The contribution of homogeneous and non-oxidative side reactions in the performance of vanadyl pyrophosphate, catalyst for the oxidation of n-butane to maleic anhydride, under hydrocarbon-rich conditions

Ballarini, Nicola; Cavani, Fabrizio; Cortelli, Carlotta; Gasparini, F.; Mignani, Adriana; Pierelli, Francesca; Trifirò, Ferruccio; Fumagalli, Carlo; Mazzoni, G.

doi:10.1016/j.cattod.2004.09.030

Cited by 13 publications

(11 citation statements)

References 22 publications

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“…A detailed investigation of the reaction products obtained with different gas-phase compositions evidenced the possible formation of heavy by-products when the n-butane concentration in feed is higher than 5-6% [118]. It was found that the availability of gasphase oxygen affects the nature of the by-products obtained.…”

Section: Reactivity Under N-butane-rich Conditions and The Role Of Tmentioning

confidence: 97%

VPO catalyst for n-butane oxidation to maleic anhydride: A goal achieved, or a still open challenge?

et al. 2006

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A Partner of Concorde CA and of Idecat NoE, 6FP of the EU) b Lonza SpA, via E. Fermi 51, 24020 Scanzorosciate (BG), ItalyThis review describes recent findings in the oxidation of n-butane to maleic anhydride. The process is commercial since the 80's, but yet the yield is far from being optimised. Therefore, it represents an emblematic example of how several scientific disciplines, from solid-state science to reactor technology, can contribute to the improvement of the process performance.KEY WORDS: Vanadyl pyrophosphate; n-butane; selective oxidation; maleic anhydride 1. The oxidation of n-butane catalysed by VPO: How to improve process performance?The activation of light alkanes by high-temperature contact with a redox catalyst represents one way to transform these hydrocarbons to valuable chemicals (a few reviews and books dealing with this topic, published after 1998, are refs [1-18]). The most successful example is the oxidation of n-butane to maleic anhydride (MA), catalysed by a V/P/O-based catalyst (VPO), which starting from the 80's has been replacing in part the commercial synthesis from benzene. This reaction, and the unique chemical-physical properties of the vanadyl pyrophosphate (VO) 2 P 2 O 7 (VPP), the active and selective phase for this reaction, are amongst the most studied topics in catalysis during the latest decades, initially with the aim of understanding which catalyst peculiarities make this complex transformation possible, and later on with the aim of improving the process performance.MA finds its major use in the production of unsaturated polyesters and of butanediol. The yearly world consumption exceeds 1.3 · 10 6 metric tons [19]. Approximately 70% is produced by n-butane oxidation, the remaining still being obtained from benzene. There are several reactor technologies available, including fixed-bed (Scientific Design, Huntsman, BASF, Pantochim), fluidised-bed (Lonza, BP, Mitsubishi), and transported-bed (DuPont). Best process performances reported in patent literature range from 53 to 65% molar yield to MA [20][21][22][23][24][25], with a conversion of the hydrocarbon not higher than 85-86%. An excellent result of more than 70% yield is reported [26], which however refers to a recycle process. In lab reactors best yields reported are lower than 50%.The best performance for a fixed-bed reactor does not exceed 65% per-pass yield, while that in a fluidised-bed is typically somewhat lower; in fact, back-mixing phenomena are responsible for the consecutive combustion of MA. Moreover, with fluidised-bed operation n-butane-richer conditions can be used (up to 5 molar % in feed); under the latter conditions, a worsening of selectivity is expected, which however is compensated by a considerable improvement in MA productivity. In the fluidised-bed process developed by Lonza and Lummus (shown in figure 1), the loss of selectivity is also compensated by the higher amount of high-pressure steam produced, due to the more efficient removal of the reaction heat and to the more CO x produced.The maximu...

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Section: Reactivity Under N-butane-rich Conditions and The Role Of Tmentioning

confidence: 97%

VPO catalyst for n-butane oxidation to maleic anhydride: A goal achieved, or a still open challenge?

et al. 2006

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“…[71,72] Under thesec ircumstances, the over-reduction of the Vs ites leads to the prevailing occurrence of bimolecular reactions, such as the cycloaddition of MA and butadiene, with am inor contribution of olefin oxidation to produce more MA. In the case of n-butane oxidation, the formationo fP Ab ecomes important only under the conditions of surface saturation as ar esult of the coverage of active sites by olefinic intermediates, an event that only occurs under alkane-rich feed conditions with the VPPc atalyst.…”

Section: Resultsmentioning

confidence: 99%

“…In the case of n-butane oxidation, the formationo fP Ab ecomes important only under the conditions of surface saturation as ar esult of the coverage of active sites by olefinic intermediates, an event that only occurs under alkane-rich feed conditions with the VPPc atalyst. [71,72] Under thesec ircumstances, the over-reduction of the Vs ites leads to the prevailing occurrence of bimolecular reactions, such as the cycloaddition of MA and butadiene, with am inor contribution of olefin oxidation to produce more MA. However,i ti sw orth noting that, in the case of n-pentane oxidationt oM Aa nd PA,t he mechanism proposed did not involve any Diels-Alder reaction between pentadiene andM Ab ut rather the oxidation of dialkylaromatics, which are formed by olefin dimerisation and oxidative dehydrocyclisation.…”

Section: Resultsmentioning

confidence: 99%

A New Process for Maleic Anhydride Synthesis from a Renewable Building Block: The Gas‐Phase Oxidehydration of Bio‐1‐butanol

et al. 2015

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We investigated the synthesis of maleic anhydride by oxidehydration of a bio-alcohol, 1-butanol, as a possible alternative to the classical process of n-butane oxidation. A vanadyl pyrophosphate catalyst was used to explore the one-pot reaction, which involved two sequential steps: 1) 1-butanol dehydration to 1-butene, catalysed by acid sites, and 2) the oxidation of butenes to maleic anhydride, catalysed by redox sites. A non-negligible amount of phthalic anhydride was also formed. The effect of different experimental parameters was investigated with chemically sourced 1-butanol, and the results were then confirmed by using genuinely bio-sourced 1-butanol. In the case of bio-1-butanol, however, the purity of the product remarkably affected the yield of maleic anhydride. It was found that the reaction mechanism includes the oxidation of butenes to crotonaldehyde and the oxidation of the latter to either furan or maleic acid, both of which are transformed to produce maleic anhydride.

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“…Two possibilities exist, to explain the hightemperature formation of formaldehyde: either the oxidative degradation of MA brings to the formation of formaldehyde and of carbon oxides, or homogeneous reactions are responsible for the undesired transformation of n-butane to these by-products. In a recent work we reported about the role of homogeneous reactions in the oxidation of n-butane catalyzed by undiluted VPP [33]; it was found that homogeneous reactions contribute to n-butane conversion only when inlet hydrocarbon concentrations higher than 3-4% are used. Therefore, it is likely that the first hypothesis is the correct one, and that the heterogeneous oxidative degradation of MA leads to the generation of formaldehyde and carbon oxides.…”

Section: The Reactivity In N-butane Oxidationmentioning

confidence: 97%

The dilution of vanadyl pyrophosphate, catalyst for n-butane oxidation to maleic anhydride, with aluminum phosphate: unexpected reactivity due to the contribution of the diluting agent

et al. 2006

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This paper describes the preparation, characterization and reactivity in n-butane oxidation of catalysts made of vanadyl pyrophosphate (VPP) diluted in aluminum phosphate. Catalysts were prepared by synthesizing at the same time the VPP precursor and AlPO 4 , in order to develop mixed systems, suitable for the conglomeration into fluidizable particles by spray-drying. Al phosphate was chosen due to its presumed chemical inertness towards the active phase and towards n-butane. No evidence was obtained for the formation of mixed V/Al phosphates; an homogeneous reciprocal dispersion of the two compounds developed. However, Al phosphate showed an unexpected activity in n-butane oxidation; specifically, in the temperature range comprised between 340 and 400°C, the hydrocarbon was converted to formaldehyde and carbon monoxide by radical-like reactions. The activity of Al phosphate became negligible above 400°C, in the temperature range where instead VPP was active in hydrocarbon oxidation and selective to maleic anhydride. Moreover, Al phosphate was also responsible for the consecutive oxidative degradation of maleic anhydride, at high temperature.

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The contribution of homogeneous and non-oxidative side reactions in the performance of vanadyl pyrophosphate, catalyst for the oxidation of n-butane to maleic anhydride, under hydrocarbon-rich conditions

Cited by 13 publications

References 22 publications

VPO catalyst for n-butane oxidation to maleic anhydride: A goal achieved, or a still open challenge?

VPO catalyst for n-butane oxidation to maleic anhydride: A goal achieved, or a still open challenge?

A New Process for Maleic Anhydride Synthesis from a Renewable Building Block: The Gas‐Phase Oxidehydration of Bio‐1‐butanol

The dilution of vanadyl pyrophosphate, catalyst for n-butane oxidation to maleic anhydride, with aluminum phosphate: unexpected reactivity due to the contribution of the diluting agent

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