Propane Ammoxidation Research Articles

Factors affecting selectivity and activity of oxidation catalysts

Robert K. Grasselli Chemistry Department, Case Western Reserve University Cleveland, Ohio 44106, U.S.A. Received May 15, 1987 Selective catalytic oxidation of olefins has been successfully practiced on a commercial scale for almost thirty years {1). Processes which have been commercialized are the oxydehydrogenation of n-butenes to butadiene (a two electron oxidation), the oxidation of propylene to acrolein (a four electron oxidation) and its subsequent oxidation to acrylic acid (a two electron oxidation), and the ammoxidation of propylene to acrylonitrile (a six electron oxidation) (2). More recently the fourteen electron oxidation of n-butane to maleic anhydride has been achieved catalytically and will be commercialized in the near future (3). Fundamental studies pertaining to these processes have shed a considerable light on the mechanistic intricacies of catalysts effective in selective oxidation (4).

Functionalization of paraffinic hydrocarbons by heterogeneous oxidation. I. Control of selectivity in n-butane conversion to maleic anhydride

The selectivity in maleic anhydride formation from n-butane in different reagent conditions and on (VO) 2P 2O 7 catalysts with different rates of oxidation of vanadium was studied and compared with the results obtained (I) in the oxidation of propane and ethane, (II) in the ammoxidation of propane and (III) in the oxidation of n-butane on different vanadium-based catalysts (vanadium-titanium oxide and vanadium-antimony oxide). The results indicate that in the selective oxidation of alkanes not only the first step of activation is important, but also of particular importance is the stability in the reaction conditions of the products formed, which depends either on the oxidizing power of the surface or on the stability of the product formed as regards consecutive oxidation. The other vanadium-based catalysts tested are also able to activate the paraffin, but not to control the oxidation, and only carbon oxides are formed. Similarly, propane and ethane are also activated, but due to the reactivity of the products in consecutive oxidation, only carbon oxides are obtained. On the contrary in the ammoxidation of propane, due to the higher stability of the product, acrylonitrile is formed at the higher temperatures or propylene at the lower temperatures. However ammonia is a strong inhibitor of the activity of the catalyst sites to which the ability of these catalysts in the activation of the paraffinic hydrocarbon was attributed.

MODELING OF THE TRANSIENT AND STEADY STATE OPERATION OF A FLUIDIZED BED REACTOR WITH ADAPTIVE CONTROL OF TEMPERATURE

This paper concerns modeling of the transient and the steady state operation of a fluidized bed reactor for the catalytic ammoxidation of propylene to acrylonitrile. To maintain constant the temperature of the reaction in order to facilitate the phenomenological study as well as to avoid risks of destruction of the catalyst, a self tuning P.I.D. controller has been used. The controller derived from a discrete P.I.D. regulator is based on pole assignment. It uses a recursive parameter estimator based on the least square method. The reactor has been interfaced with an Apple II micro-computer. The results obtained illustrates the inherent capability of self adaptive control to adapt the change of the environment where conventional control fails Modeling of the reactor is based on the Kato and Wen bubble assemblage model corrected by including the wake of the bubbles with their clouds, as proposed hy Stergiou. This modified model gives good predictions of the operation of the reactor for steady as well as tra...

ChemInform Abstract: Identification of Active Oxide Ions in a Bismuth Molybdate Selective Oxidation Catalyst.

Direct structural identification of catalytically active oxide ions for selective olefin oxidation has been achieved using in situ Raman spectroscopy. Spectroscopic examination of Bi2MoO6 reduced with select probe molecules such as but-1-ene, propene, methanol and ammonia, when reoxidized with oxygen-18, establishes the existence of the multifunctional nature of catalyst active site for propene oxidation and ammoxidation, wherein α-H abstraction occurs by oxide ions bridging bismuth and molybdenum atoms (Bi—O—Mo), and oxygen or NH insertion into the π-allylic intermediate occurs at centres associated with molybdenum. Sites for O2 chemisorption, reduction and dissociation are likely to be associated with the directed lone pairs of electrons of the Bi—O—Bi species in the structure. Pulse kinetic experiments reveal that diffusion of the oxide ions through the bulk of the catalyst is the rate-limiting step in catalyst reoxidation. This process is rapid when an oxide ion of only one functional type, i.e.α-H abstraction or oxygen insertion, is removed. The process becomes less facile when oxide ions associated with both α-H abstraction and oxygen insertion are removed from the catalyst. The relative rates reflect the extent of active-site reconstruction achieved by diffusion of oxide ions from the bulk to the surface of the catalyst.

Influence of initial reactants in propene ammoxidation on the isomerization activity of complex Mo-containing oxide catalysts

Surface reduction of complex Mo-containing oxide catalysts by the initial reactant in propene ammoxidation increases its activity in isomerization of butene-1 to butene-2. Isomerization and conversion of ammonia, propene and their mixtures are suggested to take place on the same active centers of the catalyst.

Transient response study of the participation of adsorbed forms of ammonia in propene ammoxidation

On the basis of transient response studies, it is suggested that ammonia on the surface of a Mo−Si−Bi−P oxide catalyst forms a compound that is stable at the reaction temperature and whose reaction with propene yields acrylonitrile.

Phase cooperation in oxidation catalysis. Structural studies of the iron antimonate–antimony oxide system

The compositions FeSb2O6 and FeSb5O12 of the two-phase FeSbO4–α-Sb2O4 system, an active and selective catalyst for the oxidation and ammoxidation of propylene, have been structurally characterized by Rietveld analysis of powder neutron-diffraction data. Results of the analysis indicate that the presence of Sb2O4 has no effect on the bulk structural parameters of FeSbO4. Specifically (a) the unit cell of FeSbO4 does not depend upon the presence of Sb2O4 or calcination temperature, (b) antimony atoms are not found in the intersticies of the coexisting iron antimonate and (c) the apparent Sb/Fe ratio is 1 in iron antimonate. Additionally, the Sb/Fe occupancy in the rutile FeSbO4 structure is random as no supercell reflections were observed. Results of scanning electron microscope and X-ray photoelectron spectroscopy experiments have been interpreted to show that Sb enrichment occurs on coprepared samples of the two-phase mixture. Based on this evidence and the lack of alteration of the bulk structures of both phases it is suggested that surface alteration in this two-phase system is the key to enhanced selective catalytic oxidation activity.

Homogeneous models for propylene ammoxidation. 1. Tungsten(VI) imido complexes as models for the active sites

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTHomogeneous models for propylene ammoxidation. 1. Tungsten(VI) imido complexes as models for the active sitesDominic M. T. Chan, William C. Fultz, William A. Nugent, D. Christopher Roe, and Thomas H. TulipCite this: J. Am. Chem. Soc. 1985, 107, 1, 251–253Publication Date (Print):January 1, 1985Publication History Published online1 May 2002Published inissue 1 January 1985https://doi.org/10.1021/ja00287a046RIGHTS & PERMISSIONSArticle Views254Altmetric-Citations68LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (361 KB) Get e-AlertsSupporting Info (1)»Supporting Information Supporting Information Get e-Alerts

Pyridines by propylene ammoxidation: IV: Kinetic study

The study was performed at 330–390°C and atmospheric pressure on a Te-oxide/ silica-alumina-based catalyst by means of a continuous, fixed bed microreactor, operated by the integral reactor technique. The aim was to collect some general kinetic information, useful in planning a possible final kinetic study on a pilot plant. Kinetic parameters have been optimized by integration-non linear regression. The stoichiometry of the main reaction was written on the basis of the mechanism evidenced in previous work. Owing to the very complex nature of the reaction, involving also the formation of undetectable heavy byproducts (H), only three simplified models were considered. The best results were obtained by means of a six-parameters model, in which two parallel paths for the formation of H are provided.

A discrimination between some fluidized bed reactor models for ammoxidation of propylene to acrylonitrile

The study consists in making a discrimination between four fluidized bed reactor models: Davidson and Harrison, Partridge and Rowe, Kunii and Levenspiel, Kato and Wen models. Their predictions are compared with data obtained by carrying out experiments on the catalytic ammoxidation of propylene to acrylonitrile in a 165 mm dia. reactor. These experiments were designed to test the models as selectively as possible. On statistical ground, none of them is acceptable as representing the behaviour of the reactor over the whole range of operating conditions. However, the models of Partridge and Rowe, Kunii and Levenspiel and Kato and Wen lead to rather good predictions on limited ranges of gas flow rate or mass of catalyst. Among them, the bubble assemblage model of Kato and Wen provides the best overall predictions if it is slightly modified by including the wakes of the bubbles with their clouds or by reducing the bubble formation diameter, for instance.

Some remarks on the mechanism of ammoxidation of propane in a fluidized bed

Using the measurements of product accumulation in dependence on increasing propane conversion, it has been shown that in the ammoxidation of propane the desired product acrylonitrile is formed via intermediate propene.

An investigation of the role of bismuth and defect cation vacancies in selective oxidation and ammoxidation catalysis

The roles of bismuth and cation vacancy defects in the selective ammoxidation of propylene to acrylonitrile were investigated. Based on kinetic and spectroscopic studies of several scheelite molybdate catalysts, it is concluded that bismuth, and not cation vacancies, is responsible for the formation of the allylic intermediate from propylene. Cation vacancies generate molybdenyl-type functionalities in the vicinity of the defects which are responsible for the insertion of oxygen or nitrogen into the allylic intermediate in the selective oxidation or ammoxidation of propylene, respectively.

Etude expérimentale de l'ammoxydation catalytique du propène dans un réacteur différentiel

The kinetics of ammoxidation of propene has been studied over an industrial Sn/Sb oxides catalyst in a differential reactor at 490 °C. Factorial design of experiments leads to reliable rate equations over the range of partial pressures encountered in a fluidized bed reactor. The rate of disappearance of propene may be represented by the equation r 1 = 1.497 × 10 −7 P C 3H 6 0.48 P O 2 0.48 P NH 3 0.19 and the rate of formation of acrylonitrile by r 4 = 1.287 × 10 −7 P C 3H 6 0.43 P O 2 0.52 P NH 3 0.47 A best fit is obtained by the addition of some empirical pressure interaction terms. Catalytic activity is about the same as for other Sn/Sb oxides catalysts and maximum selectivity at 490 °C is at least 82%.

Relationship between solid state structure and catalytic activity of rare earth and bismuth-containing molybdate ammoxidation catalysts

The formation of solid solutions in rare earth and bismuth-containing molybdate catalysts plays a key role in the selective ammoxidation of propylene to acrylonitrile. Solid state structural studies of the Bi 2 − x Ce x (MoO 4) 3 system reveal that bismuth dissolves readily in the Ce 2(MoO 4) 3 lattice which crystallizes in the low-temperature La 2(MoO 4) 3 structure, yielding a single-phase material when x ≥ 1. The solubility of cerium in the Bi 2(MoO 4) 3 structure is less extensive, with maximum solubility occurring at x − 0.2. Structural substitution of bismuth or cerium by rare earth cations such as La, Pr, Nd, and Y results in lattice parameter changes which indicate that bismuth and cerium cations randomly occupy equivalent positions in BiCe-molybdate solid solutions. Catalytic activity maxima correlate well with phase compositions and occur in the two single phase regions, where there is maximum solubility of bismuth in the cerium molybdate phase and maximum solubility of cerium in the bismuth molybdate phase. A third catalytic maximum is observed in the binary phase region of the two saturated solid solutions and coincides with equal solubility of Ce in the Bi-molybdate phase and Bi in the Ce-molybdate phase. At these three optimum catalyst compositions, maximum interactions exist between the three key catalytic components: Bi (α-H-abstracting element), Ce (oxygen and electron transfer element), and Mo (olefin chemisorption and nitrogen insertion element).

ChemInform Abstract: PYRIDINES BY PROPYLENE AMMOXIDATION. III. CATALYST OPTIMAL COMPOSITION AND PROCESS MAIN PARAMETERS

Chemischer InformationsdienstVolume 13, Issue 37 Preparative Organic Chemistry ChemInform Abstract: PYRIDINES BY PROPYLENE AMMOXIDATION. III. CATALYST OPTIMAL COMPOSITION AND PROCESS MAIN PARAMETERS L. FORNI, L. FORNISearch for more papers by this authorG. GIANETTI, G. GIANETTISearch for more papers by this author L. FORNI, L. FORNISearch for more papers by this authorG. GIANETTI, G. GIANETTISearch for more papers by this author First published: September 14, 1982 https://doi.org/10.1002/chin.198237102AboutPDF ToolsRequest permissionExport citationAdd to favoritesTrack citation ShareShare Give accessShare full text accessShare full-text accessPlease review our Terms and Conditions of Use and check box below to share full-text version of article.I have read and accept the Wiley Online Library Terms and Conditions of UseShareable LinkUse the link below to share a full-text version of this article with your friends and colleagues. Learn more.Copy URL Share a linkShare onFacebookTwitterLinked InRedditWechat No abstract is available for this article. Volume13, Issue37September 14, 1982 RelatedInformation

Pyridines by propylene ammoxidation: III. Catalyst optimal composition and process main parameters

The influence of catalyst composition on reaction selectivity for propylene ammoxidation was studied and some basic information about the main practical aspects of the process was collected. Si-Al-Te-Sb-O has been used as catalyst. The catalyst performed satisfactorily within the temperature range 310–390 °C and proved capable of withstanding quite rigorous operating conditions and abrupt changes in feed composition. The partial orders of reaction and at least the order of magnitude of the main kinetic parameters were also determined.

Structure and activity of tellurium-cerium oxide acrylonitrile catalysts

Ammoxidation of propylene to acrylonitrile (ACN) was investigated over various silica-supported (Te,Ce)O catalysts at 360 and 440 °C. The binary oxide system used consists of a single nonstoichiometric fluorite-type phase α-(Ce,Te)O 2 up to about 80 mole% TeO 2 and a tellurium-saturated solid solution β-(Ce,Te)O 2 together with α-TeO 2 at higher tellurium concentrations. The ACN yield varies almost linearly with the tellurium content of (Ce,Te)O 2. The β-(Ce,Te)O 2 phase is the most active component of the system (propylene conversion and ACN selectivity at 440 °C of 76.7 and 74%, respectively) and is slightly more selective to ACN than α-TeO 2. Tellurium reduces the overoxidation properties of cerium and selective oxidation occurs through Te(IV)-bonded oxygen.

ChemInform Abstract: Selective Oxidation and Ammoxidation of Propylene by Heterogeneous Catalysis (27 Literaturzitate).

ChemInform Abstract: Selective Oxidation and Ammoxidation of Propylene by Heterogeneous Catalysis (27 Literaturzitate).

Influence of the silica support of iron-antimony oxides on the oxidation and ammoxidation of propene

The conversion of propene and the yield of acrylonitrile decrease during ammoxidation with increasing content of silica support of iron-antimony oxides. In constrast to that, during oxidation, the conversion of propene and the yield of acrolein increase with increasing portion of silica in the catalysts. These results show that the appearance of acrylonitrile is not preceded by the formation of acrolein.

Electron microscopy of industrial oxidation catalysts

Abstract A combination of in situ high-voltage electron microscopy (HVEM), X-ray/ electron diffraction methods, X-ray and electron probe microanalysis as well as high-resolution phase contrast lattice imaging (<2 AS resolution) microscopy techniques has been used to investigate the reaction properties of an industrial tellurium-molybdenum oxide catalyst system used, for example, in the ammoxidation of propylene to produce organic chemicals such as acrylonitrile, acrolein and other hydrocarbon conversion reactions. In situ electron microscopy experiments conducted on the catalysts in reducing/oxidizing gaseous environments with pressures comparable to those used in the commercial reactions have revealed degradation products which have been analysed by high-resolution microscopy. In this industrial system at typical catalyst operating temperatures no evidence for crystallographic shear planes has been obtained and the implications concerning the role of such extended defects in industrial catalytic reaction...