JPH0977690A - Production of acetylene - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain acetylene from a methane-containing gas in a high selectivity by subjecting the methane-containing gas to a microwave plasma reaction under a specific condition to convert the methane into the acetylene. SOLUTION: A methane-containing gas is subjected to a microwave plasma reaction under the output of microwaves of >=100W, preferably 200-350W. An inert gas such as Ar or N2 is preferably used as a carrier gas. A microwave plasma reactor usually comprises a gas-charging section, a microwave-generating section and a reaction section. A reaction pipe is preferably a vertical reaction pipe from the viewpoint of the behavior of the plasma in the pipe. The microwave generated in the microwave-generating section is preferably projected on the reaction pipe through a horizontally disposed wave guide pipe. The gas of raw material is usually charged at a rate of 0.1-10mmole/min. The reaction pressure is usually 2-10kPa, and the reaction time is generally 0.1-10sec.

Description

Detailed Description of the Invention

[0001]

[0001] The present invention relates to a method for producing acetylene from a methane-containing gas.

[0002]

2. Description of the Related Art Various methods for synthesizing lower hydrocarbons other than methane from a gas such as methane or methane-containing natural gas have been proposed. For example, a method using a microwave plasma reaction has been proposed. The main purpose of this study is to study the production of

[0003]

However, when acetylene is intended, it is difficult to increase the selectivity of acetylene by the conventional method, although the conversion of methane can be improved. Therefore, the present inventors have conducted various studies to find a method that can improve the selectivity of acetylene, and have surprisingly found that this problem can be achieved by performing a microwave plasma reaction under specific conditions. ,
The present invention has been reached. That is, the present invention provides a gas containing methane under microwave power of 100 W or more in a microwave plasma reaction to obtain acetylene by converting the methane into acetylene. The manufacturing method is the main point.

[0004]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below.
First, in the present invention, examples of the gas containing methane as a starting material include methane gas and natural gas,
Methane content is not particularly uniform. When subjecting the gas containing methane to the microwave plasma reaction, it is preferable to use a gas inert to the reaction, such as Ar or N ₂ , as the carrier gas.

[0005] A reactor for performing a microwave plasma reaction includes a gas supply unit, a microwave generation unit, and a reaction unit.
The reaction gas introduced into the reaction section, which is a reaction tube that does not absorb microwaves, such as a quartz glass tube, having a feed gas adjusted to have a predetermined component ratio in the gas mixer is of a vertical type.
It is preferable from the viewpoint of observing the behavior inside the tube when plasma is generated.

It is preferable that the reaction section is irradiated with a microwave generated by a microwave generation section, for example, a microwave oscillator of 2.45 GHz through a horizontally installed waveguide to cause a plasma reaction. In the present invention,
When carrying out this plasma reaction, the microwave output is set to 1
It is necessary to set it to 00 W or more. Usually 100-400
W, preferably 200 to 350 W. 100W
When it is less than 1, the selectivity of acetylene is lowered and the conversion of methane is also lowered.

According to the present invention, the methane conversion is 75% or more and the acetylene selectivity is 85% or more, preferably 95%.
The above can be done. The supply of the raw material gas is usually 0.
The reaction pressure is about 1 to 10 mmol / min.
It is usually selected from about 2 to 10 kPa. Further, the reaction time is generally selected from about 0.1 to 10 seconds (irradiation time). The target product is separated from the reaction product derived from the reaction section by an ordinary method.

[0008]

The present invention will be described in detail below with reference to examples. Example 1 The ratio of methane (purity 99.2%) / Ar was changed and introduced into a microwave plasma reactor. The reaction tube is a vertical type made of quartz glass (inner diameter 22.3 mm, thickness 1.6 mm, length 3
A microwave of 2.45 GHz was generated at an output of 200 W, and the reaction tube was irradiated through a horizontally installed waveguide (cross-sectional area: vertical 54.5 mm, horizontal 108.7 mm). Reaction gas supply rate is 1.92 mmol / mi
n, and the reaction pressure was 7.5 kPa. The reaction products were analyzed by gas chromatography using a vacuum sampler. The yield of the reaction product was as follows.

[0009]

[Table 1] Output 200W Methane mole fraction 100% 80% 60% 40% 20% Methane conversion rate 83.3 85.8 81.6 65.2 58.5 Acetylene selectivity 96.3 95.9 96.0 73.9 40 Ethylene selectivity 2.3 2.1 2.6 1.8 0.3 Ethane selectivity 0.7 0.7 1.2 3.2 2.5 The amounts of C ₃ and C ₄ compounds produced were very small.

Claims (1)

[Claims] 1. Production of acetylene, characterized in that methane is obtained by subjecting a gas containing methane to microwave plasma reaction under microwave power of 100 W or more to convert the methane into acetylene. Law.