Wasinton Simanjuntak

Effect of alumina addition on the phase transformation and crystallisation properties of refractory cordierite prepared from amorphous rice husk silica

Abstract The effect of alumina addition of 5–30% by weight on phase transformation and crystallisation properties of refractory cordierite ceramics prepared from amorphous rice husk silica followed by sintering treatment at temperature of 1230 °C was studied. The crystallinity and microstructure of the samples were characterised using X-ray diffraction (XRD) coupled with Rietveld analysis, scanning electron microscopy (SEM), respectively. Some physical properties include density, porosity, hardness, bending strength, and thermal expansion coefficient of the samples with different alumina additions were measured. The results show that addition of alumina promoted crystallisation of cordierite into crystalline spinel, corundum, cristobalite, in which with addition of 10–30% alumina, the cordierite phase was practically undetected. Addition of alumina was also found to increase the amount of spinel, while corundum and cristobalite decreased following alumina addition of 10–30%. The presence of spinel, corundum, and cristobalite resulted in increased of density, hardness, bending strength and thermal expansion coefficient, while for porosity, the opposite was observed. Thermal expansion coefficient of the samples with alumina addition of 15–30% reach the relatively constant value of 9.5 × 10−6/°C, with the main crystalline phase was spinel, accompanied by corundum and cristobalite in smaller quantities.

Hydrocarbon Rich Liquid Fuel Produced by Co-pyrolysis of Sugarcane Bagasse and Rubber Seed Oil Using Aluminosilicates Derived from Rice Husk Silica and Aluminum Metal as Catalyst

In this investigation, a mixture of sugarcane bagasse and rubber seed oil was subjected to pyrolysis for liquid fuel production, using aluminosilicates with different Si/Al ratios as catalysts prepared from rice husk silica and aluminum metal by electrochemical method. A series of pyrolysis experiments was conducted at the temperature range of 250 to 500 oC, with the main purpose to investigate the effect of the Si/Al ratios of the catalysts on the chemical composition of liquid fuels produced. The liquid fuels produced were analyzed using gas chromatography-mass spectrometry (GC-MS) technique for component identification. The experimental results show that the most intense production of liquid took place at the temperature range of 350 to 480 oC, while at lower temperatures gaseous product emerged as the main product. Analysis of the product using GC-MS technique revealed the presence of a series of compounds in the liquids, and broadly belongs to hydrocarbon, alcohol, ester, ketone, aldehyde, and acid. The results display significant effect of the catalyst composition on the composition of the liquids. The main trend observed is the tendency of increased the hydrocarbon content with decreased the Si/Al ratio of the catalyst, down to the ratio of 2.3 which produced liquid fuel with the highest hydrocarbon content 86%.