Pd/YZ-Al2O3 （Y and Zr modified Al2O3, and hereafter, labelled as A1） catalysts with 4 wt% additive CeO2 and/or La2O3 were prepared and characterized by X-ray photoelectron spectroscopy （XPS）, NO-temperature progra...Pd/YZ-Al2O3 （Y and Zr modified Al2O3, and hereafter, labelled as A1） catalysts with 4 wt% additive CeO2 and/or La2O3 were prepared and characterized by X-ray photoelectron spectroscopy （XPS）, NO-temperature programmed desorption （NO-TPD）, Nz-adsorption/desorption （Branauer-Emmet-Teller BET method）, X-ray diffraction （XRD） and CO-chemisorption. Catalytic activities for CH4, CO and NO conversion were tested in a gas mixture simulated the emissions from natural gas vehicles （NGVs） operated under stoichiometric conditions. The results indicated that all catalysts exhibited excellent catalytic performances for CH4 and CO oxidation and the promoting effect of CeO2 or La2O3 was significant for NO conversion. XPS results showed that the electron density around Pd was increased by CeO2 and/or La2O3, the binding energy of Pd 3d decreased as the order： Pd/Al 〉 Pd/Ce/Al 〉 Pd/La/Al 〉 Pd/CeLa/Al. The electron-rich Pd showed Rh-like catalytic properties which exhibited good activity for the reduction of NO. NO-TPD results showed that the addition of CeO2 and/or La2O3 increased NO adsorption on surface, and promoted the conversion of NO.展开更多
Natural gas, whose primary constituent is methane, has been considered a convincing alternative for the growth of the energy supply worldwide. Adsorbed natural gas （ANG）, the most promising methane storage method, h...Natural gas, whose primary constituent is methane, has been considered a convincing alternative for the growth of the energy supply worldwide. Adsorbed natural gas （ANG）, the most promising methane storage method, has been an active field of study in the past two decades. ANG constitutes a safe and low-cost way to store methane for natural gas vehicles at an acceptable energy density while working at substantially low pressures （3.5- 4.0 MPa）, allowing for conformable store tank. This work serves to review the state-of-the-art development reported in the scientific literature on adsorbents, adsorption theories, ANG conformable tanks, and related technolo- gies on ANG vehicles. Patent literature has also been searched and discussed. The review aims at illustrating both achievements and problems of the ANG technologies-based vehicles, as well as forecasting the development trends and critical issues to be resolved of these technologies.展开更多
近年来,天然气汽车(natural gas vehicles,NGVs)尾气净化三效催化剂的研究主要集中在具有高分散性的负载型贵金属催化剂。利用金属有机骨架(MOFs)模板法制备了纳米结构的CeCoO_(x)(M)复合氧化物作为载体,并与传统溶胶-凝胶法(SG)制备的...近年来,天然气汽车(natural gas vehicles,NGVs)尾气净化三效催化剂的研究主要集中在具有高分散性的负载型贵金属催化剂。利用金属有机骨架(MOFs)模板法制备了纳米结构的CeCoO_(x)(M)复合氧化物作为载体,并与传统溶胶-凝胶法(SG)制备的铈钴氧化物比较,探究了贵金属Pd在2种催化剂载体上的分散状态及对其催化性能的影响。结果表明,以CeCo-MOFs材料为前驱体衍生制备的Pd/CeCoO_(x)(M)催化剂其CO、NO、CH4三效催化性能相比溶胶-凝胶法制备的相同组成Pd/CeCoO_(x)(SG)催化剂,相同转化率下催化温度低了约100℃,具有更高的低温活性。以CeCo-MOFs为前驱体衍生制备的铈钴复合氧化物晶体粒子更小,晶相结构均匀,具有更大的比表面积,促进了Pd组分分散状态的提高,也丰富了催化剂的氧空位和结构缺陷,显著提高了催化剂的低温三效催化性能。利用MOFs前驱体热分解得到的复合氧化物可以作为三效催化贵金属活性组分分散的良好材料。展开更多
基金supported by the Key Program of National Natural Science Foundation of China (20333030)the National High Technology Research and Development Program of China (863 Program, No. 2006AA06Z347)the National Natural Science Foundation of China (No. 20773090)
文摘Pd/YZ-Al2O3 （Y and Zr modified Al2O3, and hereafter, labelled as A1） catalysts with 4 wt% additive CeO2 and/or La2O3 were prepared and characterized by X-ray photoelectron spectroscopy （XPS）, NO-temperature programmed desorption （NO-TPD）, Nz-adsorption/desorption （Branauer-Emmet-Teller BET method）, X-ray diffraction （XRD） and CO-chemisorption. Catalytic activities for CH4, CO and NO conversion were tested in a gas mixture simulated the emissions from natural gas vehicles （NGVs） operated under stoichiometric conditions. The results indicated that all catalysts exhibited excellent catalytic performances for CH4 and CO oxidation and the promoting effect of CeO2 or La2O3 was significant for NO conversion. XPS results showed that the electron density around Pd was increased by CeO2 and/or La2O3, the binding energy of Pd 3d decreased as the order： Pd/Al 〉 Pd/Ce/Al 〉 Pd/La/Al 〉 Pd/CeLa/Al. The electron-rich Pd showed Rh-like catalytic properties which exhibited good activity for the reduction of NO. NO-TPD results showed that the addition of CeO2 and/or La2O3 increased NO adsorption on surface, and promoted the conversion of NO.
文摘Natural gas, whose primary constituent is methane, has been considered a convincing alternative for the growth of the energy supply worldwide. Adsorbed natural gas （ANG）, the most promising methane storage method, has been an active field of study in the past two decades. ANG constitutes a safe and low-cost way to store methane for natural gas vehicles at an acceptable energy density while working at substantially low pressures （3.5- 4.0 MPa）, allowing for conformable store tank. This work serves to review the state-of-the-art development reported in the scientific literature on adsorbents, adsorption theories, ANG conformable tanks, and related technolo- gies on ANG vehicles. Patent literature has also been searched and discussed. The review aims at illustrating both achievements and problems of the ANG technologies-based vehicles, as well as forecasting the development trends and critical issues to be resolved of these technologies.
文摘近年来,天然气汽车(natural gas vehicles,NGVs)尾气净化三效催化剂的研究主要集中在具有高分散性的负载型贵金属催化剂。利用金属有机骨架(MOFs)模板法制备了纳米结构的CeCoO_(x)(M)复合氧化物作为载体,并与传统溶胶-凝胶法(SG)制备的铈钴氧化物比较,探究了贵金属Pd在2种催化剂载体上的分散状态及对其催化性能的影响。结果表明,以CeCo-MOFs材料为前驱体衍生制备的Pd/CeCoO_(x)(M)催化剂其CO、NO、CH4三效催化性能相比溶胶-凝胶法制备的相同组成Pd/CeCoO_(x)(SG)催化剂,相同转化率下催化温度低了约100℃,具有更高的低温活性。以CeCo-MOFs为前驱体衍生制备的铈钴复合氧化物晶体粒子更小,晶相结构均匀,具有更大的比表面积,促进了Pd组分分散状态的提高,也丰富了催化剂的氧空位和结构缺陷,显著提高了催化剂的低温三效催化性能。利用MOFs前驱体热分解得到的复合氧化物可以作为三效催化贵金属活性组分分散的良好材料。
