HUSY zeolite modified by lanthanum: Effect of lanthanum introduction as a vanadium trap

Moreira, Carla R.; Homs, Narcı́s; Fierro, J.L.G.; Pereira, Marcelo Maciel; Piscina, Pilar Ramı́rez de la

doi:10.1016/j.micromeso.2010.04.017

Cited by 35 publications

(20 citation statements)

References 34 publications

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“…This inference is consistent with the results reported in the literature 37 . The formation of bridged hydroxyls has been reported for high exchange degrees when one sodalite cage contains two or more RE ions 38 39 . In this system, the H + ions from six Al-OH groups were replaced by two La 3+ , producing only one new H + ( Fig.…”

Section: Resultsmentioning

confidence: 96%

The effect of positioning cations on acidity and stability of the framework structure of Y zeolite

Deng

Zhang

Dong

et al. 2016

Sci Rep

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The investigation on the modification of NaY zeolite on LaHY and AEHY (AE refers Ca and Sr and the molar ratio of Ca and Sr is 1:1) zeolites was proformed by XRD, N2-physisorption (BET), XRF, XPS, NH3-TPD, Py-IR, hydrothermal stability, and catalytic cracking test. These results indicate that HY zeolite with ultra low content Na can be obtained from NaY zeolite through four exchange four calcination method. The positioning capability of La3+ in sodalite cage is much better than that of AE2+ and about 12 La3+ can be well coordinated in sodalite cages of one unit cell of Y zeolite. Appropriate acid amount and strength favor the formation of propylene and La3+ is more suitable for the catalytic cracking of cyclohexane than that of AE2+. Our results not only elaborate the variation of the strong and weak acid sites as well as the Brönsted and Lewis acid sites with the change of exchanged ion content but also explore the influence of hydrothermal aging of LaHY and AEHY zeolites and find the optimum ion exchange content for the most reserved acid sites. At last, the coordination state and stabilization of ion exchanged Y zeolites were discussed in detail.

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Section: Resultsmentioning

confidence: 96%

The effect of positioning cations on acidity and stability of the framework structure of Y zeolite

Deng

Zhang

Dong

et al. 2016

Sci Rep

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“…Thus, after modification and regulation of natural clinoptilolite, the pore diameter increased and the channels widened, which theoretically enabled more nitrogen and phosphates to enter the interior of the clinoptilolite . Although the aperture of the composite clinoptilolite decreased compared with that of the modified clinoptilolite, adsorption properties of ammonia removal were minimally affected …”

Section: Resultsmentioning

confidence: 98%

“…Furthermore, the holes on the composite clinoptilolite surface decreased compared with modified clinoptilolite. Therefore, lanthanum oxide on the surface of the clinoptilolite could have blocked several pores, which decreased the surface area of clinoptilolite . Nonetheless, the pore sizes of both modified and composite clinoptilolite were still relatively larger compared with the natural clinoptilolite…”

Section: Resultsmentioning

confidence: 99%

Effect of modification and regulation on physicochemical properties of clinoptilolite, as well as nitrogen and phosphates removal performance

et al. 2015

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Natural clinoptilolite was modified by NaCl-firing to produce modified clinoptilolite. Afterwards, the modified clinoptilolite was regulated by LaCl 3 to produce composite clinoptilolite. Modified clinoptilolite and composite clinoptilolite were used to adsorb ammonia-nitrogen and phosphates from wastewater. The modified clinoptilolite and composite clinoptilolite had high sorption efficiency and removal performance. The ammonia-nitrogen and phosphate removal rate of the modified clinoptilolite reached 96.46 % and the phosphate removal rate of the composite clinoptilolite reached 86.26 %. Furthermore, the structure was characterized by SEM, EDS, XRD, IR, and N 2 -porosimetry analyses. Results showed that the surface of modified clinoptilolite became loose and some pores appeared, which increased the specific surface area. In addition, total pore volume, micropore area and average pore width increased after modification by NaCl firing and LaCl 3 regulation, where in the micropore area exhibitedthe highest increase. The modification process did not change the overall skeletal structure and structural holes for both the modified clinoptilolite and the composite clinoptilolite. The main components were Si, Al, and O. The Na ion content of the modified clinoptilolite increased from 0.77 % to 2.45 % and the La ion content of composite clinoptilolite increased from 0 % to 2.52 %. The modification and regulation mechanisms were based on the Na þ replace Ca 2þ and Mg 2þ of clinoptilolite. Hydrous lanthanum oxide could be loaded only to the surface of clinoptilolites. In addition, the ion-exchange capacity of both the modified clinoptilolite and the composite clinoptilolite improved compared with natural clinoptilolite.

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“…When the standard precipitation method was used to prepare rare earth-containing zeolites, cations were preferentially located on the zeolite surface [13,16] However, no La 2 O 3 and CeO 2 phases were found in zeolite by TEM, and MAT results also proved that the rare earth cations moved to the sodalite cage of zeolite. Rietveld refinements were carried out for the XRD patterns of La-USY, Ce-USY and LaPO-USY to elucidate the differences between their zeolite crystalline structures.…”

Section: Resultsmentioning

confidence: 99%

“…They can diminish zeolite damage by decreasing the mobility of vanadium, with the efficiency depending on their types and introduction methods [13][14][15]. Generally, lanthanum is preferentially located on the surface of precipitation-derived zeolite [16], whereas it is preferentially located in the channels and cages of zeolite prepared by ionic exchange [17].…”

Section: Introductionmentioning

confidence: 99%

Effects of La2O3, CeO2 and LaPO4 introduction on vanadium tolerance of USY zeolites

Zhang

Cao

et al. 2015

Microporous and Mesoporous Materials

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HUSY zeolite modified by lanthanum: Effect of lanthanum introduction as a vanadium trap

Cited by 35 publications

References 34 publications

The effect of positioning cations on acidity and stability of the framework structure of Y zeolite

The effect of positioning cations on acidity and stability of the framework structure of Y zeolite

Effect of modification and regulation on physicochemical properties of clinoptilolite, as well as nitrogen and phosphates removal performance

Effects of La2O3, CeO2 and LaPO4 introduction on vanadium tolerance of USY zeolites

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