Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
2112519
CASE 3622
"CATALYTIC PROCESS FOR PRODUCING SYNTHESIS GAS"
The present invention re~ates to the production
of synthesis gas ("syngas") by starting from methane,
oxygen and, possibily, carbon dioxlde and ~ater, ~hich
process is carried out over a plurality of catalytic
beds arranged in cascade and feeding the feedstock to
the process as a plurality of subdivided streams fed
upstream from each catalytic bed.
The synthesis gas, also referred to as "syngas"
is prevailingly constituted by a gas mixture of CO and
H2. Producing the syngas mixture is presently the key
passage in the technology of production of fuels for
motor vehicles by means of Fischer-Tropsch synthesis,
in the technology of production of methanol and higher
alcohols, and in ammonia synthesis. The investment
costs and energy consumptions for operating the
production units for syngas are estimated to be
approximately 60% of total costs of the above listed
processes.
Syngas is presently produced by means of steam
reforming or auto thermal reforming or processes of
partial, non-catalytic, oxidation of hydrocarbons. The
reactions which constitute the base of these
conversions are the following~
:
CnHo + n/2 02 ~~~> n CO + m/2 H2 Cl]
CnH~ + n H20 -~-> n CO + (m + n/2) H2 C2]
Cn H~ + n C02 ~~~> 2n CO + m/2 H2 C3]
~: Cn H~ ~~~> Cn + m/2 H2 C4]
2CO ---> C ~ C02 C5]
C0 + H20 -~~> H2 + CO2 C6~
-- 2. 2 1 1 2 5 1 9 ;
~ . ~
. ~.....
In greater detail, the steam reforming processes
catalytically convert hydrocarbonslsteam mixtures
tH20:C=2.5 - 3.5~, yielding C0/H2 mixtures ~ith an
H2/C0 ratio ~hich typically is of round 3. The
chemical reactions involved in the process are ~2~
. . , ~
C4-5] and C 6
The H20/C ratio in the reactant mixture is both
determined by the temperature and pressure conditions
under which the reactions are carried out, and by the
need of inhibiting the coal formation reactions C4-5]
The commonly used catalysts in these processes are
based on Ni supported on Al, Mg, Si oxides. These
carriers display high characteristics of heat
stability and mechanical strength. The reactions are
carried out inside tubular reactors installed inside a
combustion chamber. The pressures inside the tubes are
typically comprised within the range of from 1 to 5
MPa, and the gas temperature at tube outlets typically
is of round 8500C (reference is made, for ;~nstance~ ~o
"Catalysis Science and Technology"; Vol. 5 (1984),
chapter 1, J.R. Rostrup-Nielsen).
The non-catalytic partial oxidation processes are
less ~idely used and are employed in order to convert
mixtures of oxygen, hydrocarbons, steam and water into
syngas ~ith Hz/C0 ratios of typically round 2. The
chemistry of the process can be represented by the
e~uations C1], C4]-C6]. The facilities installed
heretofore by Texaco and Shell (see Hydrocarbon
-
trocessing; April 1990, page 9q) use adiabatic
reactors inside ~hich the reactions are initiated at
- . . ~
.: - : - ~
: ~ . .: . :.
."~ , ".~,,
3 2112519
reactors inlet by means of a burner in ~hich total
hydrocarbon combustion reactions ~7~ take place. These
reactions produce large heat, steam and C02 amounts.
Heat causes reactions of cracking of unburnt
S hydrocarbons and favours the steam C2] and C02 C3]
reforming reactions.
The operating temperatures are typically
comprised within the range of from 1250 to 1500C, and
the pressure is allowed to range from 3 to 12 MPa.
The processes of autothermal reforming are
carried out inside adiabatic reactors to which
mixtures of hydrocarbons, oxygen and steam are fed. In
a first reaction zone, the reactions are initiated of
total combustion of hydrocarbons, represented by the
equation:
CnH~ + (n + m/2) 02 ~~~> n C02 + m/2 H20 [7]
In a second zone inside a catalytic bed, the
steam C2] and C 02 C3] reforming reactions take place.
In the catalytic bed, nickel-based catalysts are used,
the characteristics of which are analogous to those as
described above for steam reforming processes. In the
autothermal reforming, mixtures of H2/C0 having values
ranging from those of steam reforming processes to those of non~
catalytic partial oxidation, are obtained.
~ - The temperature of
; the gas streams at reactor outlets is typically
comprised within the range of from 950 to 10000C, but
~;~ the temperature of the zone in which the burner is
installed is considerably higher. The pressure inside
the reactors is comprised within the range of from 2
~' `:
4 2112~19 :
to 4 MPa. - ~
:
One from the main drawbacks ~hich limit the
possibilities of technological innovation in the
definition of new catalyt;c reactors and ne~ processes
routes for syngas production and use is determined by
the coal formation reactions C4]-C5~. Coal formation
is not tolerated in the catalytic processes for syngas
production and is prevented from occurring by using
reactants mixtures containing steam and/or oxygen.
According to the syngas production processes and the
operating conditions, therefore, restraints exist as
to the composition of the reactant mixture and, in
particular, as to its steam and/or oxygen contents;
such restraints are generally expressed in terms of
. . .
15 H20/C and Oz/C ratios. -;- ;`~
Extending the threshold values of composition of
: . ~.
the reactant mixture, would make it possible
innovative solutions to be designed for syngas
production processes, because one might state tha~ the
characteristics of the reactors and of the process
schemes in syngas production facilities are the result
of complex ;nteractions between the chemical
properties of the catalysts and mechanical constraints
to the characteristics of the materials used in the
~ ~ .,i.
25 reactors. ;
In Italian patent application No. 19,162 A/90,
fiLed on January 26th, 1990, to the same Applicant's ` ` `
name, disclosed is a process for syngas production by ~ ; d
starting from carbon dioxide and light hydrocarbons,
in particular methane, over a supported catalyst based
.
5 2112519 ~
~ " .,
on a metal from pLatinum group. Furthermore, in
Italian paten~ application No. 21,326 Al90, filed on
August 29th, 1990, to same Applicant's name, disclosed
is a process for syngas production by means of a first
step, of non-catalytic combustion of hydrocarbons with
oxygen, followed by a second step, of reforming, in
which the oxidation products from the first step are
brought into contact with a further amount of
hydrocarbons, in the presence of a supported cataLyst
of a metal from platinum group.
The present Applicant found now, according to the
present invention, that the use of noble metal
catalysts considerably reduces the width of the
regions inside which the coal formation reaction takes
place and therefore makes it possible reaction
mixtures with low H20/C (e.g., lower than 0.5) and
02/C ratios (e.g., lower than 0.5) to be used without
that the coal formation reaction are initiated.
Such a finding makes it possible said catalysts
to be used in a process for syngas production in a
reaction system consisting of a plurality of adiabatic
catalytic beds arranged in cascade, in which a
differentiated feed of the reactant mixture is
~ . .
preferably provided, and in which the composition of
: ~ :
said mixture at the inlet to said catalytic beds may
even have values of H20/C and 02 /C ratios, which are
lower than 0.5 and 0.5, respectively. Furthermore, a
catalytic process which displays such characteristics -~
makes it possible syngas mixtures to be obtained
30 withour requiring that at its inlet a burner is ~;~
' ', ~
6- 2 1 1 2 5 1 9
instaLled, because the combustion reactions are
cataLyticaLLy initiated at Lou temperatures.
More particuLarly, the process for syngas
production, carried out on a pluraLity of adiabatic
cataLytic beds in cascade, according to the present
invention, enables the foLlowing advantageous effects
to be accompLished~
-- reduction of temperature gradients and also of the
highest temperature values inside said catalytic
;,.,: - ~
beds, with consequent lower thermal stresses being
applied to the materiaLs; in that ~ay, traditional
building materiaLs can be used, with consequent
savings in investment costs;
-- possibility of directLy obtaining, at the outlet
from the catalytic partial oxidation reactor,
syngas with H2/C0 ratios comprised within the range
of from 0.9 to 3, without that the adjustment of
the vaLue of such a ratio requires that a further
reactor for water gas shift (WGS) reactions ~6] is
used;
-- possibiLity of avoiding using a burner at reactor
inlet, with consequent saving in reactor investment
costs;
-- improvement of heat efficiency of syngas production
process, both as compared to the commerciaL
processes of non-cataLyzed partiaL oxidation
-~: ~ . . ~ . .. :
processes, and as compared to autothermaL reforming
processes; such an improvement is made possibLe
because the configuration of the reactor makes it
possibLe the heat recovery rates to ~e optimized,
~: _.. _~,._.,.~_., _. ,. _, . _. ,, . _, ,, ~.. ., .. . _ . .. _ . ,.. ..... ... ,. _.__. ~___ ._~.. ,.. ~ .. _ .. _. __.. _ ,._ .. _. __ .. _~_..
_~ .. _._.. _ . _ .. .... _ : . :
7 211251~
"~
by preventing the unnecessary~ extremely high
temperatures ~hich occur inside the interior of the
reactors (in particular at inlet regions) used in
the exisiting processes;
-- possibility of kinetically controlLing the coal
generation reactions and, therefore, of reducing
the vaLues of HzO/C (steam mols/carbon mols) and
02 /C (oxygen mols/carbon mols) ratios in the
reactant mixture;
-- possibility of optimizing the process conditions,
with in each layer the conditions of maximaL
reaction speed being reached, with the catalyst
amount being consequently decreased (decreasing the
catalyst amount is a determinative factor when
noble metal-based catalytic system are used).
In accordance therewith, the present invention
relates to a catalytic process for preparing synthesis
gas by starting from methane, oxygen and, possibily,
carbon dioxide and water, characterized in that~
2û -- the catalyst used is a noble metal catalyst
supported on a solid carrier, arranged as a~ ~L
plurality of fixed catalytic beds in cascade to `~
each other; ~ -
-- the gas feed stream contains methane, oxygen,
carbon dioxide and water in the following molar
proportions: r~
methane 1.0;
oxygen from û.2 to 1.0;
carbon dioxide from 0 to 3.û;
wate~ from 0 to 3.0; and
, .::
2112519 ;~;
-- the process is carried out under adiabatic
conditions;
by feeding the gas reactant stream upstream from
the first catalytic bed and removing heat, by heat
exchange between the catalytic beds arranged in
cascade, or ~ ~ -
by feeding the gas reactant stream partially
upstream from the first catalytic bed and partially,
as a cold stream, between the catalytic beds arranged
in cascade, with said partial feeds being of same
composition, or having different compositions from
each other, with the proviso that methane is at least
partially fed to the first catalytic bed and oxygen is
subdivided between all of the catalytic beds.
The catalysts useful for the process according to ~ ~ -
the present invention are constituted by one or more
metals from platinum group, selected from Rh, Ru, Ir,
Pt and Pd, supported on a carrier selected from
aluminum, magnesium, zirconium, silicon, cerium and/or
lanthanum oxides and/or spinels.
Said carrier can also be provided with surface-
grafted silica moieties, and suitable processes for
preparing such carriers with surface-grafted silica
moieties are reported in the experimental examples
supplied in the following in the present application,
in the above mentioned Italian patent applications and
in United Kingdom patent application ~B 2,240,284.
Preferred carriers for such catalysts are alumina
and/or magnesium oxide, possibiLy provided with
surface-grafted silica moieties.
9 2112519 -: ~
The catalysts of the first cataLytic bed contain
rhodium in association with platinum or palladium, and
the catalysts of the subsequent catalytic beds
preferably contain two metals selected from rhodium,
5 ruthenium and iridium, with the overall percent ~t
contents of noble metals in the supported catalyst
being comprised ~ithin the range of from û.05 to 1.5X
by weight, and preferably of from 0.1 to 1% by weight. ;~
In order to be used as a stationary catalytic
10 bed, the catalysts will preferably be in granular
form, with particle size comprised within the range of
from 1 to 20 mm.
The catalytic beds used will be at least two,
with their maximal number, dictated by practical
15 reasons, being of four or five. Preferably, the
process will be carried out with either two or three
catalytic beds in series to each other. These
catalytic beds can be arranged inside a plurality of
reactors arranged in series to each other, but
20 preferably, one single reactor containing a plurality ;-~
of catalytic beds will be used. -~
According to the present invention, to the
catalytic beds a gas stream is fed ~hich contain
methane and oxygen, and possibly also carbon dioxide
25 and/or water, preferably in the following molar ~-
proportions:
methane 1.0; ; ~-~
oxygen 0.4-0.6;
carbon dioxide 0-1.0; and
30 water û-1Ø
'. . :,'':':~
-,
1o. ~:
2 ~ 1 2 5 1 9
As said hereinabove, the process is carried out ;
under adiabatic conditions by feeding the gas reactant
stream totaLly upstream from the first bed and
removing heat, by heat exchange, from points between ` ~ -
S the catalytic beds arranged in cascade.
According to a preferred embodiment, the process
is carried out under adiabatic conditions by feeding - ~`
the gas reactant stream partially upstream from the ~-
first catalytic bed and partially, as a coLd stream,
10 between the catalytic beds arranged in cascade. The ` -;
gas streams fed to the individual catalytic beds can ~ -
have the same composition, or compositions different ; ;
from one another. In the latter case, methane will be ~ ;3"'.
at least partially fed to the first catalytic bed and
15 the oxygen feed stream will suitably be subdivided --
,: ~- :-
between all catalytic beds.
In any case, by operating according to the
, . ,.,..:, .
present invention, synthesis gas is obtained by the
effect of partial methane oxidation, and, possibly, -~
also owing to reforming phenomena, as a function of
the fed reactants. ~ -~
According to an embodiment of the present
;invention, to the first catalytic bed a gas stream is ~-
fed which contains methane, oxygen, carbon dioxide and
steam, and to the subsequent catalytic beds an oxygen
stream is fed. Preferably, the process will be carried
out with a moLar ratio of methane, carbon dioxide and ;~
water fed to the first catalytic bed, of 1:û.5-1:0.3
1, and with a total oxygen amount of 0.4-0.6 mols per
30 each methane mol, fed as subdivided streams to each of - -
1 1 .
2112519 ~-~
ir
the several caeaLytic beds.
According to another embodiment, to the first
catalytic bed a gas stream is fed which contains
methane and oxygen, and to the subsequent catalytic
beds a mixture is fed which contains methane, oxygen
and carbon dioxide. Preferably, the process will be
carried out with a molar ratio of methane to oxygen
fed to the catalytic beds of the order of 1:0.4, and
with an amount of carbon dioxide of the order of 0.4
mols per each mol of methane.
According to a further embodiment, to the first
catalytic bed, and to the subsequent ones, a gas
stream is fed which contains methane, oxygen and
carbon dioxide. The molar ratios of these reactants to
each other will preferably be of the order of
1:0.6:0.7-0.8.
According to a further embodiment, to the first
catalytic bed a gas stream is fed which contains
methane, oxygen and carbon dioxide, and to the
Z0 subsequent catalytic bed an oxygen stream will be fed.
The process will preferably be carried out with a
molar ratio of methane to carbon dioxide fed to the
first catalytic bed of 1:0.3-0.6, and with a total
oxygen amount of 0.5-0.6 mol per each mol of methane,
subdivided to the various catalytic beds.
It should be observed that according to the
present disclosure, the term "oxygen" is understood to
mean pure or substantially pure oxygen, or oxygen
mixed with an inert gas, such as nitrogen, e.g., air.
In general, the process will be carried out with
' Z 2 1 1 2 ~ 1 9
inlet temperatures to the tirst bed of the order of
300-4000C and ~ith outlet temperatures from said first
bed, of the order of 700-8700C. The inLet temperatures
to the beds downstream from the first bed will be of
the order of 450-7300C, and the outlet temperatures
will be of the order of 770-8500C. The cooling bet~een
two adjacent beds will cause a decrease in temperature
of from 10OC, up to as high values as 420OC and will
normally be of the order of 120-1700C. The pressures
under which the process is carried out may generally
be comprised within the range of from 0.1 to 10 MPa.
The space velocities, under the reaction conditions,
may generally be comprised within the range of from
1,000 to 50,0ûO h-l and will normally be of the order
of 5,000-20,000 h-~
8y operating under these conditions, the mixture
recovered at the outlet from the last catalytic bed,
will contain hydrogen and carbon monoxide in a molar
ratio to each other comprised within the range of from
20 about 0.9 to about 3 and normally of from about 1 to
about 2.3.
It should be observed that in the case of
exothermic reactions like the reaction of partial
hydrocarbon oxidation C1], the expected reactant
25 conversion rates as calculated by means of equilibrium
thermodynamic computations, vary as a function of
temperature, according to the trend schematically
sho~n in Figure 1. On the other hand it is known (O.
Levenspiel, "Chemical Reaction Engineering", John Wiley and Sons, .
- 2 1 1 2 5 ~ 9
Inc., New York London) that the conversion rates, the
reaction temperature and the reaction speed are
m~tuaLly linked parameters. For exothermic reversible
reaction (like the partial oxidation react;on C1
which are catalyzed in a "Plug-Flow" reactor, a
temperature increase kinetically favours the
transformation of the reactants into the reaction
products, but, opposite to this trend, the temperature
increase decreases the max;mal conversion rate which
can be obtained. In these cases, the optimal
temperature variation can be obtained in reactors with
a plurality of adiabatic layers with intermediate
coolings induced by means of heat exchanges with heat
recovery, or by means of the introduction of "cold"
gas streams of reactants between the layers~ In Figure
1, "isospeed" curves are reported (i.e., curves along
which the reaction speed remains constant with varying
values of temperature and of reactants conversion),
according to the typical trend of exothermic
processes. The peak points of isospeed lines determine
pairs of values of temperature (T) and conversion
(Xa). The line which connects all of these points with
each other (i.e., the line which makes it possible the
maximal reaction speed values to be obtained with
varying temperature) describes the optimal temperature
progression for a Plug-Flow reactor in which an
exothermic chemical process is being carried out.
~ Similar considerations may be made in the case of;~ endothermic processes. Such a curve can be
e-perimentally followed by means of a catalytic,
.,
t~
`
14. 2112519
: .- ~ . ~. ..
adiabatic-layer reactor provided with a plurality of
reaction zones separated by temperature adjustment
zones, as in the case of the process disclosed herein.
:~- : . ~, ~;
The following experimental examples are reported
in order to better illustrate the present invention.
E_3m~
A laboratory reactor is used wh;ch is provided
w;th two reaction zones, to which two different
catalysts are charged.
The reactor was so accomplished as to make it
possible the reactants tmixtures of methane, oxygen,
steam and carbon dioxide) to be fed both to the
reactor head, directly to the first catalytic bed
(first adiabatic layer), and in the separation zone
between both catalytic beds (i.e., between the first
and the second adiabatic layers).
The reactor is constituted by an alumina tube
with an extremely low porosity and displaying high
heat resistance and mechanical strength
characteristics. The alumina tube was fitted into a
steel jacket. Around the steel tube, in the region of
both reaction zones, two resistors are installed, the
function of ~hich is of compensating for the heat
losses caused by the non-perfect adiabatic character
of the reactor (this is a drawback which is impossible
to remove in such a type of testing in smaL~-size
laboratory reactors). Inside the alumina tube, there
is fitted a thermocouple well. The steel sheath of the
thermocouple ~ell was coated with a thin gold layer in
order to prevent coal from being formed on its
- '5 2112~19
., . ~ .
surface. The temperatures inside both adiabatic layers ~
were measured with the aid of two thermocoupLes which
could be longi~udinally moved along said beds~
The two catalysts used in these tests were
5 prepared according to the following procedures. -~
C 3 t _ l y _ _ _ _ f o r _ _ b e _ f i r s _ _ r e a _ _ i o n _ z o n _ _ ( _ i r s _ _ 3 d i a b 3 t l c
3Y__)
Into a slurry constituted by a suspension of
alpha-alumina in n-hexane, à solution of Rh4tC0)l2 and
~Pd(CsHsO2~z] in the same solvent, was added dropwise.
The solvent was then evaporated under vacuum and,
after drying, the solid powder was pressed into
. .: , ~. ~
pellets which, by crushing, yielded a granular solid -~
with maximal particle diameter comprised within the
i5 range of from 2 to 2.5 mm. The catalyst volume charged
to the first catalyt;c bed is of 5 cm3, the Rh content
in the catalyst is of 0.1% by weight, the palladium
content is of 0.5% by weight.
C3t3ly_t__or_tb___eçong_r_3Ç_1QD_Z-o-n--t--eç-o-ng-3gl3g3
l3y__)
In this case, a typical carrier for steam -
reforming catalysts was prepared, which contains ;
magnesium oxides and alumina (Mg/AL = 7l1 mol/mol),
and was obtained by means of a process comprising~
(i) co-precipitating aluminum and magnesium -`
hydroxides, by increasing the pH value of an -`-
aqueous solution of Mg(N03)z and AltN03)3.9HzO;
tii) filtering the precipitate off and washing it;
tii;) drying and calcining the precipitate at 4000C, - i
tiv) "pelletizing" the solid powder;
", ..
16. 2 1 1 2 ~ i 9
(v) treating the pellets by further calcining them
up to 1000OC and, after cooLing, crushing the
pelLets in order to obtain a granular material
with a maximal particle diameter of 2-2.5 mm.
The percent sodium level in the resulting carrier
is lower than 0.1%. The carrier was then dispersed in
a soLution of n-hexane into which a solution, in the
same solvent, of Rh4(C0)12 and Rua(C0)l2 had been
added dropwise. After evaporation and vacuum drying, a
granular material was obtained which contained 0.1% by
weight of Rh and 0.5% by weight of Ru. The catalyst
volume charged to the second catalytic bed is of 5
cm~
Prior to the reaction, the catalysts were treated
at the temperature of 5000C, with H2/N2 streams
containing increasing hydrogen levels. Then, to the
inlet to the first catalytic bed a stream was fed
which contained CH~:COz :02 :H20 in molar ratios of
1:1:0.5:0.3. The total flowrate of feedstock fed to
the first catalytic bed was of 50 Nl/hour, the gas
stream inlet temperature was kept at 3000C, the inner
reactor pressure was kept at 10 atm. Before entering
the second adiabatic layer, the leaving stream from
the first catalytic bed was mixed with a second stream
of oxygen pre-heated at 3000C, fed at a flowrate of
2.3 Nl/hour.
In Table 1, the main features of this experiment
are reported.
_A~jLE~
I-t-3-dl3-b3-i--l3
i: :
~ 17
2112~19
Catalyst~
-- composition: Rh (0,1%) + Pt (0~5X) on Al20
-- amount: S cc
Inlet composition:
-- CH4:CO2 02:H20 = 1:1:0.5:0.3 tvolume ratios)
. , ~ ....
Feed flowrate:
-- CH4 = 17.90 Nl/hour ;
-- COz = 17.90 Nl/hour
~- 02 = 8 70 Nl/hour ~-
-- H20 = 5 30 Nl/hour
-- total = 50 00 NL/hour
Temperatures P
-- ;nlet = 3000C ```~
-- outlet = 7450C
II-g--gi_ba_
Catalyst: ! -
-- composition Rh (0 1%)+Ru (0.5%) on MgAlOx ;
Inlet composition: ~ i
-- gas product from the Ist layer + added 02
-- 02 feed flowrate: Z.30 Nl/hour
Temperatures: `
-- inlet = 7300C
-- outlet = 8100C
_om eo i tioo_3t_rea__or_outl__:
% by mol Mols/hour
~;~ -- CH~ 5.20 0.16 -,~
-- CO2 23.46 0.73
-- HzO 21.59 0.67 `~
02 --- ---
30-- H2 27.04 0.84
~ 18. 2 1 1 2 ~ 1 9
-- C0 22.68 0.71
Molar ratio of H2:C0 at reactor outlet: 1.18:1. ~ ~
Ex_mel__2 '.:5~ ,.''
The same experimental devices and the same catalysts
as disclosed ;n experiment 1 were used, by feeding to
the inlet to the first catalytic bed a reactant stream
with a total flo~rate of 50 Nl/hour and having the;~
composition CH4:C02:02:H20 = 1:0.5:0.4:1 and feeding,
upstream from the second catalytic bed, a stream of~~
oxygen pre-heated at 3000C, with a flo~rate of 3
Nl/hour. -~
The main features of this second experiment are
reported in Table 2
_ABLE__
I_t_3g13g3_ic_l3yer
Catalyst:
-- composition: Rh (0,1%) ~ Pt (û,5X.) on Al20
-- amount: 5 cc
Inlet composition:
ZO -- CH4 :C02 :02 :H20 = 1:0.5:0~4:1 (volume ratios)
Feed flo~rate:
-- CHg = 17.20 Nl/hour
-- C02 = 8.60 Nl/hour
-- 02 = 7.00 Nl/hour ~
-- H20 = 17 20 Nl/hour - --
-- total = 50.00 NL/hour
Temperatures:
-- inlet = 300OC
~: : ,
-- outlet = 705OC
II_g__gi_b__i~ y_r
-
9. 2112519
Catalyst~
-- composition: Rh (O.lY.) + Ru (0.5%) on MgAlOY
-- amount: 3 cc ~".,.','!:,.'"
Inlet composition:
-- gas product from the Ist layer + added 02
-- Oz feed flowrate: 3.00 Nl/hour -~
Temperatures:
-- inlet = 6900C -~
-- outlet = 8050C
__mp__i_i_n____________outl_t:
% by mol Mols/hour
-- CH4 5.10 0.16
C02 16.60 0.52 -~
-- H20 29.27 0.92
1502
-- Hz 34.11 1.07
C0 14.93 0.47
Molar ratio of H2:C0 at reactor outlet: 2.28:1.
___mpl__3
In this experiment, the same exerimental devices
as disclosed in Examples 1 and 2 were used, but
catalysts were used which contained nobLe metals
deposited on alumina with surface-grafted silica
moieties ar,d magnesium carriers.
_a _ly_t_for__b___ir___reac_ion_z_n__( f i _ _ _ a g i abati-
A commercial alumina sypplied by AKI0, having a
surface area of approximately of 200 m2/g was ;~
suspended, with stirring, in a tetraethyl silicate
30 (TES) solution. The temperature was kept comprised `- -
20. 2 1 1 2 5 1 9
within the range of from 80 to 900C~ Under these
conditions, a trans-esterification reaction took place
which is represented by equation C8~ and led to the
development of ethanol in gas form~
Si(OC2Hs)4 ~ Al-OH ---> Al-O-SitOC2Hs)3 + C2Hs-OH
A gas stream of anhydrous nitrogen ~as fed to the
reaction environment. Gas-chromatographic analyses on
the leaving gas showed that ethanol had been formed.
The reaction was regarded as concluded when in the gas
stream the presence of ethanol was no longer
detectable. At this point, the temperature was
increased up to 180C, in order to distil off any
unreacted TES. The unreacted ethoxy groups bonded to
silicon atoms which, in their turn, were anchored to
the surface, were then hydrolized by feedir,g, at
2000C, a nitrogen stream saturated with steam. The so
obtained solid material was heated up to 8000C and was
kept at this temperature during 10 hours. After
cooling, the material was used as a carrier, onto
which rhodium and platinum were deposited. The
finished catalyst contained 0.1X of rhodium and 0.5%
by weight of platinum.
Ca_3ly___f___t_e_s___nd___3__i_ _zQ___lse_ond_3gi3b3tic - ~. ;
l3ye_)
The surface silica-grafting process as disclosed
above was repeated on a carrier of commercial
magnesium oxide having a surface area of 150 m2lg.
Onto this magnesium oxide with surface-grafted silica
moieties obtained by means of this procedure, 0.1X by
weight of Rh and 0.5% by ~eight of Ru were then
, .
21. 2112~19 ~
deposited according to the same procedure as disclosed ; ~ ;
;n Example 1. `;;
The catalytic test was carried out according to -
the same procedure as disclosed in Examples 1 and 2.
After a reducing treatment, a stream containing
CH4:C02:02:H20 in molar ratios of 1.û:1.0:û.4:1.0 was
fed to the inlet to the first catalytic bed. Before
entering the second catalytic bed, the stream leaving
from the first catlytic bed was admixed with an oxygen ;- -~ r
10 stream fed at a flowrate of 1.8 Nl/hour. ` - i~
The main features of this experiment are ;-
disclosed in Table 3
TABLg_3 , `
___3gl3b3ti__l3yer
Catalyst~
-- composition: Rh (0,1%) ~ Pt (0,5%) on silica~
grafted alumina ?~ ~-
-- amount: 5 cc
Inlet composition: ;
~ 2û -- CH4:C02:02:H20 = 1.0:1.0:0.4:1.û tvolume ratios)
;~ Feed flowrate:
-- CH4 = 14.70 Nlthour
-- C02 = 14.70 Nl/hour
-- 02 = 5.90 Nl/hour
25 -- H20 = 14.70 Nl/hour
' -- total = S0.00 Nl/hour
i` ` Temperatures: ~ -
-- inlet = 300~C
outlet 698 C ; `
II0d_adi_b__i _l_ye~
~ 22. 2112~19 ;~
Catalyst~
-- composition: Rh (0.1%) + Ru tO.5X) on silica~
grafted magnesium oxide
-- amount: 3 ~c ~ .t '
Inlet composition~
-- gas product from the Ist layer + added 02
-- 02 feed flowrate: 1.47 Nl/hour ~ r~r
Temperatures -
-- inlet = 6850C
-- outlet = 790
_om eo _1tion_at_ reactor_outl_t~
% by mol Mols/hour
-- CH4 4.41 0.13
-- CO2 21 11 0.64
15 -- H20 26 83 0 81
~~ 02 ___ ___
-- H2 29.65 0.90
-- CO 18.01 0.55
Molar ratio of H2:CO at reactor outlet: 1.64:1. ;~
EX3-mel-e-4
In this experiment, to the first catalytic bed, a
volume of S cm3 was charged of a catalyst containing ;~
0.1'~ by weight of Rh and O.SX by ~eight of Pd. The
metals were deposited according to the same procedure
as disclosed in Example 1, on a carrier constituted by
magnesium and aluminum oxides (Mg:Al = 7:1 mol/mol),
using a solution containing Rh4(C0)12 and
CPd(CsHsO2)2] in a hydrocarbon solvent.
To the second catalytic bed, a volume of 4 cm3
was then charged of a catalyst containing O.SX by
23. 2~ 12~19
. . " . .~ - .. ...
weight of Ru and O.5Y by weight of Ir, deposited on
magnesium and aluminum mixed oxide. The deposition of -
these metals onto the carr;er ~as accomplished by ~-~
adding, dropwise, a solution of Ir4(CO)l2 and --
S Ru3~CO)12 in a hydrocarbon soLvent, to a suspension of ~ ~H
the carrier in the same solvent, as discLosed in
Example 1.
After a treatment in a Hz-N2 stream at 500oC, a
stream of CH4 and 02 (CH4:02 = 60:25 by vol/vol) was t .
10 added to the first catalytic bed, and upstream from
the second catalytic bed, a stream of CH4, 2 and C02 ~-.. `
(CH4:02 :C02 = 40:25:40 by vol/vol) was admixed to the 3
gas stream from the first catalytic bed.
The main features obtained during the catalytic
15 test are reported in Table 4.
TA@LE_4
I_ _3diaba_i__l3y__
Catalyst:
-- composition: Rh (0,1Y.) + Pt (0,5%) on MgAlOx
20 -- amount: 5 cc
Inlet composition:
-- CH4:02 = 60:25 (volume ratios)
Feed flowrate:
-- CH4 = 15.78 Nl/hour
-- 02 = 6.60 Nl/hour
-- total = 22.38 N~/hour -
Temperatures:
-- inlet = 3000C
-- outlet = 745oc
IIng_3d13b3t7__~3Ye_ ~ -~
24~
2 1 1 2 ~ 1 9 ~ ~
Catalyst: i~'
-- composition: Ir (005%) + Ru (0.5%) on HgAlOy .
~ -- amount: 4 cc
Inlet composition: ~ e ;a
-- gas product from the Ist layer + CH~ + 02 + CO
added ~ ,
-- feed flourate:
-- CH~ = 10.52 Nl/hour .~
-- 02 = 6.50 Nl/hour ~ ~
10 -- CO2 = 10.50 Nl/hour
-- total = 27.52 Nl/hour -~: R
Temperatures~
-- inlet = 581C
-- outlet = 815C
_omeositicn_at re___or outlet:
% by mol Mols/hour
-- CH~ 13.95 0.43 ;~
-- CO2 14.47 0.45
-- H20 14.90 0.46 - ;~
20 -- 02 ~~~ . I--
-- Hz 32.40 1.01
I :: ~
-- CO 24.28 0.76 .~:~
Molar rat;o of H2:CO at reactor outlet: 1.33:1.
.
E x 3 m e l e _ 5
In this case, the procèss of catalytic partial ~
oxidation in an adiabatic reactor ~ith layer --
configuration ~as studied by using three Plug-Flou
reactors (uhich are referred to in the folLouing as
"R1", "R2'', "R3"), each containing one catalytic bed. :~
`~
~ ~:
,.. ~,~, . . . . . .
25.
2 1 1 2 ~ 1 9
...... ........
A m i x t u r e of CH~, 02, CO2, fed ~ith a total
gas flowrate of 149 Nl/hour (CH~ :2 :C2 = 1:0.6:0.~ by
vol/vol) was subdivided into three streams. The first
stream (flowrate 60.1 Nl/h) was fed to the inlet to
reactor R1; the second stream tflowrate 53.3 Nl/h) was
fed to a point between reactor R1 and reactor R2; the
third stream tflowrate 35.6 Nl/h) was fed to a point
between reactor R2 and reactor R3.
The temperature of the stream fed to the inlet to
the first reactor was kept at 3000C, and the inlet
temperatures to the second and third reactors were
kept at 4500C. The catalyst contained in reactor R1
(catalyst volume: 3 cm3) was composed by Rh (0.1% by
weight) and Pd (O.S~, by weight) deposited on a support
constituted by a mixed magnesium and aluminum oxide,
prepared by operating according to the same procedure
as disclosed in Example 1.
., .~ .
The catalyst contained in reactor R2 (catalyst
volume: 4 cm3) was composed by Rh tO.1% by weight) and
Ir tO~5X by weight), deposited on the same carrier of
magnesium and aluminum oxides. The catalyst was
prepared according to the same procedure as disclosed
in Examples 1 and 3. The catalyst contained in R3 was
composed by Rh tO.1'X. by weight) and Ru (0.5% by
'2 ~
weight), deposited, also in this case, onto the same ~ ~-
magnesium and aluminum oxide. The catalyst was
prepared according to the same procedures as disclosed
in Example 1.
In Table 5, the main features and the results of
-. ~
26.
2 1 1 2 5 1 9
the present experiment are reported. ~ - A
TABLE_5
I_t_3dl3b3t1--layer
Catalyst:
S -- composition: Rh (O,lY.) + Pt (0,5%) on MgAlOx
-- amount: 3 cc
Inlet composition:
-- CH4:02:CO2 = 100:60:80 (volume ratios)
Feed flowrate:
-- CH4 = 25.10 Nl/hour
-- CO2 = 20.00 Nl/hour
-- 02 = 15.00 Nl/hour
-- total = 60.10 Nl/hour ~-
Temperatures:
-- inlet = 3000C
-- outlet = 8650C
IInd_3di3b3 i__l_Y__
Catalyst~
-- composition: Rh (O.lY.)+Ir tO.5Y.) on MgAlOx , ;~i
,r"~
; 20 -- amount: 4 cc
Inlet composition: ~ --
-- gas product from the Ist layer + CH~ + 02 + C02 ;~ ~
added p ~,
-- feed flo~rate: ;n~
25 -- CH9 = 22.6 Nllhour --
-- 02 = 17.5 Nl/hour
-- CO2 = 13.2 Nl/hour
-- total = 53.3 Nl/hour -r
Temperatures:
,,
~ 30 -- inlet = 450
- ~ ~
~ 27.
2112519 ~ ~ ~
~- outlet = 8250C
I I I _ _ _ 3 g i 3 b 3 _ i e _ l 3 y - - '" ''' ~''~ `'''
Catalyst~
~- composition: Rh (0.1X) + Ru (0.5X) on ~gAlOy ~ 2
-- amount: 5 cc
Inlet composition:
-- gas product from the IInd layer + CH4 + 02 + C02` ~ ~ -
added
-- feed flowrate~
10 -- CH4 = 15.0 Nl/hour
-- 02 = 11.9 Nl/hour
-- CO2 = 8.7 Nl/hour
-- total = 35.6 Nl/hour ~ ~ .;-~
Temperatures~
-- inlet = 4500C
-- outlet = 7850C
Comeosition at reactor outlet:
___ _________________________
% by mol Mols/hour .: ~ .
-- CH4 5.74 0.54
-- CO2 18.23 ~.82
-- ~20 16.89 1.59
-- 02 --- ___
- - H 2 30.33 2.87
-- CO 28.84 2.72
~olar ratio of H2 :CO at reactor outlet: 1.055:1. `
_X_mel_____ i~
: The same experimental apparatus and the same
catalysts as disclosed in Example 5 ~ere used in
Examples 6, 7 and 8 in order to obtain a catalytic
partial oxidation process on a three-layer catalyst,
28.
2112~19 - ~
to which a feedstock consisting of methane, C02 and
oxygen was fed. In these cases, differently from the -~ -
experiment as disclosed in Example 5, the whole
amounts of CH4 and CO2 were fed to the inlet to the
first reactor R1, and the oxygen feed ~as subdivided
into three streams which were fed to the inlet o~ R1,
to an intermediate point between R1 and R2, and to an
intermediate point between R2 and R3. Examples 6, 7
and 8 are different from each other owing to the inlet
temperatures of the gas streams to the three adiabatic
layers. Different inlet temperatures to the adiabatic
Layers have determined different temperatures and
composition of the bed leaving streams.
In following Tables 6, 7 and 8, the main features
and the results obtained in Examples 6, 7 and 8 are
reported.
TABLE_6
I _ t _ 3 g i 3 b 3 _ 1 _ _ l 3 y e r
Catalyst~
20 -- composition: Rh (0,1%) + Pt (û,5%) on MgAlOx ~ ~ ;
-- amount: 4 cc
Inlet composition:
-- CH4:02:CO2 = 100:30:60 (volume ratios) '`
Feed flowrate:
-- CH4 = 68.30 Nl/hour
-- CO2 = 41.00 Nl/hour
-- 02 = 20.50 Nl/hour
-- total = 129.80 Nl/hour
Temperatures:
-- inlet = 3000C
~ ~ ,
-, ~;;
, :. . : ~ :
,, , ,~ ~
, . :
. .,-: :: . , :
;~ , . . .
29. :~
2112~9
-- outlet = 7100C
Il-ng--adi3batic layer
Catalyst~
-- composition: Rh tO.1X) + Ir tO.57.) on MgAlOx
-- amount: 4 cc
Inlet composition~
-- gas product from the Ist layer + 02 added : -
-- feed flowrate:
-- Oz = 13.6 Nl/hour
-- total = 13.6 Nl/hour
Temperatures:
-- inlet = 4500C .
-- outlet ~ 77soc
III_g_adi3batlc_layer .'; ,~ ,`.
Catalyst:
-- composition: Rh tO.1%) + Ru (0.5%) on MgAlO.y :~
-- amount: 5 cc ~
Inlet composition: ~:
-- gas product from the IInd layer + 02 added . ~.
ZO -- feed flowrate:
-- 02 = 6.8 Nl/hour !
-- total = 6.8 Nl/hour
Temperatures:
, ~: , ' .;. ~: ,.
-- inlet = 4500C
-- outlet = 7780C
__meo_itjion_ati_r_a_tior_ut~
~: X by mol Mols/hour
-- CH4 7.2 0.69
- - C 0 2 16.1 1.54
-- H20 16.6 1.59
:: .:
30. :: :
2112519 ` ~
:'.' :'''
-- 02 ~~~ ~~~
-- H2 32.6 3.1Z
-- CO 27.6 2.64 :~
Molar ratio of H2:CO at reactor outlet: 1.1818
TABLE_7
Ist__di_bati__Lay_r
Catalyst~
-- composition: Rh (0,1X) + Pt tO,5%) on MgAlOx
-- amount: 4 cc .
Inlet composition~
-- CH4:02:CO2 ~ 100:30:60 ~volume ratios)
Feed flowrate~
-- CH~ = 68.30 NL/hour
-- CO2 = 41.ûû Nl/hour :R-~
-- Oz = 20.50 Nl/hour
-- total = 129.80 Nl/hour
Temperatures~
-- inlet = 3000C
-- outlet = 715C ~ :~
IInd__di_b_ti__l_ye_
Catalyst:
-- composition: Rh (0.1%) + Ir tO.5%) on MgAlOx
-- amount: 4 cc
Inlet composition: : :~
25 -- gas product from the Ist layer + 02 added :
-- feed flo~rate-
-- 02 = 13.6 Nl/hour
~: -- total = 13.6 Nl/hour ;~ ~ -
Temperatures~
~: 30 -- inlet = 5500C ~:
: - . :.
~ ,
31' 2 II2~ I9
-- outlet = 7970C
IIIrd_3di_batic_l_y r
Catalyst: :
-- composition: Rh tO.1%) + Ru (0.5X) on MgAlOy
-- amount: 5 cc
Inlet composition~
-- gas product from the IInd layer + 02 added
-- feed flowrate:
-- Oz = 6.8 Nl/hour
-- total = 6.8 Nl/hour
Temperatures~
-- inlet = 5500C
-- outlet = 816C
COmQOsi tion_at_re__tor_outl_t: .. ~ ~ .
% by mol Mols/hour
-- CH~ 4.6 0.46 ~- -
-- CO2 16.1 1.34
-- H20 15.6 1.56
~- 02 --- ___
20 -- H2 35.9 3.60
-- CO 30.6 3.07
Molar rat;o of Hz:CO at reactor outlet: 1.172:1.
TABLE_8 .
Ist-3di3b3-l--l3y--r
'' 25 Catalyst:
-- composition: Rh (0,1%) + Pt ~0,5%) on MgAlOx ~ `
-- amount: 4 cc
Inlet composition~
-- CH4:02:CO2 = 100:30:60 (volume ratios)
30 Feed flrJwrate: ~
: '- :,: :
2 1 1 2 ~ ~ 9
-- CH4 = 68.30 Nl/hour ~. :
-- CO2 = 41.00 Nl/hour
~~ 02 = 20 . 50 Nl/hour
-- total = 129.80 Nl/hour
Temperatures~
-- inlet = 4000C
-- outlet = 7220C
ng_3glabat1~ y~
Catalyst:
- composition: Rh (0.1%) + Ir (0.5X) on MgALOx
-- amount: 4 cc
Inlet composition: .-~:.` r~x
-- gas product from the Ist layer 02 added
-- feed flo~rate:
15 -- 2 = 13.6 Nl/hour
: -- total = 13.6 Nl/hour
Temperatures:
-- inlet = 6000C
-- outlet = 812C :-
2û IlIrg-3gl3b3-~ ay-- -~
Catalyst: ; ::
-- composition: Rh (0.1~) + Ru (0.5%) on MgAlOx
-- amount: S cc
Inlet composition:
25 -- gas product from the IInd layer + 02 added :
;~ -- feed flowrate:
~~ 2 = 6.8 Nl/hour
-- total = 6.8 Nl/hour
Temperatures~
30 -- inlet = 6000C
' ~:.''
.
33. 2112519 ~:
, ~.~ .,
-- outlet = 841C -~
__meositiQn at eactor__utl_t~
% by mol ~oLs/hour
-- CH4 3.3 0.34 ;~-
-- C02 11.9 1.Z2 `~ -
-- H2O 15.1 1.55
- - 2 - - - - - -
-- Hz 37.6 3.87
-- C0 32.2 3.31
Molar ratio of H2:C0 at reactor outlet: 1.169:1. `~
__am e Le_9
The same experimental apparatus as disclosed in
Examples 5-8 was used in order to study the reactions
of catalytic partial oxidation of mixtures of `',,',`',~
CH4 :2 :C02 = 100:60:30 (by vol/vol). In this case, the
content of C02 was kept at lower values than as in the
preceding examples. Also in this case, the oxygen
stream was subdivided into partial streams which were ~ `
~ . .:
fed both to the inlet to R1, and to an intermediate ~
20 point between R1 and R2, as well as to an intermediate ~ 2
point between R2 and R3. Furthermore tby pre-heating ` ~ `
the gas reactant streams), inlet temperatures to the
catalytic beds were tested which were higher than in ~ -
the preceding examples. The catalyst used in reactor
25 R1 (Ist adiabatic layer) contained Rh (O.lX by weight)
and Pt (0.5X by weight) deposited on a mixed aluminum
and magnesium oxide. The preparation procedures used
have already been disclosed in the preceding examples. ~ `"Y;i `~
The catalysts contained in the second reactor0 tR2) an~ in the third reactor tR3) ti.e., the second
34 2112519 ~
and third ad;abatic layers) ~ere the sa~e as used in
Examples 5-8 and contained Rh and, respectively, Ir,
deposited on an aluminum and magnesium oxide, and Rh
and Ru deposited on the same support. ~-
S In follo~ing Table 9, the ma;n features of the
experiment are reported
_BLE 9
st_adi_ba_ic_layer
Catalyst
-- composition: Rh (0,1X) + Pt (0,5%) on MgAlOx
-- amount: 4 cc `~
Inlet composition~
-- CH4:02:CO2 = 100 30 30 (volume ratios)
Feed flowrate:
15 -- CH~ = 79.00 Nl~hour -~
-- COz = 23 70 Nl/hour ;~
- - 2 = 23.70 Nl/hour
-- total = 126.40 Nl/hour ; -
Temperatures `~
20 -- inlet = 4000C
-- outlet = 7610C
I I n d _ _ d i _ b 3 _ i c _ l _ y _ _
Catalyst -
-- composition: Rh (0.1%) + Ir (0.5%) on MgAlOx
25 -- amount: 4 cc ~ 9-~
Inlet composition~
-- gas product from the Ist layer 02 added
-- feed flowrate:
- - 2 = 15.8 Nlthour
-- total = 15.8 Nl/hour
~ '. ' `,`.,`~-'
` :- 35. 2112519
Temperatures~
-- inlet = 6000C ,;;~
-- outLet ~ 8530C '~
IIIrd 3diabatic layer ',~
S Catalyst:
-- composition: Rh (0.1%) + Ru (0.5%) on MgAlO~ ~;,;,~'''
-- amount: 5 cc '~
Inlet composition:
-- gas product 'from the'`I'Ind lay'er + 02 added ~,'~
-- feed flowrate:
-- 02 = 7.9 Nl/hour ~'~'s`'
-- total = 7.9 Nl/hour
..`' .' :~'..'. '. ':
Temperatures: '~
~ -- inlet = 6000C ,'6,~
¦ 15 -- outlet = 841C
__m eo i tion_at_reactor__ytle_~
% by mol Mols/hour
-- CH4 3.1 0.34
-- C02 6.9 0.76 ~'~','''~
20 -- H20 12.3 1.34 '~
~- 02 --- ---
-- H2 45,9 5 03 :~--
-- C0 31.8 3.48
Molar ratio of H2:C0 at reactor outlet: 1.445:1.
' 25 i , .
;'~
. , . ,, ;~,.
: .:., ~
