A Ni/Mg–Al catalyst with an atomic ratio of Ni:Mg:Al = 0.5:2.5:1
was prepared by a co-precipitation method [35]. First, two aqueous
solutions, one being the mixture of Ni(NO3)2 (0.125 mol/L),
Mg(NO3)2 (0.625 mol/L) and Al(NO3)3 (0.25 mol/L), and the other
being the mixture of Na2CO3 (0.125 mol/L) and NaOH (2 mol/L),
were added slowly into a four-neck flask under strong stirring,
and meanwhile the pH value of the solution in the flask was adjusted
to 10 by carefully controlling the addition speed of the
two solutions. Second, the product solution including the light
green precipitate formed was aged at 60 C for 12 h, and then the
precipitate was filtered followed by washing repeatedly with distillated
water until the filtrate was neutral. Finally, the precipitate
was dried at ambient temperature for 24 h and at 110 C for 24 h,
followed by calcined in air at 850 C for 5 h (at a heating rate of
5 C/min). For simplicity, the as-prepared catalyst was denoted
by Ni0.50/Mg2.50Al. Our recent investigations have demonstrated
that Ni0.50/Mg2.50Al has excellent activity and stability for the
SMR reaction due to its high specific surface area and high Ni dispersion.
In a 200 h test for the Ni0.50/Mg2.50Al catalyst