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1.
In order to separate ZSM-5 zeolite powders from solution easily, a series of magnetic ZSM-5 zeolites were prepared by hydrothermal synthesis with the addition of magnetic Fe3O4 panicles during the crystalline process. The products were characterized by X-ray diffraction （XRD）, scanning electron microscopy （SEM）, infrared （IR） spectrum, energy dispersive X-ray （EDX）, specific surface area, magnetic susceptibility and adsorption capability. It was found that the magnetic ZSM-5 zeolites had good magnetism and the magnetic susceptibility increased with the increasing amount of Fe3O4 panicles. Compared with the pure ZSM-5 zeolite, the adsorption capability of magnetic ZSM-5 zeolites was acceptable. When the magnetic zeolites were used to adsorb Pb^2＋ from solution, the magnetic zeolite powder could be conveniently separated with magnetic separation technology. 相似文献
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WANG Bao-lin 《重庆大学学报(英文版)》2015,14(2):39-53
The acidities of different SiO2/Al2O3 ratio ZSM-5 zeolites, CBV3024E, CBV5524G and CBV8014 were investigated with temperature-programmed desorption of ammonia and diffuse reflectance infrared Fourier transform spectroscopy, and their catalytic performances were evaluated to screen the optimal CBV8014 catalyst for ethylene oligomerization. The mesoporosity development in CBV8014 zeolite was conducted by desilication in alkaline medium. The porous characteristics, structural properties and acidic properties of parent and alkali-treated CBV8014 zeolites were studied, and their catalytic performances were evaluated, indicating that CBV8014 treated by 0.2 mol/L NaOH solution has an appropriate mesoporosity development, well preservation of catalyst acidity and crystallinity, good catalytic activity and stability, and high liquid fuel yield for ethylene oligomerization. The effect of reaction pressure on ethylene oligomerization over 0.2HZ catalyst was also investigated, and JP-8 likely hydrocarbon jet fuel was obtained by using 0.2HZ catalyst at 0.344 75 MPa with a high catalyst stability and high liquid yield. 相似文献
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Titanium silicate-1(TS-1) was treated with a mixed alkaline of tetrapropyl ammonium hydroxide(TPAOH) and NaOH. It was characterized by XRD, nitrogen physical adsorption, SEM, FT-IR, UV-Vis and ICPOES, and studied in propylene epoxidation. The mixed alkaline treatment with TPAOH/NaOH solution did not destroy the MFI structure of TS-1. With increasing NaOH concentrations, the relative crystallinity and the framework titanium decreased to some extent while the mesopore volume, mesopore diameter, and extra-framework titanium increased appreciably. When NaOH concentration was 0.0333 mol L~(-1), the best catalytic performance was obtained. 相似文献
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Wang Yaquan Fan Chunyang Li Hongyao Wang Xiao Meng Fanjun Sun Chao Sun Liying 《天津大学学报(英文版)》2019,25(1):9-22
ZSM-5 aggregates consisting of superfine and hierarchical nanocrystals(combined with micropores and intra-crystalline mesopores) with an average size of 30 nm were prepared through one-pot synthesis with the assistance of anionic polyacrylamide(APAM). The resultant zeolites(AHN-ZSM-5) were characterized by XRD, ICP-OES, SEM, TEM, BET, NH_3-TPD, Py-IR, and TG analyses and evaluated in the methanol to gasoline(MTG) reaction. Characterization results show that the hierarchical ZSM-5 aggregates possessed two kinds of mesopores, namely inter-and intra-crystalline mesopores. The amount of APAM considerably influenced the mesoporosity and textural properties of AHN-ZSM-5 zeolites. With the addition of APAM in the synthesis, the AHN-ZSM-5 zeolites exhibited large mesopore volume, large external surface area, and appropriate acidity. When applied in the MTG reaction, AHN-ZSM-5 demonstrated a catalytic lifetime that was 1.6 times longer than that of conventional ZSM-5 synthesized in the absence of APAM. 相似文献
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MgO改性HZSM-5催化剂上甲醇制烯烃反应性能研究 总被引：6，自引：0，他引：6
采用浸渍法制备了不同含量MgO改性的HZSM-5催化剂,用XRD和吡啶吸附IR光谱两种实验手段对改性后的沸石进行表征,并考察了改性后的沸石样品对甲醇制烯烃反应的催化活性。结果表明,采用硝酸镁对HZSM-5的改性能够在催化剂表面形成MgO晶粒,起到窄化沸石孔道的作用,增加了HZSM-5的择形催化性能,并降低沸石表面的酸性,从而显著提高了HZSM-5沸石对低碳烯烃的选择性。 相似文献
7.
文章从改变催化剂和生物合成法两个方面综述了近年来己二酸绿色化学合成的研究进展,着重介绍了以环己烯、环己酮、环己醇或其混合物为原料,以过氧化氢或空气为氧源,用不同催化利及其配体催化氧化合成己二酸。 相似文献
8.
《浙江大学学报(A卷英文版)》2021,(2)
A co-reaction of methane with methanol over zeolite catalysts has emerged as a new approach to the long-standing challenge of methane transformation. However, the effect of catalyst acid properties on the co-reaction has been rarely studied. In this study, a series of HZSM-5 zeolites with comparable diffusion abilities and various acidities were synthesized directly through steaming with 100% water vapor at 693 K. The co-reaction of methane and methanol was subsequently evaluated. Br?nsted acidity at 0.262 mmol/g was detected to reach the maximum methane conversion of 5.42% at 673 K, which was also the odd point in the relationship between acid concentration and C4 hydrogen transfer index. Moreover, the influence of methanol feed was investigated over parent and steamed ZSM-5 catalyst, with results showing that excessive acid sites or methanol molecules reduce methane conversion. It is proposed that acid sites adsorbed with methanol molecules construct the methane activation sites. Hence, a proper design of zeolite acidity should be achieved to obtain higher methane conversion in the co-reaction process. 相似文献
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Diesel emission fluid (DEF) soaking and urea deposits on selective catalytic reduction (SCR) catalysts are critical issues for real diesel engine NH3-SCR systems. To investigate the impact of DEF soaking and urea deposits on SCR catalyst performance, fresh Cu-zeolite catalyst samples were drilled from a full-size SCR catalyst. Those samples were impregnated with DEF solutions and subsequently hydrothermally treated to simulate DEF soaking and urea deposits on real SCR catalysts during diesel engine operations. Their SCR performance was then evaluated in a flow reactor with a four-step test protocol. Test results show that the DEF soaking leached some Cu from the SCR catalysts and slightly reduced their Cu loadings. The loss of Cu and associated metal sites on the catalysts weakened their catalytic oxidation abilities and caused lower NO/NH3 oxidation and lower high-temperature N2O selectivity. Lower Cu loading also made the catalysts less active to the decomposition of surface ammonium nitrates and decreased low-temperature N2O selectivity. Cu loss during DEF impregnation released more acid sites on the surface of the catalysts and increased their acidities, and more NH3 was able to be adsorbed and involved in SCR reactions at medium and high temperatures. Due to lower NH3 oxidation and higher NH3 storage, the DEF-impregnated SCR catalyst samples showed higher NO x conversion above 400 °C compared with the non-soaked one. The negative impact of urea deposits during DEF impregnation was not clearly observed, because the high-temperature hydrothermal treatment helped to remove the urea deposits. 相似文献
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以丙烯酸和环己醇为原料合成丙烯酸环己酯,考察了不同催化剂、阻聚剂用量、催化剂用量、醇酸比及反应时间对丙烯酸转化率和选择性的影响,得到的最佳工艺条件为：催化剂为甲基苯磺酸,用量为1%,醇酸比为1.5,阻聚剂为3‰,带水剂用量为5%,丙烯酸转化率大于90%,选择性大于80%. 相似文献
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本文研究了正己烷在Cu改性ZSM-5上的芳构化反应。发现引入适量的Cu可提高芳构化反应的选择性和芳烃收率，考察了催化性能与酸性的关系。Cu的引入使ZSM－5沸石的L酸量增加，B酸量减少，芳构化性能增强。提出了B酸和L酸中心的协同效应对芳构化反应的促进作用。 相似文献
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本文对Ｎｉ，Ｃｕ，Ｚｎ三种金属改性的ＺＳＭ－５上正己烷的芳构化反应进行了探讨和比较，发现这些金属的引入在促进正己烷的芳构化性能方面既有共同点，也有某些差异，同时还研究了催化性能和酸性的关系，并就Ｂ酸和Ｌ酸中心的协同效应对芳构化的促进作用提出了看法。 相似文献
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M-ZSM-5分子筛的结构及催化性能研究进展 总被引：3，自引：0，他引：3
探究了ZSM-5分子筛的晶体结构、孔结构及酸性质：对通过离子变换对其表面进行优化以提高催化活性方面的研究工作进行了阐述；对Cu-ZSM-5分子筛上NO直接催化分解反应提出了：4CuO=2Cu20＋02，2Cu2O＋4NO=4CuO＋2N2＋O2的反应机理。 相似文献
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以廉价的工业废弃物粉煤灰作为初始原料,四丙基氢氧化铵（TPAOH）为模板剂,分别采用两种合成方案制备出微孔分子筛ZSM-5样品。该法相较传统水热法,原料价廉易得,制备工艺简单。通过XRD、SEM、TR等手段对样品进行表征,发现两种方案均合成出了较高质量的ZSM-5,但形貌分别为薄片型和长六方体型。最后考察了其对水中Cr（Ⅵ）离子的吸附性能,结果表明合成的ZSM-5型样品对Cr（Ⅵ）离子有较好的吸附性能。 相似文献
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Sai-sai Cheng Yuan Li Shi-jie Geng Luan-sha Hu Xiong-feng Fu Xin-yan Han 《Journal of Zhejiang University. Science. B》2017,18(12):1083-1092
This study was conducted to investigate the effects of fresh fermented soybean meal (FSM) on the growth performance of nursery piglets, nitrogen excretion in feces, and the concentrations of ammonia (NH3) and particulate matter (PM) in the piggery. A total of 472 nursery piglets (Landrace×Yorkshire, (16.3±0.36) kg body weight) were randomly allocated into two treatments with 236 pigs in each treatment. The pigs were fed the basal diet without fresh FSM (control) or diet containing 10% (100 g/kg) fresh FSM (FSM group), and the crude protein content of the two groups was consistent. The feeding trial lasted for 28 d. The results showed that the pigs fed fresh FSM had increased (P<0.05) average daily gain (ADG) compared with the control. There was no significant difference (P>0.05) in feed to gain ratio (F:G) between the two groups. During the whole experiment, the concentration of NH3 in the piggery decreased (P<0.05) by 19.0%, and the concentrations of PM (PM10 and PM2.5) in the piggery decreased (P<0.05) by 19.9% and 11.6%, respectively, in the FSM group, compared with the control. The ammonia nitrogen and nitrite content in feces increased (P<0.05) by 32.9% and 28.4%, respectively, in the FSM group. The fecal pH declined (P<0.05) significantly in the FSM group compared with the control. At the end of experiment, total protein (TP) concentration was increased (P<0.05) significantly and blood urea nitrogen (BUN) concentration was decreased (P<0.05) for pigs fed the diet with fresh FSM. The results indicated that dietary fresh FSM not only improved the growth performance of nursery piglets, but also reduced the NH3 concentration in the piggery due to nitrogen conversion, and decreased the concentrations of PM10 and PM2.5 in the piggery. 相似文献
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Saline soil stabilization is being increasingly applied in foundation treatment engineering. Chloride saline soil obtained from sites and laboratory-made chloride soil (ZS) with various NaCl concentrations prepared artificially were stabilized using alkali-activated slag (AS). A series of unconfined compressive strength (UCS) tests, X-ray diffraction (XRD), energy-dispersive X-ray analysis (EDXA), thermal gravity-differential thermal gravity (TG-DTG), and ion concentration tests were conducted to investigate the strength variation and mechanism of the AS-stabilized chloride saline soils. The results showed that NaCl has a significant influence on the strength of AS-stabilized chloride saline soil and the strength of AS-stabilized ZS (GZS) increases with increase of chloride content in soil samples. Friedel’s salt (Fs) and NaOH are generated by the reaction of NaCl and CaO·Al2O3 (CA) in the slag in the GZS. Fs can fill the pores in stabilized soil, and NaOH can promote calcium silicate hydrate (CSH) generation. These two effects combine to enhance the strength of GZS. The relationship between the rate of increase of 28-d UCS of AS-stabilized chloride saline soil and the chloride content in soil was obtained through regression analysis of the increase of UCS of GZS. 相似文献
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Gui-xiao La Ping Fang Yi-bo Teng Ya-juan Li Xian-yong Lin 《Journal of Zhejiang University. Science. B》2009,10(6):454-464
The effects of CO2 enrichment on the growth and glucosinolate (GS) concentrations in the bolting stem of Chinese kale (Brassica alboglabra L.) treated with three nitrogen (N) concentrations (5, 10, and 20 mmol/L) were investigated. Height, stem thickness, and
dry weights of the total aerial parts, bolting stems, and roots, as well as the root to shoot ratio, significantly increased
as CO2 concentration was elevated from 350 to 800 μl/L at each N concentration. In the edible part of the bolting stem, 11 individual
GSs were identified, including 7 aliphatic and 4 indolyl GSs. GS concentration was affected by the elevated CO2 concentration, N concentration, and CO2×N interaction. At 5 and 10 mmol N/L, the concentrations of aliphatic GSs and total GSs significantly increased, whereas those
of indolyl GSs were not affected, by elevated atmospheric CO2. However, at 20 mmol N/L, elevated CO2 had no significant effects on the concentrations of total GSs and total indolyl GSs, but the concentrations of total aliphatic
GSs significantly increased. Moreover, the bolting stem carbon (C) content increased, whereas the N and sulfur (S) contents
decreased under elevated CO2 concentration in the three N treatments, resulting in changes in the C/N and N/S ratios. Also the C/N ratio is not a reliable
predictor of change of GS concentration, while the changes in N and S contents and the N/S ratio at the elevated CO2 concentration may influence the GS concentration in Chinese kale bolting stems. The results demonstrate that high nitrogen
supply is beneficial for the growth of Chinese kale, but not for the GS concentration in bolting stems, under elevated CO2 condition.
Project (No. 2007CB109305) supported by the National Basic Research Program (973) of China 相似文献
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Yong NIE ;Xiao-jiang LIANG ;Mei-zhen LU ;Feng-wen YU ;Da-yong GU ;Min MIN ;Jian-bing JI 《浙江大学学报(A卷英文版)》2014,15(7):540-546
研究目的：研究方法：重要结论：确定氢氧化钠溶液化学吸收硫酰氟的传质反应动力学区域,建立增强因子模型。研究气液传质测定设备双搅拌釜中氢氧化钠溶液化学吸收硫酰氟的过程,并结合实验研究与理论分析建立了增强因子模型。基于氢氧化钠溶液化学吸收硫酰氟过程的实验研究,确定了氢氧化钠溶液化学吸收硫酰氟的传质反应动力学区域为快速拟一级反应。得到了298K下其二级反应速率常数为1．44m3／（mol·s）,并建立了增强因子模型E=68．08CBL1/2,为脱除熏蒸后残留硫酰氟的工业化应用提供了理论依据。 相似文献