Optimization of alkaline peroxide pretreatment of rice straw

Lignocellulose represents a promising starting material for conversion to fuels and chemicals in biorefinery; however, its efficient conversion to sugar requires a prerequisite pretreatment step. In the present research, the pretreatment of rice straw by alkaline peroxide pretreatment was studied aiming to enhance enzymatic digestibility of the cellulose-enriched solid. The alkaline hydrogen peroxide (AHP) pretreatment of rice straw using different concentration of hydrogen peroxide, reaction time, temperature, and solid loading were evaluated based on enzymatic digestibility and sugar recovery. The highest reducing sugar recovery was in the range of 499±6 mg/g native biomass after pretreatment using 2.5% H2O2 (v/v) at 35 ?C for 24 h and 7.5% biomass loading (w/v) after enzymatic hydrolysis using 20 FPU/g Accellerase® 1500. The work demonstrates the potential of the developed process for low temperature pretreatment of biomass for further conversion to value-added products.   Keywords: rice straw, biorefinery, alkaline peroxide pretreatmen

Transient Modeling of Tubular-Designed IIR-SOFC Fueled by Methane, Methanol, and Ethanol

It is known that the heating rate during starting-up of Solid Oxide Fuel Cell (SOFC) plays an important role of system performance and lifetime. In the present work, an axial 2-D tubular Indirect Internal Reforming SOFC (IIR-SOFC) model fueled by methane, methanol, and ethanol was developed with the aim of predicting the system temperature gradient during the starting-up period. All predicted results was calculated by using COMSOL®. The system was also compared with typical SOFC fueled by hydrogen. It was found that hydrogen heating gas required the lowest time to achieve the steady state (around 2 minutes) with the highest heating rate 0.93 K/s, which is not compatible for the thermal stress of SOFC material. The uses of methane, methanol, and ethanol as primary fuel can enhance compatible heating rate with the cell material, from which IIR-SOFC fueled by methanol is the best option in terms of its slow heating rate and high system efficiency. It is noted that the effects of inlet steam/carbon (S/C) ratio and gas flow pattern were also studied. It was observed that changing in S/C ratio is not significantly influence to temperature behaviors of the system. Meanwhile, IIR-SOFC with co-flow pattern provided smoother temperature gradient along cell and higher power density at steady state condition than that with counter-flow pattern.It is known that the heating rate during starting-up of Solid Oxide Fuel Cell (SOFC) plays an important role of system performance and lifetime. In the present work, an axial 2-D tubular Indirect Internal Reforming SOFC (IIR-SOFC) model fueled by methane, methanol, and ethanol was developed with the aim of predicting the system temperature gradient during the starting-up period. All predicted results was calculated by using COMSOL®. The system was also compared with typical SOFC fueled by hydrogen. It was found that hydrogen heating gas required the lowest time to achieve the steady state (around 2 minutes) with the highest heating rate 0.93 K/s, which is not compatible for the thermal stress of SOFC material. The uses of methane, methanol, and ethanol as primary fuel can enhance compatible heating rate with the cell material, from which IIR-SOFC fueled by methanol is the best option in terms of its slow heating rate and high system efficiency. It is noted that the effects of inlet steam/carbon (S/C) ratio and gas flow pattern were also studied. It was observed that changing in S/C ratio is not significantly influence to temperature behaviors of the system. Meanwhile, IIR-SOFC with co-flow pattern provided smoother temperature gradient along cell and higher power density at steady state condition than that with counter-flow pattern

Study of Liquid Alkanes Production from Biomass-Derived Carbohydrates by Aldol-Condensation and Hydrogenation Processes

This research aims to synthesis liquid alkanes from biomass-derived hydroxyl methyl furfural (HMF) and furfural by aldol-condensation and hydrogenation processes over several catalysts i.e. TiO2, TiO2-ZrO2, Pd/Al2O3 and Pd/CeO2. It was found that the catalysts make significant impact on the selectivity and yield of alkanes product. It is noted that Pd/Al2O3 provided the highest alkane yield and selectivity. The aldol-condensation and hydrogenation of HMF over Pd/Al2O3 provide high C12 selectivity whereas the aldol-condensation and hydrogenation of furfural over Pd/Al2O3 provide high C8 selectivity. The effects of reaction temperature, reaction pressure and reaction time were then studied. The effect of inlet furfural to acetone molar ratio was also determined. It was also found that the optimized conditions to maximize the yield of alkane production from the aldol-condensation/hydrogenation of HMF and furfural are (i) at 53oC and 24 hr for aldol-condenstation of HMF, (ii) 80oC and 24 hr for aldol-condenstation of furfural, and (iii) 120oC for 6 hr with HMF to acetone molar ratio of 3:1 and furfural to acetone molar ratio of 4:1 in the presence of Pd/Al2O3 (calcined at 500oC) for hydrogenation reaction

Catalytic Conversion of Wastewater from Starch Industry to Levulinic Acid

Levulinic acid is known as versatile building block for the production of energy and various petrochemical products. In this present work, levulinic acid was produced by dehydration and rehydration of sugar-rich wastewater containing H2SO4 from starch industry. This study proposed feasibility of utilizing waste water that obtained from nano-crystalline process of starch factory as resource for the production of levulinic acid without catalyst adding. The influence of reaction time and reaction temperature to yield of levulinic acid were investigated. It was found that the highest yield of levulinic acid was 91.41 mol % at 140 °C with the reaction time of 240 min. Keywords: Levulinic acid, wastewater, renewable, energ

System Efficiency Analysis of SOFC Coupling with Air, Mixed Air-Steam and Steam Gasification Fueled by Thailand Rice Husk

In this work, integrative biomass gasification with solid oxide fuel cell (SOFC) system using rice husk as feedstock was studied under various operations. It was found that the stand-alone mixed air-steam gasification provided significant higher benefit than alone air and steam gasification. The mathematical model was developed to predict the electrical, thermal and overall efficiency of the system. It was found that the SOFC with steam gasification also provided the greatest overall efficiency of 96%. Hence, the steam gasification is a promising option for coupling with SOFC to generate electricity from biomass

Synthesis of Au/C Catalysts by Ultrasonic-Assisted Technique for Vinyl Chloride Monomer Production

In the present work, the ultrasonic-assisted technique is applied to synthesize Au/C catalysts for vinyl chloride monomer (VCM) production via acetylene hydrochlorination. The catalytic performance of the obtained catalysts is compared with that of the catalyst prepared by a conventional incipient wetness impregnation technique. It was found that all the prepared catalysts show high VCM selectivity (> 99.5%). The use of the ultrasonic-assisted technique can significantly improve the catalytic activity and stability of the synthesized Au/C catalysts. An ultrasonic driven time of 6 hours is found to be a promising catalyst for commercial application regarding the catalyst stability. In addition, the effect of operating parameters is investigated. Suitable operating temperature and HCl/C2H2 feed ratio are 180oC and 1.1, respectively

Synthesis and Testing of Zeolite from Industrial-Waste Coal Fly Ash as Sorbent For Water Adsorption from Ethanol Solution

In the present work, zeolite was prepared from industrial-waste coal fired ash (CFA) by fusion technique with and without acid-washing pretreatment under various conditions. The synthesized materials were then tested for water adsorption from bioethanol solution with an aim to produce a high purity ethanol (> 99.5%) for later utilization in gasohol production manufacturing. From our studies, it was found that the impurities (i.e., Fe2O3, TiO2, MgO, CaO, K2O and SO3) in CFA could be efficiently removed by acid-washing pretreatment. Among three different acids studied (i.e. HCl, HNO3, and H2SO4), HCl exhibited the highest pretreatment performance, while the most suitable pretreatment conditions to enhance high purity raw material (up to 85% purity) were by using 20% HCl with the acid to CFA ratio of 25 mlHCl/gCFA at 80°C for 3 h. After fusion at 550ºC with NaOH/CFA mass ratio of 2.25 and further crystallization at 90ºC for 4 h, the pretreated CFA was converted to zeolite; from which the main phases were sodium aluminum silicate hydrate (1.08Na2O•Al2O3•1.68SiO2•1.8H2O) and faujasite-Na (Na2Al2Si2.4O8.8•6.7H2O). Regarding water adsorption testing, the synthesized zeolite provided comparable adsorption performance with the commercial grade molecular sieve. Under three adsorption cycles testing at 85ºC, high ethanol purity (99.8%) could be achieved without deactivation being observed

Reviews on Solid Oxide Fuel Cell Technology

oai:www.engj.org:article/25Solid Oxide Fuel Cell (SOFC) is one type of high temperature fuel cell that appears to be one of the most promising technology to provide the efficient and clean energy production for wide range of applications (from small units to large scale power plants). This paper reviews the current status and related researches on SOFC technologies. In details, the research trend for the development of SOFC components(i.e. anode, electrolyte, cathode, and interconnect) are presented. Later, the current important designs of SOFC (i.e. Seal-less Tubular Design, Segmented Cell in Series Design, Monolithic Design and Flat Plate Design) are exampled. In addition, the possible operations of SOFC (i.e. external reforming, indirect internal reforming, and direct internal reforming) are discussed. Lastly, the research studies on applications of SOFCs with co-generation (i.e. SOFC with Combined Heat and Power (SOFC-CHP), SOFC with Gas Turbine (SOFC-GT)) and SOFC with chemical production) are given

Hydrogen Production From Palmitic Acid Through Autothermal Reforming: Thermodynamic Analysis

This work studies thermodynamic analysis of hydrogen production via autothermal reforming of palmitic acid. A Gibbs free energy minimization method was applied to analyze thermodynamic of syngas production via oxidative reforming of palmitic acid. Equilibrium compositions were estimated at temperature of 800°C, 900°C and 1000°C under atmospheric pressure. Optimal operating temperature and molar feed ratios of; steam to palmitic acid (S/C) and oxygen to palmitic acid (O/C) ranging from 0.5 to 4; were determined. The PTC Mathcad Prime 2.0 is used to calculate enthalpy, entropy and Gibbs free energy. Aspen Plus program was applied for calculation of product yields and heat duty. Maximum yield of 17.88 mole/molePalmitic with S/C of 4 and O/C of 0.5 can be achieved at 1000°C and yield were 7.75 mole/molePalmitic with S/C of 4 and O/C of 4. Production of hydrogen and carbon monoxide increased with increasing temperatures