DEVELOPMENT OF CATALYST SUPPORT MATERIAL FROM PINDIGA BENTONITIC CLAY

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Department of Engineering

ABSTRACT
Catalyst support material was developed from Pindiga bentonitic clay using heat and acid treatment. Raw Pindiga elay was beneficiated using the wet method. The beneficiated clay was calcined at temperatures of 700°C, 750°C, and 800°C. Thereafter, the calcined clay samples were activated by acidifying with sulphuric acid, using wet acidification method at 95°C and dry acidification method at room temperature. The raw, beneficiated and acid treated clay samples were characterized using XRD, XRF and BET techniques. The XRD and XRF characterization results showed that the clay developed higher purity during beneficiation, calcinations and acidification as reflected by the decrease in organic impurities in form of carbon and graphite and reduction in quartz and soluble salts. The raw clay sample had very high iron impurity of up to 26.54 wt%. Only slight reduction in the iron content was observed after beneficiation and calcination but after acidification a reasonable reduction in the iron content was observed bringing the value to 12.80 wt% for 800°C calcined and wet acidified sample, and 15.34 wt% for 700°C calcined and wet acidified sample. Also, the BET characterization results showed that the clay developed larger surface area; the surface area of the raw clay which was 26.35 m7g increased to 43.81 m2/g after beneficiation, and to 97.31, 99.32 and 139.59 m2/g after calcination at 700°C, 750°C, and 800°C respectively. The surface area further increased to 191.41 and 270.44 m2/g after wet acidification of the 700°C, and 800°C calcined samples respectively. The largest surface area values of 364.73 and 404.48 m2/g were obtained for the 700°C, and 800°C calcined and dry acidified samples respectively. Based on the surface area, the materials calcined and acidified can be considered as suitable for catalyst support, literature values being between 150 and 350 m2/g for commercial montmorillonite clay suppors. The sample calcined at 800°C and wet acidified was considered the best support material on the basis of its lowest iron content of 12.80 wt% and high surface area of 270.44 m2/g.