Apanee Luengnaruemitchai

Comparative studies of low-temperature water-gas shift reaction over Pt/CeO2, Au/CeO2, and Au/Fe2O3 catalysts

We studied catalytic low-temperature water–gas shift (WGS) reaction over the Pt=CeO2 ,A u=CeO2 and Au=Fe2O3 catalysts. The activity of these catalysts was tested in the composition of 4% CO, 2.6–20% H2O and helium in the range of 120–360 C. It was found that CO and H2O concentrations have significant effects on the catalytic activity. The 1% Pt=CeO2 was substantially more active than other catalysts in the presence of 20% H2O. The catalytic activity of these catalysts was compared in the presence of H2 and deactivation test was also performed. BET, XRD, SEM and TEM analyses give additional information on the morphological structure of investigated samples. 2003 Elsevier Science B.V. All rights reserved.

Release of monomeric sugars from Miscanthus sinensis by microwave-assisted ammonia and phosphoric acid treatments.

Microwave-assisted ammonium hydroxide (NH4OH) followed by phosphoric acid (H3PO4) treatments were used to release monomeric sugars from Miscanthus sinensis grown in Cha-Chueng-Sao province, Thailand. Treatment with 1.0% (w/v) NH4OH, 15:1 liquid-to-solid ratio (LSR) at 120 °C temperature for 15 min liberated 2.9 g of monomeric sugars per 100 g of dried biomass, whereas the corresponding yield for a treatment with 1.78% v/v H3PO4, 15:1 LSR at 140 °C for 30 min was 62.3 g/100 g. The two-stage pretreatment, treatment with NH4OH at 120 °C temperature for 15 min followed by treatment with H3PO4 at 140 °C for 30 min, impressively provided the highest total monomeric sugar yield of 71.6 g/100 g dried biomass.

Activity and basic properties of KOH/mordenite for transesterification of palm oil

Abstract The catalytic performance of KOH/mordenite has been studied for transesterification of palm oil using a batch reactor and a packed-bed reactor at 60 °C and atmospheric pressure. The KOH/mordenite processed transesterification in the batch reactor gave the highest methyl ester yield of 96.7% under optimum conditions, while a methyl ester content over 94.5% was obtained in the packed-bed reactor. This comparison indicates that transesterification in a batch-type reactor gives a higher methyl ester yield than that of a continuous-flow reactor. Dealumination was found in the calcined catalysts and had a significant effect on the physical structure and chemical composition of the catalysts. Leaching of the potassium species was negligible, whereas depositing and washing of the reacted mixture with acetone on the catalyst surface were observed by FTIR.

Efficient process for ethanol production from Thai Mission grass (Pennisetum polystachion).

Mission grass (Pennisetum polystachion) obtained from Tak Province, Thailand, possesses the potential to become a lignocellulosic biomass for bioethanol production. After the grass underwent milling and alkaline pretreatments, it was subjected to acid and enzymatic hydrolysis. The glucose hydrolyzate from the grass was detoxified to remove inhibitory compounds and degradation products such as furfural and 5-hydroxymethylfurfural. Overliming at pH 10 produced the highest ethanol yield. Among various strains of bakers yeasts, Saccharomyces cerevisiae TISTR 5596 with a yeast concentration of 10% v/v produced the maximum ethanol yield at 16 g/L within 24h, which is among one of the fastest ethanol producing microorganisms compared to other strains of S. cerevisiae as well as other ethanol-producing microorganisms.

Enhanced butanol production by immobilized Clostridium beijerinckii TISTR 1461 using zeolite 13X as a carrier

Butanol production by cell immobilization onto porous materials-brick and zeolite 13X-was investigated using Clostridium beijerinckii TISTR 1461. Characterization results of two materials were completed to evaluate their potential as an immobilization carrier. Although zeolite has greater porosity than brick, it cannot be used for cell aggregation without treating with chemical. After immobilization, both materials can enhance butanol titers from 5.29 to 5.80g/L and 8.58g/L using brick and zeolite, respectively. Butanol to glucose yield also improved from 0.14 to 0.16g/g after immobilization. It was found that butanol production significantly increased due to an increase in buffering capacity, strong bonding between the zeolite surface and cell, and butanol tolerance. In addition, repeated batch fermentation was performed, demonstrating that cells immobilized onto zeolite 13X have high stability and potential for long-term use in continuous fermentation.

Capability of Thai Mission grass (Pennisetum polystachyon) as a new weedy lignocellulosic feedstock for production of monomeric sugar

Mission grass (Pennisetum polystachyon) grown in Pakchong District, Nakornratchasima Province, Thailand, with high cellulose and hemicellulose contents were harvested to determine the fermentable monomeric sugars for bioethanol production by two-stage microwave/chemical pretreatment process. Microwave-assisted NaOH pretreatment effectively removed approximately 85% lignin content in Mission grass, using 3% (w/v) NaOH, 15:1 liquid-to-solid ratio (LSR) at 120 °C temperatures for 10 min. As a result, in the second stage, microwave-assisted H2SO4 pretreatment of an alkaline-pretreated Mission grass solid releasedan impressively high fermentable sugar content (34.3±1.3 g per 100 g of dried biomass), consisting mainly of 31.1±0.8 g of glucose per 100 g of dried biomass, using 1% (w/v) H2SO4, 15:1 LSR at 200 °C temperature for a very short pretreatment time (5 min). The total monomeric sugar yield obtained via two-stage microwave/chemical process was 40.9 g per 100 g of dried biomass.

Synthesis and characterization of M-MCM-48 (M = Cr, Ce) from silatrane via sol–gel process

Chromium and cerium incorporated into MCM-48 framework are hydrothermally synthesized via sol–gel process without any additives and characterized by X-ray diffraction, N2 adsorption/desorption, Scanning electron microscopy (SEM), Transmission electron microscopy (TEM), Diffuse reflectance UV–vis spectroscopy, and Thermogravimetric analysis. Results indicate that the materials possess a long-range ordered structure, high specific surface area, and narrow pore size distribution. SEM images illustrate the edge-truncated octahedron morphology of Cr-MCM-48 while Ce-MCM-48 preserves the truncated octahedron of the MCM-48 parent material. TEM images show the pore network of Ia3d symmetry after loading metals. Spectroscopic data confirm the existence of metals in the framework and extra-framework. At low Cr content, Cr-MCM-48 contains only Cr(VI) species while rich Cr content loading results in both the Cr(VI) and Cr(III) species. The hydrothermal stability of MCM-48 is enhanced by carefully incorporating metals into the parent material.

Effect of Phosphoric Acid Pretreatment of Corncobs on the Fermentability of Clostridium beijerinckii TISTR 1461 for Biobutanol Production

Corncobs pretreated with H2SO4, HNO3, and H3PO4 were compared to evaluate the fermentation ability of Clostridium beijerinckii TISTR 1461 to produce biobutanol via acetone–butanol–ethanol (ABE) fermentation. It was found that the hydrolysate from H3PO4 pretreatment could be used as a substrate without any inhibitor removal methods. However, in terms of sugar yield, it gave the lowest total sugars in both pretreatment and enzymatic hydrolysis. Response surface methodology was applied to optimize enzymatic hydrolysis of the pretreated corncobs. The optimized conditions reduced the consumption of enzymes and hydrolysis time to 7.68 FPU/g biomass and 63.88 hr, respectively, and yielded 51.82 g/L reducing sugars. The Celluclast 1.5 L and Novozyme 188 enzyme ratio were varied to maximize the hydrolyzed sugars. The ABE fermentation, using substrate from phosphoric acid pretreatment of corncobs, with 10 g/L glucose supplementation produced 11.64 g/L of total ABE, which was close to the control experiment using synthetic medium. This study showed that corncobs pretreated with phosphoric acid could potentially be used as a substrate without using a detoxification process.

Production of biobutanol from acid-pretreated corncob using Clostridium beijerinckii TISTR 1461: Process optimization studies

ABSTRACT Corncob is a potential feedstock in Thailand that can be used for fermentable sugar production through dilute sulfuric acid pretreatment and enzymatic hydrolysis. To recover high amounts of monomeric sugars from corncob, the sulfuric pretreatment conditions were optimized by using response surface methodology with three independent variables: sulfuric acid concentration, temperature, and time. The highest response of total sugars, 48.84 g/L, was found at 122.78°C, 4.65 min, and 2.82% (v/v) H2SO4. With these conditions, total sugars from the confirmation experiment were 46.29 g/L, with 5.51% error from the predicted value. The hydrolysate was used as a substrate for acetone–butanol–ethanol fermentation to evaluate its potential for microbial growth. The simultaneous saccharification and fermentation (SSF) showed that C. beijerinckii TISTR 1461 can generate acetone–butanol–ethanol products at 11.64 g/L (5.29 g/L acetone, 6.26 g/L butanol, and 0.09 g/L ethanol) instantly using sugars from the hydrolysed corncob with Novozymes 50013 cellulase enzyme without an overliming process.

Evaluation of highly efficient monomeric sugar yield from Thai Tiger grass (Thysanolaena maxima)

Tiger grass (Thysanolaena maxima) is considered an important perennial energy crop in Southeast Asia with a high productivity and a low requirement for fertilizer. The monomeric sugar yield from T. maxima by two-stage microwave/chemical pretreatment and enzymatic hydrolysis is evaluated. The optimal conditions of the pretreatment were investigated by varying reaction times, reaction temperatures and chemical concentrations to maximize the amount of obtained monomeric sugar. The T. maxima was treated with microwave-assisted NaOH pretreatment using 15:1 liquid-to-solid ratio (LSR), 1% (w/v) NaOH at 140 °C for 15 min, followed by microwave-assisted H2SO4 pretreatment using 15:1 LSR, 0.5% (w/v) H2SO4 at 200 °C for 5 min. The maximum monomeric sugar released was 30.2 g/100 g of NaOH-pretreated solids. The enzymatic hydrolysis of the microwave-/chemical-pretreated T. maxima at pH 4.8, 45 °C for 120 h using enzyme amount of 160 μl/g pretreated solids produced an impressive maximum sugar yield of 110.4 g/100 g of NaOH-pretreated solids.