Effective adsorbents for sulphur dioxide (SO₂) removal were investigated in this work. The conventional adsorbent for gas purification is normally operated at low temperature (below 200ºC), which is not suitable for the removal of SO₂ in hot flue gas. Pillared clays and calcined layered double hydroxides (LDHs), which have been widely studied for many catalytic applications at high temperature, are of a great potential for SO₂ removal from hot flue gas. In the current study, SO₂ adsorption performances of pillared clays and calcined LDHs were evaluated. _{2 2}...[ Read more ]

Effective adsorbents for sulphur dioxide (SO₂) removal were investigated in this work. The conventional adsorbent for gas purification is normally operated at low temperature (below 200ºC), which is not suitable for the removal of SO₂ in hot flue gas. Pillared clays and calcined layered double hydroxides (LDHs), which have been widely studied for many catalytic applications at high temperature, are of a great potential for SO₂ removal from hot flue gas. In the current study, SO₂ adsorption performances of pillared clays and calcined LDHs were evaluated.

Different metal species have been used to prepare pillared clays with bentonite as the supporting material. Ce and Zr pillared clays are found to have better SO₂ adsorption performance than other pillared clays. The SO₂ adsorption performance of pillared clay with different Ce and Zr content are also investigated. Several calcined LDHs with different Ce and Zr content are synthesized with Mg and Al as the major component. SO₂ adsorption performance of calcined LDHs with carbonate exchange and synthesized at higher pH are also investigated. It is found that Ce and Zr are active species for SO₂ adsorption, which have strong attractions to SO₂. Also calcined LDHs are found to have outstanding performance for SO₂ removal. The adsorption capacities of calcined LDHs are in average 100% higher than pillared clays and 300% higher than activated carbon and ZSM-5 at 200°C.

The current results have demonstrated that calcined LDHs can achieve high SO₂ adsorption capacities at high temperature. As the synthesis procedure of calcined LDHs is not complicated, with further development, calcined LDHs can be developed into effective adsorbents for industrial SO₂ removal.