CHEMICAL ENGINEERING JOURNAL
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2024
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IF 13.3
Yimin Zhang,Meiyu Liu,Chengming Huang,Hang Zhang,Jian Zheng,Yucai Qin,Ye Yang,Yi Mei,Yun Zu
Zn-based catalysts are promising for direct propane dehydrogenation (PDH) to propylene owing to their cheaper and environment-friendly features but are subjected to serious depletion of active Zn component under working conditions. Herein, we successfully open a “black box” for the origin of active Zn speciations confined within the silicalite-1 (S-1) zeolite by thermogravimetric-mass spectrometry analysis and in-situ Fourier transform infrared spectroscopy. Guided by this, single-site, multinuclear and nanometer hydroxylated ZnO x species are separately encapsulated into the channels of S-1 zeolite by the controllable transformation of intermediate Zn(OH) x with assistant of vicinal- and nest-silanols. Delightfully, synthetic m -ZnO x @S-1 catalyst enables enviable propylene formation rate (50.8 mmol∙g cat −1 ∙h −1 ) and propylene selectivity (>96 %) in the PDH reaction. Most importantly, initial activity revives as before and without Zn loss after 7 regeneration cycles. This exceptional PDH performance is benefited from low-coordination and extra-stable multinuclear ZnO x species that can greatly lower the dehydrogenation barrier, favoring the PDH pathway to further produce propylene and hydrogen. These findings elucidate the potential of Zn-based zeolite catalysts for the development of PDH reaction and afford value-filled opportunities in alternative PDH catalyst optimization.
研究领域:
催化化学
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材料科学
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DOI
高影响因子
CATALYSIS TODAY
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2024
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IF 5.2
Longyu Wang,Na Wang,Suohe Yang,Guangxiang He,Haiyan Liu,Xianghai Meng,Chunming Xu,Zhichang Liu,Haibo Jin
A diverse suite of Zn-SAPO-34 catalysts was synthesized employing three distinct methodologies for the incorporation of zinc species: thermal ion exchange, wet impregnation, and physical mixing. The catalysts were characterized using various analytical techniques including XRD, FT-IR, BET, SEM, XRF, XPS, NH 3 -TPD, and Py-IR, to elucidate the crystal structure, morphology, surface acidity, and the presence of zinc species within the catalysts. The study showed that the method of zinc introduction markedly impacts the physicochemical properties of the catalysts. Different approaches to introducing zinc species significantly influence the acid strength and type on the catalyst surface, with variations in the existing states of zinc across the catalysts. Specifically, zinc species introduced via thermal ion exchange coexist as ZnOH + and ZnO within the catalyst, whereas those from wet impregnation and physical mixing are individually present as either ZnOH + or ZnO. Furthermore, the study examined the catalytic performance of these Zn-SAPO-34 catalysts in the dehydration of fructose to produce 5-hydroxymethylfurfural (HMF). Catalysts prepared via thermal ion exchange exhinited superior performance, achieving an remarkable HMF yield of 94.6 %. Additionally, in situ infrared technology was used to investigate the effect of zinc species introduction on the fructose dehydration process, indicating suggesting that the introduction of zinc species enhances the transformation of fructose molecules.
研究领域:
催化化学
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材料科学
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产品关联
DOI
高影响因子
JOURNAL OF COLLOID AND INTERFACE SCIENCE
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2020
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IF 7.489
Xiaoqiang Wang,Yue Liu,Zhongbiao Wu
Low-medium temperature NH 3 -SCR technology has been applied for years in municipal solid wastes incineration (MSWI) to control the emissions of nitrogen oxides . Unlike coal-fired flue gases , the tail gas from MSWI contains high levels of heavy metals in fly ash, especially the zinc species, which may harm SCR catalysts. As such, in this paper, the deactivation mechanism of different zinc species (ZnO, ZnSO 4 and ZnCl 2 ) on the Sb-CeZr 2 O x catalysts and the co-effects of zinc species and gas-phase pollutants (including SO 2 and HCl) were investigated. The experimental results indicated that the deactivation rate of various poisoning zinc species was in the order of ZnCl 2 > ZnSO 4 > ZnO. Moreover, the interactions between zinc and antimony species would disrupt the structure of the Sb-Ce mixed oxides to decrease the redox ability, consequently suppressing the ammonia activation and NO adsorption. Furthermore, such damaging effects on catalyst structures would promote the formation of bulk-like sulfate species in the presence of SO 2 , resulting in a decreased mobility of surface oxygen species, which significantly decrease the sulfur resistance. However, the presence of HCl did not show an evident co-effect on the Zn poisoned sample owing to the limited coverage of the chlorine deposition.
研究领域:
环境科学
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催化化学
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DOI
高影响因子
FUEL
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2024
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IF 6.7
Guosheng Li,Yu Ding,Xiaohan Li,Kunhong Li,Xinrui Yin,Liang Zhao,Shenyong Ren,Chunming Xu,Baojian Shen
Regulation of electronic structure of metal active phase for catalysts has been known as efficient in promoting its catalytic activity; however, manipulating the activity of catalysts via controllable metal active phase electronic structure is still challenging. A non-equilibrium electronic structure Fe-based bulk catalyst has been developed via controllably adding P species, where the non-equilibrium electronic structure of Fe species is formed through the electron transfer from the Zn species through the P electronic channel. As a result, the catalytic activity of the modified Fe-based bulk catalysts has increased by 24.4–50.4%. Meanwhile, the sulfurization degree (SD) of the modified Fe-based bulk catalysts has increased by 5.6–25.9%. In addition, the HDS reaction rate constant ( k HDS ) has increased by about 2.0 times, and the DDS reaction rate constant ( k DDS ) has increased by about 2.4 times. The P modifying can regulate the directional transfer of unpaired free electrons between Fe and Zn species to form a more non-equilibrium electronic structure of Fe species, which can reduce the energy barrier of the C–S bond adsorbed on the P-modified Fe-based bulk catalysts. Importantly, the P species can be used as an active site to adsorb S-containing compounds in the modified Fe-based bulk catalysts, which is conducive to generating more coordinatively unsaturated sites (CUSs). The former can promote the formation of the more non-equilibrium electronic structure of Fe species, and the latter can adjust the adsorption active site of S-containing on the catalyst surface. Therefore, an electron transfer channel is formed among Fe, Zn, and P species, and another one is formed among Fe, P, and S-containing compounds, which form a dual-channel electron transfer behavior. Furthermore, the specific surface area, total pore volume, and reducibility of the modified Fe-based bulk catalysts have also shown varying degrees of improvement via the controllable addition of P species.
研究领域:
催化
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材料科学
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化学工程
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DOI
高影响因子
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