Table 1. Size of Ni Crystals of the Reduced Catalysts and Spent Catalysts.

	Ni-cluster (d/nm)
catalyst	after reduction	after reaction	increasing rate (%)
Ni-Ca-0	26.53	45.36	41.51
Ni-Ca-1	16.54	30.82	46.33
Ni-Ca-2	13.76	23.16	40.57
Ni-Ca-4	13.67	25.17	45.68
Ni-Ca-6	16.77	24.51	31.59