scholarly journals Effects of calcium on the evolution of nitrogen during pyrolysis of a typical low rank coal

2019 ◽  
Vol 7 (2) ◽  
pp. 397-404
Author(s):  
Xiongchao Lin ◽  
Sasha Yang ◽  
Xujun Chen ◽  
Panpan Zheng ◽  
Yonggang Wang ◽  
...  
Keyword(s):  
Free Radicals ◽  
Pyrolysis Temperature ◽  
Low Rank ◽  
Mineral Matter ◽  
Condensation Polymerization ◽  
Coal Pyrolysis ◽  
Decomposition Reactions ◽  
Gaseous Products ◽  
Secondary Reactions ◽  
Different Temperatures

AbstractThis study aims to investigate the effects of calcium on the migration of nitrogen in coal (coal-N) to N-containing gas species, particularly, NH3 and HCN (volatile-N) in volatiles, as well as the chemical transformation of the N in char during coal pyrolysis under different temperatures. The pyrolysis experiments of Shengli brown coal and its derived coal samples loaded with different contents of calcium were conducted under 600–800 °C in a novel fluidized bed reactor. The experimental results showed that during coal pyrolysis, the generation of NH3 is mainly derived from secondary reactions among volatiles, tar and char with the catalytic effect of mineral matter, especially calcium in coal. Increasing pyrolysis temperature from 600 to 800 °C could enhance the release of N in coal to volatiles. Meanwhile, the increased pyrolysis temperature could also inhibit the generation of NH3 while facilitating the formation of HCN. The release of HCN is more sensitive to pyrolysis temperatures. Specifically, under higher pyrolysis temperatures, more N-containing structures in coal would become thermally unstable and crack into HCN; On the other hand, higher pyrolysis temperature could also enhance the decomposition of N in coal to N-containing species in tar or N2, thus reducing the release of HCN and NH3. Nitrogen in tar could either undergo secondary decomposition reactions, generating NH3, HCN, N2 and other N-containing species in gas phase, or experience condensation polymerization by forming macromolecular structure and be retained in char at high pyrolysis temperatures. Calcium could significantly restrain the release of N from coal, thus reducing the yields of NH3 and HCN. During coal pyrolysis, calcium catalytically enhances the fracture and combination of chemical bonds, generating abundant free radicals. These free radicals could continuously attack N-containing structures and consequently release the N-containing gaseous products, such as NH3, HCN, N2 etc., resulting in the decrease of N in char. Calcium also plays important roles in nitrogen transformation in char during coal pyrolysis by catalytically intensifying the transformation of N in char from pyridinic nitrogen (N-6) and pyrrolic nitrogen (N-5) to quaternary type nitrogen (N-Q) during coal pyrolysis.

Effects of Zn on Pyrolysis Characteristics of Shenhua Lignite

2014 ◽  
Vol 1008-1009 ◽  
pp. 247-251
Author(s):  
Wipawan Sangsanga ◽  
Chuan Na ◽  
Jin Xiao Dou ◽  
Jiang Long Yu
Keyword(s):  
Pyrolysis Temperature ◽  
Fixed Bed ◽  
Coal Pyrolysis ◽  
Pyrolysis Gas ◽  
Gaseous Products ◽  
Pyrolysis Characteristics ◽  
Maximum Value ◽  
Product Gas ◽  
Zn Content ◽  
Catalytic Effects

The catalytic effects of Zn on the release of the gaseous products during pyrolysis of Shenhua lignite was investigated by using a fixed-bed quartz reactor. The product gas compositions from the coal pyrolysis were analyzed by a gas chromatography (GC). Experimental results show that Zn had noticeable catalytic effects on lignite pyrolysis. With the increase in Zn content, lignite weight loss increases during pyrolysis. However, there was an optimum content for amount Zn into the coal. Pyrolysis temperature had a great impact on the composition of pyrolysis gas. As the pyrolysis temperature increased, char yield decreased and gas yield increased. There existed a temperature that tar yield reached its maximum value.

scholarly journals Pyrolysis of Table Sugar

2013 ◽  
Vol 2013 ◽  
pp. 1-3
Author(s):  
Adnan Bulut ◽  
Selhan Karagöz
Keyword(s):  
Pyrolysis Temperature ◽  
Relative Concentration ◽  
Fixed Bed ◽  
Liquid Product ◽  
Fixed Bed Reactor ◽  
Gas Chromatography Mass Spectrometry ◽  
Gaseous Products ◽  
Hydroxymethyl Furfural ◽  
Liquid Products ◽  
Different Temperatures

Table sugars were pyrolyzed at different temperatures (300, 400, and 500°C) in a fixed-bed reactor. The effect of pyrolysis temperature on yields of liquid, solid, and gaseous products was investigated. As expected the yield of liquid products gradually increased and the yield of solid products gradually decreased when the pyrolysis temperature was raised. The yield of liquid products was greatest (52 wt%) at 500°C. The composition of bio-oils extracted with diethyl ether was identified by means of gas chromatography mass spectrometry (GC-MS), nuclear magnetic resonance (1H-NMR), and Fourier transform infrared spectroscopy (FTIR). The following compounds were observed in bio-oils produced from the pyrolysis of table sugar at 500°C: 1,4:3,6-dianhydro-α-d-glucopyranose, 5-(hydroxymethyl) furfural, 5-acetoxymethyl-2-furaldehyde, and cyclotetradecane liquid product. The relative concentration of 5-(hydroxymethyl) furfural was the highest in bio-oils obtained from pyrolysis of table sugars at 500°C.

Self-diffusion of lignite/water under different temperatures and pressure: A molecular dynamics study

2016 ◽  
Vol 30 (01) ◽  
pp. 1550253 ◽  
Author(s):  
Xinjian Liu ◽  
Yu Jin ◽  
Congliang Huang ◽  
Jingfeng He ◽  
Zhonghao Rao ◽  
...  
Keyword(s):  
Molecular Dynamics ◽  
Water System ◽  
Simulation Method ◽  
The Self ◽  
Dynamics Simulation ◽  
Low Rank ◽  
Self Diffusion ◽  
Change Mechanism ◽  
Different Temperatures ◽  
Temperature And Pressure

Temperature and pressure have direct and remarkable implications for drying and dewatering effect of low rank coals such as lignite. To understand the microenergy change mechanism of lignite, the molecular dynamics simulation method was performed to study the self-diffusion of lignite/water under different temperatures and pressure. The results showed that high temperature and high pressure can promote the diffusion of lignite/water system, which facilitates the drying and dewatering of lignite. The volume and density of lignite/water system will increase and decrease with temperature increasing, respectively. Though the pressure within simulation range can make lignite density increase, the increasing pressure showed a weak impact on variation of density.

The interaction between the char solid heat carrier and the volatiles during low-rank coal pyrolysis

2018 ◽  
Vol 136 ◽  
pp. 160-168 ◽  
Author(s):  
Xiao-hong Li ◽  
Bao-fu Li ◽  
Da-qing Fu ◽  
Jie Feng ◽  
Wen-ying Li
Keyword(s):  
Heat Carrier ◽  
Low Rank ◽  
Coal Pyrolysis ◽  
Low Rank Coal

scholarly journals Pyrolysis-GC/MS Analysis of Fast Growing Wood Macaranga Species

2021 ◽  
Vol 6 (1) ◽  
pp. 141-158
Author(s):  
R.R. Dirgarini J.N. Subagyono ◽  
Ying Qi ◽  
Alan L. Chaffee ◽  
Rudianto Amirta ◽  
Marc Marshall
Keyword(s):  
Thermal Degradation ◽  
Pyrolysis Temperature ◽  
Woody Biomass ◽  
Biofuel Production ◽  
Flash Pyrolysis ◽  
Fast Growing ◽  
Ms Analysis ◽  
Bio Oil ◽  
Different Temperatures ◽  
High Yields

Py-GC/MS analysis of six different species of fast growing Macaranga wood has been studied. Flash pyrolysis was conducted at different temperatures (250-850 oC) under a flow of helium followed by GC/MS analysis of the products. The total pyrolysis yields of the six different species of Macaranga were mostly between 40 and 90% within the range of pyrolysis temperature applied.  Pyrolysis of the woody biomass produced compounds which are mostly derived from thermal degradation or volatilization of lignin and cellulose/hemicellulose, the original major constituents of the biomass. The Py-GC/MS technique indicated that M. gigantea was the most potential species for biofuel production and the optimum pyrolysis temperature to produce high yields of bio-oil was 450 oC.

Temperature sensitivity of simulated soils with biochars produced at different temperatures

Soil Research ◽  
2019 ◽  
Vol 57 (3) ◽  
pp. 294 ◽  
Author(s):  
Xiaojie Wang ◽  
Guanhong Chen ◽  
Renduo Zhang
Keyword(s):  
Organic Matter ◽  
Dissolved Organic Matter ◽  
Temperature Sensitivity ◽  
Pyrolysis Temperature ◽  
Soil C ◽  
Ambient Temperatures ◽  
C Pools ◽  
C Cycle ◽  
Microbial Enzyme ◽  
Different Temperatures

The temperature sensitivity of multiple carbon (C) pools in the soil plays an important role in the C cycle and potential feedback to climate change. The aim of this study was to investigate the temperature sensitivity of different biochars in soil to better understand the temperature sensitivity of different soil C pools. Biochars were prepared using sugarcane residue at temperatures of 300, 500 and 800°C (representing different C pools) and C skeletons (representing the refractory C pool in biochar) were obtained from each biochar. The sugarcane residue, biochars and C skeletons were used as amendments in a simulated soil with microbes but without organic matter. The temperature sensitivity of the amended soils was characterised by their mineralisation rate changes in response to ambient temperatures. The temperature sensitivity of treatments with relatively refractory biochars was higher than that with labile biochars. The temperature sensitivity of treatments with biochars was lower than for their corresponding C skeletons. The different temperature sensitivity of treatments was attributable to the different internal C structures (i.e. the functional groups of C=C and aromatic structure) of amendments, determining the biodegradability of substrates. Dissolved organic matter and microbial enzyme activity of biochars were lower than those of corresponding C skeletons, and decreased with increasing pyrolysis temperature. The temperature sensitivities of treatments with biochars, C skeletons and sugarcane residue were negatively correlated with the properties of dissolved organic matter and microbial enzyme activities (especially dehydrogenase) in soil.

The chemical nature of supercritical gas extracts from low-rank U. K. coals

1981 ◽  
Vol 300 (1453) ◽  
pp. 183-192 ◽  
Keyword(s):  
Spectroscopic Analysis ◽  
Chemical Nature ◽  
Development Programme ◽  
Low Rank ◽  
Mineral Matter ◽  
Gas Extraction ◽  
Chemical Structures ◽  
Aromatic Clusters ◽  
Methylene Ether ◽  
Average Structures

Two processes are being developed by the National Coal Board for producing liquids from coal. Both involve extraction of the coal to produce an extract, freed from mineral matter, which is then catalytically hydrocracked. This approach is particularly suitable for producing transport fuels and chemical feedstocks. One process uses as solvent a process-derived liquid. The other uses a compressed supercritical gas to extract the more hydrogen-rich parts of the coal, leaving a reactive char which can provide the necessary hydrogen, heat and power for the process. As part of the development programme, extracts have been prepared by gas extraction over a range of conditions, and their chemical structures investigated by elemental and spectroscopic analysis. The average structures so derived consist of small aromatic clusters joined by methylene, ether and diphenyl linkages. Extracts produced by the liquid solvent route contain larger aromatic clusters.

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