NL8600646A - Catalyst with porous carrier contg. silica - carrying layer of carbon and layer of catalytic metal - Google Patents

Abstract

A catalyst consists of a porous carrier contg. SiO2, on which have been deposited w.r.t. 100 sq.m of internal specific surface, 0.2-0.5 g of C, and then 0.005-0.3 g of catalytic metal w.r.t. 1 g of catalyst. The carrier contains SiO2 and Al2O3, and is esp. SiO2/Al2O3 with Al2O3:SiO2 ratio 90:10-10:90 (75:25-90:10). The catalyst has BET surface of 75-450 sq.m/g, and contains a catalytic metal with atomic number 21-79, pref. Ni, Cu, Co, Pt or Pd. The internal surface of a porous carrier contg. SiO2, with specific internal surface of 70-450 (150-300) sq.m/g is coated with a thin layer of C, and then with the catalytic metal.

Description

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It is generally known to use a porous SiOj-containing material as a support for catalysts.

As such, especially guhr, silica # amorphous alumina silicas and silica alumina as well as clay minerals are used. These carriers generally have a BET total surface area of at least 100 µg / g.

It has now been found that if a catalytic metal such as e.g. nickel # cobalt # 10 copper or iron causes metal-carrier interactions to occur which attack or nullify the activity of the catalyst. For example, inactive metal silicates or metal hydroxysilicates or other reactions with the internal surface may optionally take place.

It is true that various inert carriers are known, but as a rule these have a very low specific BET surface area of only a few m / g (e.g. TiO2 or 20 carborundum) or the carrier material is microporous as e.g. active carbon while on the other hand pyrolytic carbon - which is obtained by e.g. pyrolysis of polymers if polyvinyl chloride has an unsuitable texture.

It has now been found that certain new catalysts have high activity and long life for e.g. hydrogenating organic compounds or desulfurizing hydrocarbons. These new catalysts consist of a porous SiO 2 -containing support material with a BET surface area between 75 and 450 m / g on which per 100 internal specific surface area an amount of 0.2 to 0.5 g carbon and subsequently 0.005 to 0.30 g metal per g catalyst is applied.

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Preferably the starting support material contains both S1O2 and AI2O3 and more particularly it is an alumina silica or a silica-alumina with an oxide ratio between 90/10 and 10/90, most preferably between 75/25 and 90/10 (AI2O3 / S1O2) · Sometimes it has the advantage to use acid-activated carrier material.

As the metal, the catalyst generally contains a metal whose atomic number is from 21 to 79 and preferably the metal is a transition metal such as e.g.

cobalt, nickel, copper, platinum or palladium or mixtures thereof. After coating with carbon and applying metal, the finished catalyst generally has an internal surface area between 75 and 450, preferably between 150 and 400 m / g.

Both the application of the carbon coating and the application of the catalytically acting metal can be carried out by various techniques: The carbon coating can be applied by pyrolysis of an organic compound in the presence of the carrier. The porous structure of the inorganic support determines the porous structure of the final support, provided that the pyrolysis is carried out at a sufficiently low temperature.

1. The coating can be applied by impregnating the support with an aqueous solution of a suitable organic material, e.g. surface active agents: a polyoxyethylene alkyl ether an alkali metal soap an alkyl benzene sulfonate an alkyl (benzene) phosphonate 35 an alkylamine (cxo-c18 ^

General: nonionics, anionics, cationics or a mixture thereof, whether or not combined with other compounds.

2. - The coating can be applied by the carrier • * »S -V f.

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3. The coating can also be applied by impregnating the support with a non-volatile organic compound or a non-aqueous solution of a non-volatile organic compound or polymer such as - triglyceride - polybutadiene - polystyrene IS. After this impregnation, the support is calcined at 120-600 * C, if possible in air or else in one. inert atmosphere such as nitrogen, after which the organic phase in the porous support pyrolyses and carbon is deposited on the internal surface. If necessary, several impregnations are carried out optionally before or after calcination.

4. The coating can be applied by passing an unstable gas at a high temperature over the support, depositing carbon as a result of pyrolysis. Suitable gases are: ethylene, propylene, butene, butadiene, benzene, etc. This technique is described, inter alia, in US-A-4 018 943. The pyrolysis temperature is determined by the stability of the chosen compound and will be between 350 ° C and 850eC. .

On the support material, according to one of the above-mentioned techniques or by a combination thereof, depending on the specific surface, 4-60% is used at ** v * «. ^ ~ v Λ J 41: c *; · ΰ - ** o

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- 4 - * - - R 7016 (R) preferably deposited from 10-40% carbon. Care should be taken to ensure that the internal surface is completely covered with the lowest possible carbon content. If the degree of coverage is too high, the pores are completely filled with carbon, which reduces the accessibility of the catalyst. At the same time, undesired micropores arise in the carbon layer. The support contains 0.2-0.5 grams of carbon per 100 m2 "internal specific surface (So with an internal specific surface 10 (SBET) 250 m2 / g, 0.4 grams of carbon and 1 gram of inorganic support there is therefore 28, 55¾ carbon; present). The thickness of the carbon layer ranges from 1.5 to .6, preferably 1.5 to 3.10 ~ 1 .mu.m.

Then a catalytically active metal or metal combination is applied to the thus carbon-coated support. The metal can be applied by known catalyst preparation methods, such as: - pore volume impregnation with an aqueous solution of a suitable metal salt.

- pore volume impregnation with an ammoniacal retal solution (e.g. nickel). During drying, ammonia is boiled out, after which metal compounds precipitate.

- pore volume impregnation with a urea-containing solution of the metal. During drying, urea is decomposed after which metal compounds precipitate on the internal surface of the support.

- Precipitation of metal compounds from a suspension of the support in an ammoniacal metal solution (e.g. nickel), by boiling out ammonia.

Subsequently, the coated, impregnated carrier is dried, if necessary calcined (usually in an inert atmosphere) and activated, e.g. by reduction.

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The finished catalyst usually contains between 0.5 and 30% metal and has a crystallite size between 1 and 5 nanometers. The catalyst thus obtained was found to be very suitable, especially in terms of activity and life, for the hydrogenation of organic compounds, in particular unsaturated oils and fats. This catalyst also proved to be very suitable for desulphurizing hydrocarbons such as petroleum and fractions thereof.

IQ The application is illustrated by the following examples:

Example I

Amorphous silica, PV = 1.7 ml / g, sBET = 270 m2 / g was impregnated with an aqueous solution containing 59% sucrose. The impregnated silica was dried at 100 ° C and then calcined in air at 250 ° C for 2 hours. After this treatment, the support contained 30% carbon. The support thus obtained was impregnated with an ammonia solution of cobalt hydroxy carbonate by the technique of pore volume impregnation. The resulting catalyst was dried at 100 ° C and then calcined at 400 ° G for 1 hour under N2 atmosphere. After sulfidation at 350 ° C in an atmosphere of 90% H 2 and 10% HjS, the resulting catalyst was markedly more active in the desulfurization of thiophene at 350 ° C and 10 atmosphere H 2 than a corresponding catalyst prepared on the silica without carbon coating.

Example II

The same coated support from Example I was impregnated with an ammoniacal solution of nickel carbonate and dried at 100 ° C. The thus

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The catalyst obtained was reduced in an atmosphere of hydrogen at 400 ° C for half an hour at 400 ° C and was more active in the hydrogenation of unsaturated organic compounds than a corresponding catalyst prepared on the uncoated silica.

Example III

Amorphous silica-alumina 85/15 (S * ° 2 / A12 ° 3 ^ 10 Sbet = 440 m ^ / g was dehydrated at 500 ° C for 1 hour. The heat-treated silica-alumina was now impregnated with a solution of 50% glucose in water and the impregnated support was dried at 120 ° C. After drying, the impregnated support was calcined in air at 250 ° C for 1 hour. The thus carbon-coated support was impregnated with an ammonia solution of cobalt hydroxy carbonate and then dried at 100eC, then calcined for 1 hour at 400eC under a nitrogen atmosphere The finished catalyst was activated in an atmosphere of 90% Hj and 10% at 350 ° C for 20 hours and was used to desulfurize a mixture consisting of 90% toluene, 1 1.5% thiophene, 1.5% pyridine and 7% cyclohexane, at 350 ° C and 10 atm H 2 · The catalyst was found to be considerably more active than a catalyst prepared on the uncoated amorphous silica-alumina.

Example IV

The coated support from example III was impregnated with the same ammonia solution of nickel carbonate and then dried at 100 ° C. The catalyst thus obtained was temperature reduced in a programmed manner (delta T = 2eC / min.Tmax. = 400eC) and this maximum temperature was maintained for half an hour. The catalyst was considerably more active in the hydrogenation of unsaturated organic compounds (such as soybean JQ U 0 4 9 ♦ R 7016 CR)! Oil and benzene) is a catalyst prepared on the uncoated amorphous silica-alumina.

Example V 5

The silica from Example I was impregnated with a solution consisting of 1 part of polyoxyethylene alkyl ether and 2 parts of water. The impregnated support was dried at 100 ° C and then calcined in air at 200 ° C for 1 hour. The calcination temperature was increased to 350 ° C using the N2 as an inert atmosphere.

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The coated support was impregnated with an ammoniacal solution of nickel carbonate; dried at 100 ° C and calcined at 400 * C under an inert atmosphere. The finished catalyst was sulfurized with 10% H 2 S in H 2 at 350 ° C and used to desulfurize the mixture as specified in Example III. The catalyst was considerably more active than a catalyst prepared on the uncoated silica.

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Claims (14)

1. Catalyst consisting of a porous SiO2-containing support material to which an amount of 0.2 to 0/5 g of carbon and subsequently 0.005 to 0.3 g of catalytic metal per gram of catalyst is applied per 100 m 2 of internal surface area. Catalyst according to claim 1, characterized in that the support contains both SiO 2 and Al 2 O 2. Catalyst according to claim 1 or 2, characterized in that the support is an alumina-silica or a silica-alumina with an Al2O2 / SiO2 ratio between 90/10 and 10/90, preferably between 75/25 and 90/10. Catalyst according to claim 1, 2 or 3, characterized in that it has a BET total surface area between 75 and 450 m / g. Catalyst according to any one of claims 1 to 4, characterized in that the catalytic metal has an atomic number between 21 and 79. Catalyst according to claim 5, characterized in that the metal used is nickel, copper, cobalt, platinum or palladium. Method for coating the internal surface of a porous SiO2-containing support material with a layer of carbon, characterized in that the specific internal surface of the support material is between 70 and 450 m ^ / g, preferably between 150 and 300 m ^ / g, the amount of carbon applied is between 0.2 and 0.5 g per 100 m 2 internal surface area, and subsequently applied to the coated support 0.005 to 0.3 g of catalytic metal per gram of catalyst. fs Λ £ /. £ ï 0. U v - 9 -, -R 7016 (R) * 8. A method according to claim 7, characterized in that the support is an alumina-silica or a silica-alumina with an SiO2 ratio between 90/10 and 10/90, preferably between 75/25 and 90/10. 9. A method according to claim 7 or 8, characterized in that the SiO 2 -containing carrier is pre-activated with suction. Method according to claims 7, 8 or 9, characterized in that a layer of carbon is applied by impregnation with an organic compound followed by pyrolysis. c ft A method according to claim 10, characterized in that the carbon coating is applied by impregnation with a carbohydrate followed by pyrolysis. Method according to any one of claims 7 to 10, characterized in that the catalytic metal is applied by impregnation. Process for the hydrogenation of unsaturated organic compounds, characterized in that a catalyst according to any one of the preceding claims is used. A method for desulfurizing hydrocarbons by treating them at elevated temperature in the presence of hydrogen with a catalyst according to any one of claims 1 to 12. r. *> λ · \> • '· ·; ! . , Y y 'V »