Intensification of an Irreversible Process using Reactive Distillation– Feasibility Studies by Residue Curve Mapping

Reactive distillation processes are very promising in substituting Sconventional liquid phase reaction processes. However this technology is not suitable for all kind of processes or types of reaction. Therefore, assessing the feasibility of these process concepts forms an important area in current and future research and development activities. The present paper focuses on the feasibility studies based on the construction of residue curve maps for the toluene methylation system. The RCMs were constructed and analyzed; it is concluded that the process of synthesis of xylenes when carried out in the reactive distillation column enhances the selectivity of the desired para isomer. Keywords: Reactive Distillation, Residue Curve Maps, Feasibility Study, Toluene Methylation, Aspen Plus

THE INFLUENCING FACTORS OF SO42- AND NO3- IN PM10 IN JINHUA, CHINA

Sulfate (SO42-) and nitrate (NO3-) are the main secondary inorganic components in atmospheric particulates. It is of great significance to understand the formation and evolution of air pollution in the process of air pollution. In this study, samples of PM10 were collected in Jinhua City in eastern China from December 2019 to January 2020 and from June 2020 to August 2020, and also analyzed the influence of different meteorological conditions and gaseous pollutants on the formation of SO42- and NO3- in PM10. The results show that high relative humidity has a significant effect on the increase of sulfur oxidation rate (SOR) in winter, indicating that the winter liquid phase reaction is more conducive to the formation of SO42-. SOR and nitrogen oxidation rate (NOR) decrease with increasing temperature in winter, and increase with increasing temperature in summer. The light intensity has an important promoting effect on both SOR and NOR, indicating that the photochemical reaction is beneficial to the formation of SO42- and NO3-. Both the gaseous precursors SO2 and NO2 have significant promoting effects on the formation of SO42- and NO3- in winter, and the promoting effect of O3 on NOR is higher than that on SOR, indicating that atmospheric oxidation capacity has a greater effect on the formation of NO3-, and the effect of CO on SOR is higher than that on NOR, and there is a negative correlation with SOR.

NMR Spectroscopic Method for Studying Homogenous Liquid Phase Reaction Kinetics in Systems used in Reactive Gas Absorption and Application to Monoethanolamine-water-carbon Dioxide

An NMR spectroscopic method for measuring homogenous liquid phase reaction kinetics in systems that are used in reactive gas absorption processes is presented. In the kinetic experiment, carbon dioxide loaded and unloaded aqueous amine solutions are mixed such that no gas phase is involved. This procedure enables studying liquid phase reaction kinetics without the influence of the kinetics of the physical absorption process. A rapid-mixing NMR flow cell is used for the measurements, which are carried out in stopped-flow mode. 1H NMR spectra are taken at short intervals to monitor the kinetic process. The cell is liquid thermostatted and pressure resistant, such that a wide range of conditions can be studied. The new method was used for studying reaction kinetics in the system monoethanolamine (MEA)–water (H2O)–carbon dioxide (CO2) at temperatures between 293 and 333 K. From the data, information on the kinetics of the reaction of MEA with bicarbonate (HCO3-) to form MEA carbamate was obtained. That reaction was investigated for the first time in the present work without using bicarbonate salts. An Arrhenius model was fitted to the new data. The formation of MEA carbamate from MEA and HCO3- is often neglected in models for describing the reactive absorption of CO2 with aqueous MEA solutions. A process simulation study carried out in the present work reveals that it should be taken into account in predictions of reactive absorption processes that are operated under elevated pressure with a high mole fraction of CO2 in the gaseous phase.

Turnover Rate of Metal-Catalyzed Hydroconversion of 2,5-Dimethylfuran: Gas-Phase Versus Liquid-Phase

Hydroconversion (hydrogenation and hydrogenolysis) of biomass-derived furanic compounds giving furan ring-hydrogenation and ring-cleavage products attracts interest for sustainable production of chemicals and fuels. Here, the hydroconversion of 2,5-dimethylfuran (DMF), chosen as a model furanic compound, was investigated at a gas-solid interface over carbon-supported Pt, Pd, Rh and Ru metal catalysts in a fixed-bed reactor at 70–90 °C and ambient pressure. Pt/C was mainly active in ring cleavage of DMF to produce 2-hexanone as the primary product, followed by its hydrogenation to 2-hexanol and hexane. In contrast, Pd/C, Rh/C and Ru/C selectively hydrogenated the furan ring to 2,5-dimethyltetrahydrofuran (DMTHF). The turnover frequency (TOF) of metal sites in the gas-phase DMF hydroconversion was determined from zero-order kinetics in the absence of diffusion limitations. The TOF values decreased in the sequence Pt > Rh > Pd >> Ru, similar to the liquid-phase reaction. The TOF values for the gas-phase reaction were found to be one order of magnitude greater than those for the liquid-phase reaction. This indicates that the gas-phase process is potentially more efficient than the liquid-phase process. TOF values for hydroconversion of ring-saturated furan derivatives, tetrahydrofuran and DMTHF, on Pt/C, were much lower than those for DMF.