Mn-La-Ce-Ni-O_x低温脱硝的影响因素

Influence factors on low-temperature de NO_x performance of Mn-La-Ce-Ni-O_x

采用共混法制备系列Mn-La-Ce-Ni-Ox复合氧化物脱硝催化剂,考察了金属元素配比、反应温度、空速、n（NH3）/n（NO）、水蒸气和SO2对催化剂低温NH3选择性催化还原法（SCR）脱除NO的影响。运用X线衍射仪（XRD）、N2吸附分析仪、傅里叶变换红外光谱仪（FT-IR）等表征,分别对催化剂的固相结构、比表面积、孔径分布和官能团结构进行分析。结果表明：当n（Mn）∶n（La）∶n（Ce）∶n（Ni）为2.5∶2.5∶1∶1时,催化剂在活性温度110～300℃内NH3-SCR脱除NO效率最高;5 000 h^-1以下空速对脱硝活性无影响;脱硝活性随NH3与NO摩尔比的增大而增大（n（NH3）/n（NO）≤1.0时）,NH3过量无影响;140℃时,同时通入水蒸气和SO2后,催化剂脱除NO效率仍保持在80%以上。Mn2.5-La2.5-Ce-Ni-Ox催化剂比表面积大,具有中等孔不受限制的单分子层和多分子层的吸附特征。

A series of Mn-La-Ce-Ni-Oxcomplex oxides were prepared by a chemical blend method for selective catalytic reduction（ SCR） of NO at low-temperature. Effects of molar ratio on metal elements,reaction temperature,space velocity,n（ NH3） /n（ NO）,H2 O and SO2 on catalytic performance of the MnLa-Ce-Ni-Oxfor NH3-SCR of NOxwere studied. The solid-phase structure,specific surface area,distributions of pore diameter and volume, and functional group structure of the catalysts were characterized by X-ray diffraction（ XRD）,N2 adsorption and Fourier transform infrared spectroscopy（ FT-IR）. Results showed that the Mn-La-Ce-Ni-Ox（ n（ Mn） ∶ n（ La） ∶ n（ Ce） ∶ n（ Ni） = 2. 5∶ 2. 5∶ 1∶ 1 in mol） had the best NO removal efficiency at temperature range of 110 ℃-300 ℃. The NO removal efficiency was not effected by space velocity when it was less than 5 000 h^-1; The NO removal efficiency increased with the increasing of n（ NH3） /n（ NO） as n（ NH3） /n（ NO） ≤ 1. 0 and unchanged as n（ NH3） /n（ NO）〉 1. 0. The NO removal efficiency was still above 80% by injecting SO2 and H2O at 140℃. Mn2. 5-La2. 5-Ce-Ni-Oxhad a large specific surface area and middle pore had no limitation in monolayer and multimolecular layer adsorption.