On the kinetics of methanol dehydration to dimethyl ether on Zr-loaded P-containing mesoporous activated carbon catalyst

Palomo, José; Rodríguez-Cano, Miguel Ángel; Rodríguez‐Mirasol, J.; Cordero, Tomás

doi:10.1016/j.cej.2019.122198

Cited by 33 publications

(24 citation statements)

References 60 publications

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“…Activated carbons are amorphous carbon materials, mainly characterized by a well-developed porous texture [1]. They are widely used in many different applications including (1) adsorption, both in gas and liquid phases [2][3][4], (2) catalysis, mostly as supports of the active phases [5][6][7][8][9] but also as bulk catalysts [10][11][12][13], and (3) in electrochemical or energy storage applications for use as supercapacitors [14][15][16][17][18]. There is currently a reborn interest in research of the synthesis, characterization, and applications of activated carbons, as shown by recent reviews and the high number of publications on this topic that can be found in the technical literature [19][20][21][22][23][24].…”

Section: Activated Carbonsmentioning

confidence: 99%

Review on Activated Carbons by Chemical Activation with FeCl3

et al. 2020

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This study reviews the most relevant results on the synthesis, characterization, and applications of activated carbons obtained by novel chemical activation with FeCl3. The text includes a description of the activation mechanism, which compromises three different stages: (1) intense de-polymerization of the carbon precursor (up to 300 °C), (2) devolatilization and formation of the inner porosity (between 300 and 700 °C), and (3) dehydrogenation of the fixed carbon structure (>700 °C). Among the different synthesis conditions, the activation temperature, and, to a lesser extent, the impregnation ratio (i.e., mass ratio of FeCl3 to carbon precursor), are the most relevant parameters controlling the final properties of the resulting activated carbons. The characteristics of the carbons in terms of porosity, surface chemistry, and magnetic properties are analyzed in detail. These carbons showed a well-developed porous texture mainly in the micropore size range, an acidic surface with an abundance of oxygen surface groups, and a superparamagnetic character due to the presence of well-distributed iron species. These properties convert these carbons into promising candidates for different applications. They are widely analyzed as adsorbents in aqueous phase applications due to their porosity, surface acidity, and ease of separation. The presence of stable and well-distributed iron species on the carbons’ surface makes them promising catalysts for different applications. Finally, the presence of iron compounds has been shown to improve the graphitization degree and conductivity of the carbons; these are consequently being analyzed in energy storage applications.

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Section: Activated Carbonsmentioning

confidence: 99%

Review on Activated Carbons by Chemical Activation with FeCl3

et al. 2020

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“…During the stabilization process, PAN chains begin to crosslink, allowing the newly composed polymer structure to resist high temperature processing. [50][51][52][53] Oxidative stabilization is crucial and responsible for the resulting shrinkage behavior of the nanofiber mats. 54 During stabilization and carbonization processes, chemical and entropic shrinkage occurs.…”

Section: Resultsmentioning

confidence: 99%

Needleless electrospun polyacrylonitrile/konjac glucomannan nanofiber mats

Mamun

Trabelsi

Klöcker

et al. 2020

Journal of Engineered Fibers and Fabrics

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In this study we report for the first time about the preparation of polyacrilontrile (PAN)/konjac glucomannan (KGM) nanofiber mats, needleless electrospinning from the low-toxic solvent dimethyl sulfoxide (DMSO) and the formation of carbon nanocomposites. Konjac glucomannan is a biopolymer and renewable, environmentally friendly raw material and a well-known polysaccharide, which is non-toxic and biocompatible material and is extracted from the Amorphophallus konjac plant. The addition of poloxamer in electrospinning PAN/KGM solution resulted in the reduction of membrane areas and decrease of beads in nanofibers. The concentration of 1.5% or 0.5% of konjac glucomannan in PAN/KGM nanofiber mats was not detected to affect the morphology of the nanofiber mats. The PAN/KGM nanofiber mats received oxidative stabilization and subsequent carbonization. It could be observed that after the oxidative stabilization process the average diameter of PAN/KGM nanofibers increased and after carbonization decreased compared to stabilized nanofibers. Alternative renewable raw materials such as KGM electrospun with synthetic polymers offer the possibility to reduce the environmental impact and are the alternative to new technical materials and lowers the cost of carbon materials. The combination of PAN with konjac glucomannan and the properties of both polymers open up a wide range of applications for the PAN/KGM nanofiber mats and carbon nanocomposites produced in this study, for example, for pharmaceutical and biomedical applications, as absorbents for the removal of pollutants in wastewater and as filter media for air purification, as well as for optical and chemical sensors.

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“…With this goal, the reaction pathways previously reported for this catalyst at different experimental conditions were considered. In this sense, Palomo et al following a Langmuir-Hinshelwood mechanism, proposed a fourstep mechanism for DME production, in which two methanol molecules were sequentially adsorbed in the active sites, and then reacted with each other to produce DME and adsorbed water, which was desorbed to regenerate the initial active sites [28]. On the other hand, at higher temperatures (between 450 • C and 550 • C), two adsorbed methanol molecules could also react through a six-member ring, producing methane and an intermediate that mainly evolved into coke and water or CO and hydrogen [29].…”

Section: Kinetic Study Including Deactivationmentioning

confidence: 99%

“…However, when oxygen was not present in the reaction medium, conversion decayed to a residual value of around 7% after only 20 min [14]. To overcome this problem, zirconium was added to those P-containing activated carbons, obtaining surface zirconium phosphate species [28,29]. The latter catalyst achieved a stable 50% yield to DME for more than 72 h at 350 • C, without the release of any other byproducts [30].…”

Section: Introductionmentioning

confidence: 99%

“…With regard to the Zr-loaded P-containing carbon catalyst, a mechanism for methanol dehydration at low temperatures was proposed, which is also based on an LH mechanism, where two methanol molecules were adsorbed on one active site, with different adsorption enthalpies, and considering the competitive adsorption of water on the active sites [28]. When that Zr-loaded P-containing carbon was submitted to higher temperatures, a different reaction pathway seemed to take place, because some coke formation was observed.…”

Section: Introductionmentioning

confidence: 99%

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A Kinetic Model Considering Catalyst Deactivation for Methanol-to-Dimethyl Ether on a Biomass-Derived Zr/P-Carbon Catalyst

et al. 2022

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A Zr-loaded P-containing biomass-derived activated carbon (ACPZr) has been tested for methanol dehydration between 450 and 550 °C. At earlier stages, methanol conversion was complete, and the reaction product was mainly dimethyl ether (DME), although coke, methane, hydrogen and CO were also observed to a lesser extent. The catalyst was slowly deactivated with time-on-stream (TOS), but maintained a high selectivity to DME (>80%), with a higher yield to this product than 20% for more than 24 h at 500 °C. A kinetic model was developed for methanol dehydration reaction, which included the effect of the inhibition of water and the deactivation of the catalyst by coke. The study of stoichiometric rates pointed out that coke could be produced through a formaldehyde intermediate, which might, alternatively, decompose into CO and H2. On the other hand, the presence of 10% water in the feed did not affect the rate of coke formation, but produced a reduction of 50% in the DME yield, suggesting a reversible competitive adsorption of water. A Langmuir–Hinshelwood reaction mechanism was used to develop a kinetic model that considered the deactivation of the catalyst. Activation energy values of 65 and 51 kJ/mol were obtained for DME and methane production in the temperature range from 450 °C to 550 °C. On the other hand, coke formation as a function of time on stream (TOS) was also modelled and used as the input for the deactivation function of the model, which allowed for the successful prediction of the DME, CH4 and CO yields in the whole evaluated TOS interval.

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On the kinetics of methanol dehydration to dimethyl ether on Zr-loaded P-containing mesoporous activated carbon catalyst

Cited by 33 publications

References 60 publications

Review on Activated Carbons by Chemical Activation with FeCl3

Review on Activated Carbons by Chemical Activation with FeCl3

Needleless electrospun polyacrylonitrile/konjac glucomannan nanofiber mats

A Kinetic Model Considering Catalyst Deactivation for Methanol-to-Dimethyl Ether on a Biomass-Derived Zr/P-Carbon Catalyst

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