Influence of H 2 O and H 2 S on the composition, activity, and stability of sulfided Mo, CoMo, and NiMo supported on MgAl 2 O 4  for hydrodeoxygenation of ethylene glycol

Dabros, Trine Marie Hartmann; Gaur, Abhijeet; Pintos, Delfina García; Sprenger, Paul; Høj, Martin; Hansen, Thomas Willum; Studt, Felix; Gabrielsen, Jostein; Grunwaldt, Jan‐Dierk; Jensen, Anker Degn

doi:10.1016/j.apcata.2017.12.008

Cited by 35 publications

(68 citation statements)

References 101 publications

(167 reference statements)

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“…The MgAl2O4 support was chosen as a water tolerant alternative to γ-Al2O3, which is a dominant support for MoS2 based catalysts 1,47 . Details on the catalyst preparation and characterization composition was reported in previous work 48 . Figure 2.…”

Section: Sulfidation Set-upmentioning

confidence: 99%

“…During reaction, the sulfided sample was exposed to increasing ratios of H2O/H2S (30,100,190, and 300) in H2 with a constant total flow rate of 43 NmL/min and a holding time of 30 minutes for each H2O/H2S ratio. Further details about these steady state experiments were reported in previous work 48 .…”

Section: Sulfidation Set-upmentioning

confidence: 99%

“…Catalysts were exposed to different molar ratios of H2O/H2S (30,100,190, and 300) corresponding to 100-500 ppm H2S and 1.6-3.0% H2O. From performed activity tests 48 full conversion corresponded to a H2O/H2S ratio of ≈125 and ≈30 at 550 and 2200 ppm H2S, respectively. The ratios in the steady state experiments were chosen to fit 30 and 125, and then in the MES experiments it has been tried to go even higher to provoke the samples.…”

Section: Sulfidation Set-upmentioning

confidence: 99%

“…The details of the characterization of the sulfide phase prior to the steady state/MES experiment employing techniques of XAFS and TEM have been reported in previous work 48 . In case of sulfided NiMo catalyst (prepared as described herein) with 3.3 wt% Mo and a Ni/Mo molar ratio of 0.3, TEM results for particle size distribution based on >350 particles in > 45 images showed that the majority of the sulfided phase was present as ~4 nm monolayer MoS2-type slabs 48 (see figure S3). Structural parameters determined from fitting the Mo K-edge EXAFS spectra of the sulfided catalysts at 400 °C and the reference MoS2 are given in Tables S2-S4.…”

Section: Active Sulfide Phase Of Mo Como and Nimomentioning

confidence: 99%

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Probing the Active Sites of MoS₂ Based Hydrotreating Catalysts Using Modulation Excitation Spectroscopy

et al. 2019

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The reactive surface sites of MoS2 hydrotreating catalysts (unpromoted as well as Co-and Ni-promoted) supported on MgAl2O4 spinel were investigated with respect to the substitution of sulfur by oxygen using in-situ XAS coupled with modulation excitation spectroscopy (MES). Specifically, MES experiments were carried out by periodically cycling between a H2O and H2S containing hydrogen gas mixture at 400 °C. Due to the low fraction of SO exchange, conventional XANES and EXAFS data hardly showed any changes when these catalysts were exposed to increasing ratios of H2O to H2S in an H2 atmosphere. XANES and EXAFS data extracted at the Mo K-edge by MES analysis showed that for approximately 1 % of the Mo atoms, sulfur atoms are replaced by oxygen atoms when exposed to H2O, causing partial oxidation of these active sites. The reaction is reversible and Mo returns to its initial sulfide phase when H2O is removed and H2S is supplied in the feed. In case of Co-and Ni-promoted catalysts, the magnitude of SO exchange was found to be reduced, indicating the beneficial effect of promotion. MES at the Ni K-edge showed that Ni was oxidized during H2O exposure, which in turn delayed the Mo oxidation in the Ni-promoted catalyst. The structure of these catalysts under SO exchange were modelled using density functional theory (DFT) calculations, showing that the edge atoms are affected strongly. For all three catalysts, OH substitution is more favorable, while O substitution could be possible at high H2O pressure for unpromoted MoS2. Mo K-edge XANES spectra calculated using these simulated structures support the results obtained from the MES experiments. The presented approach using MES in combination with XAS and supported by DFT can be extended in general to catalysts under operando conditions, and is thus a useful tool for determination of the active site on an atomic-scale.

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Section: Sulfidation Set-upmentioning

confidence: 99%

Section: Sulfidation Set-upmentioning

confidence: 99%

Section: Sulfidation Set-upmentioning

confidence: 99%

Section: Active Sulfide Phase Of Mo Como and Nimomentioning

confidence: 99%

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Probing the Active Sites of MoS₂ Based Hydrotreating Catalysts Using Modulation Excitation Spectroscopy

et al. 2019

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“…The catalysts with the highest loading (NiMo#H and CoMo#H) aimed at reaching close to monolayer coverage of Mo in the calcined oxide phase precursors. For MgAl2O4, monolayer coverage is achieved at a loading of approximately 4 Mo atoms per nm 2 surface area [25], which ensures optimal spreading of oxidic molybdenum species formed during calcination [26] and results in the formation of small and highly dispersed MoS2 particles during sulfidation [27]. In addition, a four times lower loading (NiMo#L and CoMo#L) was used to study the role of loading and the interaction between the active phase and the support during HDO.…”

Section: Introductionmentioning

confidence: 99%

The Influence of Active Phase Loading on the Hydrodeoxygenation (HDO) of Ethylene Glycol over Promoted MoS2/MgAl2O4 Catalysts

et al. 2019

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The hydrodeoxygenation (HDO) of ethylene glycol over MgAl2O4 supported NiMo and CoMo catalysts with around 0.8 and 3 wt% Mo loading was studied in a continuous flow reactor setup operated at 27 bar H2 and 400 °C. A cofeed of H2S of typically 550 ppm was beneficial for both deoxygenation and hydrogenation and for enhancing catalyst stability. With 2.8-3.3 wt% Mo, a total carbon based gas yield of 80-100 % was obtained with an ethane yield of 36-50 % at up to 118 h on stream. No ethylene was detected. A moderate selectivity towards HDO was obtained, but cracking and HDO were generally catalyzed to the same extent by the active phase. Thus, the C2/C1 ratio of gaseous products was 1.1-1.5 for all prepared catalysts independent on Mo loading (0.8-3.3 wt%), but higher yields of C1-C3 gas products were obtained with higher loading catalysts. Similar activities were obtained from Ni and Co promoted catalysts. For the low loading catalysts (0.83-0.88 wt% Mo), a slightly higher hydrogenation activity was observed over NiMo compared to CoMo, giving a relatively higher yield of ethane compared to ethylene. Addition of 30 wt% water to the ethylene glycol feed did not result in significant deactivation. Instead, the main source of deactivation was carbon deposition, which was favored at limited hydrogenation activity and thus, was more severe for the low loading catalysts.

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The Hydrodeoxygenation of Glycerol over NiMoS_x: Catalyst Stability and Activity at Hydropyrolysis Conditions

et al. 2020

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Catalytic activity tests were run to elucidate the chemistry and catalyst stability for the hydrodeoxygenation of glycerol and other aliphatic oxygenates over a NiMoSx/Al2O3 catalyst at different pretreatments at hydropyrolysis conditions in a continuous flow reactor. Reactivity metrics were developed to quantify and compare the reactivity of NiMo for deoxygenation, hydrogenation, and C−C cleavage. Activity experiments showed sulfided NiMo and reduced NiMo catalysts had similar deoxygenation and hydrogenation activity for glycerol HDO at 400 °C and 270 psig H2 with the NiMoSx catalyst showing higher C−C cleavage activity. Without a sulfur co‐feed, both the NiMoSx and NiMoOx catalysts lost >40 % deoxygenation activity over 30 h time on stream. With a 2100 ppm H2S co‐feed the NiMoSx catalyst showed a 12 times decrease in the deactivation rate for deoxygenation and 6 time decrease in the deactivation rate for hydrogenation. The main products at high conversion were propylene, propane, ethylene, methane, CO, methanol, ethanol, and 1‐propanol. At low conversion, the major products were unsaturated allyl alcohol, acrolein, hydroxyacetone, and acetaldehyde. With no H2S co‐feed at short contact times, there was a significant amount of carbon loss possibly due to condensation reactions, while at 2100 ppm H2S in the feed, the carbon balance was 102.4 %. Temperature programmed oxidation of the spent NiMoSx catalysts after 30 h of glycerol HDO without an H2S co‐feed showed that one of the causes of deactivation was coking.

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Influence of H 2 O and H 2 S on the composition, activity, and stability of sulfided Mo, CoMo, and NiMo supported on MgAl 2 O 4 for hydrodeoxygenation of ethylene glycol

Cited by 35 publications

References 101 publications

Probing the Active Sites of MoS₂ Based Hydrotreating Catalysts Using Modulation Excitation Spectroscopy

Probing the Active Sites of MoS₂ Based Hydrotreating Catalysts Using Modulation Excitation Spectroscopy

The Influence of Active Phase Loading on the Hydrodeoxygenation (HDO) of Ethylene Glycol over Promoted MoS2/MgAl2O4 Catalysts

The Hydrodeoxygenation of Glycerol over NiMoS_x: Catalyst Stability and Activity at Hydropyrolysis Conditions

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Influence of H 2 O and H 2 S on the composition, activity, and stability of sulfided Mo, CoMo, and NiMo supported on MgAl 2 O 4 for hydrodeoxygenation of ethylene glycol

Cited by 35 publications

References 101 publications

Probing the Active Sites of MoS2 Based Hydrotreating Catalysts Using Modulation Excitation Spectroscopy

Probing the Active Sites of MoS2 Based Hydrotreating Catalysts Using Modulation Excitation Spectroscopy

The Influence of Active Phase Loading on the Hydrodeoxygenation (HDO) of Ethylene Glycol over Promoted MoS2/MgAl2O4 Catalysts

The Hydrodeoxygenation of Glycerol over NiMoSx: Catalyst Stability and Activity at Hydropyrolysis Conditions

Contact Info

Product

Resources

About

Probing the Active Sites of MoS₂ Based Hydrotreating Catalysts Using Modulation Excitation Spectroscopy

Probing the Active Sites of MoS₂ Based Hydrotreating Catalysts Using Modulation Excitation Spectroscopy

The Hydrodeoxygenation of Glycerol over NiMoS_x: Catalyst Stability and Activity at Hydropyrolysis Conditions