Mg–Al hydrotalcite coating on zeolites for improved carbon dioxide adsorption

Othman, Mohd Roslee; Rasid, N.M.; Fernando, W.J.N.

doi:10.1016/j.ces.2005.09.011

Cited by 131 publications

(74 citation statements)

References 17 publications

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“…In addition, the improved activity in catalyst HT/rGO-10CFD may also be due to the highly dispersed nanosized HT platelets as observed in XRD and HRTEM analysis. Such observations would be consistent with the hypothesis that the number of active sites is determined by the lateral size of the HT platelets [5][6][7][8][9]11,12 .…”

Section: Acetone Self-condensationsupporting

confidence: 78%

“…Recently, other approaches have been developed based on the dispersion of the HT phase on different supports leading to HT nanocomposites. 5,6,7,8,9 The combination of (nano)carbon supports and HTs can lead to catalysts with improved properties such as high mechanical strength, surface area, thermal conductivity and chemical reactivity provided both by the carbon nanostructure and the HTs. For example, HT/CF nanocomposites obtained by growing MgAlHTs in situ on carbon fibers (CF) were efficient catalysts for the transesterification reaction of glycerol with diethyl carbonate into glycerol carbonate.…”

Section: Introductionmentioning

confidence: 99%

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Role of the synthesis route on the properties of hybrid LDH-graphene as basic catalysts

Álvarez

Tichit

Medina

et al. 2017

Applied Surface Science

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Layered double hydroxides (LDH or HT) or their derived mixed oxides present marked acid-base properties useful in catalysis, but they tend to agglomerate inducing a weak accessibility to the active sites. In this study we report the preparation and characterization of HT/Graphene (HT/rGO) nanocomposites as active and selective basic catalysts for the acetone condensation reaction. The graphene high specific surface area and structural compatibility with the HT allowed increasing the number and accessibility of the active sites and activity. Two series of HT/rGO nanocomposites with 0.5≤HT/rGO≤10 mass ratio were prepared by: i) direct HT coprecipitation in the presence of GO; ii) self-assembly of preformed HT with GO. The prepared HT/rGO nanocomposites were dried either in air at 80 °C or freeze-dried. A series of characterizations showed the great influence of the preparation method and HT/rGO mass ratio on both the nanocomposite structure and catalytic activity. An optimum activity was observed for a HT/rGO = 10 catalyst. Particularly, the highest catalytic activity was found in those nanocomposites obtained by coprecipitation and freeze dried (3 times more active than bulk HT) which can be connected to their structure with a better accessibility to the basic sites.2

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Section: Acetone Self-condensationsupporting

confidence: 78%

Section: Introductionmentioning

confidence: 99%

Role of the synthesis route on the properties of hybrid LDH-graphene as basic catalysts

Álvarez

Tichit

Medina

et al. 2017

Applied Surface Science

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“…5) according to the International Union of Pure and Applied Chemistry (IUPAC classification), which are typical of mesoporous and slitshaped materials [44]. The samples also exhibit the hysteresis type H 2 which is typical of clay minerals either of cationic or anionic types such as hydrotalcites [45].…”

Section: Resultsmentioning

confidence: 99%

Effect of the Ni/Al ratio of hydrotalcite-type catalysts on their performance in the methane dry reforming process

et al. 2015

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Hydrotalcite-type solids of the form NiAl-R, where R refers to the ratio of Ni to Al (R = 2, 3, 5, 8, and 10), were successfully synthesized following co-precipitation method at pH = 12. The obtained solids were calcined at 800°C, except for NiAl-R 2 where calcination was performed at temperatures ranging between 300 and 800°C. Following calcination, the resulting materials were evaluated for their catalytic activity and stability during the process of dry reforming of methane. Factors affecting the catalytic activity of the obtained materials such as the ratio R and calcination temperature were also studied. Prior to calcination, X-ray diffraction analyses clearly illustrated the typical hydrotalcite structure of the synthesized materials (when R B 5). On the other hand, calcination at various temperatures prompted decomposition of all solids to form NiO, with exception to NiAl-R 2 , which upon calcinations at 800°C was decomposed to form NiO and a second phase spinel containing NiAl 2 O 4 . The chemical composition of the obtained solids was determined by atomic absorption spectroscopy. Further characterization was performed using several techniques, including: surface area measurements (S BET ), scanning electron microscopy, Fourier transform infrared spectroscopy and thermogravimetric analysis. The reducibility of nickel species was studied via temperatureprogrammed reduction. The catalytic performance of the asprepared samples was studied for dry reforming of methane under atmospheric pressure at temperatures ranging between 400 and 700°C. The catalytic activity of the designed substances highlighted the importance of molar ratios i.e. Ni 2? / Al 3? on the success of the overall dry reforming of methane process. The catalytic activity of the synthesized materials was also found to be directly proportional to the ratio of Ni/ Al as well as the calcination temperature, with exception to NiAl-R 2 which was found to exhibit the highest activity of all. The latter observation was perhaps associated with the lower size of the crystalline particles in conjunction with the presence of a second phase containing NiAl 2 O 4 . In this study, it is shown that the calcination temperature has a significant effect on the catalytic property and the crystallite size of the metal.

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“…Regarding CO 2 adsorption and separation, it is of great significance to obtain high CO 2 adsorption capacity because the CO 2 adsorption behavior greatly influences the CO 2 separation and desorption processes on NaY particle and membrane. A number of efforts have been made to address CO 2 adsorption behavior via different adsorbents and techniques (Lee et al 2002;Harlick and Tezel 2004;Li and Tezel 2007;Siriwardane et al 2003;Jaramillo and Chandross 2004;Khelifa et al 2004;Li et al 2000Li et al , 2008Walton et al 2006;Maurin et al 2005;Gao et al 2004;Kusakabe et al 1997, Plant et al 2006Sebastian et al 2007;Chou and Chen 2004;Othman et al 2006;Zheng and Gu 1998). Yong et al (2002) reviewed the adsorption of CO 2 on different adsorbents at relatively high temperatures.…”

Section: Introductionmentioning

confidence: 99%

Adsorption of CO2 and N2 on synthesized NaY zeolite at high temperatures

Shao

Zhang

et al. 2009

Adsorption

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NaY zeolite particles with a high surface area of 723 m 2 /g were synthesized by a hydrothermal method. Adsorption isotherms of pure gases CO 2 and N 2 on the synthesized NaY particles were measured at temperatures 303, 323, 348, 373, 398, 423, 448 and 473 K and pressures up to 100 kPa. It was found that the adsorption isotherm of CO 2 on the synthesized zeolite is higher than that on other porous media reported in the literature. All measured adsorption isotherms of CO 2 and N 2 were fitted to adsorption models Sips, Toth, and UNILAN in the measured temperature/pressure range and Henry's law adsorption equilibrium constants were obtained for all three adsorption models. The adsorption isotherms measured in this work suggest that the NaY zeolite may be capable of capturing CO 2 from flue gas at high temperatures. In addition, isosteric heats of adsorption were calculated from these adsorption isotherms. It was found that temperature has little effect on N 2 adsorption, while it presents marked decrease for CO 2 with an increase of adsorbate loading, which suggests heterogeneous interactions between CO 2 and the zeolite cavity. KeywordsAdsorption isotherm · Isosteric heat of adsorption · Zeolite · CO 2 capture Nomenclature b Parameters for Sips model, kPa −1 c Parameters for UNILAN model, kPa DQ Standard deviation, % k Number of experimental data

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Mg–Al hydrotalcite coating on zeolites for improved carbon dioxide adsorption

Cited by 131 publications

References 17 publications

Role of the synthesis route on the properties of hybrid LDH-graphene as basic catalysts

Role of the synthesis route on the properties of hybrid LDH-graphene as basic catalysts

Effect of the Ni/Al ratio of hydrotalcite-type catalysts on their performance in the methane dry reforming process

Adsorption of CO2 and N2 on synthesized NaY zeolite at high temperatures

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