采用无定形海泡石(SEP)负载Co基催化剂进行乙醇蒸汽重整制氢,是一种绿色、可持续的制氢工艺。考虑乙醇蒸汽重整制氢具有结构敏感性,煅烧温度是调控催化剂关键物化性质的重要参数。多种表征分析表明,金属–载体相互作用受煅烧温度介导,...采用无定形海泡石(SEP)负载Co基催化剂进行乙醇蒸汽重整制氢,是一种绿色、可持续的制氢工艺。考虑乙醇蒸汽重整制氢具有结构敏感性,煅烧温度是调控催化剂关键物化性质的重要参数。多种表征分析表明,金属–载体相互作用受煅烧温度介导,以不同Co物种赋存形态具现。随着煅烧温度的升高,钴赋存形态由初始的钴氧化物到钴页硅酸盐,再到钴铝尖晶石的转变。乙醇蒸汽重整制氢实验表明,Co/SEP-600催化剂活性较优,并维持50 h稳定性,得益于其页硅酸盐多孔结构和Co0纳米颗粒精细尺寸。进一步提高煅烧温度将削弱Co/SEP-700的稳定性和Co/SEP-800的活性。因此,Co与海泡石骨架Si、Al原子之间的相互作用决定了催化剂的乙醇蒸汽重整制氢反应性,而煅烧温度则可调节催化剂活性和稳定性。此外,大尺寸Co0颗粒上沉积大量石墨碳,如Co/SEP-400,归因于其金属–载体相互作用较弱;而Co/SEP-800中具有难还原性的钴铝尖晶石相和强金属–载体相互作用,仅出现少量积碳。Hydrogen production over ethanol steam reforming proceeding on Co-based catalysts is a green and sustainable hydrogen production process. Considering the structure sensitivity of hydrogen production, the calcination temperature is an important parameter to regulate the key physico-chemical properties of catalysts. Characterization analysis shows that metal-support interaction is mediated by the calcination temperature. It is embodied in the form of different Co speciation. With the increase of calcination temperature, the cobalt occurrence form changes from the initial cobalt oxide to Co-phyllosilicate, and then to Co-Al spinel. The experiment results showed that Co/SEP-600 catalyst had a better activity and maintained a 50 h stability, which benefited from porous structure and fine Co0 nanoparticles of Co-phyllosilicate. A further increase of the calcination temperature would weaken the stability of Co/SEP-700 and the activity of Co/SEP-800. Therefore, the interaction between Co and the Si or Al framework atoms of sepiolite determines the reforming reactivity of catalysts, while the calcination temperature can adjust the activity and stability of catalysts. In addition, abundant graphite carbon deposited on large-size Co0 particles of Co/SEP-400 is attributed to the weak metal-support interaction, while Co/SEP-800 featured with irreducible Co-Al spinel and strong metal-support interaction and showed only a small carbon deposition.展开更多
We demonstrate for the first time that a short time of microwave irradiation on the oxide precursor of a Cu/ZnO/Al2O3 catalyst can provide unique opportunity for tailoring the microstructure and activity of the cataly...We demonstrate for the first time that a short time of microwave irradiation on the oxide precursor of a Cu/ZnO/Al2O3 catalyst can provide unique opportunity for tailoring the microstructure and activity of the catalyst for methanol steam reforming. It is shown by in situ XRD that a considerable increase in the microstrain of Cu nanocrystals could be achieved in the catalysts processed by microwave irradiation for 310 min, which correlates well with the enhanced CH3OH conversion as observed on the corresponding samples. The present work also confirms that although the high specific surface area of Cu is a prerequisite for catalytic activity, it does not account for the observed changes in activity and selectivity alone without taking bulk microstructural changes into account.展开更多
A number of nanostructured carbon materials were proposed as new effective promoters for preparing modified Cu/ZnO/Al 2O 3 catalyst system for efficient hydrogen production from methanol steam reforming. Compared to t...A number of nanostructured carbon materials were proposed as new effective promoters for preparing modified Cu/ZnO/Al 2O 3 catalyst system for efficient hydrogen production from methanol steam reforming. Compared to the catalysts modified by other type of carbon materials, the ACF-promoted catalyst prepared via carbonate-coprecipitation method exhibit the highest performance in the low-temperature steam reforming of methanol. It was suggested that the intrinsic high surface area nature of ACF material may favor the generation of modified catalysts with a high surface area and improved component dispersion, thus leading to improved performance for methanol steam reforming.展开更多
放射性废树脂蒸汽重整反应器通常采用流化床结构。树脂在流化床中达到较好的流态化是保证反应持续、提高处理效率、实现树脂减容和核素包容的关键因素。为对流化床中树脂的流态化情况进行分析优化,建立了鼓泡流化床树脂蒸汽重整的计算模...放射性废树脂蒸汽重整反应器通常采用流化床结构。树脂在流化床中达到较好的流态化是保证反应持续、提高处理效率、实现树脂减容和核素包容的关键因素。为对流化床中树脂的流态化情况进行分析优化,建立了鼓泡流化床树脂蒸汽重整的计算模型,针对废树脂蒸汽重整中试流化床采用流体体积(volume of fluid,VOF)模型模拟流化床内树脂蒸汽多相流动状态。重点分析了不同流化操作气速下的床层压降、床高空隙率分布,获得了不同操作气速下的树脂流化状态。数值计算分析及后续测试结果表明,采用VOF模型可较好用于废树脂鼓泡流化床的计算模拟;操作气速增加,树脂的流化状态产生明显变化;当操作气速控制在0.7 m/s左右时,该中试流化床可达到最佳的流化状态。在此操作气速下开展了多组树脂蒸汽重整试验,最终获得的树脂重整平均减容倍数达到了6以上,在流化床内构件未发现树脂聚团,结焦现象,树脂在流化床形成了较好的流化状态。展开更多
文摘采用无定形海泡石(SEP)负载Co基催化剂进行乙醇蒸汽重整制氢,是一种绿色、可持续的制氢工艺。考虑乙醇蒸汽重整制氢具有结构敏感性,煅烧温度是调控催化剂关键物化性质的重要参数。多种表征分析表明,金属–载体相互作用受煅烧温度介导,以不同Co物种赋存形态具现。随着煅烧温度的升高,钴赋存形态由初始的钴氧化物到钴页硅酸盐,再到钴铝尖晶石的转变。乙醇蒸汽重整制氢实验表明,Co/SEP-600催化剂活性较优,并维持50 h稳定性,得益于其页硅酸盐多孔结构和Co0纳米颗粒精细尺寸。进一步提高煅烧温度将削弱Co/SEP-700的稳定性和Co/SEP-800的活性。因此,Co与海泡石骨架Si、Al原子之间的相互作用决定了催化剂的乙醇蒸汽重整制氢反应性,而煅烧温度则可调节催化剂活性和稳定性。此外,大尺寸Co0颗粒上沉积大量石墨碳,如Co/SEP-400,归因于其金属–载体相互作用较弱;而Co/SEP-800中具有难还原性的钴铝尖晶石相和强金属–载体相互作用,仅出现少量积碳。Hydrogen production over ethanol steam reforming proceeding on Co-based catalysts is a green and sustainable hydrogen production process. Considering the structure sensitivity of hydrogen production, the calcination temperature is an important parameter to regulate the key physico-chemical properties of catalysts. Characterization analysis shows that metal-support interaction is mediated by the calcination temperature. It is embodied in the form of different Co speciation. With the increase of calcination temperature, the cobalt occurrence form changes from the initial cobalt oxide to Co-phyllosilicate, and then to Co-Al spinel. The experiment results showed that Co/SEP-600 catalyst had a better activity and maintained a 50 h stability, which benefited from porous structure and fine Co0 nanoparticles of Co-phyllosilicate. A further increase of the calcination temperature would weaken the stability of Co/SEP-700 and the activity of Co/SEP-800. Therefore, the interaction between Co and the Si or Al framework atoms of sepiolite determines the reforming reactivity of catalysts, while the calcination temperature can adjust the activity and stability of catalysts. In addition, abundant graphite carbon deposited on large-size Co0 particles of Co/SEP-400 is attributed to the weak metal-support interaction, while Co/SEP-800 featured with irreducible Co-Al spinel and strong metal-support interaction and showed only a small carbon deposition.
文摘We demonstrate for the first time that a short time of microwave irradiation on the oxide precursor of a Cu/ZnO/Al2O3 catalyst can provide unique opportunity for tailoring the microstructure and activity of the catalyst for methanol steam reforming. It is shown by in situ XRD that a considerable increase in the microstrain of Cu nanocrystals could be achieved in the catalysts processed by microwave irradiation for 310 min, which correlates well with the enhanced CH3OH conversion as observed on the corresponding samples. The present work also confirms that although the high specific surface area of Cu is a prerequisite for catalytic activity, it does not account for the observed changes in activity and selectivity alone without taking bulk microstructural changes into account.
文摘A number of nanostructured carbon materials were proposed as new effective promoters for preparing modified Cu/ZnO/Al 2O 3 catalyst system for efficient hydrogen production from methanol steam reforming. Compared to the catalysts modified by other type of carbon materials, the ACF-promoted catalyst prepared via carbonate-coprecipitation method exhibit the highest performance in the low-temperature steam reforming of methanol. It was suggested that the intrinsic high surface area nature of ACF material may favor the generation of modified catalysts with a high surface area and improved component dispersion, thus leading to improved performance for methanol steam reforming.
文摘放射性废树脂蒸汽重整反应器通常采用流化床结构。树脂在流化床中达到较好的流态化是保证反应持续、提高处理效率、实现树脂减容和核素包容的关键因素。为对流化床中树脂的流态化情况进行分析优化,建立了鼓泡流化床树脂蒸汽重整的计算模型,针对废树脂蒸汽重整中试流化床采用流体体积(volume of fluid,VOF)模型模拟流化床内树脂蒸汽多相流动状态。重点分析了不同流化操作气速下的床层压降、床高空隙率分布,获得了不同操作气速下的树脂流化状态。数值计算分析及后续测试结果表明,采用VOF模型可较好用于废树脂鼓泡流化床的计算模拟;操作气速增加,树脂的流化状态产生明显变化;当操作气速控制在0.7 m/s左右时,该中试流化床可达到最佳的流化状态。在此操作气速下开展了多组树脂蒸汽重整试验,最终获得的树脂重整平均减容倍数达到了6以上,在流化床内构件未发现树脂聚团,结焦现象,树脂在流化床形成了较好的流化状态。
