Library

feed icon rss

Your email was sent successfully. Check your inbox.

An error occurred while sending the email. Please try again.

Proceed reservation?

Export
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Catalysis letters 55 (1998), S. 227-234 
    ISSN: 1572-879X
    Keywords: RhCl3 ; Co2(CO)8 ; SiO2 ; surface‐bonded Rh+(CO)2 ; highly active Rh–Co catalyst ; hydroformylation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The preparation of a highly active bimetallic SiO2‐supported Rh–Co catalyst from RhCl3 and Co2(CO)8 (Rh:Co= 1 : 3 atomic ratio) has been studied by IR spectroscopy and ethylene hydroformylation, etc. Two steps are involved in the preparative process: (1) surface‐mediated synthesis of Rh+(CO)2/SiO2 from calcined RhCl3/SiO2; (2) impregnation of Rh+(CO)2/SiO2 with a Co2(CO)8 solution followed by H2 reduction at 623 K. The IR results of reductive carbonylation of calcined RhCl3/SiO2 have been compared to those of uncalcined RhCl3/SiO2 at 373 K. In situ IR observations, extraction results and elemental analysis suggest that approximately 50% of RhCl3 are transformed to Rh2O3 on the SiO2 surface and that calcined RhCl3/SiO2 is converted to a mixture of [Rh(CO)2Cl]2 and [Rh(CO)2O2 (Os: surface oxygen) under CO at 373 K. When this SiO2‐supported mixture was submitted to impregnation with a Co2(CO)8 solution at room temperature, IR study and elemental analysis show that [Rh(CO)2Cl]2 reacts easily with Co2(CO)8 on the surface to give RhCo3(CO)12, whereas [Rh(CO)2O2 does not react with Co2(CO)8. Catalytic study in steady‐state ethylene hydroformylation shows that a catalyst thus derived is more active than a catalyst derived from RhCo3(CO)12/SiO2 and a catalyst derived by coimpregnation of [Rh(CO)2Cl]2 and Co2(CO)8 on SiO2. This result suggests that the high rhodium dispersion of [Rh(CO)2O2 plays a crucial role in the formation of highly dispersed bimetallic Rh–Co sites.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
  • 2
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Polymer International 41 (1996), S. 419-425 
    ISSN: 0959-8103
    Keywords: polyurethane ; cell growth ; phase separation ; hydrogen bonding index ; cytotoxicity ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Polyurethanes (PU) with suitable soft segments have been found to be good blood-compatible polymers and have attracted much attention recently. In this study, various molar amounts of 4,4′-methylene bisphenyl isocyanate reacted with poly(tetramethylene oxide) were synthesized to explore the optimal ratio of hard/soft segments for cell attachment and proliferation in in vitro systems. Differential scanning calorimetry and dynamic mechanical analysis were used to determine the physical properties, hydrogen bonding index (HBI) and transmission electron microscopy to observe the phase-separation phenomena in the materials, and 3T3 fibroblast to evaluate the dependence of the cell proliferation at 37°C on the material properties. Our results show that cell attachment and proliferation are closely related to the cell growth surface, which in turn is controlled by (1) the ratio of hard to total segment concentration and (2) the recrystallization temperature (Tc) of PU. To obtain a good cell growth surface, the ratio of hard to total segment concentration is found to be between 0.4 and 0.6, and HBI is between 1.5 and 2.1. Furthermore, when the Tc of PU is near the physiology temperature, a stable surface for cell growth can be provided. The shorter molecules in the soft segment region can rearrange the molecular chain at 37°C.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    Library Location Call Number Volume/Issue/Year Availability
    BibTip Others were also interested in ...
Close ⊗
This website uses cookies and the analysis tool Matomo. More information can be found here...