Catalytic Pyrolysis Of Rice Husk Research Articles

Catalytic pyrolysis of rice husk to co-produce hydrogen-rich syngas, phenol-rich bio-oil and nanostructured porous carbon

How to achieve high value modification of biomass through simple process and low cost is an important bottleneck in the development of biomass energy. In this study, hydrogen-rich syngas, phenol-rich bio-oil and high specific surface area nanostructured porous carbon materials were synthesized by one-step in situ catalytic pyrolysis at 500 °C. Composition and physicochemical property tests of the three-phase products showed that KOH promotes ring opening and bond breaking of macromolecules in the bio-oil, improves the directional selectivity of phenolic compounds, and generates more small molecule gases. Molten K+ and water vapor etched the biomass to prepare porous carbon with high graphitization and rich pore structure and generate more H2. Further electrochemical characterization showed that the porous carbon material had good specific capacitance and cyclic stability. This study provides a new idea for the utilization of pyrolysis polygeneration technology of agroforestry biomass resources, and it is also of guiding significance for the research of high-value utilization of biomass resources.

Catalytic pyrolysis of rice husk to selectively produce furfural over zeolite beta with post aluminum impregnation

AbstractIn the present work, three zeolite‐beta based catalysts with post impregnation of aluminum are evaluated for conversion of rice husk to furfural at atmospheric pressure in the presence of sodium chloride as promoter. The synthesized catalysts were characterized by nitrogen adsorption–desorption isotherm, scanning electron microscopy, X‐ray diffraction, and pyridine Fourier transform infrared spectroscopy. The activity of in house synthesized/modified catalysts is studied at preliminary optimized reaction conditions of 375°C and 47 min with variation in feed/catalyst/promoter ratio. Purity and yield of furfural was obtained by gas chromatography analysis with flame ionization detector in a batch reactor. Results shows that zeolite beta with 5 wt % post aluminum impregnation gave highest yield of bio‐oil (60.3 wt%) with 88% selectivity toward furfural in the presence of sodium chloride (5 wt% of feed) and sulfuric acid (10 wt% of feed).

Catalytic pyrolysis of rice husk over defect-rich beta zeolites for biofuel production

The Coats-Redfern method was used to identify the catalytic and non-catalytic pyrolysis of rice husk biomass kinetics by using thermogravimetric analysis. MTES-beta-zeolite and beta-zeolite were synthesized by dry gel conversion method. Both synthesized zeolites and commercial beta-zeolite were mixed with ground rice husk in a 1:0.03 ratio by mass. Thermal degradation for catalytic and non-catalytic pyrolysis of rice husk biomass occurred at 523 K to 823 K. Conversions were majorly observed in Section I (523–633 K) and Section II (723–823 K) temperature ranges. Order and diffusion-based models were in approximation with each other for both temperature ranges. From the Ea trends, it can be understood that MTES beta-zeolite has no significant effect on pyrolysis in Section I and has promising results in Section II. The beta-zeolite and commercial beta-zeolite gave better results for all reaction models in both sections by lowering the activation energies for catalytic pyrolysis of RH compared to those for non-catalytic pyrolysis. By comparing catalytic with non-catalytic pyrolysis of rice husk, activation energy significantly varied for both sections. Thermodynamic parameters (ΔH) and (ΔG) values indicated the activated complex formation and non-spontaneity of the reaction. The negative value of (ΔS) suggested a more ordered state. Furthermore, pyrolysis of rice husk with commercial beta zeolite was performed and biochar produced with a yield of approximately 75%. Different organic compounds were also obtained in the bio-oil which include different aliphatic compounds.

Catalytic pyrolysis of rice husk with SnCl2, Al2O3.4SiO2.H2O, and MoS2 for improving the chemical composition of pyrolysis oil and gas

Pyrolysis of Indian variety rice husk was carried out in a semi-batch reactor in the presence of SnCl2, Al2O3.4SiO2.H2O, and MoS2 catalysts at a fixed temperature (550 °C), heating rate (50 °C min−1), and N2 flow rate (0.3 L min−1). The yield of pyrolysis oil increased in the presence of Al2O3.4SiO2.H2O catalyst but deteriorated in presence of SnCl2, and MoS2 catalyst. At 550 °C, the maximum pyrolysis oil yield from non-catalytic pyrolysis (NCP) was 37.46 wt% and with Al2O3.4SiO2.H2O catalyst it was 38.41 wt%. The yield of H2 (7.27 mol %) in pyrolysis-gas after catalytic pyrolysis (CP) was 0.72 mol% higher than NCP (6.55 mol %). The gross calorific value (GCV) of pyrolysis-gas after CP increased to 5.99 MJ m−3 from 3.84 MJ m−3 (NCP). High lignin contained in rice husk gave a better CH4 yield of 10.13 mol. %. Reduction in water content (3.07–5.77 wt %) of pyrolysis oil after CP elevated the high heating value (HHV) to 28.61 from 22.41 MJ kg−1. A 3.0–4.58 mol. % reductions in the acidic compound content after CP impacted the pH and TAN of pyrolysis oils. The Al2O3.4SiO2.H2O catalyst elevated the area percentage of naphthenic (0.54 mol. %), olefinic (1.98 mol. %), aromatic (4.18 mol. %), and paraffinic (4.42 mol. %) compounds in pyrolysis oil. A 3.86 mol. % increase in the phenolic compounds was observed in presence of MoS2 catalyst. Approximately, 22 wt% loss in oxygen with 21 and 2.65 wt% increases in the carbon and hydrogen content of biochar elevated the HHV to 30.60 MJ kg−1 after CP.

Catalytic pyrolysis of rice husk with nickel oxide nano particles: kinetic studies, pyrolytic products characterization and application in composite plates

Catalytic pyrolysis of rice husk with nickel oxide nano particles: kinetic studies, pyrolytic products characterization and application in composite plates

Catalytic pyrolysis of biomass with char modified by cathode materials of spent lithium-ion batteries for tar reduction and syngas production

The char modified by the battery cathode material was studied for catalytic pyrolysis of rice husk (RH). Compared to the direct mixing, the addition of cathode material to char by the impregnation was more favorable to synthesize the lignin char catalyst (i.e. char 1) with hierarchical pore structure and larger specific surface area. The char 1 decreased the Ea of the RH pyrolysis from 79 kJ/mol to 66 kJ/mol. The char 1 decreased the yield of liquid product from 23.2% to 12.3% and increased the yield of gas product from 35.2% to 52.2%. The char 1 decreased the contents of acids from 20.6% to 3.6% and phenols (tar surrogates) from 29.4% to 8.0%. The increase of hydrocarbons and CO2 indicated that the char catalysts had high catalytic reactivity in converting the oxygenated components (e.g., sugars, furans, acids, phenols) into light hydrocarbons (e.g., alkanes, aromatics) and micro-molecular gases (e.g., CO2, H2).

Novel Ni–Al nanosheet catalyst with homogeneously embedded nickel nanoparticles for hydrogen-rich syngas production from biomass pyrolysis

In this work, an innovative porous Ni–Al nanosheet catalyst synthesized by a homogeneous precipitation method via urea hydrolysis is proposed for enhanced hydrogen-rich syngas production from catalytic pyrolysis of rice husk in a two-stage reactor system. The role of synthesis temperature in modulating the crystalline composition, particle size, metal dispersion as well as porous structure of resulting Ni–Al nanocomposite has been delineated. The results indicate that fine spherical NiO and metallic Ni0 nanoparticles are homogeneously embedded in amorphous Al2O3 matrix for all Ni–Al catalysts, which also have developed bimodal micro/mesoporous structure with high surface areas (513–948 m2/g). Catalytic tests show that these highly active catalysts exhibit almost ten times higher hydrogen production rate (7.74–17.39 mmol/g biomass) and H2/CO molar ratio (1.96–2.74) than that in the absence of catalyst (0.56–1.64 mmol/g, 0.11–0.24) by tuning catalytic temperatures. The Ni–Al catalysts that with the presence of metallic Ni0 and developed porous structure exhibit higher catalytic activity and suppression of coke deposition through providing more active sites for catalytic cracking and reforming reactions, and rapid diffusion of intermediate products.

Simultaneous improvement in qualities of bio-oil and syngas from catalytic pyrolysis of rice husk by demineralization

ABSTRACT This study aims to investigate the influences of different demineralization pretreatment processes on the properties of liquid and gas products from catalytic pyrolysis via activated carbon catalyst. To achieve this goal, deionized water, hydrochloric acid, and acetic acid were used to remove ash. The results indicated that leaching could remove a large amount of alkali and alkaline earth metals (AAEMs). Besides, the experiments of different leaching solutions on catalytic fast pyrolysis of rice husks were conducted. It can be found that compared with direct pyrolysis, the catalytic pyrolysis produced more gas products, in which CO increased by 6.49%, while the bio-oil was concentrated in phenols (more than 90%). After demineralization, the content of CO in gas products further increased by 8.04%, while the relative content of phenol in bio-oil enhanced by 14.79% as well. Catalysis can enrich phenol in bio-oil, and leaching can enhance this enrichment. Meanwhile, demineralization can further improve the quality of syngas. The sample after demineralization by hydrochloric acid performed best on catalytic fast pyrolysis, where CO accounts for 57.68% volume of gaseous product and phenol accounted for 68.21% of bio-oil.

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.

Comparative study of in-situ catalytic pyrolysis of rice husk for syngas production: Kinetics modelling and product gas analysis

Pyrolysis of rice husk (RH) in the presence of three different types of catalysts (nickel, natural zeolite, and coal bottom ash) for syngas production were investigated by TGA-MS. The catalyst to RH ratio of 0.1 was pyrolyzed at different heating rates of 10, 20, 30, and 50 Kmin-1 in the temperature range of 323 K–1173 K. Furthermore, X-ray diffraction (XRD), Brunaur-Emmett-Teller (BET), field emission scanning electron microscope (FESEM) and X-ray fluorescence (XRF) were employed to understand the physiochemical properties and activities of the catalysts before and after pyrolysis of RH. Lastly, four different types of kinetic models such as first-order Coats-Redfern equation, Friedman, Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS) were employed to determine the activation energy (EA). The kinetic analysis revealed that the EA values reduced when catalysts were introduced into RH as compared to absence of catalysts in the pyrolysis process. The lowest EA value was attained in catalytic pyrolysis using natural zeolite (51.35–157.4 kJ/mol), followed by coal bottom ash (53.56–161.4 kJ/mol) and nickel (56.51–162.9 kJ/mol).

Thermogravimetric kinetic modelling of in-situ catalytic pyrolytic conversion of rice husk to bioenergy using rice hull ash catalyst

The thermal degradation behaviour and kinetic parameter of non-catalytic and catalytic pyrolysis of rice husk (RH) using rice hull ash (RHA) as catalyst were investigated using thermogravimetric analysis at four different heating rates of 10, 20, 50 and 100 K/min. Four different iso conversional kinetic models such as Kissinger, Friedman, Kissinger-Akahira-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) were applied in this study to calculate the activation energy (EA) and pre-exponential value (A) of the system. The EA of non-catalytic and catalytic pyrolysis was found to be in the range of 152–190 kJ/mol and 146–153 kJ/mol, respectively. The results showed that the catalytic pyrolysis of RH had resulted in a lower EA as compared to non-catalytic pyrolysis of RH and other biomass in literature. Furthermore, the high Gibb’s free energy obtained in RH implied that it has the potential to serve as a source of bioenergy production.

The effect of industrial waste coal bottom ash as catalyst in catalytic pyrolysis of rice husk for syngas production

Comparison between industrial waste coal bottom ash catalyst and commercial catalysts (nickel and natural zeolite) in catalytic pyrolysis of rice husk were investigated in this study. Characterization through X-ray fluorescence (XRF), X-ray diffraction (XRD), field emission scanning electron microscope (FESEM) and energy disperse X-ray analysis (EDX), and Brunauer–Emmett–Teller analysis (BET) were carried out to understand the physiochemical activity of the catalysts in pyrolysis of rice husk. The catalyst to rice husk ratio of 0.1 was pyrolyzed in the temperature range of 323–1173 K using thermogravimetric analyzer coupled with mass spectrometer (TGA-MS) equipment to investigate the effect of catalysts in thermal degradation behavior of biomass and syngas production. The study revealed that lowest coke formation (3.65 wt%) associated with high syngas (68.3 vol%) were attained in catalytic pyrolysis using coal bottom ash catalyst compared to nickel and natural zeolite catalysts. Moreover, the hydrogen concentration had increased 8.4 vol% in catalytic pyrolysis of rice husk using coal bottom ash catalyst compared to non-catalytic pyrolysis.

Upgrading of bio-oil from catalytic pyrolysis of pretreated rice husk over Fe-modified ZSM-5 zeolite catalyst

Catalytic pyrolysis of rice husk sample after combined washing-torrefaction pretreatment over Fe-modified ZSM-5 zeolite catalyst for bio-oil upgrading was investigated. This study shows the effects of Fe-modified ZSM-5 zeolite catalyst with different Fe loading and different pretreatment conditions from an integrated process of pretreatment and catalytic pyrolysis to improve the quality of bio-oil. The results indicated that with the increase of Fe loading, the yield of upgraded bio-oil decreased, while the relative content of hydrocarbons was enhanced obviously. The optimum Fe-modified ZSM-5 zeolite catalyst should be 4%Fe/ZSM-5 because excessive loading of Fe could affect the yield of upgraded bio-oil. Furthermore, it was found that during catalytic pyrolysis process with 4%Fe/ZSM-5, combined washing-torrefaction pretreatment had an obvious effect on promoting the production of hydrocarbons and further increasing the selectivity for BTX (benzene, toluene and xylenes), while severe torrefaction condition could significantly decrease the yield of upgraded bio-oil. Generally, combined washing-torrefaction pretreatment at mild torrefaction condition (210 and 240 °C in this study) was more suitable for upgrading of bio-oil from catalytic pyrolysis over Fe-modified ZSM-5 zeolite catalyst.

Characterization of the gas releasing behaviors of catalytic pyrolysis of rice husk using potassium over a micro-fluidized bed reactor

Influence of potassium on the gas releasing behaviors during rice husk high-temperature pyrolysis was investigated under isothermal conditions in a two stage micro-fluidized bed reactor. Reaction kinetics for generating H2, CO, CO2 and CH4 was investigated based on the Friedman and model-fitting approaches. Results indicated that different gas species had different times to start and end the gas release process, particularly at 600°C, representing different chemical routes and mechanics for generating these gas components. The resulting apparent activation energies for H2, CO, and CO2 decreased from 23.10 to 12.00kJ/mol, 15.48 to 14.03kJ/mol and 10.14 to 7.61kJ/mol respectively with an increase in potassium concentration from 0 to 0.5mol/kg, while that for CH4 increased from 16.85 to 19.40kJ/mol. The results indicated that the addition of potassium could promote the generation reactions of H2, CO and CO2 while hinder the generation reactions of CH4. The pyrolysis reaction was further found to be subject to the three-dimensional diffusion model for all the samples.

Hybrid one-dimensional nanostructure based on biomorphic porous SiO2 through in-situ catalytic pyrolysis of rice husk

Hybrid carbon nanotubes (CNTs), SiC nanowires and Si2N2O nanowires on three-dimensional (3D) hierarchical porous SiO2 were obtained from rice husk (RH) as a biomorphic structural template and raw materials through in-situ catalytic pyrolysis reaction. The samples with these one-dimensional/three-dimensional (1D/3D) combined structures were characterized by scanning electron microscopy, transmission electron microscopy, X-ray diffraction and the Brunauer-Emmett-Teller surface areas measurements. Abundant 1D nanomaterial was obtained in biomorphic porous SiO2 which presents a hierarchical macro- and microporous structure. The results showed that temperature and metal nickel organic coordination had a remarkable influence on the composition, the morphology and the quantity of produced 1D nanostructures. The CNTs were obtained at 1200°C, whereas the SiC and Si2N2O nanowires were obtained at 1300°C. The 1D/3D nano-structured samples had larger surface area than rice husk ash. The formation mechanism of 1D/3D combined nanostructure has been discussed.

Catalytic Pyrolysis of Rice Husk via Semi-Batch Reactor Using L9 Taguchi Orthogonal Array

The market demand of bio-fuel is 11,8 billion litters based on recent reported data. Hence, with the high demand of bio-fuel, the bio-fuel production utilizing rice husk can be one of the solutions. Beside, bio-oil can be produced by pyrolysis process utilizing rice husk as the feedstock. In this research, the optimization condition in producing bio-oil from rice husk by catalytic pyrolysis process was studied. The effect of catalyst type (H-β, H-Y, HZSM-5), catalyst loading (1wt%, 5wt%, 12wt%), temperature (400-500°C) and flow rate (60-100ml/min) were investigated through repetitive experiments using L9 Taguchi Orthogonal Array. The highest liquid yield of 38wt% was obtained at the optimum conditions with temperature of 500°C with nitrogen flow rate of 60ml/min and 12wt% of H-ZSM-5.

Catalytic pyrolysis of rice husk by mixing with zinc oxide: Characterization of bio-oil and its rheological behavior

The experiments on the rice husk pyrolysis were performed in a fixed-bed reactor to produce bio-oil. The effects of the different operation factors such as pyrolysis temperature、sweeping gas (N2) flow rates and ZnO catalyst on the yields of three products and the characteristics of bio-oil were investigated. The maximum bio-oil yield of 49.91% was obtained at 550°C pyrolysis temperature with a heating rate of 25°C/min and nitrogen flow rate of 150mL/min. The bio-oils yielded with and without a catalyst were characterized by FT-IR and GC/MS. The results showed that the main identified compounds of bio-oils were phenols, phenol derivatives and long-chain aliphatic compounds. It was observed that the use of catalyst decreased the bio-oil yields, but enhanced the small molecular compound yields and decreased the amount of oxygenated groups in bio-oils. A series of rheological tests were performed for the two kinds of bio-oil with cone and plate rheometer. The results indicated that both types of bio-oil were typical non-Newtonian and strongly shear thinning liquids in the flow behavior. The viscosity of the ZnO-treated bio-oil was significantly lower than that of the bio-oil without any catalyst.

Catalytic pyrolysis of rice husk for bio-oil production

Catalytic pyrolysis experiments have been carried out on Brunei rice husk (BRH) to obtain bio-oil using a fixed-bed pyrolysis rig. ZSM-5, Al-MCM-41, Al-MSU-F and Brunei rice husk ash (BRHA) were used as the catalysts for the catalytic pyrolysis experiments and comparison was done to analyse the changes in the bio-oil properties and yield. Properties of the liquid catalytic and non-catalytic bio-oil were analysed in terms of water content, pH, acid number, viscosity, density and calorific value. The bio-oil chemical composition shows that ZSM-5 increases the production of aromatic hydrocarbons and light phenols, whilst Al-MCM-41 reduces the acetic acid production. The catalytic runs increased the calorific value and water content in the bio-oil, whilst viscosity, density and acid number is decreased.