The effect of various treatment conditions on natural zeolites: Ion exchange, acidic, thermal and steam treatments

Ateş, Ayten; Hardacre, Christopher

doi:10.1016/j.jcis.2012.01.017

Cited by 127 publications

(80 citation statements)

References 69 publications

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“…The natural and modified samples were characterized by XRF, XRD, BET, FTIR, DR-UV-Vis, NH 3 -TPD and TGA and the results obtained were reported in Ref. [29]. The chemical composition of the zeolites was investigated using X-ray fluorescence (XRF, Shimadzu 1700).…”

Section: Preparation Of Catalystsmentioning

confidence: 99%

“…The natural and modified samples were treated at low temperature (LT), high temperature (HT) and steam (ST) conditions and characterized by XRF, XRD, BET, FTIR, DR-UV-Vis, NH 3 -TPD and TGA. The detailed investigation for the modification and characterization of natural zeolites was reported by Ates and Hardacre [29]. In this study, the catalytic performances of the natural and modified natural zeolites for the direct decomposition of N 2 O and the selective reduction (SCR) of N 2 O with NH 3 were performed at varying reaction temperatures under the steady-state conditions.…”

Section: Introductionmentioning

confidence: 97%

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Effect of pre-treatment and modification conditions of natural zeolites on the decomposition and reduction of N2O

Ateş

2014

Reac Kinet Mech Cat

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The decomposition of N 2 O and reduction of N 2 O with NH 3 on natural and modified zeolites were studied by a steady state reaction. Two different natural zeolites having different phase compositions were modified by ion exchange (0.5 M NH 4 NO 3 ) and acid leaching (1 M HCl) and treated under low temperature, high temperature and steam conditions. It was observed that the surface modification of natural zeolites depends strongly on their structure and composition. The modification of zeolites by ion exchange and acid leaching increases the decomposition activity of N 2 O because of the formation of isolated iron and Fe-O-Al species. However, these modifications insignificantly affect the reduction of N 2 O with NH 3 . High temperature and steam treatments lead to dealumination, loss of crystallinity, sintering of phases and the formation of amorphous material in zeolites, resulting in a significant decrease in the decomposition and reduction activity of N 2 O. The kinetic evaluation for N 2 O decomposition predicts that the rate-limiting step is the recombinative desorption of molecular oxygen.

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Section: Preparation Of Catalystsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

Effect of pre-treatment and modification conditions of natural zeolites on the decomposition and reduction of N2O

Ateş

2014

Reac Kinet Mech Cat

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“…Acid treatment on natural zeolite not only removes impurities that block the pores of zeolite such as metal oxides compounds but also progressively eliminate cations and finally dealuminate the structure as the strength and duration of treatment increases [28]. Dealumination leads to the breaking of Al-O bonds, as well as a loss of crystallinity, particularly at low Si/Al ratios [29]. Thus, the negative charge on zeolite surface become reduced consequently the amount of exchangeable cations in zeolite become fewer.…”

Section: Activation Of Zeolitementioning

confidence: 99%

Carbon Paste Electrode Hexadecyltrimethylammonium Bromide Modified Natural Zeolite for Chromium(vi) Detection

2013

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“…These treatments enhance the pozzolanic reactivity of zeolites through de-alumination, resulting in a loss of crystallinity. Correspondingly, the silicon/aluminium ratio of untreated clinoptilolite significantly increases after treatment (Ates and Hardacre, 2012;Cakicioglu-Ozkan and Ulku, 2005;Elaiopoulos et al, 2010;Misaelides et al, 1996;Zhang et al, 2002). Furthermore, under alkali conditions and elevated temperatures, zeolites undergo eventual decomposition of their crystalline structure as a result of silicon leaching (Bonilla et al, 2009).…”

Section: Introductionmentioning

confidence: 98%

Self-repairing properties of OPC clinker/natural zeolite blend in water and alkali carbonate environments at 270°C

Pyatina

Sugama

Ronne

et al. 2018

Advances in Cement Research

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The 10 d recoveries of the mechanical properties and crack sealing of an ordinary Portland cement (OPC) clinker/natural zeolite (ferrierite (Fer)) blend modified or unmodified with silica were tested at 270°C in water and alkali carbonate environments. The recoveries of the samples depended on their modification with silica and the curing environment, but were more than 100% after repeated damage under some test conditions. The mechanical properties and phase compositions of recovered samples were evaluated by compressive strength measurements and x-ray diffraction, differential thermogravimetric analyses, Fourier transform infrared analyses and scanning electron microscopy coupled with energy dispersive x-ray spectroscopy. The sealing of 0·25 mm wide and $2 mm deep cracks was visualised with a three-dimensional optical microscope. Fer decomposed under high-temperature alkaline conditions with the release of hydrolysates that, along with the hydrating clinker, participated in the formation of new phases contributing to strength recoveries. These phases included crystalline magnesium and aluminiumcontaining silicates, calcium and carbonated calcium silicates and amorphous hydrates. Crack sealing was complete for the silica-modified samples and partial for unmodified ones cured in carbonate environments. The sealing was very poor for samples cured in water. The main sealing phases included crystalline and amorphous silica, hightemperature-stable zeolites and talc mineral.

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The effect of various treatment conditions on natural zeolites: Ion exchange, acidic, thermal and steam treatments

Cited by 127 publications

References 69 publications

Effect of pre-treatment and modification conditions of natural zeolites on the decomposition and reduction of N2O

Effect of pre-treatment and modification conditions of natural zeolites on the decomposition and reduction of N2O

Carbon Paste Electrode Hexadecyltrimethylammonium Bromide Modified Natural Zeolite for Chromium(vi) Detection

Self-repairing properties of OPC clinker/natural zeolite blend in water and alkali carbonate environments at 270°C

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