JP2934861B1 - Method for recovering hydrogen from aliphatic amine compounds - Google Patents

Abstract

Abstract: PROBLEM TO BE SOLVED: To provide a treatment method capable of generating hydrogen at a high selectivity in the decomposition of an aliphatic amine compound as a malodorous substance and recovering it as hydrogen gas. SOLUTION: A method for recovering hydrogen from an aliphatic amine compound in which an aliphatic amine compound is decomposed by low-temperature plasma in an inert gas atmosphere to generate hydrogen at a high selectivity.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating an aliphatic amine compound which efficiently decomposes an aliphatic odor compound, which is a malodorous substance, and generates and recovers hydrogen with a high selectivity.

[0002]

2. Description of the Related Art In the treatment of volatile organic compounds having an odor, the odor is eliminated by decomposition and removal. In this treatment, if it is assumed that the decomposition products are collected and can be used as other energy, etc. as well as simply eliminating the smell, it is thought that this not only contributes to environmental problems but also leads to effective use of resources. .

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a processing method capable of generating hydrogen at a high selectivity and recovering it as hydrogen gas in the decomposition of an aliphatic amine compound which is a malodorous substance. .

[0004]

Means for Solving the Problems The present inventors have studied low-temperature plasma decomposition of organic compounds under anaerobic conditions,
It has been found that hydrogen is generated with high selectivity when aliphatic amines are decomposed by low-temperature plasma. The present invention has been made based on this finding. That is, the present invention provides a method for treating an aliphatic amine compound, which comprises decomposing the aliphatic amine compound by low-temperature plasma in an inert gas atmosphere to generate hydrogen at a high selectivity.

[0005]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The decomposition reaction in the method of the present invention is as follows.
The reaction is performed using a low-temperature plasma plasma reactor, and the reactor is not particularly limited. As a reaction device, for example,
A ferroelectric pellet-filled low-temperature plasma reactor or the like can be used, and the dielectric constant of the ferroelectric is preferably 3,000 to 10,000 at room temperature. The input voltage is preferably between 5.0 and 8.0 kV. If the input voltage is too high,
The conductivity in the reactor becomes high and the reactor conducts, so that a so-called breakdown phenomenon may occur. In this state, microdischarge cannot occur in the reactor. The decomposition reaction in the method of the present invention can be performed at room temperature, and the reaction temperature is usually 25 to 2
6 ° C. (reaction near room temperature, usually 1-2
° C).

In the present invention, an inert gas (eg, nitrogen gas, argon gas, or the like) is used as a background gas, and the oxygen concentration in the background gas is preferably less than 1%. If the oxygen concentration in the background gas is high, hydrogen generated by the decomposition reaction becomes water, and the recovery rate of hydrogen gas may decrease. In the method of the present invention, the aliphatic amine compound to be treated is mixed with a background gas at a concentration of preferably 400 ppm or more, more preferably 500 to 2,000 ppm, as a reaction gas, and the reaction gas is introduced into the reactor. The reaction gas pressure is preferably normal pressure (1 atm). The reaction gas flow rate can be arbitrarily selected without affecting the decomposition rate as long as the gas residence time is at least seconds.

The aliphatic amine compound which can be treated by the method of the present invention may be any compound as long as it is volatile, and any of primary, secondary and tertiary amines can be treated. A tertiary amine having a large number of hydrogen atoms per molecule is preferred from the viewpoint of large recovery. Also,
Aliphatic amine compounds having 1 to 6 carbon atoms are preferred,
6 is more preferred. Specifically, for example, methylamine,
Examples thereof include dimethylamine, trimethylamine, dimethylethylamine, methyldiethylamine, and triethylamine.

[0008] Methane is the next largest product of decomposition as a decomposition product in the treatment method of the present invention.
By appropriately selecting conditions such as ic Energy Density (SED) and the amount of power consumed per unit gas processing volume), hydrogen can be generated and recovered at a selectivity about four times that of methane. It is. Separation and recovery of generated hydrogen
It can be performed by a conventional method. In ordinary chemical reactions, when the severity of the reaction increases, secondary decomposition and side reactions of the target substance tend to occur.However, in the method of the present invention, the decomposition rate of the aliphatic amine compound is reduced by performing the decomposition reaction by low-temperature plasma. When the value is increased, the selectivity of the target hydrogen is also improved, and there is an excellent feature that hydrogen can be generated at a high selectivity without generating secondary contaminants due to side reactions and the like.

[0009]

Next, the present invention will be described in more detail with reference to examples. Examples 1 and 2 Barium titanate (BaTi) having a dielectric constant of 5,000 at room temperature
O ₃ ) (particle diameter 1 mm) packed in a low temperature plasma reactor packed with ferroelectric pellets (distance between electrodes 1.54 cm) at room temperature using trimethylamine (TM)
A) or dimethylamine (DMA) decomposition treatment was performed. An AC voltage of 50 Hz was applied between both electrodes, and the power consumption on the primary side was measured with a digital power meter. The SED was calculated from the ratio between the power consumption and the gas flow rate. A dry nitrogen gas was used as a background gas, and a reaction gas having a TMA or DMA concentration of 500 ppm was used. The gas flow rates were 0.5 L / min (gas residence time 8.9 seconds), 1.0 L / min (4.4 seconds) and 1.5 L / min, respectively.
L / min (3.0 seconds). The product was identified by GC-MS (Shim) equipped with a capillary column (DB-1).
adzu GC-MS 5050A). Quantitative analysis was performed on aliphatic amines and organic by-products with relatively high melting points by FI
GC (GL Science) equipped with D (flame flame ionization detector)
s, GC-353, Pora PLOT Amines), G for the C ₂ or less hydrocarbons with a FID and TCD (thermal conductivity detector)
C (Shimadzu GC-9A, Porapak Q + N, Molecular Sieve
13X). Quantification of H ₂ was determined by GC with TCD.
(Shimadzu GC-14B, Molecular Sieve 13X).

FIGS. 1 and 2 show graphs of the decomposition rates of TMA and DMA with respect to SED, respectively. Regarding the decomposition rate of any of the amines, the influence of the gas flow rate was not observed.
The decomposition rate increased with the ED value, indicating a high decomposition rate. It is assumed that even when the gas residence time is about 3.0 seconds, the energy transfer from the fast electrons to the aliphatic amine occurs sufficiently. There was almost no difference in the degradation rate with the number of alkyl substituents on the amine. For all amine compounds, hydrogen, methane, ethane, ethylene, and acetylene were obtained as decomposition products, and trace amounts of N ₂ O and the like were generated. Also, graphs of the selectivity of decomposition products (hydrogen, methane, C ₂ hydrocarbons) with respect to the amount of reaction hydrogen are shown in FIGS. 3 and 4, respectively. In any case, the higher the decomposition rate of the aliphatic amine, the higher the selectivity of hydrogen is, and the hydrogen can be generated with a selectivity about four times that of methane, which produces the next largest amount of hydrogen. Was. The maximum yield of hydrogen gas is TM
A was 59% and DMA was 57%. The selectivity of hydrogen, methane and C ₂ hydrocarbon was calculated based on the hydrogen balance. For example, in the case of TMA, the following equations (1) to (3) are used.

Equation (1) Select _H2 = 100 × (2 × Concn _H2 ) / [Initial concn _TMA × (Conv _TMA / 100) × 9] Equation (2) Select _CH4 = 100 × (4 × Concn _CH4 ) / [ Initial concn _TMA × (Conv _TMA / 100) × 9] Equation (3) Select _C2 = 100 × (6 × Concn _C2H6 + 4 × Concn _C2H4 + 2 × Concn _C2H2 ) / [Initial concn _TMA × (Conv _TMA / 100) × 9] (Select is selectivity, Concn is production concentration, Conv is conversion rate,
Initial Concn means initial concentration)

Example 3 Methylamine (MA) was prepared in exactly the same manner as in Examples 1 and 2.
(MA concentration in the reaction gas is 500
ppm). The reactivity of MA is almost the same as DMA,
At a SED of 12.1 kJ / L, a decomposition rate of 78 mol% was exhibited, and hydrogen gas could be recovered with a yield of 56%.

[0013]

According to the method of the present invention, it is possible to efficiently decompose an aliphatic amine compound, which is a malodorous substance, and to generate hydrogen at a high selectivity. Can be used. In the method of the present invention, by using low-temperature plasma, the higher the decomposition rate of the aliphatic amine compound, the higher the selectivity of hydrogen in the product is, and the higher the selectivity without generating secondary contaminants due to side reactions and the like. Hydrogen can be produced at a high rate.

[Brief description of the drawings]

FIG. 1 is a graph showing the decomposition rate of TMA with respect to SED in Example 1.

FIG. 2 is a graph showing the decomposition ratio of DMA to SED in Example 2.

FIG. 3 is a graph showing the selectivity of hydrogen, methane, and C ₂ hydrocarbons with respect to the amount of reactive hydrogen during TMA treatment in Example 1.

FIG. 4 is a graph showing the selectivity of hydrogen, methane, and C ₂ hydrocarbons with respect to the amount of reactive hydrogen during DMA processing in Example 2.

Claims (1)

(57) [Claims] 1. A method for recovering hydrogen from an aliphatic amine compound, comprising decomposing the aliphatic amine compound by low-temperature plasma in an inert gas atmosphere to generate hydrogen at a high selectivity.