Abstract: A cleaning process of harmful gas containing at least one kind selected from trimethylgallium, triethylgallium, trimethylindium, triethylindium, trimethylaluminum and triethylaluminum as a harmful component by bringing into contact with a cleaning agent comprising a metallic oxide essentially containing copper (II) oxide and manganese (IV) oxide; and an alkali metal compound, thereby removing the harmful component from the harmful gas. According to the invention, a cleaning process of harmful gas containing harmful component such as trimethylgallium exhausted from manufacturing process of gallium nitride-based compound semiconductor, which efficiently cleans with superior cleaning capacity without reducing the removing efficiency of harmful component and without generating new harmful component of nitrogen oxides, etc., even in the case where the harmful gas to be treated is dry, or even in the case where the harmful gas contains ammonia is realized.

Abstract: There are disclosed a process for purifying ammonia which comprises bringing crude ammonia into contact with a catalyst comprising manganese oxide as an effective ingredient to remove oxygen and/or carbon dioxide that are contained as impurities in the ammonia, and a process for purifying ammonia which comprises bringing crude ammonia into contact with a catalyst comprising manganese oxide as an effective ingredient, and thereafter with a synthetic zeolite having a pore diameter in the range of 4 to 10 Å to remove at least one impurity selected from the group consisting of oxygen, carbon dioxide and moisture that are contained in the crude ammonia. It is made possible by the above process to remove impurities to an extremely low concentration from crude ammonia available on the market for industrial use and crude ammonia from a gallium nitride compound semi-conductor without decomposition of ammonia to generate hydrogen.

Abstract: A process for purifying ammonia removing impurities contained in a crude ammonia which comprises contacting a crude ammonia with a purification agent comprises: a manganese oxide (1), and at least one kind of metal oxide (2) selected from vanadium oxide, chromium oxide, stannic oxide, zirconium oxide, bismuth oxide, niobium oxide and tantalum oxide as an effective component; wherein a ratio between a number of manganese atom and a number of the entire metallic atoms of the effective component is 80 to 99%; and preferably further contacting with a synthetic zeolite. The purification agent enables to remove a slight amount of impurities such as oxygen, carbon dioxide and moisture to an extremely low concentration, and any repeated reproduction of the purification agent does not reduce the capability of removing impurities in crude ammonia, and the longevity of the purification agent was remarkably elongated than the conventional purification process.

Abstract: There are disclosed a process for purifying ammonia which comprises bringing crude ammonia into contact with a catalyst comprising manganese oxide as an effective ingredient to remove oxygen and/or carbon dioxide that are contained as impurities in the ammonia, and a process for purifying ammonia which comprises bringing crude ammonia into contact with a catalyst comprising manganese oxide as an effective ingredient, and thereafter with a synthetic zeolite having a pore diameter in the range of 4 to 10 Å to remove at least one impurity selected from the group consisting of oxygen, carbon dioxide and moisture that are contained in the crude ammonia. It is made possible by the above process to remove impurities to an extremely low concentration from crude ammonia available on the market for industrial use and crude ammonia from a gallium nitride compound semi- conductor without decomposition of ammonia to generate hydrogen.