Key Engineering Materials Vol. 757

Abstract: This research focused on the bioethanol production from rice husk via enzymatic hydrolysis and fermentation of glucose product. Rice husks were ball-milled, alkali pretreated with 2 %(w/v) NaOH for 3 hours and regenerated by N-methylmorpholine N-oxide (NMMO)/H₂O solution into Cellulose II structure. These processes were aimed to enhance the surface purity area and accessibility of enzyme, respectively. Rice husks were hydrolyzed with cellulase from Trichoderma reesei ATCC 26921 at various concentrations ranging from 10 to 40 FPU/g of rice husk. The maximum yields of glucose from alkali pretreated rice husk, ball-milled rice husk of sieve size 45-75 μm and regenerated rice husk were 7.13, 9.52 and 10.36 mg/mL, respectively. This was conducted at the enzyme concentration of 20 FPU/g of rice husk for 48 hours. The glucose product was fermented by using Saccharomyces cerevisiae Safale US-05 at various concentrations ranging from 10 to 70 %(v/v). The maximum yields of ethanol products at 50 %(v/v) of yeast and 48 hours of fermentation from the alkali pretreated rice husk, ball-milled rice husk of sieve size 45-75 μm and regenerated rice husk were 44.36%, 68.79% and 89.11% of glucose respectively. The greater yield may be arise from an increase in surface area and the swollen cellulose structure of rice husk.

Abstract: Palm oil is considered as a potential feedstock for biofuel production in Thailand due to its property and availability. In recent years, there has been an increased attention on upgrading of palm oil to biofuels using various technologies. One of the most promising technologies is pyrolysis, in which palm oil is heated at the temperature in the range of 400 to 500 °C under oxygen-free atmosphere. In the present study, the uncoated catalyst and coated catalyst pyrolysis processes of palm oil for biofuel production in a continuous flow microchannel reactor were investigated with various catalyst types (MgO, Al₂O₃) at 400-500 °C, 2 ml/hr palm oil flow rate, and 0.1 g of catalysts. Liquid product yield, solid product yield and gaseous product yield were determined. The obtained results revealed that the high triglyceride conversion could be achieved at a short reaction time in microchannel reactor, which attributed to the enhancement of both heat and mass transfer. The pyrolysis liquid products composed of hydrocarbons, free fatty acids, and other oxygenated compounds which are the results of triglyceride cracking. Furthermore, product selectivity of palm oil pyrolysis depended on temperature and catalyst type.

Abstract: High temperature water gas shift (HT-WGS) is an important catalytic process connected with reforming process in hydrogen production. Ni/CeO₂-Al₂O₃ (or Al₂O₃) catalysts were studied in this work on the effect of catalyst preparation method toward the physicochemical properties and the HT-WGS activity. Ni/CeO₂-Al₂O₃ were prepared by sol-gel and impregnation methods whereas Ni/Al₂O₃ was prepared by impregnation method. The catalyst samples were characterized by XRD, H₂-TPR and H₂-TPD techniques. The catalytic activities of HT-WGS catalysts was demonstrated at 550°C, GHSV of 2x10⁵ mLh^-1gcat^-1and steam-to-CO ratio of 3. Nickel was detected as a nickel aluminate phase in the calcined catalyst. Ni strongly interacted with support in the calcined catalyst prepared by sol-gel method. The strong metal-support interaction can be resisted by preparing catalyst via impregnation and CeO₂ can promote the H₂O dissociation in HT-WGS mechanism. The highest metal dispersion, largest metal surface area and greatest HT-WGS activity were consequently achieved by Ni/CeO₂-Al₂O₃ prepared from impregnation method.