On-line monitoring of emulsion polymerisation by conductimetry and calorimetry

La concentration de tensioactifs dans les réactions de la polymérisation en émulsion agit directement sur le nombre et la stabilité de particules dans le latex. La mesure en ligne de cette concentration est alors primordiale pour comprendre le mécanisme de formation de ces particules ainsi que la cinétique de la réaction. Cette mesure est alors indispensable pour la supervision et la commande de ces procédés de polymérisation. L'objectif principal de cette étude est de démontrer la possibilité d'utiliser la méthode de conductimétrie pour estimer la concentration de tensioactifs dans le latex. L'influence de différents paramètres pouvant modifier le signal de conductimétrie durant les réactions de polymérisation en émulsion a été étudiée. Nous avons donc établi une relation liant la variation de concentration de tensioactifs à la surface totale de particules dans le latex. La conductimétrie peut également être combiner à la calorimétrie et aux observateurs d'états (les capteurs logiciels) pour estimer le nombre moyen et le diamètre de particules dans le latex. Pour réaliser cet objectif, nous avons utilisé des observateurs à grand gain qui sont bien adapté pour ce type de procédésLYON1-BU.Sciences (692662101) / SudocSudocFranceF

Performance of a novel green scale inhibitor

Many aspects of oilfield scale inhibition with green scale inhibi-tors (SIs) have remained untouched. For instance, the discharge of large amounts of produced water containing various types of hazardous chemi-cals, such as SIs into the environment has become a major concern. In-stead, environmental regulators encourage operators to look for greener SIs. In this study, the performance of a green SI was investigated using PHREEQC simulation. For a specific case study, two brines are considered to mix incompatibly to estimate the critical mixing ratio that has the high-est tendency to scaling. Subsequently, for 50/50 mixing ratio as the critical value, theoptimal dosage of SI and its performance in the presence of two different rocks were investigated such that 450 mg/L SI would be consi-dered as optimal value. Moreover, the simulated results show that more SI adsorption on calcite would be predicted, compared to dolomite

Study of Syngas Conversion to Light Olefins by Response Surface Methodology

The effect of adding MgO to a precipitated iron-cobalt-manganese based Fischer-Tropsch synthesis (FTS) catalyst was investigated via response surface methodology. The catalytic performance of the catalysts was examined in a fixed bed microreactor at a total pressure of 1–7 bar, temperature of 280–380°C, MgO content of 5–25% and using a syngas having a H2 to CO ratio equal to 2.The dependence of the activity and product distribution on MgO content, temperature, and pressure was successfully correlated via full quadratic second-order polynomial equations. The statistical analysis and response surface demonstrations indicated that MgO significantly influences the CO conversion and chain growth probability as well as ethane, propane, propylene, butylene selectivity, and alkene/alkane ratio. A strong interaction between variables was also evidenced in some cases. The decreasing effect of pressure on alkene to alkane ratio is investigated through olefin readsorption effects and CO hydrogenation kinetics. Finally, a multiobjective optimization procedure was employed to calculate the best amount of MgO content in different reactor conditions

LHHW/RSM reaction rate modeling for Co-Mn/SiO2 nanocatalyst in Fishcher-Tropsch synthesis

Abstract This study aims to assess the kinetics of Fischer–Tropsch (FT) reaction over the cobalt-manganese nanoparticles supported by silica oxide. Nanoparticles were synthesized by the thermal decomposition method using "[Co(NH3)4CO3]MnO4" complex and characterized by XRD, TEM, and BET techniques. The kinetics of the process were evaluated using a combination of Langmuir–Hinshelwood-Hougen-Watson (LHHW) and response surface methodology. Correlation factors of 0.9902 and 0.962 were obtained for the response surface method (RSM) and LHHW, respectively. The two methods were in good agreement, and the results showed that the rate-determining step was the reaction of the adsorbed methylene with the adsorbed hydrogen atom, and only carbon monoxide molecules were the most active species on the catalyst surface. A temperature of 502.53 K and a CO partial pressure of 2.76 bar are proposed as the optimal conditions by RSM analysis. The activation energy of CO consumption reaction was estimated to be 61.06 kJ/mol