The hetero‐homogeneous pyrolysis of propane, in the presence or in the absence of dihydrogen, and the measurement of uptake coefficients of hydrogen atoms

Perrin, D. D.; Martin, René

doi:10.1002/(sici)1097-4601(2000)32:6<340::aid-kin2>3.0.co;2-#

Cited by 7 publications

(7 citation statements)

References 61 publications

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“…In the case of propane, two types of radicals, isopropyl and n-propyl were formed. Although the secondary carbon–hydrogen bond energy was about 10 kJ/mol lower than that of the primary carbon–hydrogen, these two radicals formed in approximately the same ratio . The carbon–hydrogen bond cleavage of the isopropyl radical led to the formation of propylene while the β-scission led to formation of ethylene.…”

Section: Effect Of Reaction Conditions On Product Yieldsmentioning

confidence: 95%

“…Although the secondary carbon−hydrogen bond energy was about 10 kJ/mol lower than that of the primary carbon−hydrogen, these two radicals formed in approximately the same ratio. 48 The carbon−hydrogen bond cleavage of the isopropyl radical led to the formation of propylene while the β-scission led to formation of ethylene. The absence of methane in significant amounts suggested that oxy-cracking (and not the thermal cracking) was the dominant cracking mechanism leading to the formation of ethylene and CO x .…”

Section: Effect Of Reaction Conditions On Product Yieldsmentioning

confidence: 99%

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Vanadium Pentoxide Catalyst over Carbon-Based Nanomaterials for the Oxidative Dehydrogenation of Propane

Fattahi

Kazemeini

Khorasheh

et al. 2013

Ind. Eng. Chem. Res.

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A series of V 2 O 5 catalysts supported on multiwall carbon nanotube (MWCNT), single wall carbon nanotube (SWCNT), and graphene were synthesized by hydrothermal and reflux methods for oxidative dehydrogenation of propane (ODHP) to propylene. The catalysts were characterized by techniques including the BET surface area measurements, XRD, FTIR, H 2 -TPR, NH 3 -TPD, FESEM, and UV−vis diffuse reflectance spectroscopy. The performance of the catalysts and the supports were subsequently examined in a fixed bed reactor. The main products were propylene, ethylene and CO x . The vanadium catalyst supported on graphene with C/V molar ratio of 1:1 synthesized through the hydrothermal method had the best performance under the reactor test conditions of 450 °C, feed C 3 H 8 /air molar ratio of 0.6, and the total feed flow rate of 90 mL/min resulting in average values of 53.6% and 50.7% for propylene selectivity and propane conversion, respectively. This catalyst was further employed in a series of experiments to study the effects of operating parameters including the reaction temperature, propane to air ratio, and the total feed flow rate on conversions and product selectivities using an experimental design method utilizing the response surface methodology (RSM) with central composite design at three levels. The resulting quadratic equations properly correlated the obtained experimental data. Optimum conditions for maximizing propane conversion and propylene selectivity as well as minimizing the CO x selectivity were determined at the temperature of 500 °C, C 3 H 8 /air molar ratio of 0.28, and total flow rate of 60 mL/min. Ultimately, results under optimum conditions revealed satisfactory agreement between the experimental and predicted data.

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Section: Effect Of Reaction Conditions On Product Yieldsmentioning

confidence: 95%

Section: Effect Of Reaction Conditions On Product Yieldsmentioning

confidence: 99%

Vanadium Pentoxide Catalyst over Carbon-Based Nanomaterials for the Oxidative Dehydrogenation of Propane

Fattahi

Kazemeini

Khorasheh

et al. 2013

Ind. Eng. Chem. Res.

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“…Although many papers have studied propane cracking for one reason or another, , most are at higher temperature or lower pressure than for this application, and the most relevant study was at significantly higher temperatures. Given that the activation energy at elevated pressure may be higher than near atmospheric pressure, the available literature was insufficient for a reliable extrapolation to our conditions.…”

Section: Introductionmentioning

confidence: 99%

Kinetics of Propane Cracking Related to Its Use as a Heat-Transfer Fluid

Burnham¹,

Turk²,

McConaghy

et al. 2015

Energy Fuels

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The kinetics of propane cracking at high pressure were measured to evaluate its suitability as a heat-transfer fluid, in either a closed loop or directly injected into the formation, to retort oil shale in situ. Rate constants were measured in batch reactors at isothermal temperatures from 450 to 540°C and at constant heating rates of 1.5 and 3.6°C/min. Rate constants were also measured in a flow loop for isothermal temperatures ranging from 440 to 473°C. The lowest temperatures in the batch autoclave experiments showed evidence of autocatalytic kinetic behavior, but the higher temperature batch experiments and the flow loop were more nearly first-order. The overall rate constants were consistent with an extrapolation of results from higher temperature measurements. Product selectivity changed as a function of conversion, with low conversion products rich in C 4+ products and high conversion products predominantly methane. A combination of the propane kinetics with simple heat balance calculations shows that more than enough propane is supplied by the retorting operation to balance the consumption by cracking, making the use of propane for the heat-transfer fluid self-sustaining. ■ INTRODUCTIONA variety of true in situ oil shale retorting processes are being researched, 1−3 including various methods of delivering or generating the heat of retorting down into the oil-shale formation. Heat delivery methods include resistive electrical circuits, closed-loop hot pipes immersed in a boiling oil pool, and hot gas injected into heating wells. The initial permeability of the oil shale is usually negligible; therefore, a base case is to heat the formation by thermal conduction from the heater wells. However, 20−30% porosity and associated permeability is generated by kerogen removal, which might provide for significant convective heat transfer into the formation.The advent of super-insulation materials 4 makes generation of heat on the surface and injection underground more attractive than previously. To carry that heat to the retort in either a closed loop or direct injection, a heat-transfer fluid with both a high heat capacity and high thermal stability is desired. One proposal by EGL Resources 5 initially used steam because of its high latent heat and then switched to an industrial heattransfer fluid, such as Therminol VP-1 (Solutia-Eastman) or Dowtherm A (Dow Chemical), to raise the formation to a pyrolysis temperature of 350°C. Given that the driving force for heat deposition is proportional to how much hotter than 350°C the heat transfer fluid is, it is highly advantageous to use a heat-transfer fluid above 450°C, which is above the working temperature of all currently available industrial heating fluids (with the exception of molten salts).Although steam, N 2 , and CO 2 are very stable, they have relatively low sensible molar heat capacities compared to light hydrocarbons. Ethane is about 50% greater; propane is twice as large; and butane is nearly 3 times higher. However, a preliminary screening indicated that th...

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“…One way to achieve this is by adding to propane certain gaseous species that can readily generate extra radicals. The introduction of H 2 11–13, H 2 O 14, 15, and H 2 S 16–18 has been shown to accelerate the overall rate of propane decomposition. However, the effects of these added gases on product selectivities appear to differ widely.…”

Section: Introductionmentioning

confidence: 99%

“…However, the effects of these added gases on product selectivities appear to differ widely. For example, the addition of H 2 increased the yields for CH 4 , C 2 H 4 , and C 2 H 6 , and decreased the yield of C 3 H 6 11–13. Increasing the steam concentration in “steam cracking” could significantly increase C 2 H 4 formation rate and decrease the formation rates of CH 4 , C 2 H 6 , and C 3 H 6 14, 15.…”

Section: Introductionmentioning

confidence: 99%

Two novel applications of ion exchange fibers: Arsenic removal and chemical‐free softening of hard water

2006

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Separation processes using ion exchange materials are ubiquitous regarding the selective removal of contaminants of environmental concern. Recently, highly regulated contaminants, such as arsenic, have gained notoriety on account of carcinogenic effects and subsequent promulgation of new drinking water standards by the United States Environmental Protection Agency. Other nonregulated compounds such as hardness (e.g., Ca2+, Mg2+), pose a particular concern to avoid scaling in heat‐transfer equipment, foulingz in membranes, and high consumption of detergents and sequestering chemicals in cooling and wash water. In general, ion exchange processes used to remove hardness generate concentrated brine or mineral acid as a waste regenerant stream. Residuals management and long‐term sustainability issues will continue to be major concerns with these processes. The subject paper reports and discusses the results and attributes of two new separation processes using ion exchange fibers (IX‐fibers). The first process involves the selective removal of arsenic using hybridized IX‐fibers that contain dispersed hydrated ferric oxide (HFO) nanoparticles. Anion‐exchanger‐supported HFO particles offered a high arsenic removal capacity; less than 10% of influent arsenic broke through after 30,000 bed volumes. Hybrid fibers were also amenable to efficient regeneration with 2% NaOH and 2% NaCl and capable of simultaneous removal of both arsenic(V) and arsenic(III). The second process involves the environmentally benign removal of hardness. Most importantly, this process uses harvested snowmelt (or rainwater) sparged with carbon dioxide as the regenerant. Consequently, the spent regenerant does not contain a high concentration of aggressive chemicals such as sodium chloride or acid like traditional ion‐exchange processes nor does the process produce voluminous sludges as does lime softening. The bulk of carbon dioxide consumed during regeneration remains sequestered in the aqueous phase as alkalinity. For both treatment strategies, IX‐fibers form the heart of the process. They are essentially thin cylindrical polymeric strands 10–20 μm in diameter with functional groups residing near to the fiber surface. Low intraparticle diffusional resistance is the underlying reason why calcium loaded weak acid IX‐fibers are amenable to efficient regeneration using either snowmelt or rainwater sparged with carbon dioxide. Additionally, for hybrid IX‐fibers, enhanced adsorption kinetics may offer the possibility for certain point of use applications, which are unavailable to their resin counterparts. © 2006 American Institute of Chemical Engineers Environ Prog, 2006

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The hetero‐homogeneous pyrolysis of propane, in the presence or in the absence of dihydrogen, and the measurement of uptake coefficients of hydrogen atoms

Cited by 7 publications

References 61 publications

Vanadium Pentoxide Catalyst over Carbon-Based Nanomaterials for the Oxidative Dehydrogenation of Propane

Vanadium Pentoxide Catalyst over Carbon-Based Nanomaterials for the Oxidative Dehydrogenation of Propane

Kinetics of Propane Cracking Related to Its Use as a Heat-Transfer Fluid

Two novel applications of ion exchange fibers: Arsenic removal and chemical‐free softening of hard water

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