Study On Selective Catalytic Reduction Of NO_x By CH₄ With Modified In/H-Beta

NOx in flue gas is an important kind of atmospheric pollutant.N itrogen oxides have a lot of adverse effects on human health and production.In/H-Beta has good CH4-SC R denitration performance without SO2 and H2 O.However,There is a problem of poor SO2 resistance and H2 O resistance.This paper mainly studies the performance modification of In/H-Beta catalyst.A series of studies on the modification,preparation conditions optimization and influence of reaction conditions of In/H-Beta catalysts were carried out.It is found that In/H-Beta has poor SO2 and H2 O resistance.Under the condit ion of 100 ppm SO2 and 5% H2 O,the highest denitration rate of the catalyst is only 32.8%.Second methods of metal loading and metal oxide doping were used to modify In/H-Beta in two ways.In the modified catalyst,Co-In/H-Beta,In-Cr2O3/H-Beta,In-Mn O2/H-Beta,In-Fe2O3/H-Beta,In-C o3O4/H-Beta and In-N i O /H-Beta have better SO2 and H2 O resistance than In/H-Beta.The In-Co3O4/H-Beta catalyst has the best C H4-SCR denitration performa nce in the presence of SO2 and H2 O.The highest denitrification rate could reach 83.1%.The influence of different preparation condit ions on In-C o3O4/H-Beta catalyst was studied.The results show that the structure of molecular sieve can be more consolidated by ion-exchange method with C o3O4 than by impregnation.Si/Al ratio of H-Beta which is 25 have more Br?nsted acid sites.The catalyst prepared with this kind of zeolite has better denitration performance.When Co3O4/H-Beta is 1:8,the catalyst has the best modification effect.The optimum concentration of In in ion exchange solution was 0.033 M.At this point,the In load tends to saturation.The optimum calcination temperature of the catalyst is 500 ℃.At this point,In O+/In2O3 was 1.06.In the presence of SO2 and H2 O,the denitrification rate of the optimized In-Co3O4/H-Beta can reach 87.6% at 625 ℃.The C H4-SC R denitration performance of In-Co3O4/H-Beta catalyst under different reaction conditions was also studied.The results show that the change of SO2 concentration and H2 O concentration has a great influence on the catalyst.When the SO2 concentration is between 0-100 ppm and the H2 O concentration is between 0-8%,the catalyst has good resistance to SO2 and H2 O resistance.The catalyt ic effect of the catalyst increases with the increase of C H4/NO ratio.When the oxygen concentration is 8%,the catalyst has the best denitration effect.In-Co3O4/H-Beta catalyst has better catalytic removal effect for NO below 600 ppm.The catalytic effect increases with the decrease of space velocity.The highest denitration rate was 97.6% when the air velocity was 9 440 h-1,CH4 /NO=1,the oxygen concentration is 10%,the NO concentration is 400 ppm,the SO2 concentration is 100 ppm and the H2 O concentration is 5%.The results show that In-Co3O4/H-Beta catalyst has great SO2 and H2 O resistance.