This paper reports a new approach to estimate kinetic parameters for the thermal decomposition of the solid state from TG-DTG or DSC curve.Reduced equations are derived for the first tlme.The validity of these equatio...This paper reports a new approach to estimate kinetic parameters for the thermal decomposition of the solid state from TG-DTG or DSC curve.Reduced equations are derived for the first tlme.The validity of these equations was demonstrated employing data obtained from the dehydration process of calcium oxalate monohydrate.展开更多
The physical and chemical properties of the air-dried residual coal after soaking in the goaf will change,resulting in an increase in its spontaneous combustion tendency.This study aimed to look into the features and ...The physical and chemical properties of the air-dried residual coal after soaking in the goaf will change,resulting in an increase in its spontaneous combustion tendency.This study aimed to look into the features and mechanism of soaked-dried coal's spontaneous combustion.Five samples of coal were dried to various degrees,and the weight loss features during thermal processing were examined.Based on this,the pore structure and chemical structure characteristics of the coal samples with the highest tendency to spontaneous combustion were quantitatively examined,and the mechanism by which soaking-drying afected the spontaneous combustion heating process of the remaining coal in goaf was investigated in turn.The results show that T1 decreases with the increase of drying time,T2–T6 shows a fuctuating change,and the ignition activation energy of 36-S-Coal is smaller than that of other coal samples.The pore type of 36-S-Coal changes from a oneend closed impermeable pore to an open pore,and the pore group area is large.During the 36 h drying process,the internal channels of the coal were dredged,and a large number of gravels and minerals were precipitated from the pores with the air fow.A large number of gravels were around the pores to form a surface structure that was easy to adsorb various gases.Furthermore,infrared spectroscopy was used to analyze the two coal samples.It was found that soaking and drying did not change the functional group types of coal samples,but the fatty chain degree of 36-S-Coal was reduced to 1.56.It shows that the aliphatic chain structure of coal is changed after 36 h of drying after 30 days of soaking,which leads to the continuous shedding of aliphatic chain branches of residual coal,and the skeleton of coal is looser,which makes the low-temperature oxidation reaction of 36-S-Coal easier.Based on the above results,the coal-oxygen composite mechanism of water-immerseddried coal is obtained,and it is considered that the key to the spontaneous combustion oxidation process of coal is to provide oxygen atoms and accelerate the formation of peroxides.展开更多
The kaolinite-polyacrylamide inte rcalation compound was prepared fir st by the displacement reaction of th e kaolinite-formamide intercalatio n precursor with 30%acrylamide ethanol solution,and then the polymeriz ati...The kaolinite-polyacrylamide inte rcalation compound was prepared fir st by the displacement reaction of th e kaolinite-formamide intercalatio n precursor with 30%acrylamide ethanol solution,and then the polymeriz ation under 140℃for 15h with the catalysis of dibenzoyl peroxide.The XRD analy ses showed that the basal spacings of kaolinite-acrylamide intercalation compound and kaolinite-polyacry lamide compound were 1.135nm and 1.144nm respectively.The kaolinite-polya crylamide compound was able to resis t to 30-min washing with water,but th e kaolinite-acrylamide compound was unstable during washing.FT-IR proved that the hydrogen bonds were forme d between kaolinite Si-O group and polyacrylamide NH group and between kaolinite inner surface hydroxyl and polyacrylamide C =O group,and that p arts of NH group keyed into the kaolin ite ditrigonal hole.TG and DTG analysis proved that kaolinite-polyacrylamide was stable under 350℃.A net weight loss of 16.63%between 370℃～500℃is due to the removal of interca lated polyacrylamide from the interlamellar space of kaolinite.These results clearly indicate that acrylamide has been intercalated into the layers of kaolinite and was polymerized in-situ.Based on the TG data,the formula of the kaolinite-polyacrylami de intercalation compound,Al 2 Si 2 O 5 (OH) 4 CH 2 CHCONH 2 0.736 ,can be calculated.展开更多
文摘This paper reports a new approach to estimate kinetic parameters for the thermal decomposition of the solid state from TG-DTG or DSC curve.Reduced equations are derived for the first tlme.The validity of these equations was demonstrated employing data obtained from the dehydration process of calcium oxalate monohydrate.
基金supported by the fnancial support of the General Projects of National Natural Science Foundation of China(52074156).
文摘The physical and chemical properties of the air-dried residual coal after soaking in the goaf will change,resulting in an increase in its spontaneous combustion tendency.This study aimed to look into the features and mechanism of soaked-dried coal's spontaneous combustion.Five samples of coal were dried to various degrees,and the weight loss features during thermal processing were examined.Based on this,the pore structure and chemical structure characteristics of the coal samples with the highest tendency to spontaneous combustion were quantitatively examined,and the mechanism by which soaking-drying afected the spontaneous combustion heating process of the remaining coal in goaf was investigated in turn.The results show that T1 decreases with the increase of drying time,T2–T6 shows a fuctuating change,and the ignition activation energy of 36-S-Coal is smaller than that of other coal samples.The pore type of 36-S-Coal changes from a oneend closed impermeable pore to an open pore,and the pore group area is large.During the 36 h drying process,the internal channels of the coal were dredged,and a large number of gravels and minerals were precipitated from the pores with the air fow.A large number of gravels were around the pores to form a surface structure that was easy to adsorb various gases.Furthermore,infrared spectroscopy was used to analyze the two coal samples.It was found that soaking and drying did not change the functional group types of coal samples,but the fatty chain degree of 36-S-Coal was reduced to 1.56.It shows that the aliphatic chain structure of coal is changed after 36 h of drying after 30 days of soaking,which leads to the continuous shedding of aliphatic chain branches of residual coal,and the skeleton of coal is looser,which makes the low-temperature oxidation reaction of 36-S-Coal easier.Based on the above results,the coal-oxygen composite mechanism of water-immerseddried coal is obtained,and it is considered that the key to the spontaneous combustion oxidation process of coal is to provide oxygen atoms and accelerate the formation of peroxides.
文摘The kaolinite-polyacrylamide inte rcalation compound was prepared fir st by the displacement reaction of th e kaolinite-formamide intercalatio n precursor with 30%acrylamide ethanol solution,and then the polymeriz ation under 140℃for 15h with the catalysis of dibenzoyl peroxide.The XRD analy ses showed that the basal spacings of kaolinite-acrylamide intercalation compound and kaolinite-polyacry lamide compound were 1.135nm and 1.144nm respectively.The kaolinite-polya crylamide compound was able to resis t to 30-min washing with water,but th e kaolinite-acrylamide compound was unstable during washing.FT-IR proved that the hydrogen bonds were forme d between kaolinite Si-O group and polyacrylamide NH group and between kaolinite inner surface hydroxyl and polyacrylamide C =O group,and that p arts of NH group keyed into the kaolin ite ditrigonal hole.TG and DTG analysis proved that kaolinite-polyacrylamide was stable under 350℃.A net weight loss of 16.63%between 370℃～500℃is due to the removal of interca lated polyacrylamide from the interlamellar space of kaolinite.These results clearly indicate that acrylamide has been intercalated into the layers of kaolinite and was polymerized in-situ.Based on the TG data,the formula of the kaolinite-polyacrylami de intercalation compound,Al 2 Si 2 O 5 (OH) 4 CH 2 CHCONH 2 0.736 ,can be calculated.
