Catalyst – solid sorbent – or support therefor: product or process – Catalyst or precursor therefor – Metal – metal oxide or metal hydroxide
Reexamination Certificate
2001-11-30
2004-01-13
Dunn, Tom (Department: 1754)
Catalyst, solid sorbent, or support therefor: product or process
Catalyst or precursor therefor
Metal, metal oxide or metal hydroxide
C502S349000
Reexamination Certificate
active
06677271
ABSTRACT:
DESCRIPTION
The invention relates to a catalyst which can be employed for the hydrogenation of functional groups of organic compounds in the presence of water, in particular for the hydrogenation of nitro groups in nitroaromatics to give the corresponding amines in the presence of water or for the hydrogenation of aldoses and ketoses to the corresponding sugar alcohols in the presence of water, and to a process for its preparation.
The industrially most frequent applications of the hydrogenation of functional groups of organic compounds are the hydrogenation of aldoses or ketoses to the corresponding sugar alcohols or of nitroaromatics to the corresponding amines.
The hydrogenations are in general carried out either in a fixed-bed reactor or in a batch reactor. On the industrial scale, hydrogenations are most frequently performed in the liquid phase using a suspended catalyst, the processes differing by the reaction temperature, the pressure, the catalyst, the solvents and the nature of the reaction procedure. Catalysts used here are various catalyst systems, such as, for example, nickel-containing catalysts. The catalytic hydrogenation of glucose to sorbitol using a nickel-SiO
2
—Al
2
O
3
catalyst is disclosed in NL 8 102 190. The use of nickel-copper supported catalysts for the hydrogenation of glucose is disclosed in DD 217 996. Supports used are SiO
2
, Al
2
O
3
and SiO
2
·Al
2
O
3
. In DD 156 175, the obtainment of sorbitol by hydrogenation of glucose in the presence of an Ni—SiO
2
catalyst is described. According to patent specification SU 565 040, hydrogenation to sorbitol on Raney nickel catalysts at a catalyst concentration of 5 to 6%, temperatures of 110 to 150° C. and pressures of 40 to 60 bar proceeds with obtainment of good yields after 1 to 2 hours. U.S. Pat. No. 4,694,113 describes a two-stage process for the hydrogenation of glucose to sorbitol, approximately 95% of the glucose being hydrogenated in the presence of a nickel catalyst to give sorbitol in the first stage and, after removal of the nickel catalyst, the remainder of the glucose being hydrogenated to sorbitol using an Ru catalyst.
JP 551 33 33 discloses the hydrogenation of 2,4-dinitrotoluene and 2,6-dinitrotoluene in the presence of the catalysts Pd/C, Raney nickel, Raney cobalt or platinum black.
EP-A 98 681 discloses a nickel-kieselguhr supported catalyst for the hydrogenation of dinitrobenzophenone to the corresponding diamine.
In DE-A 35 37 247, the hydrogenation of dinitro compounds to the diamines in the presence of modified Raney nickel catalysts is described.
EP-A 0 335 222 discloses the use of nickel-Al
2
O
3
/ZrO
2
supported catalysts for the hydrogenation of nitrites, aromatics, nitro compounds and olefins. The specification discloses, inter alia, the simultaneous precipitation of nickel, zirconium and aluminum on supports at 50 to 120° C. and at a pH of 7.3 to 9.0, the supports employed being active carbon, Al
2
O
3
, SiO
2
, kieselguhr and others.
SU patent 28 31 85 discloses nickel-Al
2
O
3
/ZrO
2
catalysts which were prepared by precipitating nickel and Al
2
O
3
on ZrO
2
.
According to the teaching of U.S. Pat. No. 2,564,331, a nickel-ZrO
2
catalyst is prepared by precipitating a nickel and zirconyl carbonate mixture with subsequent washing, drying and reduction at 250 to 350° C., the catalyst containing at most 10 mass % of ZrO
2
.
The precipitation of insoluble carbonates is also disclosed in DE-B 1 257 753, the precipitation process being induced by evaporation of CO
2
and NH
3
from a mixed salt solution of ammonium zirconyl carbonate and nickel ammine carbonate.
EP-A 0 672 452 discloses catalysts for the hydrogenation of organic compounds, which essentially contain 65 to 80 mass % of nickel, calculated as NiO, 10 to 25 mass % of SiO
2
, 2 to 10 mass % of zirconium, calculated as ZrO
2
and 0 to 10 mass % of aluminum, calculated as Al
2
O
3
, the sum of the content of SiO
2
and Al
2
O
3
being at least 15 mass %. These catalysts are prepared by addition of an acidic aqueous solution of Ni, Zr and, if desired, aluminum compounds to a basic aqueous solution or suspension of silicon compounds and, if desired, aluminum compounds. During the precipitation, the pH is first lowered to 4.0 to 6.5 and subsequently adjusted to 7 to 8. The precipitation product is dried, calcined and shaped.
The previously known nickel hydrogenation catalysts all have the disadvantage that under the hydrothermal reaction conditions both of the hydrogenation of glucose and of nitroaromatics a rapid aging of the catalysts occurs.
The technical problem underlying the present invention is thus to make available nickel-containing supported catalysts which, in particular under the hydrothermal reaction conditions of the hydrogenation of glucose and nitroaromatics, have a higher lifespan than the conventional catalysts.
This problem is achieved according to the invention by making available a catalyst, in particular for the hydrogenation of functional groups of organic compounds, in particular for the hydrogenation of glucose to sorbitol or of nitro groups in nitroaromatics to the corresponding amines in the presence of water, comprising nickel on a support, the catalyst being reduced and stabilized, contains nickel crystallites having a monomodal nickel crystallite size distribution, a nickel content of 25 to 60 mass % (based on the total mass of the catalyst), in particular 25 to 59 mass % (based on the total mass of the catalyst) and a degree of reduction of at least 65%. The degree of reduction is determined after a one-hour afterreduction of the stabilized catalyst at 100° C. in a stream of hydrogen (loading: 1 000 v/vh).
The invention solves this problem also by the making available of a process for the preparation of such a catalyst.
The invention provides in a particularly preferred embodiment that the above-mentioned catalyst has a monomodal nickel crystallite size distribution, the maximum of the nickel crystallite size distribution being 25 to 90 angstroms, in particular 30 to 90 angstroms.
In a further preferred embodiment, it is provided that the above-mentioned catalyst is supported on a zirconium-containing support, preferably contains ZrO
2
, ZrO
2
HfO
2
, SiO
2
·ZrO
2
, SiO
2
·ZrO
2
HfO
2
or mixtures of at least two substances thereof or consists of these.
In a particularly preferred embodiment, the SiO
2
content is 0 to 40 mass % (based on the total mass of the catalyst). In a further preferred embodiment, the ZrO
2
content is 20 to 75 mass % (based on the total mass of the catalyst). In a further preferred embodiment, the HfO
2
content is 0 to 7.5 mass % (based on the total mass of the catalyst).
In a particularly preferred embodiment of the invention, the reduced and stabilized catalysts can be employed as powders having particle sizes of 1 to 100 &mgr;m, preferably of 2 to 30 &mgr;m. Of course, shaped articles can also be employed.
The catalysts according to the invention are distinguished in an advantageous and surprising manner by their prolonged lifespan with identical or improved catalytic activity compared with conventional catalysts. Catalysts of the monomodal nickel crystallite size distribution according to the invention have, in particular under hydrothermal reaction conditions, a considerably prolonged lifespan compared with conventional catalysts.
In connection with the present invention, a monomodal nickel crystallite size distribution is understood as meaning a distribution of the nickel crystallites according to which only a maximum of the crystallite size distribution is present.
In connection with the present invention, the term degree of reduction is understood as meaning the proportion of the metallic nickel in the total nickel content of the stabilized catalyst which is present after a one-hour afterreduction at 100° C.
The invention also relates in a further embodiment to a process for the preparation of the above-mentioned catalyst. The invention thus also relates to a process for the preparation of a nickel-containing supported catalyst, in particular of a cat
Birke Peter
Geyer Reinhard
Kraak Peter
Schodel Rainer
Dunn Tom
Ildebrando Christina
Kataleuna GmbH Catalysts
Ostrolenk Faber Gerb & Soffen, LLP
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