Submicrometer-sized, spherical vaterite particles were synthesized by solid-state reaction at room temperature in the presence of poly(acrylic acid)(PAA). The obtained products were characterized by XRD, IR and SEM. I...
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Submicrometer-sized, spherical vaterite particles were synthesized by solid-state reaction at room temperature in the presence of poly(acrylic acid)(PAA). The obtained products were characterized by XRD, IR and SEM. It was revealed that with increasing PAA amount, the crystal polymorph of CaCO 3 particles varied gradually from pure calcite through a mixture of calcite and vaterite to pure vaterite, and the particle size decreased generally. It was proposed that in solid-state reaction, PAA induced the formation of vaterite and the phase transformation from vaterite to calcite was prevented completely due to the absence of H 2O, resulting in the formation of pure vaterite particles.
As an example on how to understand the catalytic sites at the molecular level by starting with the model catalysts,this report briefly describes three Re-Sn mixed oxide crystallites with well-defined structures and th...
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As an example on how to understand the catalytic sites at the molecular level by starting with the model catalysts,this report briefly describes three Re-Sn mixed oxide crystallites with well-defined structures and their catalytic performances in the selective ammoxidation of light *** specific crystalline（100） structures of SbRe2O6 and their interaction with the NH3 reactant play a crucial role in the activation of C-H bonds in alkane *** interaction between the（100） planes and NH3 leads to the formation of adsorbed NHx species and oxygen vacancies,and it specially increases the activity of the lattice oxygen atoms,which constitute the active sites for the C-H bond activation in the ammoxidation *** provides useful information for the design of novel catalysts of the selective oxidation reactions.
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