Fast Pyrolysis Of Rice Husk Research Articles

Parametric study of the catalytic fast pyrolysis of rice husk over hierarchical micro-mesoporous composite catalyst in a microwave-heated fluidized bed

To improve the efficiency of the catalyst fast pyrolysis (CFP) of rice husk and the quality of bio-oil, we integrate both microwave heating and fluidized bed reactor methods and build a microwave-heated fluidized bed system. In this study, the liquid yield from the CFP of rice husk in a microwave-heated fluidized bed (55.3 wt.%) is significantly higher than that obtained from a fixed bed (47.6 wt.%). Meanwhile, the relative content of hydrocarbons from microwave assisted catalytic fast pyrolysis (MACFP) of rice husk (RH) over a hierarchical micro-mesoporous composite molecular sieve (HM-2.0 T) is 67.6 % higher than that (51.6 %) of the organic base modified HZSM-5 (HT-2.0) and HZSM-5 (40.2 %) in the microwave-heated fluidized bed system. Furthermore, we focused on the ratio of biomass to catalyst in CFP processing and discover that the increased amount of catalyst promoted the decarbonylation and decarboxylation reactions, producing more hydrocarbon compounds, however, the excessive amount of catalyst does not contribution to higher monocyclic aromatic hydrocarbon selectivity. Besides, the hierarchical micro-mesoporous composite catalyst had strong regeneration ability and reusability. The selectivity of monocyclic aromatics remained high when the regeneration times increase from 1 to 4, which provided possibilities for applications of hierarchical micro-mesoporous composite catalyst in industrial production in the future.

Fast pyrolysis of rice husk under vacuum conditions to produce levoglucosan

Levoglucosan (LG)-enriched pyrolytic oils were obtained from rice husk by lab-scale fast pyrolysis under vacuum conditions. We studied the effect of the pyrolysis temperature (300−700 °C) and the pretreatment of the biomass, on the pyrolysis product yields and the selectivity for LG formation. The maximum oil yield (47 wt.%) was obtained from hydrochloric acid-leached rice husk at 400 °C, producing 1.4 times more than the amount of oil produced from untreated rice husk at the same temperature. Anhydrosugars were the predominant compounds found in bio-oils under all conditions assessed, LG being the main product. Depending on the pyrolysis conditions, LG concentration was between 9−30 wt.% considering the bio-oil mass, and between 4−60 wt.% considering the initial cellulose mass. 1H NMR experiments were carried out as an alternative and simple technique to directly determine the amount of LG in bio-oils.

Study of rice husk continuous torrefaction as a pretreatment for fast pyrolysis

Rice husk (RH) is one of the most available biomasses in southern Brazil. One possible solution is to carry out the fast pyrolysis of RH. To improve the quality of liquid products biomass can be torrefied before being pyrolyzed. The influence of torrefaction on the physical and chemical properties of pyrolysis products was explored. Both torrefaction and pyrolysis reactions were performed in a fluidized bed reactor in a continuous mode. Sample with torrefaction and pyrolysis at 500 °C presented the highest biochar yield (44.2 wt.%). The torrefaction step produced a lower yield of bio-oil. In contrast, the highest bio-oil yield (43.6 wt.%) was achieved in the sample without torrefaction at 500 °C. The increase in temperature to 750 °C provided a specific area of 16.7 m²/kg for biochar. The highest value of HHV for bio-oil, 28 MJ/kg, was obtained via direct pyrolysis at 750 °C, which also led to the lowest water content of 5.9 wt%. According to the NMR analysis, the torrefaction liquid (TL) presented a high quantity of water and alcohols in its composition (92.5 %).

Kinetic study of carbonaceous deposit formation and catalyst deactivation in hydrotreating of fast pyrolysis bio-oil

Fast pyrolysis of biomass followed by hydrotreating of bio-oil is considered to be a promising thermochemical conversion process of biomass to liquid fuel. Catalytic hydrotreating converts the crude bio-oil from biomass pyrolysis into liquid intermediates with reduced oxygen content, and low viscosity and acidity. However, effective lifetime of catalyst can be significantly reduced by coking which has been recognized as the main cause of catalyst deactivation during the hydrotreating process. In this study, similar phenomenon has been observed but the catalyst deposit was different from the reported coke and thus a new term of carbonaceous deposit is introduced. Kinetics of the carbonaceous deposit formation and its characteristics have been investigated for hydrotreating of bio-oil derived from fast pyrolysis of rice husk using commercial HTB-45 Ni-based catalyst. A mathematical model for the hydrotreating process, which is based on key chemical reactions and consists of ordinary differential equations (ODEs), has been developed and solved with the kinetic parameters being obtained from the experiments. Results of this study are helpful for better understanding and optimization of the catalytic upgrading of fast pyrolysis bio-oil.

Microwave-assisted catalytic fast pyrolysis of rice husk over a hierarchical HZSM-5/MCM-41 catalyst prepared by organic base alkaline solutions

This paper reports the results obtained for microwave-assisted catalytic fast pyrolysis (MACFP) of rice husk. The MACFP process employed a hierarchical catalyst prepared via a combination of organic alkali treatment (TPAOH) and the generation of an external layer of MCM-41-type mesoporous channels. We propose this catalyst which is used for the first time for pyrolysis of lignocellulosic biomass, as a tool to reduce coke agglomeration and increase hydrocarbon yields. Our results indicate that during catalyst preparation the mass fraction of cetyltrimethylammonium bromide (CTAB) has a direct effect on the content of MCM-41 formed on top of the HZSM-5 core. For MACFP, we hypothesize that the small molecules generated from thermal decomposition of rice husk react further to form aromatic and aliphatic hydrocarbons by decarbonylation, decarboxylation, oligomerization and aromatization. The highest hydrocarbon yield (60.5%) was obtained for a catalyst modified by a 2.0 mol/L TPAOH solution, with 10 wt% of CTAB (template for producing MCM-41), as well as with digestion and crystallization at 110 °C for 24 h. In addition, the highest liquid yield (47.6 wt%) was obtained at 550 °C. The relative content of hydrocarbons goes through a maximum of 60.5% with CTAB mass fraction which was higher than values obtained with MCM-41 (3.2%) and HZSM-5 (36.0%). Characterization and catalytic testing results suggest that the digestion temperature plays a more important role in the catalyst synthesis than the crystallization temperature. High digestion temperature (120 °C) decreases the overall hydrocarbon selectivity from 60.5% (110 °C) to 39.2%. The relative content of oxygenates reached the lowest value of 35.9% at the digestion and crystallization temperature of 110 °C. The synergistic effect of the MCM-41 shell and the HZSM-5 core promotes the catalytic activity, leading to outstanding deoxygenation capabilities and excellent selectivity to BTEX (52.7%).

Continuous fast pyrolysis of rice husk in a fluidized bed reactor with high feed rates

Rice husks were processed in a laboratory-scale fluidized bed reactor with a SiC bed. With the objective of smaller reactor volumes and lower operational costs in scale-up, elevated feed rates of ca. 875 g/h were explored, equivalent to feed rate per area of 35 kg/m2 min and carrier gas to biomass ratios of 0.8 wt/wt. Temperatures of 450, 525, and 600 °C, and SiC bed heights of 4.9 and 6.5 cm were tested. Experiments with a sand bed, a poorer heat conductor than SiC, were conducted as well. In these high feed rate conditions, a maximum organic phase yield of 31 wt% was obtained at the highest temperature of 600 °C and 6.5 cm of bed, 20% volatile content remained in the product char. Experiments with sand bed elucidated that the heat transfer bottleneck is the conduction step inside biomass particles. Higher inert bed heights are suggested to increase biomass particle residence time in the dense sand bed, achieving better devolatilization and lower temperatures. Finally, a scale-up analysis with extrapolated lab-scale results shows that operating with a high feed-rate per area, as demonstrated, could lead to reactor volumes six times smaller than other reported points, being more suitable for mobile units.

Process design and evaluations for producing pyrolytic jet fuel

AbstractIn this study, process simulation and techno‐economic analysis (TEA) were conducted to evaluate the production of renewable jet fuel (RJF) through the pyrolysis‐to‐RJF process. The process model was developed based on experimental results for the renewable jet fuel production process using the fast pyrolysis of rice husk, hydro‐processing of pyrolytic oil, and hydro‐cracking / isomerization of hydro‐processed oil. The mass and energy flows were input into the TEA model, which was established based on local conditions in Taiwan. The study included three parts: (1) the mass, energy and carbon balances – the major product, RJF, gave an energy yield of 26.8%, a mass yield of 9%, and a carbon yield of 21%; (2) an economic analysis – the MJSP of RJF for the pyrolysis‐to‐RJF process was $3.21/L, based on the plant capacity of 600 tonnes per day; (3) a sensitivity analysis: the impacts of the feedstock cost, catalyst life, co‐product selling price, catalyst cost, hydrogen cost, and plant capacity were discussed. This study demonstrated the economic potential of locally developing a pyrolysis‐to‐RJF process to produce RJF from solid biomass. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd

Catalytic fast co-pyrolysis of waste greenhouse plastic films and rice husk using hierarchical micro-mesoporous composite molecular sieve

Catalytic fast co-pyrolysis of waste greenhouse plastic films and rice husk over a hierarchical HZSM-5/MCM-41 catalyst was performed in an analytical Py-GC/MS. We evaluated the effect of pyrolysis temperature and the ratio of rice husk to waste greenhouse plastic films on the total peak area of condensable organic products and CO2. In order to evaluate synergy possibilities among the two feedstocks, we performed non-catalytic pyrolysis and catalytic fast pyrolysis of rice husk and waste greenhouse plastic films separately. In addition, we report results for the catalytic fast co-pyrolysis of the mixture rice husk and waste greenhouse plastic films. The maximum relative content of hydrocarbons from catalytic fast co-pyrolysis of rice husk and waste greenhouse plastic films is obtained at 600 °C. When the mass ratio of rice husk to waste greenhouse plastic films is 1:1.5, the relative content of hydrocarbons reaches a maximum (71.1%). The hierarchical micro-mesoporous composite molecular sieve used in this work has outstanding catalytic activity and increases the relative content of hydrocarbons.

Catalytic pyrolysis of biomass with potassium compounds for Co-production of high-quality biofuels and porous carbons

This paper studied the catalytic pyrolysis of rice husk (RH) with different K-compounds (i.e., KOH, K2CO3, and K2C2O4) for co-production of biofuels and porous carbons. The decomposition of biomass occurred at lower temperature ranges due to the catalytic performance of K-compounds, following the order of KOH > K2CO3 > K2C2O4. By fast pyrolysis of RH with the K-compounds, the number of organic compounds was significantly reduced. More hydrocarbons (e.g., benzene, long-chain alkanes) were generated due to the in-situ catalytic upgrading (e.g., deoxygenation) of bio-oil. Pyrolysis of biomass with K-compounds could also accelerate the generation of unsaturated aliphatic hydrocarbons. In particular, pyrolysis of RH with K2C2O4 could result in the bio-oil with high-content of hydrocarbons and with low-content of oxygenated compounds (e.g., acids, phenols). Furthermore, the activated char with hierarchically micro-mesoporous structure was applied for toluene sorption. The pristine biochar had a relatively low adsorption time and capacity. By the chemical activation followed by the washing process, the specific surface area (SBET) of the RH-derived chars was significantly increased. The RHC-K2C2O4 had a maximum SBET of 1347 m2/g due to its mild activation process, which further contributed to a highest breakthrough time (1230 min) and capacity (609.38 mg/g) on toluene adsorption.

Uncertainty estimation approach in catalytic fast pyrolysis of rice husk: Thermal degradation, kinetic and thermodynamic parameters study

The aim of this study was to understand the influence of catalyst in thermal degradation behavior of rice husk (RH) in catalytic fast pyrolysis (CFP) process. An iso-conversional Kissinger kinetic model was introduced into this study to understand the activation energy (EA), pre-exponential value (A), Enthalpy (ΔH), Entropy (ΔS) and Gibb’s energy (ΔG) of non-catalytic fast pyrolysis (NCFP) and CFP of RH. The study revealed that the addition of natural zeolite catalyst enhanced the rate of devolatilization and decomposition of RH associated with lowest EA value (153.10 kJ/mol) compared to other NCFP and CFP using nickel catalyst. Lastly, an uncertainty estimation was applied on the best fit non-linear regression model (MNLR) to identify the explanatory variables. The finding showed that it had the highest probability to obtain 73.8–74.0% mass loss in CFP of rice husk using natural zeolite catalyst.

The effect of acid washing pretreatment on bio-oil production in fast pyrolysis of rice husk

Rice husk is a kind of biomass feedstock with high ash content. The effect of acid washing (HCl, HF and H3PO4) on the inorganic contents in rice husk was analyzed in this study. The optimal pretreatment conditions for pyrolysis product distribution, including acid concentration, washing temperature and washing time, were investigated via pyrolysis–gas chromatography/mass spectrometry (Py–GC/MS). Compared with HF and H3PO4, HCl showed the best removal efficiency of alkali and alkaline earth metals (AAEMs) with removal efficiency up to 98% for K, 93% for Ca, 100% for Na and 91% for Mg. Acid washing could increase the yield of specific products, especially sugars. Considering economic costs and the wide range of applications, HCl is the most suitable acid for washing. In order to get the highest yield of all kinds of products, the optimal pretreatment condition of HCl washing is the concentration for 2 mol/L, washing temperature for 60 °C and washing time for 1 h.

Catalytic Upgrading of Bio-oil Produced from Pyrolysis of Rice Husk

Rice husk is one of the most widely available agriculture residues. It was a promising eco-friendly alternative source of renewable energy in the context of current energy scenarios. Fast pyrolysis technologies can transform rice husk into bio-oil considering its physical and chemical properties. Catalytic pyrolysis experiments have been carried out on Japanese rice husk to obtain bio-oil using a fixed-bed pyrolysis reactor with the use of the catalyst and comparison was done to analyze the changes in the bio-oil properties and yield. The fast pyrolysis of rice husk has been performed in the temperature range of 400-600 °C using the experimental pyrolysis reactor. The objective of this research is to explore the possibility to upgrade bio-oil produced from rice husk. The catalytic cracking is the most promising bio-oil upgrading processes, and it can remove oxygenated compounds from bio-oil via H2O, CO and CO2. The result showed that by using two heating units, even without catalyst, the upgrading was achieved well. In this research, two heating units were employed so that the raw bio-oil will separate in the first heating unit and the cracking in the second heating unit. The raw rice husk bio-oil produced and the upgraded bio-oil were characterized by measuring their element content, water content and the chemical composition of its organic fraction. The catalysts used were HZSM-5 zeolite and other non-commercial catalyst like rice husk ash which were appropriately effective in the bio-oil crack upgrading to reduce cost.

Hydrogen production via steam reforming of acetic acid over biochar-supported nickel catalysts

Development of high-performance and low-cost catalysts will make the biomass-derived hydrogen production technology, steam reforming of bio-oil, becomes to be more and more economical and promising. Biochar, which was produced via fast pyrolysis of rice husk, was activated by different methods, and then it was used as a support for the nickel catalyst, and tested in the steam reforming of acetic acid. The physicochemical properties of the Ni/biochar (BCx) catalysts were characterized by BET, XRD, SEM, TEM and H2-TPR. The development of pore structure and improvement of surface properties were achieved by the activation. Subsequently, the activity of several catalysts on hydrogen production was investigated. It was found that the Ni/BC4 catalyst (biochar activated by KOH alkalization coupled with HNO3 reflux) exhibited the best catalytic performance. Under the conditions of T = 700 °C, S/C = 2.5 and LHSV = 10 h−1, the carbon conversion and hydrogen yield reached to 91.2% and 71.2%, respectively.

Catalytic fast pyrolysis of rice husk for bio-oil production

A lab-scale catalytic pyrolysis unit with the feeding rate of 100–500 g h−1 was designed and manufactured with a fluidized bed reactor. The effects of reaction temperature, catalyst weight and catalyst position on the properties of pyrolysis products were investigated. Subsequently, the mechanism of biomass pyrolysis was studied through Py-GC/MS analysis. The optimal pyrolysis temperature for a higher yield and quality of bio-oil was 500 °C. The highest bio-oil yield was 46.9 wt% with biochar, and non-condensable gas yields of 30.0 wt% and 23.1 wt%, respectively at 500 °C. The minimum value of the water content of bio-oil samples was 13.39 ± 0.22% under 500 °C. The catalyst can significantly increase the water content of bio-oil and reduce the ash content, HHV, solid content and viscosity of bio-oil. In the process of biomass fast pyrolysis, the cellulose, hemicellulose and lignin were pyrolyzed to monomers. Then some chemicals were produced from these monomers through a series of reactions: isomerization reaction, dehydration reaction, retro-aldol reaction, esterification, carbonyl reaction and so on. In catalytic pyrolysis, the active site of catalyst acts as deoxidizer. Hydrocarbon radicals' pool was formed through monomers thermal cracking. Then some relatively stable chemicals were formed through reactions among those radicals.

Catalytic fast pyrolysis of rice husk: Effect of coupling leaching with torrefaction pretreatment

The effect of coupling leaching with torrefaction pretreatment process on bio-oil production from catalytic fast pyrolysis using ZSM-5 zeolite catalyst was evaluated by Py-GC/MS. During coupling leaching with torrefaction pretreatment, the fuel characteristics and structural characteristics of rice husk samples were changed, which were evaluated using proximate, ultimate, and calorific analyses, Fourier transform infrared spectroscopy (FTIR) and X-ray diffractometer (XRD) techniques. The experimental results of catalytic fast pyrolysis indicated that coupling leaching with torrefaction pretreatment further improved the relative contents of BTX (benzene, toluene and xylene) compounds in bio-oil compared to that of raw rice husk sample. It was mainly ascribed to the effective removal of metallic species during leaching process. In addition, the selective removal of hemicellulose fraction and the increasing lignin fraction and changes in the structure of lignin (cleavage of ether linkages and demethoxylation) during torrefaction process also plays positive roles. Severe torrefaction process resulted in the cross-linking and charring of sample, thus reducing the formation of BTX compounds. Thus, coupling leaching with middle torrefaction pretreatment process was the optimum pretreatment conditions for catalytic fast pyrolysis of rice husk samples.

Effects of heating rate on the evolution of bio-oil during its pyrolysis

Bio-oil from the fast pyrolysis of biomass can be converted to solid carbon materials, chemicals and syngas by various thermochemical conversion methods. As a first step in all of these processes, bio-oil undergoes drastic components changes due to its exposure to the elevated temperature. Understanding the effects of heating rate on bio-oil transformation during its pyrolysis is therefore crucial for effective utilization of bio-oil. In this study, a bio-oil sample produced from the fast pyrolysis of rice husk at 500 °C was pyrolyzed in a fixed-bed reactor at temperatures between 300 and 800 °C at three different heating rates: fast (≈200 °C/s), medium (≈20 °C/s), and slow (≈0.33 °C/s). In addition to the quantification of coke and tar yields, the tar was characterized with an ultraviolet (UV) fluorescence spectroscopy, a gas chromatography/mass spectrometer (GC/MS) and a Fourier transform ion cyclotron resonance mass spectrometer (FT-ICR MS). Our results indicate that slow heating rates promote polymerization of bio-oil components, particularly at low temperatures (<500 °C), resulting in higher primary coke yields than that of the fast heating rates. Decomposition reaction was found to be pronounced at fast heating rates, causing decreases in the tar yields and abundance of light compounds. The increases in the yields of the secondary coke, the formations of more condensed aromatic structures and macromolecules (m/z > 500) were also promoted at fast heating rates via the more intense secondary reactions.

INFLUENCE OF FAST PYROLYSIS WITH TEMPERATURE ON GAS, CHAR AND BIO-OIL PRODUCTION

Rice husk is among the products that stand out in use, and it is used as an alternative source of energy. The use of rice husk as biomass in the feeding of pyrolytic reactors for power generation and chemical products can reduce the environmental problem destination of this waste. The advantages of this process are in the proper disposal of this waste and energy generation. Fast pyrolysis of the rice husk was carried out in temperatures of 400-600°C. This work aims to evaluate the influence of temperature on yield and product composition of the gas, bio-oil, and char. The yield of bio-oil proved to be efficient (62 wt.% at 450°C) due to the high heat transfer and mass, as well as the residence time in the reactor. In addition, bio-oil production decreases slightly due to increased gas yield (1 to 15 wt.%) as the temperature increases in the range of 400-600°C, with the composition being severely affected, i.e., The concentration of CO increases and that of CO2 decreases. In addition, a slight increase in the concentration of CH4 and C2-C4 hydrocarbons occurs with increasing temperature. The yield of char at 400°C and 600°C was 41.14-34.77 wt.%, respectively, corresponding to a decrease of 16 wt.%. The char obtained is of low heating value but has good features for the production of active carbons and amorphous silica. These results demonstrate the efficiency and optimization of the fast pyrolysis of rice husk, in order to obtain biooil and char.

Bio-oil production from fast pyrolysis of rice husk in a commercial-scale plant with a downdraft circulating fluidized bed reactor

Bio-oil, a promising candidate to replace fossil fuels, has received considerable attention for its sustainability, resource diversity and environmental benefits. Industrial production of bio-oil is urgently needed. In this study, a downdraft circulating fluidized bed reactor commercial-scale fast pyrolysis plant with biomass throughput of 1–3th−1 is studied. Rice husk was processed at a fast pyrolysis temperature of 550°C to evaluate the plant operation status. The system was continuously operated for 80.42h. The thermal properties of the feedstock (rice husk), dust (separated from feedstock), char and heat carrier were analyzed and the bio-oil properties such as water content, pyrolytic water content, viscosity, density, pH, heating value, solid content and ash content were analyzed and presented. All the tested properties of the bio-oil meets the pyrolysis liquid biofuels standards in ASTM D7544-12 for Grade G biofuels, except for the water content of the bio-oil, which is slightly higher than that of Grade G biofuels. In energy balance analysis, the potential recovered energy of the three main products was 8.0±1.1, 2.1±0.1 and 5.3±0.7MJkg−1 for bio-oil, char and non-condensable gas, respectively, which shows that the largest portion of the energy in biomass was recovered in the bio-oil.

Catalytic fast pyrolysis of rice husk: Influence of commercial and synthesized microporous zeolites on deoxygenation of biomass pyrolysis vapors

Research on utilization of abundant rice residue for valuable bioenergy products is still not explored completely. A simple, robust, cheap, and one-step fast pyrolysis reactor is still a key demand for production of bioenergy products, ie, high quality bio-oil and biochar. Bio-oil extracted from fast pyrolysis does not have adequate quality (eg, acidic and highly oxygenated). Catalytic fast pyrolysis using zeolites in the fast pyrolysis process effectively reduces the oxygen content (no H2 required). In this paper, the zeolites with different pore sizes and shapes (small pore, SAPO-34 (0.56) and ferrierite (30); medium pore, ZSM-5 (30), MCM-22 (30), and ITQ-2 (30); and large pore zeolite, mordenite (30)) were tested in a drop-type fixed-bed pyrolyzer. Catalytic deoxygenation is conducted at 450°C at the catalyst/biomass ratio of 0.1. Zeolite catalysts, its pore size and shape, could influence largely on deoxygenation. It was found that the small pore zeolites did not produce aromatics as compared to higher amount of aromatics formed in case of medium pore zeolites. ZSM-5 and ITQ-2 zeolites were especially efficient for the higher deoxygenation of biomass pyrolysis vapors due to better pore dimension and higher acidity.

Application of the SARA method for determination of hydrocarbons by GC/qMS in bio-oil obtained by fast pyrolysis of rice husk

This study presents the results of the use of fractionation preparative liquid chromatography (PLC) on columns of silica (based on the SARA method, traditionally used for oil samples).For characterization of bio-oils obtained by fast pyrolysis of rice husk. The method distributes compounds separating into four fractions, the majority polar compounds (F3 and F4) and hydrocarbons (F1 and F2). The fractions were analyzed by GC/MS allowing the identification and semi-quantitative determination of aliphatic hydrocarbons and HPAS. After the fractionation by PLC, only F1, F2 and F3 were possible to identify, a total of 180 compounds. The fractionation based on the SARA method, with modification, produced fractions (F1 and F2) free of polar compounds permitting the identification of aliphatic hydrocarbons and PAHs.