Catalyst for producing hydrogen and method for producing hydrogen

Abstract

A metal-supporting catalyst for decomposing ammonia into hydrogen and nitrogen. The catalyst shows a high performance with a low cost and being advantageous from the viewpoint of resources, and an efficient method for producing hydrogen using the catalyst. The catalyst catalytically decomposes ammonia gas to generate hydrogen. The hydrogen generation catalyst includes, as a support, a mayenite type compound having oxygen ions enclosed therein or a mayenite type compound having 1015 cm−3 or more of conduction electrons or hydrogen anions enclosed therein, and metal grains for decomposing ammonia are supported on the surface of the support. Hydrogen is produced by continuously supplying 0.1-100 vol % of ammonia gas to a catalyst layer that comprises the aforesaid catalyst, and reacting the same at a reaction pressure of 0.01-1.0 MPa, at a reaction temperature of 300-800° C. and at a weight hourly space velocity (WHSV) of 500 / mlg−1h−1 or higher.

Description

TECHNICAL FIELD[0001]The present invention relates to a catalyst for producing hydrogen and a method for producing hydrogen from ammonia using the catalyst.BACKGROUND ART[0002]When ammonia contained in various exhaust gases is discharged in the environment, it is necessary to detoxifying ammonia because ammonia has an odor, and for example, a method of oxidatively decomposing ammonia by contact with oxygen, and a method of directly decomposing ammonia to hydrogen, and the like have been proposed. Ammonia decomposition reaction is industrially used for producing atmospheric gas composed of nitrogen and hydrogen used for bright annealing of stainless steel, nickel steel, and the like.[0003]Also, use of hydrogen as a clean energy source has recently attracted attention from the viewpoint of environmental protection and, for example, a method of recovering hydrogen from ammonia produced from organic waste and fuel cell vehicles using hydrogen as fuel have been actively developed. Hydrog...

AI Technical Summary

Benefits of technology

[0057]An ammonia decomposition method using the hydrogen-producing catalyst of the present invention permits ammonia contact decomposition even under mild conditions of 350° C. and 0.1 MPa and at a high weight hourly space velocity (WHSV) using, as a base material, a mayenite-type compound which is composed of only elements with a high Clarke number, such as calcium, aluminum, and oxygen, and which is an easily synthesizable, low-cost, and nontoxic compound. Also, the method can produce high-purity hydrogen by decomposition with a high conversion rate using a transition metal element, for example, Co, Ni, or the like, other than expensive rare metals such as Ru, and is advantageous from the viewpoint of effective utilization of resources. In addition, unlike a usual alumina-supported catalyst, an alkali metal or alkaline-earth metal compound or the like need not be added as an accelerator for improving the conversion rate, thereby simplifying a process for producing a supported metal catalyst.

Problems solved by technology

Hydrogen is preferred as clean energy, but particularly when hydrogen is used as a raw material of fuel cells for automobile cars, a method of supplying hydrogen to fuel cells has been a problem because of the necessity for a large volume of storage.

However, in the catalyst of this method, Ni easily reacts with alumina to produce a NiO—Al2O3 solid solution, thereby failing to produce a mayenite-type structure.

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