کد مقاله کد نشریه سال انتشار مقاله انگلیسی نسخه تمام متن
210145 461698 2013 6 صفحه PDF دانلود رایگان
عنوان انگلیسی مقاله ISI
Structure sensitivity of ammonia decomposition over Ni catalysts: A computational and experimental study
موضوعات مرتبط
مهندسی و علوم پایه مهندسی شیمی مهندسی شیمی (عمومی)
پیش نمایش صفحه اول مقاله
Structure sensitivity of ammonia decomposition over Ni catalysts: A computational and experimental study
چکیده انگلیسی

Ni catalysts are widely used to catalyze ammonia decomposition. In this study, first-principles calculations are performed to investigate the preferred adsorption sites and the adsorption energies of NHx (x = 0–3) and H, and the transition states, activation energies and rate constants of NH3 stepwise dehydrogenation and associative desorption of N on the stepped Ni(211) and the close-packed Ni(111) surfaces. The results show that the barrier of associative desorption of N, which is higher than those of NH3 stepwise dehydrogenation, on Ni(211) are 1.10 eV higher than that on Ni(111), indicating that the associative desorption of N on Ni(211) is difficult to take place. Hence the strongly adsorbed N atoms would block some of the step sites of Ni(211). The N-blocking Ni(211) surface is constructed, and then NH3 decomposition on 2N–Ni(211) is investigated. The results indicate that Ni catalysts with too many or too few step sites, which can be associated with Ni particle sizes, show low ammonia decomposition activities. Therefore, different sized Ni-based catalysts are employed to catalyze ammonia decomposition, and TOFH2 as a function of Ni particle size is correlated. Finally, the structure sensitivity of ammonia decomposition over Ni catalysts is rationally interpreted.

Figure optionsDownload as PowerPoint slideHighlights
► NH3 decomposition on Ni(111) is more active than that on Ni(211).
► Strongly adsorbed N atoms are easy to block some of Ni step sites.
► The optimum Ni particle size is around 3.1–3.6 nm for NH3 decomposition.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Fuel Processing Technology - Volume 108, April 2013, Pages 112–117
نویسندگان
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