Mingqiang Chen

The kinetics model and pyrolysis behavior of the aqueous fraction of bio-oil

The pyrolysis behavior and kinetics of the aqueous fraction of bio-oil were studied through thermogravimetric (TG) analysis. Based on the experimental data, activation energies and kinetic parameters were calculated by the Achar differential method and the Coats-Redfern integral method, then the most probable mechanism functions and kinetics model were obtained at last. The results show that the pyrolysis of bio-oil aqueous fraction can be divided into three stages, that is, the volatilization of volatile fractions, the decomposition stage of heavy fractions and char combustion. The experimental results show that the activation energy of volatilization is higher than that of the decomposition stage. The first stage was expressed as the first order reaction and the second stage the second order reaction. The correlation coefficient between the two stages illustrates that the reactions are in well conformity with each other and the calculated value of conversion is consistent with the experimental results.

Hydrogen production by steam reforming for glycerol as a model oxygenate from bio-oil

Glycerol is a model whose ingredients are dominant in bio-oil, that is the reason why this thesis chooses glycerol as the model to pyrolyze biomass into oil. The thesis adopts coprecipitation method to produce a series of Ni-based catalysts, researches the rules and principles of restructuring glycerol into hydrogen in gasification reactor and explores the reaction conditions and reaction principles to restructure glycerol and to produce hydrogen. The result of this experiment shows that Ni-dolomite catalyst, in addition with oxide MgO or oxide CoO, greatly improves the activities of catalyst and effectively reduces the rate of carbon deposition. In order to study the restructuring reaction-temperature, ratio of water-carbon as well as the effect of feeding flow rate on the restructuring glycerol into hydrogen by steam catalysis, the thesis chooses Ni/MgO-CoO-dolomite as catalyst and the productivity of H2, CO, CH4, CO2 in reaction gas as research index. The ideal reaction condition is acquired as follow: reaction temperature is 650–700°C; S/C is 8–10 and feeding flow rate is 2.5–4ml/min.

Catalytic effects of several additives on co-pyrolysis of tobacco stalk and waste rubber tire powder

The components and yield of the oil obtained by co-pyrolysis of a mixture of tobacco stem and waste rubber tire powder were investigated. The results shows that 450°C is an optimal temperature in terms of liquid product yield when the reactants are mixtures of tobacco stem and waste rubber tire powder with a mass ratio of 1∶1. It is found that the liquid product from co-pyrolysis contains less water and oxygen element, and meanwhile, hydrocarbon content increases to some degree compared with that from pyrolysis of solo pyrolysis of tobacco stem, which means the oil from co-pyrolysis is improved. However, how to improve the liquid product quality further and how to control the hazardous element emissions via co-pyrolysis needs still further studies.

Hydrogen production from steam reforming of ethylene glycol over iron loaded on MgO

In this study, a series of Fe-based catalysts loaded on MgO were prepared by a precipitation technique. And they were tested in hydrogen production from steam reforming of ethylene glycol (SRE), which was a representative model compound of fast bio-oil. The catalysts were characterized by XRD, SEM and H2-TPR analysis. The results showed that the crystalline phases of catalysts contained Fe2O3 (Hematite), Fe3O4 (Magnetite), Fe2MgO4 (iron magnesium oxide) and MgO, and morphology of MgO was changed from the rugby-ball like particles to spherical particles with the addition of Fe. In addition, the catalytic test results indicated that the 18%Fe/MgO catalyst exhibited the highest ethylene glycol conversion (∼99.8%) and H2 molar percent (∼77%) during at the following conditions: H2O/C molar ratio is 5∼7, the feeding rate is 14 mL/h and the reaction temperature at 600∼650°C. Furthermore, the 18%Fe/MgO catalyst can keep outstanding stability during SRE for 12 h.

Gasification of Acetic Acid as a Model Oxygenate from Bio-Oil by Microwave Heating

Acetic acid was chosen as a model compound of fast pyrolysis bio-oil, A series of Ni-based catalyst were prepared for gasification of acetic acid in a fixed bed by microwave heating. The experimental results indicate that the additives of MgO and CoO to the Ni/Dolomite can improve the catalyst selectivity obviously, at the same time, Ni/Dolomite catalyst can reduce the carbon deposition rate efficiently. Here we have conducted the gasification of acetic acid with Ni/MgO- CoO-Dolomite and H2,CH4,CO,CO2 as indicator in a fixed bed by microwave heating for the purpose of obtaining some knowledge of its behavior under different conditions. The effects of the reactor temperature, feeding rate, molar ratio of H2O/C on yields of gas and composition of gaseous product have been investigated and the liquid product has been qualitatively analyzed. the optimum conditions is microwave temperature 750℃-900℃,H2O to carbon ratio 4-7 and feeding rate 2.5-3.2ml/min.

Combustion characteristics and kinetic analysis of bio-oil from fast pyrolysis of biomass

The combustion characteristic of bio-oil from fast pyrolysis of pine wood sawdust in oxygen atmosphere at various heating rates was investigated by thermogravimetric analysis. It is found that there are three stages for combustion process of bio-oil:vaporization of water and devolatilization process of volatilizable components, pyrolysis process of non-volatilizable oligomers and lignin pyrolysis products, rapid combustion process of secondary coke formed by the previous two stages. According to TG data, the most probable mechanism functions selected from 22 kinetic functions in the temperature range of 400-430°C were determined and the kinetic parameters were calculated by Popescu method. It can be concluded that the combustion process in the above temperature range is a chemical reaction control process. Kinetic equations are da/dt=Ae^-E/RT(1-α)² (400-406°C), da/dt =0.5Ae^-E/RT(1-α)³ (406-416°C) and da/dt=2Ae^-E/RT(1-α)^3/2 (416-430°C) respectively.