Higher Hydrocarbon Production through Oxidative Coupling of Methane Combined with Hydrogenation of Carbon Oxides

In the production of higher hydrocarbons, combining oxidative coupling of methane (OCM) with hydrogenation of the formed carbon oxides in a separate reactor provides an alternative to the currently applied methane conversion to syngas followed by Fischer‐Tropsch synthesis. The effects of CH₄:O₂ feed ratio in the OCM reactor and partial pressures of H₂ or/and H₂O in the hydrogenation reactor were analyzed to maximize production of C₂₊ hydrocarbons and reduce CO_x formation. The highest C₂₊ yield was achieved with low CH₄:O₂ feed ratio for OCM and removal of the formed water before entering the hydrogenation reactor.     

High-throughput preparation and screening of rhenium oxide-alumina catalysts in olefin metathesis

High-throughput (HT) experimentation in heterogeneous catalysis exemplifies a multidisciplinary approach to address in an efficient manner different aspects of catalyst development – from synthesis to testing and characterization. The present work reports on preparation systems for rapid parallel synthesis of well defined heterogeneous catalysts and catalyst screening in olefin metathesis. Metathesis of ethene and but-2-ene to propene was chosen as a test reaction. The influences of various parameters such as rhenium oxide loading, catalyst calcination conditions, catalyst pre-treatment, as well as the reaction temperature and contact time on the catalytic performance are discussed. Sample characterization by UV–vis and FT-IR gave an evidence for the formation of active surface perrhenate species, very sensitive to humidity and pre-treatment conditions applied.     

The reaction network of the selective oxidation of n-butane on (VO)2P2O7 catalysts: Nature of oxygen containing intermediates

The reaction network of the partial oxidation of n-butane to maleic anhydride on (VO)₂P₂O₇ has been investigated using steady-state and transient experiments in a Temporal-Analysis-of-Products (TAP) reactor under vacuum conditions to identify by mass spectrometry possible intermediate products and in a tubular fixed bed reactor at atmospheric pressure to derive information on the role of the detected and other potential intermediates in the reaction network. The oxidation of butane, butadiene, tetrahydrofuran, dihydrofuran, and furan has been studied in the TAP reactor and, additionally to these compounds, crotonaldehyde, crotonlactone, and malealdehydic acid were oxidized in the tubular flow reactor. From the results obtained it can be concluded that the main reaction pathway from butane to maleic anhydride proceeds via the intermediate products n-butenes, butadiene, crotonaldehyde, dihydrofuran, furan, and crotonlactone.     

Design of an X‐Ray Powder Diffraction Probe for Multi‐Channel Application: Proof of Principle

The design of an X‐ray powder diffraction probe and its integration with a multi‐channel reactor system for potential application in high‐throughput experimentation is presented. The working principle of the apparatus is exemplified by measurements of corundum and of the phase change observed when oxidizing vanadium(III) oxide (V₂O₃) in air during heating up to 450 °C. The phase transformations of the parent material were monitored by phase identification of the crystalline intermediate vanadium(IV) oxide (VO₂) and the final product vanadium(V) oxide (V₂O₅).     

Generator approach to evolutionary optimization of catalysts and its integration with surrogate modeling

This paper presents some unpublished aspects and ongoing developments of the recently elaborated generator approach to the evolutionary optimization of catalytic materials, the purpose of which is to obtain evolutionary algorithms precisely tailored to the problem being solved. It briefly recalls the principles of the approach, and then it describes how the employed evolutionary operations reflect the specificity of the involved mixed constrained optimization tasks, and how the approach tackles checking the feasibility of large polytope systems, frequently resulting from the optimization constraints. Finally, the paper discusses the integration of the approach with surrogate modeling, paying particular attention to surrogate models enhanced with boosting. The usefulness of surrogate modeling in general and of boosted surrogate models in particular is documented on a case study with data from a high-temperature synthesis of hydrocyanic acid.     

Economic Assessment of the Hydrogenation of CO2 to Liquid Fuels and Petrochemical Feedstock

To remove high concentrations of CO₂ from the off‐gas of coal‐driven power plants, a new process was proposed. The catalytic hydrogenation of the CO₂ leads to the production of C₂ – C₄ (petrochemical feedstock) and liquid C₅₊ hydrocarbons (fuel). Thus, environmentally harmful CO₂ may be converted sustainably to useful products. On the basis of a process flow sheet, the costs for processing the CO₂ are estimated for different plant sizes. The price of hydrogen contributes significantly to the overall production costs. Further price reductions may be achieved by final engineering optimization of the process as a whole and specific unit operations.     

A novel multi-channel reactor system combined with operando UV/vis diffuse reflectance spectroscopy: Proof of principle

A 36 channel reactor system combining high-throughput experimentation (HTE) with operando UV/vis diffuse reflectance (UV/vis-DR) spectroscopy is introduced and applied for the oxidative dehydrogenation of propane (ODP) to propene at 500 °C over polycrystalline V₂O₃, VO₂, and V₂O₅. This set-up enabled to monitor reaction-induced reduction of V₂O₅ to V₂O₃, and VO₂ during the ODP reaction. The operando UV/vis-DR spectroscopic analysis along the catalyst bed demonstrated that the vanadium oxidation state at the reactor inlet is higher than at the reactor outlet. This is due to the depletion of oxygen and the enrichment of propene down stream along the catalyst bed.     

Low-temperature CO2 reforming of methane over Ni supported on ZnAl mixed metal oxides

Ni catalysts supported on mixed ZnOAl₂O₃ and on pure ZnO and Al₂O₃ were prepared, characterized by XRD, TPR, and XPS, and tested in long-term methane dry reforming at low temperature (400 °C). Depending on Zn/Al ratio in the supports, the catalysts varied in their physico-chemical properties and exhibited different trends in their on-stream catalytic activity. Catalysts with high alumina content consist of a mixture of alumina and zinc aluminate phases with metallic Ni particles on their surface. These samples show medium activity for reforming and high on-stream stability. The catalysts on mixed Zn-rich supports were more active than those on Al-rich supports and exhibited maxima in their activity after 30–40 h on stream, while Ni on pure ZnO possessed very low activity. Such contrast in performance of Zn-rich catalysts was explained by detected transformation of initially formed NiZn alloy to a mixture of Ni and Ni₃ZnC_0.7 particles that are assumed to have higher activity for reforming. Moreover, the size of Ni-containing particles on Zn-rich supports decreased under reaction conditions resulting in higher Ni dispersion.