Nickel catalysts for nitrogen–hydrogen mixture purification from carbon oxides

Abstract

Objectives. This study is devoted to developing new-generation nickel (Ni) catalysts for the purification of a nitrogen–hydrogen mixture from carbon oxides, which should encompass the best qualities of the NIAP-07-series solid catalysts. Methods. This study used derivatographic and radiographic methods; temperature-programmed recovery, decomposition, and joint temperature-programmed decomposition and recovery; and low-temperature nitrogen adsorption (specific surface determination). The mechanical strength of catalysts was determined using an MP-2C device by crushing granules with an applied load on the end face. The chemical composition and catalytic activity were determined by the methods of TU 2178-003-00209510 Technical Conditions. Results. Many studies regarding Ni–aluminum (Al)–calcium (Ca) methanation catalyst at all stages of its preparation have been conducted. It is demonstrated that Ni hydrocarboxyaluminate, a precursor of the active component of the catalyst, is formed when Ni hydroxocarbonate is mixed with active alumina in the presence of an aqueous solution of ammonia, and its chemical formula is established. Moreover, it was found that the mechanical strength of the catalyst is determined by the amount of industrial Ca aluminate added to the Ni–Al composition. The compositions of catalysts with different contents of the active component have been optimized. Conclusions. The developed catalyst has a low activation temperature and high catalytic activity, thermal stability, and mechanical strength and is resistant to organic and alkaline carbon dioxide absorbers. The catalyst can be produced in the form of a ring, cylindrical tablets, and extrudates of various geometric sizes. The methanation unit at Stavrolen (Budennovsk, Stavropol krai, Russia) has begun commercially operating the catalyst.