Synthesis and Characterization of Ru/Al۲O۳ Nanocatalyst for Ammonia Synthesis

Ru/Al۲O۳ catalysts were prepared by conventional incipient wetness impregnation as well as colloid deposition of RuCl۳ precursor via in situ reduction with ethylene glycol (polyol) method on alumina support. The samples were characterized by TEM, XRD and TPR techniques. The catalytic performance tests were carried out in a fixed-bed micro-reactor under different operating conditions. Ethylene glycol as the reducing agent in the polyol methodproduced well-dispersed and uniform ruthenium nanoparticles with an average diameter of ۷ nm supported on Al۲O۳. In conventional method, however, reduction by hydrogen resulted in considerably larger particles with average size of ۱۲ nm.The Ru/Al۲O۳ catalyst prepared by polyol method exhibited three-fold higher activity in ammonia synthesis compared to the catalyst prepared by conventional method. The turnover frequency ratio of ammonia synthesis of polyol to conventional catalyst was estimated to be ۲.۱ at ۴۵۰°C implying the reaction is structure-sensitive over Ru-based catalysts.

کلیدواژه ها:

Ammonia synthesis ، Ruthenium ، nanoparticles ، Structure-sensitivity ، Alumina support