Industrial & Engineering Chemistry Research最新文献

The aim of our present work is to synthesize a comb-like polymeric pour point depressant (PPD), poly(octadecyl methacrylate) (POMA), using a reversible addition–fragmentation chain transfer (RAFT) polymerization technique, to improve the flowability of waxy crude oil. Analytical techniques such as FT-IR and NMR spectroscopy confirm the formation of POMA, while the molecular weights (MWs) were determined using the size exclusion chromatography (SEC) technique. Furthermore, viscosity and gelation point measurements were employed rheometrically to evaluate the efficiency of the synthesized polymer as a flow improver for waxy crude. The SEC results show that the number-average molecular weight (M_n) of the synthesized POMA increases linearly with conversion. The RAFT polymerization produces polymers with very narrow molecular weight distributions (MWDs) (1.19–1.35) as compared to that in conventional radical polymerization (MWD > 2). Under optimum conditions, the prepared polymer, POMA, reduced the gelation point of the crude oil by 4.1 °C at a 2000 ppm concentration. Furthermore, at a 2000 ppm concentration, the apparent viscosity of the crude oil is decreased from 379.71 mPa·s to 70.67 mPa·s at a temperature of 0 °C. Thus, the reduction in the apparent viscosity and gelation point signifies that the synthesized POMA acts as an effective polymeric additive for crude oil at low temperature.

The recycling of waste poly(ethylene terephthalate) (PET) is of great significance to alleviate environmental pollution and resource depletion. The metal-based catalysts currently used in chemical recycling often lead to metal residues and product coloration, which limits the industrialization of PET recycling. In this context, tetrabutylcarboxylate phosphate as an environmentally friendly ionic liquid catalyst containing organophosphorus was synthesized, and optimal reaction conditions for the glycolysis of PET were investigated, enabling 100% PET conversion and 40.8% bis(2-hydroxyethyl) terephthalate (BHET) yields at 200 °C and 120 min. FT-IR, ¹H NMR, and XRD showed that the glycolysis products were mainly composed of BHET and a spot of dimers. The ¹H NMR spectrum showed that the reaction model of PET glycolysis catalyzed by an ionic liquid is a shrink-core model, and the apparent activation energy is 89.73 kJ/mol. A possible reaction pathway was proposed subsequently. The prepared green and efficient ionic liquid is expected to replace the traditional metal salt catalyst that leaves contaminants in the product for the recovery of waste polyester products.

Manufacturing chemical products that meet marketing and regulatory demands is critical in batch processes. This is accomplished by creating well-designed input profiles based on process knowledge or historical data. Over the years, many data-driven product design methods have been developed, including latent variable model inversion, which is known for its convenience and efficiency and has been extensively applied to various batch systems. However, even with well-designed input conditions that meet quality requirements, products may still fall short due to the inevitable model mismatch or unmeasurable process disturbances. To address this issue and improve the quality control performance in batch processes, this work proposes an approach that combines iterative learning and latent variable model inversion (IL-LVMI). The latent variable model captures the correlation between input profiles and quality attributes, and model inversion obtains a design space containing a set of input profiles that satisfy the product specifications. The designed input profiles are then reconstructed and implemented in the target batch processes. To increase the accuracy of the obtained product quality, the employed iterative learning algorithm minimizes the deviation between the actual output and the requirements for each iteration. A null space can exist to calculate input increments, and input profiles can be arbitrarily adjusted along the direction of the null space without affecting the convergence performance. By using IL-LVMI, we obtain not only satisfactory product quality but also an updated design space. The methodology proposed in this study was validated through four scenarios by using a continuous stirred tank reactor. The product design results were promising, and an updated design space was visualized by the proposed IL-LVMI approach.

One of the environmental concerns in the chemical industry is using organic solvents that are not environmentally friendly. Eutectic mixtures, also called deep eutectic solvents (DESs), have emerged as their substitutes due to favorable properties, including biodegradability, tunability, and low cost, among others. DESs show applications in extractions, biocatalysis, etc. To expand their uses, it is crucial to characterize their properties and understand their interactions with other solvents. In this study, the surface tension of DESs between 30 and 60 °C at 101.3 kPa was measured. The DESs were prepared using choline chloride or betaine as the hydrogen bond acceptor (HBA) and a glycol (ethylene glycol, 1,2-propanediol, 1,3-propanediol, or 1,4-butanediol) as the hydrogen bond donor (HBD) in different molar ratios. The surface tension of DESs + water mixtures was measured over the entire range of compositions. To assess the effect of temperature, HBD chain length, and water content, PC-SAFT coupled with the density gradient theory was used to model the surface tension. Furthermore, molecular dynamics simulations were conducted to gain a molecular understanding of the components at the interface. The molecular insights obtained from these simulations and the experimental data can help reduce the number of experiments when designing DESs for chemical processes.

The shape memory polymers (SMPs) are intelligent and adaptive materials that can undergo shape recovery in response to external stimuli. The combination of functionality, adjustable properties, and renewability has endowed SMPs with burgeoning interest. The biobased and biodegradable SMPs were successfully prepared by incorporating natural Eucommia ulmoides gum (EUG) and polycaprolactone (PCL) as the constituents through dynamic vulcanization. The fine phase morphology of EUG/PCL SMPs was achieved through complete phase inversion and the establishment of good interfacial compatibility between the PCL and EUG phases, which positively influenced their mechanical and shape memory properties. The EUG/PCL SMPs demonstrated exceptional shape recovery properties, with a remarkable 97% shape recovery and 99% shape fixity. Moreover, the EUG/PCL SMPs also exhibited remarkable reprocessability, and the reprocessed EUG/PCL SMPs still showcased exceptional shape memory properties. The crystalline EUG functioned synergistically as a fixed phase alongside PCL, thereby effectively stabilizing the deformed shape. Specifically, the cross-linked and elastic EUG particles dispersed in PCL provided sufficient restoring force to drive the PCL molecular chains to recover their initial shape.

Achieving excellent conversion and high stability is crucial in promoting practical applications of many emerging oxidative desulfurization (ODS) catalysts. Herein, POM@HUSYs were prepared through an in situ procedure, which enhanced the dispersion of polyoxometalate (POM) and reduced the leaching of active components. The catalyst was prepared in an acidic environment, which served a dual purpose. One purpose was to introduce Lewis acid sites in the zeolite, while the other was to synthesize the corresponding POM to provide Bro̷nsted acid sites. By adjusting the synthesis conditions, catalysts with the best synergistic impact between the Lewis and Bro̷nsted acid sites were discovered. The best sample HPW@HUSY_24H-0.06M could achieve 99.2% DBT conversion in 120 min. Additionally, the obtained catalyst could efficiently adsorb the ODS products from the oil phase without extraction. The concept of a synergistic catalytic mechanism guides the future design and development of heterogeneous catalysts for ODS reactions.

Five amine-diamide ligands (DAMIA) with varying alkyl chain lengths and steric hindrances are developed for selective extraction of Am³⁺ over Eu³⁺ in high-acidity HNO₃ solution with the aim of understanding the structure–activity relationship. The ability of these ligands to extract metal ions is closely related to their basicity. The weaker the basicity is, the stronger the extraction ability is. The substituent on the aminic N has more significant effect on the extraction ability than that on the amidic N. Among the five ligands, the DAMIA containing five branched 2-ethylhexyl substituents demonstrates the highest extraction ability and selectivity at molar acidity level. Slope analysis suggests the formation of a 1:1 metal/ligand extracted species, which is also supported by the results obtained from the UV–vis spectrophotometric titration. Furthermore, the analyses of Fourier transform infrared (FT-IR), time-resolved laser-induced fluorescence spectroscopy (TRLFS), and X-ray photoelectron spectroscopy (XPS) for the extracted complex indicate that one Eu³⁺ ion may be nine-coordinated by one ligand molecule in a tridentate manner via two amide O atoms and one tertiary amine N atom and three bidentate NO₃^– ions. There is no H₂O molecule in the inner coordination sphere of central Eu³⁺. Additionally, based on the studies of solvent extraction and complexation, the extraction of metal ions follows the neutral complexation extraction model, and the corresponding thermodynamic parameters (ΔH, ΔS, and ΔG) are also presented.

The mass transfer between CO₂ and crude oil is crucial for CO₂-EOR. However, traditional methods are complex and time-consuming, leading to slow progress in the study of the mass transfer between CO₂ and crude oil. This study employed microfluidic technology to generate gas–liquid slug flow for rapid investigation of the mass transfer process between CO₂ and crude oil within ∼30 s. A method was developed to eliminate the pressure drop term, suitable for mass transfer studies in gas–liquid systems where the liquid phase’s high viscosity led to a high-pressure drop. This study systematically investigated the effects of gas and liquid flow rates, temperature, and the type and concentration of surfactants on the liquid-side volumetric mass transfer coefficients of CO₂ and crude oil. These methods enable a rapid assessment of the influence of factors on other gas–liquid mass transfer systems and provide a data foundation for reactor design and optimization.

Treatment of municipal wastewater (MWW) is one of the potential challenges in developing/underdeveloping countries. The present work demonstrates treatment of MWW using the irradiation effect of ultrasound (US) and light-emitting diode ultraviolet (UVC). The process was further intensified using the combined effect of irradiation with H₂O₂/O₃. MWW consisted of elevated pathogen concentrations of Enterobacter aerogenes, Escherichia coli, and other coliforms with a total coliform concentration of 12 × 10³ CFU/mL. The efficiency of processes was analyzed on complete inactivation of total coliform, pseudo-first-order kinetic rate constant, synergy analysis, COD removal, and process economics. Nearly complete elimination of pathogen was observed for the US+UVC effect in 20 min, whereas 83 and 98.6% of removal were observed for US and UVC effects, respectively. Further combination of US and UVC with H₂O₂ showed an enhanced inactivation rate for total coliforms. The least treatment time of 10 min was required for US–UVC–H₂O₂ for complete inactivation with a pseudo-first-order kinetic rate constant of 3.56 ± 0.3 min^–1. The synergy coefficient for UVC–H₂O₂ (1.9) was much higher as compared with other effects. The operational cost for the UVC–H₂O₂ process was 12.6 times higher than that for the UVC–O₃ process, with a synergy coefficient of 1.1. Synergy of US/UVC with H₂O₂/O₃ reduced the initial oxidant requirement. It was reduced by 50% compared to nonsynergy studies. Based on process analysis, UVC–O₃ was observed as the most suitable combination for the inactivation of pathogens present in MWW with a COD removal of 91.1% and an operational cost of 0.3$/m³. The synergy of UVC–O₃ has potential beneficial effects to overcome the limitation of individual processes and development of large-scale processes.