Rubberwood Research Articles

Stable Lignin-Rich Nanofibers for Binder-Free Carbon Electrodes in Supercapacitors

In this work, 1,2,4,5-benzenetetracarboxylic acid (BT) is used as a cross-linker to improve the oxidative thermostabilization of lignin-rich nanofibers so that the activated carbon nanofiber (ACNF) sheets can be prepared from lignins. As sources, we used organosolv lignins from sugarcane bagasse (LB), para rubber wood chip (LR), and palm kernel shell (LP). The addition of BT imparts hydrogen bond interactions between BT and lignin and increases the oxidation degree of lignin during the stabilization, enabling retention of nanofiber morphology after heat treatments. The preparation of activated carbon in the form of nanofibers substantially enhances the specific surface area of the materials when compared with the activated carbon powders from pure lignins. The properties of the resulting ACNFs are influenced by the structure and composition of lignins. With the synergistic effects of a small fiber diameter (688 ± 80 nm), a high content of heteroatom (O atomic content ∼5.1%), a high graphitic carbon structure (ID/IG ratio ∼0.98), a high conductivity (NI>0.1nA/A ∼3479 ± 404 pixel μm–2 at 0.5 V), and a high specific surface area (∼2195 m2 g–1), the ACNFs from LB show the highest specific capacitance of 182 F g–1 (at a current density of 0.1 A g–1 in 1.0 M H2SO4 electrolyte) with good cycling stability (95.7% capacitance retention after 6000 cycles). A maximum energy density of 31 W h kg–1 at a power density of 240 W kg–1 can be achieved from the LB/PEO/BT ACNFs. Their performance is almost comparable to that of polyacrylonitrile ACNFs. These findings demonstrate a simple and effective approach to produce lignin-based ACNFs from diverse biomass feedstock for sustainable development of renewable materials for supercapacitor electrodes.

Physical and mechanical properties of four wood species from community forests in Binjai Regency, North Sumatra

The fundamental properties of wood are significant to determine the purposes of wood used. This study aims to determine the physical and mechanical properties of four wood species namely terap (Artocarpus odoratissimus ), durian (Durio zibethinus), mindi (Melia azedarach L.), and karet or rubber wood (Hevea brasiliensis Muell. Arg) from community forests in the Binjai Regency, North Sumatra. The physical properties were determined as described in ASTM D4442 and ASTM D2395 while the mechanical properties were conducted according to ASTM D143 and BS 373. The results showed the moisture contents of four wood species ranged 12.66– 15.28%, densities 0.35–0.59 gcm-3, and specific gravities (SG) 0.33–0.55. The compression, tensile and shear strengths parallel to the grain, hardness, modulus of elasticity (MOE), and modulus of rupture (MOR) ranged 20–35 MPa, 36–80 MPa, 6.5–9.7 MPa, 1713–3226 N, 5463– 7497 MPa and 43–71 MPa, respectively. Based on the SG and MOR values, the terap wood is included in strength class IV, while the other woods are in strength class III. Meanwhile, based on the compression strength values, the terap wood is included in strength class V, durian and mindi wood are in strength class IV, while karet wood is in strength class III.

Ultrahigh-surface-area activated biocarbon based on biomass residue as a supercapacitor electrode material: Tuning pore structure using alkalis with different atom sizes

This work aims to develop an electrode material based on activated biocarbon made from rubber wood sawdust waste using alkali activating agents – KOH, NaOH, and LiOH – via a solvent-free mechanical mixing. The role of different alkali metal atom sizes plays in resulting pore structure has been studied for the first time. The influence of standard reduction potentials on the pore structure and electrochemical performance of the activated biocarbon are also investigated. The biocarbons activated with KOH or NaOH exhibit a microporous characteristic and a wide range of specific surface area of 1323–3040 m2/g, while the one activated with LiOH exhibits a mesoporous nature. The comparatively small atom size of Li and its low standard reduction potential may have caused the slow reactivity of LiOH with carbon matrix. This leads to the low specific surface area of 1134 m2/g and the formation of tiny lithium particles that could intercalate into biocarbon structure more readily than potassium or sodium particles. Mesoporosity tends to be generated by using alkali activating agent with small metal atom size and low standard reduction potential, whereas microporosity has an opposite trend. Cyclic voltammetry curves and charge-discharge profiles confirm the dominant EDLC behavior along with partial pseudocapacitance for activated biocarbons. The maximum specific capacitance is 195.3 F/g at 0.25 A/g for biocarbon activated with KOH at 4:1. This value is reduced to 69.4% of its original values at 4 A/g. The biocarbons activated with LiOH or NaOH retain the rate capability by 82.9% and 80.4%, respectively.

Pemanfaatan limbah perkebunan (kayu karet) menggunakan tungku beehives modifikasi

Biomass can be used for energy production from renewable sources. Due to the social resistance to crop burning, mixtures and pellets made from or including waste materials are a good alternative. Plantation waste becomes a problem, namely reducing land which ultimately destroys the soil and the ecosystem around the land. This waste has the potential to become charcoal that supports biomass production in Indonesia with modified beehive furnaces. The carbonized rubber charcoal has a fixed carbon content of 63% with 37% of ash, volatile and water impurities. And the redemption value in this process is around 15% which has a profit margin of 200% from the purchase capital of rubber wood waste. The carbonization process with modified beehive furnaces can be a recommendation for the manufacture of charcoal from plantation waste.

Pengaruh Kadar Perekat Terhadap Karakteristik Briket Arang Limbah Kayu Karet (Hevea brasiliensis Muell. Arg)

The study aimed to determine the effects of adhesive content on rubber wood charcoal briquette characteristics. Wood charcoal was produced using a double-drum retort kiln at > 500°C. Wood charcoals were crushed into powder and then mixed with tapioca adhesive of 5%, 10%, and 15%. The charcoal-adhesive mix was then pressed using a hydraulic press machine. For comparison, rubber wood biomass briquettes were also produced using wood particle-adhesive mix with similar adhesive content. Biomass and charcoal briquettes characteristics as physical properties (density and water absorption), chemical properties (ultimate analysis, and FTIR analysis) and energy properties (calorific value) were evaluated. The results showed that density ranged between 0.52-0.56 g/cm3, water absorption of 6.54-7.47%, C content of 82.67-84.41%, H content of 3.28-3.60%, N content of 0.67%-0.74%, and calorific value of 30.76-32.86 MJ/kg. The results of FTIR analysis showed changes in the spectrum of the wave band on the functional groups OH, CH, C≡H, C=C, and C=O, indicating the decomposition of the chemical components of rubber wood due to pyrolysis. The results prove that increasing the adhesive content can reduce the quality of briquettes. Based on physical, chemical, and energy properties, charcoal briquettes with 5% adhesive showed better characteristics than briquettes with 10% and 15% adhesive content, showing water absorption of 6.54%, C content of 84.41%, H content of 3.28%, and heating value of 32.86 MJ/kg. Keywords: adhesive content, charcoal briquette, pyrolysis, rubber wood waste, tapioca starch

In Polymerization of Environment Friendly Melamine-Urea-Glyoxal Resin in Rubber Wood for Improved Physical and Mechanical Properties

In the study, we report that a safe and simple way for upgrading inferior rubber wood through the combined modification of environment-friendly MUG resin was synthesized from glyoxal, melamine, urea, and other additives. MUG-treated wood samples were prepared with six different MUG resin concentrations (5, 15, 25, 35, 45, and 55 wt %) into the wood matrix and then heated and polymerized to form a solid and hydrophobic MUG resin in the wood scaffold, and the physico-mechanical properties were evaluated. As the MUG resin concentration increased, the weight percent gain and density increased, water uptake and leachability decreased, and the antiswelling efficiency increased at first and then decreased. MUG-treated wood sample can be prepared when the MUG resin concentration was set as 25%, and the physical properties of treated wood was optimum. Scanning electron microscopy coupled with energy-dispersive X-ray spectroscopy analysis showed that the MUG resin is widely distributed in the cell lumens and cell walls. With enhanced physico-mechanical properties, MUG-treated wood sample can be well used as a promising alternative to existing engineered wood products for structural applications.

Heat Quality Enhancement and Carbon Dioxide Emissions Reduction from Coal Burning by Combining Low-Ranked Coal with Biomass Waste as A Clean Energy Solution to Achieve Energy Security in Indonesia

Indonesia is the fifth largest coal producer in the world with coal reserves reaching 39.56 billion tonnes. Coal reserves of medium and high quality are expected to be exhausted in 2048, therefore it is necessary to utilize low-ranked coals. Low-ranked coals have a low heating value (<5,100 kcal/kg) and produce greater CO2 emissions compared to medium and high rank coals. One method to increase heating value and reduce CO2 emissions from low-ranked coals is through the Utilization of hybrid coal. Hybrid coal is low quality coal combined with biomass waste and has undergone a pyrolysis process together. The mixing and co-pyrolysis of low-ranked coal with biomass waste such as rice husk, empty palm fruit bunches, and rubber wood with a ratio of 7:3 is known to be able to increase the final product calorific value by 31.10–44.12% and reduce non-neutral CO2 emissions by 15.56–21.31%. The hybrid coal production process is highly prospective to be implemented in Indonesia, especially in Central Java, South Sumatra and South Kalimantan. The payback period from the hybrid coal industry with a production capacity range of 540 thousand to 4.5 million TPY can be achieved in 10–13 years with a net profit range of IDR 137 billion to IDR 493 billion per year and a net present value range of IDR 285 billion to IDR 1.1 trillion.

Effect of Wood Vinegar Substitutes on Acetic Acid for Coagulating Natural Para Rubber Sheets during the Drying Process

The coagulating properties of wood vinegar from para rubber wood, bamboo, and coconut shell used as a substitute for acetic acid in the production process of natural rubber (NR) sheets were investigated and considered. For the dirt and volatile content, the tensile strength at break, the percentage of elongation at break, and the 300% modulus, the results showed that the types of wood vinegar coagulants were not significantly different from acetic acid. However, the Mooney viscosity and plasticity retention index (PRI) properties were significantly different from those of acetic acid. The NR sheet temperature increased rapidly during the first hour after the drying process started due to heat transfer from the hot air. Afterward, the temperature of the NR sheet samples began to stabilize. When the drying process started, the drying temperature was increased, so the trend was reducing the drying time. For the yellowness index (YI) value, the increase in the YI value was related to the type of coagulating material, the increase in the airspeed, and the drying temperature. The dried sheet samples using para rubber wood vinegar as the coagulating material had a color value at the same level as acetic acid and the referent. However, the bamboo and coconut shell wood vinegars were at a lower level. In comparing the YI value data between the experimental results and prediction values, the second-degree model had a better fit in prediction than the zero-degree and first-degree models. This result was confirmed by the higher mean of the coefficient of determination. The dried sheet product coagulated by using wood vinegar had fungus growth prior to supplying it to the customer.

Bioconversion of renewable lignocellulosic biomass into multicomponent substrate via pressurized hot water pretreatment for bioplastic polyhydroxyalkanoate accumulation

The pretreatment of lignocellulosic biomass (LB) has become an important process to reduce the cost of polyhydroxyalkanoate (PHA) production. In this study, an economical and effective pressurized hot water pretreatment was used to investigate on bioconversion of four typical LB (rubber wood, sugarcane bagasse, sorghum stalk, cassava stalk) into reducing sugar, then as feedstock to accumulate PHA by mixed microbial cultures. The results showed that pretreatment changed the surface morphology of LB and further improved saccharification efficiency. The maximum reducing sugar yield of 620.7 mg·g−1 (438.7 mg·g−1 glucose and 178.0 mg·g−1 xylose) was obtained by rubber wood. The conversion of cellulose and hemicellulose reached 83.10% and 78.22%. Moreover, PHA content reached the maximum of 773.2 mg COD·L−1 in the operation cycle of 24 h. The results demonstrated that hot water pretreatment was an effective physical process to improve the saccharification efficiency of LB for reducing the cost of PHA.

Particle-bound organic and elemental carbons for source identification of PM < 0.1 µm from biomass combustion

Atmospheric nanoparticles (PM < 0.1 µm) are a major cause of environmental problems and also affect health risk. To control and reduce these problems, sources identification of atmospheric particulates is necessary. Combustion of bituminous coal and biomass including rubber wood, palm kernel, palm fiber, rice stubble, rice straw, maize residue, sugarcane leaves and sugarcane bagasse, which are considered as sources of air quality problems in many countries, was performed. Emissions of particle-bound chemical components including organic carbon (OC), elemental carbon (EC), water-soluble ions (NH4+, Cl−, NO3−, SO42−), elements (Ca, K, Mg, Na) and heavy metals (Cd, Cr, Ni, Pb) were investigated. The results revealed that PM < 0.1 µm from all samples was dominated by the OC component (>50%) with minor contribution from EC (3%-12%). The higher fraction of carbonaceous components was found in the particulates with smaller sizes, and lignin content may relate to concentration of pyrolyzed organic carbon (PyOC) resulting in the differences of OC/EC values. PM emitted from burning palm fiber and rice stubble showed high values of OC/EC and also high PyOC. Non-carbonaceous components such as Cl−, Cr, Ca, Cd, Ni, Na and Mg may be useful as source indicators, but they did not show any correlation with the size of PM.

Guidelines for Development of Area-Based Plantation of Rubber Commodity in Musi Rawas

There has not been a good integration among the central, provincial, and regional levels in the allocation of the budget, thus making the impact of plantation development activities less effective and efficient. This study aimed to analyze the potential of the region and create a pattern for the development of rubber commodity plantations in Musi Rawas District. This study was conducted by analyzing the data and literature review, conducting focus group discussions, mapping and digitizing the potential for rubber commodities using satellite imagery. With the position of the region that is included in the growing stage, the development of the area is directed first for on-farm development. The development of the region is carried out by increasing the production and productivity of rubber plants in Musi Rawas District by replanting and intensifying the rubber plants. The activity strategy focuses more on how to increase the productivity of rubber plants so as to produce high quality claret processing materials (BOKAR) and rubber wood. The development strategy is centered in Tuah Negeri sub-district as the center of the Area and other surrounding sub-districts as supporting Areas. Therefore, in order to achieve these production targets, the strategy taken in developing rubber-based plantation areas is the incorporation and strengthening of the rubber agribusiness system.

Aktivitas Pelapukan Kayu Inokulum Ganoderma boninense pada Tumpangsari Bibit Kelapa Sawit dan Talas-Talasan

Basal stem rot of oil palm caused by Ganoderma boninense is difficult to be controlled due to abundance of inoculum sources in the field. This study was aimed to determined effects of taro plants viz. Belitung taro ( Xanthosoma sagittifolium ), Bogor taro ( Colocasia esculenta ), and Japanese taro ( Colocasia esculenta var. antiquorum) on decay of G. boninense inocula. Pathogen inocula as rubber wood block (RWB) colonized by G. boninense was attached with main roots of oil palm seedling and buried into soil of oil palm seedling (monoculture), mixed planting of oil palm and taro plants, or of taro plants monoculture. Burying of pathogen inocula for 3 and 6 months on taro plant resulted in 2.1 times higher decay of RWB compared than oil palm monoculture. Increasing of decay also exhibited on mixed cropping system, but it was slightly lower than on oil palm monoculture. This result suggesting the benefit of taro plants either planted under monoculture or mixed cropping to fasten decomposition of infected wood debris as an inoculum source of G. boninense .

Pengaruh Tumpangsari dengan Tanaman Rimpang Terhadap Infeksi Awal Ganoderma boninense pada Bibit Kelapa Sawit (Elaeis guineensis)

Basal stem rot (BSR) caused by white decay fungus, Ganoderma boninense is known to cause significant losses in oil palm plantation in Southeast Asia. This study determined the effect of oil palm mixed planting with rhizomatous plants, galangal ( Alpinia galangal ), Java curcumin ( Curcuma longa ), or ginger ( Zingiber officinale ) on initial infection of BSR. Plants were inoculated by attachment of rubber wood block colonized with G. boninense to the main roots. Infection was measured as length of root necrosis and confirmed by culturing on Ganoderma selective medium. Infection was also assessed by total activity of ligninase as measured by RBBR decolorization. The results showed that G. boninense infection at 1-month-post inoculation was lower on mixed planting with all rhizomatous plants, and the suppression of infection was still occured in mixed planting with galangal. Total activity of ligninase on oil palm roots was delayed on mixed planting compared to that of higher activity on single planting at 1-month-post inoculation. This result highlights benefit of mixed planting of oil palm with rhizomatous plants in delaying initial infection of BSR patogen.

Prediction of Size Distribution and Mass Concentration of Smoke Particles on Moisture Content and Combustion Period from Para Rubber Wood Burning

The size distribution and total particle mass concentration (TPMC) of smoke particles from para rubber wood (Hevea brasiliensis) combustion in the ribbed smoked sheet (RSS) process were studied. In this experiment, temperature data values of para rubber wood combustion were recorded at 500 mm above the base of the fire by K-type thermocouples. The wood moisture content and wood combustion period were used to find and improve an equation of smoke particle size distribution (SPSD) and TPMC by the response surface method (RSM). An eight-stage Andersen air sampler and a high-volume sampler were used to measure and calculate SPSD and TPMC, respectively. Resulting data in this experiment showed that TPMC ranged from 3.12 to 77.42 mg/m3. SPSD was single mode in which MMAD, mass median aerodynamic diameter, ranged from 0.64 to 1.27 microns for para wood with moisture content ranging from 31.5 to 89.7% dry weight basis. The combustion period and moisture content of para wood have a direct effect on the change of temperature data above the base of the fire and the TPMC and MMAD values. For predicting TPMC and MMAD values by the para wood moisture contents in each combustion period, the results found that the second-degree model was a better plot than the first-degree model, confirmed by higher values of the coefficient of determination (R2).

Response Surface Methodology to predict the performance and emission characteristics of gas-diesel engine working on producer gases of non-uniform calorific values

Energy generation through gasification technology has received significant attention from policy makers and researchers. To promote government policies on biomass and utilize energy source that are abundantly available in rural areas, suitable technologies must be developed with a focus on popular applications in a place. The biomass in rural areas differs from place to place and they may not generate uniform calorific value (CV) of producer gas (PG). The quality of PG is essential to run engines of power generators with required performance. Hence, in this study, a mathematical investigation was performed on a dual-fuel diesel engine for CV of PG from 3.4 to 6.6 MJ/Nm3. The major objective was to find the impact of the variation in CV of PG from coir pith, rice husk, rubber wood, coconut shell and rubber seed kernel shell on the performance of the engine. Response Surface methodology with suitable tools had been used for developing the model. The model predicted the optimum thermal efficiency, specific energy consumption and diesel replacement rate as 25.8%, 13.95 MJ/kWh and 59.04% respectively while calorific value of PG was 6.57 MJ/Nm3. However, CO and NOx emissions were found increasing with the increase in calorific value of PG.

Sulfate removal using rubber wood ash to enhance biogas production from sulfate-rich wastewater generated from a concentrated latex factory

Skim latex serum (SLS) is high-strength wastewater generated from latex processing. Anaerobic treatment of SLS can be enhanced by reducing the sulfate content, which is an inhibitor in the biogas production system. This study investigates the effect of mixing time and rubber wood ash (RWA) loading on sulfate removal from SLS. The optimum sulfate removal efficiency of 42 % was achieved when 10 g/L of RWA was loaded for 10 min. The biogas production efficiency from both desulfated and raw SLS was investigated. The highest 306.36 m L-CH4/g-COD of methane production yield was achieved from desulfated SLS using RWA loading of 10 g/L (DSLS10), which is 16 % higher than the yield generated using raw SLS as a substrate. Moreover, hydrogen sulfide content in the biogas produced by desulfated SLS was two times lower than raw SLS. The results indicate removing sulfate from SLS using RWA before feeding to the anaerobic digestion enhanced biogas production yield and quality.

RETRACTED ARTICLE: Recycling of waste crumb rubber into a commercial materials

Nowadays, there is an increase in heavy vehicles. These vehicles come with more wheels which has consequently increased tyre usage. Tyre rubber material is non-biodegradable. It takes more than a century to degrade. Its lifetime ensures that the tyres in heavy vehicles be changed only once in 4 or 5 years. However, it is noticed that there is an increase in scrap tyres every year. The non-degrading nature of tyre affects the environment and the whole ecosystem. Sometimes, dumping or storing of these old tyres in one place increases the breeding of mosquitos, insects, and bacteria. This causes infectious diseases in people. Wood waste in the form of powder is pressed into crumb rubber using hot pressing technology. The wood rubber composite was taken from crumb rubber and waste wood has excellent mechanical properties. After performing the tensile, tear, and thermal tests, it was found that the tensile strength of commercial material is 7.848 Mpa which is closer to virgin rubber (10 Mpa). The yield/break force was found to be > 120 N. The percentage elongation and yield elongation is found to be nearly 180% which is closer to the properties of virgin rubber. In addition to the mechanical properties, it also has a water absorption rate which is closer to 1 part in a thousand and chemical resistance rate shows very little erosion similar to virgin rubber. This makes fabricated recycled crumb rubber useful for commercial applications like flooring, sound insulation, heavy-duty performance, and vibration absorption too. In this work, crumb rubber has been selected to reduce the usage of natural raw materials.

Optimization of carriers and packaging for effective biofertilizers to enhance Oryza sativa L. growth in paddy soil

For a biofertilizer to promote plant growth after application, cell survival during storage must be ensured, while the carrier formulation and packaging are important factors during storage. This study aimed to optimize the ratio of rubber wood ash (RWA), decanter cake (DCC), rice husk ash (RHA), and spent coffee grounds (SCG) as a mixed carrier of biofertilizer of purple non-sulfur bacteria (PNSB), Rhodopseudomonas palustris and Rubrivivax gelatinosus. Different packaging materials, and different sealing methods were investigated. The phytotoxicity of PNSB biofertilizers in a solid form, and their effectiveness to enhance rice (Oryza sativa L.) seedling growth in paddy soil were also investigated in comparison with a liquid form. A mixed carrier of RWA, DCC, RHA and SCG at a ratio of 3:4:2:1 most effectively maintained viability. After 6-month storage at 25 ± 3 °C, PNSB population of a mixed carrier containing R. palustris at roughly 10 log CFU/g in nylon-linear low density polyethylene (nylon-LLDPE) bags that were vacuum sealed at 500 W decreased by only 3 log cycles compared with 7 log cycles in the control. The PNSB biofertilizers, each genus and a mixed culture at 1: 1, either in solid or liquid form at their optimal dilutions showed no phytotoxicity. However, the mixed carrier itself as a control was slightly toxic. At these optimal dilutions, all PNSB biofertilizers in both liquid and solid formulations significantly increased rice growth in paddy soil compared with controls. A suitable mix of agro-industrial waste and suitable packing prolonged the shelf-life and potency of PNSB biofertilizers.

The Effect of Biomass Shapes on Combustion Characteristic in Updraft Chamber

Combustion of agricultural residues and wastes for energy applications is still popular. However, combustion of biomass with different shapes leads to many side effects such as agglomeration, emission and incomplete combustion. The aim of this study was therefore to investigate the effects of biomass shapes on combustion characteristics in an updraft combustion chamber. The rubber wood chip, coconut shell, oil palm empty fruit bunch, corn straw, rubber wood sawdust, and mixed palm cake were used as fuel and they were categorized as 3 shapes namely, chip shape, fiber shape, and powder shape. The biomass sample was combusted in simple cylindrical shape combustion chamber. The diameter of combustion chamber was 20 cm and its height was 160 cm. The biomass sample (moisture content below 20%) with amount of 1 kg was used to perform the experiment. The ambient air that had velocity of 0.50, 0.75 and 1.00 m/s (corresponding to an equivalence ratio of 1-3.5) was supplied to combustion chamber. The temperature at different positions along combustion chamber height and the properties of flue gases (carbon monoxide) were then measured. The results showed that the biomass shape had effect on combustion characteristics. Combustion of fiber shape biomass led to low combustion temperature, while the carbon monoxide in flue gases was high. This indicates the improper combustion process. The chip shape biomass was well combusted at a higher air velocity and the flue gases had lowest carbon monoxide. The highest combustion temperature was obtained from combustion of powder shape biomass. However, it led to the problem of unburned biomass such in case of sawdust. This is because the sawdust powder was carried from combustion chamber before burning completely.

Structural evolution of rubber-wood char under different pyrolysis conditions

In order to explore the effect of different pyrolysis conditio ns on the structural characteristics of rubber wood biomass pyrolysis, rubber wood char was prepared under fast pyrolysis and slow pyrolysis conditions. The char was analyzed by BET, SEM, FT-IR and Raman spectroscopy to explore the effects of different pyrolysis conditions on pore characteristics, surface structure and chemical structure. The results showed that the nitrogen isothermal adsorption/desorption curves of slow pyrolysis at 900°C are obviously different, and the char structure has a certain amount of mesopores and macropores. With the pyrolysis temperature increased, the alkane side chain of rubber wood char broke, and formeda large number of active sites, which promoted the condensation of small aromatic rings into large aromatic ring structures, and deepened the aromatization of char structures. The rapid pyrolysis method causes the content of the small aromatic ring structure to be greater than that of the large aromatic ring structure at low temperature. The slow pyrolysis method causes the increase of the large aromatic ring structure to be greater than that of the small aromatic ring at a lower temperature contrarily.