不同载体Mn-Ce催化剂的制备及其脱硝性能

Preparation of Mn-Ce Catalysts with Various Supports for Analysis of Denitrification

以TiO_2、SiO_2及Al_2O_3为载体,采用分步共混法制备了三种均质整体式Mn-Ce负载型催化剂,探究了不同载体对催化剂脱硝活性、N2选择性及机械强度的影响。结果表明,以TiO_2和SiO_2为载体的催化剂80℃的脱硝率接近90%,而以Al2O3为载体的催化剂仅达46%。催化剂的表征发现这与Mn-Ce/TiO2和Mn-Ce/SiO2催化剂的比表面积和表面酸量较Mn-Ce/Al2O3更大、更多有关。而三种催化剂的N2选择性在80~200℃之间均接近100%,然而Mn-Ce/SiO2催化剂200℃以上N2选择性比其余两种催化剂差。三种催化剂的机械强度为Mn-Ce/TiO2>Mn-Ce/SiO2>Mn-Ce/Al2O3,其微观形貌显示这与催化剂体相结构的密实状况有关,各催化剂的活性组分氧化物均以无定形态存在。

Stepwise blending method was employed to prepare three homogeneous monolithic Mn-Ce supported catalysts with TiO2,SiO2 and Al2O3as the supports.Investigated was the effect of different support on the catalytic activity,N2 selectivity and mechanical strength of the catalysts.The results indicate that denitrification rate of catalysts with SiO2 and TiO2as support approaches to 90% at 80℃,but that of catalyst with Al2O3 as support is just 46%,which is ascribed to larger specific surface area and more acid amount on the interface of Mn-Ce/TiO2 and Mn-Ce/SiO2 catalyst than that of Mn-Ce/Al2O3 catalyst.Approximately 100% N2 selectivity can be obtained at 80-200℃for all the three catalysts.At the temperature above 200℃ however,the N2 selectivity of Mn-Ce/SiO2 is poorer than other two.The mechanical strength of the three catalysts follows that：Mn-Ce/TiO2〉Mn-Ce/SiO2〉Mn-Ce/Al2O3,which is related to the packing degree of the catalyst bulk phase.XRD results illustrate that the active components of the three catalysts all exist in amorphous state.