Redox kinetics of VOPO4 with butane and oxygen using the TAP reactor system

Mills, Patrick L.; Randall, Harvey; McCracken, J.S.

doi:10.1016/s0009-2509(99)00008-1

Cited by 37 publications

(21 citation statements)

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“…Most of the studies agree that subsurface oxygen is several monolayers thick process is fast enough as compared to the butane oxidation step, whereas other studies 14,22 have reported that subsurface oxygen diffusion is relatively slow. The role of ''subsurface oxygen diffusion'' becomes crucial especially if the reactor is a short contact time reactor (such as some elements of a circulating fluidized bed loop), as butane oxidation could become limited by the extent of regeneration of the catalyst and the ability (or lack thereof) of the subsurface oxygen to contact the gas-phase oxygen at the catalyst surface.…”

Section: Kinetics Of N-butane Oxidationmentioning

confidence: 86%

“…Huang et al 22 further postulated that lattice oxygen is responsible only for the formation of MAN whereas butane oxidizes to CO x via participation of adsorbed oxygen. In contrast, Mills et al 14 and Lorences et al 24 proposed a mechanism in which only ''lattice oxygen'' is responsible for MAN formation as well as CO x formation.…”

Section: Kinetics Of N-butane Oxidationmentioning

confidence: 98%

“…As compared to other researchers, including relatively recent publications, 22,28 Mills et al 14 advocate the role of subsurface oxygen diffusion explicitly in their kinetic mechanism. Further, they show clear evidence of this mechanism through their kinetics work using a TAP (''Temporal Analysis of Products'') reactor, a millisecond microreactor setup wherein it is possible to temporally segregate oxygenrich and oxygen-lean environments.…”

Section: Kinetics Of N-butane Oxidationmentioning

confidence: 99%

“…Roy et al 12 proposed a phenomenological model for the partial oxidation of n-butane in a gas-solids riser reactor using steady state kinetics, 13 as well as unsteady state kinetics. 14 Roy et al 12 studied the effect of catalyst deactivation, n-butane feed concentration and solids backmixing, and in summary concluded that the highly backmixed solids phase and corresponding exposure to longer residence times for a fraction of the catalyst inventory results in reduced selectivity of the process to the desired product (MAN). In last two decades, a new ''quick'' reactor concept, the so called ''downer'' reactor 15,16 has been proposed to overcome the limitations of riser reactor.…”

Section: Introductionmentioning

confidence: 99%

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Modeling of partial oxidation in gas–solids downer reactors

2009

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Selective partial oxidations represent an important class of reactions in the process industry. Of particular interest is the partial oxidation of n-butane to maleic anhydride (MAN), which is arguably the largest commercialized alkane partial oxidation process. Partial oxidation of n-butane, which uses vanadium phosphorous oxide (VPO) as a heterogeneous catalyst, is believed to operate through a unique mechanism in which lattice oxygen oxidizes n-butane selectively to MAN. Past work has shown that performing partial oxidation reactions in gas-solids riser configuration is realizable and commercially viable, which has lead to commercialization of this technology in the last decade. Though the riser configuration allows optimal and independent control of the oxidation and reduction steps, the riser unit suffers from solid backmixing at walls, which in turn result into lower conversion, nonoptimal selectivity and diminished overall yield of desired product. In recent years, there has been growing interest in downers involving cocurrent downflow of both solids and gas phases, hence offering relatively uniform flow characteristics. In this contribution, we explore through modeling the implications of effecting partial oxidation reactions in a downer (gas-solids cocurrent downflow) compared to that in a conventional riser reactor (gas-solids cocurrent up flow) operated under equivalent operating conditions. Further, we explore the operational space of downers for these reactions, suggesting ways for improving the productivity of downer for partial oxidation applications. V

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Section: Kinetics Of N-butane Oxidationmentioning

confidence: 86%

Section: Kinetics Of N-butane Oxidationmentioning

confidence: 98%

Section: Kinetics Of N-butane Oxidationmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modeling of partial oxidation in gas–solids downer reactors

2009

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show abstract

“…Mills et al [3] using the TAP reactor investigated the details of the reduction kinetics of the vanadium-phosphorous catalyst by butane and its re-oxidation by oxygen. An interaction of the components of the reaction mixture with V/Ti-oxide catalysts was intensively studied for o-xylene oxidation [4][5][6] -important industrial reaction of phthalic anhydride production.…”

Section: Introductionmentioning

confidence: 99%