JPH088988B2 - Coating layer and method for producing the same - Google Patents

Description

TECHNICAL FIELD The present invention relates to a coating layer of Ce _q Cu _r Mn _s O _z having a catalytic action for oxidative decomposition of hydrocarbon compounds and a method for producing the same.

2. Description of the Related Art Conventionally, for the oxidative decomposition of hydrocarbon compounds, especially triglycerides of higher fatty acids such as oil stains found in cookers, there is a method of directly thermally decomposing at about 500 ° C. and Mn, Co, Cu, Ni, F
There has been a method of oxidative decomposition at a temperature lower than 500 ° C using a transition metal oxide such as e as a catalyst. However, with conventional metal oxides, the activity is low and a temperature of 400 ° C or higher is required to completely oxidize and decompose triglyceride, and by using it as a coating layer containing a catalyst, the catalyst surface is covered with a binder. The activity is further reduced.

On the other hand, the method for forming the coating layer is to immerse the porous carrier in a metal solution, pull up the carrier and carry out thermal decomposition to directly support the metal oxide, and further synthesize the metal oxide in advance and disperse this in the binder. There are mainly two types of coating methods in which a coating layer is formed by drying and baking after coating on a carrier.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-mentioned conventional techniques, the activity of the coating layer containing the catalyst is low, the loading method is large in the direct method in forming the coating layer, and the harmful gas at the time of thermal decomposition is There is a problem that the catalyst surface is covered with the binder in the coating method because the generation (for example, NO ₂ ) may occur and it may be difficult to obtain uniform particles during the thermal decomposition.

The present invention provides a coating layer and a method for producing the same that solve the above problems.

Means for Solving the Problems In order to solve the above problems, the present invention provides SiO ₂ , Al ₂ O ₃ , and ZrO.
Co, Cu, Mn coprecipitated with alkali on a porous film consisting of one or more oxides of ₂ and TiO ₂ and pyrolyzed to form a complex oxide Ce _q Cu _r Mn _s O _z It is to be carried.

Action By the above technical means, catalyst (composite oxide) Ce _q Cu _r Mn _s O
It becomes possible for _z to be supported on the porous membrane without covering the surface with other substances.

Ce _q Cu _r Mn _s O _z shows higher activity for the oxidation of triglyceride than the single oxides of each component. For example CeO2 ₂ , CuO,
The oxidation activity is higher than any of Cu ₂ O, Mn ₂ O ₃ and MnO ₂ .
According to XPS, XRD data, etc., the valence of the element on the surface of the complex oxide has many values, that is, the valence is controlled between different elements and a surface suitable for the reaction is created. It is thought to be because they get it.

Further, according to the method for producing the coating, Ce _q Cu _r Mn _s O _z is SEM
It has been found by magnifying observation that the particles are uniformly dispersed in the pores of the porous membrane, the particle size is much smaller than 0.1 μm, and the surface is not covered with other substances. In this way, Ce _q Cu _r Mn _s O _z is dispersed with a very fine particle size, and a coating layer having high oxidation activity can be obtained. This is a method of generating a co-precipitate using an alkali on the porous membrane, and the process of forming the co-precipitate depends on the reaction of the ion size in the alkali. It is clear from the SEM observation image that the particle size does not increase to the maximum even if the particles are formed and thermally decomposed.

Example Hereinafter, an example of the present invention will be described.

In Ce _q Cu _r Mn _s O _z , using nitrates of each element so that q = 2, r = 1, s = 1, an aqueous solution containing 0.1 M of Ce, Cu, Mn in total and a 0.2 M aqueous solution of NaOH were prepared. Got ready. 50 mm x 50 mm for carrier
A size-wise metal plate with a porous film of SiO ₂ formed on both sides was used as a test piece. Ce, Cu, M support at room temperature
After immersing in an aqueous solution containing n, further immersing in an aqueous NaOH solution, after confirming that co-precipitation was formed, it was washed with water, dried and pyrolyzed, and then Ce _z CuMnO _z was supported on the SiO ₂ carrier. FIG. 1 is a schematic cross-sectional view of the coating layer after supporting Ce ₂ CuMnO _z . The SEM observation image of the coating layer thus obtained is Ce ₂ CuMnO _z
Showed a high dispersion of.

By the same method, MnO _x , CuO _x , and CeO _x oxides (where x is
> 0) is formed on the hot plate so that each test piece containing 4 oxides has the same area.
The mixture was kept at 360 ± 10 ° C., and commercially available salad oil was used as triglyceride. afterwards,
Following changes over time, the salad oil of Ce ₂ CuMnO _z completely disappeared within 1 hour, but the other ones had residue. Thus, the oxidative decomposition of salad oil by Ce ₂ CuMnO _z proceeds at a temperature of around 360 ° C. This is Ce ₂ CuMnO _z
It has a high oxidative activity and is dispersed as fine particles without covering the surface of the carrier.

On the other hand, with respect to MnO _x , CuO _x , CeO _x , Ce ₂ Cu, and MnO _z , powders and salad oil were mixed at a constant weight ratio, and the weight change of the salad oil due to temperature rise was followed using a thermobalance. The results are shown in FIG. It is clear from this that Ce ₂ CuMnO _z is more active than other oxides.

Next, in the general formula Ce _q Cu _r Mn _s O _z , q is changed at 0.5, 1.0, 2.0 and 5.0 with constant r = 1 and s = 1, and q = 2.0 and s =
It was made to have a constant r of 0.25, 0.5, 1.0, and 5.0, and the decrease in salad oil weight was traced using a thermobalance. According to this, a decrease in activity was observed at q = 5.0 and r = 5.0. At q = 5.0, 50% of salad oil at 400 ℃
Remained, and approached the curve of CuO _{x at} r = 5.0. Therefore, it is considered that the composition ratio is 5 or less for q and r for s = 1.

Next, a coating layer was formed by a coating method using Ce ₂ CuMnO _z powder. Using alumina sol as a binder, 20% by weight of Ce ₂ CuMnO _z was mixed with the alumina sol, and the mixture was applied onto a metal substrate to form a film. The film thickness was 20 μm. Using this test piece, the change with time of the salad oil was observed at 360 ° C ± 10 ° C on a hot plate as described above, but there was a residue.

The coating method is predominantly larger in the content of the catalyst, but it is considered that the exposed area of the surface, on the contrary, is less influenced by the binder. In addition, when the catalyst is used as powder, secondary and tertiary particle aggregation occurs and high dispersibility cannot be obtained.

Further, comparing the appearance of the coating layer thermally decomposed through coprecipitation with the coating layer directly pyrolyzed without coprecipitation, the latter was uneven and the former could be uniformly and evenly supported.

From the above points, the coating layer containing Ce ₂ CuMnO _z and the method for producing the same according to the present invention are suitable for the oxidative decomposition of triglyceride, and can be applied as the inner wall surface of a cooker or the like.

As described above, according to the present invention, a coating layer carrying Ce _q Cu _r Mn _s O _z having high oxidative activity against oxidative decomposition of higher fatty acids can be obtained, and its production method is Ce _q Since the fine particles of Cu _r Mn _s O _z can be uniformly and highly dispersed, triglyceride such as salad oil can be oxidatively decomposed on this coating layer. Therefore, if the coating layer is applied to the inner wall surface of the cooker, the inside of the cooker can be always kept clean.

[Brief description of drawings]

FIG. 1 is a schematic sectional view of a coating layer according to an embodiment of the present invention, FIG.
The figure is a thermogravimetric change curve diagram of salad oil using various oxides.

Claims (2)

[Claims] 1. Ce _q Cu _r Mn _s O _z A coating layer in which a composite oxide represented by the formula (1) is carried on a porous film made of one or more oxides of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , and TiO ₂ . _2. A coprecipitate is deposited from a solution containing Ce, Cu, Mn on a porous film made of any one or more oxides of SiO ₂ , Al ₂ O ₃ , ZrO ₂ and TiO ₂ and heat-treated. Decomposes to form a complex oxide Ce _q Cu _r Mn
_s O _z A method for producing a coating layer for producing and supporting the above.