Studies of the hydrogen held by solidsIX. The hydroxyl groups of alumina and silica-alumina as sites for the isomerization of butene

Gerberich, H.R.; Hall, W

doi:10.1016/s0021-9517(66)80129-x

Cited by 48 publications

(4 citation statements)

References 12 publications

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“…Some researchers also suggested hydrogen addition−abstraction and "hydrogen switch" mechanisms in which double bond migration occurred through simultaneous addition of a hydrogen furnished by the silica-alumina catalyst and release of hydrogen from another carbon, yielding an isomer. 64,66 In this study, stereoisomers (E and Z configurations) of noctene were formed. At the experimental conditions used in the current study, the selectivity for Z isomers exceeded the selectivity for E isomers, as indicated by the peak areas in Table 9.…”

Section: Energy and Fuelsmentioning

confidence: 80%

“…The coordinatively unsaturated aluminum sites act as Lewis acid sites in a clay mineral and facilitate the 1,3 hydride shift of the allylic hydrogen. Some researchers also suggested hydrogen addition–abstraction and “hydrogen switch” mechanisms in which double bond migration occurred through simultaneous addition of a hydrogen furnished by the silica-alumina catalyst and release of hydrogen from another carbon, yielding an isomer. , …”

Section: Discussionmentioning

confidence: 99%

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Free Radical and Cationic Addition due to Clay Minerals Found in Bitumen Froth at 250 °C Probed with Use of α-Methylstyrene and 1-Octene

Turuga

Klerk

2022

Energy Fuels

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Following previous evidence that hydrothermal treatment of bitumen froth does not lead to bitumen upgrading at 250 °C and promotes viscosity increase, the current study explores the free radical and cationic reactivity of clay minerals found in bitumen froth in promoting heavier material formation through addition reactions. The current investigation employed α-methylstyrene (AMS) and 1-octene as probe molecules instead of bitumen froth, and their conversion at 250 °C in the presence of clay minerals kaolinite and illite was studied in batch reactors. Thermal conversion of AMS and 1-octene at 250 °C in the absence of minerals was observed to be low. In the presence of clay minerals, not only the conversion of AMS and 1-octene was increased but also reactions such as dimerization of AMS and alkylation of 1-octene and toluene (used as solvents) were mainly promoted, leading to heavier product formation. Double-bond isomerization of 1-octene and cumene formation from AMS was side reactions that were also promoted by the clay minerals. Suppression of mineral-related conversion by pyridine and selectivity to different reaction products that enabled differentiation between free radical and cationic reaction pathways indicated that the mineral-related conversion was predominantly cationic in nature. Using the reactions in the presence of minerals and pyridine as surrogates for alkaline bitumen froth, it was concluded that even under alkaline conditions, minerals could promote heavier material formation through cationic addition.

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Section: Energy and Fuelsmentioning

confidence: 80%

Section: Discussionmentioning

confidence: 99%

Free Radical and Cationic Addition due to Clay Minerals Found in Bitumen Froth at 250 °C Probed with Use of α-Methylstyrene and 1-Octene

Turuga

Klerk

2022

Energy Fuels

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“…A correlation was also found between the degree of olefin chemisorption and the degree of catalyst hydration, with maximum olefin chemisorption found at a water content of 1.3% . The effect of water on ASA activity has also been noted in increasing hydrogen exchange reactions, − double bond isomerization, ,, skeletal isomerization, and cracking. , A comparative study between ASA and ZSM-5 for the conversion of methanol to hydrocarbons indicated that the water formed during the reaction reduced the extent of coking on ASA and that the catalyst showed no noticeable change in activity on repeated regeneration . The possible effect of oxygenates on ASA is therefore not necessarily negative.…”

Section: Introductionmentioning

confidence: 94%

Effect of Oxygenates on the Oligomerization of Fischer−Tropsch Olefins over Amorphous Silica−Alumina

Klerk

2007

Energy Fuels

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The oligomerization of Fischer-Tropsch derived olefins over amorphous silica-alumina (ASA) has been investigated with feed materials containing 1-4% oxygenates to determine the effect of the oxygenates on catalyst performance and transportation fuel quality. The main differences between the oligomerization of oxygenate-containing and oxygenate-free olefinic feeds were: (a) higher deposition rate of carbonaceous material on the catalyst due to the carbonyls in the feed being converted to aromatic coke precursors; (b) shorter cycle length, although cycle lengths up to 8 months could be achieved with careful operation; and (c) formation of carboxylic acids from the carbonyls in the feed. Reaction over alumina and water washing were evaluated as feed pretreatment steps to reduce the oxygenate content in the feed, but neither were able to completely remove the carbonyls. All tests were done at pilot plant scale in the operating range 110-300 °C and 6 MPa.

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“…This is consistent with the feed composition being hydrogen lean; hydrogen is consumed in the hydrogenation reaction along the first 10 mm of the bed; further downstream the isomerisation reaction to 2-octenes dominate. It is believed that the isomerisation does not consume molecular hydrogen H 2 (Turkevich and Smith, 1948), and that any hydrogen required by the isomerisation reaction is not necessarily from molecular H 2 but may be supplied by the hydroxyl groups on the support surface (Gerberich and Hall, 1966;Wells and Wilson, 1967) and the hydrogen in hydrocarbon molecules (Thomson and Webb, 1976). The composition of 1-octene generally remains stable or slightly decreases along the catalyst bed.…”

Section: Reaction Experimentsmentioning

confidence: 99%

Operando determination of the liquid-solid mass transfer coefficient during 1-octene hydrogenation

Zheng

Russo-Abegao

Sederman

et al. 2017

Chemical Engineering Science

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Spatially-resolved and unresolved magnetic resonance measurements are used in combination with a partial least squares regression (PLSR) method to measure chemical composition within catalyst pellets during the 1-octene hydrogenation reaction occurring in a fixed bed of 0.3 wt% Pd/Al 2 O 3 catalyst pellets. The PLSR method is used to discriminate between chemical species within and external to the void space of the catalyst pellets. The spatiallyresolved data show that the hydrogenation and isomerisation reactions are dominant in the upper and lower region of the reactor, respectively. The local intra-pellet compositions also show product accumulation inside catalyst pellets consistent with reaction occurring under conditions of mass transfer limitation. An average measure of the intra-pellet composition within the whole bed was then used to estimate the liquid-solid mass transfer coefficient during the course of the reaction. The values of LS obtained from the NMR measurements were in the range 0.15 × 10-5 m s-1 < LS < 0.25 × 10-5 m s-1 , for reactor operating conditions characterised by gas and liquid Reynolds numbers 0.2 < L < 0.6 and 0.1< G <0.2; these values are shown to be consistent with those predicted by existing literature correlations. Closest agreement was found with values predicted from dissolution experiments performed under similar hydrodynamic conditions in trickle flow. In addition to introducing a method for the direct measurement of LS , the data presented also confirm that estimates of LS are more accurate when performed in an environment in which the hydrodynamics and fluidsolid contacting conditions are representative of the system of interest.

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Studies of the hydrogen held by solidsIX. The hydroxyl groups of alumina and silica-alumina as sites for the isomerization of butene

Cited by 48 publications

References 12 publications

Free Radical and Cationic Addition due to Clay Minerals Found in Bitumen Froth at 250 °C Probed with Use of α-Methylstyrene and 1-Octene

Free Radical and Cationic Addition due to Clay Minerals Found in Bitumen Froth at 250 °C Probed with Use of α-Methylstyrene and 1-Octene

Effect of Oxygenates on the Oligomerization of Fischer−Tropsch Olefins over Amorphous Silica−Alumina

Operando determination of the liquid-solid mass transfer coefficient during 1-octene hydrogenation

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