NO reduction by carbon-based gases based on coal gasification fractions: NO reduction intermediate identification and kinetic analysis

Combining pulverized coal gasifiers with cement kiln production is promising for application in low-cost and efficient NO reduction. This paper presents a pulverized coal gasifier catalytic denitration technique and investigates the homogeneous reduction (by CO and CH 4 ) and heterogeneous catalytic reduction (by coke, CaO, MgO, and Fe 2 O 3 ) of NO. A combination of Chemkin simulations and fixed-bed experiments is used to elucidate the reaction pathways and key intermediates of NO reduction by carbon-based gases. In addition, the activation energies for different catalyst combinations were analyzed via reaction kinetics. The results demonstrate that the presence of small amounts of O 2 inhibits NO reduction by CO but promotes NO reduction by CH 4 . The NCO• radical is essential for the NO reduction process, and the generation of this radical depends on the CH 4 cleavage intermediate and O• radical. CaO and Fe 2 O 3 exhibit more significant catalytic effects on NO reduction by carbon-based gases than the other catalysts tested. The presence of a small amount of O 2 in the reacting gas mixtures facilitates the NO reduction reaction. The activation energy is reduced to 1.02 kJ/mol, and the NO conversion reaches 99.80% when the catalyst is C + CaO + MgO + Fe 2 O 3 and the gas composition is CO + CH 4 + O 2 . This work provides theoretical support and data recommendations for the use of pulverized coal gasifiers for the denitrification of cement kilns.