A new strategy for enhancing the hydrazine structure based on the inductive effect and conjugation effect of strong electron-withdrawing groups has been designed to effectively absorb CO2 with hydrazide-based ionic liquids (ILs). All three ILs aqueous solutions (diethylenetriamine oxalyl dihydrazide [DETAH]2[ODH], diethylenetriamine propanedioyl dihydrazide [DETAH]2[PDH], and diethylenetriamine succinic dihydrazide [DETAH]2[SDH]) exhibit good absorption performance. Through a combination of absorption-desorption experiments, FT-IR and NMR characterizations, and density functional theory (DFT) calculations, the results indicate that the unique structure of anions enables physical adsorption to occur again after chemically absorbing CO2. The special absorption process is responsible for the unusual regeneration properties. Hopefully, the results of this work are helpful in providing a new method for designing highly efficient gas absorbents.

Abstract Conventional H4PMo11VO40 (HPAV) catalysts for the selective oxidation of methacrolein (MAL) to methacrylic acid (MAA) are limited by insufficient active-site accessibility and poor mass transport. Herein, hollow porous core–shell UF-CsPAV catalysts were prepared using SiO2 microspheres, PEO–PS copolymer, and urea-formaldehyde (UF) resin as a dual-template/organic precursor system. The optimized catalyst exhibited a specific surface area of 438.0 m2· g–1 and well-developed mesoporous channels. During calcination, NH4+ species generated from the UF resin regulated the heteropolyacid environment, increasing acidity, the V4+/V5+ ratio, and terminal oxygen species. At 335 °C and a space velocity of 1020 h–1, the catalyst prepared with 1 μm SiO2 microspheres and 50 wt % CsPAV achieved 88.1% MAL conversion, 91.2% MAA selectivity, and MAA space-time yield (STY) of 1.54 mmol·cm–3·h–1 over 100 h. This work demonstrates an integrated strategy for coupling porous-architecture control with acid-redox regulation in MAL oxidation.

The catalytic efficiency for methyl methacrylate (MMA) production via aldol condensation of methyl propionate (MP) and formaldehyde (FA) depends on the acid-base and structural properties of the catalyst. Inspired by this, a synergistic design strategy is implemented by fabricating Cs/Al-MCM-41 catalysts, where Al doping preserves ordered mesopores and tunes acid-base properties. This approach generates an optimal density of medium acid sites together with a balanced distribution of weak-to-medium base sites, leading to 90% MMA selectivity and a space-time yield of 0.29 g/(gcat & centerdot;h). Moreover, the mesoporous confinement not only enhances the dispersion of Cs active species but also suppresses the condensation of coke precursors, thereby significantly improving the catalyst stability. Density functional theory (DFT) calculations reveal that basic Cs-O-Si sites and acidic Al sites cooperatively activate MP and FA, promoting aldol condensation. This work demonstrates that the integration of targeted acid-base regulation with structural confinement provides a rational catalyst design principle for efficient aldol condensation.

Propylene hydroformylation is a typical large-scale gas-liquid reaction. Nevertheless, exorbitant costs and theoretical studies lagging far behind practical industry have prevented advancements in reactor efficiency. In this work, the flow, mass transfer, and reaction processes within the gas-liquid reactor were simulated using a three-dimensional CFD-PBM coupled model. The coupling processes between the flow field, mass transfer, and reaction in the gas-liquid reactor are clarified in this study. It provides precise direction for further process optimization by introducing the Hatta number as a quantitative criterion to determine the reaction's controlling step (mass transfer-controlled or reaction-controlled). The constraints of conventional single-point analysis were overcome by visualizing a Ha number distribution contour, which showed that about 65% of the volume inside the propylene hydroformylation reactor is in a mass transfer-limited state. Based on this, operational parameter optimization was carried out, and the findings show that reaction efficiency may be successfully increased by reasonably raising the superficial gas velocity and system pressure within a certain range. The conversion rate increased by 23% when the superficial gas velocity doubled and by two times when the pressure doubled. Additionally, the effects of the stirring device and rotational speed were investigated, resulting in a 19% increase in conversion rate after optimization. The design and process optimization of similar hydroformylation gas-liquid reactors can benefit from this research.

This work proposes a carbon interface engineering strategy for developing high-performance Cs/Al-MCM-41@C catalysts toward methyl methacrylate (MMA) synthesis. An amorphous carbon layer with abundant defects was constructed as a multifunctional modifier. It served as an electronic modulator to enhance the intrinsic activity of Cs-O species and framework Al sites, while simultaneously acting as an acid-base promoter. Specially, it passivated strong acid sites and introduced complementary acid-base functionalities, enhancing their synergistic effect. Additionally, the carbon coating reduced surface hydrophilicity, thereby effectively inhibiting the side reaction of ester hydrolysis. These effects collectively boosted the catalytic performance: the improvement in methyl propionate (MP) conversion was primarily driven by an increase of weak-to-medium base sites, while enhanced MMA selectivity resulted from the optimization of medium acid sites and inhibited side reactions. The optimal catalyst achieved 25.3% MP conversion, 92.8% MMA selectivity, and a space-time yield (STY) of 0.38 g/ (gcat & sdot;h), along with excellent stability over 200 h due to suppressed coking and maintained structural integrity. Herein, interfacial carbon engineering was proposed as a design principle for balancing active-site cooperation in aldol condensation catalysts.

The development of efficient and eco-friendly catalysts for the conversion of CO2 and propylene oxide (PO) to propylene carbonate (PC) is vital for carbon-neutral goals. To overcome the corrosion and environmental issues of halogenated ionic liquids (ILs), two novel halogen-free ILs were designed by pairing a p-toluenesulfonate anion with a carboxyl- or ether-functionalized 1-butyl-3-methylimidazolium cation. The carboxyl-functionalized IL, [HCPMIM][p-TSA], showed superior performance, achieving 98.60% PO conversion and 98.21% PC selectivity. Density functional theory (DFT) calculations confirmed its strong hydrogen-bond-donating ability, which led to the lowest energy barrier in the rate-determining step, consistent with the experimental data. This study provides a theoretical basis for designing efficient halogen-free catalysts and elucidates the reaction mechanisms.

Polycarbonate is a widely used engineering plastic. However, synthesis procedures using phosgene produce toxic gases that cause environmental pollution. It is important to improve the performance of polycarbonate by using a green and safe process. Here, we synthesized tetramethylbisphenol A and bisphenol A copolymers by a green, nonphotogas melt-transesterification process using bisphenol A, diphenyl carbonate, and tetramethylbisphenol A as reaction materials. The catalysts required for the synthesis were screened. The chemical structures of the polymerization products were confirmed by an infrared spectrometer and a nuclear magnetic resonance spectrometer. The thermal and mechanical properties of polycarbonate materials were measured through differential scanning calorimetry, thermogravimetry, and an electronic Universal Testing Machine. The results showed that tetramethylbisphenol A copolycarbonate was successfully synthesized by a melt-transesterification process. Moreover, the addition of tetramethylbisphenol A significantly improved the thermal and mechanical properties of polycarbonate. The effects of catalyst dosage, diphenyl carbonate/diphenol molar ratio, polycondensation reaction temperature, and time on the molecular weight of tetramethylbisphenol A and bisphenol A copolymer were investigated, and the optimal conditions were obtained.

Methoxycarbonylation of ethylene catalyzed by palladium complexes with bulk steric bidentate phosphine ligands has always been a significant research topic, however, the mechanism by which ligands regulate the active center of catalysts and affect the catalytic reactive remains inadequately investigated. Here, the structure-activity relationship of the palladium hydric complex ([LPdH]+) active species with a new large steric bidentate phosphine ligand(1,2-bis((tert-butyl(pyridin-2-yl) phosphanyl)methyl) benzene)(L2) was studied using the density functional theory(DFT) and wave function analysis methods. It was found that the “donor-acceptor” interaction was the essence of the microelectronic structure environment regulation of the central metal by ligands. Catalytic activity differs with the d-band center of catalyst center metal Pd which is related to the configuration and the ligands of the catalyst active species. The d-band center of the central metal is closer to the Fermi level, the rate-controlled step energy barrier is lower, and the activity is higher. The activity order of the three catalyst complexes with different ligands ((1,2-Bis(di-tert-butyl phosphinomethyl)benzene (L1), L2 and (1,10-bis(tert-butyl(pyridin-2-yl)phosphanyl) ferrocene (L3) was predicted as: [L3PdH]+>[L2PdH]+>[L1PdH]+. A new hypothesis of d-orbital vacancy induced cross-cycling mechanism which has not been involved during the traditional cognition for ethylene methoxycarbonylation was proposed. This work elucidates the regulatory strategy of ligands on catalysts systematically and suggests a reaction mechanism from a new perspective, which is instructive for the design and application catalysts for ethylene methoxycarbonylation reactions.

To solve the problems of small specific surface area and poor thermal stability of CsH3PMo11VO40 (CsPMo11V) catalyst, it was proposed that the organic ammonium precursor polydopamine (PDA) was coated on SiO2 to form PDA-coated SiO2 carrier (SiO2@PDA) and then CsPMo11V was supported to form SiO2@PDA-CsPMo11V supported catalyst. In this work, the structure-oriented effect of dopamine layer between carrier and active component on NH4+ distribution was focused on. The performance of the SiO2@PDA-CsPMo11V catalyst was evaluated by methacrolein (MAL) oxidation. At the optimum loading of 50 wt%, the conversion of MAL and the selectivity to methacrylic acid (MAA) reached 81.9% and 89.1%, respectively. After continuous evaluation for 120 h, the catalyst exhibited good stability. The reaction kinetic modeling with the Mars-van Krevelen mechanism for the supported catalyst was conducted, which included the oxidation of MAL to MAA on the catalyst and the re-oxidation of the reduced catalyst, and the results suggested that the re-oxidation reaction of the catalyst was the rate-determining step.

Converting CO2 into valuable chemicals is an effective way to alleviate the high level of global CO2. The cycloaddition reaction of CO2 and propylene oxide (PO) has atomic economy and has the advantage of environmental friendliness compared with the traditional phosgene method of propylene carbonate (PC). Due to the chemical inertness of CO2, catalysts are needed to make the reaction proceed smoothly. Through rational design, a multifunctional catalyst that combines the activation sites and attack sites of PO and the adsorption sites of CO2 can be formed. At the same time, the use of harmful substances can be reduced by catalyst design, making the catalytic process more environmentally friendly. In this work, we discuss the research progress of the synthesis of PC from CO2 and PO. Starting from the reaction mechanism, the catalytic system of the reaction is summarized from the perspective of catalyst design. In homogeneous catalysts, the focus is on the effect of catalyst composition on catalytic performance. In heterogeneous catalysts, the focus is on the process of heterogenization (preparation methods), including supported, confined, and polymerized heterogeneous catalysts. In addition, the promising photocatalysis and biomass catalysis are especially introduced. Finally, in order to make the experimental results move toward industrial production, several problems existing in the industrialization are discussed, including production equipment, the influence of the CO2 source, and product/catalyst separation.

Di(2-ethylhexyl)-1,2-cyclohexane dicarboxylate (DEHCH) is expected to function as a non-toxic plasticizer for replacing di(2-ethylhexyl) phthalate (DEHP). During the esterification for synthesis of DEHCH, the di-esterification process is usually known as rate control step. To better understand this process, Density Functional Theory (DFT) was utilized to investigate the mechanism of mono(2-ethylhexyl)-1,2-cyclohexane dicarboxylate with 2-ethylhexanol catalyzed by tetraisopropyl titanate [Ti(OiPr)(4)], MIL-125, MIL-125-NH2, and hydrated MIL-125. The results indicate that Ti(OiPr)(4) possesses a single coordinatively unsaturated Ti site and the reaction follows the bimolecular nucleophilic substitution (SN2) mechanism, with an energy barrier as high as 184.97 kJmol(-1). Given Ti's high oxygen affinity and the abundance of reaction sites in metal-organic frameworks (MOFs), MIL-125, was innovatively selected for investigation. Simulated results show that the mu(2)-O bridging between the two coordinatively unsaturated Ti atoms acts as an additional Br & oslash;nsted base site, enhancing the reactivity. Meanwhile, the generated mu(2)-OH assists in dehydration, serving as the rate-determining step with an energy barrier of 101.11 kJmol(-1). To further improve the dehydration, the -NH2 group functionalized on the organic ligand and the dissociated -OH group from product water were strategically utilized as distinct Br & oslash;nsted base sites. In MIL-125-NH2, the energy barrier for dehydration was reduced to 33.31 kJmol(-1). Notably, in hydrated MIL-125, 2-ethylhexanol remains unadsorbed, lowering the energy barrier for dehydration to 25.24 kJmol(-1). These findings suggest that MIL-125 can transform the adverse impact of product water into a beneficial factor, thereby MIL-125 is recommended to catalyze the esterification of 1,2-cyclohexanedicarboxylic acid with 2-ethylhexanol.

An efficient method for prediction in the capture of CO2 by ionic liquids (ILs) was reported. Quantum chemistry (QC), molecular dynamics (MD), and kinetic Monte Carlo (KMC) methods were combined to develop a new model and method for investigating the CO2 absorption mechanism and predicting the CO2 chemical absorption by nine kinds of ILs. Then, three kinds of ILs with excellent structures were chosen and prepared to investigate their behavior of CO2 absorption, desorption, and regeneration capabilities. The results indicated that the mean error between the new prediction model and the experimental values is 5.26 %. Finally, an ideal IL (Diethylenetriamine 2-Imidazolidinone ([DETAH]2[MI]) for the capture of CO2 was obtained through design, model prediction, and experimental verification. It showed a high available absorption capacity of 3.69 mol CO2/mol ILs and excellent reversibility. It can be seen that the model and methods established in this work accurately predicted the absorption capacity of ILs involved in chemical reactions for the first time, and we hope that it can be used as an effective way to quickly screen ILs.

The fluorine-containing compound with symmetrical structure (I-C2H4-(CF2)n-C2H4-I) is a widely used the intermediate of fluorine-containing copolymer having various applications in the organic fluorine chemical industry. Herein, the addition reaction of 1,6-diiodoperfluorohexane (I-C6F12-I) with ethylene was studied at different temperatures (130 to 170 degrees C), reaction time (4 to 12 h), solvents (acetonitrile, DMF, Py, n-hexane) and initiators (AIBN, DTBP, CuI, CuCl). The yield of the product (I-C2H4-C6F12-C2H4-I) was up to 73 % under optimal reaction conditions (150 degrees C, 10 h, CuI, acetonitrile). The kinetic equation of the reaction was derived through further studies on the reaction kinetics. The addition reaction is a consecutive reaction, the reaction order and the activation energy of the first step (I-C6F12-I to I-C6F12-C2H4-I) are 1.131 and 56.53 kJ mol-1, and the reaction order and the activation energy of the second step (I-C6F12-C2H4-I to I-C2H4-C6F12-C2H4-I) are 0.479 and 49.81 kJ mol-1. These are important results that allows for further process intensification and designing of reactor.

Methyl methacrylate (MMA) is a significant chemical raw material with various applications. The main industrial production processes are the acetone cyanohydrin (ACH) process and the isobutene process. The former suffers from toxic feedstocks, while the latter highly depends on oil. A viable alternative is using low-toxicity and abundant ethylene or methyl acetate as a raw material. This review examines the development of catalysts in the ethylene (C2) and methyl acetate processes. In these green processes, aldol condensation is a key reaction, which is crucial in organic synthesis for the formation of C-C bonds in carbonyl compounds. However, there is currently no research that systematically reports on the catalysts used in aldol condensation within these processes. Here, we discuss the catalytic mechanism of aldol condensation. Furthermore, the effects of key factors on the acid/ base catalysts used in aldol condensation are systematically elucidated, including acid-base cooperative interactions, structural integrity, and active sites distribution. Additionally, the methods that enhance catalytic activity and stability through modification are discussed. We aim to propose a comprehensive paradigm for the rational design and optimization toward sustainable catalytic systems.

Viscosity and absorption capacity are the main indexes to evaluate functionalized ionic liquids. Based on the precise design strategy of both anion and cation absorption, a dual-functionalized protic IL diethylenetriamine methylurea ([DETAH][MEUR]) for trapping CO2 was successfully synthesized. The absorption and regeneration properties of the ILs solution were tested, and the changes in the physical properties of ILs before and after CO2 absorption were compared. The experimental results showed that the [DETAH][MEUR] solution had relatively low viscosity, excellent absorption property with 2.05 mol CO2/mol IL at 40 °C and 0.5 mol/L concentration, and its regeneration efficiencies still kept above 90.09 % after five cycles. In addition, the mechanism of the absorption reaction was explored by combining Fourier transform infrared (FT-IR) spectroscopy, carbon nuclear magnetic resonance (13C NMR) spectroscopy, and density functional theory (DFT) calculation methods. It shows that in [DETAH][MEUR] solution, the N atom losing proton (-NH) in the anion is the main absorption site, and the primary amine (-NH2) in the protonated cation [DETAH]+ of secondary amine is used as an auxiliary cooperative trapping CO2. Hopefully, this work can provide a new way for the research and development of green CO2 absorbents.

In view of the drawbacks of small specific surface area, poor thermal stability, and easy decomposition, CsPAV was modified by the organic ammonium source dimethyl diallyl ammonium chloride (DMDAAC). A series of (DMDAAC)CsPAV/SiO2 catalysts with different (DMDAAC)CsPAV loadings were prepared by an impregnation method. When DMDAAC-modified CsPAV was supported on SiO2, it exhibited a high specific surface area and more active sites. The catalytic performance of (DMDAAC)CsPAV/SiO2 was investigated by methacrolein (MAL) oxidation to methacrylic acid (MAA). The performance of the catalyst was characterized by FT-IR, XRD, TG, NH3-TPD, NMR, and XPS. There was an interaction between SiO2 and (DMDAAC)CsPAV, and the NH4+ crystalline salt was formed in the process of calcination from DMDAAC. The interaction between the formed NH4+ and SiO2 carrier prevented the decomposition of CsPAV. (DMDAAC)CsPAV/SiO2 showed high stability, and the catalytic performance was stable in the long-term evaluation test. Under the optimum conditions, the conversion of MAL was 80.8%, and the selectivity to MAA was 89.1% for 50(DMDAAC)CsPAV/SiO2.

As a predictive tool, quantum chemical calculations can be used to design protic ionic liquids (PILs) and predict the result. By adding anionic negative potential sites, two dual-functional PILs diethylenetriamine-barbituric acid [C4H14N3]2[C4H2N2O3] and diethylenetriamine-ethylenolactonium [C4H14N3]2[C3H2N2O2] were designed. The simulation results indicated that multisite absorption of anions and cations resulted in an expected absorption ratio exceeding 3:1 (mol CO2:mol ILs). Furthermore, the Gibbs free energy and enthalpy barrier were calculated. Based on this, the two PILs were synthesized in a controlled manner, and the experimental results demonstrated that 0.25 mol/L [C4H14N3]2[C4H2N2O3] and [C4H14N3]2[C3H2N2O2] exhibited a superior CO2 absorption capacity of 3.152 and 3.466 mol CO2/mol ILs, respectively. After five adsorption-desorption experiments, the regeneration rates of [C4H14N3]2[C3H2N2O2] were all higher than 90%. Finally, the reaction mechanism for CO2 capture in these PILs was revealed that the significant increase in capacity could be attributed to the combined absorption of double negative potential N atoms on anions and primary and secondary amines on cations by using 13C NMR.

In the process of recovering organic compounds from wastewater generated by propylene oxide (PO) production plant, the low concentration of propylene glycol (PG) in the wastewater makes it difficult and energy-intensive to achieve the high concentrations purify of PG using conventional distillation technology. Additionally, there is no publicly available commercial technology for this purpose. Therefore, the aim of this work is to develop an energy-efficient PG purification process based on mechanical vapor recompression (MVR) heat pump distillation combined with thermally coupled technology. Several energy-saving methods were implemented as follows. Firstly, MVR distillation technology was used to purify PG from 2.22% to 33.3% in the PG concentration tower, and the gas at the top of the tower was compressed and pressurized to serve as the heating medium for the reboiler, which significantly reduced the consumption of fresh steam. Secondly, in order to achieve heat matching, the dehydration tower was divided into two parts. The surplus steam compressed by the compressor was then served as the heat source for the reboiler of the first dehydration tower to reduce steam consumption, while achieving 98.7% water removal. Thirdly, the condenser of the de-heavy tower and the scraping film evaporator were thermally coupled to reduce the consumption of heating and cooling media. Based on the aforementioned energy-saving measures, the developed optimization process can achieve PG purification of over 90%, while significantly reducing costs. The total annual cost (TAC) is reduced by 34.89% compared to the traditional distillation process.

The complexation of palladium with bidentate phosphine ligand has significant effects on the activity of the catalyst for methoxycarbonylation of ethene. Herein, the influence of the ratio of components, kind and sequence of additives, complexation temperature and time on the catalytic performance were studied, then probable mechanism was proposed, and further kinetic studies were carried out under the optimized conditions. Compared to add Methanesulfonic acid (MSA) after complexation, the addition of an appropriate dose of MSA before complexation rather than after complexation could effectively improve the activity of the catalyst, while the addition of Methyl Propionate (MeP) would reduce the activity of the catalyst. It was worth noting that the weak absorption of [Pd-H]+ + in 1943 cm-1 was captured in the complex by in situ FT-IR.

The selective oxidation of methacrolein (MAL) to high value-added methacrylic acid (MAA) using green chemical technology is of high research value.