Catalysts
·
2020
·Vol. 10
·期 6
·715
·
IF 3.52
Yong He,Ye Yuan,Zhihua Wang,Longlong Liu,Jiaxin Tan,Jiahao Chen,Kefa Cen
The gasification experiments of coal chars with CO2were carried out isothermally, with K, Ca, Ni, and Zn chloride catalysts, adopting a thermal gravimetric analyzer (TGA) from 800 to 1100 °C. The kinetic characteristic of the samples were described using the volumetric model (VM), the grain model (GM), and the random pore model (PRM). The morphology patterns of the samples were tested applying X-ray diffraction (XRD) and the catalytic mechanisms concerning the phase changes were proposed. The results confirm that the gasification rate and char reactivities are enhanced by K, Ca and Ni chlorides, while ZnCl2inhibited the process. The catalysis ability shows the following cation order: Ca > K > Ni > Zn. Among the models described above, PRM was proven to give the best fitting value and hence adopted to kinetics parameters calculation. The activation energies in promoting conditions were lower than that of the uncatalyzed cases. In view of the catalytic mechanism, the K metals tend to form intermediate complexes and repeatedly connect with coal char, while the Ca species may follow the oxidation-reduction mechanism and the Ni metals catalyze the gasification process.Keywords:char gasification;catalytic kinetics;catalytic mechanisms;metal chlorides
研究领域:
化学工程
·
能源科学
✓ 已验证
产品关联
DOI
高影响因子
POLYMER
·
2025
·
IF 4.5
Junjie Liu,Jianmin Wu,Qiwen Sun,Jiancheng Wang,Yan Sun
The high viscosity index poly-alpha-olefin was prepared by 1-decene polymerization under [EBIZrCl 2 /Al( i Bu) 3 /[Ph 3 C] + [B(C 6 F 5 ) 4 ] - system (EBI = rac-C 2 H 4 (1-Ind) 2 ), and its mechanism was investigated by in situ UV–Vis, 1 H NMR and ESI-MS. The results show that the kinematic viscosity at 100 °C (KV 100 ), viscosity index (VI) and yield of product reach to 336.3 cSt, 268 and 90.76 % under optimum reaction condition, wherein Zr/1-decene content, Al/Zr content, B/Zr content, reaction temperature and time are 10 −4 , 200, 2, 90 °C and 120 min, respectively. Meanwhile, temperature plays a crucial role in controlling the KV 100 and VI of product, with impact index of 55.43 % and 44.32 %, respectively. In situ UV–Vis, 1 H NMR, and ESI-MS analyses confirm the simultaneous generation of active (EBIZr-σ-polydecenyl cations) and inactive species (EBIZr-η 3 -(1-propyl-C 7 H 8 ) + ). The active and inactive species are generated through posing complexation to the terminal allyl of 1-decene and H 2 loss of EBIZr(u- i Bu) + , respectively. The second inactivate species (EBIZr-η 3 -(x-propyl-(3-x)-polydecenyl-C 3 H 3 ) + (x = 1 or 2)) can be activated by seizing isobutyl group in Al( i Bu) 3 . Subsequently, the polymer with an Al-capped saturated chain end is formed through chain migration. The polymerization process follows the reaction pathway: [1-decene]+[catalyst]→[active species]+[inactive species]. This is supported by the fact that all fitting curve of conversion versus time, 1-decene consumption and polymer generation conform to the Boltzmann (R 2 = 0.999). Based on those findings, a possible mechanism in ansa-zirconocene catalyzed polymerization of 1-decene is proposed.
研究领域:
高分子化学
·
催化化学
✓ 已验证
DOI
高影响因子
APPLIED CATALYSIS A-GENERAL
·
2020
·
IF 5.006
Haodong Duan,Xiaolei Xu,Kangwei Leng,Ge Guo,Qing Yu,Xinjin Li,Yuxi Han,Jun Gao,Zhongwei Wang
The characteristics of the reaction for the preparation of dichlorophenylphosphine (DCPP) via benzene and PCl 3 in the presence of AlCl 3 were studied. Some unique characteristics were observed when a catalytic amount of AlCl 3 was used. Namely, more than one mole of DCPP was obtained per mole AlCl 3 , the reaction solution was layered, and DCPP could be directly separated. Our mechanistic study showed that benzene reacted with PCl 3 to form DCPP-AlCl 3 , and DCPP-AlCl 3 dissociated into DCPP and AlCl 3 , continuing to catalyze this reaction. This resulted in the high catalytic efficiency of AlCl 3 . The layering of the reaction solution was caused by the immiscibility of DCPP-AlCl 3 with the raw materials, greatly facilitating the dissociation process of DCPP-AlCl 3 . The formation of diphenylphosphorus chloride (DPC) was due to a continuous Friedel-Crafts reaction between DCPP and benzene. DPC cooperated with AlCl 3 to form the stable coordination compound DPC-AlCl 3 that did not dissociate and was responsible for the deactivation of AlCl 3 .
研究领域:
有机化学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
INTERNATIONAL JOURNAL OF HYDROGEN ENERGY
·
2019
·
IF 4.084
Bogu Liu,Bao Zhang,Ying Wu,Wei Lv,Shixue Zhou
Transition metals, including Ni, show good catalytic activity in the hydrogen storage reaction of Mg. In the present paper, first-principles calculation is performed to predict and analyze the hydriding reaction of Ni-incorporated Mg and experimental study is used to verify the accuracy of the forecast. Theoretical studies show that the hydriding reaction of Ni-incorporated Mg is a diffusion-controlled process. With Ni incorporation, the energy barrier of H 2 dissociation is significantly decreased and the diffusion becomes the limiting step. Experimental studies confirm the results of theoretical studies. Besides, the material with Ni incorporation shows excellent activation performance and rapid absorption rates, leading to a high hydrogen content of 4.1 wt% in 60 s under 240 °C 3.0 MPa H 2 and a low activation energy of 56.1 kJ mol −1 versus 0.4 wt% and 73.5 kJ mol −1 for the material without Ni incorporation. Atomic Ni only plays a role of catalyst.
研究领域:
材料科学
·
物理化学
✓ 已验证
DOI
高影响因子
Catalysis Science & Technology
·
2017
·Vol. 7
·期 9
·1838-1847
·
IF 5.773
Yi Zhang,Zhenyun Lan,Ni Jian,Zhuanghe Ren,Jianjiang Hu,Mingxia Gao,Hongge Pan,Yunhao Lu,Yongfeng Liu
In this work, we demonstrate a first attempt at understanding the catalytic mechanism of nanosized Co in reducing the dehydrogenation temperature of the Li–B–N–H hydrogen storage system by experimental observation and theoretical calculation. A nanosized Co@C composite (Co particles <10 nm) is successfully synthesized by casting a furfuryl alcohol-filled, Co-based metal–organic framework, MOF-74(Co), at 700 °C. Adding small quantities of the prepared nanosized Co@C composite significantly reduces the dehydrogenation temperature of the LiBH4–2LiNH2 system. The 5 wt% Co@C-containing sample releases approximately 10.0 wt% hydrogen at 130–230 °C with a peak temperature of 210 °C, which is reduced by 125 °C from that of the pristine sample. During hydrogen desorption, nanosized Co remains in the metallic state and only works as a catalyst to reduce the kinetic barriers of hydrogen release from the LiBH4–2LiNH2 system. Ab initio calculations reveal that the presence of a Co catalyst induces a redistribution of charge, which not only weakens the chemical H–B bonding but also enhances the electrostatic interactions between Hδ+ in the NH2 groups and Hδ− in the BH4 groups, consequently reducing the energy barriers for the formation of H2 molecules. This explains the low-temperature dehydrogenation behaviour of the Co-catalysed Li–B–N–H systems.
研究领域:
材料科学
·
能源化学
·
催化化学
·
氢能源存储
·
纳米技术
✓ 已验证
DOI
高影响因子
MATERIALS CHEMISTRY AND PHYSICS
·
2014
·
IF 2.129
Xiaodan Li,Xiaoyong Luo,Ming Liu,Qichao Ran,Yi Gu
Two model compounds, 3-Phenyl-3,4-dihydro-2H-1,3-benzoxazine (PA) and 6,8-dimethyl-3-(2,4,6-trimethyl-phenyl)-3,4-dihydro-2H-1,3-benzoxazine (s-PA), were successfully synthesized and purificated. Compared with PA, s-PA also catalyzed the polymerization of BADCy even though there was no phenolic hydroxyl in its final ring-opened structures. It was confirmed that the real mechanism of benzoxazine catalyzing the polymerization of cyanate ester is the nucleophilic addition reaction of the oxygen anion on ring-opened benzoxazine to the positively charged carbon atom on cyano group. The catalytic effect also contains the contribution from the phenolic hydroxyl, but it is a secondary factor.
研究领域:
材料科学
·
化学工程
✓ 已验证
产品关联
DOI
高影响因子
CHINESE JOURNAL OF POLYMER SCIENCE
·
2019
·Vol. 37
·期 12
·1205-1214
·
IF 2.804
Jiang Zhuo-Lun,Zhao Jun-Peng,Zhang Guang-Zhao
Highly potent ionic organocatalyst is developed for room-temperature controlled ring-opening polymerization (ROP) of lactones, including δ -valerolactone, ε -caprolactone, and δ -hexalactone. The catalysts are prepared by simply mixing tetra- n -butyl ammonium hydroxide and a (thio)urea at elevated temperature under vacuum, and used in cooperation with an alcoholic initiator. The performance of the catalyst is readily adjusted and optimized through variation of the (thio)urea precursor, catalyst composition, and reaction condition. Urea-derived catalysts are generally superior to thiourea-derived ones. Provided with proper N -substituents, the catalyst affords both high polymerization efficiency and high selectivity for monomer enchainment over macromolecular transesterification, even at high monomer conversion and/or substantially extended reaction time. In addition to acidity, structural symmetry of the urea also proves decisive for the catalytic activity, which enables a catalyst-assisted proton transfer process for the ring-opening of lactone and thus provides a novel mechanistic insight for ROP catalyzed by hydrogen-bonding type bifunctional ionic organocatalysts.
研究领域:
高分子化学
·
有机化学
✓ 已验证
DOI
高影响因子
Inorganic Chemistry Frontiers
·
2020
·Vol. 7
·期 17
·3204-3216
·
IF 5.958
Chaoyue Zhao,Xianming Zhang,Ziting He,Qingxin Guan,Wei Li
For acetylene hydrochlorination, as a substitute for toxic mercury catalysts, Cu-based catalysts are probably the most promising and highly active non-noble metal catalysts. Here, density functional theory (DFT) was used to reveal the mechanism for how the NMP ligand significantly promotes the activity and stability of the Cu-catalyzed acetylene hydrochlorination reaction. According to the experimental and DFT results, the high activity of the NMP coordinated Cu-based catalyst is attributed to the catalyst–ligand and substrate–ligand interactions, which stabilize the substrate-Cu(II)-ligand complex in the catalytic cycle. Moreover, the most important two stages were investigated in detail: the reduction of (i) Cuα+ to Cu0 and (ii) Cu2+ to Cu+ during the reaction process. The results demonstrate that the NMP ligand prevents high valence Cu2+ from being reduced due to the geometric distortion influence and the hydrogen bond interaction between the catalysts and ligands. Also, NMP could inhibit the carbon deposition by avoiding the formation of Cu(0) and its strong adsorption of acetylene on the surface.
研究领域:
化学
·
催化科学
·
理论计算
✓ 已验证
产品关联
DOI
高影响因子
NEW JOURNAL OF CHEMISTRY
·
2023
·Vol. 47
·期 16
·7583-7587
·
IF 3.3
Baole Li,Tiansheng He,Chen Zuo,Zhi Cao,Taihong Yan,Weifang Zheng
Catalytic decomposition of hydrazine nitrate is a very important research topic in the environmental protection field. Herein, we used an Ru/C catalyst for the decomposition of hydrazine nitrate in HNO3, and the reaction kinetics and mechanism were studied in detail. The kinetics study of the decomposition of hydrazine nitrate (0.01 M) was conducted in the temperature range 313–343 K in 0.1 M HNO3 in the presence of Ru/C. The apparent activation energy for this reaction was 46.6 kJ mol−1 according to a fitting of the experimental data, while the reaction order was 1.5. It was also found that the reaction pathway of the catalytic decomposition of hydrazine nitrate on the Ru/C catalyst involved two processes: heterogeneous catalytic disproportionation of hydrazine nitrate at the catalyst surface and oxidation of hydrazine nitrate with catalytically generated HNO2.
研究领域:
环境科学
·
催化化学
✓ 已验证
产品关联
DOI
高影响因子
Frontiers of Chemical Science and Engineering
·
2023
·Vol. 17
·期 12
·1925-1936
·
IF 4.5
Ma Jianzhong,Wen Lu,Fan Qianqian,Wei Siying,Hu Xueyun,Yang Fan
In recent years, limited photocatalysis efficiency and wide band gap have hindered the application of TiO 2 in the field of photocatalysis. A leading star in photocatalysis has been revealed as lead-free Cs 2 AgBiBr 6 double halide perovskite nanocrystals, owing to its strong visible light absorption and tunable band gap. In this work, this photocatalytic process was facilitated by a unique TiO 2 /Cs 2 AgBiBr 6 composite, which was identified as an S-cheme heterojunction. TiO 2 /Cs 2 AgBiBr 6 composite was investigated for its structure and photocatalytic behavior. The results showed that when the perovskite dosage is 40%, the photocatalytic rate of TiO 2 could be boosted to 0.1369 min −1 . This paper discusses and proposes the band gap matching, carrier separation, and photocatalytic mechanism of TiO 2 /Cs 2 AgBiBr 6 composites, which will facilitate the generation of new ideas for improving TiO 2 ’s photocatalytic performance.
研究领域:
材料科学
·
环境科学
·
化学
✓ 已验证
DOI
高影响因子
ACS Omega
·
2019
·
IF 2.584
Zhongyi Jiao,Zhendong Liu,Zhen Ma
Novel AgI/Ag2Mo2O7 heterojunctions were prepared by reacting Ag2Mo2O7 microrods with an aqueous KI solution at room temperature. The composite materials, compared with neat AgI and Ag2Mo2O7, showed much higher activities in the photocatalytic degradation of aqueous rhodamine B, methyl orange, tetracycline hydrochloride, and levofloxacin solutions under visible-light irradiation. The structures, morphologies, and other physicochemical properties of AgI, Ag2Mo2O7, and AgI/Ag2Mo2O7 composites were studied via various characterization techniques. The active species involved in the photocatalytic process were examined via radical-capturing experiments and electron spin resonance. Superoxide anion radicals (•O2–) and photogenerated holes (h+) were found to be the main active species. Photocatalytic mechanisms were proposed and reasons for the enhanced photocatalytic activity were explained.
研究领域:
材料科学
·
环境科学
·
化学
✓ 已验证
产品关联
DOI
PubMed
高影响因子
APPLIED SURFACE SCIENCE
·
2020
·
IF 6.182
Yinghui Hu,Bowen Tao,Fei Shang,Meixue Zhou,Dongyu Hao,Ruiqing Fan,Debin Xia,Yulin Yang,Aimin Pang,Kaifeng Lin
Perovskite-based catalysts show a versatile catalytic ability for redox reactions, but are seldom applied for ammonium perchlorate (AP) decomposition. Their catalytic mechanism on AP decomposition still remains unknown. In this study, four different perovskites, namely LaCoO 3 , La 2 CuO 4 , LaMnO 3 and LaNiO 3 , were prepared by co-precipitation method and then applied to catalyze the AP decomposition. LaCoO 3 exhibited the best catalytic performance among all the perovskites used, in which the decomposition temperature of AP was lowered to 301.1 °C (114.9 °C lower than pure AP) and the heat release was increased from 768 to 1428 J g −1 . A series of characterization on these four perovskites, such as XRD, SEM, NH 3 -TPD, O 2 -TPD and XPS, revealed that stronger adsorption abilities of catalysts for NH 3 and O 2 on the surface led to better catalytic performance, thus explaining their differences in the catalytic performance. Online TG/FT-IR further revealed that perovskite catalysts could significantly inhibit the conversion of N 2 O to NO, which was benefit to the enhancement of heat release. Finally, the perovskite catalysts were mixed with HTPB-based propellant to test their real application, and the results showed that perovskite containing HTPB-based propellant exhibited an increased burning rate and combustion heat, thus demonstrating their potential application in solid propellant.
研究领域:
材料化学
·
物理化学
·
催化化学
·
推进剂技术
·
能源材料
✓ 已验证
DOI
高影响因子
危险品化学品经营许可证（带存储）