Catalytic behaviour of mesoporous metal phosphates in the gas-phase glycerol transformation

Lopez-Pedrajas, S.; Estévez, Rafael; Navarro, R.; Luna, Diego; Bautista, Felipa M.

doi:10.1016/j.molcata.2016.05.015

Cited by 16 publications

(17 citation statements)

References 33 publications

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“…Further increasing the calcination temperature facilitates the formation of orthorhombic α-AlPO 4 crystalline phase. Similar XRD results on AlPO 4 were observed by Liu et al 18 and Mohamed et al 19 Moreover, Lopez-Pedrajas et al 20 found that the amorphous AlPO 4 showed higher performance in the glycerol dehydration reaction than the other highly crystalline metal phosphates. Figure 2 illustrates the N 2 adsorption-desorption isotherms of AlP and AlP-T samples.…”

Section: Catalyst Characterizationsupporting

confidence: 77%

Catalytic Dehydration of Glycerol to Acrolein over Aluminum Phosphate Catalysts

Ding

Liu

et al. 2020

J. Braz. Chem. Soc.

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Gas phase conversion of glycerol to acrolein over a variety of aluminum phosphate (AlP) catalysts synthesized by a simple replacement reaction method with a variation in calcination temperature (300-700 °C, AlP-300, AlP-400, AlP-500, AlP-600, and AlP-700, respectively) has been investigated. The textural properties, acidities and coke contents of the samples were also determined. The catalysts were presented in an amorphous state when the AlP sample was calcined below 500 °C. Further increasing the calcination temperature promoted the formation of orthorhombic α-AlPO 4 crystal. The weak acid sites increased when the calcination temperature was raised from 300 to 500 °C. However, the weak acid sites decreased when the AlP was calcined above 500 °C. The acidity of the catalyst played a crucial role in the glycerol dehydration reaction. The maximum acrolein selectivity of 66% at 98% glycerol conversion was obtained over AlP-500 catalyst, due to the largest number of acid sites and appropriate textural properties. AlP-700 exhibited the lowest glycerol conversion, owing to the formation of orthorhombic α-AlPO 4 crystalline phase and the lowest amount of acid sites under high calcination temperature. The significant reduction in the acidity of the used sample led to a decrease of glycerol conversion.

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Section: Catalyst Characterizationsupporting

confidence: 77%

Catalytic Dehydration of Glycerol to Acrolein over Aluminum Phosphate Catalysts

Ding

Liu

et al. 2020

J. Braz. Chem. Soc.

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“…Typically, the reaction is carried out in the temperature range 250–350°C using aqueous glycerol as a feedstock, which is advantageous because glycerol is usually obtained mixed with water, as aforementioned. Furthermore, the reaction in gas phase generally occurs with better results than in liquid phase, as we have previously reported …”

Section: Introductionmentioning

confidence: 60%

“…Furthermore, we have also studied the influence of a second metal (Co, Cu, Cr, Fe) on the catalytic behaviour of aluminium phosphate. In previous work, we demonstrated the favourable effect of a metal with redox properties, such as vanadium, on the activity in the acrolein formation of AlPO 4 , whereas Ca did not have this effect.…”

Section: Introductionmentioning

confidence: 82%

“…More agreement seems to exist about the participation of the very strong acid sites, mainly Brönsted sites, in the coke formation, which provokes catalyst deactivation, mainly by pore blocking. The microporous materials being more quickly and widely deactivated than those proving to be meso or macroporous …”

Section: Introductionmentioning

confidence: 99%

“…A study on the formation and nature of coke over time on stream, has also been carried out. In this respect, an off‐line analysis of the effluent from the reactor was carried out in order to avoid deposits of unidentified compounds, which were responsible for some obstruction of the reaction system lines, as previously reported …”

Section: Introductionmentioning

confidence: 99%

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Insight into the gas‐phase glycerol dehydration on transition metal modified aluminium phosphates and zeolites

Lopez-Pedrajas

Estévez

Blanco-Bonilla

et al. 2017

J of Chemical Tech & Biotech

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BACKGROUND: The production of biodiesel has notably increased in recent years, with glycerol as the main by-product, an important raw material in the production of value-added products. Those obtained by dehydration are especially important. RESULTS: Gas phase dehydration of glycerol has been tested on mesoporous AlPO 4 and modified AlPO 4 , with a small amount (1 wt%) of a transition metal (Co, Cu, Cr, Fe), calcined at 450 ∘ C and 650 ∘ C, and compared with some commercial zeolites (HZSM and HY). All the catalysts were active in the reaction, the phosphates showing better catalytic behaviour than the zeolites. The main products of the reaction were acrolein and hydroxyacetone. CONCLUSIONS:The positive effect of metal on the catalytic behaviour of AlPO 4 in the dehydration has been verified, attaining the maximum yield to acrolein (54%) on AlCoPO650 with 50 mg of catalyst and 280 ∘ C of reaction temperature. Furthermore, the phosphates did not suffer deactivation after 22 h reaction, whereas the zeolites suffered a strong loss of activity (around 70%) due to blockage of the micropores by coke. Moreover, the yield to acrolein decreased with time, while the yield to hydroxyacetone increased. An E 2 mechanism for the acrolein formation and E 1 for the hydroxyacetone formation have been proposed.

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Progress of the Catalytic Deactivation of H‐ZSM‐5 Zeolite in Glycerol Dehydration

et al. 2021

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Glycerol conversion into value-added chemicals has received much attention due to the prospect of increasing the biodiesel industry's profitability. The dehydration of glycerol is one of the most explored reactions in the valorization of glycerol, and the zeolite H-ZSM-5 is one of the furthermost used structures. In this study, several characterization techniques were used to investigate the detailed aging of coke in spent H-ZSM-5 zeolites after their use in the gas-phase glycerol dehydration to produce acrolein. The carbonaceous deposits formed almost totally in the first minutes of the reaction. They rapidly got trapped inside the pores, hampering the accessibility to active sites and the zeolite's full catalytic action. Two types of coke were formed during the reaction: polyglycols, on the external surface, and aromatics, inside the pores, representing the majority (~98 wt.%) of the carbonaceous compounds. Besides, aromatic compounds age over time, becoming bulkier and more deficient in hydrogen. We also found a correlation between the amount of coke, its size, accessibility to the acid active sites, and changes in crystallographic parameters of the zeolite with the presence of coke.

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Catalytic behaviour of mesoporous metal phosphates in the gas-phase glycerol transformation

Cited by 16 publications

References 33 publications

Catalytic Dehydration of Glycerol to Acrolein over Aluminum Phosphate Catalysts

Catalytic Dehydration of Glycerol to Acrolein over Aluminum Phosphate Catalysts

Insight into the gas‐phase glycerol dehydration on transition metal modified aluminium phosphates and zeolites

Progress of the Catalytic Deactivation of H‐ZSM‐5 Zeolite in Glycerol Dehydration

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