JPS5842235B2 - Odorizing agent for fuel gas - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an odorant for fuel gases such as liquefied natural gas (LNG) and city gas, and particularly to an odorant for fuel gases that is effective in small amounts.

The purpose of the present invention is to achieve a remarkable odor-adding effect even on liquefied natural gas that does not contain sulfur.
It is characterized by containing cyclohexene alone or as an essential component.

Currently, in order to prevent disasters such as poisoning and explosions, fuel gas (city gas or LPG) is added with a substance that has a unique odor so that it can be easily detected by the human sense of smell in the event of a gas leak.

Traditionally, sulfur compounds (mercaptans, sulfides, etc.) have been used as these unique odor components (odorants), but as liquefied natural gas (LNG), which does not contain sulfur, has become popular in Japan in recent years, There is a need for a gas odorant that does not impair this property.

Several odorants have already been developed for this purpose, but none of them can be said to be ideal.

As a result of intensive research into the suitability of non-sulfur compounds as odorants, the present inventor found that any composition containing cyclohexene alone or as an essential component is more effective than sulfides, which are conventionally used as odorants. The inventors have discovered that this gas has a high odor-adding effect, and that it actually gives off an extremely strong gas odor, leading to the development of the present invention.

When cyclohexene is used alone, the perceived concentration is 30
~40 γ/, l, compared to the perceived concentration of conventional sulfides of 1i60 γ/m, it can be seen that it is perceived at a lower concentration and has a greater odor-adding effect.

Furthermore, when conventional mercaptans or (and) sulfides are mixed with cyclohexene, a synergistic odor effect is produced resulting in an extremely strong gas odor, and gas leakage can be detected even with the addition of a very small amount.

Examples of mercaptan include ethyl mercaptan, isopropyl mercaptan, and t-butyl mercaptan, and examples of sulfides include dimethyl sulfide, methyl ethyl sulfide, and methyl ester sulfide.

By mixing these mercaptans or (and) sulfides, the perceived concentration becomes 10[gamma]/-, making it possible to obtain an odorant with an even greater odorizing effect.

More specifically, the synergistic effect of the above-mentioned mixing can be obtained by mixing 0.1 to 10% of mercaptan or/and sulfide alone or in a mixture thereof with cyclohexene.

Note that the perceived concentration here refers to a specified odorant substance that is diluted with air in an odor-free room, and six trained panelists evaluate the odor using the six-level odor display method shown in Table (I). It is expressed as the concentration of an odorant substance in an odorless room with a strength of 2.

The results of a test conducted to clarify the odor intensity of the odorant in the present invention are shown in the figure.

In the figure, the vertical axis represents the average odor intensity of six panelists, and the horizontal axis represents the odorant concentration in the odorless room.

The broken line A in the figure represents the odorant concentration and odor level when 95 parts of cyclohexene and 5 parts of t-butyl mercaptan are mixed.

The three-dot dashed line B represents the case when 95 parts of cyclohexene is mixed with 5 parts of t-amylmercaptan, the two-dot dashed line C represents the case with dimethyl sulfide, and the dotted line represents the case where 5 parts of dimethyl sulfide is mixed with 95 parts of cyclohexene, and the solid line E represents the relationship between the concentration of each substance and the degree of odor when cyclohexene is used alone.

As shown in the figure, a mixture of cyclohexene and mercaptan or sulfide has an extremely effective synergistic effect, resulting in a perceived concentration of 10γ/-, which is 6 times lower than the perceived concentration of dimethyl sulfide, 60γ/7y23.
It is found that the odor-adding effect is high.

Regarding odorants for city gas, it cannot be said that they are truly excellent odorants simply because they have an odor-adding effect; they are water-soluble, adsorbable to soil, adsorbed by iron rust, odor attenuation inside iron pipes, and resistant to metals. Corrosion, swelling to rubber, backing, etc., toxicity,
Masking, etc. must also be considered.

In this respect, cyclohexene has better properties than tetrahydrothiophene (THT), which has been used in conventional city gas.

Table (1) compares its suitability as an odorant with tetrahydrothiophene (THT).
Better than T.

Examples of the present invention are shown below, but the present invention is not limited thereto.

Example 1 95 parts of cyclohexene to 5 parts of t-butyl mercaptan
Mix, stir, and dehydrate to obtain a product.

When this product was added to natural gas at 10 μ/d and released so that the gas concentration in the air was 1/200, a gas odor was clearly detected.

Example 2 95 parts of cyclohexene, 2.5 parts of isopropyl mercaptan and 2.5 parts of t-butyl mercaptan are mixed, stirred, and dehydrated to obtain a product.

When this product was added to natural gas at 10 μ/l and released so that the gas concentration in the air was 1/200, a gas odor was clearly detected.

Example 3 3 parts of allyl mercaptan to 95 parts of cyclohexene,
1 part of t-butyl mercaptan and 1 part of methyl ethyl sulfide are mixed, stirred, and dehydrated to obtain a product.

When 60 μg of Honjima was added to 1 kg of LPG and released so that the gas concentration in the air was 17,200, a gas odor was clearly detected.

[Brief explanation of drawings]

The figure is a graph showing the relationship between odorant concentration and odor intensity in an example of the present invention.

Claims (1)

[Claims] 1. An odorant for fuel gas containing cyclohexene alone or as an essential component.