Structure–deactivation relationships in zeolites during the methanol–to-hydrocarbons reaction: Complementary assessments of the coke content

Rojo-Gama, Daniel; Signorile, Matteo; Bonino, Francesca; Bordiga, Silvia; Olsbye, Unni; Lillerud, Karl Petter; Beato, Pablo; Svelle, Stian

doi:10.1016/j.jcat.2017.04.015

Cited by 93 publications

(106 citation statements)

References 199 publications

(266 reference statements)

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“…In agreement with the observations reported by Pinard et al and Rojo-Gama et al, lower weight hydrocarbons such as alkylbenzenes were detected at retention times ranging from 7 to 17 min, while at higher retention time, heavier polycyclic hydrocarbons including alkylnaphthalene, alkylanthracenes, and phenanthrenes were found (Table 6) [58,59]. Due to the fact that the selected active phases, reaction temperature, and reaction time were kept the same for all catalytic oxidation tests [58,62], no significant change of coke composition was observed among the samples analyzed.…”

Section: Characterization Of the Used Catalystsupporting

confidence: 90%

“…In addition, differences in CO 2 yields were also evident between samples prepared on the same support, as shown in Figure 7. The discrepancy between benzene conversion and CO 2 yield and the absence of volatile byproducts of a reaction could be attributed to the formation of coke on the support's surface, as is commonly observed during the oxidation of benzene by other catalysts [58][59][60]. The formation of coke was studied and the results will be presented in Section 2.5.…”

Section: Characterization Of the Used Catalystmentioning

confidence: 99%

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A Comparative Study of Mn/Co Binary Metal Catalysts Supported on Two Commercial Diatomaceous Earths for Oxidation of Benzene

Tomatis

Wei

et al. 2018

Catalysts

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Two commercial diatomaceous earths were used as supports for the preparation of Mn/Co binary metal catalysts at different metal loads (5 to 10 wt % Mn and 5 to 15 wt % Co) by incipient wetness deposition. The activity of the prepared catalysts towards the complete oxidation of benzene to CO 2 and water was investigated between 100 and 400 • C. Raw supports and synthesized catalysts were characterized by XRD, N 2 physisorption, SEM-EDS, H 2 -TPR, and TPD. The purification treatment of food-grade diatomite significantly affected the crystallinity of this support while reducing its specific surface area (SSA). A loss of SSA, associated with the increase in the metal load, was observed on samples prepared on natural diatomite, while the opposite trend occurred with food-grade diatomite-supported catalysts. Metal nanoparticles of around 50 nm diameter were observed on the catalysts' surface by SEM analysis. EDS analysis confirmed the uniform deposition of the active phases on the support's surface. A larger H 2 consumption was found by TPR analysis of natural diatomite-based samples in comparison to those prepared at the same metal load on food-grade diatomite. During the catalytic oxidation experiment, over 90% conversion of benzene were achieved at a reaction temperature of 225 • C by all of the prepared samples. In addition, the formation of coke during the oxidation tests was demonstrated by TGA analysis and the soluble fraction of the produced coke was characterized by GC-MS.

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Section: Characterization Of the Used Catalystsupporting

confidence: 90%

Section: Characterization Of the Used Catalystmentioning

confidence: 99%

A Comparative Study of Mn/Co Binary Metal Catalysts Supported on Two Commercial Diatomaceous Earths for Oxidation of Benzene

Tomatis

Wei

et al. 2018

Catalysts

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“…Active hydrocarbon pool (HCP) species include olefins, poly‐methyl benzenes and poly‐methyl cyclopentenyl cations . Besides the “straight” reactions that these species suffer in the vicinity of acid sites – such as methylation, dealkylation, hydrogen transfer, cyclization and oligomerization, among others –, additional degradation reactions occur in order to form less active or even deactivating species such as poly‐methyl naphthalenes and ultimately coke . Thus, the sequenced individual steps of these reactions are (i) dissociation and methoxy species formation; (ii) initial C−C formation; (iii) formation of HCP species; (iv) methylation and scission to release light olefins; (v) secondary reactions of light olefins such as hydrogen transfer or condensation; and (vi) secondary reaction of HCP species to form coke.…”

Section: Introductionmentioning

confidence: 99%

Kinetic and Deactivation Differences Among Methanol, Dimethyl Ether and Chloromethane as Stock for Hydrocarbons

et al. 2019

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The conversions into hydrocarbons of methanol, dimethyl ether and chloromethane (MTH, DTH and CTH, respectively) on a H‐ZSM‐5 zeolite catalyst were compared trough ab‐initio calculations and experiments, using a fixed‐bed reactor and in‐situ FTIR spectroscopy. The molecular modelling of the reaction was performed using force field calculations. The nature and location of retained species were assessed by a combination of techniques. The experimental results of activity, product distribution and deactivation match these of the molecular modelling as the three reactions proceed through the dual‐cycle mechanism. However, the initiation, evolution and degradation of hydrocarbon pool species are kinetically different depending on the reactant. The reactions are faster in the order DTH>MTH≫CTH whereas the rate at which coke forms and grows (linked with the rate of deactivation) is in the order CTH≫DTH>MTH.

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“…However, the high amount of weak acid led to a sharp increase of C 9+ selectivity, while the selectivity of BTX was not significantly improved. Rich C 9+ content significantly increased the amount of carbon deposition, which accelerated the deactivation of the catalyst because the acidic site was covered by a large amount carbon deposition . Significant increase of BTX selectivity after acid‐treatment of HZSM‐5‐0.09 M, and the C 9+ only was 6.3 %, meanwhile, the selectivity of BTX accounted for 89.1 % in aromatics as shown in Figure e.…”

Section: Activity Evaluation Of Different Samples In Mta Reactionmentioning

confidence: 99%

Effect of the Post‐Treatment of HZSM‐5 on Catalytic Performance for Methanol to Aromatics

Dong

et al. 2020

ChemistrySelect

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The preparation of aromatic by methanol was the most effective way for rational utilization of resources. However, the catalyst for MTA reaction has not yet been successfully studied. Therefore, highly active and shape‐selective HZSM‐5 zeolite‐based catalysts were designed and synthesized by post‐treatments of desilication, dealumination, surface‐passivation and hydrothermal treatment tuning pore structure and acid amount and acid concentration of catalysts. XRD, SEM, TEM, BET, NH3‐TPD and Py‐IR were used for research and analysis the structure‐activity relationship between the catalysts and MTA reaction. The results showed that the total acid amount of catalyst shown a significant role in increasing the BTX selectivity. The selectivity of aromatics increased from 33 % to 58.1 % after hydrothermal treatment compared to the parent HZSM‐5 zeolite due to the decreased of total acid amount. Nevertheless the weak acid sites were crucial in increasing the p‐xylene selectivity. The selectivity of p‐xylene reached 63.8 % and 70.1 % after hydrothermal treatment and surface‐passivation due to the increased of weak acid sites, respectively. Modified HZSM‐5 zeolite‐base catalysts showed good application prospects in producing aromatics from methanol.

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Structure–deactivation relationships in zeolites during the methanol–to-hydrocarbons reaction: Complementary assessments of the coke content

Abstract: The author characterized fresh and partially deactivated samples, with the exception of the UV-Raman experiments. The author performed all the catalytic tests and he contributed in the planning of the experiments, interpretation of the results and preparation of the manuscript.

Cited by 93 publications

References 199 publications

A Comparative Study of Mn/Co Binary Metal Catalysts Supported on Two Commercial Diatomaceous Earths for Oxidation of Benzene

A Comparative Study of Mn/Co Binary Metal Catalysts Supported on Two Commercial Diatomaceous Earths for Oxidation of Benzene

Kinetic and Deactivation Differences Among Methanol, Dimethyl Ether and Chloromethane as Stock for Hydrocarbons

Effect of the Post‐Treatment of HZSM‐5 on Catalytic Performance for Methanol to Aromatics

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