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    30 May 2021, Volume 55 Issue 3 Previous Issue   
    Research Report
    Effect of Pyrolysis Temperature on Structures of Chars Forming from Cellulose and Lignin
    Dichao WU, Chao CHEN, Xinglong HOU, Kang SUN
    2021, 55 (3):  1-9.  doi: 10.3969/j.issn.1673-5854.2021.03.001
    Abstract ( 174 )   HTML ( 9107 )   PDF (13930KB) ( 238 )   Save

    This work focused with the assistance of the mechanism of pyrolysis carbonization of cellulose, lignin and hemicellulose were analysed by TG, TEM, Raman, XRD, and FT-IR based on the molecular restructuring behavior of three major components of cellulose, lignin and hemicellulose during pyrolysis. The results showed that hemicellulose was completely decomposed during pyrolysis; molecular rearrangement occurred during the pyrolysis of cellulose, forming crystallized areas in biomass char; lignin had a very complex cross-linked structure, melted during pyrolysis, forming amorphous carbon areas in biomass char. During the charring process, cellulose undergone mainly dehydration reactions when the temperature was lower than 200 ℃, and the temperature range of 200 to 400 ℃ was the main stage of pyrolysis; lignin was relatively structurally stable in the studied temperature range(200-500 ℃), with only partial structural transformation occurring while softening and melting.

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    Immobilization of Thermostable Recombinant β-Glucosidase and Its Application in Transformation of Flavonol Glycosides
    Jingcong XIE, Hao XU, Ning ZHANG, Jing YANG, Jian ZHAO
    2021, 55 (3):  10-16.  doi: 10.3969/j.issn.1673-5854.2021.03.002
    Abstract ( 83 )   HTML ( 40 )   PDF (607KB) ( 98 )   Save

    In order to increase the efficiency of the enzymatic conversion of flavonol glycosides and reduce the cost of the enzyme, the immobilization conditions of recombinant thermostable β-glucosidase were investigated. The differences of enzymatic properties between immobilized enzyme and free enzyme were compared, and the conversion curves and conversion efficiency of the immobilized enzyme on transforming three kinds of flavonol glycosides were obtained. The results showed that the optimal immobilization conditions were sodium alginate 1.5%, calcium chloride 2%, glutaraldehyde 1.25%, and pellets solidifying time 2.5 h under room temperature and pH 6.0. Under these conditions, enzyme activity was 0.64 U/mg, and the immobilization rate was 62.5%. The pH stability and temperature stability of the immobilized β-glucosidase were better than those of the free β-glucosidase and it retained more than 55% residual activity after reusing for 20 times. The isoquercetin, daidzin, and icariside I were transformed into their aglycones with high efficiency though immobilized β-glucosidase and the conversion rates were 99.37%, 97.21% and 97.93%, respectively, and the yields of quercetin, daidzein and icariin were 0.776, 1.091 and 0.714 g/(L·h), respectively.

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    Research and Production Demonstration for Water Saving and Emission Reduction Green Processing Technology of Oleoresin
    Shichao XU, Yuxiang CHEN, Xin LING, Guangping ZHOU
    2021, 55 (3):  17-22.  doi: 10.3969/j.issn.1673-5854.2021.03.003
    Abstract ( 73 )   HTML ( 50 )   PDF (444KB) ( 111 )   Save

    Oleoresin is a characteristic high output forestry resource in China and its main processing products such as rosin and turpentine are important forest-based chemical raw materials. However, even there are many rosin production enterprises in our country, the processing technology of oleoresin had almost no improvement in recent years. The water-consumption and the loss of oleoresin in these processes are still very high. To solve these problems, this paper reported a watering-saving and emission-reduction green processing technology for oleoresin. The water consumption was evidently reduced through water-saving oleoresin transportation, oleoresin melting, oleoresin impurity removal, recycling of the middle-layer oleoresin liquid and purified oleoresin distillation technologies. Through relevant research and production demonstrations, the water consumption for the oleoresin process of Pinus yunnanensis/Pinus kesiya was 0.759 ton per ton (oleoresin), and that of Pinus massoniana was 0.836 ton per ton, which was nearly 70% less than the existing high-quality rosin processing enterprises. The removal rate of mechanical impurities in middle-layer oleoresin liquid was over 90%.

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    Effect of Gasification Temperature of Circulating Fluidized Bed on Solid Product Feature of Rice Husk Gasification
    Xiaojin HU, Tao YANG, Sanju LIU, Jun LIU, Shoujun ZHANG, Yirui LI
    2021, 55 (3):  23-28.  doi: 10.3969/j.issn.1673-5854.2021.03.004
    Abstract ( 91 )   HTML ( 63 )   PDF (2470KB) ( 129 )   Save

    In order to resolve the utilization of solid-phase product generated in the process of coal-fired coupling biomass circulating fluidized bed gasification power generation, the effect of gasification temperature on fuel gas components, carbon content, specific surface area, micromorphology and adsorption capacity of the solid-phase products was investigated in Xiangyang power plant 6# unit with rice husk as the raw material. The results showed that, CO and H2 contents in the gas increased first and then decreased with the increase of gasification temperature. When the temperature was 775 ℃, CO and H2 contents arrived the highest values of 18.79% and 7.83%. During 625-775 ℃, a high calorific value of fuel gas, as well as the carbon content of solid-phase product, could be obtained. At a lower gasification temperature, a well-developed pore structure, an increased number of pores, and a medium thickness of pore wall could form and the larger specific surface area of solid-phase products increased by decreasing of the temperature. There was a linear correlation between the iodine adsorption value and the specific surface area. At 625 ℃, the maximum specific surface area of solid-phase products could be reached(145.3 m2/g), as well as the maximum adsorption capacity of iodine of 265 mg/g. The solid products are promising in the fields with a high consumption of adsorption materials while a relatively low demand for adsorption capacity.

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    Preparation of Furfural and Levulinic Acid from Hybrid Pennisetum Hydrolysis in Biphasic Hydrated Molten Salt System
    Song KU, Xuesong TAN, Rundong LI, Xinshu ZHUANG, Zhenhong YUAN
    2021, 55 (3):  29-34.  doi: 10.3969/j.issn.1673-5854.2021.03.005
    Abstract ( 73 )   HTML ( 64 )   PDF (515KB) ( 131 )   Save

    Hybrid Pennisetum was used as raw material and extracted firstly by toluene-ethanol. Diethyl phthalate was used as the organic phase and added to the acidic lithium bromide solution with the sulfuric acid concentration of 0.05 mol/L to form lithium bromide hydrated molten salt-diethyl biphasic system. And then, the raw materials were placed in the biphasic system for hydrolysis to produce furfural(FF) and levulinic acid(LA). The effects of temperature, acid concentration, reaction time and organic phase volume on the yield of FF and LA were investigated.The experimental results showed that when the system was an acidic lithium bromide solution with the sulfuric acid concentration of 0.05 mol/L, the solid-to-liquid ratio of the extracted Pennisetum to the acidic lithium bromide volume was 1:20(g: mL), the volume of the diethyl phthalate was 20 mL, 1 g of the extracted Pennisetum was used as raw material, the reaction temperature was 160 ℃, and the reaction time was 120 minutes, the yield of FF was 65.17%, and the yield of LA was 10.48%. Under the same conditions, when the acidic lithium bromide volume was 30 mL and the organic phase volume was 10 mL, the yield of FF was 60.74%, and the yield of LA was as high as 41.30%. More than 80% of FF was dissolved in the organic phase, and more than 90% of LA was dissolved in the hydrated molten salt phase. The technology could realize the synchronous preparation and effective separation of FF and LA, and could effectively reduce production costs and shorten the process flow, which provided a reference for the simultaneous preparation of furfural and levulinic acid from cellulosic biomass.

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    Effect of CaCl2on Physicochemical Properties of Cotton Straw Carbon
    Jingtao DAI, Ying YANG, Lina WANG
    2021, 55 (3):  35-41.  doi: 10.3969/j.issn.1673-5854.2021.03.006
    Abstract ( 69 )   HTML ( 32 )   PDF (7295KB) ( 58 )   Save

    The effects of anhydrous calcium chloride on the physicochemical properties of cotton straw based porous biochar were studied with cotton straw as raw material under different temperature. The morphology and structure were characterized by simultaneous thermal analysis(TG-DSC), X-ray diffraction(XRD), Raman spectroscopy(Raman), scanning electron microscopy(SEM), transmission electron microscopy(TEM) and N2 adsorption-desorption analysis. The TG results showed when the pyrolysis temperature reached 500 ℃, the weight loss of the samples was less, so 550-750 ℃ was selected as the pyrolysis temperature range. The experimental results showed that the samples prepared by the two pyrolysis methods(direct pyrolysis and CaCl2 activation) were amorphous carbon structure. During 550-750 ℃, for direct pyrolysis, the ID/IG values of Roman analysis were about 0.93, the maximum specific surface area was 2.09 m2/g and the average pore size was 7.21 nm; for CaCl2 activation, the ID/IG values were about 0.85, the maximum specific surface area was 487.68 m2/g and the average pore size was 5.97 nm. And the samples prepared by the activation method are better than the samples prepared by the direct pyrolysis method in the degree of graphitization, specific surface area and pore size, while the samples prepared by the direct pyrolysis method had larger pore size, high degree of disorder and good stability.

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    Debranching Modification of Pullulanase of Gleditsia sinensis Polysaccharide
    Changling ZHU, Peng LEI, Fenglun ZHANG, Huanshi ZHANG
    2021, 55 (3):  42-46.  doi: 10.3969/j.issn.1673-5854.2021.03.007
    Abstract ( 53 )   HTML ( 32 )   PDF (625KB) ( 88 )   Save

    The debranching effect of pullulanase on Gleditsia sinensis polysaccharide(GSP) was investigated, and the compounding properties of modified Gleditsia sinensis polysaccharide(MGSP) gum and xanthan gum were studied. The results showed that MGSP with 23.4% galactose content was obtained after treating for 6 h(the content of galactose in GSP was 28.2%), and pullulanase modification did not change the main structure and glycosidic bond configuration of the main chain of the polysaccharide, but reduced the galactose content of the side chain in the molecular chain of GSP; when the MGSP was mixed with xanthan gum, it showed a significant synergistic effect, and showed the characteristic of strong gel with high elasticity. When the MGSP was combined with xanthan gum, the compound ratio played a key role in the performance of the compound, when the mass ratio of MGSP and xanthan gum was 6:4, the elastic modulus of the compound gum was the largest(112.3 Pa), and the effect of the compound ratio on the viscosity modulus of the compound gum was relatively large.

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    Simulation Study of Biomass Two-stage Enriched Air Gasification-Gas Turbine Combustion for Power Generation
    Shaohua LIANG, Taiyan ZHANG, Yongling YAO, Chengbin LU, Bin XU, Miaomiao NIU
    2021, 55 (3):  47-54.  doi: 10.3969/j.issn.1673-5854.2021.03.008
    Abstract ( 70 )   HTML ( 63 )   PDF (952KB) ( 182 )   Save

    For the efficient and clean utilization of biomass energy, a two-stage enriched air gasification system was designed to improve the gas quality. The obtained clean high calorific combustible gas was used in gas turbine for power generation. The influence of the oxygen percentage of enriched air and secondary gasification temperature on the gasification performance and gas turbine operating characteristic were analyzed based on the Aspen Plus simulation. The results confirmed the feasibility of application of biomass gasification gas in gas turbines. And it was found that increasing oxygen percentage could efficiently improve the combustible gas quality and the system power generation efficiency. The secondary gasification temperature in the two-stage gasification system could cause slight decrease of gasification efficiency and power generation efficiency. Thus the gasification temperatue should be controlled in a reasonable range.When the gasification temperature was high enough for complete ash melting and separation, lower temperature could be chosen for saving energy. The optimum oxygen percentage of enriched air for two-stage gasification system was 50%-60%. When the oxygen percentage was 60% and the gasification temperature was 1 200 ℃, the power generation efficiency(ηt) reached maximum(34%), and the lower calorific value of the combustible gas was 9.54 MJ/m3 and the two-stage gasification efficiency(ηCGE) was 78.65%.

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    Response Surface Optimization of Preparation of Aviation Kerosene from Jatropha Oil Catalyzed by Pd-Al2O3-BEA
    Ruifan LI, Yubao CHEN, Yongyan ZHAO, Shiyun ZHUANG, Wenjie ZHANG
    2021, 55 (3):  55-61.  doi: 10.3969/j.issn.1673-5854.2021.03.009
    Abstract ( 67 )   HTML ( 95 )   PDF (970KB) ( 167 )   Save

    The catalyst loaded with Pd as an active metal and combined Al2O3 and molecular sieve BEA as carrier was prepared, and it was used to catalyze the one-step hydrogenation of Jatropha oil in a high-pressure reactor to produce aviation kerosene. On the basis of single factor experiments, the Box-Behnken central combined experimental design response surface method was used to optimize the process parameters (reaction temperature, pressure, speed) with the deoxygenation rate of fatty acids in Jatropha oil and the selectivity of C8-C16 hydrocarbons as indexes. The results showed that the effect order of the C8-C16 selectivity was reaction temperature>speed>pressure, and the optimal reaction conditions were 310 ℃, pressure 2.48 MPa, and rotating speed 90 r/min. Under these condition, total hydrocarbons in aviation kerosene contained 99.98%, of which C8-C16 hydrocarbons was 73.86%.

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    Review Comment
    Research Progress on Lignin Degradation by Microorganism
    Jing YANG, Jianchun JIANG, Ning ZHANG, Hao XU, Jingcong XIE, Jian ZHAO
    2021, 55 (3):  62-70.  doi: 10.3969/j.issn.1673-5854.2021.03.010
    Abstract ( 148 )   HTML ( 11391 )   PDF (694KB) ( 245 )   Save

    Lignocellulose is the most abundant renewable biomass resource on the earth and cellulose is one of the three components of lignocellulose and is important raw material for the production of bio-based materials, fuels and chemicals. However, the complex chemical structure of lignin limits the application of lignocellulose. Conventional physical, chemical and physical-chemical lignin degradation methods often require high temperature and high pressure conditions, resulting in high energy consumption, inhibitors and environmental pollution. The biocatalysis process mediated by microorganisms is usually carried out under mild conditions, which can reduce energy input and provide a more specific and effective choice for the utilization of lignin. The degradation of lignin by fungi, represented by white-rot fungi, presents the problems of long pretreatment cycle and poor adaptability to the environment. Bacterium becomes the future potential of lignin degradation, owing to its rapid proliferation, profound environmental adaptability and easy genetic manipulation. This review introduced the progress of microbial degradation of lignin on the base of chemical structure, and mainly analyzed the microorganisms (fungi and bacteria), degrading enzymes (peroxidase and laccase) as well as the degradation mechanism. Besides, the applications of microbial degraded lignin in lipids, bioplastics, vanillin and wastewater treatment were summarized and the future development was suggested.

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