Catalyst support made from porous local clay-fly ash composites for activated carbon materials

Porous ceramics has been extensively applied in many sectors, such as catalyst supports, heat exchanger, and adsorbents. From various fabrication techniques, polymer sponge replica technique is the most common method in fabricating porous ceramics. In this research, the compressive and bending strength of the porous samples at different clay fly ash ratios ( 1: 1 to 1 :2) were investigated. This study also investigated the influences of different amount of suspensions (50 to 70 wt.%) on the mechanical properties and their characteristics in developing porous ceramic composites. The porous ceramic composites were developed using polymer sponge replica technique. The interconnected microstructure of porous ceramic composites showed the compressive strength that can reach as high as 1.26 MPa with 94.5 vol.% porosity for clay-fly ash ratio of 1:1.5. The presences of fly ash cenospheres have significantly caused the formation of voids within struts and influence the compressive strength in porous ceramic composites. Although the porous ceramic composites (1: 1.5 ratio between clay and fly ash) has high compressive strength (1.26 MPa), its bending strength was only able to achieve 0.31 MPa. This is attributed to the unidirectional open cell formation of the porous ceramic composites. On the other hand, porous ceramic composites with clay-fly ash ratio of 1:2 have also achieved good compressive strength (1.12 MPa) and bending strength (0.79 MPa). Therefore, the porous ceramic composites with clay-fly ash ratio of 1 :2 at 70 wt. percent suspension was suitable for further process by applying a layer of carbon coating. Different amount of sucrose (5 to 15 wt.%) and fly ash-derived carbon (0 to 4 wt.%) were used in the coating process in order to understand the effectiveness of carbon coating on the surface of porous ceramic composites. The application of sucrose solution has acted as an adhesive and it provided an interlocking behaviour between the fly ash-derived carbon and the surface of porous ceramic composites. The sample with 4 wt.% of fly ash-derived carbon additions exhibited higher carbon formation as compared to 0 wt.%. This has shown that 15 wt.% sucrose with 4 wt.% fly ash-derived carbon obtained better carbon coating (14.8 wt.% total carbon content) and suitable to proceed for carbon activation. In order to determine the effectiveness of carbon activation, two microwave powers which consisted of 700 W (Watts) and 1000 W, along with various activation durations (1 0 to 30 minutes) were applied. The carbon activation process was assisted by potassium hydroxide (KOH) as activating agent. After activation process, the carbon layers are mainly consisted of amorphous carbon and graphite. The activation process also demonstrates that higher microwave power (1000 W) has produced better micropores distribution as compared to lower microwave power (700 W). Therefore, it has shown that porous ceramic composites are suitable to be applied as catalyst support for activated carbon materials.