Catalytic pyrolysis of agricultural residues for bio-oil production

Agricultural residues from Thailand, namely stalk and rhizome of cassava plants, were employed as raw materials for bio-oil production via fast pyrolysis technology. There were two main objectives of this project. The first one was to determine the optimum pyrolysis temperature for maximising the organics yield and to investigate the properties of the bio-oils produced. To achieve this objective, pyrolysis experiments were conducted using a bench-scale (150 g/h) reactor system, followed by bio-oil analysis. It was found that the reactor bed temperature that could give the highest organics yield for both materials was 490±15ºC. At all temperatures studied, the rhizome gave about 2-4% higher organics yields than the stalk. The bio-oil derived from the rhizome had lower oxygen content, higher calorific value and better stability, thus indicating better quality than that produced from the stalk. The second objective was to improve the bio-oil properties in terms of heating value, viscosity and storage stability by the incorporation of catalyst into the pyrolysis process. Catalytic pyrolysis was initially performed in a micro-scale reactor to screen a large number of catalysts. Subsequently, seven catalysts were selected for experiments with larger-scale (150 g/h) pyrolysis unit. The catalysts were zeolite and related materials (ZSM-5, Al-MCM-41 and Al-MSU-F), commercial catalysts (Criterion-534 and MI-575), copper chromite and ash. Additionally, the combination of two catalysts in series was investigated. These were Criterion-534/ZSM-5 and Al-MSU-F/ZSM-5. The results showed that all catalysts could improve the bio-oils properties as they enhanced cracking and deoxygenation reactions and in some cases such as ZSM-5, Criterion-534 and Criterion-534/ZSM-5, valuable chemicals like hydrocarbons and light phenols were produced. The highest concentration of these compounds was obtained with Criterion-534/ZSM-5

เทคนิคการสกัดน้ำมันและการผลิตไบโอดีเซลจากน้ำมันเมล็ดกระบก

วารสารวิชาการและวิจัย มทร.พระนคร, 13(1) : 149-157This paper presents the experimental results of the oil extraction process from wild almond seeds by mechanical and chemical methods. The optimum conditions for the biodiesel production from the extracted oil via transesterification reaction using methanol and potassium hydroxide (KOH) are reported. Chemical extraction was found to be an effective technique for wild almond oil extraction. Simple distillation was used as oil extraction unit applying 140 ml of n-hexane as solvent at 70ºC for 20 min. The oil yield was 43.11±0.98%. This extracted oil was used as raw material for biodiesel production with the maximum yield of 83.20±1.11%. The optimum conditions for biodiesel production were the catalyst loading of 0.5 wt% and 9:1 molar ratio of methanol to oil in a controlled reaction temperature of 70ºC for 60 min. Finally, the properties of biodiesel were analyzed and most properties met the requirements of the department of energy business standard.Rajamangala University of Technology Phra Nakho

Application of solid media for enhancing the temperature distribution within a downdraft kiln during clay brick firing

Industrial production of fired clay bricks typically experiences problems related to the brick quality such as insufficient-firing, over-burning, and distortion due to twisting, bulging, warping or cracking, which affect their color and strength. These issues are derived mainly from the poor temperature control and heat distribution. To mitigate this problem, a simple technique is proposed in this work by inserting solid media between bricks during the firing process. Three types of solid media including alumina balls, clay balls and sandstone sheets were tested. The use of the solid media was found to significantly (93%) improve the temperature distribution in the kiln. The temperature difference between the bottom and top bricks reduced from 344°C (without the solid media) to a minimum of 23°C when alumina balls were applied with the sandstone sheets. The properties of the bricks in terms of water absorption and shrinkage were found to be 11.3-11.9% and 1.3-1.6%, respectively, which are comparable with those of the commercial bricks. Interestingly, the compressive strength of the bricks produced with the aid of the solid media was enhanced significantly, especially when the sandstone sheets were used together with the alumina balls as the compressive strength was double that of the industrial bricks

Hydrodeoxygenation of Oxygenates Derived from Biomass Pyrolysis Using Titanium Dioxide-Supported Cobalt Catalysts

Bio-oil upgrading to produce biofuels and chemicals has become an attractive topic over the past decade. However, the design of cost- and performance-effective catalysts for commercial-scale production remains a challenge. Herein, commercial titania (TiO2) was used as the support of cobalt (Co)-based catalysts (Co/TiO2) due to its low cost, high availability, and practicability for commercialization in the future. The Co/TiO2 catalysts were made with two different forms of TiO2 (anatase [TiO2–A] and rutile [TiO2–R]) and comparatively evaluated in the hydrodeoxygenation (HDO) of 4-propylguaicol (4PG), a lignin-derived model compound. Both Co/TiO2 catalysts promoted the HDO of 4PG following a similar pathway, but the Co/TiO2–R catalyst exhibited a higher activity in the early stages of the reaction due to the formation of abundant Ti3+ species, as detected by X-ray photoelectron spectroscopy (XPS) and hydrogen–temperature programed reduction (H2–TPR) analyses. On the other hand, the Co/TiO2–A catalyst possessed a higher acidity that enhanced propylcyclohexane production at prolonged reaction times. In terms of reusability, the Co/TiO2–A catalyst showed a higher stability (less Co leaching) and reusability compared to Co/TiO2–R, as confirmed by transmission electron microscopy (TEM) and inductively coupled plasma optical emission spectroscopy (ICP-OES) analyses. The HDO of the real bio-oil derived from pyrolysis of Leucaena leucocephala revealed that the Co/TiO2–A catalyst could convert high oxygenated aromatics (methoxyphenols, dimethoxyphenols, and benzenediols) to phenols and enhanced the phenols content, hinting at its potential to produce green chemicals from bio-feedstock

The characteristics and emissions of low-pressure densified torrefied elephant dung fuel briquette

Elephant dung is the camp's undigested fiber waste. For more effective waste management, the conversion of dung to torrefied solid and the formation of solid torrefied into fuel briquettes, as well as their properties, were investigated. The dung was improved through torrefaction at 280ºC for 150 sec in a pilot-scale reactor with a feeding rate of 600 g/h. The torrefied elephant dung had 17 MJ/kg of HHV, a solid yield of 79%, and a fixed carbon content of 20%. A mixture of torrefied dung, binder, and water was compressed at 40 bars to a density of 860 kg/m3, or 12 GJ/m3. Their H/C and O/C atomic ratios were in the range of typical biomass. However, due to their moisture content of over 7%, the HHV of the fuel briquettes was below 17 MJ/kg. Moreover, their thermal efficiency was less than 7% due to durability issues, despite having a great fuel ratio and thermal stability. The combustion of these briquettes resulted in less than 850 ppm of CO. To improve the combustibility of this solid biofuel, it is recommended to develop a production process and a suitable stove specifically for these briquettes