The pyrolysis behavior of Ni–Ca/D152 was determined by thermogravi- metric analysis (TGA) and differential thermal analysis (DTA) using a Gen- eral V 2.2A Dupont 9900 analyzer. The heating rate was set at 5 C/min. The weight loss and thermal change were recorded in the range of 25–800 C. The tail gas of pyrolysis from 100 C to 500 C was determined by a gas chro- matograph (GC) (SP-2305) equipped with a thermal conductivity detector and a capillary column (stationary phase GD • 502, length 3 m).
The nickel contents of Ni–Ca/C and Ni–Ca/D152 were measured by a flame atomic absorption spectrometry at the resonance wavelength using a HITACHI 180-80 apparatus. Elemental analysis of carbon, hydrogen and nitrogen in the carbonized resin was carried out using an Elementar Vario EL elemental analyzer. X-ray analysis was made by a RIGAKU2308 apparatus with a CuKa radiation resource. Hydrogen temperature-pro- grammed reduction (TPR) study was performed from room temperature to 500 C in a conventional apparatus equipped with a thermal conductiv- ity detector (TCD). Oxygen temperature-programmed oxidation (TPO) was run in the same instrument as TPR. The TPO operation is just reverse
to that of TPR. Nickel dispersion (RNi, in %) and particle size (d Ni , in A˚ )
were determined by H2–O2 titration using pulse method. Nitrogen adsorp-
tion/desorption isotherms at liquid nitrogen temperature (77 K) were mea-
sured using a ST-03 instrument. The experimental details were described in
our previous paper [6].