed to an im
process which comprises reducing the undecane content
of the recycle stream that is returned to the conversion
percent of the entire 350° F.+recycle.
The recycle stream distillation curve “B” plotted on
the ?gure also shows that the large build-up of refractory
preferably the process is operated such that at least a
portion of the 375 °:L-5 ° to 395i5° F. boiling fraction of 55 compounds is largely con?ned to undecane. Thus,_no
other plateaus indicating such a large build-up are found
the conversion zone ef?uent is continuously removed from
on the recycle stream distillation curve “B,” and this
the reaction system, thereby essentially preventing any
despite the fact that some n-dodecane was present. This
material undecane build-up in the recycle stream which
has also been found to be the case when a light cycle oil
is returned to the conversion zone. This removed frac
boiling in the range of from about 400° to 500° or 600° F.
. tion, due to its high normal parai?n content, may be ad
was employed as the distillate feed to the conversion zone
vantageously used as a component in jet, diesel and other
operating with a 400° F.+extinction recycle.
,
fuels.
Zone. While this fraction can be removed in various ways,
The following example clearly shows the undesirable
build-up of undecane in the recycle stream of a hydrocar
bon conversion process of the type referred to above.
It might also be noted that the undecane build-up
occurs only when the compound is present in the initial
feed stock. This was observed by passing a feed stock
65 boiling above 400° F. into the conversion zone'at esseni
'
3,044,953
(i
tures in the range of from about 350° to 800° F. with a
3
tially the same conditions described in the example above
and recycling the 360° F.+ product. No undecane
preferred range being from about 450° to 700° F. This
relatively low temperature operation is one of the distin
guishing features of this process over conventional high
plateau was found in the distillation curve of the recycle
stream.
A third distillation curve “C” indicates a typical re— CI! emperature hydrocracking reactions.
The process can be conducted in either ?xed catalyst
cycle stream when an undecane-rich fraction is continu
ously removed from the 350° F.+ portion of the conver
bed, moving bed, ?uid catalyst or slurry catalyst systems
with the ?xed bed operation being preferred. It is possi
sion zone e?luent.
his in many cases to extend on-stream time over such
The feed stocks employed in the process are those pe
troleum distillates containing undecane and boilingabove 10 long periods that it becomes uneconomic to provide cata
lyst regeneration facilities. However, catalyst regenera
about 325° F., and preferably in the general range of
tion can be effected either in situ or in separate regenera
from about 325° to 850° F. Preferably, these feeds con
tain over about 10 volume percent aromatic hydrocarbons
and/or have basic nitrogen contents of less than 25
ppm. If the particular feed stock has a basic nitrogen
content in excess of this ?gure, a conventional ?rst stage
hydro?ning operation can be employed to denitrify the
feed. In general, suitable feeds are those generally de
?ned as naphthas, kerosene distillates, gas oils and re
cycle oils. These may be of straight-run origin, as ob
tained from petroleum, or they may be derived from vari
ous processing operations, and in particular, from ther
mal or catalytic cracking of stocks obtained from petro
leums, gilsonite, shale, coal tar or other sources.
The catalyst employed is a multifunctional catalyst
composition comprising a hydrogenating component dis
persed on an active cracking support. The latter may
tion zones,-by conventional regeneration techniques.
A preferred method of conducting the process, includ
ing the removal of the undesirable undecane-rich fraction
from the conversion zone e?luent, can be brie?y described
as follows:
The distillate feed, a recycle stream to be described and
hydrogen are passed into a ?xed catalyst bed conversion
20 zone operating within the hereinbefore de?ned conditions.
Following conversion, the total ef?uent from the conver
sion zone (reactor) is ?rst passed into a high pressure
separator from which is removed a hydrogen-rich stream
which is recycled to the conversion zone, along with fresh
make-up hydrogen. The hydrogen-lean effluent is then
passed to a low pressure separator wherein a normally
gaseous C4-(butane and lighter) stream is ?ashed off and
removed to storage. The remaining C5+ fraction is then
comprise any one or more of such acidic materials as
passed into a separation zone, in this case a fractional dis
silica-alumina, silica-magnesia, silica-alumina-zirconia
composites, as well as certain acid treated clays and simi
30
tillation column, wherein this C5+ fraction is separated
selected from any one or more of the various group VI
into the desired fractions. For example, separation can
be made into a variety of gasoline blending stocks having
various boiling ranges, an intermediate fraction rich in
undecane which is recovered and removed from the sys
tem, and a bottoms recycle stream that is returned to
and group VIII metals, as well as the oxides and sul?des
the conversion zone.
lar materials. A preferred cracking support is comprised
of synthetically prepared composites of silica and alumina
containing from about 70 to 95% of the silica component.
The hydrogenating component of the catalyst may be
It is obvious that the separation of the conversion zone
e?luent can be done in many ways. Thus, all separations
could be made in one large distillation zone, or in a plu
together with such metals as nickel or cobalt and the
various oxides and sul?des thereof. Also suitable are 40 rality of ?ash separators and/ or distillation columns.
Also, the actual boiling ranges of the product gasoline
certain group I (B) or group II (B) metals, such as
blending fractions can be varied to suit the purpose of the
copper or cadmium and their oxides and sul?des. If
particular re?ner. The important step, insofar as the
desired, more than one hydrogenating component may be
present invention is concerned, is preventing an undecane
present. The amount of total hydrogenating component
may be varied within relatively wide limits of from about 45 rich fraction, boiling inthe range of from about 375°:5"
to 395°i5° F., from being returned to the conversion
0.1 to 25%, based on the weight of the entire catalyst
zone in the recycle stream which will, under most situa
composition.
tions, boil above about 325° F. Whether the removal of
In the operation of the present process, the distillate
this undecane fraction is done in the e?luent separation
feed may be introduced to the conversion zone, in admix
thereof, representative materials being the oxides and
sul?des of molybdenum, tungsten, chromium and the like,
ture with hydrogen, as either a liquid, vapor or mixed 50 zone or zones or in a separate zone located on the recycle
stream itself is immaterial.
I claim:
1. In a hydrocarbon conversion process wherein an
the charge stocks utilized. The feed is introduced in ad
liquid-vapor phase, depending upon the temperature,
pressure, proportion of hydrogen and boiling range of
mixture with at least 2000 s.c.f. of hydrogen per barrel
of total feed (including both fresh, as well as recycle
feed), and the amount of hydrogen may range upwardly
to 15,000-20,000 s.c.f. per barrel of total feed. From
about 500 to 2000 s.c.f. of hydrogen are consumed in
most instances in the conversion zone per barrel of total
feed converted to synthetic product, i.e., that product boil
ing below the initial boiling point of the fresh feed. The
hydrogen stream admixed with the incoming feed is con
veniently made up of recycle gas recovered from the e?lu
ent of the conversion zone (and, if desired, from a ?rst
undecane-containing petroleum distillate feed having an
initial boiling point from about 325° F. to 370° F. and an
end point above about 395° F. and hydrogen are con
tacted in a conversion zone at temperatures from 350° F.
to 800° F. and pressures above 400 p.s.i.g. with a catalyst
comprising a hydrogenating component disposed on an
active cracking support, and wherein a recycle stream
having a boiling range extending above and below the
384.5 ° F. boiling point of undecane is obtained from the
effluent from said conversion zone and is returned as feed
to said conversion zone, the improvement which comprises
stage hydro?ning zone if the latter is employed), together 65 removing undecane from said recycle stream prior to
returning said stream to said conversion zone, whereby
with fresh make-up hydrogen.
undecane is prevented from building up in the system and
The pressures employed in the conversion zone are in
reducing the capacity of said conversion zone to convert
excess of about 400 p.s.i.g. and may range upwardly to
as high as 5000 p.s.i.g., with a preferred range being
fresh feed.
2. In a hydrocarbon conversion process wherein an un
from about 600 to 2500 p.s.i.g. The feed may be intro 70
decane containing petroleum distillate feed having an
duced to the conversionzone at a liquid hourly space
initial boiling point from about 325° F. to 370° F. and
velocity (LHSV) of from about 0.2 to 5 volumes of hy
an end point above about 395° F. and hydrogen are con
drocarbon (calculated as liquid) per super?cial volume
tacted in a conversion zone at temperatures from 350° F.
of catalyst, with a preferred rate being from about 0.5
to 3 LHSV.- The process may be conducted at tempera 75 to 800° F. and pressures above 400 p.s.i.g. with a catalyst
3,044,953
5
~
6
comprising a hydrogengating component disposed on an
building up in the system and reducing the capacitytof
active cracking support, ‘and wherein a portion of the
said conversion zone to convert fresh feed.
e?iuent from said conversion zone having a boiling range
extending above and below 375 :5“ F. to 395i5° ‘F. is
References Cited in the ?le of this patent
returned as feed to said conversion zone, the improvement 5
which comprises removing from said portion prior to the
return thereof to said conversion zone the fraction boiling
from 375 i5° ‘F. to 395:F:5° F. and containing undecane,
and returning only the remainder of said portion to said
conversion zone, whereby undecane is prevented from 10
I
'
UNITED STATES PATENTS
2,428,692
,
'
Voorhles -------------- -- Oct- 7' 1947
2,858,267
2,902,436
K§nnedy et a1- ———————— -- Oct- 28’ 1958
M1115 ----------- --\——--- SePt- 1' 1959
Документ
Категория
Без категории
Просмотров
0
Размер файла
438 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа