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首页> 外文期刊>Catalysis science & technology >Effects of support pre-calcination on the NO_x storage and reduction performance of Pt-BaO/Al2O3 catalysts
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Effects of support pre-calcination on the NO_x storage and reduction performance of Pt-BaO/Al2O3 catalysts

机译：支持预估计对NO_X存储和降低PT-BAO/AL2O3催化剂的影响

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摘要

Effects of the crystalline structure and surface property of the Al2O3 support on the NO_x storage and reduction (NSR) performance of Pt-BaO/Al2O3 catalysts were studied using catalysts prepared from a series of Al2O3 samples obtained by varying the calcination temperature of an AI(OH)3 hydrogel in the range of 450-1000 °C (referred to as the preolcination temperature, PC!). The texture, crystalline structure and surface acidity of the Al2O3(PCT) supports were measured employing nitrogen adsorption-desorption, XRD, NH3-TPD and IR spectroscopy of adsorbed pyridine, respectively. The Al2O3(PCT) samples showed a gradual ordering of the γ-Al2O3 phase when increasing the PCT from 450 to 800 °C, and a phase transition from the y- to 9-Al2O3 phase upon further increasing the PCT to 1000 °C. The surface density of Lewis acid sites of the Al2O3(PC7) samples exhibited a maximum at PCT in the range of 800-900 °C. The NSR performance of Pt-BaO/Al2O3 catalysts derived from the Al2O3(PCT) samples was studied under cyclic lean/rich conditions. The numbers of NO_x stored and reduced on the Pt-BaO/Al2O3(PCT) catalysts showed similar volcano-type dependencies on PCT, peaking at PCT= 800 °C The origins of the support PCT effect were discussed in the light of Pt particle size, the nature of BaO sites and Pt-BaO synergy. It was found that the increase in the crystallinity of the γ-Al2O3 phase and the surface acid site density of the supporting Al2O3 samples would result in improved proximity and synergy between Pt and BaO sites, leading to much more efficient NSR Pt-BaO/Al2O3 catalysts.
机译：使用从AI（通过改变AI的钙化温度获得的一系列AL2O3样品）制备的催化剂，研究了Al2O3支持的结构结构和表面性能对PT-BAO/AL2O3催化剂的NO_X存储和还原性能（NSR）性能的影响（NSR） OH）3水凝胶在450-1000°C的范围内（称为预氯化温度，PC！）。分别采用氮吸附 - 解吸收，XRD，NH3-TPD和IR光谱法分别测量了Al2O3（PCT）支撑的质地，结构和表面酸度。当将PCT从450增加到800°C时，Al2O3（PCT）样品显示γ-Al2O3相的逐渐排序，并且在将PCT进一步增加到1000°C的情况下从Y-至9-Al2O3相跃迁。 Al2O3样品（PC7）样品的路易斯酸位点的表面密度在800-900°C范围内显示出最大值。在循环瘦/富含条件下研究了源自Al2O3（PCT）样品的PT-BAO/AL2O3催化剂的NSR性能。在PT-BAO/AL2O3（PCT）催化剂上存储和减少的NO_X的数量显示出相似的火山型依赖性对PCT的依赖性，在PCT = 800°C峰值峰值pct效果的起源是在PT粒径的光中讨论的。 ，BAO站点和PT-BAO协同作用的性质。发现发现γ-AL2O3相的结晶度和支撑AL2O3样品的表面酸位点密度将导致PT和BAO位点之间的接近和协同作用，从而导致更有效的NSR PT PT-BAO/AL2O3催化剂。

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