close

Вход

Забыли?

вход по аккаунту

?

Патент USA US2404436

код для вставки
Patented July 23,’ 1946
2,404,436 _
UNITED » smEs .1 ‘PATENT ore-Ice
‘v V . ISOMERIZING HYDROCARBONS
Chester 0. ‘Crawford, El Cerrito,:and'David Louis
Yabroif, Alameda, Calif., assignors ‘to Shell De
velopment Company, San Francisco, Calif., a
corporation of'Delaware
vNo Drawing. Application November 17, 1942,
.
l
lSerialfNo. 465,926
4 Claims.
‘
(Cl. 260-6835)’
2
This inventionrelates to the catalytic isomer- ‘
ization of saturated hydrocarbons ‘and relates
more ,particularly'to an improved ‘process for the
catalytic conversion of normal :or branched chain
saturated hydrocarbons, having at least ?ve car
bon atoms to the molecule, :to branched or more
highly branched chain saturated hydrocarbons
having the samenumber of carbon atoms to the
molecule.
.
of isomerization, often is vso great as to occasion
the loss of the greater part of the material
charged- A still greater detrimental effect oc
casioned by the hydrocarbon decomposition in the
presence of the Friedel-Crafts type catalysts is
the rapid deterioration of the catalyst brought
about by the products of this reaction.
Much effort has been expended in attempts to
control the tendency of the Friedel-Crafts type
Catalysts of the Friedel-Crafts type are known _~ 10 catalysts, and particularly the aluminum-halides,
to catalyze the hydrocarbon isomerization reac
tion.
However, these catalysts are also effective '
in catalyzing the decomposition of hydrocarbons.
In‘ the isomerization of a'more stable, hydrocar
bon, it is sometimes possible to favor theisomer .15
ization’ reaction by a judicious selection of tem-'
perature and pressure'conditions to such-a degree
that conversion to the ‘desired isomer is attainedv
'with a minimum of hydrocarbon decomposi‘tion.~
Processes are presently in use "which enable the R20
e?icient conversion of butane to isobutane with
but little undesired side reactions. ‘Many other
hydrocarbons, such as, for example,ethe saturated
open chain hydrocarbonslhaving five or more car
bon atoms to the .moleculeare, however, :parti'cu- ‘
to catalyze the decomposition of hydrocarbons
in non-destructive hydrocarbon conversion proc
esses to thereby enable the desired reaction to
predominate. Good results have been obtained
in certain processes by the maintenance of a high
partial-pressure of hydrogen in the'reaction zone.
The use of this gas, particularly atthe high pres
sures usually required to render it effective, in.
creases initial and operating costs considerably
and introduces di?ic‘ulties and hazards. of opera
’tion which often act as serious deterrents to
practical operation.
. _
It has vnow been found that isomerizable hy
drocarbons can be catalytically isomerized in the
absence of substantial hydrocarbon decomposi
larly proneto undergo decomposition in the pres
tion and without the need for recourse to the
ence of isomerization catalysts. Even in some .of
these cases, the ‘undesirable side reaction can be
suppressed to some degree by the use of sum
introducing into the reaction zone an aromatic
ciently mild operating conditions.
Such .con'di- .
tions often will be so mild, however, as to make
the attainment of conversions and yields indica
tive of a practical operation impossible. On‘ the
use of normally gaseous cracking suppressors by
compound of the hydrogen-donor type. By the
term “aromatic compounds of the hydrogen
donor type” or “aromatic hydrogen-donor,” as
used throughout this speci?cation'and the at
tached claims, is meant an organic aromatic com
pound capable .of liberating hydrogen under the
other hand, to use temperature conditions more‘
favorable to the ‘isomerization reaction in the ,35 conditions of execution of the isomerization re
action. In accordance with the present inven
treatment of these hydrocarbons in the absence »
tion, a hydrocarbon stream comprising an isomer
of agents ‘capable of ‘suppressing hydrocarbon de
izable. saturated’ hydrocarbon is contacted with
composition generally results in the presence of
the hydrocarbon decomposition reaction ‘to 'a- de
an isomerization catalyst of the Friedel-Crafts
gree precluding eilicient operation of the process. .40 type at isomerizing conditions in the presence
of an added aromatic hydrogen-donor.
By the term “decomposition” as used through
. The invention may be applied to the isomeriza- '
out this speci?cation and the ‘attached claims is
tion of any Visomerizable saturated hydrocarbon.
meant the rupture'lof carbonto carbon and/or
carbon to hydrogen bonds of the. hydrocarbon
It is applied with particular advantage, however,
molecule to result in the formation of hydrocar- . 45.
bons of lower molecular weight‘ than the hydro
carbon treated. ‘The detrimental effect ‘of the ,v
to the isomerization of- the more readily degraded
hydrocarbons, such as, for example, the open
chainwpara?‘inic hydrocarbons having at least ?ve
hydrocarbon decomposition reaction upon the
isomerization process manifests itself in many
carbon atoms to the Fmolecule of normal and
charge by converting it to materials ‘other than
may comprise not merely one isomerizable hydro
branched structure. The invention isnot limited
ways, any one of which is generally su?icient to .50
. to the treatment of materials consisting essen
render the process impractical. This reaction
tially of a single hydrocarbon. It may be applied
causes the loss of substantial amounts of ‘the
to the treatment of hydrocarbon mixtures which
an isomeric form of the material treated possess
carbon but in addition one :or more other satu
ing the same number of; carbon ‘atoms to the 55 rated hydrocarbons which may or may not be
molecule. This loss in the treatment of the more
capable of isomerization under the conditions of
readily degraded hydrocarbons such aspentane,
execution of theprocess. While the invention is
methyl pentane, and the like, in many of the
processes utilized heretofore, at temperatures en
ization of saturated open. chain or para?lnic hy
applied withparticular advantage to the isomer- ’
abling the attainment of even amoderate-rate so drocarbons; it'may be applied tothe treatment of
2,404,436
3
, 4"
more readily-degradedSaturatedEhYdrOcarbOns in
isomerizable naphthenic. hydrocarbonsrsuch as,
‘the .liquid'fph'aseis usuallyv 'e?ected at. somewhat
for example‘, methylv cyclopentane, dimethyl cy
clopentane, methyl cyclohexane, or hydrocarbon I = _
mixtures comprising them,
The invention may" '
also be applied to the treatment under isomeriza;
ing conditions of hydrocarbon fractions‘compris
ing substantial amounts ofisomerizable hydro-.
carbons, such ‘as, for example, fractions] of
straight run gasoline, casinghead'gasoline;lfractions Vof the distillate products obtained in the
lower temperatures. Suitable temperatures com
prise, for example, about 0° C. to about 150° C.
.Itis to he pointed out that operating tempera
tures have been largely limited by the scope of
l’ ,the'accompanying' decomposition reaction and
"thatconsequently the present invention enables
'ffefflicientuoperation at somewhat higher tempera
107.."tures
"than ‘possible heretofore in the absence of .
The
suppressors
11 isomerization reaction may be executed at sub
a hydrocarbon .decomposition
thermal or catalytic conversion-pf hydrocarbons,
atmospheric, atmospheric, or superatmospheric
etc.
The hydrocarbons or hydrocarbon , mixtures
»,
' pressures. In the caseof liquid phase operation
“ treated are preferablysubstantially free of mate'
rials, the presence of which adversely a?ects the
a su?iciently high superatmospheric pressure is, ,
15
of‘cours'e, maintained to keep at least a substan
activity of the catalyst." Ole?ns, diole?ns, .aro
tial part of the reactants in'the'liquid'phase.
matic hydrocarbons, or other detrimental impuri
ties in the hydrocarbon- or hydrocarbon mixture
to be treated are preferably removed prior to
" vThe hydrogenedonor introduced into ‘the/reac
comprise one or more of such steps as mineral
, acid re?ning, hydrogenation, -alkylation,"contact
I of liberating hydrogen-under the'iscmerization
condition'semployed. - Suitable hydrogen-donors
tion zone'in‘ accordance withthe invention may
isomerization by a ‘suitable treatment which may 20 comprise broadly an aromatic compound capable
‘comprise v"organic compounds containing an'aro
matic radical having attached directlyto the
with clay or with part of the spent catalyst, sol
vent extraction, etc.
‘_
I
'
I
‘ _
aromatic‘ nucleus, ‘more than one hydroxy= or
The is'omerization process may be carriedv out
with any of the known Iisomerization' catalysts.
amino groups, or a hydroxyl and an amino group.
Other hydrogen‘ atoms in the aromatic nucleus
Suitable isomerization'ca'talystsare, for example,
those of the Friedel-Craftsltype, such in par
may be replaced by suitable organicconstituents.
There is a markedidifference,‘ however,‘ in the
ease yvith 'whichth'e side ‘chains are ‘cleaved from
an aromatic nucleus in' the presence o‘fFriedel
Crafts type catalysts, larger 'alkyl 'ch'ains'being
'ticular as aluminum chloride and aluminum bro;
mide; The catalysts maybe used as such or de
posited upon or mixed with various carrier sub
stances such vas¥activated alumina,‘ "activated
separated far more ' readily than the- ‘shorter vside
bauxite, activated carbon, or other suitable ad
chainsm ‘Even though'thefhydrogenédonors need
sorptive support materials;'' also modi?ed cata
lystsrof' this type such as the mixtures‘ of alumie
be introducedinto the reaction‘ zone in suchv rela
tively small-amounts that any products resulting
num halides with other metal'halides either in
the solid or molten state, or the me. Particularly
, from their decomposition would'have only a minor
in?uence on'catalyst‘ activity, the'use ‘of aromatic
effective catalysts‘ comprise aluminum chloride
dissolved in 'a mixture of V'molten metal halides
such- as, for instance, molten mixtures compris
ing AiCls—NaCl—-.KC1, AlClse-SbCléf, VAlC13—-
'40
matic nuclei‘fof which contain’ side ‘chains, the
use of those containing not more than three and
Other: suitable catalysts comprise a halide salt of
preferably not more than two carbon atoms in
thelongest unbroken side chain‘ is generally more
aluminum in admixture with, a halide salt of a
cyclic nitrogen base such as, for exam_ple,alu
minum chloride in admixture with pyridine 'hy
drogenfchlo'ride.
_
'
'
i
compounds, the 'aromaticnucleus of which'con
tains long ‘side ‘chains, is'ge'nerally not" preferred.
Thus of the-suitablehydrogen-donora'thé arc“
desirable.
'
"
'
‘I
e
‘
While no attempt is made to enumerate or ‘clas
sify-zall of the aromatic ‘hydrogen-donors which
may suitablybe used within the scope of the in
'
fThe isomerization is preferably executed in the
presence of a hydrogenjhalildepromoter, such as,
for example, hydrogen chloride, The amount of 50 vention, the following are cited ‘as speci?c ex
amples. Suitable phenolic-type hydrogen-donors
hydrogen chloride used may vary widely in ac
comprise, hydroquinone, pyrogallol, phloroglu
cordance with operating conditions‘, In. general
cinol; catechol, resorcinol, and the like, as well
an amount of hydrogen chloride/equal to from
as their homologues and analogues and suitable ‘
about'0.3%’ to about 40%‘ of the hydrocarbon
charge is found to be su?icient. Higher propor +55 substitution "products vas " chlorhydroquinone, 'di
chlorhydroquinon'efetc.1‘Suitable aromatic hy
tions of the hydrogen chloride may, however, be
drogen-‘donors comprising the amino group in-,
used. The isomerization reaction may be exe
cuted in either thervapor or liquid phase.’ Isom- ‘ clude'amino ‘phenol, 2-4 'diam'iriophenolQ para
methyl aminophenol, 2-aniino-5-hydroxy toluene,
erization of the more stable hydrocarbons such as,
for example, the'conversion of butanev to isobu
tane is generally preferably carried out in the
vapor phase in the presence of a supported cata
to
lyst. ‘ Isomerization of the more readily degraded
benzyl-para-aminophenol,aniline; '
'
'
"
The amounts in which'the hydrogen-donor is
to be introduced into the ‘reaction zonemay vary
considerably-within the scope ‘of the invention,
depending upon the nature "or the material’ treat
hydrocarbons having at least ?ve carbon atoms to 65 ed, the speci?cvcatalyst used,‘ and ‘the ‘operating
hydrocarbons‘ such as the open chain para?inic , .
pentane ‘ and the
"conditions. ' A signal'a’dvantage of the invention
branched chain hydrocarbons is generally exe
‘cuted'inthe liquid phase. The temperature of
materials which generally need- be ‘used to‘e'ffect
the
molecule, ' particularly
operation is generally dependent upon the par
ticular catalyst used and the nature of the hydro
carbon, treated. When isomerizing' more stable
hydrocarbons in the vapor phase, temperatures in
the range of from about 50° 'CLto about 200° ‘C. /
resides, however, in the- small amount of these
substantial reduction of'hydrocarbon‘ decomposii
tion-‘under the ‘prevailing 'vi'someriza'tion condi
'ftions; Addition of the“hydrogen-donor' in an
amount equivalent toy from‘ about'0.001% to about
1% is'gene'rally found to ‘be suitable. "1 It is to'be
understood, - however,""atliat'”the invention‘ is '_not
and'preferably from about 80° C.‘ to‘ about l50f‘1C.
are-generally’ employed. Isomerization ‘of the 75 necessarily‘limited to the‘intro'duction of any par
2,404,436
5
.
ticular proportion of the hydrogen-donor to the
reaction zone and substantially larger propor
tions than those speci?ed above may be used.
The hydrogen-donor may be added directly to
the charge or may be introduced'separately into
the reaction zone.
the preparation‘ of aviation fuels from methyl
pentane.
The ability of the aromatic compounds within
the above-de?ned class to inhibit hydrocarbon
decomposition in the presence of aluminum hal
ide catalysts has been attributed to the liberation
of nascent hydrogen under the condition of exe
cution of the isomerization reaction. Though a
uniformly identifying characteristic of the aro
matic compounds suitable as hydrogen-donors in
the process of the invention is their ability to
liberate hydrogen under isomerization conditions
in the presence of Friedel-Crafts type catalysts,
the invention is in no wise to be limited by any
15 theory advanced herein for the purpose of set
ting forth more clearly and more fully the nature
It may be added as such or
in any other form comprising, for example, its
solution or suspension in, or its admixture with
a suitable medium. The addition may be made
continuously or intermittently during the course
of the operation.
7
Of the hydrogen-donors mentioned above the
phenols, containing more than one hydroxyl group
attached to the aromatic nuclei, such'as, for ex
ample, hydroquinone, are somewhat preferred.
The extent to which the ei’?ciency of the isomer
ization process is improved by the presence of the
aromatic hydrogen-donors is exempli?ed by the
of the invention.
following example:
~
‘
We claim as our invention:
1. A process for isomerizing methyl pentane to
20 dimethyl butane ‘ which comprises contacting
Example
methyl pentane in admixture with hydrogen hal
2-methy1 pentane was treated with a molten
ide at isomerizing conditions with a molten mix
ture of halide salts containing an uncombined
aluminum halide in the absence of any added
mixture comprising 88.1% SbCls, 10.8% AlCla, and
1.1% NaCl at a temperature of 65° C. with a con
tact time of 15 minutes and a ratio of catalyst
to hydrocarbon of 1 to 5 by volume. Hydrogen 25 free metal in a reaction zone and avoiding sub
stantial hydrocarbon decomposition by introduc
ing into said reaction zone small proportions, not
substantially in excess of about 1% by weight of
the hydrocarbon feed, of uncombined hydro
‘ chloride in the amount of 36.5% by weight of the
hydrocarbon charge was introduced into the re
action zone. Analysis of the product obtained is
shown in table A. The experiment was repeated
'
-'
under substantially identical conditions with the 30 quinone.
2.
A
process
for
isomerizing
methyl
pentane
to
exception that a trace of hydroquinone (substan~
dimethyl butane which comprises contacting
tially less than 0.1%) was added to the 2-methyl
methyl pentane in admixture with hydrogen hal
pentane charged. Analysis of the product ob
ide at isomerizing conditions with a catalyst com
tained in the latter experiment is shown in
35 prising uncombined aluminum halide in the ab
table B.
sence of any added free metal in a reaction zone
-
Per cent isopentanc.-.
A
28
sition by introducing into said reaction zone small
proportions, not substantially in excess of about
3
25
Per cent neohexane____
l0 '
Per cent hexanes and heavier ____________________________ .. 37
and avoiding substantial hydrocarbon decompo
B
1 40
42
54
1% by weight of the hydrocarbon charge, of an
uncombined hydroquinone.
-
3. In a process for isomerizing saturatedhydro
carbons wherein an isomerizable saturated hydro
47% of the material shown as hexanes and
heavier in table B consisted of unconverted 45 carbon having at least ?ve carbon atoms to the
molecule is contacted at isomerizing conditions
methyl pentane.
'
'
in admixture with a promoting amount of hydro
It is apparent from the foregoing example that
genchloride with uncombined aluminum chloride
the introduction of only traces of the aromatic
in the absence of any added free metal in a
hydrogen-donors into the reaction zone wherein
the readily degraded methyl pentane was being 50 .reaction zone, the improvement which comprises
introducing into said reaction zone small propor
converted to dimethyl butane reduced the amount
tions, not substantially in excess of about 1% by
of hydrocarbon decomposition products from
weight of the hydrocarbon charge, of uncombined
about 53 per cent to about 4 per cent. It is fur
hydroquinone,
thereby avoiding any substantial
ther to be noticed that the amount of the highly
hydrocarbon
decomposition.
desirable neo-hexane (2-2-dimethyl butane) in 55
4. In a process for isomerizing normal and
the product obtained was more than quadrupled.
branched chain saturated hydrocarbons having
To obtain anywhere near such a reductionin
at least ?ve carbon atoms to the molecule to
hydrocarbon decomposition with the aid of added
branched and more highly branched chain sat
hydrogen requires the use of a partial pressure of
urated hydrocarbons respectively wherein said
this gas of at least 300 pounds.
This necessi- ~
tates the use of expensive high-pressure appa
ratus and entails the increased cost and di?i
60 hydrocarbons are contacted at isomerizing con
culties involved in maintaining and recirculating
this gas within the system. It is thus readily
apparent that the use of the hydrocarbon de
ditions in admixture with a promoting amount
of a hydrogen halide with a catalyst comprising
an uncombined aluminum halide in the/absence
of any added free metal in a reaction zone, the
65
improvement. which comprises introducing into
invention permits the realization of substantial‘
savings in the cost of apparatus and operation.
The particular advantages inherent in the inven
tion are amply displayed in the ability to produce 70
more e?iciently and cheaply than heretofore d1
stantially in excess of about 1% by weight of
the hydrocarbon charge, of uncombined hydro
"composition ‘inhibitors in accordance with the ,
methyl butane (neohexane) ‘so highly desired in
said reaction zone a controlled amount, not sub
quinone, thereby avoiding any substantial hydro
carbon decomposition.
CHESTER C. CRAWFORD.
DAVID LOUIS 'YABROFF.
Документ
Категория
Без категории
Просмотров
0
Размер файла
568 Кб
Теги
1/--страниц
Пожаловаться на содержимое документа