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991.
《天然气化学杂志》2014,(6):795-800
Catalytic performances of the CO2 reforming of toluene on Co/MgO catalysts with different cobalt loadings were evaluated in a fluidized-bed reactor. The results showed that the conversion of toluene and the stability of Co/MgO increased, but the apparent reaction rate decreased at the initial stage with increasing the amount of metallic Co formed from the reduction of Co/MgO catalysts at 700 ~C. The deactivation of Co/MgO catalysts was mainly resulted from that a part of the metallic Co was oxidized by CO2 and could not be re-reduced by H2 at reaction temperature. Therefore, the excess metallic Co on the higher Co loading catalysts was beneficial to the catalyst stability. 相似文献
992.
993.
制备了高岭土修饰碳糊电极(KCPE),并以氢醌(HQ)为电催化介质测定还原型谷胱甘肽(GSH)。实验结果表明,在该电极上谷胱甘肽(GSH)的加入对氢醌的电化学响应有明显提高,且电催化氧化峰电流与GSH浓度呈良好的线性关系,由此可采用差分脉冲伏安法(DPV)对GSH进行定量测定。对修饰电极的电化学性能进行了表征,测得电极有效表面积为0.118 6 cm2、电荷传递系数为0.68、表观速率常数为1.08×104cm3·mol-1·s-1。在优化条件下,测得GSH在KCPE上的线性范围为0.1~1,2.5~25μmol/L,检出限为0.073μmol/L。用该方法对含GSH的市售药进行测定,结果满意。 相似文献
994.
采用简便的水热法,获得了具有氧化酶催化特性的二氧化锰纳米管,研究了其对氧气(O2)氧化3,3',5,5'-四甲基联苯二胺(TMB)发生显色反应的催化性能,重点考察了常见金属离子对其活性的抑制作用。结果表明,能与MnO2表面发生特异性吸附络合作用的Pb2+的抑制作用最为显著。基于该抑制作用,建立了针对铅离子的高灵敏、快速检测新方法。结果显示,铅的线性范围为1.0×10-7~1.0×10-3 mol/L,检出限为3.0×10-8 mol/L。 相似文献
995.
目的研究3种改性活性炭对菜地、河流底泥、荷花底泥镉吸附性的影响。方法对活性炭进行酸改性、碱改性和氧化改性,采用双硫腙分光光度法测定镉含量。结果对实验土样,最佳活性炭添加量为0.025 g/g。随着初始镉含量的升高,土壤对镉的吸附量不断增大。结论 3种改性活性炭相比普通活性炭对湿地土壤的镉吸附量均有不同程度的提升,荷花底泥中,酸性、氧化改性活性炭相比普通活性炭,吸附效果提高7.7%,8.3%,吸附效果提升显著。 相似文献
996.
Hiroyuki Muramatsu Kazunori Fujisawa Yong-Il Ko Kap-Seung Yang Takuya Hayashi Morinobu Endo Cheol-Min Yang Yong Chae Jung Yoong Ahm Kim 《催化学报》2014,35(6):864-868
Nanoscale defects in the outer tube to preserve the electrical and optical features of the inner tube can be engineered to exploit the intrinsic properties of double walled carbon nanotubes (DWCNTs) for various promising applications. We demonstrated a selective way to make defects in the outer tube by the fluorination of DWCNTs followed by the thermal detachment of the F atoms at 1000 °C in argon. Fluorinated DWCNTs with different amounts of F atoms were prepared by reacting with fluorine gas at 25, 200, and 400 °C that gave the stoichiometry of CF0.20, CF0.30, and CF0.43, respectively. At the three different temperatures used, we observed preservation of the coaxial morphology in the fluorinated DWCNTs. For the DWCNTs fluorinated at 25 and 200 °C, the strong radial breathing modes (RBMs) of the inner tube and weakened RBMs of the outer tube indicated selective fluorine attachment onto the outer tube. However, the disappearance of the RBMs in the Raman spectrum of the DWCNTs fluorinated at 400 °C showed the introduction of F atoms onto both inner and outer tubes. There was no significant change in the morphology and optical properties when the DWCNTs fluorinated at 25 and 200 °C were thermally treated at 1000 °C in argon. However, in the case of the DWCNTs fluorinated at 400 °C, the recovery of strong RBMs from the inner tube and weakened RBMs from the outer tube indicated the selective introduction of substantial defects on the outer tube while preserving the original tubular shape. The thermal detachment of F atoms from fluorinated DWCNTs is an efficient way to make highly defective outer tubes for preserving the electrical conduction and optical activity of the inner tubes. 相似文献
997.
提出了一个木质纤维素生物质预处理的全绿色加工过程.以玉米秸秆和玉米芯为原料,以超临界CO2和超声偶合法对木质纤维素进行预处理.超临界CO2预处理条件为:压力15-25 MPa,温度120170℃,含水量50%,反应时间0.54 h.超声场功率600W,温度80℃,作用时间2-8 h.用纤维素酶水解反应获得的还原糖总量来评价预处理效果.结果表明,单纯超临界CO2和超临界CO2偶合超声预处理都能够提高生物质水解反应还原糖产量.对于玉米芯,超临界CO2预处理(170℃,20 MPa,3 0min)后,还原糖产率为62%(未预处理的为12%).对于玉米秸秆(170℃,20 MPa,2.5 h),还原糖产率为46.4%.对于玉米芯,超临界CO2偶合超声预处理(600 W,80℃下超声处理6 h,然后用170℃,20 MPa超临界CO2预处理30 min)后,还原糖产率为87%.对于玉米秸秆,超临界CO2偶合超声预处理(600 W,80℃下超声处理8 h,然后用170℃,20 MPa超临界CO2预处理1 h)后,还原糖产率为25.5%.与未处理生物质相比,X射线衍射结果表明玉米秸秆和玉米芯在超临界CO2和超声预处理后其结晶度没有明显变化.扫描电镜分析则发现木质纤维素的表面积显著增加. 相似文献
998.
Systematic study on the electronic/geometrical structures and the parity alternation effect of silicon-doped ternary cationic clusters HCnSi2+(n = 1 ~9) have been carried out at the coupled cluster level. The ground-state (G-S) isomers of the clusters have been defined. The C, chains of the G-S isomers display polyacetylene-like structures. The even-n cations are more stable than the odd-n ones. Such a trend of even/odd alternation has been elaborated based on concepts of the bond character, atomic charge, incremental binding energy, ionization potential, proton affinity and fragmentation energies of the systems. The findings accord with the relative intensities of HC,,Si2+ species recorded in the related mass spectrometric experiments. 相似文献
999.
A supercritical carbon dioxide(Sc CO2) assisted phase inversion was developed to produce microporous poly(vinylidene fluoride)(PVDF) membranes whose morphology characteristics arise from both liquid-liquid demixing and solid-liquid demixing(crystallization). This result was confirmed by Fourier transform infrared spectroscopy(FTIR), from which both α and β crystals were found. As revealed by contact angle experiment, the PVDF membranes prepared via Sc CO2 assisted phase inversion were more hydrophobic compared with the control membrane produced via conventional immersionprecipitation technique. In particular, the sample with 15 wt% PVDF prepared at 45 °C and 13 MPa exhibited a contact angle of 142°, which was mainly caused by the multilevel micro- and nano- structure. The effects of polyethylene glycol(PEG), polyvinyl pyrrolidone(PVP) and lithium chloride(Li Cl) on the structures and crystal form were investigated. PVP promoted the formation of β phase crystal form, while PEG boosts the evolution of α phase. Li Cl restrained the crystallization degree of PVDF membrane under Sc CO2. 相似文献
1000.
CO2-expanded liquid (CXL) is a mixture of organic solvent with high-pressure CO2 whose volume is increased by CO2 dissolved in it. CXLs have attracted attention as tunable solvents, because the solvent properties can be widely controlled by the pressure. The volume expansion and the solubility of CO2 were measured by near-infrared spectroscopy for 6 CXLs at various pressures up to 55 bar and 40 °C. The molarity of organic solvent was determined from the absorbance of the 3ν and 2ν + δ bands, and that of CO2 was obtained from the area of the 3ν3 band, whose peak shifted to higher frequency with increasing pressure due to a decrease in the molecular interaction around CO2. The expansion coefficient was shown to be an increasing function of the pressure with larger slope at higher pressure, and the mole fraction of CO2 in the liquid phase was an almost linearly increasing function of the pressure. The results were in quantitative agreement with the literature data measured by conventional sampling method, indicating the validity of the spectroscopic method. 相似文献