草酸二乙酯国内外研究进展

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This work reports a novel sustainable two-step method for the synthesis of ethylene glycol (EG) using syngas. In the first step, diethyl oxalate was selectively synthesized via oxidative double carbonylation of ethanol and carbon monoxide (CO) using a ligand-free, recyclable Pd/C catalyst. In the second step, the diethyl oxalate produced underwent subsequent hydrogenation using [2-(di-tert-butylphosphinomethyl)-6-(diethylaminomethyl)pyridine]ruthenium(II) chlorocarbonyl hydride to get EG and ethanol. Thus, the generated ethanol can be recycled back to the first step for double carbonylation. This method gives a sustainable route to manufacture EG using carbon monoxide and hydrogen.

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The control of steam drums, used to remove heat from Fischer–Tropsch synthesis or diethyl oxalate hydrogenation, is confronted with a challenge on controlling quality. The traditional proportional–integral–differential (PID) controllers with fixed parameters are dissatisfying upon deployment. The backward-propagation neural network (BPNN) self-tuning PID control algorithm was thus developed and implemented via a Python and KINGVIEW software combination. Application experiments showed that, in both setpoint control and step change control of the steam drum pressure, static deviation and the maximum error were less with the BPNN self-tuning PID controller, in comparison to the conventional PID controller. Moreover, it seemed that certain adaptations occurred to the nonlinear change in the reaction system, revealing that it was superior to the traditional PID controller. It is shown that the backward-propagation neural network will improve the control quality in boiling water drum systems for exothermic reactions. It can be predicted that the backward-propagation neural network is qualified for process condition control in the chemical industry.

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Two solvent free methods of a one-to-one alcohol/acid mol ratio synthesis of benzyl esters of the formic, acetic, benzoic, salicylic, nicotinic, and oxalic acids are described. The stoichiometric reactions used 1.5 mol ratio solid NbCl5 as the reagent and required from two to three hours for completion at room temperature; for the catalytic processes, NbCl5 was grafted directly, at room temperature, onto a silica gel of specific area of 507 m2g−1, produced from construction sand and sodium carbonate, forming a 5.4% Nb w/w SiO2-Nb gel with a specific area of 412 m2g−1. At 10% w/w catalyst/alcohol ratio, this SiO2-Nb catalyst gave similarly very good yields but required from 6 to 9 hours at the reflux temperature of the slurry. The catalyst could be re-used three times.

An unprecedented and highly reactive Pd/C catalytic system has been introduced for the regiodivergent hydrocarboxylation of terminal alkynes to selectively afford various acrylic and cinnamic acids employing oxalic acid as a CO source as well as a promoter for the formation of the active Pd–H complex. Herein, the formation of cinnamic acid is proposed to follow a unique anti-Markovnikov hydroiodination mechanism and the formation of acrylic acid might follow the traditional hydrocarboxylation pathway. Additionally, internal alkynes undergo hydrocarboxylation and carbonylative esterification with aliphatic alcohols to yield different α,β-unsaturated acids and esters respectively. The designed strategies were successfully leveraged for a diverse class of α,β-unsaturated acids and esters with excellent selectivity and yields under mild reaction conditions. Furthermore, the acid functionalization of complicated naturally derived alkynes, utilizing economical and bench-stable oxalic acid and a commercially accessible reusable catalyst with gram-scale applicability are the additional benefits of the established protocol.

Abstract The diethyl oxalate process features two reaction sections with two of the fresh feeds (oxygen and ethanol) and a recycle stream containing nitric oxide fed into the first reactor, which produces ethyl nitrite and water. Water is removed in a distillation column and the ethyl nitrite is fed to the second reactor along with the third fresh feed (carbon monoxide). Diethyl oxalate and nitric oxide are produced in this reactor. The product diethyl oxalate is recovered in a distillation column, and the nitric oxide is recycled back to the first reactor. The intermediate components (nitric oxide and ethyl nitrite) and inert nitrogen circulate between the two reaction sections. A recent paper proposed a plantwide control structure for this complex process that requires four on-line composition controllers to handle disturbances in throughput and the compositions of the three fresh feed streams. The purpose of this paper is to demonstrate that a less complex control structure with only one composition measurement can achieve stable regulatory control.

13-Ni/ZrO2, 13-Ni3P/ZrO2, 13-Ni/SiO2, and 13-Ni3P/SiO2 catalysts were used in the hydrogenation of diethyl oxalate (DEO) to ethyl glycolate (Egly) to investigate the modulating effect of phosphorus. XRD, TEM and FT-IR...

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Abstract In this article, the plantwide control of a novel process for diethyl oxalate production via two steps is investigated. The unique feature of this process is that there is a closed regeneration-coupling circulation. It results in that two steps should be matched properly and mass balance for overall reaction should be satisfied precisely. An effective control structure using a feedforward ratio with composition controller is determined. Later, safety analysis for this process is investigated by the integration of dynamic simulation and HAZOP (hazard and operability analysis). In comparison with heuristic HAZOP, quantitative deviations can be introduced. Quantitative variation trends and change rates of important variables can be determined. Determining increase rate in temperature and pressure is significantly important, since response time as indirect indictor can be used to assess the possibility of risk. Finally, a general procedure based on simulation for design and safety analysis of chemical process is proposed.

Abstract Diethyl oxalate (DEO) is widely used in fine chemical industry. In comparison with traditional esterification process, carbon monoxide coupling process is a novel routine for DEO production. This environmentally friendly process provides better selectivity and yield. Its unique feature is that a closed regeneration-coupling circulation is formed. Toxic byproduct-nitric oxide (NO) from coupling reaction is recycled to re-produce ethyl nitrite through regeneration reaction. This avoids significant amount of NOx emission. However, due to a few NOx emission, a contaminant handling system is applied for environmental protection. A systematical environmental analysis is also carried out to assess this process. Regeneration-coupling circulation brings interaction behaviors and some trade-offs including reactor size and recycle flowrate, regeneration and coupling reaction, loss of reactants and NO emission. Thus, a rigorous steady simulation is established to investigate these trade-offs. Then DEO process is optimized to obtain the optimal design. Finally a more economic flowsheet to produce DEO is proposed.

Micromixing in chemical reactors can be characterized through test reactions that are sensitive to mixing. A new pair of parallel competitive reactions, including acid–base neutralization and diethyl oxalate hydrolysis, is proposed in this work. It has clear principles and high sensitivity to micromixing with quantitative accuracy and operational simplicity. The measurement results obtained from stopped‐flow spectra show that the alkaline hydrolysis of diethyl oxalate follows second‐order kinetics, and the rate constant conforms to the Arrhenius equation k2 = 2.331 × 108 exp(−26.92 × 103/RT) (L/mol/s). The estimated half‐life of hydrolysis is approximately 3 × 10−4 s under the selected concentration combinations, which provides significant advantages for the micromixing assessment in the strong turbulent fluid environment. In the same stirred tank, the critical feed time of new test reaction is shorter than that of the Villermaux–Dushman reaction. Overall, this work provides practical ideas for screening other desired esters for fast hydrolysis to construct more test reactions for micromixing.

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Zeolites are highly sensitive to water, which significantly affects their acidity─a key factor in catalytic reactions. This study investigates the dynamic interactions between water and often overlooked active sites, specifically the "NMR-invisible" aluminum species (tricoordinated framework Al─FAL and cationic extra-framework Al─EFAL) in ultrastable Y (USY) zeolite under ambient conditions. Using solid-state NMR spectroscopy combined with theoretical calculations, we demonstrate that water readily undergoes dissociative adsorption on these "NMR-invisible" Al sites. This process transforms both FAL and EFAL into "NMR-visible" Al species. The formation of new Brønsted acid sites on tetra-, penta-, and hexa-coordinated FAL results in an increase of over 60% in the BAS concentration in the USY zeolite. The hydrolysis of EFAL cations leads to the formation of Brønsted/Lewis acid synergistic sites, significantly improving the catalytic activity of USY zeolite. This enhancement is evident in the improved conversion of diethyl ether to ethene in the presence of moisture.

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