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Effects of organic and inorganic metal salts on thermogravimetric pyrolysis of biomass components
Shilin Zhao,Meng Liu,Liang Zhao,Jianhong Lu 한국화학공학회 2017 Korean Journal of Chemical Engineering Vol.34 No.12
Thermogravimetric analyzer (TGA) was employed to elucidate the catalytic effects of organic and inorganic metal salts (K2CO3, KAc, Na2CO3 and NaAc) on the pyrolysis of three biomass components (cellulose, hemicellulose and lignin). In case of cellulose, TG analysis results showed that all the four metal salts increased the yield of char products and decreased the weight loss rates of cellulose pyrolysis, which followed the order of Na2CO3>K2CO3> NaAc>KAc. In contrast to cellulose, the four organic and inorganic salts employed had no significant effects on the remaining two biomass components:, hemicellulose and lignin. However, the four metal salts led to the devolatilization reaction of hemicellulose to occur at lower temperature region, and the dehydration reaction of lignin was promoted more or less. An increase in the heating rate might augment the maximum degradation rate. Different mixing ratios had little influence on the progress of catalytic pyrolysis. Based on the observations, the potential mechanism of the catalytic pyrolysis of biomass components with metal salts was discussed.
Xu Yuxuan,Tu Chuanjun,Liu Yanli,Liu Ping,Chen Gang,Tan Jiao,Xiong Wei,He Yubo,Liang Shilin,Ma Qingchun 한국탄소학회 2022 Carbon Letters Vol.32 No.5
High-temperature friction performances of graphite blocks (GBs) and zinc phosphate impregnated graphite blocks (IGBs) were evaluated under various friction temperatures. The surface of IGB exhibited extremely lower average friction coefficient values, that was 0.007 at 400 °C and 0.008 at 450 °C, in comparison to that of GB (0.13 at 400 °C and 0.16 at 450 °C, respectively). The worn surface of IGB in the high-temperature friction test was smoother and more complete than that of GB. The wear under high temperature and load caused the transformation of zinc pyrophosphate to zinc metaphosphate and the formation of a continuous large-area boundary lubrication layer combined with graphite and metallic element on the wear surface. The superior tribology property of IGB could be attributed to the digestion of iron oxides by tribo-chemical reactions and passivation of the exposed dangling covalent bonds. Specifically, the layered structure generated on the IGB wear interface effectively decreased the adhesive forces and prevented the surface from serious damage.