JPS5829243B2 - Hydrogen production method - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing hydrogen, and more particularly to a method for producing hydrogen using a reducing gas such as arsenic or arsenic.

Hydrogen is one of the important raw materials for Higaku Kogyo, and is in high demand. Process developments have significantly increased the demand for cheap, high-purity hydrogen.

Hydrogen synthesis is broadly classified into methods using water as a raw material and methods using carbon and arsenic as raw materials, but in recent years the latter has become the mainstream.

This method uses, for example, coal produced from the cracking of petroleum [
A mixture of arsenic and water vapor are reacted at around 800°C in the coexistence of a nickel catalyst or the like.

In this method, the reaction proceeds as exemplified by formula (1), and hydrogen is generated from the by-produced monoacid f carbon by the reaction of formula (2) at around 400°C.

C3H6+3H20→3 CO+ 6 H2O(1)3
CO + 3HO → 3H + 3CO (2> 2 2 2 However, this process requires high-temperature reaction conditions of 800°C, which requires high-grade materials such as heat-resistant steel for the equipment, and also Therefore, it is necessary to separate unreacted components, water vapor, carbon dioxide, etc. from the gas after the reaction is completed, making the process complicated.

In view of the above, the present inventors have discovered that C
We researched a method to produce high-purity hydrogen from O or carbon, arsenic, and water vapor.
Molybdenum (MO), tungsten (W), vanadium (V), uranium (U), iron (Fe), nickel (Ni), etc. with arsenide added with platinum group elements such as rhodium, platinum, palladium, ruthenium, etc. Transition metal acid f arsenide and 3
They discovered that when water vapor is introduced into the reduced acid (arsenic acid) at a temperature range of 00 to 500°C, it reacts quickly to generate hydrogen, and a separate patent application has been filed.

In the above method, the transition metal acid 1 arsenide is converted into CO or charcoal 1 arsenide.
It consists of step A of reducing with arsenic, and step B of applying water vapor to the reduced transition metal acid (arsenic) to make it into an acid [arsenic] state and simultaneously generating hydrogen. In metal acids (arsenic oxides), the oxide not only transfers electrons but also moves oxygen atoms, resulting in changes in volume and strength, and its physical properties as a solid substance change.

That is, the metal oxide employed in the above method is typically in the form of granules or pressure-molded pellets;
These particles undergo changes in mechanical properties, particularly particle pulverization and changes in mechanical strength, due to the above reaction.

By the way, in order to repeatedly perform two different reactions with one effector (metal oxide in this case), it is necessary to switch the reaction gas flow path or move the effector.
The latter method is not suitable because it promotes the above-mentioned particle dusting, and for this reason, a method in which the gas flow path is switched without moving the effecting body is generally adopted.

However, when carrying out the above process, (a)
Processes A and B are not equivalent in terms of reaction difficulty;
The reactivity of Step B, which is an endothermic reaction, is lower than that of Step A, which is an exothermic reaction.

(b) Therefore, when carrying out this process by switching the gas flow paths in a two-unit system, which is the conventional technology, the reaction of the loaded metal acid to the arsenic is completed in step A first, and in step B.
In this case, the reaction is incomplete, resulting in insufficient generation and recovery of hydrogen.

In such a situation, if the gas flow path is switched and both processes are reversed, the amount of reaction between the metal acid [arsenic] and the reducing gas will decrease in the reaction column where hydrogen has not been recovered, and the amount of reaction between the charged The utilization rate of metal acids [arsenic] is low.

(c) In order to avoid the problem in (b), even if the loading amount of metal acid 1 is changed, both steps must be repeated and reversed, making the operation extremely complicated.

There were other problems.

The purpose of the present invention is to eliminate the above-mentioned drawbacks of the prior art, and to change the time ratio of the reaction in which the reduction step A using a reducing gas and the acid step A and hydrogen generation step B using water vapor are carried out for the metal acid arsenic. It is an object of the present invention to provide a method for producing hydrogen that can increase the utilization efficiency of a metal acid and simplify the process flow.

The present invention basically involves installing three or more equivalent reactors loaded with metal acids [arsenic], connecting each reactor through series connecting pipes, bypass pipes, and switching valves. The reactions in both steps are carried out in a number of reactors depending on the reaction time ratio between the two steps.

That is, the present invention provides an equivalent system loaded with a transition metal acid monoarsenic such as molybdenum, tungsten, or vanadium to which a platinum group element is added, and equipped with respective reducing gas and water vapor introduction and discharge piping and switching valves. Using three or more reactors, a step of reducing the metal acid (arsenic) by contacting it with a reducing gas, and bringing water vapor into contact with the reduced metal acid (arsenic) to generate hydrogen. The step is characterized in that the steps are performed alternately by passing the gas through a number of reactors corresponding to the reaction time of each step.

The number of reaction towers in the present invention may be 3 or more,
It is good if the reaction times of two different reactions can be assigned to an equivalent number of reaction columns.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

FIG. 1 is a system diagram showing an embodiment of the present invention in which three reaction columns are arranged.

The reaction towers 1 to 3 loaded with metal acid arsenic are all equivalent, and form a series closed loop through communication pipes 11 to 13, respectively.

The connecting pipes 11 to 13 are provided with dampers 110, 120, and 130, respectively, so that gas can be switched on and off.

Further, one side of each reaction tower is provided with pipes 21 to 23 and pipes 31 to 33 for introducing reducing gas and steam, respectively.
are connected to each other via a switching valve, and waste gas discharge pipes 41 to 43 and hydrogen gas extraction pipes 51 to 53 are respectively connected to the other via a switching valve.

In the above configuration, the reducing gas is guided by the reducing gas introduction pipe 20, and is supplied to each reaction tower via the switching valve 200 and the reducing gas branch pipes 21 to 23 in an on-off manner.

Steam is similarly led through the steam introduction pipe 30, and is passed through the switching valve 300 to each reaction tower through the steam branch pipes 31 to 3.
3, it is supplied on and off.

After the reaction, the reducing gas system waste gas is discharged through the waste gas discharge pipe 41.
~ 43, the waste gas discharge pipe 40 via the switching valve 400
be led to.

This waste gas, like normal combustion exhaust gas, is released into the atmosphere after being subjected to heat recovery, dust removal, etc. as necessary.

Steam-based exhaust gas, that is, hydrogen-containing exhaust gas, is guided to the hydrogen extraction pipe 50 via the hydrogen extraction pipes 51 to 53 and the switching valve 500.

In addition to hydrogen, this gas contains unreacted water vapor and reduction process exhaust gas that remained in the reaction tower. By separating these impurities with a separately installed steam trap, the hydrogen is purified. Ru.

Next, a specific example of operation of the present invention will be explained.

First, reaction tower 1 is used for the reduction process, and reaction towers 2 and 3 are used for the acid production process (hydrogen generation process).

At this time, the dampers installed in the communication pipes 11 to 13 close dampers 110 and 130 and leave damper 120 open.

The reducing gas is led to the reaction tower 1 through the inlet pipe 20, the switching valve 200, and the gas branch pipe 21, and the waste gas after the reaction is discharged from the connecting pipe 11 through the waste gas exhaust pipe 41, the switching valve 400, and the exhaust pipe 40. be done.

On the other hand, the steam is led to the reaction tower 2 through the introduction pipe 30, the switching valve 300, and the branch pipe 32, and reacts with the metal acid [arsenic] in the tower to generate hydrogen.

The water vapor containing hydrogen is then led to the reaction tower 3 through the connecting pipe 12, where a hydrogen generation reaction (acid-1-arsenic reaction) is further advanced, and the generated gas is passed through the connecting pipe 13, the hydrogen extraction pipe 53, and the switching valve 50.
0 and hydrogen extraction pipe 50.

In the reaction tower 1, when the reduction reaction for the charged metal acid [arsenic] is completed, the damper and the switching valve are operated so that the reduction step is carried out in the reaction tower 3, and the acid (burning step) is carried out in the reaction towers 1 and 2. Set each gas flow path.

The next step is to perform a reduction step in reaction tower 2 and an acid step in reaction towers 3 and 1.
The operation is the same as above.

Thereafter, the process returns to the original stage and the reduction step is carried out in reaction tower 1, and the acidic acid step is carried out in reaction towers 2 and 3, and the same operation is repeated.

According to the above example, the reaction time of 1 acid per hour, which has a slow reaction time, is carried out in two reaction towers, and the reduction step, which has a quick reaction time, is carried out in one reaction tower, so the residence time is adjusted according to each reaction. Each reaction can be carried out satisfactorily, and the reaction steps can be switched rationally.

In the above example, three reaction towers were used, and the time ratio for each reaction was operated at 1:2, or depending on the operating conditions such as reaction temperature, 1:3 may be suitable, and in this case, four towers were used. Furthermore, when the time ratio is 2=3, five columns can be provided and each step can be reassigned according to the reaction time.

As described above, according to the present invention, by selecting the number of reaction columns and allocating these numbers according to the time required for both the reduction and acid-1 reactions, the reaction amounts of both reactions can be optimized. Therefore, it is possible to efficiently produce hydrogen while maintaining a high utilization rate of the metal acid arsenate, which is an effector.

Furthermore, by connecting three or more reaction towers in series to form a closed loop, effects such as the ability to quickly switch between both reaction steps and the continuous process can be obtained.

[Brief explanation of drawings]

FIG. 1 is an apparatus system diagram showing an example in which three reaction towers are arranged, which is the basis of the present invention. 1.2.3... Reactor, 11, 12, 13...
...Connection pipe, 20...Reducing gas introduction pipe,
30... Steam introduction pipe, 40... Waste gas discharge pipe, 50... Hydrogen extraction pipe.

Claims (1)

[Claims] 1. Molybdenum, tungsten, added with platinum group elements,
Three or more equivalent reactors each loaded with a transition metal acid such as vanadium and an arsenic compound each equipped with reducing gas and water vapor introduction and exhaust piping and switching valves are used. A step of contacting with a reducing gas to perform a reduction treatment, and a step of contacting the reduced metal acid arsenide with water vapor to generate hydrogen are performed in a number of times corresponding to the reaction time of each step. A method for producing hydrogen, characterized in that the gas is passed through a reactor alternately. 2. The method for producing hydrogen according to claim 1, wherein the platinum group element is at least one element selected from rhodium, platinum, palladium, and ruthenium, or an acid or arsenate thereof. 3. The method for producing hydrogen according to claim 1 or 2, characterized in that the reducing gas is monoacid [arsenic] or carbon [arsenic].