Calcium Poisoning Mechanism of Cu‐SAPO‐18 for Selective Catalytic Reduction of NO_x with Ammonia

Abstract

To investigate the effect of Ca poisoning on Cu-SAPO-18, a series of samples with different Ca amounts were prepared by the impregnation method, and their NH 3-SCR activities were evaluated. When the Ca amount was 0.8 mmol/g cat , NO conversion at 350°C was 40.6% (lower than that over the fresh Cu-SAPO-18 sample), which shows that the catalytic deNO x performance was significantly decreased after Ca poisoning. Ca poisoning did not have a great influence on the structure of Cu-SAPO-18, but the formed CaO blocked part of the micropores, which reduced surface area and micropore volume, and further reduced accessibility of the active sites and surface acidity of the sample. The total amount of the isolated Cu 2 + species decreased from 62.83 μmol/g Cu-SAPO-18 to 23.45 μmol/ g 0.8Ca-Cu-SAPO-18 , which resulted in conversion of the isolated Cu 2 + species to Cu 2 O in the sample after the addition of Ca. In addition, the substitution of Ca 2 + with H or Cu 2 + in Si-O(H)-Al or Si-O(Cu 2 +)-Al to form the Si-O(Ca 2 +)-Al species decreased amounts of the Lewis and Brönsted acid sites, which might be the important reasons for the drop in catalytic activity. Both the Eley-Rideal (E-R) and Langmuir-Hinshelwood (L-H) reaction mechanisms existed over the samples in the NH 3-SCR reaction, but the L-H reaction mechanism was dominant. The catalytic mechanism over the sample did not change, but the reaction was slower after Ca poisoning.

Wideband Channel Estimation for THz Massive MIMO

“…Proof: According to the analysis in [30], the element index n max l,m of the angle-domain representation q l,m with the largest power is N as a physical channel direction different from ψ l = θn , where b is a non-zero integer. Based on (10), for the M -th subcarrier, we can obtain…”

Enhanced catalytic activity of Fe–Ce catalysts determined by synergistic effect of different precursors in selective catalytic reduction of NOx with NH3

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Catalytic Decomposition of H2O2 for NO Oxidation‐Removal over Hierarchical Fe‐ZSM‐5: Effect of Ethanol on Zeolite Performance

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