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The partial oxidation of acrolein and methacrolein on Mo/V/W-mixed oxides was studied by transient kinetic investigation with a new experimental technique. Within the so‑called HETKA (Homologue Exchange Transient Kinetic Analysis) experiments, acrolein (ACR) was stepwise replaced by methacrolein (MAC), and vice versa under constant reaction conditions. Conversion and yield decrease significantly when ACR is substituted by MAC. Evidence is given that the lower reaction rate with MAC is caused by the formation of coke deposits on the catalyst surface. Furthermore, a temperature programmed reaction (TP reaction) was carried out in which both aldehydes were fed at the same time. Compared with the TP reactions with only one aldehyde, the conversion and yield curves are shifted to higher temperatures. Regarding acrylic acid, the maximum yield and selectivity are not influenced by the contemporaneous presence of both aldehydes. On the contrary, the selectivity to methacrylic acid is increased significantly.

Manipulation of carbon surface functionalization and especially of oxygen surface groups has been demonstrated to be key for obtaining high performance materials in a multitude of applications. Although control of carbon surface chemistry offers large potential in many technical relevant applications, qualitative and quantitative analysis of surface oxides for amorphous and porous carbons remains challenging. In this study, we attempt selective, organic chemistry-based functionalization of a polymer-derived porous model carbon featuring high oxygen loadings, with the aim to establish analytical standards for temperature programmed desorption (TPD) and diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS). In this context, quantitative chemical reduction of an oxidized carbon material with lithium aluminum hydride (LiAlH4) is utilized as the key for the synthesis of carbon materials with defined ensembles of oxygen surface groups (hydroxyl groups and ethers). Based on this reduction strategy, selective LiAlH4 reduction based on protection group chemistry leads to aldehydes, ketones and quinones as surface functional groups and chemical grafting is studied for the selective introduction of phenyl esters, methyl ethers and carboxylic acids. All materials are evaluated with respect to the applicability as analytical standard by DRIFT spectroscopy, TPD, X-ray photoelectron spectroscopy and titration methods.

Catalytic conversion of n-butanol to high-value-added product is considered as a highly important route towards biomass derived fine chemicals. The present work reports the applications of non-metallic multi-walled carbon nanotube (CNT) as bifunctional catalysts for oxygen assisted n-butanol conversion reactions. Oxidative dehydrogenation (ODH) and dehydration of n-butanol on CNT yielded aldehyde and alkene compounds via redox and acid catalytic routes, respectively. CNT exhibited high activity (over 50% n-butanol conversion) and stability (over 120 h) under gentle reaction conditions (

A liquid core waveguide membrane microreactor is a novel concept that allows in situ spectroscopy to be carried out in an optical microreactor, while enabling a very high gas-to-liquid mass transfer. The potential of this reactor concept to derive kinetics in gas/liquid reactions is demonstrated using the heteropoly acids catalyzed oxidation of biomass to formic acid (the ‘OxFA process’). For vanadium-substituted, Keggin-type heteropoly acids, the kinetics of the reduction and reoxidation step of the catalyst cycle was deduced using in situ UV/Vis spectroscopy. Reduction was studied from 40 to 80 °C: a strong dependency of the reduction kinetics was deduced. In combination with additional cyclic voltammetry and EPR characterization, it can be assumed that two active centers promote this reaction, while the existence and proportions of both types depends on the degree of vanadium substitution. The rapid mass transfer allowed transient response experiments to be carried out for the reoxidation step, which was studied up to 150 °C. Switching from anaerobic to aerobic conditions, an even stronger dependency of the reoxidation kinetics on the degree of vanadium substitution was revealed.

A new strategy affords “non‐nano” carbon materials as dehydrogenation catalysts that perform similarly to nanocarbons. Polymer‐based carbon precursors that combine a soft‐template approach with ion adsorption and catalytic graphitization are key to this synthesis strategy, thus offering control over macroscopic shape, texture, and crystallinity and resulting in a hybrid amorphous/graphitic carbon after pyrolysis. From this intermediate the active carbon catalyst is prepared by removing the amorphous parts of the hybrid carbon materials via selective oxidation. The oxidative dehydrogenation of ethanol was chosen as test reaction, which shows that fine‐tuning the synthesis of the new carbon catalysts allows to obtain a catalytic material with an attractive high selectivity (82 %) similar to a carbon nanotube reference, while achieving 10 times higher space–time yields at 330 °C. This new class of carbon materials is accessible via a technically scalable, reproducible synthetic pathway and exhibits spherical particles with diameters around 100 μm, allowing unproblematic handling similar to classic non‐nano catalysts., An amorphous/graphitic hybrid material is synthesized by growing nanoscale graphite crystallites in a non‐nano polymer‐derived carbon by catalytic graphitization. An active dehydrogenation catalyst is obtained by creating accessibility to these graphitic domains via selective oxidation. This carbon dehydrogenation catalyst offers a 10‐fold increase in space‐time‐yield in the oxidative dehydrogenation of ethanol compared to a carbon nanotube benchmark.

Oxidation of acrolein to acrylic acid on a Mo/V/W mixed oxide catalyst was studied by transient (cyclic temperature-programmed (TP)) as well as steady-state methods. TP reactions (TPReactions) exhibit an activity hysteresis of the catalyst with respect to temperature. As a result of the steady-state measurements, the activity hysteresis is not related to multiple steady states and is exclusively a transient phenomenon. Generally, the dynamics of bulk oxygen plays a key role leading to a reversible oxidation/reduction of the catalyst surface which influences the activity. This means the bulk acts as oxygen buffer. In this context, a reaction model, which involves the participation of bulk oxygen, was deduced and verified by modeling.

Interest in energy storage technologies is still increasing in times of the excess of electricity that is generated by wind farms or solar plants. Solar electricity can be transformed to solar-hydrogen via water electrolysis. A crucial part of the energy storage technologies plays the efficient conversion of H2 and CO2 from renewable resources. Here, the process conditions for continuously catalytic hydrogenation of CO2 to CH3OH under supercritical conditions over lab-synthesized Cu/ZnO/Al2O3 catalysts were investigated. The impact of temperature (230 – 330 °C), residence time (0.5 - 2.2 s) at moderate pressure (150 bar) but even above the supercritical parameters of CO2 showed a selective CO2 hydrogenation. Higher H2 concentrations, respectively higher H2:CO2-ratios (H2:CO2 = 6), lead to an increased selectivity of CH3OH. A possible in situ phase separation of reaction products within the reactor due to the higher densities of the reaction mixture by the highered pressure could affect the kinectics and simplfy the down-stream processing. The combination of thermodynamic studies (phase separation phenomena) as well as the catalytic performance tests for the CO2 hydrogenation under supercritical conditions are discussed. Based on these data a process concept is presented.

Zur besseren Nutzung von Exzessenergien wurde ein Warmespeichersystem entwickelt, das sich aus einem Blockheizkraftwerk (BHKW) mit einem integrierten Langzeitwarmespeicher zusammensetzt. Aus okonomischen Grunden wird ein BHKW ganzjahrig bei optimalem Wirkungsgrad betrieben. Die Folge ist, dass Warmeenergie im Sommer sinnvollerweise gespeichert werden sollte, um sie in der Heizperiode zu nutzen. Hierbei wird als Warmespeichersystem ein binares System bestehend aus einem modifizierten Zeolith 5A und Ammoniak eingesetzt. Die abschliesende Auslegung zeigt, dass es als Kurz- und Langzeitwarmespeicher eingesetzt werden kann.

During the acrylic acid (AA) storage a quality loss occurs due to the formation of by-products such as diacrylic acid (DiAA), triacrylic acid (TriAA) and higher oligomers. This problem intensifies in the presence of water since the formation rate of oligomers increases and further byproducts such as 3hydroxypropionic acid (3-HPA) and 3hydroxydiacryl acid (3-HDiAA) are formed. However, water is often essential during storage and transport to rise the flashpoint or to reduce the melting point. In the literature only the formation of DiAA has been investigated. In this work the formation kinetics are investigated for all mentioned components at 100 °C in pure and aqueous AA containing 5, 10 and 20 wt% water. The formation mechanisms of 3-HPA and 3-HDiAA are assumed as acid catalyzed ester hydrolyses of DiAA or TriAA. The hydration of AA to 3-HPA is excluded because the formation process does not exhibit a second order kinetic reaction. The introduced reactions are modelled with the measured kinetic data in order to confirm the proposed reactions.

To diversify energy sources and to address the impacts of global warming, the transformation of biomass, a renewable energy source, into fuels and chemicals is becoming increasingly necessary. The gasification technology is an efficient way of converting biomass via syngas into sustainable fuels. By-products, especially tar, are formed during the gasification process and need to be removed before further downstream processing. Mo/V/W-mixed oxides were found to be applicable for the catalytic tar oxidation in CO/H2 atmosphere by adding a stoichiometric amount of oxygen. In temperature-programmed experiments the reactivity of different tar model compounds during the selective oxidation on Mo/V/W-mixed oxides as well as the catalytic performances of V2O5, WO3, and MoO3 during the tar oxidation were investigated.

The partial oxidation of unsaturated aldehydes such as acrolein and methacrolein to the corresponding carboxylic acids is of big importance for the chemical industry. The heart of these production plants is the oxidation catalyst. Acrylic acid is produced via the selective oxidation of acrolein on Mo/V/W mixed oxides with an excellent catalytic performance (S > 90 %, X > 95 %, life time >3 a). Under the same conditions the conversion of methacrolein to methacrylic acid has a poor catalytic performance (S

A new experimental setup is introduced, enabling a preheated exhaust gas mixture to abruptly heat up an initially cold monolith catalyst and, thus, reproduce transient catalyst light-off behavior. With this setup, cold start experiments have been carried out on an aged monolithic Pd three-way catalyst (TWC). This study aims at systematically investigating the effect of diverse hydrocarbons, including methane, acetylene, ethene, ethanol, acetaldehyde, propane, propene, toluene, and xylene in TWC exhaust. It was shown that the commonly used model components propane and propene do not represent the behavior of aromatics and other hydrocarbons present in a typical TWC exhaust very well, since they do not account for their variability in inhibition strength and reactivity. Among the studied hydrocarbons, acetylene proved to be the strongest inhibitor; even at low concentrations of 70 ppm (a typical value found in TWC exhaust), acetylene inhibition increases CO cold-start emissions by 40 %. Furthermore, aromatic and liquid hydrocarbon species (like ethanol) first condense on the initially cold catalyst surface and evaporate again as the catalyst heats up, resulting in a desorption peak at the catalyst outlet.

In today’s vehicle applications, SCR ammonia dosing is completed using complex control algorithms that need to be parameterized for the individual catalyst technology. Owing to the complexity of the parameterization procedures, ammonia dosing is frequently completed using either oversimplified dosing strategies (e.g., constant NH 3 /NO x ratio) or strategies previously optimized for different catalysts during the early design phase’s simulation and laboratory studies. This paper presents a practical, model-based approach that allows for simulation and laboratory studies to be performed with an individually adapted dosing profile. The procedure is based on conventional feedback control strategies, where the average ammonia storage level is controlled using a temperature dependent setpoint (the desired storage level), which is interpolated from a look-up table. The approach of this paper is to optimize numerically the entries of this look-up table for a given test cycle such that the NO x conversion is maximized while the ammonia slip is kept below a defined level. Although the optimization is performed for a particular cycle, it is demonstrated that the dosing strategies obtained in this way also work reasonably well for other test cycles. The proposed procedure was applied in a catalyst screening simulation study that compared the performance of an Fe– and a Cu–zeolite catalyst for a given test cycle. It was demonstrated that each of the two catalysts appeared to have a better performance than the other catalyst when the specified catalyst’s optimized dosing profile was applied to both catalysts. The best catalyst was only identified when comparing both catalysts using their own respective optimized dosing profile. A second simulation study used the proposed dosing procedure to compare catalysts with different ammonia storage capacities. Again, the relative ranking of the catalysts’ performance was shown to depend on the dosing profile. Overall it is demonstrated that the true potential of a catalyst can only be determined when an individually adapted dosing strategy is used.

Oxidation of acrolein to acrylic acid on Mo/V/W-mixed oxide catalysts has been studied by means of the isotopic exchange method steady-state isotopic transient kinetic analysis (SSITKA). As a result of these isotopic exchanges performed with 16O2 and 18O2, some new mechanistic details could be obtained. Acrolein exchanges its oxygen with oxygen of the mixed oxide catalyst. Additionally, the kinetics of the different isotopologues is significantly influenced by oxygen exchange reactions between the surface and the bulk sites. From the SSITKA results, an extended reaction model has been deduced. Thus, the experimentally gained data of the individual isotopologue kinetics could be verified by modeling.

Die hydrothermale Carbonisierung (HTC) ist in Hinblick auf die energetische Verwertung von Biomasse eine vielversprechende Methode. Trotz der langen Historie dieses Verfahrens sind Mechanismus und Kinetik nur unzureichend verstanden. In den hier vorgestellten Experimenten wurde mithilfe der Kombination von Analysenmethoden die Umsetzung von Kohlenhydraten mit sauren und basischen Zusatzen untersucht. Dabei konnte vor allem der Einfluss von Saure auf die Hydrolyse von Cellulose beobachtet werden. Die HTC von Glucose hingegen bleibt weitestgehend von den Zusatzen wie Saure oder Base unbeeinflusst. Durch Veranderung der Reaktionsbedingungen wie der Heizrate konnen die Biokohle-Eigenschaften wie z. B. die Aciditat der Kohle variiert werden. In terms of energy recovery, the hydrothermal carbonization (HTC) is a promising method. Despite the long history of this process, the mechanism and kinetics are poorly understood. For tracing the reaction kinetics a combination of analysis methods has been used. In the presented study the HTC of carbohydrates is examined with addition of acid and base. Thereby, a major influence of acids on the hydrolysis of cellulose can be observed. The HTC of glucose, however, remains largely unaffected by these additives. Furthermore, it was observed that reduced heating rates lead to changes in the biochar acidity.

This paper demonstrates that the use of a solution-mapping approach can accelerate the simulation of a dual-layer ammonia oxidation catalyst by several orders of magnitude. In a first step, a 1-D + 1-D model of the dual-layer catalyst is set up. The results of this model are compared to the numerical solution of a 2-D model, and it is shown that the 1-D + 1-D model provides an accurate approximation of the full 2-D solution. In a second step, spline interpolation functions are constructed that map the solution of the mass balance equations for one axial volume element of the 1-D + 1-D model as a function of the inlet concentrations, temperature and residence time. During the runtime of the simulation, concentration profiles can be computed by simple successive calls of the interpolation function without the need for a numerical solver. The 5-dimensional spline functions reproduce the output concentrations of a reactor model with 35 axial volume elements with an accuracy of better than 1.25%. The use of the solution mapping reduces the computation time for a steady-state solution of the monolith model from 97.5 s down to 10 ms.

The influence of water on the selective gas phase oxidation of acrolein to acrylic acid on Mo/V/W-mixed oxides was investigated by means of temperature-programmed experiments. In the presence of water, the rate of the acrylic acid formation is significantly pronounced. Selectivity- and yield-maxima are broadened and shifted towards lower temperatures. Nonetheless, the combustion remains unaffected. Furthermore, the catalysts stability remains likewise unaffected within the range of the experiments.

Mittels der Isotopenaustauschmethode SSITKA (steady-state isotopic-transient kinetic analysis) ergaben sich Ruckschlusse zum Mechanismus der Partialoxidation von Acrolein zu Acrylsaure an Mo/V/W-Mischoxidkatalysatoren. Der Isotopenaustausch erfolgte mit den beiden Sauerstoffisotopen 16O2 und 18O2. Dabei findet am Katalysator ein Austausch des Carbonylsauerstoffs im Acrolein mit Festkorpersauerstoff statt. Zusatzlich wird die Kinetik der unterschiedlichen Isotopologenspezies durch eine Austauschreaktion von Sauerstoff zwischen belegten und unbelegten Zentren an der Oberflache und in der Volumenphase des Katalysators signifikant beeinflusst. Gestutzt durch einen erweiterten Modellvorschlag zum Mechanismus konnten uber Simulationen die experimentell gewonnenen Isotopologenkinetiken verifiziert werden. The partial oxidation of acrolein to acrylic acid on Mo/V/W-mixed oxide catalysts has been studied by means of the isotopic exchange method SSITKA (steady-state isotopic-transient kinetic analysis). In the scope of isotopic exchanges performed with the oxygen isotopes 16O2 and 18O2 some new details could be gained regarding the mechanism. Acrolein exchanges its oxygen with oxygen of the solid catalyst. Additionally the kinetics of the different isotopologues is influenced by another exchange reaction of oxygen between vacant and occupied surface and bulk sites. From the SSITKA results an extended model has been deduced. So, the experimentally gained data of the individual isotopologue kinetics could be verified by simulation.

For a safe storage and handling of acrylic acid (AA), a lot of knowledge is necessary. In the present work, investigations were made in order to describe the stabilization processes during the inhibition period (IP) of AA more exactly. The oxygen and p-methoxyphenol consumption was determined for AA at 70 and 80 °C in an enhanced parameter range and simulated with a kinetic model, using the software Presto Kinetics (R). In the simulation accelerated stabilizer consumptions at 80 °C could be confirmed. The known stabilization mechanism must be enhanced with autocatalytic steps, which lead to an accelerated stabilizer consumption. Furthermore, the stability of AA was examined as a function of the dissolved oxygen mass fraction and the temperature in isoperibolic reactors. The IP follows an Arrhenius behavior; therefore, an extrapolation from higher reaction temperatures to storage conditions is possible. These measurements also confirm the nonlinear stabilizer consumption during the IP at temperatures over 75 °C.

Copper catalysis proceeds with multiple steady states and oscillations in several oxidation reactions. The understanding of such kinetic phenomena is essential for the control of copper-catalyzed industrial scale processes. Information about the reasons and the ranges of the parameters causing these kinetic effects will be given from results gained by concentration programmed reaction (CP-reaction) experiments. Elemental copper was used as unsupported catalysts and the oxidation of hydrogen and ethanol were introduced as model reactions. CP-reaction experiments were performed in a tubular reactor as well as in a differential thermal gravimetric analyzer (TG/DTA). The application of a TG/DTA as a reactor gave the opportunity for a simultaneous measurement of the activity and the grade of oxidation of the copper catalyst.

This paper demonstrates how pre-computed rate data can be used to enable the numerically efficient implementation of mechanistic kinetics in a reactor model for an automotive ammonia slip catalyst. In a pre-processing step the source terms for the gas species are mapped as a function of gas composition and temperature. From this map (80,000 data points), a spline interpolation function is constructed. The spline function approximates the numerical steady state solution of the kinetic model with an average error of less than 1%. Application of the rate mapping procedure results in a speedup of about two orders of magnitude. The spline approximation is implemented in a 2-dimensional model of a monolith reactor channel that includes diffusion in the washcoat layer. Depending on the channel diameter and the washcoat thickness, diffusion limitations in the open channel and in the washcoat can have a significant influence on the NH 3 conversion. Surprisingly, the selectivity for the products N 2 , N 2 O and NO is not sensitive to diffusion effects in the gas phase or in the washcoat.

The aim of this investigation is to quantify surface oxygen groups on an activated carbon by combining the results from temperature programmed desorption (TPD) and diffuse reflectance FT-IR spectroscopy (DRIFTS). A commercial activated carbon was oxidized with ozone to form surface oxygen groups. Afterwards the samples were heated in TPD experiments up to 500 °C. The evolved gases were detected and quantified via IR spectroscopy and DRIFT spectra were collected from the heat-treated samples. Simulation of the DRIFT spectra with a set of Gauss functions led to identification of four surface oxygen groups in the range of 1500–1950 cm −1 . Specific concentrations of the four groups can be calculated with the conversion factors obtained by combining TPD and DRIFTS information.

The setup of a detailed model for the NH3-SCR process on iron exchanged zeolite catalysts is described, which takes into account the reactions of NH3, NO and NO2 occurring under typical exhaust conditions. Validation experiments for a standard SCR gas mixture show that the model is able to describe the dynamic behaviour of this system at transient temperature conditions. The model is used for the parameterization of an ammonia dosing controller. To prove the functionality of this controller it was implemented on a synthetic gas test bench and tested by a dynamic temperature experiment. This setup allows the evaluation of the parameterized controller without any disturbances from engine or injection effects.

A microkinetic model is developed for the NO-oxidation on platinum. The approach we followed employs semi-empirical methods, optimization of the parameters of elementary-like reactions, and thermodynamic constraints. The model is capable of capturing reasonably light-off experimental data.

The oxidation of ammonia on a Pt/Al2O3 coated monolith has been studied under automotive NH3-slip catalyst conditions. Ammonia conversion as well as the selectivities towards the products N2, N2O and NO are well described by a mechanistic model that is based on reaction mechanisms originally developed for NH3 oxidation in nitric acid production plants.

The storage of NO, NO/O2-mixtures and NO2 on CeO2 and BaO/CeO2 was investigated by in situ DRIFT-spectroscopy. The NOx-storage capacity, as well as the kinetic and the mechanism of the NOx-storage process are influenced by the temperature and the BaO-loading as well as the oxygen partial pressure. The addition of oxygen into NO containing gas mixtures results in the oxidation of the stored nitrite to nitrate species. Adsorption of NO2 leads to in the formation of nitrite and nitrate species, where the nitrite species are completely oxidized to nitrate in the progress of storage.

The dynamic behaviour of the NO SCR-reaction on Fe-exchanged zeolites was investigated by the transient response method (TRM). The results were used to develop a mathematical model for catalysts containing Fe-exchanged zeolites capable of describing the dynamic phenomena observed.

Different global kinetics for the oxidation of NO on platinum are compared in this work. The general form of the equation for the reaction rate is $r = k \cdot c_{NO}^\alpha \cdot c_{O_2 }^\beta \cdot c_{NO_2 }^\gamma \cdot TD^\delta$ with $TD = \left( {1 - c_{NO_2 } \cdot c_{NO}^{ - 1} \cdot c_{O_2 }^{ - 0.50} \cdot K^{ - 1} } \right)$ . Furthermore steady-state and temperature-programmed experiments were performed. The best results of simulation coupled with parameter estimation were obtained using α = 0.28, β = 0.49, γ = 0 and δ = 1, along with an activation energy of 47.5 kJ mol−1.

This paper presents experimental and modelling results for the oxidation of mixtures of hydrogen and carbon monoxide in a lean atmosphere. Transient light-off experiments over a platinum catalyst (80 g/ft 3 loading) supported on a washcoated ceramic monolith were performed with a slow inlet temperature ramp. Results for CO alone agree with earlier results that predict self-inhibition of CO; that is an increasing light-off temperature with increasing CO concentration. Addition of hydrogen to the feed causes a reduction in light-off temperature for all concentrations of CO studied. The most significant shift in light-off temperature occurs with the addition of small amounts of hydrogen (500 ppm, v/v) with only minor marginal enhancement occurring at higher hydrogen concentrations. Hydrogen alone in a lean atmosphere will oxidise at room temperature. In mixtures of hydrogen and CO, the CO was observed to react first until a conversion of about 50% was observed, at which point the conversion of hydrogen rapidly went from 0 to 100%. Simulations performed using literature mechanistic models for the oxidation of these mixtures predicted that hydrogen ignites first, followed by CO, a direct contradiction of the experimental evidence. Upon changing the activation energy between adsorbed hydrogen and oxygen, the CO was observed to oxidise first, however, no enhancement of light-off was predicted. The effect cannot be explained by the mechanistic model currently under discussion.

Diesel particulate filters composed of so-called wall-flow monoliths are well established devices for diesel particulate abatement. Recent improvements in production technology allow implementation of full-featured catalyst functionality in the filter walls. From a reactor engineering point of view such wall-flow reactors with wall-integrated catalyst show fundamental differences compared to conventional flow-through monoliths. The complex interactions of convection, diffusion and reaction in the wall-flow monolith are studied by means of numerical simulation. A two-dimensional model for the flow in one pair of inlet/outlet channels with a generic first order reaction in the catalytic filter wall is developed. Concentration profiles in the reactor and a conventional flow-through catalyst are compared. It is found that in the range of moderate reactor conversion concentration gradients along the inlet channel of the filter are small. Thus the reactor can be described by an approximate one-dimensional model, taking into account only the radial flux through the filter wall and assuming a constant inlet concentration in axial direction along the inlet channel. Light-off curves are computed for the wall-flow and for the conventional flow-through monolith. Significantly better conversion is found for the wall-flow configuration. This can be explained by mass transfer limitation in the conventional flow-through monolith.

NO adsorption and NO/O2 co-adsorption on CeO2 at different temperatures was studied by DRIFT-Spectroscopy. The results indicate that this oxide plays an important role in storing NO x . FTIR studies show that NO adsorption is dominated by the formation of nitrite species. Furthermore, cis- and trans hyponitrite species are detected. Co-adsorption of NO/O2 leads to the formation of nitrates. The experimental data show that the formation of nitrates is a consecutive reaction: adsorption of NO to form nitrite species (NO2 −), followed by an oxidation to form nitrate species (NO3 −).

The applicability of Mo/V-mixed oxides for the partial oxidation of isobutyraldehyde to methacrolein is examined. The results are compared with the catalytic performance of a heteropolyacid-catalyst.

IR spectroscopy is a well-established method in the characterization of heterogeneous catalysts under reaction conditions. Working in transmission modes is the most common of currently applied technologies. Yet, there are problems inherent in both methods (KBr wafers and self-supporting wafers) for the in-situ investigation of heterogeneously catalyzed reactions. These problems can be avoided by using the DRIFT (diffuse reflection infrared Fourier transformation) spectroscopy. As is shown in this study, DRIFT spectroscopy proves to be a suitable method producing not only qualitative but also quantitative results of in-situ examinations of heterogeneous catalysts.