ScholarWorks@중앙대학교

초록

Three different precursors were used to synthesize isolated Ni sites as well as to stabilize them on an Al2O3 support for the dry reforming of methane (DRM) reaction. The precursors used are bis(cyclopentadienyl)nickel(II) (A cycle), trimethyl aluminum (B cycle), and water (C cycle). This so-called ABC-type atomic layer deposition (ALD) was performed for 15 cycles, and then overcoated with an Al2O3 layer via ALD to enhance the stability of the DRM catalyst. Pore morphologies were retained after this ABC-type ALD/calcination/additional Al2O3 ALD, confirming the thin film deposition occurs without compromising pore structure of the Al2O3 support. Calcination after 15 cycles of ABC-type ALD is required to recover the DRM activity as well as to improve the stability. Overcoating with 5 cycles of Al2O3 results in higher peak DRM activity versus the calcined catalyst, but that with 10 cycles does not. Additional Al2O3 overcoating changes the deactivation rate constants to a small extent, but results in induction periods indicating the presence of NiAl2O4. The catalyst with 5 cycles of Al2O3 overcoating shows a higher peak DRM rate than those with 0 and 10 cycles, and a lower deactivation rate constant. These results indicate that achieving an optimum number of ABC cycles may help resolve the trade-off between peak rate and deactivation behavior for Ni DRM catalysts.

키워드