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1.
The reaction of copper salts with AlPO4-5 or Vv-VAPO-5 under acidic (CuCl2, pH adjusted to 2) but especially basic conditions (Cu(NH3)
4
2+
, pH adjusted to 9) gives ion incorporations greater than expected by a simple ion exchange mechanism (both AlPO4-5 and Vv-VAPO-5 could be expected to have no cation exchange capacity). Ion incorporation is proposed to occur initially at defect sites, and examination of the ESR spectrum of a dehydrated, evacuated CuCl2-exchanged AlPO4-5 shows that these defect sites give rise to a number of unique environments upon CuII incorporation. The CuCl2-exchanged VAPO-5 retains a significant toluene accessibility to the Vv sites in the VAPO-5. However, the toluene accessibility in the Cu(NH3)
4
2+
-exchanged VAPO-5 is significantly reduced and we propose this is due to a combination of the presence of crystalline CuO and structural collapse from reaction with base (NH4OH). The ability of treatment with base (NH4OH, pH 13) to restrict access of toluene to the Vv sites of the original VAPO-5 was verified in a separate experiment. 相似文献
2.
A series of MoO3/AlPO4 catalysts with molybdena content varying from 2 to 16 wt% were prepared and characterized by low temperature oxygen chemisorption (LTOC), ammonia chemisorption, X-ray diffraction (XRD) and electron spin resonance (ESR). Maximum O2 uptake was observed at 6 wt% MoO3 loading indicating the completion of monolayer. The ESR results are in conformity with LTOC and XRD data. The activities of the catalysts were tested in methanol partial oxidation and are correlated with their surface characteristics wherever possible.IICT Communication No. 3188. 相似文献
3.
Nabarun Roy 《Progress in Polymer Science》2012,37(6):781-819
The various forms of carbon used in composite preparation include mainly carbon-black, carbon nanotubes and nanofibers, graphite and fullerenes. This review presents a detailed literature survey on the various modifications of the carbon nanostructures for nanocomposite preparation focusing upon the works published in the last decade. The modifications of each form of carbon are considered, with a compilation of structure-property relationships of carbon-based polymer nanocomposites. Modifications in both bulk and surface modifications have been reviewed, with comparison of their mechanical, thermal, electrical and barrier properties. A synopsis of the applications of these advanced materials is presented, pointing out gaps to motivate potential research in this field. 相似文献