FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
(See Section 10, rule 13)
“A CATALYST COMPOSITION, A PROCESS OF PREPARATION AND
DEHYDROGENATION OF ALKANE”
Name and Address of the Applicant:
RELIANCE INDUSTRIES LIMITED
3
rd Floor, Maker Chamber-IV, 222, Nariman Point,
Mumbai - 400 021, Maharashtra, India
Nationality: IN
The following specification particularly describes the invention and the manner in which it is
to be performed.

2
TECHNICAL FIELD
The present disclosure relates to the field of inorganic chemistry, particularly to
dehydrogenation. The present disclosure describes a catalyst composition for effective
dehydrogenation of alkane to corresponding olefin. The present disclosure further describes a
process of preparing the catalyst composition and to a method of dehydrogenation of alkane
employing the said catalyst composition.
BACKGROUND OF THE DISCLOSURE
Olefins, such as propylene is an important raw material for the production of organic chemicals
such as polypropylene, acrylonitrile, propylene oxide, oxo-alcohols, and also a large variety of
industrial products. At present most of the propylene is produced either through the steam
cracking of naphtha or through the fluid catalytic cracking of gas oils in the refinery. With
shifting of feed from naphtha to ethane in the stem crackers, the production of propylene via
steam cracking was decreased exponentially.
To meet the propylene demand, propylene production technologies like propane
dehydrogenation with capability to produce high purity are attempted. However, propane
dehydrogenation is highly endothermic reaction, limited by the thermodynamic equilibrium
and catalyst deactivation, which are the common phenomenon observed. Selective conversion
of the paraffins, i.e., propane to its corresponding olefins, i.e., propylene requires a suitable
catalyst that has the ability to minimize side reactions such as cracking. Most of the catalysts
reported for commercial dehydrogenation are based on noble metals. The noble metals are
expensive, and regeneration of such catalysts need special care for proper dispersion. On the
other hand, reported non-noble metal catalysts are noted to have relatively reduced activity due
to the properties of support matrix, such as pore volume, surface area, hydrothermally stable
and attrition resistant.
Thus, there is a need for improved dehydrogenation catalyst for effective conversion of
paraffins to corresponding olefins without any of the above mentioned limitations. The present
disclosure describes an improved dehydrogenation catalyst having higher alkane conversion
rate and improved olefin selectivity.
3
STATEMENT OF THE DISCLOSURE
Accordingly, the present disclosure relates to a catalyst composition having improved catalytic
activity for conversion of alkane to corresponding olefins. The catalyst composition is
hydrothermally stable, attrition resistant, low in acidic property and has high oxygen
scavenging capacity.
In some embodiments, the present disclosure relates to a catalyst composition comprising- i.
modified support matrix comprising metal oxide selected from a group comprising potassium
oxide, sodium oxide, lithium oxide, cesium oxide and combinations thereof; ii. promoter
selected from a group comprising cerium oxide, zirconium oxide and a combination thereof;
and iii. chromium oxide.
In some embodiments, the present disclosure relates to a process of preparing the catalyst
composition, the process comprising- impregnating the support matrix in a solution of the metal
oxide selected from a group comprising potassium oxide, sodium oxide, lithium oxide, cesium
oxide and combinations thereof, followed by drying to obtain modified support matrix;
impregnating the modified support matrix in the promoter, followed by drying; and
impregnating the promoter impregnating support matrix in a solution of chromium oxide,
followed by drying; and calcining the chromium oxide impregnated support matrix to obtain
the catalyst composition.
In some embodiments, the present disclosure relates to a method of dehydrogenation of alkane,
said method comprising- contacting the alkane with the catalyst composition; and allowing the
reaction to occur at a temperature ranging from about 550 °C to 650 °C at weight hourly space
velocity (WHSV) ranging from about 0.01 h-1 to 100 h-1 to obtain corresponding olefin in a
dual fluidised reactor system wherein dehydrogenation of alkane takes place in a primary
fluidized bed vessel (reactor) and regeneration of catalyst takes place in secondary fluidized
bed vessel (combustor) by the combustion of coke on catalyst with air
In some embodiments, the present disclosure relates to use of the catalyst composition for
dehydrogenation of alkane for producing corresponding olefin.
4
BRIEF DESCRIPTION OF THE ACCOMPANYING FIGURES
In order that the present disclosure may be readily understood and put into practical effect,
reference will now be made to exemplary embodiments as illustrated with reference to the
accompanying figures. The figures together with detailed description below, are incorporated
in and form part of the specification, and serve to further illustrate the embodiments and explain
various principles and advantages, where:
FIGURE 1 illustrates a block flow diagram of dual-zone dehydrogenation process.
FIGURE 2 illustrates a plot describing effect of oxygen on the equilibrium conversion of
propane to corresponding propylene.
DETAILED DESCRIPTION OF THE DISCLOSURE
Unless otherwise defined, all terms used in the disclosure, including technical and scientific
terms, have meaning as commonly understood by one of ordinary skill in the art to which this
invention belongs. By means of further guidance, term definitions are included for better
understanding of the present disclosure.
As used herein, the singular forms ‘a’, ‘an’ and ‘the’ include both singular and plural referents
unless the context clearly dictates otherwise.
The term ‘comprising’, ‘comprises’ or ‘comprised of’ as used herein are synonymous with
‘including’, ‘includes’, ‘containing’ or ‘contains’ and are inclusive or open-ended and do not
exclude additional, non-recited members, elements or method steps.
The recitation of numerical ranges by endpoints includes all numbers and fractions subsumed
within the respective ranges, as well as the recited endpoints.
The term ‘about’ as used herein when referring to a measurable value such as a parameter, an
amount, a temporal duration, and the like, is meant to encompass variations of ±10% or less,
preferably ±5% or less, more preferably ±1% or less and still more preferably ±0.1% or less of
and from the specified value, insofar such variations are appropriate to perform the present
disclosure. It is to be understood that the value to which the modifier ‘about’ refers is itself also
specifically, and preferably disclosed.
5
Reference throughout this specification to ‘some embodiments’, ‘one embodiment’ or ‘an
embodiment’ means that a particular feature, structure or characteristic described in connection
with the embodiment may be included in at least one embodiment of the present disclosure.
thus, the appearances of the phrases ‘in some embodiments’, ‘in one embodiment’ or ‘in an
embodiment’ in various places throughout this specification may not necessarily all refer to the
same embodiment. It is appreciated that certain features of the disclosure, which are for clarity,
described in the context of separate embodiments, may also be provided in combination in a
single embodiment. Conversely, various features of the disclosure, which are, for brevity
described in the context of a single embodiment, may also be provided separately or in any
suitable sub-combination.
The present disclosure relates to an improved catalyst composition for dehydrogenation of
alkane to corresponding olefin. The catalyst composition has improved catalytic activity,
hydrothermally stable, attrition resistant, low in acidic property and oxygen scavenging
capacity.
In some embodiments of the present disclosure, the catalyst composition comprises-
- modified support matrix comprising metal oxide selected from a group comprising
potassium oxide, sodium oxide, lithium oxide, cesium oxide and combinations thereof;
- promoter selected from a group comprising cerium oxide, zirconium oxide and a
combination thereof; and
- chromium oxide.
In some embodiments of the present disclosure, in the catalyst composition, the support matrix
is selected from a group comprising alumina and silica-alumina.
In some embodiments of the present disclosure, in the catalyst composition, the support matrix
is silica-alumina, wherein the silica is in an amount ranging from about 5 wt.% to 60 wt.%,
including all the values in the range, for instance, 6 wt.%, 7 wt.%, 8 wt.%, 9 wt.% and so on
and so forth, up until 60 wt.%, and alumina is in an amount ranging from about 40 wt.% to 95
wt.%, including all the values in the range, for instance, 41 wt.%, 42 wt.%, 43 wt.%, 44 wt.%
and so on and so forth, up until 95 wt.%.
6
In some embodiments of the present disclosure, the support matrix has total surface area (TSA)
ranging 120 m2
/g to 250 m2
/g, including all the values in the range, for instance, 121 m2
/g, 122
m2
/g, 123 m2
/g, 124 m2
/g, and so on and so forth, up until 250 m2
/g.
In some embodiments of the present disclosure, the support matrix has total pore volume (TPV)
ranging from about 0.5 cm3
/g to 1.2 cm3
/g. In an embodiment, the support matrix has total pore
volume of about 0.5 cm3
/g, about 0.6 cm3
/g, about 0.7 cm3
/g, about 0.8 cm3
/g, about 0.9 cm3/g,
about 1.0 cm3/g, about 1.1 cm3/g or about 1.2 cm3/g.
In some embodiments of the present disclosure, the support matrix has pore diameter ranging
from about 80 °A to 160 °A, including all the values in the range, for instance, 81 °A, 82 °A,
83 °A, 84 °A and so on and so forth, up until 160 °A.
Accordingly, the support matrix of the catalyst composition has total surface area ranging from
about 120 m2
/g to 250 m2
/g, has total pore volume ranging from about 0.5 cm3
/g to 1.2 cm3
/g,
and has pore diameter ranging from about 80 °A to 120 °A.
In one embodiment of the present disclosure, the catalyst composition comprises silica-alumina
having total surface area ranging from about 120 m2
/g to 250 m2
/g, total pore volume ranging
from about 0.5 cm3
/g to 1.2 cm3
/g, and pore diameter ranging from about 80 °A to 120 °A. In
an embodiment, silica to alumina ratio is ranging from about 0.05 to 1.5 (i.e. SiO2/Al2O3: 0.05
to 1.5 wt%/wt%).
In some embodiments of the present disclosure, the metal oxide selected from a group
comprising potassium oxide, sodium oxide, lithium oxide, cesium oxide and combinations
thereof is in an amount ranging from about 0.5 wt.% to 5 wt.%, including all the values in the
range, for instance, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.% and so on and so forth, up until 5
wt.%.
Accordingly, the support matrix of the catalyst composition comprises potassium oxide,
sodium oxide, lithium oxide or cesium oxide in an amount ranging from about 0.5 wt.% to 5
wt.%, including all the values in the range, for instance, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.%
and so on and so forth, up until 5 wt.%. In an embodiment, the support matrix of the catalyst
composition can include combinations of potassium oxide, sodium oxide, lithium oxide or
7
cesium oxide in an amount ranging from about 0.5 wt.% to 5 wt.%, including all the values in
the range, for instance, 0.6 wt.%, 0.7 wt.%, 0.8 wt.%, 0.9 wt.% and so on and so forth, up until
5 wt.%.
In some embodiments of the present disclosure, in the catalyst composition, the promoter is in
an amount ranging from about 1 wt.% to 10 wt.%, including all the values in the range, for
instance, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.% and so on and so forth, up until 10 wt.%.
In some embodiments of the present disclosure, the promoter is a combination of cerium oxide
and zirconium oxide in an amount ranging from about 1 wt.% to 10 wt.%, including all the
values in the range, for instance, 1 wt.%, 2 wt.%, 3 wt.%, 4 wt.% and so on and so forth, up
until 10 wt.%., wherein ratio of cerium and zirconium is ranging from about 0.2 to 0.8. In an
embodiment, ratio of cerium and zirconium in the catalyst composition is about 0.2, about 0.3,
about 0.4, about 0.5, about 0.6, about 0.7 or about 0.8.
In some embodiments of the present disclosure, in the catalyst composition, the chromium
oxide is in an amount ranging from about 10 wt.% to 50 wt.%, including all the values in the
range, for instance, 11 wt.%, 12 wt.%, 13 wt.%, 14 wt.% and so on and so forth, up until 50
wt.%.
Accordingly, the catalyst composition of the present disclosure comprises-
- modified support matrix comprising about 0.5 wt.% to 5 wt.% of metal oxide selected
from a group potassium oxide, sodium oxide, lithium oxide, cesium oxide and
combinations thereof;
- about 1 wt.% to 10 wt.% of promoter comprising cerium oxide, zirconium oxide or
combination of cerium oxide and zirconium oxide; and
- about 10 wt.% to 50 wt.% of chromium oxide.
The inventors of the present disclosure have identified that about 1 wt.% to 10 wt.% of the
promoter comprising cerium oxide, zirconium oxide or combination of cerium oxide and
zirconium oxide captures oxygen in the lattice and release the stored oxygen during reducing
atmosphere. The inventors have also identified that about 0.5 wt.% to 5 wt.% of metal oxide
modifies the support matrix, thereby reducing acidity of the support matrix and suppresses coke
formation. The inventors have also identified that about 10 wt.% to 50 wt.% of the chromium
8
oxide improves selective dehydrogenation of alkanes and suppress side reactions, such as
cracking.
Accordingly, the catalyst composition of the present disclosure comprising combination of
modified support matrix comprising about 0.5 wt.% to 5 wt.% of metal oxide selected from a
group potassium oxide, sodium oxide, lithium oxide, cesium oxide and combinations thereof;
about 1 wt.% to 10 wt.% of promoter comprising cerium oxide, zirconium oxide or
combination of cerium oxide and zirconium oxide; and about 10 wt.% to 50 wt.% of chromium
oxide, i. captures oxygen in the lattice and releases the stored oxygen during reducing
atmosphere; ii. suppress coke formation; iii. improves selective dehydrogenation of alkanes;
and iv. suppresses side reaction, such as cracking.
The catalyst composition of the present disclosure is highly active and hydrothermally stable.
The catalyst composition provides enhanced conversion of alkanes to corresponding olefins by
shifting the thermodynamic equilibrium.
In some embodiments of the present disclosure, the catalyst composition has olefin selectivity
ranging from about 80% to 95%. In an embodiment, the catalyst composition has olefin
selectivity of about 80%, about 81%, about 82%, about 83%, about 84%, about 85%, about
86%, about 87%, about 88%, about 89%, about 90%, about 91%, about 92%, about 93%, about
94% or about 95%.
In some embodiments of the present disclosure, the catalyst composition has alkane conversion
ranging from about 40 wt.% to 55 wt.%. In an embodiment, the catalyst composition has alkane
conversion of about 40 wt.%, about 41 wt.%, about 42 wt.%, about 43 wt.%, about 44 wt.%,
about 45 wt.%, about 46 wt.%, about 47 wt.%, about 48 wt.%, about 49 wt.%, about 50 wt.%,
about 51 wt.%, about 52 wt.%, about 53 wt.%, about 54 wt.% or about 55 wt.%.
Accordingly, the catalyst composition of the present disclosure has olefin selectivity ranging
from about 80% to 95% and alkane conversion ranging from about 40 wt.% to 55 wt.%.
The present disclosure further relates to a process of preparing the catalyst composition
described above.
9
While the subsequent embodiments focus on process of preparing the catalyst composition, the
features and characteristics of the catalyst composition are as described by any of the
embodiments above. For the sake of brevity, and avoiding repetition, each of those
embodiments are not being reiterated here again. However, each of the said embodiments
completely fall within the purview of the process of preparing the catalyst composition.
In some embodiments of the present disclosure, the process of preparing the catalyst
composition comprises-
- impregnating the support matrix in a solution of the metal oxide selected from a group
comprising potassium oxide, sodium oxide, lithium oxide, cesium oxide and
combinations thereof, followed by drying to obtain modified support matrix;
- impregnating the modified support matrix in the promoter, followed by drying; and
- impregnating the promoter loaded support matrix in a solution of chromium oxide,
followed by drying; and
- calcining the chromium oxide impregnated support matrix to obtain the catalyst
composition.
In some embodiments of the present disclosure, prior to impregnating the support matrix in a
solution of metal oxide, the support matrix is subjected to calcination at a temperature ranging
from about 800 °C to 1000 °C, including all the values in the range, for instance, 801 °C, 802
°C, 803 °C, 804 °C and so on and so forth, up until 1000 °C. In an embodiment, calcination is
carried out for a duration ranging from about 1 hour to 8 hours, including all the values in the
range, for instance, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours and so on and so forth, up until 8
hours.
Accordingly, the process of preparing the catalyst composition comprises- subjecting the
support matrix to calcination at a temperature ranging from about 800 °C to 1000 °C, for a
duration ranging from about 1 hour to 8 hours for minimizing the acidity of the support to
below 200 micro mol/gm. Further impregnating the calcined support matrix with the metal
oxide selected from a group comprising potassium oxide, sodium oxide, lithium oxide, cesium
oxide and combinations thereof.
In some embodiments of the present disclosure, in the process of preparing the catalyst
composition, the metal oxide impregnated support matrix is subjected to drying at a
10
temperature ranging from about 90 °C to 150 °C, including all the values in the range, for
instance 91 °C, 92 °C, 93 °C, 94 °C and so on and so forth, up until 150 °C. In an embodiment,
the drying is carried out for a duration ranging from about 1 hour to 10 hours, including all the
values in range, for instance, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours and so on and so forth,
up until 8 hours.
In some embodiments of the present disclosure, in the process of preparing the catalyst, after
impregnating the modified support matrix with the promoter, the drying is carried out at a
temperature ranging from about 90 °C to 150 °C, including all the values in the range, for
instance 91 °C, 92 °C, 93 °C, 94 °C and so on and so forth, up until 150 °C. In an embodiment,
the drying is carried out for a duration ranging from about 1 hour to 10 hours, including all the
values in range, for instance, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours and so on and so forth,
up until 10 hours.
In some embodiments of the present disclosure, in the process of preparing the catalyst
composition, after impregnating the matrix with the chromium oxide, the drying is carried out
at a temperature ranging from about 90 °C to 150 °C, including all the values in the range, for
instance 91 °C, 92 °C, 93 °C, 94 °C and so on and so forth, up until 150 °C. In an embodiment,
the drying is carried out for a duration ranging from about 1 hour to 10 hours, including all the
values in range, for instance, 1.1 hours, 1.2 hours, 1.3 hours, 1.4 hours and so on and so forth,
up until 10 hours.
In some embodiments of the present disclosure, in the process of preparing the catalyst
composition, the promoter impregnated matrix is impregnated with the solution of chromium
oxide for about 2 times to 4 times to achieve desired loading of the chromium. In an
embodiment, the promoter impregnated matrix is subjected to multi-stage impregnation with
the solution of chromium oxide.
In some embodiments of the present disclosure, in the process of preparing the catalyst, the
chromium oxide impregnated support matrix is subjected to calcination at a temperature
ranging from about 600 °C to 700 °C, including all the values in the range, for instance, 601
°C, 602°C, 603 °C, 604 °C and so on and so forth, up until 700 °C. In an embodiment, the
calcination is carried out for a duration ranging from about 2 hours to 5 hours, including all the
values in the range, for instance, 2.1 hours, 2.2 hours, 2.3 hours, 2.4 hours and so on and so
11
forth, up until 5 hours. In an embodiment, during calcination, the heating is carried out at
thermal ramp rate ranging from about 2 °C/min to 5 °C/min. In another embodiment, during
calcination, the heating is carried out at thermal ramp rate of about 2 °C/min, about 3 °C/min,
4 °C/min or about 5 °C/min.
Accordingly, the process of preparing the catalyst composition comprises-
- impregnating calcined support matrix in a solution comprising about 0.5 wt.% to 5 wt.%
of the metal oxide selected from a group comprising potassium oxide, sodium oxide,
cesium oxide and combinations thereof, followed by drying at a temperature ranging
from about 90 °C to 150 °C, for a duration ranging from about 1 hour to 10 hours to
obtain modified support matrix.
- impregnating the modified support matrix in about 1 wt.% to 10 wt.% of the promoter,
followed by drying at a temperature ranging from about 90 °C to 150 °C, for a duration
ranging from about 1 hour to 10 hours;
- impregnating the promoter impregnated support matrix in a solution comprising about
10 wt.% to 50 wt.% of the chromium oxide, followed by drying at a temperature ranging
from about 90 °C to 150 °C, for a duration ranging from about 1 hour to 10 hours; and
- calcining the chromium oxide impregnated support matrix a temperature ranging from
about 600 °C to 700 °C at thermal ramp rate ranging from about 2 °C/min to 5 °C/min,
for a duration ranging from about 2 hours to 5 hours to obtain the composition.
The process of preparing the catalyst composition of the present disclosure provides for an
improved catalyst composition, which is highly active, hydrothermally stable and is capable of
effectively converting alkanes to corresponding olefins by shifting thermodynamic
equilibrium.
The present disclosure further relates to a method for dehydrogenation of alkane employing
the catalyst composition described above.
While the subsequent embodiments focus on the method for dehydrogenation of alkane, the
features and characteristics of the catalyst composition and the manner in which it is prepared
is as described by any of the embodiments above. For the sake of brevity and avoiding
repetition, each of those embodiments are not being reiterated here again. However, each of
12
said embodiments completely fall within the purview of the embodiments relating to the
method for dehydrogenation of alkane.
In some embodiments of the present disclosure, the method of dehydrogenation of alkane
comprises-
- contacting the alkane with the catalyst composition; and
- allowing the reaction to occur at a temperature ranging from about 550 °C to 650 °C at
weight hourly space velocity (WHSV) ranging from about 0.01 h-1 to 100 h-1 to obtain
the corresponding olefin.
In some embodiments of the present disclosure, in the method of dehydrogenation, the reaction
is allowed to occur at a temperature ranging from about 550 °C to 650 °C, including all the
values in the range, for instance, 551 °C, 552 °C, 553 °C, 554 °C and so on and so forth, up
until 650 °C. In an embodiment, the reaction is allowed at weight hourly space velocity
(WHSV) ranging from about 0.01 h-1 to 100 h-1, including all the values in the range, for
instance, 0.02 h-1, 0.03 h-1, 0.04 h-1, 0.05 h-1 and so on and so forth, up until 100 h-1
.
In some embodiments of the present disclosure, in method of dehydrogenation, the reaction is
carried out at a pressure ranging from about 0.1 bar to 10 bar, including all the values in the
range, for instance, 0.2 bar, 0.3 bar, 0.4 bar, 0.5 bar and so on and so forth, up until 10 bar.
In some embodiments of the present disclosure, in the method of dehydrogenation in a reactor
and during the reaction, the vapour residence time is ranging from about 1 seconds to 30
seconds, including all the values in the range, for instance, 2 seconds, 3 seconds, 4 seconds, 5
seconds and so on and so forth, up until 30 seconds. In an embodiment, during the reaction, the
solid residence time is ranging from about 30 seconds to 300 seconds, including all the values
in the range, for instance, 31 seconds, 32 seconds, 33 seconds, 34 seconds and so on and so
forth, up until 300 seconds.
In some embodiments of the present disclosure, in the method of dehydrogenation in a reactor
and during the reaction, the superficial velocity is ranging from about 0.05 m/s to 0.2 m/s,
including all the values in the range, for instance, 0.06 m/s, 0.07 m/s, 0.08 m/s, 0.09 m/s and
so on and so forth, up until 0.2 m/s.
13
In some embodiments of the present disclosure, the method of dehydrogenation comprises
regenerating the catalyst composition, comprising- burning of coke present on the catalyst
composition, there by generating heat; and passing the heat and regenerated catalyst for
dehydrogenation of the alkane.
In some embodiments of the present disclosure, the regeneration of the catalyst composition is
carried out in presence of air or oxygen at a temperature ranging from about 650 °C to 800 °C,
including all the values in the range, for instance, 651 °C, 652 °C, 653 °C, 654 °C and so on
and so forth, up until 800 °C. In an embodiment, the regeneration of the catalyst composition
upon each stage of dehydrogenation is carried out for a duration ranging from about 5 minutes
to 30 minutes, including all the values in the range, for instance, 5 minutes, 6 minutes, 7
minutes, 8 minutes and so on and so forth, up until, 30 minutes. In an embodiment, regeneration
of catalyst takes place in secondary fluidized bed vessel (combustor) by combustion of coke
on catalyst with air. The inventors of the present application have identified a process, wherein
dehydrogenation of alkane takes place in a primary fluidized bed vessel (reactor) and
regeneration of catalyst takes place in secondary fluidized bed vessel (combustor) by the
combustion of coke on catalyst with air.
Accordingly, the method for dehydrogenation of the alkane comprises-
- contacting the alkane with the catalyst composition;
- allowing the reaction to occur at a temperature ranging from about 550 ℃ to 650 ℃ at
weight hourly space velocity (WHSV) ranging from about 0.01 h-1 to 100 h-1 to obtain
corresponding olefin; and
- regenerating the catalyst composition in presence of air or oxygen at a temperature
ranging from about 650 °C to 800 °C for a duration ranging from about 5 minutes to 30
minutes to obtain regenerated catalyst.
In some embodiments of the present disclosure, in the method of dehydrogenation, the alkane
is selected from a group comprising paraffin, propane, ethane, butane and combinations
thereof.
In some embodiments of the present disclosure, in the method of dehydrogenation, the alkane
conversion rate is ranging from about 40% to 55%, including all the values in the range, for
instance, 41%, 42%, 43%, 44% and so on and so forth, up until 55%.
14
In some embodiments of the present disclosure, in the method of dehydrogenation, the olefin
selectivity is ranging from about 80% to 95%, including all the values in the range, for instance,
81%, 82%, 83%, 84% and so on and so forth, up until 95%.
In some embodiments of the present disclosure, in the method of dehydrogenation, the olefin
yield is ranging from about 40% to 95%, including all the values in the range, for instance,
41%, 42%, 43%, 44% and so on and so forth, up until 95%.
Accordingly, the method of dehydrogenation has alkane conversion rate ranging from about
40% to 55%, has olefin selectivity ranging from about 80% to 95% and has olefin yield ranging
from about 40% to 95%.
In some embodiments of the present disclosure, the dehydrogenation of the alkane is carried
out in a dual fluidized bed reactor.
The method of dehydrogenation of the alkane according to the present disclosure has enhanced
conversion of alkanes by shifting the thermodynamic equilibrium. The method also ensures
continuous regeneration of the catalyst composition. Heat required for the dehydrogenation of
the alkane is supplied through the combustion of coke formed over the catalyst composition
during the regeneration. In addition to the heat supplied from combustion of the coke,
supplemental heat is also generated in the reactor in-situ by the combustion of hydrogen by the
lattice oxygen available within the catalyst.
The present disclosure further relates to use of the catalyst composition described above for
dehydrogenation of alkane for producing corresponding olefin.
In some embodiments of the present invention, in said use, the olefin selectivity is ranging from
about 80% to 95%, the alkane conversion rate is ranging from about 40% to 55%, and yield of
the olefin is ranging from about 40% to 95%.
The inventors of the present application have particularly identified that the catalyst
composition of the present application has the potentiality of shifting equilibrium conversion
by scavenging H2 quickly from the system with help of metal oxide and promoter employed in
the catalyst composition.
15
It is to be understood that the foregoing description is illustrative not a limitation. While
considerable emphasis has been placed herein on particular features of this disclosure, it will
be appreciated that various modifications can be made, and that many changes can be made in
the preferred embodiments without departing from the principles of the disclosure. Those
skilled in the art will recognize that the embodiments herein can be practiced with modification
within the spirit and scope of the embodiments as described herein. Similarly, additional
embodiments and features of the present disclosure will be apparent to one of ordinary skill in
art based upon description provided herein.
Descriptions of well-known/conventional methods/steps and techniques are omitted so as to
not unnecessarily obscure the embodiments herein. Further, the disclosure herein provides for
examples illustrating the above-described embodiments, and in order to illustrate the
embodiments of the present disclosure, certain aspects have been employed. The examples
used herein for such illustration are intended merely to facilitate an understanding of ways in
which the embodiments may be practiced and to further enable those of skill in the art to
practice the embodiments. Accordingly, following examples should not be construed as
limiting the scope of the embodiments herein.
EXAMPLES
Example 1: Preparation of the catalyst composition
Potassium precursor solution was prepared by dissolving about 1 wt.% to 3 wt.% of potassium
precursor salt in distilled water. About 100 gm of calcined silica alumina support matrix was
dropped into the potassium precursor for loading of the potassium onto the support matrix,
followed by drying at a temperature of about 120 °C for a duration of about 12 hours to obtain
modified support matrix. The modified support matrix was dropped in a solution of ceriazirconia precursor salt for loading of the ceria-zirconia onto the modified support matrix,
followed by drying at a temperature of about 125 °C for a duration of about 4 hours. The ceriazirconia impregnated support matrix was dropped in a solution of chromium precursor salt for
loading of the chromium onto the ceria-zirconia impregnated modified support matrix,
followed by drying at a temperature of about 125 °C for a duration of about 6 hours. The
chromium loaded support matrix was subjected calcination at a temperature of about 650 °C
for a duration of about 4 hours, to obtain the catalyst composition.
16
Example 2: Evaluating stability of the support matrix of the catalyst composition
Hydrothermal stability of the support matrix was performed by carrying out hydrothermal
deactivation at a temperature of about 800 °C for a duration of about 24 hours in steam purging.
The mechanical strength of the support is performed by measuring the attrition index in an
attrition testing unit as per ASTM D5757 method.
Table 1 describes characteristics of varied silica-alumina based support matrix.
S. No.
Support
matrix (SilicaAlumina)
Catalyst
condition
TSA
(m2
/g)
TPV
(cc/g)
Pore
diameter
(°A)
Attrition
index
(%)
1
SAR = 0.11
Fresh 202 0.72 134 4.3
2 Steamed 176 0.61 141 5.8
3
SAR = 0.26
Fresh 209 0.72 139 2.8
4 Steamed 181 0.64 143 3.8
5
SAR = 0.19
Fresh 224 0.78 137 2.4
6 Steamed 191 0.68 141 3.1
7
SAR = 0.27
Fresh 218 0.69 124 2.1
8 Steamed 177 0.58 129 3.3
9
SAR = 0.48
Fresh 239 0.81 134 2.1
10 Steamed 202 0.75 140 2.9
11
SAR = 0.68
Fresh 240 0.79 132 5.6
12 Steamed 210 0.74 135 6.2
*SAR- silica to alumina ratio.
Table 1:
Data in Table 1 demonstrates that surface area and pore volume of the support matrix is reduced
slightly whereas slight increase in attrition index was noted. Further, it can be noted that support
matrix with SAR of about 0.68 possess comparatively higher surface area and pore volume,
even after severe hydrothermal deactivation.
Example 3: Dehydrogenation of alkane
Propane was subjected to dehydrogenation in presence of the catalyst composition of the
present disclosure at a temperature of about 6202°C for a duration of about 15 min, at a pressure
of about 1bar and at weight hourly space velocity of about 3.9 h-1
.
Table 2 describes results of the dehydrogenation of the propane by the catalyst composition of
the present disclosure.
Propane conversion 49.6
17
Propylene selectivity 90.2
Methane selectivity 1.68
Ethane selectivity 3.43
Ethylene selectivity 3.71
C4 selectivity 0.98
Table 2:
Example 4: Comparative Example
Dehydrogenation was carried out by employing the components as described in Table 3. The
dehydrogenation was carried out at a temperature of about 625°C for a duration of about 15, at
a pressure of about 1 bar and at weight hourly space velocity of about 2 h-1
.
Silicaalumina
matrix
(Control)
5 wt.% K2O on
silica-alumina
matrix
(Comparative
Example 1)
24wt.% Cr2O3, 5
wt.% K2O on
silica-alumina
matrix
(Comparative
Example 2)
31 wt.% Cr2O3,
3.2 wt.% CeO2,
5.4 wt.% ZrO2,
3.3 wt.% K2O on
silica-alumina
matrix (Catalyst
composition of
the present
disclosure)
47 wt.% Cr2O3,
2.6 wt.% CeO2,
4.4 wt.% ZrO2,
2.3 wt.% K2O on
silica-alumina
matrix (Catalyst
composition of
the present
disclosure)
Propane
conversion
(%)
9.3 10 26 42.6 51
Propylene
selectivity
(%)
2.5 2.7 65 87.1 90.7
Methane
selectivity
(%)
69.1 68.8 23.3 5 3.2
Ethane
selectivity
(%)
26.2 25.9 6.5 4.8 2.3
Ethylene
selectivity
(%)
1.5 1.8 3.7 0.8 0.8
C4
selectivity
(%)
0.7 0.8 1.5 2.3 3
Table 3:
18
The data in Table 3 demonstrates that the catalyst composition of the present application has
highest olefin selectivity (for e.g., propylene selectivity) of 87.1% and 90.7%, respectively
when compared to Control, Comparative Example 1 and Comparative Example 2.
Example 5: Evaluating stability of the catalyst composition of the present disclosure
Propane dehydrogenation was carried out with the catalyst composition of the present
disclosure. The propane dehydrogenation was carried out at a temperature of about 605 °C to
610 °C, at a WSHV of 1.8 h-1 and 2.1 h-1 for about 40 cycles of reaction and regeneration for
about 48 to 92 hours continuous operation for a catalyst composition of 45 wt.% Cr2O3, 2.3
wt.% CeO2, 4.2 wt.% ZrO2, 2.1 wt.% K2O on silica-alumina matrix. The regeneration was
carried out for 5 to 30 minutes at 700 °C. Data in Table 4 demonstrates that the catalyst
composition remained stable even at 40th cycle, while retaining almost same propane
conversion rate as that of the 1st cycle.
Cycles 1
st 10th 25th 40th

Temperature, ℃ 608 606 6610 605
Propane conversion (%) 44.69 44.96 44.4 44.18
Propylene selectivity (%) 90.1 90.8 89.9 91.5
Methane selectivity (%) 3.7 3.1 3.8 2.9
Ethane selectivity (%) 2.7 2.3 2.9 2.2
Ethylene selectivity (%) 1.3 1 0.8 1.1
C4 selectivity (%) 2.2 2.8 2.6 2.3
Table 4:
Additional embodiments and features of the present disclosure will be apparent to one of
ordinary skill in art based on the description provided herein. The embodiments herein provide
various features and advantageous details thereof in the description. Descriptions of wellknown/conventional methods and techniques are omitted so as to not unnecessarily obscure the
embodiments herein.
The foregoing description of the specific embodiments reveal the general nature of the
embodiments herein that others can, by applying current knowledge, readily modify and/or
adapt for various applications such specific embodiments without departing from the generic
concept, and, therefore, such adaptations and modifications should and are intended to be
19
comprehended within the meaning and range of equivalents of the disclosed embodiments. It
is to be understood that the phraseology or terminology employed herein is for the purpose of
description and not of limitation. Therefore, while the embodiments in this disclosure have
been described in terms of preferred embodiments, those skilled in the art will recognize that
the embodiments herein can be practiced with modification within the spirit and scope of the
embodiments as described herein.
Throughout this specification, the term ‘combinations thereof’ or ‘any combination thereof’ or
‘any combinations thereof’ are used interchangeably and are intended to have the same
meaning, as regularly known in the field of patents disclosures.
As regards the embodiments characterized in this specification, it is intended that each
embodiment be read independently as well as in combination with another embodiment. For
example, in case of an embodiment 1 reciting 3 alternatives A, B and C, an embodiment 2
reciting 3 alternatives D, E and F and an embodiment 3 reciting 3 alternatives G, H and I, it is
to be understood that the specification unambiguously discloses embodiments corresponding
to combinations A, D, G; A, D, H; A, D, I; A, E, G; A, E, H; A, E, I; A, F, G; A, F, H; A, F, I;
B, D, G; B, D, H; B, D, I; B, E, G; B, E, H; B, E, I; B, F, G; B, F, H; B, F, I; C, D, G; C, D, H;
C, D, I; C, E, G; C, E, H; C, E, I; C, F, G; C, F, H; C, F, I, unless specifically mentioned
otherwise.
While considerable emphasis has been placed herein on the particular features of this
disclosure, it will be appreciated that various modifications can be made, and that many
changes can be made in the preferred embodiments without departing from the principles of
the disclosure. These and other modifications in the nature of the disclosure or the preferred
embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it
is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely
as illustrative of the disclosure and not as a limitation.

WE CLAIM:
1. A catalyst composition comprising-
- modified support matrix comprising metal oxide selected from a group comprising
potassium oxide, sodium oxide, lithium oxide, cesium oxide and combinations
thereof;
- promoter selected from a group comprising cerium oxide, zirconium oxide and a
combination thereof; and
- chromium oxide.
2. The catalyst composition as claimed in claim 1, wherein the support matrix is selected
from a group comprising alumina and silica-alumina, wherein in the silica-alumina, the
silica is in an amount ranging from about 5 wt.% to 60 wt.% and the alumina is in an
amount ranging from about 40 wt.% to 95 wt.%.
3. The catalyst composition as claimed in claim 1, wherein the promoter is in an amount
ranging from about 1 wt.% to 10 wt.%.
4. The catalyst composition as claimed in claim 1, wherein the promoter is a combination
of cerium oxide and zirconium oxide, wherein ratio of cerium and zirconium is ranging
from about 0.2 to 0.8.
5. The catalyst composition as claimed in claim 1, wherein the metal oxide selected from
a group comprising potassium oxide, sodium oxide, lithium oxide, cesium oxide and
combinations thereof is in an amount ranging from about 0.5 wt.% to 5 wt.%.
6. The catalyst composition as claimed in claim 1, wherein the chromium oxide is in an
amount ranging from about 10 wt.% to 50 wt.%.
7. The catalyst composition as claimed in claim 1, wherein the support matrix has total
surface area (TSA) ranging from about 120 m2
/g to 250 m2
/g; has total pore volume
(TPV) ranging from about 0.5 cm3
/g to 1.2 cm3
/g; and has pore diameter ranging from
about 80 °A to 160 °A.
8. The catalyst composition as claimed in claim 1, wherein the catalyst composition has
olefin selectivity ranging from about 80% to 95% and paraffin conversion is ranging
from about 40 wt.% to 55 wt.%
9. A process of preparing the catalyst composition as claimed in claim 1, said process
comprisinga) impregnating the support matrix in a solution of the metal oxide selected from
a group comprising potassium oxide, sodium oxide, lithium oxide, cesium oxide
21
and combinations thereof, followed by drying to obtain modified support
matrix;
b) impregnating the modified support matrix in the promoter, followed by drying;
and
c) impregnating the support matrix of step b) in a solution of chromium oxide,
followed by drying; and
d) calcining the chromium oxide impregnated support matrix to obtain the catalyst
composition.
10. The method as claimed in claim 9, wherein the acidity of support matrix is maintained
in the range of 50 to 200 micro mol/gm prior to impregnation metal oxide by calcination
11. The process as claimed in claim 9, wherein the drying in step a) is carried out at a
temperature ranging from about 90 °C to 150 °C, for a duration ranging from about 1
to 10 hr; the drying in step b) is carried out at a temperature ranging from about 90 °C
to 150 °, for a duration ranging from about 1 to 10 hrs; and the drying in step c) is
carried out at a temperature ranging from about 90 °C to 150 °, for a duration ranging
from about 1 to 10 hrs.
12. The process as claimed in claim 9, wherein the calcining is carried out at a temperature
ranging from about 600 °C to 700 °C at thermal ramp rate ranging from about 2 °C/min
to 5 °C/min, for a duration ranging from about 2 hours to 5 hours.
13. A method for dehydrogenation of alkane, said method comprising-
- contacting the alkane with the catalyst composition as claimed in claim 1; and
- allowing the reaction to occur at a temperature ranging from about 550 ℃ to 650
℃ at weight hourly space velocity (WHSV) ranging from about 0.01 h-1 to 100 h-1
to obtain corresponding olefin.
14. The method as claimed in claim 13, wherein the dehydrogenation is carried out at a
pressure ranging from about 0.1 bar to 10 bar.
15. The method as claimed in claim 13, wherein the method comprises regenerating the
catalyst composition in presence of air or oxygen at a temperature ranging from about
650 °C to 800 °C for a duration ranging from about 5 minutes to 30 minutes.
16. The method as claimed in claim 14, wherein the regeneration comprises- burning of
coke present on the catalyst composition, thereby generating heat; and passing the heat
and regenerated catalyst for dehydrogenation of the alkane.
17. The method as claimed in claim 13, wherein the alkane is selected from a group
comprising paraffin, Propane, Ethane, Butane and combinations thereof,
22
18. The method as claimed in claim 13, wherein the method for dehydrogenation has alkane
conversion rate ranging from about 40 % to 55%; has the olefin selectivity ranging from
about 80% to 95%; and wherein yield of the olefin is ranging from about 40% to 95%.
19. The method as claimed in claim 13, wherein the dehydrogenation of the alkane is
carried out in a dual fluidized bed reactor.
20. Use of the catalyst composition as claimed in claim 1, for dehydrogenation of alkane
for producing corresponding olefin.
21. The use as claimed in claim 20, wherein the olefin selectivity is ranging from about 80
% to 95%; the alkane conversation rate is ranging from about 40% to 55%; and
wherein yield of the olefin is ranging from about 40% to 95%.