Understanding the enhancement of catalytic performance for olefin cracking: Hydrothermally stable acids in P/HZSM-5

Xue, Nianhua; Chen, Xiangke; Nie, Lei; Guo, Xuefeng; Ding, Weiping; Chen, Yi; Gu, Min; Xie, Zaiku

doi:10.1016/j.jcat.2007.02.022

Cited by 216 publications

(179 citation statements)

References 39 publications

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“…At the same time, strong acid declined dramatically, which resulted in a reduction of inactivation rate. These results could be explained by the interaction of promoter species with parent zeolite framework, which resulted in masking the acid sites and forming new acid sites [25,26]. The strong acid sites provide the main active sites for methanol dehydration, so it can enhance coke formation and catalyst deactivation.…”

Section: Acid Propertymentioning

confidence: 99%

Effect of magnesium modification over H-ZSM-5 in methanol to propylene reaction

et al. 2015

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H-ZSM-5-based catalyst is a recognized catalyst which is particularly selective towards the formations of light olefins in the methanol reaction. A series of H-ZSM-5 (SiO 2 /Al 2 O 3 = 38) modified with different amounts of magnesium have been investigated. All the samples were characterized by X-ray diffraction instrument (XRD), temperature-programmed desorption of NH 3 (NH 3 -TPD) and Fourier Transform Infrared Spectoscopy (FT-IR). The results indicated that the impregnation of H-ZSM-5 (SiO 2 /Al 2 O 3 = 38) zeolite with various magnesium loading amount significantly affected the strength of acid sites and decreased the concentration of both weak and strong acid sites. As a result of modification, magnesium mainly interacted with strong Brønsted acid sites, thus generated new medium strong acid sites and enhanced the yield of propylene. The optimum acid property for methanol to propylene (MTP) reaction was gotten over 4.0 Mg-ZSM-5 (4.0 wt% Mg) zeolite catalyst. The maximum yield of propylene was 10.62 wt% over 4.0 Mg-ZSM-5 zeolite catalyst by the 30 min on stream. Coke which was mostly formed on strong Brønsted acid sites, would cause the catalysts deactivation, so the reduction of strong Brønsted acid sites could enhance the catalytic stability.

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Section: Acid Propertymentioning

confidence: 99%

Effect of magnesium modification over H-ZSM-5 in methanol to propylene reaction

et al. 2015

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“…27 Al nuclei at a sample spinning rate of 8 kHz. For recording solid-state 31 P NMR spectra, high-power proton decoupling (HPDEC) was utilized.…”

Section: Characterization Techniquesmentioning

confidence: 99%

“…For recording solid-state 31 P NMR spectra, high-power proton decoupling (HPDEC) was utilized. Before the 27 Al and 31 P MAS NMR measurements, the samples under study were hydrated by exposure to the atmosphere over an aqueous solution of Ca(NO 3 ) 2 at ambient temperature. Before the 1 H MAS NMR studies, the sample materials were dehydrated at 673 K in vacuum (pressure below 10 -2 Pa) for 12 h. Some samples were loaded with 70 mbar acetonitrile-d 3 (99.9 % deuterated; ACROS) using a vacuum line and evacuated at 293 K for 1 h. Subsequently, the sample materials were sealed and kept in glass tubes until their transfer into MAS NMR rotors inside a glove box purged with dry nitrogen gas.…”

Section: Characterization Techniquesmentioning

confidence: 99%

Effect of Phosphate Modification on the Brønsted Acidity and Methanol‐to‐Olefin Conversion Activity of Zeolite ZSM‐5

Dyballa

Klemm

Weitkamp

et al. 2013

Chemie Ingenieur Technik

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Phosphate-modified ZSM-5 zeolites were studied by standard characterization techniques and solid-state nuclear magnetic resonance spectroscopy, and in the methanol-to-olefin (MTO) conversion. Considering the physicochemical properties of the ZSM-5 zeolites, the most important effects of the phosphate modification are a deposition of polyphosphates in the pore system and a decrease of the acid site density, but not of the acid site strength. The significant increase in the selectivity to C 2 -C 4 alkenes and the decrease of C 5+ formation in the MTO reaction for a phosphate coverage of about 5 wt % are explained by extra-framework phosphate species near the crossing intersections of the ZSM-5 pore system, which hinder the formation of large intermediates and reaction products.

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“…Recently, a schematic mechanism for the phosphorus interaction with H-ZSM-5 was suggested as shown in Fig. 3(c) 17) . Two zeolitic hydroxyls are condensed with one phosphate molecule after calcination in air leading to a decrease in the number of OH groups on P modification.…”

Section: Catalyst Characterizationmentioning

confidence: 99%

“…However, the acidity of the strong acid sites was still lower than that on the untreated H-ZSM-5 due to the partial dealumination. 22) and (c) Proposed by Xue et al 17) Fig. 4 NH 3 -TPD Profiles of the H-ZSM-5 and P-HZSM-5 Catalysts selectivities for hydrocarbons were calculated from the product amounts excluding aromatic compounds.…”

Section: M T O R E a C T I O N S O V E R H -Z S M -5 A N D P-hzsm-5mentioning

confidence: 99%

High Propylene Selectivity in Methanol-to-olefin Reaction over H-ZSM-5 Catalyst Treated with Phosphoric Acid

雄一朗

憲和

et al. 2010

J. Jpn. Petrol. Inst.

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H-ZSM-5 zeolite was treated with phosphorus acid by impregnating H-ZSM-5 with aqueous solutions of phosphoric acid at various concentrations. H-ZSM-5 (P-HZSM-5) modified with phosphoric acid was used as a catalyst for the methanol-to-olefin reaction. The molar ratios of P/Si and Si/Al in H-ZSM-5 and P-HZSM-5 were measured by EDX analysis. The Si/Al molar ratios of P-HZSM-5 increased with higher concentration of H3PO4 in the solution, which might be caused by partial dealumination of H-ZSM-5 by the H3PO4 treatment. The P/Si molar ratio of P-HZSM-5 after washing was proportional to the H3PO4 concentrations in the aqueous solutions. The remaining phosphorus species after the washing must be strongly adsorbed by interaction with the pore surface of H-ZSM-5 zeolite. The P-HZSM-5 catalyst showed very high propylene selectivity up to 57% with methanol conversion of 100%. Furthermore, catalyst stability was significantly improved for the P-HZSM-5 catalysts. Ammonia TPD spectra showed that the strong acid sites of H-ZSM-5 disappeared after the phosphoric acid treatment. Consequently, the formation of aromatics and coke was inhibited, resulting in higher light olefin selectivity and catalyst stability.

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Understanding the enhancement of catalytic performance for olefin cracking: Hydrothermally stable acids in P/HZSM-5

Cited by 216 publications

References 39 publications

Effect of magnesium modification over H-ZSM-5 in methanol to propylene reaction

Effect of magnesium modification over H-ZSM-5 in methanol to propylene reaction

Effect of Phosphate Modification on the Brønsted Acidity and Methanol‐to‐Olefin Conversion Activity of Zeolite ZSM‐5

High Propylene Selectivity in Methanol-to-olefin Reaction over H-ZSM-5 Catalyst Treated with Phosphoric Acid

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