Crystallization of synthetic hydrotalcite under hydrothermal conditions

Kovanda, František; Koloušek, Dávid; Cílová, Zuzana Zlámalová; Hulı́nský, Václav

doi:10.1016/j.clay.2004.01.009

Cited by 109 publications

(85 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…MA0 had the smallest crystal size of 49 Å, clearly lower than crystal size of other MAs(95-113 Å). Those sizes were smaller than those in other researches, such as 230 Å [8] and 526 -1653 Å [9]. The differences in those sizes were because the reaction periods in this study were shorter than those of previous researches (18 h and 200 o C [8] and at 200 o C and 24 h [9]).…”

Section: Effect Of Reaction Period On Crystal Sizecontrasting

confidence: 50%

“…The sizes of single crystal were calculated following Debye-Scherrer formula [8] and summarized in Table 1. The data in Table 1 showed that crystal sizes increased with the increasing of reaction time.…”

Section: Effect Of Reaction Period On Crystal Sizementioning

confidence: 99%

“…The MAs were then dried at 110 o C for 24 hr and grinded by a ball grinner (Retsch MM200) and sieved (150 m mesh) to obtain the MA powder. The reaction time interval was chosen from the fact that the lowest reaction time for HT formation under low supersaturation condition in literature was 2 hr [8][9][10][11][12].…”

Section: Synthesis Of Ht Powder and Beadmentioning

confidence: 99%

See 2 more Smart Citations

Synthesis of Hydrotalcite Powder and Bead to Remove Arsenate

Thanh¹

2018

JST

View full text Add to dashboard Cite

The affecting factors on the synthesis of hydrotalcite (HT) powder and bead for effective arsenate removal were investigated. HTs with a ratio of Mg:Al = 2:1 (MA) were synthesized by the co-precipitation method at 70 o C with reaction times of 1 and 120 -300 min. The synthesis of MA with a reaction time of 1 min was done under high supersaturation condition, the others under low supersaturation conditions. The characteristics of MA were examined by X-ray diffraction (XRD), scanning electron microscopy, and nitrogen adsorption/desorption isotherms. According to the XRD patterns, pure HT was obtained for all tested conditions. With increasing reaction time from 1 to 300 min, the crystal size of MA increased from 4.9 to 11.3 μm, the surface area of MA increased from 9.3 to 71.4 m 2 /g. Batch-mode experiments showed that 1-min reaction time MA had the highest As(V) removal capacity. MA beads were separately synthesized using alginate and poly acrylamide (PAM) as binding agents. For alginate/MA, heat drying (110 o C) and freeze drying were applied to test the effect of these drying methods on the beads. The results showed that As(V) adsorption capacity of PAM/MA was the highest, closely followed by freeze drying/alginate/MA, much higher than that of heat drying/alginate/MA bead.

show abstract

Section: Effect Of Reaction Period On Crystal Sizecontrasting

confidence: 50%

Section: Effect Of Reaction Period On Crystal Sizementioning

confidence: 99%

See 1 more Smart Citation

Synthesis of Hydrotalcite Powder and Bead to Remove Arsenate

Thanh¹

2018

JST

View full text Add to dashboard Cite

show abstract

“…Different reduction behaviors could be observed depending on copper contents in oxides, except the sample OCMAO-800 which was not shown in figure 4. Kovanda et al [25] detected a prevailing peak around 700°C, which was assigned by the authors to the reduction of trace impurities in raw material [25]. Inconsistency in results of different authors might stem from different precursors selected and different purities of the Mg/Al oxide used.…”

Section: Tpr Analysis Of Icmao-800 Catalystsmentioning

confidence: 99%

Catalytic combustion of methane on novel catalysts derived from Cu-Mg/Al-hydrotalcites

Jiang

Hao

et al. 2005

Catal Lett

View full text Add to dashboard Cite

Novel Cu-Mg/Al mixed oxides (designated as i-CMAO-800) were prepared by calcinations of Cu-Mg/Al-hydrotalcites [(Cu 2þ +Mg 2þ )/Al 3þ = 3] at 800 C. Their performance for the catalytic combustion of methane was investigated. The oxides and their precursors were characterized by XRD, TG-DSC, TPR and N 2 adsorption/desorption techniques. The results showed that BET surface areas and the stability of the resultant oxides were greatly influenced by the copper contents in hydrotalcite precursors, bringing about difference in their activities for methane catalytic combustion. XRD results indicated that Cu was highly dispersed in hydrotalcite precursors in case of low copper contents, (Cu 40 wt%). For higher Cu contents, Cu(OH) 2 was formed, and, consequently, a separate phase of CuO was detected in the oxide catalysts after calcination. As indicated by the TG-DSC results, different decomposition behaviors were observed for various hydrotalcites. Thermal calcination promoted the formation of copper aluminates and segregation of CuO from the bulk phases. TPR results showed 15CMAO-800 has the highest reduction rate, and the catalytic activities of iCMAO-800 mixed oxides depend on both the reduction rates and the amounts of copper ions in mixed oxides. The catalyst 15-CMAO-800 showed the best performance.

show abstract

“…However, alternative methods providing well-crystallized materials have also been studied [23,24]. In particular, the use of microwaves during the synthesis of catalytic materials presented several advantages over conventional methods.…”

Section: Introductionmentioning

confidence: 99%

Co-Al Mixed Oxides Prepared via LDH Route Using Microwaves or Ultrasound: Application for Catalytic Toluene Total Oxidation

et al. 2015

View full text Add to dashboard Cite

Co6Al2HT hydrotalcite-like compounds were synthesized by three different methods: co-precipitation, microwaves-assisted and ultrasound-assisted methods. The mixed oxides obtained after calcination were studied by several techniques: XRD, TEM, H2-TPR and XPS. They were also tested as catalysts in the reaction of total oxidation of toluene. The physico-chemical studies revealed a modification of the structural characteristics (surface area, morphology) as well as of the reducibility of the formed mixed oxides. The solid prepared by microwaves-assisted synthesis was the most active. Furthermore, a relationship between the ratio of Co 2+ on the surface, the reducibility of the Co-Al mixed oxide and the T50 in toluene oxidation was demonstrated. This suggests a Mars Van Krevelen mechanism for toluene total oxidation on these catalysts.

show abstract

Crystallization of synthetic hydrotalcite under hydrothermal conditions

Cited by 109 publications

References 14 publications

Synthesis of Hydrotalcite Powder and Bead to Remove Arsenate

Synthesis of Hydrotalcite Powder and Bead to Remove Arsenate

Catalytic combustion of methane on novel catalysts derived from Cu-Mg/Al-hydrotalcites

Co-Al Mixed Oxides Prepared via LDH Route Using Microwaves or Ultrasound: Application for Catalytic Toluene Total Oxidation

Contact Info

Product

Resources

About