JPH0468978B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field of the Invention) The present invention relates to a catalyst in which a component mainly containing rhodium is supported on silica. Currently, in the chemical industry, attention is paid to the usefulness of heterogeneous catalysts supported on noble metals, and a wide range of research and development is being conducted on oxidation and reduction reactions of group metals such as Mo and W. Silica carrier is different from other inorganic porous carriers, especially alumina, titania, etc., and is an inert carrier.
It is known as a heterogeneous carrier that does not exhibit SMSI effects, and is widely used as a carrier that fully brings out the performance of noble metals. Hydrogenation of olefins, hydrogenation of carbonyls, nuclear hydrogenation of aromatics _, dehydration reactions _, carbonylation as a step in the synthesis of oxygen-containing compounds under high pressure conditions. It is also used for oxidation and reduction, and occupies an important position as a catalyst. The present invention relates to an industrially useful rhodium-supported silica catalyst, which makes rhodium, which is limited in nature, highly dispersed and supports it effectively without waste, making it extremely effective for various hydrogenation reactions. It is expected that it will become a catalyst. (Description of prior art) Among supported metal catalysts, there are many catalysts that have been improved using specific supports to produce better products.
There is a reaction in which hydrocarbons are hydrogenated and reformed by adding such substances. (Recent patents include JP-A-60-
112888, JP-A-60-105636, JP-A-60-54735,
As a catalyst using a silica carrier (Japanese Patent Application Laid-open No. 60-27646, etc.), an oxidation catalyst containing Pd as the main component (Japanese Patent Application Laid-open No. 60-27646, etc.)
-87857). Furthermore, as a silica catalyst containing Rh as a main component, there is a catalyst for fuel gas production (Unexamined Japanese Patent Publication No.
-112840), low-temperature fuel catalyst (Japanese Patent Application Laid-open No. 58-14948)
is disclosed. Furthermore, silica carriers are often used in gas phase reactions to synthesize oxygen-containing compounds from synthesis gas. The objective is to be achieved by using a very specific carrier that has a peak at a specific pore size. In addition, as seen in JP-A-57-194044, high dispersion was achieved by thermal decomposition of acetylacetonate salt in an oxidized state, and JP-A-52-142689 was developed to achieve high dispersion using a non-aqueous organic solvent. We can see some ingenuity in the law. However, these methods do not necessarily give good results with the rhodium-containing silica carrier of the present invention, and it has not yet been possible to establish a general method for achieving high dispersion. Further, the metal alkoxide method is one of the methods for achieving high dispersion and is useful, but it requires a large number of steps and is far different from the simplicity of the present invention. The ion exchange method is also widely used as a highly dispersed catalyst preparation method, but it has many practical problems, such as contamination of the raw material salt with ammine complexes and extremely weak adsorption onto the silica carrier. (Simplified explanation of the invention) Here, the present invention provides a silica catalyst containing rhodium as a main component, in which the silica support used has (i) _a specific surface area of 20 m ² /
(ii) Hg ^intrusion method (contact angle 140°, surface tension
The pore volume measured at 480dynes/cm) is
(iii) The pore volume with a pore diameter of 36 Å to 75 Å is in the range of 0.110 cc/g or more and 1.8 cc/g or less.
By using a silica carrier with physical properties of 0.110cc/g or more and impregnating it with 6.0% by weight or less of rhodium, a highly dispersed rhodium catalyst that could not be achieved with a carrier that does not have the above physical properties can be achieved. It became possible to manufacture This goal was made possible by combining a silica carrier with many small pores with the simplest impregnation method. (Description of the invention) First, as a catalyst containing rhodium, catalysts to which co-catalysts other than rhodium are added are also effective, but generally they contain 6.0% by weight or less of Rh, and Rh is in the form of metal or 3% by weight. It can be used as a subvalent rhodium salt or complex. As promoters, Mn, Mg, Sc, Ir, Zr, Hf,
Mo, W, U, Th, etc., and alkali metals or alkaline earth metals such as Na, K, Li, Cs, Rb, Ca,
It may also contain St, Ba, etc. Furthermore, any of the lanthanide and actinide series elements can be used as the rare earth element. Compounds used as cocatalysts include inorganic acid salts such as halogenates, sulfates, nitrates, and carbonates, and organic acid salts such as oxides, hydroxides, acetates, formic acids, and oxalates. can be used. However, compounds soluble in water or other suitable catalysts are preferably used to facilitate the loading of these catalyst components onto the carrier. The amount of co-catalyst added is preferably such that the atomic ratio with rhodium is generally (co-catalyst)/Rh≦1.0. As a support, (i) the specific surface area measured using N ₂ gas is 20
m ² /g or more and 800m ² /g or less, and (ii) Hg press-in method (contact angle 140°, surface tension
The pore volume measured at 480dynes/cm) is
(iii) a pore volume with a pore diameter of 36 Å to 75 Å;
A silica carrier having physical properties of 0.110 cc/g or more is used. The preparation method is to dissolve the rhodium and, in some cases, a co-catalyst in water or an organic solvent such as n-hexane, alcohol, or acetone, add a carrier to this solution, and support the rhodium by a conventional impregnation method. , reduction or heat treatment, it is possible to obtain a supported and fixed target object. In particular, by drying at a low temperature, it becomes possible to form better rhodium particle sizes by further sufficiently evaporating the impregnating solvent. The catalyst components may be supported on the carrier at the same time, or each component may be supported on the carrier sequentially, or each component may be supported by reduction, heat treatment, etc. as necessary. While processing,
Techniques such as sequential and stepwise loading methods can be used. The catalyst prepared by the above method is usually subjected to a reduction treatment to activate rhodium to a substantially metallic state, and then subjected to a reaction. The reduction treatment is performed under hydrogen gas or under a mixed gas of hydrogen and carbon monoxide, or in some cases under hydrogen gas partially diluted with an inert gas such as nitrogen, helium, argon, etc., or under the above mixed gas. be able to. The reduction treatment temperature is 100 to 600℃, preferably
Carry out at a temperature of 250-550°C. At this time, in order to maintain the activation state of each component of the catalyst in an optimal state, the reduction treatment may be performed while raising the temperature gradually or stepwise from a low temperature. Further, the rhodium compound may be reduced by treatment with a reducing agent such as methanol, hydrazine or formalin. Hereinafter, the present invention will be explained in more detail with reference to Examples.However, in order to make it easier to understand the present invention, these examples are purposely shown under unified conditions, and the present invention is not limited to these examples. Therefore, it goes without saying that there are no restrictions whatsoever. Example 1 Specific surface area 196m ² /g, average pore diameter (4v/s)
103 Å, maximum peak 95 Å, pore volume below 10 ⁴ Å
The silica support had physical properties of 0.726 cc/g, and the pore volume with pore diameters ranging from 38 Å to 75 Å was 0.218 cc/g. Figure 1 shows the pore distribution of silica carrier "A-1" having the above-mentioned physical properties, and Table 1 shows the physical properties and the ratio of Rh to adsorbed carbon monoxide (dispersion rate). XRD
(Cu-Kd), Rh particles were measured but were not detected. The catalyst preparation method is shown below. 23.4 g (50 ml) of the above silica carrier, 2.55 g of rhodium chloride hydrate (RhCl _{3.3H 2} O), 0.427 g of iridium chloride (IrCl _{4.H 2} O), manganese chloride (MnCl ₄ .
4H ₂ O) 0.040g, lithium chloride (LiCl) 0.026g
was added to 16 ml of a uniformly dissolved aqueous solution, uniformly impregnated, and air-dried at room temperature for 2 hours. At 30℃, 4 hours, 60
It was dried under reduced pressure in a rotary evaporator at ℃ for 2 hours, and then reduced with hydrogen at 450℃ for 2 hours. Example 2 The same preparation as in Example 1 was carried out using silica carrier "A-2" having the physical properties shown in A-2 in Table 1. The carrier used was 22.3 g (50 ml), and the aqueous solution was 19 ml. FIG. 2 and Table 1 show the physical properties of the silica carrier and the Rh dispersion rate. Comparative Example 1 Silica (Davison # ⁵⁷ silica) as shown in Table 1 and FIG. 3 was used. Carrier 20.0g (50
ml), and the procedure was the same as in Example 1 except that the aqueous solution was 23.0 ml. Comparative Example 2 As shown in Table 1 and Figure 4, silica (JGC Chemical)
E56C1 silica) was used. Carrier 25.9g (50ml)
The procedure was the same as in Example 1 except that the aqueous solution was 17.0 ml. 【table】

[Brief explanation of the drawing]

Figures 1 and 2 are carriers of the present invention (Examples 1 and 2)
3 and 4 show the pore distribution of the carriers of Comparative Examples 1 and 2. In addition, the vertical axis of the drawing represents the pore density product (integral value cc/gA.U.), and the horizontal axis represents the pore diameter (AU).

Claims (1)

[Claims] 1 (i) The specific surface area measured using N ₂ gas is
20 m ² /g or more and 800 m ² /g or less, and (ii) Hg intrusion method (contact angle 140°, surface tension
The pore volume measured at 480dynes/cm) is
(iii) a pore volume with a pore diameter of 36 Å to 75 Å;
Rhodium is a catalyst component containing rhodium on a silica carrier having physical properties of 0.110cc/g or more.
A method for producing a rhodium-containing catalyst, which comprises impregnating and supporting the rhodium-containing catalyst to a content of 6.0% by weight or less.