JPS5926333B2 - hydrogen transfer catalyst - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of the Invention] The present invention relates to a hydrogen transfer catalyst, and more particularly, it comprises a platinum group metal catalyst supported on graphite-containing carbon of a novel form, and is particularly suitable for hydrogen transfer catalysts for hydrocarbons. The present invention relates to hydrogen transfer catalysts suitable for use in hydrogen transfer reactions such as hydrogenation, dehydrogenation and/or dehydrocyclization.

[Purpose and main points of the invention]

One object of this invention ltA (1) the basal plane surface area is at least 100 m''/y; (2) the ratio of BET surface area to basal plane surface area is not more than 5:1; and (3) the basal plane surface area to edge surface area. An object of the present invention is to provide a new form of graphite-containing carbon-supported hydrogen transfer catalyst having a ratio of at least 5:1.

Graphite-containing carbons include a crystalline layered structure in which the component atoms form multiple layers that are held together by relatively weak Van der Waals fractional forces. The surface area of the crystals of this material is mostly formed by the basic planes of the layers and less by the edges of the layers. There is usually some amorphous carbon present along with the crystalline material. The basic surface area is 1.00 by measuring the heat of adsorption of n-dotriacontane from n-heptane.
Jy-1 is measured as a basal surface area of 19.3771"V-".

Similarly, the edge surface area measures the heat of adsorption of n-butanol from n-heptane, and 1.00 J7-1 is determined as an edge surface area of 6.7 m2y-1. The heat of adsorption is determined by “゜Chemistry and Industry゛2013, 1
965, p. 482-485. BE
The T surface area is determined by J. Am. C? M. sOc6Ol3O9,
Brunauer.EmmetandTel (1938).
This is the surface area measured by the nitrogen adsorption method of

This corresponds to the total surface area, ie, the basic planar surface area of the crystal, the edge surface area of the crystal, and the ground area of the amorphous carbon portion. This new form of graphite-containing carbon can be used as a catalyst support for platinum group metals, and the supported metal catalysts are effective in hydrogen transfer reactions.

Thus, according to another aspect of the invention, (1) the carrier (a) has a basic planar surface area of at least 100 m''/7
and (b) the ratio of BET surface area to basic plane surface area is 5
: not more than 1, and (c) a graphite-containing carbon having a base planar surface area to edge surface area ratio of at least 5:1, and (2) 0.0 of the total weight of the catalyst as an active component.
A catalyst is provided comprising from 1 to 10% by weight, preferably from 0.1 to 5% by weight, of supported platinum group metal.

Platinum group metals include ruthenium, rhodium, palladium,
Means osmium, iridium, platinum and gold.

Preferred metals are platinum itself and iridium.

The basic plane surface area of graphite-containing carbon is 150
Preferably, the rr is within the range of 1/7 to 1000 m°/7.

If this area is larger than 1000Tr1/7, it does not have sufficient strength as a catalyst carrier. The ratio of BET surface area to basal plane surface area is the theoretical minimum value of 1.
The closer it is, the higher the quality of the material.

That is, the proportion of crystalline substances becomes high and the proportion of amorphous substances becomes low. For practical reasons, this ratio is preferably in the range 2:1 to 1,01:1. Preferably, the ratio of base planar surface area to edge surface area is greater than 10:1, and most preferably greater than 300:1.

Preferably, the graphite-containing carbon support has a pH in the range of 5 to 9, more preferably 6 to 8, most preferably about 7, and 1% by weight.
It is preferable to contain the following adsorbed oxygen, and more preferably to contain 0.5% by weight or less of adsorbed oxygen.

The lower the adsorbed oxygen, the closer the pH will be to 7. The graphite-containing carbon must be of high purity. For example, the ash content must be below 0.1% by weight, preferably below 0.05%, and below 0.0% by weight.
More preferably 2% or less. Preferably, the catalyst composition also contains a small proportion of modifying metal ions selected from alkali metal ions and alkaline earth metal ions.

Modifying metal ions significantly increase the dehydrocyclization activity of platinum group metals. The preferred amount of modifying metal is 10 to 300 atomic percent of the platinum group metal. Although any alkali metal is suitable, indium is preferred. Alkaline earth metals include magnesium, calcium,
Strontium or barium. The particle size of the graphite-containing carbon is not critical and can be controlled in known ways in relation to its intended use.

Fine particle ranges are used in slurry processes, and granular forms are used in fixed bed processes. Graphite is (a
) Activated carbon derived from coconut charcoal, coal, peat, etc.
(b) carbon blacks, (c) carbons made by coking petroleum residues, and (to) lipophilic graphites such as those made by the method described in British Patent No. 1,168,785. carbon in the form of carbon.

The carrier has a BE within the range of 100 to 30007TI/7.
Carbon having a surface area of 90
0°C to 3300°C, preferably 1500'C to 27
It can be produced by heating at a temperature of 0.000C for a sufficient time to produce graphite-containing carbon.

Preferably, the carbon used as the starting material has a BET surface area of at least 500 i/7 at about 1000° C. prior to the heat treatment described above.

The preparation of the graphite-containing carbon is a combination of the selected carbon type and heat treatment under inert and oxidizing conditions selected to optimize the ratio of BET to base planar surface area and base planar surface area to edge surface area. Varies depending on use.

Heating in an inert gas increases the proportion of graphitic material. That is, the first ratio decreases and the second ratio increases. The most common form of carbon is
Although this treatment results in a significant reduction in total surface area, this is not always the case and some forms of carbon exhibit relatively little surface area loss upon heating. Oxidation under carefully controlled conditions increases surface area in comparison.

Preparation of carbon supports typically and commonly (follows)
It includes three steps.

(1) initial heat treatment at a temperature between 900°C and 3300°C in an inert gas; (2) between 300°C and 120°C;
an oxidation step carried out at a temperature between 0° C. and (3) a second heat treatment (1 ) and (3), a suitable atmosphere for use at temperatures up to 1000° C. includes nitrogen.

Above this temperature, it is preferable to use, for example, argon or helium as inert gas. Suitable oxidizing media in step (2) include air, water vapor and carbon dioxide. If air is used, 3
Temperatures in the range of 00°C to 450°C are preferred, and when using water vapor or carbon dioxide, temperatures in the range of 800°C to 12°C are preferred.
Temperatures within the range of 00°C are preferred. During heating in an inert atmosphere, it is believed that at least a portion of the carbon is converted to graphite and adsorbed organic oxygen-containing groups such as ketones, hydroxyls, carboxylic acids and the like are removed.

The absence of organic oxygen-containing groups (less than 1%) in the treated carbon is important in connection with the selectivity of catalysts using this carbon as support. This is because oxygen-containing groups have been reported to promote side reactions. The catalyst is prepared by impregnating a graphite-containing carbon support with a solution of a reducible platinum group metal compound and reducing the reducible compound to the metal.

Suitable solutions include aqueous solutions of platinum tetramine chloride, platinum tetramine hydroxide, and chloroplatinic acid.

Suitable impregnation conditions are a temperature of 20 DEG C. to 90 DEG C., an impregnation time of 1 to 6 hours, and a solution concentration of 10-4 to 1 molar. After each impregnation the catalyst is heated, for example, from 100°C to 250°C.
Dry for 1 to 24 hours.

The amount of modifying metal ions that can be added to the catalyst is
Catalysts made from chloroplatinic acid or similar compounds are
This is much higher than that of catalysts made from tetramine complexes. The highest activity is retained in the former up to about 300 atomic percent and in the latter up to about 150 atomic percent. Before use, the platinum group metal is heated, for example, in a reducing atmosphere, preferably in a flowing hydrogen stream of 500 to 10,000 v/v/hr, at a rate of 200. The reduction is preferably carried out by heating at a temperature of 1 to 700°C, preferably 300 to 600°C, for 1 to 5 hours.

Preferably, the alkali or alkaline earth metal ions are added before reducing the platinum group metal. The catalyst is particularly suitable for acyclic, linear hydrocarbons having at least 6 carbon atoms or for at least 6
It is suitable for dehydrocyclizing hydrocarbons having a linear structure having 5 carbon atoms.

Preferred hydrocarbons are paraffins, but olefins may also be used. A particularly suitable feedstock is C6-. 10
are paraffinic hydrocarbons which, when used, allow benzene and/or lower alkyl aromatics to be obtained in good yields with minimal side reactions. The feedstock may be pure hydrocarbons or a mixture of non-linear hydrocarbons. Such mixtures may also contain naphthenes and aromatics, e.g.
It may also be a petroleum fraction, especially a petroleum fraction boiling in the range from 60 to 250°C. Sulfur compounds in the feedstock are generally undesirable for platinum group metal catalysts. Preferably, the sulfur content in the feedstock is below 10 ppm (by weight), especially 1 ppm (by weight). Thus, according to another aspect of the invention, there is provided a process for hydrogen transfer of hydrocarbons, which comprises contacting the hydrocarbons with the above-mentioned catalyst under conversion conditions.

Broad and preferred ranges of operating conditions for dehydrogenation and/or dehydrocyclization are as follows. The catalyst is also suitable for use in the hydrogenation of aromatic hydrocarbons such as benzene and other compounds such as olefins and acetylenes.

A broad range of operating conditions and a preferred range of operating conditions for hydrogenation are as follows. [Examples of the invention] Next, examples of the invention will be shown. Examples 4, 7 and 8
is not an example of the invention and is for comparison only.

Example 1 Carbon production CabOtCOrpOr
atiOn) from “Black Pearls 71” (Bla
Carbon Black 45y, sold under the tradename ekPearls7l), was heated to 1000° C. under a nitrogen atmosphere to remove volatiles and cooled to room temperature (weight loss 11.4%).

This sample was then heated from room temperature to 27°C in an argon atmosphere.
00°C and held at this temperature for approximately 30 minutes, then cooled (another 2.3% weight loss). This second heating and cooling process took approximately 3 hours. After cooling, the carbon had a mottled black and gray appearance and had the following analytical values: BET surface area 180T1? /y
Base surface area 150 m"/t Edge surface area 0.36771"/T BET/base ratio 1.2: 1 Base/edge ratio 427:1 pH 7 (measured as a slurry with water) %Graphite 30% by weight (X- Linear diffraction) % Amorphous carbon 70% by weight Total metal content 13 ppm Ash content 0% Adsorbed oxygen Zero As a result of the heat treatment, the total weight loss was 13.7% by weight.

The carbon is believed to be spherical with a diameter of 200-400λ and has an external graphite skin.

Preparation of the catalyst Impregnated with an aqueous solution of 1/10 mol Pt(NH3)4(0H)2 at 90 °C for 4 h,
Then, by drying at 120°C for 2 hours, 0.7
% by weight of platinum was added to the support.

A portion of this impregnated material was then impregnated with an aqueous solution containing 0.74 grams of 11-equivalent lysodium carbonate for 2 hours at 90°C and then at 110°C for 2 hours.
After drying for an hour, it was sieved to a size of 40100 BBS mesh and then reduced for 2 hours at 500° C. in a flowing hydrogen stream of 4000 v/v/h.

The resulting catalyst contained 600 ppm sodium. This corresponds to 73 atomic percent of platinum. The catalyst was continuously stirred during the impregnation of platinum and sodium and during the removal of water to ensure uniform distribution of both components in and between the catalyst pellets.

Use of the carbon produced as described above as a catalyst carrier (
1) 0.225y of catalyst in a microreactor for 5
At 00°C and atmospheric pressure, the molar ratio of hydrogen to n-hexane is 7:
It was used in the dehydrocyclization reaction of n-hexane at a liquid hourly space velocity of 1 and a liquid hourly space velocity of 4 v/v/hour.

Mitaroreactor 1 had a catalyst capacity of 0.45 ml. (2) A portion of the above catalyst in which the sodium addition step was omitted was also tested under the same conditions.

The results are as follows. Example 2 Trademark name ゛゜Black from Kabot Corporation
A sample of carbon black sold as Pearls 2''' was heated in two stages as described in Example 1;
and cooled (total weight loss 32% by weight).

After cooling, the carbon had a mottled black and gray appearance and had the following analytical values:

The aforementioned support was treated as described in Example 1 to produce 0.7% by weight platinum and 600 ppm
A catalyst was prepared containing sodium.

(1) n-hexane was dehydrocyclized as described in Example 1.

(2) A catalyst prepared as described above but omitting the sodium addition step was also tested under the same conditions.

The results were as follows. Example 3 The sodium-containing catalyst described in Example 2 was used for the cyclodehydrogenation of n-hexane to benzene under the operating conditions of Example 1 for 42 hours continuously.

The results obtained during this reaction were as follows.

EXAMPLE 4 Several different commercially available dehydrocyclization catalysts were tested under the operating conditions of Example 1 and their activities and benzene yields compared to those of the sodium-containing catalyst described in Example 2. compared with.

The results are as follows. Example 5 A sodium-treated catalyst similar to Example 2 was prepared in a microreactor at a hydrogen to hydrocarbon ratio of 6:1 and 1 v/v.
It was used to hydrogenate benzene at various temperatures under atmospheric pressure at a liquid hourly space velocity of /hr.

Instead of reducing at 500'C for 2 hours, it was reduced at 250°C for 30 minutes.

The following transformations were achieved.

Example 6 A catalyst similar to that of Example 5 was tested under the same conditions and
It was used for hydrogenation of benzene at 5°C.

In this example, the catalyst was reduced for 1/4 hour at 225°C. The following transformations were achieved.

Example 7 Example 5 was repeated using a reformed catalyst containing 0.35% Pt on commercially available alumina that was reduced at 250°C for 11/2 hours.

The following transformations were achieved.

Example 8 Example 7 was repeated using a reformed catalyst containing 0.35% Pt on commercially available alumina that was reduced at 500°C for 11/2 hours.

The following transformations were achieved.

It will be noted that all hydrocarbon conversions were carried out in a microreactor with a catalyst capacity of 0.45 ml.

This volume corresponds to the graphite-containing carbon-based catalyst 0,
2257, corresponding to 0.45f of the alumina-based catalyst. To ensure a comparison of the platinum content in the reactor, it is necessary to load the carbon-based catalyst with twice the platinum content of the alumina-based catalyst. Example 9 Noritz Clydesdale Limited (N
OritClydesdale Ltd. A sample of activated carbon sold under the trade name NOritExtra by
It was heated at 0°C to partially graphitize.

This material had partially disintegrated. That is, its total surface area has been significantly reduced. The 27 was then oxidized by heating at a temperature of 450° C. for 5 hours in air flowing at a rate of 50 ml/min to increase the surface area.

The following results were obtained. BET surface area before oxidation: 740m
”/y BET surface area after oxidation 13507T1/tBasic surface area before oxidation 169m”/y Basic surface area after oxidation 43
0771"/t Edge surface area before oxidation 2.5 m"/V Edge surface area after oxidation 35 m"/1 Final BET/base ratio 3:1 Final base/edge ratio 12:1 Total The weight loss was 13.7%.

The pH was 7. Example 10 A sample of activated carbon sold by WimbOlTle Chemicals Ltd. under the trade name SASCl3 was treated as in Example 9.

The difference was that the first heat treatment was performed at 1900° C. in an argon atmosphere. The results listed in the following table were obtained. Example 11 KetjenCa
rbOnN. V. Activated carbon sold under the trade name KetjenECl6 from ) was treated as in Example 9.

The results obtained are shown in the following table. Example 12 BRITAIN SECA COMPANY LIMITED.
tissueCecaCO. Ltd. ) from trademark name anti
AntiCarbOneA 40 (AntiCarbOneA
Activated carbon sold as C4O) was treated as in Example 9.

The results obtained are shown in the following table.

Example 13 Experiment showing the effect of properties of carrier carbon on catalytic activity Comparative tests were conducted on three types of carrier graphite-containing carbon whose surface properties were within and outside the specifications of the present invention.

Three types of heat treatments were performed on activated carbon sold as AC4O.

13-1, heated to 900℃ in argon, then heated to 4 in air.
Heated at 50°C for 5 hours.

Heat treatment was carried out in the same manner as in 13-2 and 13-1, and then the sample was heated to 1500°C in an inert gas.

Heat treatment was carried out in the same manner as in 13-3 and 13-1, and then the sample was heated to 1700°C in an inert gas.

A 0.7% platinum-supported catalyst was prepared using the three types of carbon thus obtained, filled in a microreactor, and n-hexane and hydrogen were introduced to perform dehydrogenation cyclization.

Reaction conditions: Displaying reaction results: The results are as follows.

Carbon No. 13-1 was only heated at 900° C. and was an unspecified carbon having a base plane surface area/edge surface area of 5 or less, and was shown to have poor catalytic performance and poor benzene yield.

Example 14 Experiment of Dehydrogenation Reaction Heat-treated carbon was prepared using the raw material of Black Pearls 2, which was used in Example 2.

Claims (1)

[Claims] 1 Consists of a carrier and a catalyst whose main component is 0.01 to 10% by weight of an active component of a platinum group metal, with or without a catalyst modifier, and the carrier has a basic planar surface area of at least 100% by weight.
m^2/g, the ratio of BET surface area to basal planar surface area is less than or equal to 5:1, and the ratio of basal planar surface area to edge surface area is at least 5:1. Catalysts for hydrogenation, dehydrogenation and dehydrocyclization.