PROCESS SAFETY AND ENVIRONMENTAL PROTECTION
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2022
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IF 7.926
Qingwei Song,Lei Ni,Juncheng Jiang,Zhiquan Chen,Gang Fu,Hang Yao,Zhen Cheng
In this study, diphenyl sulfoxide was prepared by oxidizing diphenyl sulfide with hydrogen peroxide using phosphotungstic acid as catalyst in semi-batch mode. In order to optimize the synthesis process, a four-factor three-level Box-Behnken design was adopted. The result showed that under the optimal condition, namely catalyst concentration 0.19 mmol/mol, oxygen-sulfur ratio 1.08, reaction temperature 30 ºC, and dosing time 15 min, the yield of diphenyl sulfoxide could reach up to 79.05%. In addition, the thermal behavior of synthesis process was systematically investigated using a reaction calorimeter (EasyMax 102) equipped with a situ FTIR monitoring. The receivable mechanism is that H 2 O 2 is activated by the catalyst and subsequently reacts with diphenyl sulfide to produce oxidized product. H 2 O 2 was relatively stable when PTA was used as catalyst. Thermal risk index was used to assess the thermal hazard of H 2 O 2 & PTA. Furthermore, risk matrix method as well as Stoessel criticality diagram was used to assess the thermal risk of the process and an unacceptable risk was obtained. One of the main hidden dangers was the potential chemical splatter caused by decomposition of H 2 O 2 . It should be equipped with a pre-set quench or sufficient emergency discharge to avoid further loss. The results of this work proposed a solid foundation for the safe operation of this process and can be further used for scale-up.
研究领域:
化学工程
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安全科学
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DOI
高影响因子
Catalysts
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2023
·Vol. 13
·期 2
·371
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IF 3.9
Xue-Jiao Liu,Bao-Di Ma,Xiao-Mei Wu,Yi Xu
A recombinantE. coli, expressing nitrilase fromAcidovorax facilis72W with dual-site expression plasmid pRSFduet (E. colipRSF-AfNit2), was constructed. It showed higher soluble expression of nitrilase than that in the pET21a plasmid. The recombinant nitrilase can efficiently catalyze the hydrolysis of 3-cyanopyridine to nicotinic acid. The whole cells ofE. colipRSF-AfNit2 were immobilized by using sodium alginate/glutaraldehyde/polyethylene imine as the best immobilized reagents. The immobilized cells showed 95% activity recovery and excellent mechanical strength, with improved thermal stability and pH stability. They also retained 82% of initial activity after nearly two months of storage at 4 °C. A semi-continuous packed-bed bioreactor (sPBR) filled with the immobilized cells was studied for efficient production of nicotinic acid. After optimization, the highest space–time yield of 1576 g/(L·d) was obtained on 0.8 M substrate concentration at 2 mL/min of flow rate. The sPBR was repeatedly operated for 41 batches, keeping 100% conversion in the presence of 30 mM CaCl2. Finally, 95 g of nicotinic acid were obtained at 90% yield after separation and purification. The developed technology has potential application value.Keywords:nitrilase;cell immobilization;nicotinic acid;reaction optimization;semi-continuous packed-bed bioreactor
研究领域:
生物技术
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生物化工
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微生物学
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产品关联
DOI
高影响因子
CHEMICAL ENGINEERING SCIENCE
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2023
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IF 4.7
Junyang Liu,Zengxi Li,Yuhang Bian,Guoliang Zhang,Jie Li,Gang Wang,Chunshan Li
Synthesis of methyl methacrylate (MMA) by aldol condensation of methyl propionate (MP) with formaldehyde (FA) has received researchers’ attention in recent years. Herein, a kind of acid-base bi-functional Cs/Ti-SiO 2 was developed for the conversion of MP and FA to MMA. A series of Cs/Ti-SiO 2 samples with different acid-base properties were prepared by changing the loading amount of Cs and Ti elements and characterized using XRD, BET, FT-IR, DR UV–vis, SEM, TEM, XPS, CO 2 /NH 3 -TPD, O 2 -TPO, py-IR, and TGA. The introduction of Ti species could significantly regulate the acidity and affect the surface structure of catalyst, facilitating the activation of reactants and aldol reaction effectively. The relationship between the acid-base properties and catalytic activity was correlated, which revealed the crucial role of weak and medium acid sites in this transformative process. The production of MMA was optimized by using response surface methodology (RSM) based on the Box-Behnken design (BBD) approach. As a result, 62.8 % yield of MMA with selectivity of 75.6 % could be achieved at optimal reaction conditions. The catalyst would suffer deactivation from carbon deposition, which could be easily regenerated by simple thermal treatment without any decrease in initial activity during 600 h time-on-stream. Kinetic studies unraveled the activation energy of aldol condensation was 112.2 kJ/mol.
研究领域:
催化化学
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材料科学
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有机合成
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产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
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2022
·Vol. 46
·期 27
·12934-12940
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IF 3.925
Hansen Yang,Zhimiao Wang,Hualiang An,Qiusheng Yang,Wei Xue,Fang Li,Yanji Wang
Theobromine is an important pharmaceutical intermediate and food additive. We have developed a green method for theobromine synthesis, namely catalyst-free methylation of 3-methylxanthine with dimethyl carbonate (DMC). The effects of various solvents on the reaction were investigated; H2O was found to be the most appropriate solvent. The bond energies of C–O in DMC and N–H in 3-methylxanthine were calculated at the M06-2x/6-311G(d,p) level, and the role of the solvent was examined theoretically. The use of H2O as the solvent and the effects of DMC hydrolysis on the reaction were investigated. The results show that DMC hydrolysis was, to some extent, beneficial to theobromine synthesis. The reaction conditions were optimized. When the molar ratio of DMC to 3-methylxanthine was 11 : 1 and the 3-methylxanthine dosage was 0.1 g per mL-H2O, reaction at 160 °C for 9 h gave a 3-methylxanthine conversion of 89.9% with 98.2% theobromine selectivity.
研究领域:
药物化学
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绿色化学
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有机合成
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产品关联
DOI
高影响因子
GREEN CHEMISTRY
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2025
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IF 9.2
Ning Li,Zhixun Li,Yangli Cui,Lan Liang,Wenchao Peng,Zhanjun Cheng,Beibei Yan,Guanyi Chen
Biodegradable plastics (BPs) have emerged as a promising, sustainable, and alternative to traditional ones. It is essential to concentrate on BPs waste recycling and upgrading. Chemical upcycling approach not only retains the intrinsic carbon value of the polymers, but also offers broad adaptability and high conversion efficiency across diverse types of BPs through precise reaction condition optimization. This review systematically summarizes the factors influencing BPs conversion and the mechanisms of various chemical conversion techniques. The advantages and limitations of various conversion technologies, such as pyrolysis, hydrolysis, alcoholysis, electrocatalysis, and photocatalysis, were evaluated across five dimensions, including product value, selectivity, conversion rate, cost, and carbon emissions. Pyrolysis can produce high-value products, but it is limited by high energy consumption and low selectivity. Hydrolysis and alcoholysis, both mature and reliable technologies, offer high selectivity and conversion efficiency but require optimized conditions for effective implementation. Electrocatalysis and photocatalysis appear as promising technologies for waste-to-resource conversion, aligning well with green development goals. However, both require further advancements in catalyst design and reaction optimization. Future research should focus on integrating multiple technologies, enhancing catalyst efficiency, improving pretreatment processes, and refining reaction modeling to create more sustainable and cost-effective BPs upcycling strategies. This work aims to provide theoretical support and guidance for waste plastic upcycling.
研究领域:
环境科学
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高分子化学
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化学工程
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绿色技术
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废弃物管理
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DOI
高影响因子
危险品化学品经营许可证（带存储）