Chemical Engineering & Technology

A microreactor setup with internal recirculation operated in continuous mode was used to demonstrate Beckmann rearrangement of cyclohexanone oxime dissolved in cyclooctane with oleum to ϵ-caprolactam. At 100 °C, the conversion of cyclohexanone oxime was complete; selectivity towards ϵ-caprolactam was 99 %. However, cyclooctane as solvent reduced the purity of the produced ϵ-caprolactam.

CaCO₃ particles can be synthesized by mixing CaCl₂-containing liposome suspension and CO₂-saturated water as demonstrated by scanning transmission electron microscopy and energy-dispersive X-ray spectroscopy. The liposomal reaction system can be applied to the formation of fine CaCO₃ particles through sequestration of CO₂ under optimized conditions.

For the first time it is demonstrated that the conventional dimethyl ether DME purification and methanol recovery distillation sequence can be effectively converted into a single-step separation based on the dividing-wall column (DWC) technology. The novel proposed DWC alternative decreases the energy requirements by 28 % and the equipment costs by 20 %.

Melt crystallization is a promising technology for the production of enriched unsaturated fatty acid mixtures from polysaturated and unsaturated fatty acid mixtures obtained by hydrolysis of natural plant oils. The effects of supercooling and cooling rates on deciding factors affecting crystallization were evaluated by high-resolution polarized-light microscopy.

Yarrowia lipolytica lipase was immobilized on economical bamboo charcoal to catalyze the resolution of the model enantiomers (R,S)-1-phenylethanol in heptane, exhibiting a significantly improved enzymatic catalysis in comparison to free lipase. In contrast to activated charcoal, on bamboo charcoal more lipase with high enzymatic efficiency can be immobilized.

Results of SO₂ absorption in a spray tower using hydrogen peroxide solutions are investigated. For comparison, a H₂O and NaOH solution was also used. A correlation is proposed, which shows the strong influence of the liquid flow rate. The results indicate that H₂O₂ is an important alternative for SO₂ removal in spray towers.

Equilibrium data for CO₂ and CH₄ adsorption on Cu-BTC powder and tablets were measured in the temperature range 308–373 K and 0–7 bar pressure and fitted with the Langmuir model. Also breakthrough experiments were performed in a fixed-bed filled with Cu-BTC tablets. Binary breakthrough curves confirmed that these tablets can be used for selective removal of CO₂ in natural gas processing.

A scale-down study of an industrial reactor for PVC production by means of emulsion polymerization is presented with the aim to identify the source of batch-to-batch variations in product quality. In Part 2 of this series of papers, the necessity of a large excess of base to control the particle size distribution of the seed process is demonstrated.

In order to find out the reasons for batch-to-batch variations in product quality, a scale-down study of an industrial reactor for PVC production by means of an emulsion polymeriza-tion process was performed. Parameters with the strongest influence on the quality of PVC were identified. An industrial recipe scaled down to a pilot reactor is presented.

The addition of a catalyst can improve the removal efficiencies for SO₂ and NO and lower the reaction temperatures. Optimum experimental parameters were determined. The characterization of activated carbon by X-ray diffraction confirmed that the main active component of the catalyst is CuO, which has different valences in the reductive atmosphere, resulting in high microwave absorption ability.

In Part 3 of a scale-down study on an industrial reactor for PVC production, the flow rate of initiator and second-stage surfactant proved to be the most important parameters for particle size distribution control. Changing the time point of injection of initiator and surfactant enables controlling the volume fractions of large and small particles.

To characterize the rheological properties and dispersion stability as well as the efficiency of a dispersion process in terms of stress frequency and intensity, a new dis-persing machine was developed. A theoretical process model was used to characterize the dispersion process in the dispermeter and in a dissolver. Moreover, this model was used to predict the dispersion results obtained in the dissolver.

Potential and limitations of the combination of in situ radio-frequency heating (ISRFH) and soil vapor extraction are exemplarily discussed for a demonstration project carried out at a former industrial site. Conditions restricting the extent of cleanup are discussed and conclusions for an efficient application of ISRFH in soil remediation are deduced.

Local mass transfer coefficients at each point over the dry surface in a symmetric mass transfer unit cell of corrugated-sheet structured packings were determined. Computational fluid dynamics simulation results with a Lam-Bremhorst low-Re-κ-ϵ turbulence model and a wall-surface reaction model corresponded well with previous experimental data.

The destabilization process of a commercial metal working fluid (MWF) emulsion artificially aged with CaCl₂ was characterized by UV-Vis-NIR spectroscopy. The wavelength exponent proved as a quantitative criterion in monitoring of the emulsion destabilization. This simple method can be applied to in situ characterization of MWF quality in machining processes.

Essential oils can be used as natural cattle growth promoters or biocides, but a formulation is required in order to protect the essential oil from evaporation and degradation, and to provide a controlled delivery. The encapsulation of lavandin essential oil in polycaprolactones by a particles from gas saturated solutions (PGSS) process is presented, analyzing the influence of process parameters on the morphology of particles and the efficiency of encapsulation.

The kinetics of the drying process of solid citrus wastes in a thin-layer fixed-bed dryer under different operational conditions is investigated. By means of artificial neural networks and four well-known drying kinetics correlations, the problem of selecting the best fit for solid waste moisture content as a function of time is addressed as well.

Nanocrystalline zeolite tetraethylammonium (TEA)-beta membranes were prepared by repeated coating of zeolite nanocrystals via hydrothermal crystallization from a colloidal solution over a porous stain-less-steel disc support. When the separation experiment was performed without applying any external pressure, a CO₂ selectivity over N₂ of 100 % could be achieved.

A fully automated and highly flexible ad- and desorption method for batch resin, solvent, and condition screening experiments was developed and implemented on a robotic platform, enabling the determination of essential process parameters without manual intervention. The hands-on time was significantly reduced, contributing to improved health and safety outcome for operators.

The internally heat-integrated distillation column (HIDiC) is considered as a promising option to improve significantly the energy efficiency of distillation columns. The effect of a higher stage number on operating cost and capital investment for an HIDiC was analyzed by two HIDiC design cases. Cost estimation parameters were defined by numerical simulation.

By the example of a severe explosion accident, the strong influence of the remaining hexane content on the flash point of crude olive pomace oil is evaluated. The oil changed from combustible to flammable and explosive oil as a result of the inefficiency of desolventization. Necessary actions are proposed to avoid the recurrence of similar events.

Phenylethenyl methyl carbonate was synthesized by the methoxycarbonylation of phenylacetaldehyde with dimethyl carbonate in the presence of solid base catalysts. Solid bases with moderate strength favored the formation of phenylethenyl methyl carbonate and the yield could be linearly correlated with the amount of moderate basic sites.

In the oil and natural gas industry, gas hydrates appear as a problem in drilling, production, and flow assurance processes. Dual effects of poly(ethylene oxide) (PEO), including inhibition and stabilization, on time-dependent isochoric methane hydrate formation are analyzed by kinetic measurements.

The feasibility of CO₂ capture in situ desulfurization using traditional desulfurizers was examined in Ca-based chemical looping combustion (CLC) of coal. The performances of CaSO₄ and desulfurizers were assessed under pressurized conditions in CLC of coal and the potential of anhydrite as a promising low-cost oxygen carrier was evaluated.

The reaction of petroleum coke with CuFe₂O₄ as oxygen carrier was systematically investigated. The evolution of minerals and sulfur species contained in the petroleum coke and their interactions with the reduced CuFe₂O₄ were explored in detail.

The mechanisms of the transformation from salt to free form drug during processing of a model drug are investigated with special emphasis on the interplay of salt solubility and pH of the excipients. The obtained results can provide a reliable guidance for selecting excipients for robust formulation design of solid dosage pharmaceuticals in salt forms.

A diffusion model-based approach is presented to model and optimize countercurrent Donnan dialysis. Integral transport coefficients were determined for several anions, with the objective to prepare task-specific ionic liquids (ILs) by continuous anion exchange. Anion conversions > 99 % were reached after model-based process optimization. Ultrapure IL were produced in long-term experiments for up to 130 h on stream.