Maleic Anhydride Yield Research Articles

Effect of Ⅲ B metals (Sc, Y, La and Ce) on active components regulation of VPO catalyst in n-butane selective oxidation

Vanadium phosphorus oxide (VPO) catalyst has been modified by the Ⅲ B elements (Sc, Y, La, Ce) have been prepared. Those catalysts were tested in n-butane selective oxidation, and it was shown that Y-VPO catalyst has the highest maleic anhydride (MA) yield among the studied catalysts. The VPO catalyst was characterized by a series of techniques. As evidenced by property characterization in conjunction with catalytic performance, we found that the presence of rare earth metals alters the phase composition of VPO catalyst. And then, the acidity of VPO catalyst was adjusted. Finally, the change of acidity could impact the n-butane activation process, which affected the n-butane conversion. Moreover, the rare earth metals also modulated the ratio of lattice oxygen and surface oxygen and then the MA selectivity.

Support vector machine-based modeling of grafting hyperbranched polyethylene glycol on polyethersulfone ultrafiltration membrane for separation of oil–water emulsion

In present study, a new method based on the support vector machine (SVM) approach was employed to calculate the oil–water permeation flux and grafting yield of maleic anhydride and hyperbranched polyethylene glycol (PEG) on the polyethersulfone (PES) membrane surface. A set of 7 input/output experimental data was applied for training and testing the results of the model. The results of the developed SVM model showed good compliance with the experimental data, as the value of correlation index for the developed model is 0.96, 0.95 and 0.98 for the maleic anhydride and hyperbranched PEG grafting and oil–water permeation flux, respectively. The model was also validated against the kinetic reaction of benzophenone formation on the PES membrane which derives from combination of benzophenone formation reactions and the Lambert–Beer law. Also, to validate the SVM results, the oil–water permeation flux and antifouling characteristics of the modified and neat membranes were investigated, and based on the results, the SVM can be considered as a strong modeling approach in membrane process technologies.

Process design and techno-economic analysis of gas and aqueous phase maleic anhydride production from biomass-derived furfural

Maleic anhydride is used worldwide for a wide range of applications: from the manufacture of resins to lubricant additives or agricultural chemicals. The current production processes use benzene or butane as raw materials. This work shows the conceptual design of two novel processes using furfural as raw material: (i) aqueous phase oxidation with H2O2 and (ii) gas phase oxidation with O2. The aqueous process uses a cheaper furfural feedstock, but the purification train is complicated due to the vast amount of water and the presence of byproducts. Results from the economic assessment show that the aqueous process is far from being viable with up-to-day technology due to the high H2O2 cost and the low catalyst activity. In the gas phase process, the high reaction temperatures (i.e., 573 K) make necessary energy integration. The achieved minimum selling price of the maleic anhydride is around 1900 $/t, which is in the same range as its current commercial price. Sensitivity analyses showed that the maleic anhydride yield is the key parameter affecting the final cost. Technology developments in catalysis that improve the maleic anhydride yield to values above 80%, together with lower furfural prices will lead to significant cost reductions.

Simulation of commercial fixed-bed reactor for maleic anhydride synthesis: application of different kinetic models and industrial process data

In this study, we have developed a relatively simple mathematical model capable of both simulating the synthesis of maleic anhydride from n-butane in industrial fixed-bed reactor and determining the influences of inlet process parameters on reactor performance. Ten kinetic models were used, and each of them was used in combination with a simplified reactor model. The validation of the developed mathematical model was performed using three process data sets with five process parameters obtained from industrial fixed-bed reactor. The simulation results showed a good agreement with the measured values for three kinetic models. The most influential inlet process parameters are inlet flow rates of n-butane and oxygen. The maleic anhydride yield is more sensitive to the changes of inlet process parameters than n-butane conversion and maleic anhydride selectivity. By increasing the inlet molar flow of n-butane for 20%, n-butane conversion and maleic anhydride yield are decreased for 3.3% and 5.0%, while maleic anhydride selectivity is increased for 6.7%. In order to increase the selectivity of maleic anhydride, it is necessary to decrease the inlet temperature of reaction mixture, the inlet pressure of reaction mixture as well as the inlet molar flow of oxygen, and to increase the inlet molar flow of n-butane.

Determination of the crucial functional groups in graphene oxide for vanadium oxide nanosheet fabrication and its catalytic application in 5-hydroxymethylfurfural and furfural oxidation

Abstract Graphene oxide (GO) sheets are emerging as a new class of carbocatalyst, and also a perfect platform for metal-oxide catalyst assembling. The oxygen groups on either side of GO basal plane can be functioned as the anchor by employing GO as scaffolds. Vanadium-oxo nanosheets (VON) were assembled onto the surface of GO material from homogeneously dissolved VO(acac)2 solution via a facile route. Control experiments with different methods prepared graphene materials illustrate the nucleation and fabrication process of VON on GO surface with detailed TEM and XPS investigation. The evolution of oxygen groups in graphene material was also investigated. Hydroxyl/epoxy in GO sheets was considered to be important and favorable for the fabrication of VON on GO surface. The developed material was shown to be an efficient and recyclable heterogeneous catalyst for aerobic oxidation of 5-hydroxymethyfurfural (HMF) and furfural into maleic anhydride. Up to 90.9% yield of maleic anhydride from HMF and 59.9% from furfural were achieved under optimized reaction conditions, the reaction rate difference between HMF and FAL was studied on the basis of oxidation mechanism and their molecular structures.

Gas phase oxidation of furfural to maleic anhydride on V2O5/γ-Al2O3 catalysts: Reaction conditions to slow down the deactivation

An alumina-supported vanadium oxide catalyst (13.9wt.% vanadium oxide) has been characterized by different techniques and tested in the gas phase oxidation of furfural. These studies have shown that the catalyst unavoidably deactivates by deposition of maleates and resins over the surface. Full regeneration is accomplished by burning off these deposits at 773K. The studies have also demonstrated that if the primary contact occurs at temperatures at which furfural conversion is low and then the temperature is increased in a low- to high-temperature mode, intense deposition of maleates and resins takes place and the catalyst is rapidly deactivated. The increase of the temperature does not result in removal of deposits but accelerates the deposition. Under this protocol, the yield of maleic anhydride never exceeded 30%, irrespective of the reaction conditions (temperature and O2/furfural mole ratio). In contrast, if the catalyst first contacts the reaction mixture at high oxidizing potential, then the rate of maleate and resin deposition is much slower, and so is the deactivation rate, and the catalyst can display a higher yield of maleic anhydride for a longer period of time. A high oxidizing potential can be attained at a high reaction temperature (close to full conversion). A higher oxidizing potential at a given high temperature can be accomplished by increasing the O2/furfural mole ratio. Thus, for example, first contacting the catalyst at 593K (full conversion), 1vol.% of furfural, and O2/furfural mole ratio=10, obtained an initial maleic anhydride yield of 68%, and the yield was still greater than 50% after 15h on stream. On contacting at 573K with 1vol.% furfural and 20vol.% O2, the maleic anhydride yield was initially close to 75% and was above 60% after 15h.

Effect of the catalyst pore structure on fixed-bed reactor performance of partial oxidation of n-butane: A simulation study

The effect of catalyst pore structure on n-butane oxidation to maleic anhydride in a fixed-bed reactor was investigated by numerical simulations. The micro- and macro-pore model of Wakao and Smith was applied to model the diffusion–reaction inside the catalyst pellet. The studied pore structure parameters were macro-pore porosity, mean macro-pore diameter and mean micro- pore diameter. A fixed-bed reactor was simulated with a detailed two-dimensional heterogeneous model under typical industrial conditions. Simulation results have demonstrated that the reactor performance is sensitive to the chosen pore structure parameters especially macro-pore porosity and mean micro-pore diameter. A bi-modal catalyst pellet with bigger macro-pores and smaller micro-pores is favored to achieve higher yields of maleic anhydride. This work highlights the potential of improving this process by pore structure optimization.

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

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.

How the Yield of Maleic Anhydride in n-Butane Oxidation, Using VPO Catalysts, was Improved Over the Years

Key patents for the oxidation of n-butane to maleic anhydride (MA) using V/P mixed metal oxides (VPO) have been analyzed to evidence the important parameters needed to optimize the catalytic behaviour. The important aspects for the optimization of the catalyst performance are the preparation of the precursor (VO)HPO4·0.5H20, its activation to form the active catalyst VO2P2O7 and a small amount of VOPO4, the methodology of the addition of promoters, and the shaping of the catalyst. Even small, sustainable improvements in the MA yield (>1 %) achieved by improved, modified or optimized catalysts are significant on an industrial scale with the world production of MA being a respectable 2.7 Million tons/year. Although substantial improvements in MA yield have been achieved industrially over the past 40 years by improving the VPO catalyst composition and by optimizing process operations; the MA process remains, as practiced today, one of the least efficient industrial selective oxidation processes. Therefore, a huge incentive exists in the field to improve the MA catalyst and process, which led us to search for clues towards this end by analyzing the pertinent patent literature, as reported here.

Transient Redox Activity of Vanadyl Pyrophosphate at Ambient and Elevated Pressure

Abstract The transient catalytic activity of vanadyl pyrophosphate (VPP) catalyst was studied at ambient and elevated pressure (4.1 bar) and a wide range of operating conditions. The range included the commercial operating conditions typical of fixed bed, fluidized bed and circulating fluidized beds (CFB) for the partial oxidation of n-butane to maleic anhydride (MA). The maleic anhydride yield improved by increasing the feed oxygen molar fraction, temperature and pressure. When the catalyst was cycled between an oxidizing (synthetic air) and a reducing environment; yield increased with an increase in the catalyst residence time in the oxidizing environment. This effect was more pronounced at higher pressure. At ambient pressure, MA selectivity varied between 50-73 % while it decreased to about 48-54 % at a pressure of 4.1 bar. A strong MA selectivity dependency on feed composition was observed when the oxidation time was in the range of actual industrial reactors (< 1 minute). Selectivity data suggested that different oxygen species might be responsible for CO formation compared to other products such as CO2 and MA. Under oxidizing feed conditions (oxygen/n-butane ≥ than 3.7), an increase in n butane conversion was the main contributor to improved MA yield: n-butane conversion increased by about 70 % when the catalyst oxidation time extended from 0.3 to 10 minute. While, under fuel rich feed conditions, typical of industrial CFB operations, both MA selectivity and n-butane conversion contributed to enhancement in MA yield. Depending on the feed composition, MA selectivity increases by about 16-30 % and n butane conversion increases by about 32-55 % by extending the catalyst oxidation time. These results show the critical importance of catalyst oxidation time on reaction yield improvement especially when operating under fuel rich feed conditions. The surface adsorbed or surface lattice oxygen species were suggested to be the main responsible for n butane activation. While, the contribution of catalyst’s sub-surface lattice oxygen was believed to be very limited at fuel rich feed conditions. Under these conditions, catalyst over-reduction cannot be effectively compensated even after excessive catalyst regeneration and presence of gas phase oxygen is critical to maintain a high catalytic activity. As the reactor pressure increased to 4.1 bar, up to 60 % increase in n butane conversion accompanied by 100 % increase in oxygen conversion was observed. MA selectivity decreased by about 20 % on average but the increase in n-butane conversion resulted in an overall yield improvement of up to 30 %. Data show that the catalytic performance could be enhanced at certain combination of reactor pressure and temperature.

Application of the flowsheet simulation concept to fluidized bed reactor modeling. Part II—Application to the selective oxidation of n-butane to maleic anhydride in a riser/regenerator system

In part I of this paper a new fluidized bed reactor module was presented for the simulation of a bubbling fluidized bed and of the riser of a circulating fluidized bed with the flowsheet simulation tool SolidSim so that several process models can easily be coupled. In the present part II the newly developed fluidized reactor modules are connected to existing cyclone modules to simulate a complex coupled fluidized-bed process, the selective oxidation of n-butane to maleic anhydride in a riser–regenerator system [1,2]. The calculation results for a laboratory setup are found to be in good agreement with experimental data from the literature. The subsequent simulation of an industrial scale sized plant shows that a high solids recirculation rate is needed to achieve satisfying maleic anhydride yield. The usefulness of flowsheet simulation is demonstrated by further process simulation calculations with varied solids recovery systems.

Innovative process for the synthesis of vanadyl pyrophosphate as a highly selective catalyst for n-butane oxidation

Vanadyl pyrophosphate (VPO) catalysts are used for the selective oxidation of light alkanes, which are based on vanadyl hydrogen phosphate hemihydrate (VOHPO 4·0.5H 2O) as the precursor. Catalyst precursor with well-defined crystal size has been successfully synthesized for the first time, using a simple one-step high-pressure autoclave that was surfactant-free and water-free method with significantly lower temperature and shorter reaction time. VOHPO 4·0.5H 2O was prepared from V 2O 5 using an isobutanol, 1-pentanol, 1-heptanol and 1-dectanol as both solvent and reducing agent at elevated temperatures (100, 120, and 150 °C). This new method significantly reduced the preparation time and lowered production temperature (50%) of catalyst precursor (VOHPO 4·0.5H 2O) when compared to conventional hydrothermal synthesis methods. VOHPO 4·0.5H 2O can be obtained at temperature far below 150 °C. It was found that the presence of 1-heptanol and 1-decanol in the reaction mixtures is crucial for obtaining a well-defined crystal size of precursor phase and solely generated impurity [VO(H 2PO 4) 2]. Our findings show that both the phase composition and morphology of vanadium phosphate can be influenced by the use of different reducing agents and temperatures during the preparation process. This new methodology produces catalysts with a much higher surface area ( ca. 23 m 2 g −1) compared with those materials prepared by slow hydrothermal synthesis ( ca. 9.5 m 2 g −1). Finally, the yield of maleic anhydride was significantly increased from 21.3% for conventional catalyst to 37.9% for the new solvothermal catalyst.

Maleic anhydride yield during cyclic n-butane/oxygen operation

Cycling catalyst between a net oxidizing and reducing gaseous environment has been practiced commercially to produce maleic anhydride from n-butane over vanadium pyrophosphate. Typically, the oxidation period is less than 1 min to minimize catalyst inventory. In this study, the effect of the oxidation period on maleic anhydride productivity was assessed in the range of 0.3–10 min. Irrespective of the feed gas composition during the reduction period, the productivity increased linearly with the oxidation soak time in air. A full range of reducing conditions was examined from the pure redox mode (10% n-butane in argon) to highly oxidizing conditions typical of fixed bed operation (1.4% n-butane and 18.1% oxygen). On average, maleic anhydride yield increased by up to 50% when the oxidation time was extended from 0.3 to 10 min. The maleic anhydride yield was lowest under redox mode and it was highest when the feed composition was close to equimolar in n-butane (∼6%) and oxygen. Our results show that industrial CFB reactor performance may be improved considerably by efficient regeneration of the catalyst and optimization of the reducing feed gas composition.

Novel Synthesis Techniques for Preparation of Ultrahigh-Crystalline Vanadyl Pyrophosphate as a Highly Selective Catalyst for n-Butane Oxidation

The vanadyl hydrogen phosphate hemihydrate (VOHPO 4 ·0.5H 2 O), with well-defined crystal size, has been successfully synthesized for the first time, using a simple one-step solvothermal process that was free of surfactants and water and had a short reaction time and low temperature. The synthesis was performed via the reaction of V 2 O 5 and H 3 PO 4 with an aliphatic alcohol (1-propanol or 1-butanol) at high temperatures (373. 393, and 423 K) in a high-pressure autoclave. The mixture of reactions directly gave the VOHPO 4 ·0.5H 2 O, which is a valuable commercial catalyst precursor for the selective oxidation of n-butane to maleic anhydride. The catalyst precursors were dried by microwave irradiation. The reaction conditions (by varying the reducing agent and reaction temperature) were used further for optimization of the crystallite size, surface area, morphology, and activity of the nanostructure of vanadium phosphate oxide [(VO) 2 P 2 O 7 ] catalyst. This new method significantly reduced the preparation time and lowered the production temperature (50%) of catalyst precursor (VOHP0 4 ·0.5H 2 O), when compared to conventional hydrothermal synthesis methods. The as-prepared (VO) 2 P 2 O 7 catalyst under various conditions exhibited remarkably different physical and chemical properties, indicating the potential of the suggested method in tuning the crystalline structure and surface area of (VO) 2 P 2 O 7 to improve its catalytic performance. It was found that the length of the carbon chain in an alcohol and reaction temperature in the solvothermal condition had a great impact on the chemical and physical properties of resulting catalysts. Interestingly, there was no trace of YO(H 2 PO 4 ) 2 , which is an impurity noted to be readily formed under solvothermal preparation conditions. The precursors and catalysts were characterized using a combination of powder X-ray diffraction (XRD), Brunauer-Emmett-Teller (BET) surface area measurement, scanning electron microscopy (SEM), and temperature-programmed reduction in hydrogen (H 2 - TPR). A correlation between the surface area of the catalyst and the activity was observed. Finally, the yield of maleic anhydride was significantly increased from 21% for conventional catalyst to 38% for the new solvothermal catalyst.

Effect of feed nozzle configuration on n-butane to maleic anhydride yield: From lab scale to commercial

In the process to produce maleic anhydride via the partial oxidation of n-butane, selectivity is sensitive to feed gas configuration of both oxygen and n-butane. Based on laboratory scale fluidized bed experiments, selectivity was superior when the n-butane was co-fed together with oxygen. When the oxygen and n-butane were fed separately through a distributor and a sparger, selectivity was highest when the sparger was closest to the distributor (independent of whether the n-butane was fed through the sparger and the oxygen through the distributor or vice versa). Various feed gas configurations were tested in a 4.2 m diameter commercial circulating fluidized bed reactor equipped with 926 spargers at three different levels. Maleic acid production rate increased by about 15% when oxygen was fed to a lower sparger 0.45 m above the distributor compared to when it was fed at a height of 1.9 m. These observations indicate that maintaining the catalyst in an atmosphere containing oxygen is important for overall n-butane conversion and maleic anhydride selectivity.

Solvothermal synthesis of vanadium phosphate catalysts for n-butane oxidation

In this paper, we have developed a simple, low-cost, template-free and surfactant-free solvothermal process for synthesis of vanadyl hydrogen phosphate hemihydrate (VOHPO 4·0.5H 2O) with well defined crystal size. The synthesis was performed by reaction of VPO 4·2H 2O with an aliphatic alcohol (isobutyl alcohol, 1-pentanol, 1-hexanol, 1-heptanol or 1-decanol). This afforded well crystallized VOHPO 4·0.5H 2O by solvothermal methods at 120 °C temperature. This new method significantly reduced the preparation time and lowered production temperature (50%) of catalyst precursor (VOHPO 4·0.5H 2O) when compared to conventional hydrothermal synthesis methods. By varying the reducing agent, the solvothermal evolution process from layered tetragonal phase VOPO 4·2H 2O to orthorhombic phase VOHPO 4·0.5H 2O was observed. It was found that the length of carbon chain in an alcohol in the solvothermal condition had a great impact on chemical and physical properties of resulting catalysts. Interestingly, there was no trace of VO(H 2PO 4) 2 an impurity noted to be readily formed under solvothermal preparation condition. Therefore, this study introduces a more facile synthetic pathway to V(III) compounds. In addition, the microwave-synthesized catalysts exhibited some properties superior to those of conventionally synthesized catalyst such as better stability, crystallinity, and catalytic activity in the production of maleic anhydride. The characterization of both precursors and calcined catalysts was carried out using X-ray diffraction (XRD), inductively coupled plasma-atomic emission spectrometer (ICP-AES), N 2 physisorption, temperature programmed reduction (H 2-TPR) and scanning electron microscopy (SEM). The XRD pattern of the active catalyst prepared by this solvothermal method confirmed the presence of smaller crystal size (between 6 and 13 nm along 0 2 0 planes) of vanadium phosphate catalyst with higher specific surface area. Finally, the yield of maleic anhydride was significantly increased from 29% for conventional catalyst to 44% for the new solvothermal catalyst.

Effect of the graft yield of maleic anhydride on the rheological behaviors, mechanical properties, thermal properties, and free volumes of maleic anhydride grafted high‐density polyethylene

AbstractThe rheological behavior, thermal properties, and molecular mobility of a series of maleic anhydride (MA) grafted high‐density polyethylenes were characterized and evaluated. The rheological behavior was studied with a Haake minilaboratory. The viscosity of the samples in their melt state decreased with an increase in the graft yield, and this could be attributed to the higher molecular mobility for samples with a higher degree of grafting. The thermal properties were investigated with dynamic mechanical analysis and differential scanning calorimetry. Positron annihilation lifetime measurements were used to study the effect of the degree of grafting on the chemical environment and the atomic‐scale free‐volume properties. It was found that the grafted MA group played a significant chemical inhibition role in positronium formation when the graft yield was low. The results also indicated that the higher the degree of grafting was, the broader the free‐volume distribution was. The relationship between the microstructure and rheological behavior is discussed. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008

Pressure Calcination of VPO Catalyst

Calcination and activation are critical steps in the transformation of vanadyl hydrogen phosphate hemihydrate (VPO precursorVOHPO4·0.5H2O) to vanadyl pyrophosphate (VPO catalyst(VO)2P2O7). Whereas many published kinetics studies for butane oxidation over VPO demonstrate the relationship between catalytic activity and reaction conditions, the relationship between calcination conditions and activity has only received superficial attention in the open literature. This study delineates the operating boundaries in which to optimize catalytic performance. The control variables included temperature, pressure, time, and gas-phase composition (principally, oxygen and water vapor partial pressures), and their effects on surface area, oxidation state, and catalytic activity were measured. The experimental plan included several hundred calcination experiments. The commercial-design operating conditions were chosen as the base-case conditions: temperatures from 330 to 460 °C, pressures up to 6 atm, and oxygen and water concentrations between 0 and 20% and 0−3%, respectively. The optimal temperature was found to be about 390 °C. Catalyst performance declines with increasing pressure, but the pressure−time relationship allows a range of conditions: optimal catalytic performance was achieved within 20 h of calcination at atmospheric pressure, but it took less than 4 h to achieve this high level of performance when precursor was calcined at 3.5 atm (at longer times, the catalytic performance deteriorated). Co-feeding steam (in the presence of oxygen) generally had a deleterious affect on catalyst performance and, in particular, maleic anhydride yield. Moreover, oxidation states higher than 4.5 were achieved with steam/oxygen mixtures in as little as 20 h. Catalyst performance declined linearly with oxidation state for precursor calcined to vanadium oxidation states exceeding 4.5.

Maleic Anhydride from Mixtures of n-Butenes and n-Butane: Simulation of a Production-Scale Nonisothermal Fixed-Bed Reactor

The partial selective oxidation of mixtures of n-butenes and n-butane in an industrial-scale fixed-bed reactor has been simulated to find suitable operation conditions and to give a rough estimate of the performance of such a reactor. A two-dimensional homogeneous reactor model has been used in combination with a kinetic model based on experimental results. Since the pressure drop along the reactor tubes was assumed to be 1−1.5 bar, the gas phase in the reactor tubes had to be treated as a compressible fluid. The operation conditions of the reactor were found by repeated simulation and continuous improvement. The simulations resulted in a conversion level of 90% and a yield of maleic anhydride of 48% for a synthetic raffinate II mixture containing only n-butenes and n-butane. A typical real raffinate II mixture which also contains isobutane would result in a yield of maleic anhydride of ≈42%. Production capacities of 17 100 and 22 5000 t/y where achieved with allowed pressure drops of 1.0 and 1.5 bar, respectively.

Maleic Anhydride from Mixtures of n-Butenes and n-Butane: Effective Reaction Kinetics

The conversion of mixtures of n-butane and n-butenes to maleic anhydride over an industrial vanadium−phosphorus oxide (VPO) catalyst was experimentally investigated. Specifically, the conversion of a synthetic raffinate II mixture was studied. The reaction kinetics were modeled on the basis of a reaction network consisting of eight individual reactions and by using hyperbolic rate equations. Calculations and experimental results are shown for a temperature range from 400 to 450 °C and for molar fractions of the synthetic raffinate II in the feed that were varied from 1% to 2%. The kinetic model shows good agreement with the experimental results. The value of the maximum yield of maleic anhydride is insensitive to changes in temperature and hydrocarbon feed fractions and amounts to ∼48%. Increases in temperature, however, reduce the amount of catalyst required to reach the maximum yield. The conversions of pure 1-butene and pure n-butane lead to maximum yields of ∼53% and 56%, respectively. The efficiency ...