Controlled Synthesis And Performance Of Ordered Large Mesoporous (Ce And W)-based Oxides With High Specific Surface Area

Ordered mesoporous metal oxides are widely used in medicine,sensing,catalysis and other fields due to their high specific surface area,rich pore structure,and structural characteristics of self-supporting structures.In this paper,a series of ordered large mesoporous cerium-based and tungsten-based metal oxides with high specific surface area,adjustable framework size and chemical composition are designed and synthesized,and their performance tests are performed.The effects of mesoscopic structure parameters(specific surface area,pore size distribution,pore wall thickness,and pore volume)and framework chemical composition on the adsorption and gas sensing performance of Cr(VI)were studied.A series of ordered mesoporous cerium oxides were synthesized using a series of mesoporous silica KIT-6 with different structures as templates and cerium nitrate hexahydrate as precursors by the nano-casting method.By adjusting the hydrothermal temperature of the KIT-6 template,the pore size and connectivity are gradually increased.Due to the use of asymmetric reverse replication strategy,the specific surface area of mesoporous cerium oxide was reduced from 155 m2/g to 128 m2/g.The adsorption test of chromium ions with mesoporous cerium oxide solutions with different concentrations found that the high specific ratio Cerium oxide with a large surface area has excellent adsorption performance for hexavalent chromium ions,and has the advantages of large adsorption amount and low residual concentration.The lowest hexavalent chromium ion in the solution can be adsorbed to 0.0017 mg/L,and the adsorption amount with 1000 mg/L as the initial concentration of the hexavalent chromium ion solution can reach 2976 mg/g.After kinetic analysis,the adsorption process is accurate.The second-order kinetic equation and the thermodynamic fitting result accord with the Freundlich adsorption model.A series of ordered mesoporous WO3/Co3O4 composites with different structural parameters were synthesized using a series of mesoporous silicon oxide KIT-6 with different structures as templates,silicon tungstic acid hydrate,and cobalt nitrate hexahydrate as precursors.The ordered mesoporous WO3/Co3O4 composites with high crystallinity and ordering specific surface area is(76?137 m2/g),and large mesopore diameter.Gas sensitivity test found that high specific surface area,ordered and large mesoporous cobalt oxide/tungsten oxide composites have high gas sensitivity and good selectivity to p-xylene gas:WO3/Co3O4-40 has a high sensitivity to p-xylene gas.The sensitivity is 7.3.Compared with pure phase tungsten oxide,which has excellent gas-sensitivity to hydrogen sulfide,the composite oxide has changed the selectivity of tungsten oxide material for gas.