US2013303813A1PendingUtilityA1
Catalyst comprising palladium and silver, and its application for selective hydrogenation
Est. expiryMar 31, 2032(~5.7 yrs left)· nominal 20-yr term from priority
B01J 35/393C10G 45/40B01J 37/024B01J 37/009B01J 37/16B01J 37/10Y02P20/52B01J 23/66B01J 37/0242B01J 37/08C07C 7/163B01J 23/50B01J 23/58C07C 7/167B01J 37/0236B01J 35/19B01J 35/396B01J 35/397B01J 35/613B01J 35/615
50
PatentIndex Score
0
Cited by
0
References
0
Claims
Abstract
Disclosed are a catalyst, its preparation and use in selective hydrogenation, which catalyst has a porous support grain on which are deposited palladium and silver, and at least one alkali and/or alkaline earth metal; the porous support contains a refractory silica, alumina and/or silica-alumina oxide, where at least 80 wt. % of the palladium is distributed in a crust at the periphery of the support, and at least 80 wt. % of the silver is distributed in a crust at the periphery of the support, the local content of palladium at each point along the diameter of the grain follows the same course as the local content of silver.
Claims
exact text as granted — not AI-modified1 . A catalyst comprising a porous support grain on which are deposited palladium and silver, and at least one metal selected from the group consisting of the alkalis and the alkaline earths, the porous support comprising at least one refractory oxide selected from the group consisting of silica, alumina and silica-alumina, the specific surface area of the porous support being within the range 10 to 150 m 2 /g, the palladium content of the catalyst within the range 0.05 to 0.6 wt. %, the silver content of the catalyst within the range 0.02 to 3 wt. %, at least 80 wt. % of the palladium being distributed in a crust at the periphery of the support, the thickness of the said crust being within the range 10 to 160 μm, at least 80 wt. % of the silver being distributed in a crust at the periphery of the support, the thickness of the said crust being within the range 10 to 160 μm, the local content of palladium at each point along the diameter of the grain following the same course as the local content of silver, the sum of the contents of alkali and/or alkaline earth metals being within the range 0.02 to 5 wt. %.
2 . A catalyst according to claim 1 , wherein the course of the content of palladium and the content of silver may be expressed by a proximity ratio PR within the range 0.5 to 2, the said proximity ratio being defined by the following formula:
Proximity
ratio
=
PR
(
y
)
=
Q
(
y
)
Pd
/
Q
(
r
)
Pd
Q
(
y
)
Ag
/
Q
(
r
)
Ag
where:
Q (y) Pd=Sum of the palladium concentrations between the edge of the catalytic grain and a distance y from the edge of the grain (wt. %)
Q (y) Ag=Sum of the silver concentrations between the edge of the catalytic grain and a distance y from the edge of the grain (wt. %)
Q (r) Pd=Total palladium content of the catalytic grain (wt. %)
Q (r) Ag=Total silver content of the catalytic grain (wt. %).
3 . A catalyst according to claim 1 , wherein the said alkali and/or alkaline-earth metal is homogeneously distributed through the support grain with a coefficient R within the range 0.8 to 1.2, the said coefficient R being defined by the following formula.
R
=
∫
-
r
r
c
(
x
)
x
2
x
/
r
2
3
∫
-
r
r
c
(
x
)
x
where the distribution profile c(x) for xε[−r;+r] is obtained with a Castaing microprobe, c being the local concentration locale of the alkali and/or alkaline-earth element, r the radius of the bead, and x the position of the analysis point along the diameter of the grain relative to the centre of this grain.
4 . A catalyst according to claim 1 , wherein the porous support is alumina.
5 . A catalyst according to claim 1 , wherein the porous support grain is in the form of beads or extrudates.
6 . A catalyst according to claim 1 , wherein the said alkali metal is sodium.
7 . A catalyst according to claim 1 , wherein the specific surface area of the said porous support is within the range 65 to 150 m 2 /g and wherein the content of palladium in the catalyst is within the range 0.05 to 0.4 wt. %, the silver content of the catalyst is within the range 0.05 to 0.3 wt. %, at least 80 wt. % of the palladium is distributed within a crust at the periphery of the support, the thickness of the said crust is within the range 10 to 110 μm, at least 80 wt. % of the silver is distributed within a crust at the periphery of the support, and the thickness of the said crust is within the range 10 to 110 μm.
8 . A process for preparing the catalyst according to claim 1 , comprising the following steps:
a step wherein the palladium is introduced onto the support, referred to as step 1, comprising the following steps:
a step 1a) wherein, in an apparatus, a colloidal suspension of palladium oxide or palladium hydroxide is prepared in an aqueous phase by mixing an aqueous solution 1 comprising at least one hydroxide selected from the group consisting of alkali hydroxides and alkaline-earth hydroxides and an aqueous solution 2 comprising at least one palladium precursor, the solution 2 then the solution 1 being poured into the apparatus or solutions 1 and 2 being poured simultaneously into the apparatus,
a step 1b) wherein the said colloidal suspension is impregnated onto the said porous support grain having a specific surface area within the range 10 to 150 m 2 /g,
a step 1c) wherein the said impregnated support obtained in step 1b) is matured,
a step 1d) wherein the catalyst obtained in step 1c) is dried,
a step 1e) wherein the catalyst obtained in step 1d) is calcined,
then a step wherein the silver is introduced, referred to as step 2, comprising the following steps:
a step 2a), wherein the catalyst prepared in accordance with step 1 is reduced by placing it in contact with an aqueous solution comprising at least one liquid phase reducing agent,
a step 2b), wherein the catalyst obtained in step 2a) is filtered,
a step 2c), wherein the catalyst prepared in step 2b) is impregated by placing it in contact, under agitation, with an aqueous solution comprising a silver precursor salt,
a step 2d), wherein the catalyst obtained in step 2c) is filtered,
a step 2e), wherein the catalyst obtained in step 2d) is dried,
a step 2f), wherein the catalyst obtained in step 2e) is calcined, preferably at 450° C. to 700° C.
9 . A process for preparing the catalyst according to claim 8 , wherein, in step 1a), the palladium precursor is selected from the group consisting of palladium chloride, palladium nitrate, and palladium sulphate.
10 . A process for preparing the catalyst according to claim 8 , wherein, in step 2c), the silver precursor is selected from the group consisting of silver nitrate, silver acetate, silver citrate, silver chloride, and silver oxalate.
11 . A process for preparing the catalyst according to claim 8 , wherein, in step 2a), the reducing agent is selected from formic acid, citric acid, ascorbic acid, oxalic acid, sodium formiate, sodium acetate, sodium borohydride, formaldehyde, dextrose, hydrazine and hydrogen.
12 . A catalyst capable of being obtained by the preparation process according to claim 8 .
13 . A process for selective hydrogenation comprising bringing a feed into contact with the catalyst according to claim 1 , the said feed being selected from the group consisting of C3, C4 or C5 steam-cracking and/or catalytic-cracking cuts and steam cracking gasolines.
14 . A process according to claim 13 , wherein the temperature is within the range 0° C. to 500° C., the pressure is within the range 0.1 to 20 MPa, and the hourly space velocity is within the range 0.1 to 50 h −1 for a liquid feed and within the range 500 to 30000 h −1 for a gaseous feed.
15 . A process according to claim 13 , wherein the feed is a C3 steam-cracking and/or catalytic cracking cut.Join the waitlist — get patent alerts
Track US2013303813A1 — get alerts on status changes and closely related new filings.
We store only your email — no account needed. See our privacy policy.