Reactivities, reaction networks, and kinetics in high-pressure catalytic hydroprocessing

Girgis, Michael; Gates, Bruce C.

doi:10.1021/ie00057a001

Cited by 895 publications

(734 citation statements)

References 76 publications

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“…The OA capped Pt demonstrated severe deactivation for ethylene hydrogenation and the low activity for CO oxidation. Since amine groups are known poisons for precious metal catalysts 24,25 , these results are not surprising.…”

Section: Origins Of Capping Agent Induced Catalytic Differencesmentioning

confidence: 99%

Effect of organic capping layers over monodisperse platinum nanoparticles upon activity for ethylene hydrogenation and carbon monoxide oxidation

Kuhn

Tsung

Huang

et al. 2009

Journal of Catalysis

171

150

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The influence of oleylamine (OA), trimethyl tetradecyl ammonium bromide (TTAB), and polyvinlypyrrolidone (PVP) capping agents upon the catalytic properties of Pt/silica catalysts was evaluated. Pt nanoparticles of 1.5 nm in size were synthesized by the same procedure (ethylene glycol reduction under basic conditions) with the various capping agents added afterwards for stabilization.Before examining catalytic properties for ethylene hydrogenation and CO oxidation, the Pt NPs were deposited onto mesoporous silica (SBA-15) supports and characterized by transmission electron microscopy (TEM), H 2 chemisorption, and elemental analysis (ICP-MS). PVP and TTAB capped Pt yielded mass normalized reaction rates that decreased with increasing pretreatment temperature and was attributed to partial coverage of the Pt surface with decomposition products from the organic capping agent. Once normalized to the Pt surface area, similar intrinsic activities were obtained regardless of the pretreatment temperature, which indicated no influence on the nature of active sites. Consequently, a chemical probe technique using intrinsic activity for ethylene hydrogenation was demonstrated as an acceptable method for estimating the metallic surface areas of Pt. Amine (OA) capping exhibited a detrimental influence on the catalytic properties as severe deactivation and low activity were observed for ethylene hydrogenation and CO oxidation, respectively. These results were consistent with amine groups being strong poisons for Pt surfaces and revealed the need to consider the effects of capping agents to stabilize nanoparticles on the catalytic properties.

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Section: Origins Of Capping Agent Induced Catalytic Differencesmentioning

confidence: 99%

Effect of organic capping layers over monodisperse platinum nanoparticles upon activity for ethylene hydrogenation and carbon monoxide oxidation

Kuhn

Tsung

Huang

et al. 2009

Journal of Catalysis

171

150

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“…[10] by integrating over the contact time τ or, as we choose, use a numerical approach. In the latter the reactor was divided into 10 segments in which the thiophene concentration was assumed constant.…”

Section: Reaction Kinetics 323-773 Kmentioning

confidence: 99%

“…The thiophene partial pressure at the end of each segment could easily be obtained by using Eq. [10]. As input value for the thiophene pressure P T the outlet concentration of the former segment was used etc.…”

Section: Reaction Kinetics 323-773 Kmentioning

confidence: 99%

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Structure and Nature of the Active Sites in CoMo Hydrotreating Catalysts Conversion of Thiophene

Leliveld¹,

Dillen²,

Geus³

et al. 1998

Journal of Catalysis

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The performance of sulfided (Co)Mo/alumina catalysts was studied in the conversion of thiophene between 423 and 773 K at atmospheric pressure. Reaction orders for thiophene, H 2 , and H 2 S were determined at several temperatures. The reaction order in thiophene increases with rising temperature, indicating a LangmuirHinshelwood mechanism. Beyond 550 K the conversion curve deviates from pseudo-first-order kinetics, demonstrating the influence of the surface coverage of thiophene on the reaction rate. Above 673 K the reaction rate rises exponentially with temperature which can be ascribed to the presence of a second type of active site that is only active at high temperatures. These catalytic data can be combined with recent structural studies using EXAFS spectroscopy to derive an activity-structure relation. It is proposed that at low temperature the active sites are terminal sulphur vacancies on the Co-promotor atom. In addition around 673 K a second type of sites becomes active, which is believed to consist of bridging sulphur vacancies in between Co and Mo atoms on the MoS 2 edges.

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“…First, their combustion directly causes the formation of nitrogen oxides (NO x ), which contribute to acid rain and depletion of the ozone layer (Kirimura et al 1999). Second, nitrogencontaining aromatic compounds presence can cause poisoning of refining catalysts, resulting in a decrease in yield (Girgis and Gates 1991;Williams and Chisti 2001). Carbazole directly affects the refining process by its conversion into basic derivatives during cracking, which allows it to adsorb to the active sites of the cracking catalyst.…”

Section: Industrial and Medical Importance Of Carbazolementioning

confidence: 99%

Properties, environmental fate and biodegradation of carbazole

2017

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The last two decades had witnessed extensive investigation on bacterial degradation of carbazole, an Nheterocyclic aromatic hydrocarbon. Specifically, previous studies have reported the primary importance of angular dioxygenation, a novel type of oxygenation reaction, which facilitates mineralization of carbazole to intermediates of the TCA cycle. Proteobacteria and Actinobacteria are the predominant bacterial phyla implicated in this novel mode of dioxygenation, while anthranilic acid and catechol are the signature metabolites. Several studies have elucidated the degradative genes involved, the diversity of the car gene clusters and the unique organization of the car gene clusters in marine carbazole degraders. However, there is paucity of information regarding the environmental fate as well as industrial and medical importance of carbazole and its derivatives. In this review, attempt is made to harness this information to present a comprehensive outlook that not only focuses on carbazole biodegradation pathways, but also on its environmental fate as well as medical and industrial importance of carbazole and its derivatives.

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Reactivities, reaction networks, and kinetics in high-pressure catalytic hydroprocessing

Cited by 895 publications

References 76 publications

Effect of organic capping layers over monodisperse platinum nanoparticles upon activity for ethylene hydrogenation and carbon monoxide oxidation

Effect of organic capping layers over monodisperse platinum nanoparticles upon activity for ethylene hydrogenation and carbon monoxide oxidation

Structure and Nature of the Active Sites in CoMo Hydrotreating Catalysts Conversion of Thiophene

Properties, environmental fate and biodegradation of carbazole

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