Metal impregnation on steel converter slag as an oxygen carrier

Journal article, 2023

Oxygen carriers used in chemical looping processes operated with biofuel are affected by
the inorganic matter of the fuel. It is therefore expected that the lifetime of the oxygen carrier is limited,
and preferably low-cost oxygen carriers should be used. Oxygen carriers based on iron ore or steel
manufacturing waste products are available in significant quantities at low cost. However, it is common
for these types of materials that their reactivity is low. This study investigates the effect of adding small
amounts of more reactive elements into steel converter slag, also called LD slag. Slag particles were
wet impregnated with 2 or 5 wt.% of Ni, Cu, Mn, or Ce. The new material’s morphology was evaluated
using X-Ray Diffraction and SEM-EDS. Changes in reactivity towards CO, CH4 and the model tar
molecule benzene were evaluated using a bench-scale laboratory fluidized bed reactor. It was
observed that even small amounts of either Ni, Cu, or Mn could increase reactivity toward CO. Both Cu
and Mn formed phases with LD slag that released oxygen via CLOU (chemical looping with oxygen
uncoupling) and increased the conversion of methane and benzene. Ni and Ce doping also increased
methane conversion but had only a minor effect on the benzene conversion.