Waste pulp chemical-looping gasification using Ni-modified electroplating sludge as an oxygen carrier

Waste pulp (WP) is a typical byproduct of paper industry, and Chemical-looping gasification (CLG) as a recently developed technology is highly suited to dispose high-volatile wastes like WP. In order to make a high-efficiency oxygen carrier (OC) for CLG of WP, the Ni-containing electroplating sludge (NES) was used as the matrix and NiO modification was performed to enhance the hydrogen production in CLG. These resulted in a potentially high-efficiency OC denoted as NNES. Testing CLG of WP was in a fixed-bed reactor at 850 °C by adopting NNES as the OC, injecting 2.4 mL/g(WP) water, and keeping a mass ratio of 1.0 between OC to WP. It produced 1.73 Nm³/kg syngas that has an LHV of 11.9 MJ/Nm³ and a H₂/CO ratio of 3.63. In 10 redox cycles, the syngas yield did not have obvious decrease, but a certain reduction in the activity of NNES was observed. Characterization of the spent NNES revealed that it is the Ni agglomeration and inert silicate generation which reduced the activity of NNES.