Search | Engineering

订阅投稿

首页工程期刊工程焦点工程成就工程前沿关于我们 English

资源类型

期刊论文 6

年份

2023 1

2013 2

2012 1

2010 1

2008 1

关键词

检索范围：

排序：展示方式：

Reconstruction of Cu–ZnO catalyst by organic acid and deactivation mechanism in liquid-phase hydrogenation

《化学科学与工程前沿（英文）》 2023年第17卷第9期页码 1311-1319 doi: 10.1007/s11705-022-2281-9

摘要： A reconstructed Cu–ZnO catalyst with improved stability was fabricated by organic acid treatment method for the liquid-phase hydrogenation of dimethyl succinate to 1,4-butanediol. According to the characterization results of the fresh Cu–ZnO and reconstructed Cu–ZnO, three different forms of ZnO were suggested to be presented on the catalysts: ZnO having strong interaction with Cu species, ZnO that weakly interacted with Cu species and isolated ZnO. The first form of ZnO was believed to be beneficial to the formation of efficient active site Cu⁺, while the latter two forms of ZnO took the main responsibility for the deactivation of Cu–ZnO catalysts in the liquid-phase hydrogenation of diesters. The reconstruction of the Cu–ZnO catalyst by the organic acid treatment method resulted in a new Cu–ZnO catalyst with more Cu⁺ and less ZnO species that leads to deactivation. Furthermore, the deactivation mechanism of Cu–ZnO catalysts in liquid-phase diester hydrogenation in continuous flow system was proposed: the deposition of the polyesters on the catalysts via transesterification catalyzed by weakly interacted ZnO and isolated ZnO leads to the deactivation. These results provided meaningful instructions for designing highly efficient Cu–Zn catalysts for similar ester hydrogenation systems.

关键词： liquid phase hydrogenation Cu–ZnO deactivation mechanism 1 4-butanediol diester

HTML PDF 收藏

Deactivation and regeneration of TS-1/SiO

Hainan SHI, Yaquan WANG, Guoqiang WU, Wenping FENG, Yi Lin, Teng ZHANG, Xing JIN, Shuhai WANG, Xiaoxue WU, Pengxu YAO

《化学科学与工程前沿（英文）》 2013年第7卷第2期页码 202-209 doi: 10.1007/s11705-013-1328-3

摘要： TS-1/SiO catalyst for the epoxidation of propylene with hydrogen peroxide in a fixed-bed reactor has been investigated. The catalyst activity decreases gradually with the online reaction time, but the selectivity of propylene epoxide is kept at about 93%. The fresh, deactivated and regenerated catalysts were characterized with X-ray diffraction, Fourier transform infrared spectroscopy, ultra-violet-visible diffuse reflectance, Brunner-Emmett-Teller method and thermogravimetric analysis, and the deactivated catalyst was regenerated with H O /methanol solution. Compared with the fresh catalyst, both the framework structure and the content of titanium in the framework of the deactivated and regenerated TS-1/SiO catalysts were not changed. The major reason of the catalyst deactivation was the blockage of the channels of the catalyst by bulky organic by-products, which covered the active centers of titanium in TS-1. The deposited materials on the deactivated TS-1/SiO catalyst could be removed by treatment with hydrogen peroxide/methanol solution or pure methanol; the higher the treatment temperature and the higher the concentration of H O in methanol, the higher the extent of the regeneration. The regeneration treatment did not influence the product selectivity in the propylene epoxidation.

关键词： TS-1/SiO₂ epoxidation of propylene fixed-bed reactor deactivation regeneration

HTML PDF 收藏

Catalysis and deactivation of montmorillonite K10 in the aryl O -glycosylation of glycosyl trichloroacetoimidates

Xiaoliu LI, Xinhao YAN, Zhiwei LI, Hua CHEN, Pingzhu ZHANG,

《化学科学与工程前沿（英文）》 2010年第4卷第3期页码 342-347 doi: 10.1007/s11705-009-0279-1

摘要： The catalysis of montmorillonite K10 (MK10) for aryl -glycosylation of glycosyl trichloroacetimidates was investigated. It was found that the catalyst MK10 is deactivated gradually in the recycle glycosylation. The fresh and the deactivated catalysts were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Thermogravimetric analysis (TGA), and N adsorption-desorption. The results show that the eliminated trichloroacetamide molecule deposits on the MK10, which blocks and poisons the active sites, resulting in the deactivation of the catalyst. The regeneration of the deactivated MK10 by calcination was studied preliminarily.

关键词： photoelectron spectroscopy adsorption-desorption glycosylation deactivated diffraction

HTML PDF 收藏

Chemical deactivation of V

Xiaodong WU, Wenchao YU, Zhichun SI, Duan WENG

《环境科学与工程前沿（英文）》 2013年第7卷第3期页码 420-427 doi: 10.1007/s11783-013-0489-0

摘要： V O -WO /TiO catalyst was poisoned by impregnation with NH Cl, KOH and KCl solution, respectively. The catalysts were characterized by X-ray diffraction (XRD), inductively coupled plasma (ICP), N physisorption, Raman, UV-vis, NH adsorption, temperature-programmed reduction of hydrogen (H -TPR), temperature-programmed oxidation of ammonia (NH -TPO) and selective catalytic reduction of NO with ammonia (NH -SCR). The deactivation effects of poisoning agents follow the sequence of KCl>KOH>>NH Cl. The addition of ammonia chloride enlarges the pore size of the titania support, and promotes the formation of highly dispersed V=O vanadyl which improves the oxidation of ammonia and the high-temperature SCR activity. K ions are suggested to interact with vanadium and tungsten species chemically, resulting in a poor redox property of catalyst. More importantly, potassium can reduce the Br?nsted acidity of catalysts and decrease the stability of Br?nsted acid sites significantly. The more severe deactivation of the KCl-treated catalyst can be mainly ascribed to the higher amount of potassium resided on catalyst.

关键词： V₂O₅-WO₃/TiO₂ potassium chloride poisoning reducibility acid sites

HTML PDF 收藏

Kinetic model for hydroisomerization reaction of C-aromatics

XU Ouguan, SU Hongye, JIN Xiaoming, CHU Jian

《化学科学与工程前沿（英文）》 2008年第2卷第1期页码 10-16 doi: 10.1007/s11705-008-0015-2

摘要： Based on the reported reaction networks, a novel six-component hydroisomerization reaction network with a new lumped species including C-naphthenes and C-paraffins is proposed and a kinetic model for a commercial unit is also developed. An empirical catalyst deactivation function is incorporated into the model accounting for the loss in activity because of coke formation on the catalyst surface during the long-term operation. The Runge-Kutta method is used to solve the ordinary differential equations of the model. The reaction kinetic parameters are benchmarked with several sets of balanced plant data and estimated by the differential variable metric optimization method (BFGS). The kinetic model is validated by an industrial unit with sets of plant data under different operating conditions and simulation results show a good agreement between the model predictions and the plant observations.

关键词： ordinary differential Runge-Kutta catalyst deactivation C-paraffins optimization

HTML PDF 收藏

Effective regeneration of thermally deactivated commercial V-W-Ti catalysts

Xuesong SHANG, Jianrong LI, Xiaowei YU, Jinsheng CHEN, Chi HE

《化学科学与工程前沿（英文）》 2012年第6卷第1期页码 38-46 doi: 10.1007/s11705-011-1167-z

摘要： An effective method for the regeneration of thermally deactivated commercial monolith SCR catalysts was investigated. Two types of regenerated solutions, namely NH Cl (1 mol/L) and dilute H SO (0.5 mol/L), were employed to treat the used catalyst. The effects of temperature and the regeneration process on the structural and textural properties of the catalysts were determined by X-ray diffraction, scanning electron microscopy, N adsorption/desorption, elemental analysis and Fourier transform infrared spectroscopy. The results suggest that the anatase phase of the used catalyst is maintained after exposure to high temperatures. Some of the catalytic activity was restored after regeneration. The catalyst regenerated by aqueous NH Cl had a higher activity than that of the catalyst treated by dilute H SO . The main reason is that the NH generated from the decomposition of NH Cl at high temperatures can be adsorbed onto the catalyst which promotes the reaction. The aggregated V O were partially re-dispersed during the regeneration process, and the intrinsic oxidation of ammonia with high concentrations of O is a factor that suppresses the catalytic activity.

关键词： V₂O₅-WO₃/TiO₂ catalysts thermal deactivation regeneration NH₄Cl dilute H₂SO₄ solution