Preparation and characterization of spherical nickel-doped carbonized resin as hydrogenation catalysts: II. Thermal decomposition of resin and preparation of metal-doped catalysts with different nickel loadings

A series of spherical nickel and calcium-doped carbonized resins (Ni–Ca/C), containing Ni metal from 0% to 12% with nearly monodisperse Ni particles distributed from 9 Å to 20 Å and having microporous structure with specific surface area from 510 m2/g to 650 m2/g and high catalytic activity for hydrogenation, were prepared by carbonizing nickel and calcium-doped bead-shaped polymer-D152 Amberlytes (Ni–Ca/D152) having different nickel loadings by exchanging calcium-doped Dl52 resins (Ca/D152) with Ni2+ of different contents in NH3–NH4+ solution as well as C2H5OH solution. The advantage of exchanging Ca/D152 with Ni(NH3)x2+ (x = 1–6) solution is to make bead-shaped Ni–Ca/C with low nickel loadings, and exchanging with Ni2+ (C2H5OH, H2O) solution is preferable to make bead-shaped Ni–Ca/C with high nickel loadings. To increase the understanding of the pyrolysis mechanism of Ni–Ca/D152, GC, DTA, TGA, XRD and elemental analysis were used to investigate the carbonization process and properties of Ni–Ca/C. Nickel and calcium in D152 significantly accelerated the carbonization process and the steam activation process of carbonized resin. The thermal decomposition of D152 mainly occurred between 380 °C and 520 °C. The reduction of nickel ion to metallic nickel and the formation of CaCO3 from Ca(OH)2 and CO2 took place in the carbonization process at 500 °C and below.