期刊文献+
共找到5篇文章
< 1 >
每页显示 20 50 100
稀土三元催化体系ZnO/SiO_2负载化及季铵盐催化CO_2与环氧丙烷合成高分子量聚碳酸酯(英文) 被引量:2
1
作者 程瑞华 周宇杰 +1 位作者 侯侨丽 刘柏平 《Chinese Journal of Catalysis》 SCIE EI CAS CSCD 北大核心 2018年第8期1303-1310,共8页
由环氧丙烷(PO)和CO_2交替共聚合成脂肪族聚碳酸亚丙酯,CO_2利用率高,所得产物具有一定的力学性能和生物降解性能,具有广泛应用前景.目前,用于CO_2和环氧化合物共聚的催化体系主要包含锌、钴、镉、铬、铝和稀土等金属活性中心,结构、活... 由环氧丙烷(PO)和CO_2交替共聚合成脂肪族聚碳酸亚丙酯,CO_2利用率高,所得产物具有一定的力学性能和生物降解性能,具有广泛应用前景.目前,用于CO_2和环氧化合物共聚的催化体系主要包含锌、钴、镉、铬、铝和稀土等金属活性中心,结构、活性各异的催化剂体系,其催化性能和产物性能也各具特色.其中,稀土三元催化剂(ZnEt_2-甘油-三氯乙酸钇)因合成聚碳酸酯产物的分子量高、碳酸酯单元含量高、聚醚及环碳酸酯副产物少的特点而受到关注.但是由于催化剂催化效率低,聚合时间长,产品成本高,使得工业化规模生产受到限制.本文基于稀土三元催化体系,将催化剂负载于硅胶及锌改性硅胶,优化了其制备条件,同时考察了添加季铵盐对催化CO_2/环氧丙烷共聚合成聚碳酸酯性能的影响.结果表明,在1 L聚合釜中,于3.5 MPa和70 ℃反应条件下,ZnO担载量及ZnO/SiO_2添加量对反应性能均有影响.当3 wt%ZnO/SiO_2的添加量为5 g时,稀土三元催化体系的活性为4845.2 g/mol_(Zn).所得聚合物经过多次纯化处理后,能够有效提高材料的热学性能,即有效除去产物中的ZnO对聚合物的热稳定性有重要作用.添加含有不同阴离子(F^-,Cl^-和Br^-)的季铵盐可显著影响稀土三元催化剂的活性.其中,仅四甲基氟化铵可以明显提高反应活性乃至聚合物分子量.在3 wt%ZnO/SiO_2载体和四甲基氟化铵的协同作用下,稀土三元催化体系的共聚性能明显提升,活性最高可达5223.0 g/mol_(Zn).聚合物结构分析表明,在载体和四甲基氟化铵存在下,聚合物分子量明显提高,可达到20万以上,分子量分布明显变窄,且聚合物结构如碳酸酯的单元含量、副产物含量以及聚合物产品玻璃化温度基本不变,后者均保持在40.41℃.基于此,我们提出了在ZnO改性硅胶载体及四甲基氟化铵存在下稀土三元催化体系催化CO_2/环氧丙烷共聚的反应机理:ZnO/SiO_2载体有利于稀土三元催化体系的分散。 展开更多
关键词 CO2/环氧烷烃共聚 稀土金属催化剂 ZnO改性硅胶 季铵盐 分子量
下载PDF
A sequential continuous flow synthesis and purification process of calcium dibutyryladenosine cyclophosphate
2
作者 Liming Cao Maolin Sun +6 位作者 Chaoming Liang Lei Yang Yueyue Ma ruihua cheng Yanxiong Ke Wei Yu Jinxing Ye 《Chinese Chemical Letters》 SCIE CAS CSCD 2024年第2期402-406,共5页
Calcium dibutyryladenosine cyclophosphate is a widely used cardiovascular drug.The traditional batch synthesis process suffers from long reaction times,tedious operations,and unstable yields.Herein,a sequential contin... Calcium dibutyryladenosine cyclophosphate is a widely used cardiovascular drug.The traditional batch synthesis process suffers from long reaction times,tedious operations,and unstable yields.Herein,a sequential continuous flow synthesis combined with a multistage in-line purification process of calcium dibutyryladenosine cyclophosphate was developed.The acylation reaction was completed in a continuous coil reactor at 160℃ in 20 min.And the high toxic solvent pyridine was replaced by acetonitrile.Furthermore,the multistage in-line purification process was integrated into the homemade 3D circular cyclone-type micromixer chip.Combining with the membrane phase separators,the residence time of the purification step was 30 s.The isolated yield of this sequential continuous process was 92%with 99%purity. 展开更多
关键词 Flow chemistry Calcium dibutyryladenosine cyclophosphate Continuous flow synthesis In-line purification 3D circular cyclone-type micromixer chip
原文传递
Two-step continuous flow process of sodium tanshinone ⅡA sulfonate using a 3D circular cyclone-type microreactor
3
作者 Maolin Sun Chaoming Liang +7 位作者 Liming Cao Yaguo Wang Jiasheng Yang Shiyu Hou Wei Yu Yueyue Ma ruihua cheng Jinxing Ye 《Chinese Chemical Letters》 SCIE CAS CSCD 2024年第1期290-294,共5页
A sustainable and practical process is presented for the direct synthesis of sodium tanshinone IIA sulfonate(STS).Our approach was inspired by the well-established and industrially applied batch synthetic route for ST... A sustainable and practical process is presented for the direct synthesis of sodium tanshinone IIA sulfonate(STS).Our approach was inspired by the well-established and industrially applied batch synthetic route for STS production.We constructed a telescoped two-step continuous flow platform.This involved a continuous tanshinone IIA sulfonation and in-line salt formation.For the setup,we constructed a 3D circular cyclone-type microreactor using femtosecond laser micromachining.Compared to the 68%yield for 2 h in batch,the two-step continuous flow had an STS yield of 90%,achieved for a total residence time of<3.0 min under optimal conditions.The proposed continuous flow method vastly simplified the operation and improved procedural safety,while significantly reducing the required acid content and wastewater production. 展开更多
关键词 Continuous flow Sodium tanshinone IIA sulfonate Cardiovascular MICROREACTOR Green chemistry
原文传递
Computational fluid dynamics simulation and experimental study on mixing performance of a three-dimensional circular cyclone-type microreactor
4
作者 Shiyu Hou Maolin Sun +5 位作者 Liming Cao Chaoming Liang Jiaxin Yang Xinggui Zhou Jinxing Ye ruihua cheng 《Chinese Chemical Letters》 SCIE CAS CSCD 2024年第4期382-388,共7页
Microchannels enable the fast and efficient mixing of multiphase fluids.In this study, a millimeter-scale three-dimensional(3D) circular cyclone-type microreactor was designed for the mixing.The flow characteristics a... Microchannels enable the fast and efficient mixing of multiphase fluids.In this study, a millimeter-scale three-dimensional(3D) circular cyclone-type microreactor was designed for the mixing.The flow characteristics and mixing intensity were simulated by computational fluid dynamics simulations at a flow rate range of 12–96 m L/min using a water/ethyl acetate system.In the 3D variable-diameter structure,the microreactor induced paired opposite vortices and abruptly changed the local pressure to achieve a stable turbulent effect within the theoretical range of laminar flow.Tracer injection simulations indicated that sufficient mixing units successfully promote fluid dispersion.Diazo-coupling experiments showed a segregation index of X_S= 0.00,039 within a residence time of 9 s.Extraction experiments on the nbutanol/succinic acid/water system showed that the 3D circular cyclone-type microreactor achieved 100%extraction efficiency(E) in 4.25 s, and the overall volume mass transfer coefficient(K_La) reached 0.05–1.5s^(-1) in 12–96 m L/min.The isolated yield of the phase transfer alkylation and oxidation reactions in the 3D circular cyclone-type microreactor achieved 99% within 36 s, which was superior to the coil microreactor and batch reactor. 展开更多
关键词 MICROFLUIDICS Passive microreactor CFD simulation Extraction Liquid-liquid biphase reaction
原文传递
Gas phase ethylene polymerization over SiO_(2)-supported organosilyl chromate UCC S-2 catalyst using a high-speed stirred-autoclave reactor
5
作者 Liuzhong LI Aiyou HAO +1 位作者 ruihua cheng Boping LIU 《Frontiers of Chemical Science and Engineering》 SCIE EI CSCD 2011年第1期89-95,共7页
Although an important industrial catalyst for producing high density polyethylene,the SiO_(2)-supported organosilyl chromate UCC S-2 catalyst has not been fully investigated compared with the SiO_(2)-supported oxo chr... Although an important industrial catalyst for producing high density polyethylene,the SiO_(2)-supported organosilyl chromate UCC S-2 catalyst has not been fully investigated compared with the SiO_(2)-supported oxo chromium Phillips catalyst.In this work,gas phase ethylene polymerization by S-2 catalysts(Cat-1,Cat-2,and Cat-3)was carried out in a high-speed stirredautoclave reactor.The effects of temperature,time,and pressure on kinetics,activity,and product properties were studied.All kinetics were typical built-up types with slow decay.Compared to the simple physical mixtures of Cat-1 and Cat-2,Cat-3 showed higher activity and its product had a broader molecular weight distribution,indicating new active species induced during blending of Cat-1 and Cat-2 in n-hexane.The innovation by a simple catalyst technology created a new application to meet market demands. 展开更多
关键词 UCC S-2 catalyst Al-alkyl co-catalyst gasphase ethylene polymerization high density polyethylene
原文传递
上一页 1 下一页 到第
使用帮助 返回顶部