Study On Anti-poisoning Performance And Preparation Of Mn-Ni Composite Oxides Catalyst Containing Tourmaline

At present,commercial VWTi catalysts are not applicable for flue gas denitrification in cement kiln due to their high optimum working temperature（300-400°C）.Therefore,it is significance that develop a catalyst having excellent low-temperature activity and high SO₂-tolerance.A series of multi-shell hollow structure Mn-Ni-oxide and tourmaline/Mn-Ni-oxide composite catalytic material were prepared by hard template method,and used x-ray diffraction（XRD）and transmission electron microscopy（TEM）,x-ray photoelectron spectroscopy（XPS）,hydrogen temperature programmed reduction（H₂-TPR）and denitrification activity tests to characterize the crystal structure,microstructure,surface element content and reduction properties of the composite,and Infrared（in situ DRIFTS）method further studied the denitrification mechanism and SO₂-tolerance mechanism of composite catalytic materials.The effects of manganese-nickel ratio,precipitant addition amount and reaction temperature on the properties of manganese-nickel oxide composite catalytic materials were investigated.When the molar ratio of manganese to nickel is 4:1,the molar ratio of precipitant to metal total ion is 4:1,and the reaction temperature is 80°C,the composite catalytic material has the best performance.It presented 89%NO_xconversion at 110°C and100%NO_xconversion from 125 to 240°C.The denitrification activity of the composite catalytic material can still be maintained above 70%in the presence of 200ppm SO₂and 10 vol.%H₂O at 150°C.In order to improve the low temperature activity and anti-poisoning performance of manganese-nickel oxide composite catalytic materials.The effect of the addition of tourmaline on the properties of composite catalytic materials was investigated.When the addition amount of tourmaline is 2%,the composite catalytic material presented 65%NO_xconversion at 80°C,92%at 110°C and 100%NO_xconversion from 125 to 240°C.The composite catalytic material showed 80%NO_xconversion in the presence of 200 ppm SO₂and 10 vol.%H₂O at 150°C.It is found that the addition of tourmaline can control the growth of the precursor deposited on the surface of the carbon sphere,promote its nucleation,and refine the grain to make the tourmaline/manganese-nickel oxide composite.The thickness of the catalytic material shell is thinned,which facilitates the diffusion and transfer of the reaction gas.At the same time,the addition of tourmaline can promote the conversion of some active components to amorphous form,improve the relative content of Mn⁴⁺and chemisorbed oxygen（Oα）on the surface of composite catalytic materials,enhance their adsorption and activation ability to NO and NH₃,and accelerate the SCR reaction.The composite catalytic materials all follow the L-H and E-R mechanisms,and the addition of tourmaline can enhance the adsorption capacity of the composite catalytic materials for NO and NH₃.In the sulfur-containing atmosphere,the nitrate-active species adsorbed on the surface of the tourmaline/manganese-nickel oxide composite catalytic material can still exist stably.And SO₂has little effect on the adsorption of NH₃on the surface of tourmaline/manganese nickel oxide composite catalytic material.Therefore,the tourmaline/manganese nickel oxide composite catalytic material has excellent resistance to SO₂.