Enhanced Simulated Moving Bed Reactor Process for Butyl Acrylate Synthesis: Process Analysis and Optimization

A novel process design based on the simulated moving bed technology for the synthesis of butyl acrylate (BAc) was investigated in order to get a more competitive industrial process. For that, a fixed-bed reactor was coupled with a simulated moving bed reactor. Reactive separation regions were determined for different conditions of process configurations and feed compositions allowing the optimal operating parameters to be found. Furthermore, the process integration was accomplished and the desorbent (<i>n</i>-butanol) recovery was also investigated ensuring the minimal BAc purity required (99.5% w/w). The viability and competitiveness of this process were evaluated after an economic analysis which showed that it required similar production costs and energy consumption as well for the highest production capacity when compared with other state-of-the-art processes for the BAc synthesis, presented so far

Performance Evaluation of Pervaporation Technology for Process Intensification of Butyl Acrylate Synthesis

Pervaporation-based hybrid processes have been investigated to overcome the drawbacks of equilibrium-limited reactions. Pervaporation processes are strongly recommended for heat-sensitive products and azeotropic mixtures as in the butyl acrylate system case, since pervaporation can operate at lower temperatures than distillation. In this work, experimental pervaporation data for multicomponent mixtures in the absence of reaction were measured for the compounds involved in the esterification reaction of acrylic acid with <i>n</i>-butanol at different temperatures: 323, 353, and 363 K. A commercial tubular microporous silica membrane from Pervatech was used which is highly selective to water, and its performance was evaluated by studying several parameters, like the selectivity, permeate fluxes, driving force of species, and separation factor. The effects of temperature and feed composition were assessed for binary, ternary, and quaternary mixtures. Increasing the temperature increases significantly the total permeate flux as well as the separation factor, which is higher for quaternary mixtures. The presence of butyl acrylate and acrylic acid reduces the total permeate flux since these molecules hinder the water permeation. The permeance of each species was correlated with temperature according to the Arrhenius equation, and a mathematical model was proposed to develop an integrated reaction–separation process using the experimental data obtained. The reaction conversion of the fixed-bed membrane reactor at steady state achieved 98.7% at isothermal conditions, increasing by 66% the conversion obtained in a fixed-bed reactor (at the same operating conditions)

Glycerol Valorization as Biofuel: Thermodynamic and Kinetic Study of the Acetalization of Glycerol with Acetaldehyde

The work reported in this article is a thermodynamic and kinetic study of the acetalization reaction between acetaldehyde and glycerol to produce glycerol ethyl acetal (GEA). A catalyst screening was performed allowing for the choice of Amberlyst-15 wet resin as the most suitable catalyst for this reaction. Through the study of the reaction thermodynamic equilibrium, it was possible to determine the value of the equilibrium constant as a function of temperature, ln­(<i>K</i>) = 1.419 + 1055/<i>T</i>, and the corresponding thermodynamic parameters Δ<i>H</i>_298 K⁰ = −8.77 kJ·mol^–1 and Δ<i>G</i>_298 K⁰ = −12.3 kJ·mol^–1. Additionally, the standard enthalpy and Gibbs free energy of formation of GEA were also obtained, as −584.4 and −387.0 kJ·mol^–1, respectively. The Langmuir–Hinshelwood–Hougen–Watson model considering internal mass-transfer limitations presented the best fitting of the reaction kinetic behavior. The parameters estimated for this model were <i>k</i>c (mol·g_cat^–1·s^–1) = 3.13 × 10⁹ – 6223/<i>T</i> and <i>K</i>_S,W = 1.82 × 10^–3 exp­(2361/<i>T</i>). The acetalization of glycerol with acetaldehyde presents an activation energy of 51.7 kJ·mol^–1

Propylene/Nitrogen Separation in a By-Stream of the Polypropylene Production: From Pilot Test and Model Validation to Industrial Scale Process Design and Optimization

Two industrial-scale pressure swing adsorption (PSA) processes were designed and optimized by simulations: recovery of only nitrogen and recovery of both nitrogen and propylene from a polypropylene manufacture purge gas stream. MIL-100­(Fe) granulates were used as adsorbent. The mathematical model employed in the simulations was verified by a PSA experiment. The effect of several operating parameters on the performance of the proposed PSA processes was investigated. For the nitrogen recovery, a 5-step 2-column PSA process produced a nitrogen stream of 95.4% purity with recovery of 85.2%, productivity of 6.0 mol N₂/kg adsorbent/h, and power consumption of 156 Wh/kgN₂. Nitrogen and propylene with 96.2% and 97.6% purity, respectively, were obtained from the 6-step 3-column nitrogen and propylene recovery PSA process. The nitrogen and propylene recoveries obtained are 98.4% and 91.0%, respectively. The nitrogen and propylene productivities were estimated as 4.61 and 1.83 mol product/kg adsorbent/h and the power consumption as 383 Wh/kgN₂

Syngas Purification by Porous Amino-Functionalized Titanium Terephthalate MIL-125

The adsorption equilibrium of carbon dioxide (CO₂), carbon monoxide (CO), nitrogen (N₂), methane (CH₄), and hydrogen (H₂) was studied at 303, 323, and 343 K and pressures up to 7 bar in titanium-based metal–organic framework (MOF) granulates, amino-functionalized titanium terephthalate MIL-125­(Ti)_NH₂. The affinity of the different adsorbates toward the adsorbent presented the following order: CO₂ > CH₄ > CO > N₂ > H₂, from the most adsorbed to the least adsorbed component. Subsequently, adsorption kinetics and multicomponent adsorption equilibrium were studied by means of single, binary, and ternary breakthrough curves at 323 K and 4.5 bar with different feed mixtures. Both studies are complementary and aim the syngas purification for two different applications, hydrogen production and H₂/CO composition adjustment, to be used as feed in the Fischer–Tropsch processes. The isosteric heats were calculated from the adsorption equilibrium isotherms and are 21.9 kJ mol^–1 for CO₂, 14.6 kJ mol^–1 for CH₄, 13.4 kJ mol^–1 for CO, and 11.7 kJ mol^–1 for N₂. In the overall pressure and temperature range, the adsorption equilibrium isotherms were well-regressed against the Langmuir model. The multicomponent breakthrough experimental results allowed for validation of the adsorption equilibrium predicted by the multicomponent extension of the Langmuir isotherm and validation of the fixed-bed mathematical model. To conclude, two pressure swing adsorption (PSA) cycles were designed and performed experimentally, one for hydrogen purification from a 30/70% CO₂/H₂ mixture (hydrogen purity was 100% with a recovery of 23.5%) and a second PSA cycle to obtain a light product with a H₂/CO ratio between 2.2 and 2.4 to feed to Fischer–Tropsch processes. The experimental cycle produced a light stream with a H₂/CO ratio of 2.3 and a CO₂-enriched stream with 86.6% purity as a heavy product. The CO₂ recovery was 93.5%

Toward Understanding the Influence of Ethylbenzene in <i>p</i>-Xylene Selectivity of the Porous Titanium Amino Terephthalate MIL-125(Ti): Adsorption Equilibrium and Separation of Xylene Isomers

The potential of the porous crystalline titanium dicarboxylate MIL-125­(Ti) in powder form was studied for the separation in liquid phase of xylene isomers and ethylbenzene (MIL stands for Materials from Institut Lavoisier). We report here a detailed experimental study consisting of binary and multi-component adsorption equilibrium of xylene isomers in MIL-125­(Ti) powder at low (≤0.8 M) and bulk (≥0.8 M) concentrations. A series of multi-component breakthrough experiments was first performed using <i>n</i>-heptane as the eluent at 313 K, and the obtained selectivities were compared, followed by binary breakthrough experiments to determine the adsorption isotherms at 313 K, using <i>n</i>-heptane as the eluent. MIL-125­(Ti) is a <i>para</i>-selective material suitable at low concentrations to separate <i>p</i>-xylene from the other xylene isomers. Pulse experiments indicate a separation factor of 1.3 for <i>p</i>-xylene over <i>o</i>-xylene and <i>m</i>-xylene, while breakthrough experiments using a diluted ternary mixture lead to selectivity values of 1.5 and 1.6 for <i>p</i>-xylene over <i>m</i>-xylene and <i>o</i>-xylene, respectively. Introduction of ethylbenzene in the mixture results however in a decrease of the selectivity