用溶胶凝胶法合成了3种不同B位的钙钛矿催化剂,同时用X射线衍射(XRD)、比表面积分析(BET)、扫描电镜(SEM)、程序升温化学吸附(TPR)4种手段对催化剂进行了物理化学表征。从经济性和实际性考虑,本研究使用了清洁无二次污染的H2作为SCR的...用溶胶凝胶法合成了3种不同B位的钙钛矿催化剂,同时用X射线衍射(XRD)、比表面积分析(BET)、扫描电镜(SEM)、程序升温化学吸附(TPR)4种手段对催化剂进行了物理化学表征。从经济性和实际性考虑,本研究使用了清洁无二次污染的H2作为SCR的还原剂,同时控制了H2的加入比例,在小NO/H2比(1∶1、1∶5、1∶10)情况下,考察了3种催化剂的催化效率。由于实际燃煤烟气中含有大量的O2,因此,同时考察了高O2(O2/NO=100∶1)的加入对氧化还原反应的影响。从考察结果我们得知,在NO/H2为1∶1时,La Co O3和La Ni O3的催化活性优于La Mn O3,达到80%。而在高H2/NO比时,则是La Mn O3的催化活性最高,达95%以上。O2的加入对氧化还原反应影响较大,温度高于250℃时,O2出现竞争性反应,消耗了大部分的还原剂,使得NO脱除率降低,而在250℃以下,O2的影响较小。展开更多
Selective catalytic reduction of NOχ by H2 in the presence of oxygen has been investigated over Pt/ A12O3 catalysts pre-treated under different conditions. Catalyst preparation conditions exert significant influence ...Selective catalytic reduction of NOχ by H2 in the presence of oxygen has been investigated over Pt/ A12O3 catalysts pre-treated under different conditions. Catalyst preparation conditions exert significant influence on the catalytic performance, and the catalyst pre-treated by HE or H2 then followed by O2 is much more active than that pre-treated by air. The higher surface area and the presence of metallic Pt over Pt/A12O3 pre-treated by HE or pretreated by H2 then followed by O2 can contribute to the formation of NO2, which then promotes the reaction to proceed at low temperatures.展开更多
Pd/TiO2 catalysts prepared by three different methods(impregnation,deposition-precipitation,and polyethylene glycol reduction)were investigated in the selective catalytic reduction of NOx by H2(H2-SCR).It was found th...Pd/TiO2 catalysts prepared by three different methods(impregnation,deposition-precipitation,and polyethylene glycol reduction)were investigated in the selective catalytic reduction of NOx by H2(H2-SCR).It was found that the preparation method exerted a significant effect on the activity of the Pd/TiO2 catalyst,and that the catalyst prepared by the polyethylene glycol reduction method exhibited the highest activity in the reduction of NOx.Characterization of the catalyst showed that,in the Pd/TiO2 catalyst prepared by the polyethylene glycol reduction method,the existing Pd species was Pd0,which is the desirable species for the H2-SCR of NOx.In situ DRIFTS studies demonstrated that over this catalyst,more chelating nitrite and monodentate nitrite species formed,both of which are reactive intermediates in the H2-SCR of NOx.All of these factors account for the high activity of Pd/TiO2 prepared by the polyethylene glycol reduction method.展开更多
In this study, the promotion effect of H2 pretreatment on the SCR performance of CeO2 catalyst was investigated based on the characterization results of XRD, H2-TPR, Raman and in situ DRIFT techniques.Lower crystallin...In this study, the promotion effect of H2 pretreatment on the SCR performance of CeO2 catalyst was investigated based on the characterization results of XRD, H2-TPR, Raman and in situ DRIFT techniques.Lower crystallinity, higher reducibility and surface acidity can be found on CeO2-H catalyst. The results of DRIFT study reveal that the pretreatment of CeO2 catalyst with H2 can facilitate the adsorption of NH3 and NOx species, while the adsorbed NOx is basically inactive in the NH3-SCR reaction. Moreover, the reaction mechanism of the NH3-SCR reaction over CeO2 catalyst is not changed by H2 pretreatment,which is mainly under the control of Eley-Rideal（E-R） mechanism, The enhanced SCR performance of CeO2-H catalyst is mainly due to the promoted NH3 adsorption and the subsequent facilitation of SCR reaction through E-R pathway.展开更多
A series of Ni,Sn and Ca modified Pd/TiO2-Al2O3catalysts were prepared by the incipient wetness impregnation method and their catalytic performance for the selective catalytic reduction of NOxby H2was evaluated.The re...A series of Ni,Sn and Ca modified Pd/TiO2-Al2O3catalysts were prepared by the incipient wetness impregnation method and their catalytic performance for the selective catalytic reduction of NOxby H2was evaluated.The results showed that the NOxconversion and N2selectivity were improved over Pd-Sn/TiO2-Al2O3and Pd-Ni/TiO2-Al2O3catalysts above 200°C.More importantly,the N2selectivity and high-temperature activity of Pd-Sn/TiO2-Al2O3catalyst was far superior to the single Pd/TiO2-Al2O3catalyst.The optimal Sn loading was 2 wt.%.X-ray diffraction(XRD)results showed that the interaction between Pd and Sn promotes the dispersion of Pd over TiO2-Al2O3.Temperature-programmed reduction(H2-TPR)results demonstrated that the addition of Sn contributes to the formation of Pd0and improving the redox property of Pd/TiO2-Al2O3.The additives of Ni and Sn also facilitated the absorption of NOxand the oxidation of NO to NO2,which play important roles in the selective catalytic reduction of NOxby hydrogen.展开更多
文摘用溶胶凝胶法合成了3种不同B位的钙钛矿催化剂,同时用X射线衍射(XRD)、比表面积分析(BET)、扫描电镜(SEM)、程序升温化学吸附(TPR)4种手段对催化剂进行了物理化学表征。从经济性和实际性考虑,本研究使用了清洁无二次污染的H2作为SCR的还原剂,同时控制了H2的加入比例,在小NO/H2比(1∶1、1∶5、1∶10)情况下,考察了3种催化剂的催化效率。由于实际燃煤烟气中含有大量的O2,因此,同时考察了高O2(O2/NO=100∶1)的加入对氧化还原反应的影响。从考察结果我们得知,在NO/H2为1∶1时,La Co O3和La Ni O3的催化活性优于La Mn O3,达到80%。而在高H2/NO比时,则是La Mn O3的催化活性最高,达95%以上。O2的加入对氧化还原反应影响较大,温度高于250℃时,O2出现竞争性反应,消耗了大部分的还原剂,使得NO脱除率降低,而在250℃以下,O2的影响较小。
文摘Selective catalytic reduction of NOχ by H2 in the presence of oxygen has been investigated over Pt/ A12O3 catalysts pre-treated under different conditions. Catalyst preparation conditions exert significant influence on the catalytic performance, and the catalyst pre-treated by HE or H2 then followed by O2 is much more active than that pre-treated by air. The higher surface area and the presence of metallic Pt over Pt/A12O3 pre-treated by HE or pretreated by H2 then followed by O2 can contribute to the formation of NO2, which then promotes the reaction to proceed at low temperatures.
基金supported by the National Key R&D Program of China(2017YFC0210700)the National Natural Science Foundation of China(21876009,21611130170)+1 种基金the Beijing Municipal Natural Science Foundation(8162030)the Fundamental Research Funds for the Central Universities(XK1802-1)~~
文摘Pd/TiO2 catalysts prepared by three different methods(impregnation,deposition-precipitation,and polyethylene glycol reduction)were investigated in the selective catalytic reduction of NOx by H2(H2-SCR).It was found that the preparation method exerted a significant effect on the activity of the Pd/TiO2 catalyst,and that the catalyst prepared by the polyethylene glycol reduction method exhibited the highest activity in the reduction of NOx.Characterization of the catalyst showed that,in the Pd/TiO2 catalyst prepared by the polyethylene glycol reduction method,the existing Pd species was Pd0,which is the desirable species for the H2-SCR of NOx.In situ DRIFTS studies demonstrated that over this catalyst,more chelating nitrite and monodentate nitrite species formed,both of which are reactive intermediates in the H2-SCR of NOx.All of these factors account for the high activity of Pd/TiO2 prepared by the polyethylene glycol reduction method.
基金supported by National Natural Science Foundation of China(21546014)the National Natural Science Foundation of Shanghai,China(14ZR1417800)
文摘In this study, the promotion effect of H2 pretreatment on the SCR performance of CeO2 catalyst was investigated based on the characterization results of XRD, H2-TPR, Raman and in situ DRIFT techniques.Lower crystallinity, higher reducibility and surface acidity can be found on CeO2-H catalyst. The results of DRIFT study reveal that the pretreatment of CeO2 catalyst with H2 can facilitate the adsorption of NH3 and NOx species, while the adsorbed NOx is basically inactive in the NH3-SCR reaction. Moreover, the reaction mechanism of the NH3-SCR reaction over CeO2 catalyst is not changed by H2 pretreatment,which is mainly under the control of Eley-Rideal（E-R） mechanism, The enhanced SCR performance of CeO2-H catalyst is mainly due to the promoted NH3 adsorption and the subsequent facilitation of SCR reaction through E-R pathway.
基金supported by the National Natural Science Foundation of China (21377010)the Fundamental Research Funds for the Central Universities (YS1401)the Program for New Century Excellent Talents in University,Ministry of Education,China (NCET-13-0650)
文摘A series of Ni,Sn and Ca modified Pd/TiO2-Al2O3catalysts were prepared by the incipient wetness impregnation method and their catalytic performance for the selective catalytic reduction of NOxby H2was evaluated.The results showed that the NOxconversion and N2selectivity were improved over Pd-Sn/TiO2-Al2O3and Pd-Ni/TiO2-Al2O3catalysts above 200°C.More importantly,the N2selectivity and high-temperature activity of Pd-Sn/TiO2-Al2O3catalyst was far superior to the single Pd/TiO2-Al2O3catalyst.The optimal Sn loading was 2 wt.%.X-ray diffraction(XRD)results showed that the interaction between Pd and Sn promotes the dispersion of Pd over TiO2-Al2O3.Temperature-programmed reduction(H2-TPR)results demonstrated that the addition of Sn contributes to the formation of Pd0and improving the redox property of Pd/TiO2-Al2O3.The additives of Ni and Sn also facilitated the absorption of NOxand the oxidation of NO to NO2,which play important roles in the selective catalytic reduction of NOxby hydrogen.
