Papers by Keyword: Pyrolysis Temperature

Abstract: Carbon molecular sieve membranes were prepared by pyrolysis of novolac type phenol-formaldehyde resin. The influences of pyrolysis temperature on membrane properties were investigated. By raising the pyrolysis temperature from 600 oC to 700 oC, the number of pores and effective pore size increased, thereby making the carbon membrane more productive but less selective. When the pyrolysis temperature from 700 oC to 900 oC, the effective pore size was reduced by sinter effect, thereby the gas permeation rate decreased and selectivity increased. The carbon membranes were characterized by elemental analysis, X-ray diffraction (XRD), and CO₂ adsorption. H₂, N₂, CH₄, and O₂ were used for pure gas tests to evaluate membrane performance.

Abstract: This paper reported the fragmentation behavior of lignite coal particles during coal pyrolysis in fluidized bed reactor at temperature of 300°C,350°C,600°C,650°C. The particles with size of 2-4mm,4-6mm and 7-10mm pyrolyzed under N₂ atmosphere. The fragments were recovered by hopper, cooled to the ambient temperature and sieved in different ranks. Experimental results show that with the increasing of temperature and initial coal size due to internal overpressure induced by volatiles releasing and thermal stress caused by thermal gradient of coal intra-particles the intensity of fragmentation was enhanced monotonously, the number of fragments increased sharply and the average size of fragments declined.

Abstract: This research studies the effect of cadmium adsorption-desorption kinetics with different pyrolysis temperature biochar. The biochar which derived from rice husk at 300°C, 400°C, 500°C temperature for 30 minutes were added into Cd²⁺ solutions of 0.5 mg/L, 2.5 mg/L and 5 mg/L respectively. The optimal model of cadmium adsorption desorption kinetic behavior is the Level 1 dynamic equation. Indicates the increasing Cd²⁺ adsorption ability of biochar with pyrolysis temperature rising. Biochar also shortens adsorption process at relatively low Cd²⁺ initical concentrations.

Abstract: The article studies the pyrolytic properties of the binderless hot-briquetted lignite in East Mongolia during the process of middle-temperature and low-temperature pyrolysis, mainly on the law of semi-coke characteristics and the tar extracts, pyrolysis water, gas velocity, gas contents at different temperature, meanwhile compared the pyrolysis characteristics of the raw coal and briquette. The research shows that as the temperature increasing, the semi-coke yield obtained by pyrolysis of lignite briquette is nearly 6% higher than raw coal, Tar releasing is approximately equal to raw coal, the pyrolysis water yield of raw coal is about13.85% higher than the briquette, the gas yield of briquette is about 7% higher than raw coal, gas velocity of briquette is higher than raw coal, calorific value of briquette gas is about 3 MJ/Nm³ higher than raw coal, gas composition rules are approximately equal, and both with a high content of CO and H₂, and as well as suitable for synthesis gas. The main process of binderless briquetting is to remove moisture from coal samples. It relatively makes gas releasing process and water-oil separation more easily and makes the gas calorific value improved.

Abstract: The Yining char samples were prepared in following conditions that raw coal particle size was in range 5-6mm and pyrolysis final temperature was 900oC, 1000oC and 1100oC, respectively, with a heating rate 20oC/min under atmospheric pressure. The gasification reactivity of chars was performed by thermogravimetric analysis (TGA) at 900oC in steam, CO2 and steam/CO2 mixture, respectively. The results show that the gasification reactivity of chars decreases with the increasing of pyrolysis final temperatures and there is synergistic effect between steam and CO2 during co-gasification that influences the char reactivity. The reason may be explained by char structure change, which FTIR showed that –CH3 and –O–CH3 decreased and even disappeared and XRD analysis suggested that the thickness of microcrystalline Lc, the values of microcrystalline diameter La and the aromatic of char fa became larger with increasing pyrolysis temperature.

Abstract: Temperature-programmed pyrolysis of SL-lignite from Xilinhaote was investigated. The solid and gaseous pyrolysates were analyzed by means of gas chromatography(GC) and X-ray diffraction(XRD). The weight percents of surface moisture, ash, C, H and S increase with increasing the pyrolysis temperature in solid pyrolysates, while the volatile matter is contrary. The cracking reaction occurs before 600°C, the consolidation reaction happens between 600°C and 650°C, while the polycondensation or secondary reaction appears after 650°C. Calcium sulfide is formed by the process of decomposition of calcium sulphates at 900°C. The solid pyrolysates become more graphitic with increasing the pyrolysis temperature.

Abstract: Sino Fibers Reinforced BN Wave-Transparent Composites (SiNO_f/BN) Were Fabricated through Precursor Infiltration and Pyrolysis (PIP) Method Using Borazine as Precursor. The Effect of Pyrolysis Temperature on the Densification Behavior, Microstructures, Mechanical Properties and Dielectric Properties of the Composites Was Investigated. The Results Suggest that with the Increase of the Pyrolysis Temperature from 800 °C to 1000 °C, the Density, Mechanical Properties and Dielectric Constant of the Composites Are Increased, but the Infiltration Efficiency Varies Little. At the Pyrolysis Temperature of 1000 °C, the Density of SiNO_f/BN Composites is 1.84 g∙cm^-3 and the Flexural Strength and Elastic Modulus Are 148.2 MPa and 26.2 GPa Respectively. The Dielectric Properties, Including Dielectric Constant of 3-4 and Dielectric Loss Angle Tangent of below 7×10^-3, Obtained at Three Different Temperatures Are Excellent for the SiNO_f/BN Composites Applied as Wave-Transparent Materials.

Abstract: The influence of F/P on structure and thermal property of resin was studied. Six resins were synthesized with different molar ratios of F/P. These resins were cured by means of temperature and without catalyst. The characterization of the resin was done by Fourier transform infrared spectroscopy (FTIR), thermo gravimetric analysis (TGA) and differential thermo gravimetric analysis (DTG). From the thermal properties of fully cured resins, characteristic properties including pyrolysis temperature and char yield were obtained. A maximum in the benzene ring substitutions, methylene bridge and the result of the thermal properties allow us to say that the resin with F/P molar ratio 1.2 has the highest crosslinking density and highest char yield, over 73%.

Abstract: Pyramid sharp pyrolysis flame is a new method for carbon nanotubes synthesis. Oxy-acetylene flame outside the frustum of pyramid sharp reactor provides the necessary high temperature circumstance for carbon nanotubes synthesis, while inside the interior mixture of CO, H2, He, and iron pentacarbonyl (Fe(CO)5) is heated. CO is used as the source of carbon, Fe(CO)5 as the source of catalyst precursor. Special structure of the frustum of pyramid sharp reactor makes the oxy-acetylene flame folded gradually above the reactor. And it meets the condition that the interior mixture which has reacted initially under high temperature and will flow out of reactor avoids exposing to air completely and burning abundantly. Immersing a sampling substrate into the incomplete burning flame can gain carbon nanotubes. By adjusting the distance between the oxy-acetylene flame jet and the synthesis area, achieved the purpose that just changing one factor of synthesis or pyrolysis temperature while the other one constant, then respectively studied the effects of them on experimental. The perfect synthesis temperature in experimental is about 595°C, while the pyrolysis temperature is about 1000°C.

Abstract: Carbon nanolines on carbon cloth were prepared via a two-step method at 600-900°C for 30 min in a horizontal chemical vapor deposition (CVD) furnace, with Ni nano-particles as catalyst and ethylene as carbon source. XRD and SEM were used to examine the as-synthesized products. The result indicates that the pyrolysis temperature of 900°C is the most suitable to produce the carbon nanolines. The dimension and length of carbon nanolines are about 20nm and are well distributed, respectively. The as-synthesized carbon nanolines/carbon cloth is convenient and low-cost for adsorption materials of wastewater treatment, reinforcement of carbon/carbon composites. The growth mechanism of the as-synthesized carbon nanolines is simplely discussed.