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A suspension with good rheology and high stability is crucial for slip casting and gelcasting technology. However, a mixed suspension from two or more different powders usually has bad rheology because of the easy agglomeration of mixed powders caused by the attractive force between the powders with heterocharges. We studied the surface modification of the each single-component powders ( SiC, Al2O3, ZrO2(3 Y) powders) and the SiC- Al2O3- ZrO2(3 Y) mixed powders to increase the repulsive force by adjusting the pH value and adding polyacrylic acid ( PAA) as dispersant. The PAA addition effects on the SiC- Al2O3- ZrO2(3 Y) mixture were investigated in terms of zeta potential, pH range for heterocharge region, dispersion of the mixed powders and rheology of the mixed slurry based on the study of each unary suspensions. The results show that before surface modification the SiC- Al2O3- ZrO2(3 Y) mixed powders were agglomerated severely because they were in the heterocharge region with a broad pH range from 3.5 to 8.25, while after surface modification ( pH = 10.5, PAA = 0.8wt%) the heterocharge region was narrowed with a relatively narrower pH range from 2.6 to 3.7. The mixed powders with homocharges were dispersed well because of the great electrostatic repulsive force and steric hindrance offered by PAA and the mixed suspensions had favorable rheology. [ABSTRACT FROM AUTHOR]

Ordered mesoporous alumina (OMA)-supported vanadia catalysts with different vanadium loading (denoted as n V/OMA) were employed for ethylbenzene dehydrogenation to styrene with CO 2 as soft oxidant, and a commercial γ-Al 2 O 3 -supported vanadia catalyst for comparison. The catalytic behavior depends strongly on the vanadium loading and the support properties. With an optimal V loading of 0.8 mmol/g-support, 0.8 V/OMA catalyst exhibits superior catalytic performance than that of 0.8 V/γ-Al 2 O 3 , which can be attributed to the excellent structural, textual, and surface properties of OMA support. The important roles played by OMA lies in stabilizing highly dispersed V 5+ active species and preventing the coke formation. [ABSTRACT FROM AUTHOR]