fig9

Figure 9. Carbon phase formation and residual inorganic content of xNi-LCCM-derived carbon products. (A) XRD patterns of spent LCCM and xNi-LCCM catalysts after methane decomposition at 750 °C for 8 h. Diffraction peaks corresponding to LCCM, metallic Ni, and graphitic carbon are marked; (B and C) TGA and derivative weight curves of acid-treated carbon products obtained from (B) 050Ni-LCCM and (C) 150Ni-LCCM after treatment with 5 M HNO₃. The residual masses after carbon oxidation were used to estimate the remaining inorganic contents. XRD: X-ray diffraction; TGA: thermogravimetric analysis; LCCM: (La_0.75Ca_0.25)(Cr_0.5Mn_0.5)O_3-δ.