全文获取类型
收费全文 | 118篇 |
免费 | 5篇 |
国内免费 | 78篇 |
专业分类
化学 | 195篇 |
综合类 | 1篇 |
物理学 | 5篇 |
出版年
2023年 | 1篇 |
2022年 | 2篇 |
2020年 | 4篇 |
2019年 | 2篇 |
2018年 | 4篇 |
2017年 | 7篇 |
2016年 | 10篇 |
2015年 | 6篇 |
2014年 | 5篇 |
2013年 | 3篇 |
2012年 | 18篇 |
2011年 | 11篇 |
2010年 | 9篇 |
2009年 | 8篇 |
2008年 | 9篇 |
2007年 | 9篇 |
2006年 | 7篇 |
2005年 | 18篇 |
2004年 | 13篇 |
2003年 | 7篇 |
2002年 | 4篇 |
2001年 | 4篇 |
2000年 | 4篇 |
1999年 | 13篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 3篇 |
1994年 | 3篇 |
1992年 | 6篇 |
1991年 | 2篇 |
1989年 | 1篇 |
1984年 | 1篇 |
排序方式: 共有201条查询结果,搜索用时 93 毫秒
101.
Deep hydrodesulfurization (HDS) of sterically hindered sulfur compounds in gas oils will require enhanced hydrogenation activity to hydrogenate the aromatic rings of the sulfur compounds. Although H2S is known to inhibit the direct HDS route for most of the sulfided catalysts, its promotion to the hydrogenation and subsequent HDS was newly observed for unsupported MoS2. This promotion suggests that ultra deep HDS over sulfide catalysts can be achieved along with high metal loading, minimal support-metal interactions and optimal dependence on the Ni species. On the other hand, the strong hydrogenation activity of sulfur-tolerant noble metal catalysts suggests that ultra deep HDS as well as deep aromatics saturation can be achieved. This paper discusses recent catalytic approaches for ultra deep HDS using conventional sulfide catalysts and/or noble metal catalysts, such as the newly developed Pd-Pt/Yb-USY zeolite catalyst. 相似文献
102.
Radostina PALCHEVA Luděk KALUZA Alla SPOJAKINA Květue JIRTOV Georgi TYULIEV 《催化学报》2012,33(6):952-961
A hydrotreating NiMo/γ-Al2O3 catalyst(12 wt% Mo and 1.1 wt% Ni) was prepared by impregnation of the support with the Anderson-type heteropolyoxomolybdate(NH4)4Ni(OH)6Mo6O18.Before impregnation of the support,it was modified with an aqueous solution of H3BO3,Co(NO3)2,or Ni(NO3)2.The catalysts were investigated using N2 adsorption,O2 chemisorption,X-ray diffraction,UV-Vis spectroscopy,Fourier transform infrared spectroscopy,temperature-programmed reduction,temperature-programmed desorption,and X-ray photoelectron spectroscopy.The addition of Co,Ni,or B influenced the Al2O3 phase composition and gave increased catalytic activity for 1-benzothiophene hydrodesulfurization(HDS).X-ray photoelectron spectroscopy confirmed that the prior loading of Ni,Co or B increased the degree of sulfidation of the NiMo/γ-Al2O3 catalysts.The highest HDS activity was observed with the NiMo/γ-Al2O3 catalyst with prior loaded Ni. 相似文献
103.
采用水热法制备了复合氧化物TiO2-Al2O3,研究了水热温度、反应物浓度、聚乙二醇(PEG)平均分子量和浓度对所制样品结构和织构性质的影响,并用X射线衍射、N2吸附-脱附、热重-差热分析、NH3程序升温脱附、吸附吡啶的红外光谱和程序升温还原技术对TiO2-Al2O3及其负载的NiMoP催化剂进行了表征,在中压固定床微反装置上考察了催化剂上FCC柴油的加氢脱硫性能.结果表明,随着水热温度、反应物浓度、PEG分子量和浓度的提高,所制TiO2-Al2O3复合氧化物的比表面积和孔体积均有所提高,在优化的制备条件下分别可高达266m2/g和0.58cm3/g,其负载的NiMoP催化剂的比表面积也高达175m2/g,且其酸性较弱,以L酸为主.由于NiMoP/TiO2-Al2O3催化剂中TiO2的存在降低了活性组分与载体间的强相互作用,使其催化FCC柴油加氢脱硫活性比NiMoP/Al2O3催化剂的高. 相似文献
104.
105.
106.
A simple method for preparation of presulfided eggshell CoMoS/γ-Al2O3 catalysts with sharp boundary is developed, through which the eggshell thicknesses of Co and Mo could be easily regulated by controlling the impregnation time. According to the results characterized by EDS, XRD, HRTEM and FT-IR of adsorbed CO, the active component structures, the nature and/or the amount of active sites on the eggshell catalyst are similar to these on the uniform catalyst. The evaluation results of the catalytic performance in selective hydrodesulfurization (HDS) of FCC gasoline show the presence of significant internal diffusion inhibition effect on HDS of S-compounds especially in the uniform catalyst. Compared with uniform catalyst, the eggshell catalyst could remarkably reduce such an internal diffusion inhibition effect due to a shortened diffusion path of the reactants, thus showing higher HDS activity and selectivity. 相似文献
107.
以磷酸氢二铵为磷源,硝酸镍为镍源,硝酸铝为助剂铝源,制备了nP/nNi=0.8,Al含量为1.06wt%~6.35wt%的一系列Al-Ni2P/SBA-15催化剂。采用XRD、TEM和N2吸脱附等技术对催化剂的结构进行了表征研究,以二苯并噻吩(DBT)作为模型化合物,在微型固定床反应器上对催化剂的加氢脱硫(HDS)性能进行了评价。结果表明,Al修饰的Al-Ni2P/SBA-15催化剂仍然保持介孔结构,当Al含量低于5.29wt%时,催化剂的物相主要是Ni2P,当Al含量在5.29wt%-6.35wt%之间时,催化剂的物相为Ni2P和Ni12P5。Al含量为4.24wt%的3-Al-Ni2P/SBA-15催化剂具有最好的二苯并噻吩加氢脱硫催化活性,在反应温度为360 ℃,反应压力为3.0 MP的条件下,3-Al-Ni2P/SBA-15催化剂对二苯并噻吩的转化率可达99.0%。 相似文献
108.
SK Corporation of Korea has developed a unique process, SK hydrodesulfurization (HDS) pretreatment technology, to produce ultralow sulfur diesel (ULSD) with pretreatment of the middle-distillate-range petroleum fractions. This technology has been successfully demonstrated through a 1000 barrel/day (B/D) demonstration plant, which has been running since May 2002. This technology is based on the adsorptive removal of a small amount of nitrogen-based natural polar compounds (NPC). Dramatic improvement in deep HDS efficiency is observed with the removal of NPC from the feedstock.SK HDS pretreatment process consists of multiple adsorbers, two stripping columns for desorbent recovery, associated pumps, and overhead system. Middle distillate feed is pretreated prior to HDS process in the adsorbent vessels followed by stripping to remove a small amount of desorbent. The pretreated is then sent to the downstream HDS unit for sulfur removal. The rejected stream with high nitrogen content, about 2vol%, can be either used as a blending stock for heavy petroleum products or processed in other refining units.This paper describes the fundamental principle of the process, discusses the case study results with various feedstocks and operation conditions in pilot plant and demonstration plant, and provides economic assessment data. 相似文献
109.
Molybdenum HDS catalysts supported on niobia-silica 总被引:1,自引:0,他引:1
Sonia Damyanova Stanislava Andonova Iskra Stereva Chavdar Vladov Lachezar Petrov Paul Grange 《Reaction Kinetics and Catalysis Letters》2003,79(1):35-42
The effect of the amount of Nb2O5on the dispersion and reductive properties of Mo/Nb2O5-SiO2 catalysts has been studied. Addition of niobium leads to an increase of the dispersion, and the reducibility of molybdenum.
A synergetic effect of niobium on the catalytic activity in hydrodesulfurization of thiophene was observed at 5.4 wt.% of
Nb2O5.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
110.
Zeinab Hajjar Mohammad Kazemeini Shokoufe Tayyebi 《Phosphorus, sulfur, and silicon and the related elements》2016,191(9):1256-1261
A Co-Mo/graphene oxide (GO) catalyst has been synthesized for the first time for application in a defined hydrodesulfurization (HDS) process to produce sulfur free naphtha. An intelligent model based upon the neural network technique has then been developed to estimate the total sulfur output of this process. Process operating variables include temperature, pressure, LHSV and H2/feed volume ratio. The three-layer, feed-forward neural network developed consists of five neurons in a hidden layer, trained with Levenberg–Marquardt, back-propagation gradient algorithm. The predicted amount of residual total sulfur is in very good agreement with the corresponding experimental values revealing a correlation coefficient of greater than 0.99. In addition, a genetic algorithm (GA) has been employed to optimize values of total sulfur as well as reaction conditions. 相似文献